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A method to determine precisely three-dimensional wire positions in the BESⅢ drift chamber using physics events is introduced. In part the proposed technique takes advantage of the possibility that the magnetic field can be turned off, thereby providing a huge sample of straight tracks for which effects due to multiple scattering, energy loss and non-uniformity of the magnetic field are minimized during the calibration process. A toy Monte Carlo study is performed to demonstrate the viability of the method. As a result of the calibration process, the rms of the distribution of wire position deviation is reduced from 35μm to 10μm. 相似文献
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The temperature dependence of Mn ion magnetization and the conductivity difference versus temperature provide phase separation evidence in Nd1-xSrxMnO3 (x=0.50, 0.51, 0.52, 0.53, 0.54, 0.55). This is different from other reports and may suggest that a fully charge-ordered state exists in quite a narrow range; the sample preparation procedure affects the charge ordering. The polaron effect also plays an important role in explaining the conductivity. 相似文献
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本文实现了一种数字控制PWM/PSM双模DC/DC Buck变换器。该变换器的两种工作模式可根据连续导通模式(CCM)或者断续导通模式(DCM)自动选择。变换器在DCM模式下工作于脉冲跨周期调制(PSM)模式,在CCM模式下工作于2MHz开关频率的脉冲调宽调制(PWM)模式。轻负载下通过跳周期工作降低了开关损耗。因此在宽负载范围内得到了较高的变换效率。文中详细阐述了PWM控制电路模块,例如模拟数字转换器(ADC),数字PWM(DPWM)和环路补偿器,以及PSM控制模块的实现。环路补偿器的参数可编程调节,以满足不同的外围器件参数以及开关频率。这一特性比模拟方式具有更大的灵活性。本文中实现的变换器采用0.13μm CMOS工艺设计并流片,芯片面积为1.21 mm2。测试结果显示变换效率在200mA负载时为90%,在20mA负载时为67%。同时,负载阶跃响应的测试结果说明了本文实现的双模变换器的良好稳定性。 相似文献
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A new tetranuclear cyanide-bridged complex [PPh4]2[NiⅡ(CN)4CuⅠ(PPh3)2]2·2CH3OH ([PPh4]+ = tetraphenylphosphine cation, PPh3 = triphenylphosphine) 1 has been synthesized and characterized by IR spectroscopy, elemental analysis, electronic absorption spectra and single-crystal X-ray diffraction. This complex crystallizes in triclinic, space group Pí with a = 10.910(5), b = 15.777(7), c = 18.275(8), α = 68.752(12), β = 79.776(13), γ = 81.400(14)°, NiCuC65H50N4OP3, Mr = 1122.25, V = 2873(2)3 , Z = 2, Dc = 1.293 g/cm3, F(000) = 1156, μ = 0.826 mm-1, the final R = 0.0755 and wR = 0.2155 for 7324 observed reflections (I > 2σ(I)). The title compound exhibits a discrete square tetranuclear structure and a cubic order NLO property. 相似文献
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随着教育技术的发展,传统课堂正在逐步被混合式学习方式所取代。多维度考核作为学生学习的指挥棒,保障混合式教学各环节得以实施。本文探索“线上单元测试+课前测+线下作业自评互评+线下课堂报告(或分组讨论)+线下期末考试(开卷闭卷相结合)”等多维度考核,注重学习过程考核,使考核评价更趋于合理。多维度考核本身也成为混合式教学实施的重要环节。 相似文献
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随着数字电视人机交互功能的不断增强,传统的EPG系统呈现出动态变化的趋势,基于双向网络对其进行优化设计,以满足更多用户的个性化需求。从软硬件设计和相关技术应用入手,探讨了数字电视中智能EPG系统的设计,并对设计结果进行了测试,测试结果表明,该智能EPG系统可以实现预期功能。 相似文献