LTE-A PUCCH多用户接收算法研究

LTE-A系统使用参考信号进行上行信道估计,而使用PUCCH format 2a/2b发送上行控制信息时,由于每个时隙只有一个SC-FDMA符号可以用于传输参考信号,所以此时接收端不能直接利用参考信号进行信道估计.给出了一种易实现且复杂度低的PUCCH 2a./2b的半盲检测接收算法,该算法利用ACK/NACK信息辅助信道估计.仿真结果表明,文中提出的方法能有效提高PUCCH 2a/2b的接收性能.     

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通过建立检漏结果不确定度的评定模型,应用蒙特卡罗方法对检漏数据进行随机模拟,获得了各输入量的随机样本,计算了检漏结果的不确定度,并与传统评定方法得到的不确定度进行了比较和分析。研究表明,两种方法计算得到的不确定度一致,说明蒙特卡罗方法可以作为评定氦质谱检漏结果不确定度的有效方法,且蒙特卡罗评定方法计算效率更高,应用范围更广。     

Reference measurement procedure for Δ9-tetrahydrocannabinol in serum

An isotope dilution gas chromatography/mass spectrometry (ID-GC/MS) reference measurement procedure for Δ9-tetrahydrocannabinol (THC) in serum was developed and validated. The method complies with the concept of a ratio primary reference measurement procedure. The uncertainty was determined for two concentrations of THC in serum (1 ng/mL and 2.4 ng/mL). The calculation procedure is based on the Guide to the Expression of Uncertainty in Measurement (GUM). The relative expanded uncertainty was found to be less than 2% for both concentration levels, corresponding to a 95% confidence interval. For the reference method, it was shown that the measurement of THC within the concentration range covered by the current threshold values is very accurate. The method has the potential to provide traceability for the methods used in practical forensics.     

A new nondestructive technique for measuring pressure in vessels by surface waves

Thin-walled pressure vessels are widely used in modern industry. It is important to measure pressure of the vessels. It has been proved that the velocity of ultrasonic propagation in the material could be affected by the stresses applied to it. The pressure measurement should consider the effect of temperature as the velocity of ultrasonic is affected by the temperature and thermo-stress is produced in the vessels wall. Furthermore, the propagation distance of ultrasonic is influenced by thermal deformation due to temperature changes. In consideration of these influencing factors, a modified model of pressure measurement has been developed, and according to this model, a reference method for the temperature compensation is presented. The relationship between the time delay and pressure was established through this method. The correlative time estimation method based on Hilbert-Huang Transform is presented to estimate the time delay. Therefore, a new method for measuring the pressure of thin-walled vessels nondestructively is presented. Two vessels made of different kinds of materials were used as specimens in our experiments. The results obtain from the tests are used to validate the modified model and demonstrate that the reference method is effective.     

适用于钢筋混凝土腐蚀监测的长效MnO2参比电极的研制

以电解法制备的MnO₂粉体为原料,研制了可用于混凝土环境中的固体MnO₂长效参比电极. 在饱和Ca(OH)₂溶液中近一年的监测数据显示,该参比电极具有较好的电位稳定性和抗干扰能力,其电极电位的漂移< 10 mV. EIS和极化曲线测试结果表明,相对于化学法合成的MnO₂电极,电解法制备的MnO₂参比电极具有较小的内阻、较大的交换电流密度、较强的抗极化能力和较低的温度系数（~ 0.68 mV·°C^-1）. 在硬化砂浆中的长期测试表明,该电极在混凝土中的电极电位基本不受Cl^-、有机胺阻锈剂的影响,能作为埋入式参比电极,满足混凝土中Cl^-浓度、pH值和钢筋半电池电位的长期监测的要求,这对于海洋混凝土工程的耐久性监测具有较高的应用价值.     

计算机模拟取样确定标准物质的最小取样量

本文提出用计算机模拟取样对不同的取样量重复进行测试多次,统计其检测结果的标准偏差,做出标准偏差s对取样量m的拟合曲线,再计算最小取样量。设计的模式是一颗一颗地取样,这样不存在取样操作及测试过程带来的误差,操作是可行的,结果是可靠的。计算机运算速度快,参数转换方便,也可以取毫克甚至亚毫克样进行实验。只要有足够的岩矿鉴定的资料,可以模拟不同状态下的样品取样过程。     

Establishment of SI-traceable reference values for the content of various elements in the IMEP-14 sediment sample

For the first time in the International Measurement Evaluation Programme (IMEP)-14, a sediment sample was offered to analytical laboratories to perform measurements of As, Cd, Cr, Cu, Fe, Pb, Hg, Ni, U and Zn. In line with IMEP policy, the results were presented according to the certified / assigned reference values established by several reference laboratories around the world. The certification campaign is described in detail. Isotope dilution mass spectrometry was applied as a primary method of measurement, whenever possible, to achieve SI-traceable results. For reference measurements of As, Fe, Hg and Zn, k₀-neutron activation analysis and Zeeman atomic absorption spectrometry were applied. The reference values (ranges) were characterised as ”certified” (for Cd, Cr, Pb, Ni and U) or ”assigned” (for As, Cu, Fe, Hg and Zn) according to IMEP policy. The measurement uncertainty of the certified / assured reference values was calculated according to the ISO/BIPM Guide. Received: 7 June 2001-10-27 Accepted: 19 August 2001     

高分辨率合成孔径激光雷达关键技术分析

本文从提高分辨率的角度,详细介绍了合成孔径激光雷达系统采用的线性调频技术、解线频调技术、参考通道技术、相干探测技术、平衡接收技术等关键技术。通过分析了这些技术的主要特点和实施条件,指出了需要进一步深入研究的问题,以期为合成孔径激光雷达系统的设计和研发提供参考。     

基于LDO稳压器的带隙基准电压源的设计

基准模块是LDO线性稳压器的核心部分,它是影响稳压器精度的关键因素之一。本文针对LDO线性稳压器对基准模块一方面有较高的精度要求,另一方面又有较低静态电流要求的矛盾设计了一款简单实用的电压基准电路。仿真结果表明该电路在-40~140℃的温度系数为7.7′10-6℃,低频时的电源抑制比可达-76dB,基准源电路的供电电压范围为2~4.5V。