计量检定室内温度和相对湿度的测定

1　室内温度的测定一般精度的空调系统 ,可用 0 1℃分度的水银温度计测定 ,高精度的空调系统可用 0 0 1℃的水银温度计或小量程温度自动记录仪测定。2　室内相对湿度的测定可用带小风扇的干湿球温度计或电湿度计测定。使用干湿球温度计时应注意 :(1)包裹湿球温度计的纱布力求松软 ,并有良好的吸水性 ;(2 )测定时 ,应尽快读数 ,并避免对着温、湿度计急速呼吸 ,以保证测定的准确性 ;(3)纱布未浸水前 ,干球温度计和湿球温度计的读数差不应大于 0 1℃。使用电湿度计时应注意 :(1)测头是关键部件 ,易损坏 ,需特别小心。使用时 ,只能拿测头的塑…     

选择计量器具检定周期的几点建议

合理选择计量器具检定周期,可以从以下几个方面考虑:     

无梭织机经纱张力波动特点与微机控制电子送经系统分析

分析了无梭织机经纱张力波动特点以及电子送经系统检测和补偿经纱张力的原理。通过对四种电子送经后梁系统的分析指出：①高频率的经纱张力波动由弹性后梁的高速摆动来补偿；低频率的经纱张力波动由电子送经装置通过送经量的调节来补偿。②以拉力传感器作为检测元件时，送经装置是以一个织造周期中经纱张力的平均值作为控制目标进行张力的ＰＩＤ控制；以接近开关作为检测元件时送经装置则是通过检测后梁的位置进行张力控制。③对ＪＡＴ６００喷气织机以拉力传感器作为检测元件的ＰＩＤ控制模式进行了详尽的分析说明。     

通辽市科尔沁区灌溉用水效率评价

准确评价区域灌溉用水效率的发展水平,对提高当地灌溉管理水平和完善水利工程设施有很大的作用。以通辽市科尔沁区为例,根据1995~2010年的灌溉用水情况,分别采用单因素评价和层次分析法（AHP）进行综合评价灌溉用水效率。结果表明,两种评价方法结果相似,科尔沁区的灌溉用水效率已显著提升,水平较高。     

生态猪的健康养殖与疾病预防技术

根据影响生态猪健康成长的几点要素,合理阐述如何实施更好的生态猪养殖。对当前现有的生态猪养殖模式进行科学分析,总结养殖要点。结合实际情况,提出生态猪疾病预防的有效措施,对生态猪养殖未来发展趋势做出讨论。     

适用于中国UWB标准0.18μm CMOS发射机前端研制

基于0.18 μm CMOS工艺设计了一款适用于中国超宽带(UWB)标准的发射机前端.该发射机前端通过在片内集成有源巴仑,实现了信号先差分至单端转化、后信号放大的策略,不仅提高了系统集成度而且有利于降低系统功耗.同时,提出折叠PMOS跨导技术使混频器的线性度得以提升,利于增大发射链路中低频放大器的增益比重以减轻高频放大器的压力.最终,对前端电路应用并联峰化技术,满足了系统对带宽的要求.芯片采用COB(chip on board)方式测试,结果表明:射频输出端口在5～11.5 GHz内匹配良好,系统的IP-1dB约为-2 dBm.芯片面积为0.8 mm×1.1 mm,工作电压1.8 V时消耗电流20.4 mA.为中国超宽带(UWB)标准的进一步研究提供了参考.     

低渗透油藏渗吸采油技术研究进展*

针对低渗透油藏渗吸采油技术,运用文献调研的方式,介绍了渗吸采油相关概念,综述了低渗透油藏渗吸 采油技术在渗吸机理和应用方面的研究成果与最新研究进展,对低渗透油藏渗吸采油技术在室内实验和现场应 用中的发展趋势进行了技术展望。     

一种针对中国超宽带标准的CMOS PA

A 6–9 GHz ultra-wideband CMOS power amplifier (PA) for the high frequency band of China's UWB standard is proposed. Compared with the conventional band-pass filter wideband input matching methodology, the number of inductors is saved by the resistive feedback complementary amplifying topology presented. The output impendence matching network utilized is very simple but efficient at the cost of only one inductor. The measured S₂₂ far exceeds that of similar work. The PA is designed and fabricated with TSMC 0.18 μ m 1P6M RF CMOS technology. The implemented PA achieves a power gain of 10 dB with a ripple of 0.6 dB, and S₁₁ < –10 dB over 6–9 GHz, S₂₂ < –35 dB over 4–10 GHz. The measured output power at the 1 dB compression point is over 3.5 dBm from 6 to 9 GHz. The PA dissipates a total power of 21 mW from a 1.8 V power supply. The chip size is 1.1 × 0.8 mm².     

A 6-9 GHz ultra-wideband CMOS PA for China's ultra-wideband standard

A 6-9 GHz ultra-wideband CMOS power amplifier(PA) for the high frequency band of China's UWB standard is proposed.Compared with the conventional band-pass filter wideband input matching methodology,the number of inductors is saved by the resistive feedback complementary amplifying topology presented.The output impendence matching network utilized is very simple but efficient at the cost of only one inductor.The measured S_(22) far exceeds that of similar work.The PA is designed and fabricated with TSMC 0...     

A 264 MHz CMOS Gm-C LPF for ultra-wideband standard

A 264 MHz CMOS 4th G_m-C LPF target for the UWB standard is presented.The filter is designed by cascading two biquad cells.Compared with the previously published biquad cells,the biquad proposed here saves 1 transconductor,3 CMFB networks and 2 capacitors.Benefiting from these merits,the power consumption and chip area of the 4th order UWB LPF are reduced dramatically without other characteristics being affected.The LPF is designed and fabricated with TSMC 0.18μm 1P6M CMOS technology.The implemented LPF ...