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Dynamic Trajectory Generation for Spatially Constrained Mechanical Systems Using Harmonic Potential Fields
Get PDFThe harmonic potential field (HPF) approach to motion planning is shown to provide an efficient and provably-correct basis for building intelligent, context-sensitive, and goal-oriented controllers. In the paper by the author (2006) a novel type of dampening forces called: nonlinear, anisotropic, dampening forces (NADFs) are used to convert the guidance signal from an HPF into a navigation control signal with verifiable capabilities. This work provides two extensions of the NADF approach. The first is a blind, iterative procedure that can totally cancel the steady state error. The other extension is concerned with the nonholonomic case. Theoretical developments and simulation results are provided
High Speed Hardware Architecture to Compute GF(p) Montgomery Inversion with Scalability Features
Get PDFModular inversion is a fundamental process in several cryptographic systems. It can be computed in software or hardware, but hardware computation has been proven to be faster and more secure. This research focused on improving an old scalable inversion hardware architecture proposed in 2004 for finite field GF(p). The architecture comprises two parts, a computing unit and a memory unit. The memory unit holds all the data bits of computation whereas the computing unit performs all the arithmetic operations in word (digit) by word bases such that the design is scalable. The main objective of this paper is to show the cost and benefit of modifying the memory unit to include shifting, which was previously one of the tasks of the scalable computing unit. The study included remodeling the entire hardware architecture removing the shifter from the scalable computing part and embedding it in the non-scalable memory unit instead. This modification resulted in a speedup to the complete inversion process with an area increase due to the new memory shifting unit. Several design schemes have been compared giving the user the complete picture to choose from depending on the application need
Theoretical Analysis of Magnetically switchable shorted patch antenna
Get PDFSwitchable magnetic media and shorting posts are popular in controlling the radiation characteristics and the size of microstrip antennas or array. In this paper, a ferrite based shorted patch antenna is designed to demonstrate magnetically switchable frequency response. Simulated resonance and radiation responses of the probe feed antenna revealed improved impedance bandwidth, antenna size reduction, tunable and non-tunable switched resonance and low biasing requirement for switching the antenna
Failure Rate Analysis of Boeing 737 Brakes Employing Neural Network
Get PDFThe failure rate analysis of brake assemblies of a commercial airplane, i.e., Boeing 737, is analyzed using the artificial neural network and Weibull regression models. One-layered feed-forward back-propagation algorithm for artificial neural network whereas three parameters model for Weibull are used for the analysis. Three years of data are used for model building and validation. The results show that the failure rate predicted by neural network is closer in agreement with the actual data than the failure rate predicted by the Weibull model. Results also indicate that neural network can be effectively integrated into an aviation maintenance facility computerized material requirement planning system to forecast the number of brake assemblies needed for a given planning horizon
Large signal performance of micromachined silicon inductive microphones
Get PDFA mathematical model for the open-circuit output voltage of a micromachined silicon inductive microphone is presented. The model, basically a sine-series function, can easily yield closed-form expressions for the amplitudes of the output components resulting from a multisinusoidal input acoustic pressure. The special case of an equal-amplitude two-tone acoustic pressure input is considered in detail. The results show that, the microphone generates both even and odd-order harmonic and intermodulation products
A Stable Time-Domain Beam Propagation Method for Modeling Ultrashort Optical Pulses
No full textA new technique to model ultrashort optical pulses is proposed and verified. The technique uses Pade approximant to account for the fast pulse propagational variations. Numerical parameters of the technique have been tested and it was shown that the method is simple, very stable, and accurate in modeli ng ultrashort optical pulses in long propagation interaction
Message Concealment Techniques using Image based Steganography
Get PDFImage based steganography is the most popular method for message concealment. In this paper, two techniques are proposed for enhancing the message secrecy using image based steganography. The first technique is based on the use of punctuation marks to encode a secret message before embedding it into the image file. The second technique is based on the use of modified scytale cipher to hide a secret message in an image file. Both of these techniques have been implemented and tested using the S-Tools software package. The original and stego-images both are shown for the purpose of compariso
Throughput and Delay Analysis of Interrupt-Driven Kernels under Poisson and Bursty Traffic
Get PDFThis paper studies the performance of interrupt-driven kernels when subjected to heavy network traffic such as that of Gigabit Ethernet. Under heavy network traffic, the kernel performance will be negatively affected due to interrupt overhead caused by the incoming traffic. In particular, excessive latency and significant degradation in system throughput can be experienced. In this paper, we present analytical models to study the performance in terms of two key kernel performance metrics: throughput and delay. The performance is also studied using simulation. Both Poisson and bursty traffic with empirical packet size distribution are considered
An Analysis Method for Inertial Particle Separator
Get PDFThe paper describes an analysis method for an inertial particle separator (IPS) system modeled as a multi-element airfoil configuration. The analysis method is implemented in a numerical tool that is able to perform impingement analysis using spherical, non-spherical particles as well as water droplets for a range of Reynolds number (10-4 ≤ Re ≤ 5×105). A limitations of the analysis tool is that it lacks an appropriate particle rebound model for the treatment of particle-wall collisions. The usefulness of the analysis tool is its use in conjunction with a multipoint inverse design tool for the design of multi-element airfoil based IPS system model in an inverse fashion as opposed to the direct design methods being employed currently for this task. With such a design and analysis tool at hand, the design space can be explored as well as trade-off studies can be performed that can aid in the development of a more efficient design methodology for multi-element airfoil based IPS systems