Nonlinear analysis, design, and implementation of a VCO in S frequency band

A VCO in S frequency band is designed by using nonlinear technique based on large signal model of semiconductor devices. The nonlinear circuit of the VCO is analyzed by a novel analytical approach of harmonic balance method as an autonomous circuit, and with fulfilling the stability condition of the network, the output specifications are determined. This proposed nonlinear approach for determining of the frequency and amplitude stability is also based on harmonic balance method. The results of the analysis are compared with those of measurements. The comparison shows good agreement between results of this analytical approach and the measurements. Zahra Ghanian was born in Tehran, Iran, in 1975. She received the B.Sc. degree in electrical engineering from Sharif University of Technology, Tehran, Iran, in 1998, and the M.Sc. degree from the Amirkabir University of Technology, Tehran, Iran, in 2001. Since 2000, she has been involved in several research and engineering projects at the Amirkabir University of Technology, Iran Telecommunications Research Center (ITRC) and Niroo Research Institute (NRI). Her main areas of interest are design, simulation and analysis of circuits for Microwave, Millimeter wave and Wireless applications. Abdolali Abdipour was born in Iran in 1966. He obtained his B.Sc. in Electrical Engineering from Tehran University, Tehran, Iran in 1989, and the M.Sc. in Electronics from Limoges University, Limoges, France in 1992. Then he achieved his PhD degree in Electronic Engineering from Paris XI University, Paris, France in March 1996. His research areas include wireless communication systems (RF Technology and Transceivers), RF/Microwave/mm-wave circuit and system design, E & M modeling of active devices and circuits, high frequency electronics (signal and noise), nonlinear modeling and analysis of microwave devices and circuits. He has published over 80 papers in the refereed journals and international conferences. He authored two books “Noise in Electronic Communication: Modeling, Analysis and measurement” and “Transmission Lines” (in Persian). He is currently an associate professor of Electrical Engineering Department at Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran. Ayaz Ghorbani received PG diploma, m. Phiel and PhD degrees from the university of Bradford U.K. in 1984, 1985 and 1987 respectively in the area of electrical and communication engineering. From 1987 up to now he has been teaching various courses in the department of electrical engineering at university of Amirkabir (Tehran poly technique) Tehran, Iran. In 1987 he was awarded John Robertshaw Travel Award to visit a number of research establishments in the United States of America from Bradford University, and in 1990 he was also awarded U.R.S.I. Young Scientists Award at general assembly of the URSI, Prague, Czech Republic. In 2004 he was in Bradford University for one year as a research visitor where he obtained post doctorate degree. Dr. Ghorbani is author and coauthor of more than seventy papers in conferences as well as scientific journals.     

Fabrication and characterization of two-color midwavelength/long wavelength HgCdTe infrared detectors

High-performance 20-μm unit-cell two-color detectors using an n-p⁺-n HgCdTe triple-layer heterojunction (TLHJ) device architecture grown by molecular beam epitaxy (MBE) on (211)-oriented CdZnTe substrates with midwavelength (MW) infrared and long wavelength (LW) infrared spectral bands have been demonstrated. Detectors with nominal MW and LW cut-off wavelengths of 5.5 μm and 10.5 μm, respectively, exhibit 78 K LW performance with >70 % quantum efficiency, reverse bias dark currents below 300 pA, and RA products (zero field of view, 150-mV bias) in excess of 1×10³ Ωcm². Temperature-dependent current-voltage (I–V) detector measurements show diffusion-limited LW dark current performance extending to temperatures below 70 K with good operating bias stability (150 mV ± 50 mV). These results reflect the successful implementation of MBE-grown TLHJ detector designs and the introduction of advanced photolithography techniques with inductively coupled plasma (ICP) etching to achieve high aspect ratio mesa delineation of individual detector elements with benefits to detector performance. These detector improvements complement the development of high operability large format 640×480 and 1280×720 two-color HgCdTe infrared focal plane arrays (FPAs) to support third generation forward looking infrared (FLIR) systems.     

0.13μm射频MOS场效应晶体管特性及模拟

采用0.13μm CMOS射频和混合信号工艺进行了射频nMOS场效应晶体管版图的优化设计和芯片制作.对制作的射频nMOS器件进行了直流特性和S参数测试,测试结果表明射频nMOS管的特征频率fT达到了93GHz,fmax超过了90GHz.采用小信号等效电路模型对该nMOS管的交流特性进行了模拟.在100MHz到30GHz频率范围内得到了与测试结果相吻合的仿真结果.     

Hybrid routing in ad hoc networks with a dynamic virtual backbone

Virtual backbone routing (VBR) is a scalable hybrid routing framework for ad hoc networks, which combines local proactive and global reactive routing components over a variable-sized zone hierarchy. The zone hierarchy is maintained through a novel distributed virtual backbone maintenance scheme, termed the distributed database coverage heuristic (DDCH), also presented in this paper. Borrowing from the design philosophy of the zone routing protocol, VBR limits the proactive link information exchange to the local routing zones only. Furthermore, the reactive component of VBR restricts the route queries to within the virtual backbone only, thus improving the overall routing efficiency. Our numerical results suggest that the cost of the hybrid VBR scheme can be a small fraction of that of either one of the purely proactive or purely reactive protocols, with or without route caching. Since the data routes do not necessarily pass through the virtual backbone nodes, traffic congestion is considerably reduced. Yet, the average length of the VBR routes tends to be close to optimal. Compared with the traditional one-hop hierarchical protocols, our results indicate that, for a network of moderate to large size, VBR with an optimal zone radius larger than one can significantly reduce the routing traffic. Furthermore, we demonstrate VBR's improved scalability through analysis and simulations.     

