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Articles 1 - 16 of 16
Full-Text Articles in Computer Engineering
Simulation & Analysis Of Liquid Metal Conical Helical Antenna, Zhou Yun, Shaojun Fang, Shiqiang Fu, Zhongbao Wang
Simulation & Analysis Of Liquid Metal Conical Helical Antenna, Zhou Yun, Shaojun Fang, Shiqiang Fu, Zhongbao Wang
Journal of System Simulation
Abstract: In order to replace the solid metal antenna, a novel liquid metal conical helical antenna was presented. The antenna is easy to adjust its shape. The circularly polarized antenna has the characteristics of small size, high gain, wide bandwidth, and it is easy to reconstruct. Taking maritime satellite communications as an example, the proposed antenna was designed, simulated and optimized for antenna impedance matching with HFSS software, and a good circularly polarized radiation and impedance characteristics for the antenna were obtained. The simulated results show that: in the entire maritime satellite communication work band (1 525-1 660.5 …
A Novel Microstrip Diplexer Design With Tunable Bandwidths And Switchable Channels For 4.5g Applications, Ali̇ Kürşad Görür, Pinar Öztürk Özdemi̇r, Eli̇f Güntürkün Şahi̇n, Ceyhun Karpuz
A Novel Microstrip Diplexer Design With Tunable Bandwidths And Switchable Channels For 4.5g Applications, Ali̇ Kürşad Görür, Pinar Öztürk Özdemi̇r, Eli̇f Güntürkün Şahi̇n, Ceyhun Karpuz
Turkish Journal of Electrical Engineering and Computer Sciences
In this paper, a novel microstrip diplexer with tunable bandwidths and switchable channels is presented by using dual-mode square loop resonators (DMSLRs). Two resonators at different electrical lengths are coupled to input and output ports with lumped capacitors, and the isolation between the output ports is optimized by means of these capacitors. In order to obtain tunable bandwidth in each channel, varactor diodes are located at the orthogonal corners of the proposed resonators. In addition, the proposed resonators have reference patch elements at the lateral arms to provide convenience of varactor diode capacitances, such as perturbation elements. Depending on the …
Generalizing Effective Spatial Bandwidth For Pole Location In Mas: The Elliptic Cylinder, James Richie
Generalizing Effective Spatial Bandwidth For Pole Location In Mas: The Elliptic Cylinder, James Richie
Electrical and Computer Engineering Faculty Research and Publications
The location of poles in the method of auxiliary sources for 2-D scatterers can be assisted using the effective spatial bandwidth (EBW) of the incident and scattered fields. Previously, only circular boundaries were considered. Here, EBW is extended to noncircular boundaries. Calculations presented for a cylinder with elliptical cross section verify EBW as an additional tool for pole placement for more general geometries.
Cloud Computing, Contractibility, And Network Architecture, Christopher S. Yoo
Cloud Computing, Contractibility, And Network Architecture, Christopher S. Yoo
All Faculty Scholarship
The emergence of the cloud is heightening the demands on the network in terms of bandwidth, ubiquity, reliability, latency, and route control. Unfortunately, the current architecture was not designed to offer full support for all of these services or to permit money to flow through it. Instead of modifying or adding specific services, the architecture could redesigned to make Internet services contractible by making the relevant information associated with these services both observable and verifiable. Indeed, several on-going research programs are exploring such strategies, including the NSF’s NEBULA, eXpressive Internet Architecture (XIA), ChoiceNet, and the IEEE’s Intercloud projects.
