Aspects of the design of low noise, negative resistance, reflectionmode transistor amplifiers

The authors consider the use of microwave transistors in the negative resistance reflection mode and present the conditions for optimum noise performance. Possible advantages include the possibility of higher gain in the millimeter-wave region, which can be achieved by absorbing the parasitic common lead inductance into the feedback circuit designed to generate the negative resistance, and the existence of a failsafe mode of operation, in that the failure of the active device or its power supply is likely to lead a low return loss, resulting in a small insertion loss through the amplifiers, which may permit continued, although degraded, system operation. The latter potential advantage has proved to be of interest to radar system designers     

明明白白选择晶振

振荡器就像电子系统中的电源一样无处不在,有人认为它们的重要性等同于电源,在任何需要时序信号的应用中都能发现它们,从数字手表到电视和PC。由于它们在电子设备时序中扮演重要角色,它们的失效会导致整个系统的故障。例如,调查人员通过分析1972年美国加州Fremont火车撞车事故,发现起因是一块控制板上的晶振故障。     

Primitive polynomials of degree 301 through 500

This letter is an extension of the table of minimal weight primitive polynomials found in [1].     

Literal solutions for time-domain crosstalk on losslesstransmission lines

The transmission line equations for a three-conductor lossless line in a homogeneous medium are solved in literal (symbolic) form in the time domain. The resulting formulas for the crosstalk voltages are exact and are given in terms of the line parameters and the termination impedances. These formulas demonstrate the effect of the various line parameters on the resulting crosstalk and show how to adjust the line parameters to achieve a desired time-domain crosstalk. In addition, other solution methods are discussed and used to verify the literal solution     

Semiconductor device reliability vs process quality

This paper describes a method for defining a quantitative model relating “quality” expressed in terms of parameter distributions and “reliability” expressed in terms of failure rates. This model makes it possible to generate a more realistic failure rate estimate for semiconductor devices. With this model, failure rate predictions based on conventional life test data and on process parameter distributions, can be defined.     

Development, implementation, and testing of fault detection strategies on the National Wind Technology Center’s controls advanced research turbines

The National Renewable Energy Laboratory’s National Wind Technology Center dedicates two 600 kW turbines for advanced control systems research. A fault detection system for both turbines has been developed, analyzed, and improved across years of experiments to protect the turbines as each new controller is tested. Analysis of field data and ongoing fault detection strategy improvements have resulted in a system of sensors, fault definitions, and detection strategies that have thus far been effective at protecting the turbines. In this paper, we document this fault detection system and provide field data illustrating its operation while detecting a range of failures. In some cases, we discuss the refinement process over time as fault detection strategies were improved. The purpose of this article is to share field experience obtained during the development and field testing of the existing fault detection system, and to offer a possible baseline for comparison with more advanced turbine fault detection controllers.     

Establishment of a dynamic model for the p-Ge far IR laser

Using new experimental data from modeling the p-Ge laser pulse plus literature data, basic laser parameters are obtained so that one can solve the laser equations of Pantell and Puthoff to obtain formulas for calculating all laser quantities of interest. Values, calculated using the formulas, such as gain, saturation intensity, pump population differences, power generated, output coupling, efficiency, etc. are in excellent agreement with available experimental data. This work contributes to problems in determining laser line transitions, the laser cycle, and the optimization of the laser performance.     

Extended-Hungarian-JPDA: exact single-frame stem cell tracking

The fields of bioinformatics and biotechnology rely on the collection, processing and analysis of huge numbers of biocellular images, including cell features such as cell size, shape, and motility. Thus, cell tracking is of crucial importance in the study of cell behaviour and in drug and disease research. Such a multitarget tracking is essentially an assignment problem, NP-hard, with the solution normally found in practice in a reduced hypothesis space. In this paper we introduce a novel approach to find the exact association solution over time for single-frame scan-back stem cell tracking. Our proposed method employs a class of linear programming optimization methods known as the Hungarian method to find the optimal joint probabilistic data association for nonlinear dynamics and non-Gaussian measurements. The proposed method, an optimal joint probabilistic data association approach, has been successfully applied to track hematopoietic stem cells.     

Surface-constrained volumetric brain registration using harmonic mappings

In order to compare anatomical and functional brain imaging data across subjects, the images must first be registered to a common coordinate system in which anatomical features are aligned. Intensity-based volume registration methods can align subcortical structures well, but the variability in sulcal folding patterns typically results in misalignment of the cortical surface. Conversely, surface-based registration using sulcal features can produce excellent cortical alignment but the mapping between brains is restricted to the cortical surface. Here we describe a method for volumetric registration that also produces an accurate one-to-one point correspondence between cortical surfaces. This is achieved by first parameterizing and aligning the cortical surfaces using sulcal landmarks. We then use a constrained harmonic mapping to extend this surface correspondence to the entire cortical volume. Finally, this mapping is refined using an intensity-based warp. We demonstrate the utility of the method by applying it to T1-weighted magnetic resonance images (MRIs). We evaluate the performance of our proposed method relative to existing methods that use only intensity information; for this comparison we compute the intersubject alignment of expert-labeled subcortical structures after registration.     

应用于暂时粘结、基片保护和MOEMS封装的新型材料

随着微电子制造商持续缩小晶体管基极和其他元件的尺寸,集成电路的密度不断增大,电路连接工艺中开始使用低k介电质和铜导电体。为了进一步提高电路整体性能与射电频率性能、缩小体积、降低电源损耗、提高散热效率,承载电路的基片的厚度正在持续变薄。常规的工艺已经无法加工先进的超薄基片。为了解决这个工艺中的难题,BrewerScience利用自己先进的材料、工艺、机械设备的研究开发水平,正在开发一套崭新的超薄基片的加工操作流程。介绍用于将超薄基片暂时粘结到另一载体的系列材料和流程,完成加工以后,基片和载体可以很容易地分离。另外,对用于保护基片的新型涂料也进行了介绍。在对基片进行薄化和切割的时候,这种涂料可以对基片提供有效的保护。最后,介绍了高透明高折射材料,这些材料用在高亮度发光二极管(HB-LED)和微光电机械系统(MOEMS)中,可以降低由封装引起的光损耗。