放大电路高频响应分析再探

在分析放大电路的上限截止频率时,通常用密勒定理对共射电路进行单向化等效,可简化计算过程。但是分析表明,密勒定理不能解释共基和共集电路的上限截止频率比共射电路高的原因。在网络的上限截止频率附近,用主极点函数来表示网络的传递函数,就可以用网络的开路时间常数和表示网络上限截止频率的时间常数。运用主极点方法分析放大电路的上限截止频率,一眼即可看出,共基和共集电路的开路电阻远小于共射电路的开路电阻,因此它们的开路时间常数和比共射电路的小,它们的高频响应效果自然优于共射放大电路。由此可见,用放大电路的开路时间常数和分析上限截止频率,物理概念清晰,它适用于各种放大电路的高频响应分析。     

180t顶吹转炉溅渣护炉工艺冷态模拟试验

采用冷态模拟试验,通过测定溅到转炉炉衬上的渣量多少,确定最佳操作工艺参数·结果是在１１％渣量及２３０ｍ３·ｈ－１,２６８ｍ３·ｈ－１顶吹标准状态气体流量条件下,炉衬表面和炉帽部位的最佳溅渣枪位分别是１５５ｍｍ,１６５ｍｍ左右和１２５ｍｍ,１４５ｍｍ左右·     

Impact of climate change on wetland ecosystems: A critical review of experimental wetlands

Climate change is identified as a major threat to wetlands. Altered hydrology and rising temperature can change the biogeochemistry and function of a wetland to the degree that some important services might be turned into disservices. This means that they will, for example, no longer provide a water purification service and adversely they may start to decompose and release nutrients to the surface water. Moreover, a higher rate of decomposition than primary production (photosynthesis) may lead to a shift of their function from being a sink of carbon to a source. This review paper assesses the potential response of natural wetlands (peatlands) and constructed wetlands to climate change in terms of gas emission and nutrients release. In addition, the impact of key climatic factors such as temperature and water availability on wetlands has been reviewed. The authors identified the methodological gaps and weaknesses in the literature and then introduced a new framework for conducting a comprehensive mesocosm experiment to address the existing gaps in literature to support future climate change research on wetland ecosystems. In the future, higher temperatures resulting in drought might shift the role of both constructed wetland and peatland from a sink to a source of carbon. However, higher temperatures accompanied by more precipitation can promote photosynthesis to a degree that might exceed the respiration and maintain the carbon sink role of the wetland. There might be a critical water level at which the wetland can preserve most of its services. In order to find that level, a study of the key factors of climate change and their interactions using an appropriate experimental method is necessary. Some contradictory results of past experiments can be associated with different methodologies, designs, time periods, climates, and natural variability. Hence a long-term simulation of climate change for wetlands according to the proposed framework is recommended. This framework provides relatively more accurate and realistic simulations, valid comparative results, comprehensive understanding and supports coordination between researchers. This can help to find a sustainable management strategy for wetlands to be resilient to climate change.     

最优的单纯形-中心设计

对于一般的ｑ－１维正规单纯形利益区域和多重线性多项式模型,给出了Ａ 最优的混料设计,Ａ 最优的混料设计的柱点是所有的正规单纯形的各类中心·令ｒｉ(ｉ＝１,２,…,ｑ)表示每个第ｉ类中心点上的设计测度,给出了以ｒｊ／ｒｑ(ｊ＝１,２,…,ｑ－１)形式表示的Ａ 最优测度比,按此测度比给出的广义单纯形中心设计是Ａ 最优的     

离子型稀土原地浸析采矿室内模拟试验研究

叙述了离子型稀土矿用原地浸析采矿开采时进行室内模拟浸析试验的原矿样采集与加工、试验装置、试验内容．论述和分析了试验情况．得出了对该类矿山的原地浸析开采设计有重要参考价值的试验参数     

中国核电厂操纵员不响应概率的实验研究

详细描述了有关中国核电厂操纵员可靠性（ＣＯＲＥ）实验的目标、要求及实验安排．中国核电厂操纵员可靠性实验是在清华大学全尺寸核电厂模拟机上,按照ＩＡＥＡ所推荐的人误分类方法和ＰＳＡ中ＨＲＡ的研究重点,ＨＣＲ模型中人误机理以及操纵员与时间相关的不响应概率的统计分析理论进行的．研究小组开发了有关进行数据处理的计算机软件（ＨＲＡＳ）,分别叙述了有关实验准备工作及５４位中国操纵员在模拟机上所获得的数据和参数、操纵员不响应概率曲线的拟合、人的失误ＳＲＫ与ＣＰ模型的参数,与其他国家的结果的比较．此外,按照中国核电厂操纵员的特点,对有关威布尔参数及ＰＳＦ因子修正．最后,讨论了有关利用ＣＯＲＥ结果对ＰＳＡ中的ＨＲＡ的应用的结论和建议．     

数字化DPSK调制解调器的研究

现代通信系统要求通信距离远、通信容量大、传输质量好。作为其关键技术之一的调制解调技术一直是人们研究的一个重要方向。讨论和仿真实现了基于FPGA的数字化DPSK制解调系统。用Altera公司的FPGA开发平QuartusⅡ3．0实现了一个对基带信号的DPSK调制解调系统模型的仿真。     

分析化学实验教学改革探讨

从我校分析化学实验教学的实际情况出发,通过改革传统的实验内容,在基本操作训练的基础上增开一些设计性、综合性实验,更新教学手段,改革考核方式,提高学生的创新意识与动手能力。     

海拉尔盆地凝灰质砂岩溶蚀的实验方法研究

海拉尔盆地深层碎屑岩储层中高含凝灰质成分,显微镜分析表明储集空间类型以碳酸盐胶结物和长石类矿物溶蚀作用形成的次生孔隙为主。本文对凝灰质砂岩制成的铸体薄片进行了溶蚀实验,通过偏光显微镜观察对比溶蚀前后的矿物组合和孔隙变化,研究凝灰质砂岩溶蚀作用机理,为优质储层预测提供科学依据。     

师专物理实验教学中存在的问题及阶段性实验教学的构想

在分析师专物理实验教学中存在问题的基础上,提出了阶段性实验教学的设想。