Cloud Computing: Architectural And Policy Implications, Christopher S. Yoo
Cloud Computing: Architectural And Policy Implications, Christopher S. Yoo
All Faculty Scholarship
Cloud computing has emerged as perhaps the hottest development in information technology. Despite all of the attention that it has garnered, existing analyses focus almost exclusively on the issues that surround data privacy without exploring cloud computing’s architectural and policy implications. This article offers an initial exploratory analysis in that direction. It begins by introducing key cloud computing concepts, such as service-oriented architectures, thin clients, and virtualization, and discusses the leading delivery models and deployment strategies that are being pursued by cloud computing providers. It next analyzes the economics of cloud computing in terms of reducing costs, transforming capital expenditures …
Sensitivity Of High-Speed Lightwave System Receivers Using Inalas Avalanche Photodiodes, Daniel S.G. Ong, Majeed M. Hayat, John P.R. David, Jo Shien Ng
Sensitivity Of High-Speed Lightwave System Receivers Using Inalas Avalanche Photodiodes, Daniel S.G. Ong, Majeed M. Hayat, John P.R. David, Jo Shien Ng
Electrical and Computer Engineering Faculty Research and Publications
Calculations based on a rigorous analytical model are carried out to compare the sensitivity of optical receivers that use InP and In0.52Al0.48As avalanche photodiodes (APDs). The model includes the effects of intersymbol interference, tunneling current, avalanche noise and its correlation with the stochastic avalanche duration, dead space, and transimpedance amplifier noise. For a 10-Gb/s system with a bit-error rate of 10-12, the optimum receiver sensitivity predicted for In0.52Al0.48As and InP APDs is -28.6 and -28.1 dBm, respectively, corresponding to a reduction of 11% in optical signal power for receivers using …
The Changing Patterns Of Internet Usage, Christopher S. Yoo
The Changing Patterns Of Internet Usage, Christopher S. Yoo
Federal Communications Law Journal
Symposium: Essays from Time Warner Cable's Research Program on Digital Communications.
The Challenge Of Increasing Broadband Capacity, Dale N. Hatfield
The Challenge Of Increasing Broadband Capacity, Dale N. Hatfield
Federal Communications Law Journal
Symposium: Essays from Time Warner Cable's Research Program on Digital Communications.
5 Ghz Band Vehicle-To-Vehicle Channels: Models For Multiple Values Of Channel Bandwidth, Qiong Wu, David W. Matolak, Indranil Sen
5 Ghz Band Vehicle-To-Vehicle Channels: Models For Multiple Values Of Channel Bandwidth, Qiong Wu, David W. Matolak, Indranil Sen
Faculty Publications
In Sen and Matolak's earlier paper, 5-GHz-band vehicle-to-vehicle (V2V) channel models were presented for channel bandwidths of 5 and 10 MHz. In this paper, we provide additional tapped delay line models for bandwidths of 1, 20, 33.33, and 50 MHz based upon the data used in Sen and Matolak's paper. We provide tables of channel parameters for five types of V2V channel classes and also include example tap correlation coefficients. Root-mean-square delay spread values are summarized, as are values of bandwidth for which the channel frequency correlation takes values of 0.7 and 0.5. As with the results from Sen and …
The Changing Patterns Of Internet Usage, Christopher S. Yoo
The Changing Patterns Of Internet Usage, Christopher S. Yoo
All Faculty Scholarship
The Internet unquestionably represents one of the most important technological developments in recent history. It has revolutionized the way people communicate with one another and obtain information and created an unimaginable variety of commercial and leisure activities. Interestingly, many members of the engineering community often observe that the current network is ill-suited to handle the demands that end users are placing on it. Indeed, engineering researchers often describe the network as ossified and impervious to significant architectural change. As a result, both the U.S. and the European Commission are sponsoring “clean slate” projects to study how the Internet might be …
Application Of Ict - I: Using Point-To-Point 1550nm Laser For Outdoor Mobility, Roshan A. Shaikh, Abdul Basit
Application Of Ict - I: Using Point-To-Point 1550nm Laser For Outdoor Mobility, Roshan A. Shaikh, Abdul Basit
International Conference on Information and Communication Technologies
Significant implementation challenges exist in wireless backbone connectivity. Typical optical wireless communication topologies are evaluated. A fresh approach using 1550nm Wavelength laser to design protocol and topology for point-to-point outdoor connectivity is carried out. Matlab simulation results support the 1550nm laser as a good choice for outdoor connectivity for optical wireless communication. New design and topology for an optical wireless communication system is suggested with special consideration of security and recommendation for the optimal use of such a technology is suggested.