How Multirobot Systems Research will Accelerate our Understanding of Social Animal Behavior

Our understanding of social insect behavior has significantly influenced artificial intelligence (AI) and multirobot systems' research (e.g., ant algorithms and swarm robotics). In this work, however, we focus on the opposite question: "How can multirobot systems research contribute to the understanding of social animal behavior?" As we show, we are able to contribute at several levels. First, using algorithms that originated in the robotics community, we can track animals under observation to provide essential quantitative data for animal behavior research. Second, by developing and applying algorithms originating in speech recognition and computer vision, we can automatically label the behavior of animals under observation. In some cases the automatic labeling is more accurate and consistent than manual behavior identification. Our ultimate goal, however, is to automatically create, from observation, executable models of behavior. An executable model is a control program for an agent that can run in simulation (or on a robot). The representation for these executable models is drawn from research in multirobot systems programming. In this paper we present the algorithms we have developed for tracking, recognizing, and learning models of social animal behavior, details of their implementation, and quantitative experimental results using them to study social insects.     

Effect of parameters of Ge(Si)/Si(001) self-assembled islands on their electroluminescence at room temperature

The electroluminescence (EL) of multilayered p-i-n structures with the self-assembled Ge(Si)/Si(001) islands are investigated. It is found that the structures with islands grown at 600°C have the highest intensity of the electroluminescence signal at room temperature in the wavelength range of 1.3–1.55 μm. The annealing of structures with the Ge(Si) islands leads to an increase in the EL-signal intensity at low temperatures and hampers the temperature stability of this signal, which is related to the additional Si diffusion into islands during annealing. The found considerable increase in the electroluminescence-signal intensity with the thickness of the separating Si layer is associated with a decrease in the elastic stresses in the structure with an increase in this layer’s thickness. The highest EL quantum efficiency in the wavelength range of 1.3–1.55 μm obtained in investigated structures amounted to 0.01% at room temperature.     

Nonlinear Modeling of the Dynamic Effects of Infused Insulin on Glucose: Comparison of Compartmental With Volterra Models

This paper presents the results of a computational study that compares simulated compartmental (differential equation) and Volterra models of the dynamic effects of insulin on blood glucose concentration in humans. In the first approach, we employ the widely accepted ldquominimal modelrdquo and an augmented form of it, which incorporates the effect of insulin secretion by the pancreas, in order to represent the actual closed-loop operating conditions of the system, and in the second modeling approach, we employ the general class of Volterra-type models that are estimated from input-output data. We demonstrate both the equivalence between the two approaches analytically and the feasibility of obtaining accurate Volterra models from insulin-glucose data generated from the compartmental models. The results corroborate the proposition that it may be preferable to obtain data-driven (i.e., inductive) models in a more general and realistic operating context, without resorting to the restrictive prior assumptions and simplifications regarding model structure and/or experimental protocols (e.g., glucose tolerance tests) that are necessary for the compartmental models proposed previously. These prior assumptions may lead to results that are improperly constrained or biased by preconceived (and possibly erroneous) notions-a risk that is avoided when we let the data guide the inductive selection of the appropriate model within the general class of Volterra-type models, as our simulation results suggest.     

Project Pathogens: The Anatomy of Omission Errors in Construction and Resource Engineering Project

Construction and engineering projects are typically complex in nature and are prone to cost and schedule overruns. A significant factor that often contributes to these overruns is rework. Omissions errors, in particular, have been found to account for as much as 38% of the total rework costs experienced. To date, there has been limited research that has sought to determine the underlying factors that contribute to omission errors in construction and engineering projects. Using data derived from 59 in-depth interviews undertaken with various project participants, a generic systemic causal model of the key factors that contributed to omission errors is presented. The developed causal model can improve understanding of the archetypal nature and underlying dynamics of omission errors. Error management strategies that can be considered for implementation in projects are also discussed.     

Low-power reduced transistor image sensor

An image sensor comprising an array of 128 by 50 super pixels, column parallel current conveyors and global difference double sampling (DDS) unit is presented. The super pixel consists of: a reset transistor, a readout transistor, four transfer transistors and four photodiodes. The photo pixel address switch is placed outside the pixel, effectively implementing 1.5 transistors per pixel using a sharing scheme of the readout and reset transistor. The column FPN of 0.43% from saturated level and SNR of 43.9 dB is measured. The total power consumption is 5 mW at 30 frame/s.     

台达BW系列变频器在电池极片轧辊机收放卷上的应用

本文主要介绍台达BW系列变频器在电池机片轧辊机收放卷上的应用,利用台达BW系列变频器特有的收放卷功能,达到在金属物料在收放卷的恒张力控制。