Design and performance evaluation of a state-space based AQM

Recent research has shown the link between congestion control in communication networks and feedback control system. In this paper, the design of an active queue management (AQM) which can be viewed as a controller, is considered. Based on a state space representation of a linearized fluid flow model of TCP, the AQM design is converted to a state feedback synthesis problem for time delay systems. Finally, an example extracted from the literature and simulations via a network simulator NS (under cross traffic conditions) support our study

Design and Performance Evaluation of Slotted Walls for Two-Dimensional Wind Tunnels

A procedure for designing slotted walls for two dimensional wind tunnels is is presented. The design objective is the minimization of blockage of streamline curvature or the reduction of both. The slotted wall boundary condition is derived both for flow from the tunnel into the plenum and vice versa, and the procedure for evaluating wall interference is described. A correlation of experimental data for the slotted wall boundary condition is given. Results are given for several designs and evaluations of slotted wind tunnel walls

Design and performance evaluation of turbo FDE receivers

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do Grau de Mestre em Engenharia Electrotécnica e de ComputadoresIn recent years, block transmission techniques were proposed and developed for broadband wireless communication systems, which have to deal with strongly frequency-selective fading channels. Techniques like Orthogonal Frequency-Division Multiplexing (OFDM)and Single Carrier with Frequency Domain Equalization (SC-FDE) are able to provide high bit rates despite the channel adversities. In this thesis we concentrate on the study of single carrier block transmission techniques considering receiver structures suitable to scenarios with strongly time-dispersive channels. CP-assisted (Cycle Pre x) block transmission techniques are employed to cope with frequency selective channels, allowing cost-e ective implementations through FFT-based (Fast Fourier Transform) signal processing. It is investigated the impact of the number of multipath components as well as the diversity order on the asymptotic performance of SC-FDE schemes. We also propose a receiver structure able to perform a joint detection and channel estimation method, in which it is possible to combine the channel estimates, based on training sequences, with decision-directed channel estimates. A study about the impact of the correlation factor estimation in the performance of Iterative Block-Decision Feedback Equalizer (IB-DFE) receivers is also presented

Design and Performance Evaluation of a Solar Dryer

One of the ways to combat food insecurity as world population rises is the reduction of food losses. Drying is one of the oldest methods of food preservation and hence reduces food losses. Solar drying uses energy from the sun and an absorber material to carry out drying of produce. In this project, a solar dryer was designed, constructed and its performance was evaluated. The dryer has overall dimensions of 1000mm by 410mm by 700mm. The inner part of the dryer compartment was lagged with aluminum foil to act as an insulator. The solar collector made of galvanized sheet and the glass on top of it have an area of 800mm by 380mm. Fresh scotch bonnet pepper was used as the produce of choice. The pepper was dried in 2 experiments for 3 weeks each. 200g of pepper was used and weighed to measure weight loss periodically. Temperature and humidity of the drying chamber and the surrounding were measured with data loggers throughout the periods of the experiments. The results showed that the ambient temperature during the experiments was higher than the temperature of the drying chamber in the early hours of the morning between 4am and 10am. During every other period, the temperature in the drying chambers was higher than the ambient temperature. An average moisture content of 81.3% w.b. was removed from the pepper during the experiments. The average efficiency of the dryer was 28.4%

Design study for LANDSAT D attitude control system

A design and performance evaluation is presented for the LANDSAT D attitude control system (ACS). Control and configuration of the gimballed Ku-band antenna system for communication with the tracking and data relay satellite (TDRS). Control of the solar array drive considered part of the ACS is also addressed

Design and Performance Evaluation of an Intelligent Star Tracker

Current state-of-the-art commercial star sensors typically weigh 15 pounds, attain 5 to 10 arcsecond accuracy, and use roughly 10 watts of power. Unfortunately, the current state-of-the-art commercial star sensors do not meet many of NASA’s “next-generation” spacecraft and instrument needs. Nor do they satisfy Air Force’s needs for micro/nano-satellite systems. In an effort to satisfy micro/nano satellite mission needs the Air Force Research Laboratory is developing an intelligent star Tracker, called IntelliStar, which incorporates several novel technologies including Silicon carbide optical housing, MEMs based adaptive optic technologies, smart active pixels, and algebraic coding theory. The design considerations associated with the development of the IntelliStar system are presented along with experimental results which characterize each technologies contribution to overall system performance. In addition to being light weight, the IntelliStar System offers advantages in speed, size, power consumption, and radiation tolerance

Design and performance evaluation of centrifugal cashew nut sheller

Cashew nut centrifugal shelling machine was designed and constructed. Shelling efficiency and whole kernel recovery was evaluated for hot-oil roasted nuts on the machine. The design was based on the principle of the optimum kinetic energy that could break the cashew nut shell. The deformation energy used was 4.8763 Joules. The angular velocity of the impeller calculated from the energy was 376.12 rad/s which was equal 3592 rpm. The motor power used was more than 917.34 Watts, the minimum power requirement. The prototype of cashew nut sheller was constructed and evaluated for its shelling efficiency and whole kernel recovery using three levels of moisture content (7.00%w.b., 8.46%w.b. and 9.83% w.b.), three levels of impeller speeds and three grades (large, medium and small) of nut sizes. The results showed that moisture content has significant effect (at P < 0.05) on the shelling efficiency and whole kernel recovery for all the grades of the nut. However, the impeller speed has significant effect on the whole kernel recovery of medium and small nuts. The predicted optimal values of the whole kernel recovery and shelling efficiency for large nut were 65.4% and 96.8% respectively at 3110rpm and 9.06w.b. For medium nut, they were 51.62% and 93.24% respectively at 3487rpm and 8.92w.b. For small nut, they were 37.95% and 92.56% respectively at 3487rpm and 9.83w.b

Design and performance evaluation of an improved mobile IP protocol

2003-2004 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Design and Performance Evaluation of Piezo-Driven Synthetic Jet Devices

In the last two decades synthetic jet actuators have gained much interest among flow control techniques due to their short response time, high jet velocity and absence of traditional piping, that matches the requirements of reduced size and low weight. A synthetic jet is generated by the diaphragm oscillation (generally driven by a piezo-electric element) in a relatively small cavity, producing periodic cavity pressure variations associated to cavity volume changes. The high pressure air exhausts through an orifice, converting membrane elastic energy in jet kinetic energy. This review paper faces the development of various lumped-element models (LEM) as practical tools to design and manufacturing actuators. LEM can predict quickly device performances such as frequency response in terms of membrane displacement, cavity pressure and jet velocity, as well as efficiency of energy conversion of input Joule power into useful kinetic power of air jet. Actuator performance is analyzed also by varying typical geometric parameters such as cavity height and orifice diameter and length, through a proper dimensionless form of the governing equations