Networks - I: Networks-On-Chip: Challenges, Trends And Mechanisms For Enhancements, Omer Tayan
Networks - I: Networks-On-Chip: Challenges, Trends And Mechanisms For Enhancements, Omer Tayan
International Conference on Information and Communication Technologies
The rate of increase of silicon capacity in integrated circuits (IC) will enable system integration of several billion transistors to reside on a single chip in the near future. Future system-on-chip (SoC) systems must therefore integrate up to several hundreds of cores within a single chip, and SoC designs will employ on-chip communication networks (NoCs) as a result. This paper discusses the problems with many current SoC systems, surveys the challenges and trends facing future SoC designs and proposes a mechanism for enhancing NoC strategies of the future by enhancing memory management and utilization techniques within an NoC.
Networks - I: An Instantiation Of Way Point Routing For Mobile Ad Hoc Networks, Waseem M. Arain, Sayeed Ghani
Networks - I: An Instantiation Of Way Point Routing For Mobile Ad Hoc Networks, Waseem M. Arain, Sayeed Ghani
International Conference on Information and Communication Technologies
Mobile ad hoc networks are increasingly finding their existence in the marketplace heading to a new paradigm of pervasive computing. However there are many areas open to research in the field. Due to node mobility resulting in an ever-changing network topology, conventional routing methods cannot be applied in MANETS. Therefore, this is one of the core areas of research. Researchers are challenged to design protocols that can potentially scale to anything from thousand to tens of thousands of nodes and to reduce the route discovery latency. In this paper a different instantiation of way point routing (WPR) model is proposed, …
Statistical Correlation Of Gain And Buildup Time In Apds And Its Effects On Receiver Performance, Peng Sun, Majeed M. Hayat, Bahaa E.A. Saleh, Malvin Carl Teich
Statistical Correlation Of Gain And Buildup Time In Apds And Its Effects On Receiver Performance, Peng Sun, Majeed M. Hayat, Bahaa E.A. Saleh, Malvin Carl Teich
Electrical and Computer Engineering Faculty Research and Publications
This paper reports a novel recurrence theory that enables us to calculate the exact joint probability density function (pdf) of the random gain and the random avalanche buildup time in avalanche photodiodes (APDs) including the effect of dead space. Such calculations reveal a strong statistical correlation between the gain and the buildup time for all widths of the multiplication region. To facilitate the calculation of the photocurrent statistics in the presence of this correlation, the impulse-response function of the APD is approximately modeled by a function of time whose prespecified shape is appropriately parameterized by two random variables: the gain …
Data Transmission Scheduling For Distributed Simulation Using Packet A, Juan Vargas-Morales
Data Transmission Scheduling For Distributed Simulation Using Packet A, Juan Vargas-Morales
Electronic Theses and Dissertations
Communication bandwidth and latency reduction techniques are developed for Distributed Interactive Simulation (DIS) protocols. Using logs from vignettes simulated by the OneSAF Testbed Baseline (OTB), a discrete event simulator based on the OMNeT++ modeling environment is developed to analyze the Protocol Data Unit (PDU) traffic over a wireless flying Local Area Network (LAN). Alternative PDU bundling and compression techniques are studied under various metrics including slack time, travel time, queue length, and collision rate. Based on these results, Packet Alloying, a technique for the optimized bundling of packets, is proposed and evaluated. Packet Alloying becomes more active when it is …
A New Approach For Computing The Bandwidth Statistics Of Avalanche Photodiodes, Majeed M. Hayat, Guoquan Dong
A New Approach For Computing The Bandwidth Statistics Of Avalanche Photodiodes, Majeed M. Hayat, Guoquan Dong
Electrical and Computer Engineering Faculty Research and Publications
A new approach for characterizing the avalanche-buildup-time-limited bandwidth of avalanche photodiodes (APDs) is introduced which relies on the direct knowledge of the statistics of the random response time. The random response time is the actual duration of the APD’s finite buildup-limited random impulse response function. A theory is developed characterizing the probability distribution function (PDF) of the random response time. Recurrence equations are derived and numerically solved to yield the PDF of the random response time. The PDF is then used to compute the mean and the standard deviation of the bandwidth. The dependence of the mean and the standard …