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1.
 吉尔伯特·牛顿·路易斯是20世纪最伟大的化学家之一。他因在发展热力学理论并将其应用于实际化学系统方面做出了重大贡献,被认为是现代化学热力学奠基人;因其提出的共价键和电子对概念促成现代化学键理论的产生,被认为是共价键发现者;他提出的酸碱概念是对化学科学的另一个重要的贡献。路易斯曾41次获得诺贝尔化学奖提名,但从未获奖,这也成为诺贝尔奖历史上的巨大争议之一。介绍了路易斯的人生经历和科学成就,盘点了其科学探索的历程。  相似文献   
2.
AAL2是为了满足对时延敏感的低速率或可变速率的短分组业务需求而提出的一种组合信元ATM适配技术,在战术通信网中也得到了应用。利用Gilbert信道模型分析了在战术环境下标准ATM信元结构AAL2 CPS分组的丢失率性能。研究表明,在战术环境下为了保证端到端话音传输质量,应该采用一定的差错控制机制来保护AAL2信元。通过分析,比较了几种不同信元头差错保护机制下,无线ATM信元丢失率和不同前向差错控制方式下,AAL2 CPS分组的最大分组丢失率性能,从而推导出在突发信道环境下一种效率和可靠性均较高的战术AAL2信元结构及其差错控制机制。  相似文献   
3.
The epistemic problem of assessing the support that some evidence confers on a hypothesis is considered using an extended example from the history of meteorology. In this case, and presumably in others, the problem is to develop techniques of data analysis that will link the sort of evidence that can be collected to hypotheses of interest. This problem is solved by applying mathematical tools to structure the data and connect them to the competing hypotheses. I conclude that mathematical innovations provide crucial epistemic links between evidence and theories precisely because the evidence and theories are mathematically described.  相似文献   
4.
In De magnete (1600), Gilbert frequently appealed to diagrams. As result of a focus on the experimental methodology of the treatise, its diagrammatic dimension has been overlooked in the scholarship. This paper argues that, in De magnete, at least some diagrams are epistemically relevant; specifically, Gilbert moves from experiments to concepts and theories through diagrams. To show this, I analyze the role that the “Diagram of motions in magnetick orbes” plays in the formulation of Gilbert's rule of alignment of magnetic bodies within the orb of virtue (the space around a magnet where its influence is exerted). If it turns out that diagrams play a genuine role in Gilbert's magnetic investigations, then his investigative strategy goes beyond mere experimentalism.  相似文献   
5.
基于吉尔伯特型的CMOS射频混频器的设计   总被引:1,自引:0,他引:1  
采用多晶电阻作为输出负载、开关对的源极注入电流、共源节点串联电感、驱动级的源简并阻抗方法,提出了一种新型的双通道正交混频器,并采用Candence完成了电路设计.仿真结果表明:在电源电压为1.8V,本振信号输入功率为3 dBm的时,混频器在1 MHz中频处的单边带噪声系数为7.47 dB,在100 kHz中频处为9.35 dB,在10 kHz中频处为16.39 dB;变频增益降为8.46 dB.提高了线性度,且其三阶交调点为8.42 dBm.  相似文献   
6.
基于H.264的数据分割和不等差错保护方案   总被引:1,自引:0,他引:1  
为改善H.264码流在无线信道中传输的误码鲁棒性,提出一种新的数据分割抗误码方案.该方案利用无线信道反馈信息,预测信道丢包率,并判决对视频编码层(VCL)的数据是否进行数据分割.在高误码环境下,采用码率自适应删余卷积码(rate-compatible punctured convolution code)对分割后的数据区进行不等差错保护.仿真表明,算法具有较好的抗误码鲁棒性,有效地降低编码冗余,提高了编码效率.  相似文献   
7.
The wave-mechanical treatment of the valence bond, by Walter Heitler and Fritz London, and its ensuing foundational importance in quantum chemistry has been traditionally regarded as the basis for the argument that chemistry may be theoretically reduced to physics. Modern analyses of the reductionist claim focuses on the limitations to achieving full reduction in practice because of the approximations used in modern quantum chemical methods, but neglect the historical importance of the chemical bond as a chemical entity. This paper re-examines these arguments with a study of the development of the valence bond by chemist Gilbert Lewis within a chemically autonomous framework, and its extension by Linus Pauling using Heitler and London’s methods. Here, we see that the chemical bond is best described as a theoretical synthesis or physico-chemical entity, to represent its full interdisciplinary importance from the philosophical and historical perspectives.  相似文献   
8.
A low power quadrature up-conversion mixer for WSN application   总被引:1,自引:0,他引:1  
This paper presents an up-conversion mixer for 2.4GHz wireless sensor networks in 0. 181xm RF complementary metal-oxide semiconductor (CMOS) technology. It is based on a double-balanced Gilbert cell type. With two Gilbert cells it was applied quadrature modulation. Operational ampli- tiers are used in this design to improve the conversion gain under low power consumption. The mixer design is based on 0.18txm RF CMOS process. And the mixer test results indicate that under 1.8V power supply, with input frequency 2.4 - 2.4835GHz, the conversion voltage gain is 1.2 - 2dB. When the output frequency is 2.4GHz, its power gain is -4.46dB, and its input referred 1 dB com- pression point is -11.5dBm and it consumes 1.77mA current.  相似文献   
9.
准噶尔盆地西北缘中三叠统克拉玛依上亚组为非常规资源主力储集层,厘清其沉积相特征和识别建立沉积模式对指导该地区的非常规资源勘探具有重要意义。通过对吐孜阿克内沟地区露头剖面进行详细观察和精细测量,在克拉玛依上亚组利用露头直观性划分出石炭系、克拉玛依上亚组与侏罗系八道湾组地层界限,并详细分析了沉积构造特征、粒度特征、沉积相类型及演化规律。结果表明:研究区克拉玛依上亚组存在滨浅湖吉尔伯特型扇三角洲沉积的证据。克拉玛依上亚组岩石粒度下部较细,向上部逐渐变粗,具明显的三层结构(顶积层、前积层、底积层);研究区主要发育扇三角洲平原、扇三角洲前缘和前扇三角洲,进一步划分出辫状河道与河道间、水下分流河道、水下分流河道间与前缘沙坝、前三角洲泥等沉积微相。通过对克拉玛依上亚组顶部露头实测,识别出9个单层组,明确了沉积相在横向空间的变化及砂体展布规律,建立了该区滨浅湖吉尔伯特型扇三角洲沉积模式。  相似文献   
10.
为解决模糊控制器电路设计中的去模糊运算问题,提出了一种数模混合电路实现的模糊控制器去模糊运算单元电路设计。通过对折叠型G ilbert乘法器电路作适当的扩展,提出了多路乘法器的设计,实现了多个输入电压与一个共同的乘数电压的乘法运算,并应用该多路乘法器和运算放大器设计了归一化激活度计算电路。应用归一化激活度计算电路和加权求和电路组成了该新结构的去模糊单元电路。采用无锡上华0.6μm混合信号工艺参数设计完成。H sp ice模拟结果表明该单元电路可以完成去模糊运算工作,并作为子单元电路应用于模糊控制器的VLS I实现。  相似文献   
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