Digital implementation of ETSI OFDM symbol synchronizer based on sliding correlation

This thesis presents the design, implementation, verification and synthesis of a digital hardware, which performs OFDM symbol synchronization using short training symbols (STS) defined in European Telecommunications Standards Institute (ETSI) HiperLan/2 Physical Layer specifications. Designed ETSI OFDM Symbol Synchronizer IP was synthesized in CMOS 0.13mM technology using Virtual Silicon Technology (VST) Standard Cell Libraries. In this thesis, we first explain OFDM and OFDM systems in detail. Synchronization problems occurring in OFDM systems are classified and techniques used to overcome these problems are presented. Then a digital ETSI OFDM Symbol Synchronizer IP, which performs OFDM symbol synchronization task based on the correlation of the received symbols, is proposed. Proposed architecture has been designed using VHDL (VHSIC Hardware Description Language) in the implementation part of the thesis. Designed IP has been verified functionally first, then synthesized in CMOS 0.13mM technology. Gate-level verification has been also performed after synthesis of the IP. Like other communication systems, synchronization is a critical problem to be solved in OFDM systems. One of the arguments against OFDM is that it is highly sensitive to synchronization errors. Before an OFDM receiver can demodulate the subcarriers, it has to perform at least two synchronization tasks: First, it has to find out where the symbol boundaries are. Second, it has to estimate and correct the carrier frequency offset of the received signal and clock offset between transmitter and receiver because any offset introduces Inter-carrier interference (ICI) and Inter-symbol interference (ISI). This work aims to review OFDM and synchronization issues in OFDM systems and to design a digital symbol synchronizer hardware that performs the detection of OFDM symbols, which is the first synchronization task mentioned above. ETSI HiperLAN/2 standard has been used in this work as the reference for all parameters needed and used in the hardware implementation of ETSI OFDM Symbol Synchronizer. Although the needed sampling frequency of OFDM receiver is 20 MHz in the ETSI standards, the designed IP can be run up to 50 MHz. It can be easily adapted to any changes in the standard, such as the increase in speed. The generically designed ETSI OFDM STS Symbol Synchronizer IP can be integrated to other modules easily and used as part of the whole synchronizer block in ETSI OFDM receivers

Life prediction and constitutive models for engine hot section anisotropic materials program

This report presents a summary of results from a 7 year program designed to develop generic constitutive and life prediction approaches and models for nickel-based single crystal gas turbine airfoils. The program was composed of a base program and an optional program. The base program addressed the high temperature coated single crystal regime above the airfoil root platform. The optional program investigated the low temperature uncoated single crystal regime below the airfoil root platform including the notched conditions of the airfoil attachment. Both base and option programs involved experimental and analytical efforts. Results from uniaxial constitutive and fatigue life experiments of coated and uncoated PWA 1480 single crystal material formed the basis for the analytical modeling effort. Four single crystal primary orientations were used in the experiments: group of zone axes (001), group of zone axes (011), group of zone axes (111), and group of zone axes (213). Specific secondary orientations were also selected for the notched experiments in the optional program. Constitutive models for an overlay coating and PWA 1480 single crystal materials were developed based on isothermal hysteresis loop data and verified using thermomechanical (TMF) hysteresis loop data. A fatigue life approach and life models were developed for TMF crack initiation of coated PWA 1480. A life model was developed for smooth and notched fatigue in the option program. Finally, computer software incorporating the overlay coating and PWA 1480 constitutive and life models was developed

Probabilistic Structural Analysis Methods for select space propulsion system components (PSAM). Volume 2: Literature surveys of critical Space Shuttle main engine components

The technical effort and computer code development is summarized. Several formulations for Probabilistic Finite Element Analysis (PFEA) are described with emphasis on the selected formulation. The strategies being implemented in the first-version computer code to perform linear, elastic PFEA is described. The results of a series of select Space Shuttle Main Engine (SSME) component surveys are presented. These results identify the critical components and provide the information necessary for probabilistic structural analysis. Volume 2 is a summary of critical SSME components

Structural properties of laminated Douglas fir/epoxy composite material

This publication contains a compilation of static and fatigue strength data for laminated-wood material made from Douglas fir and epoxy. Results of tests conducted by several organizations are correlated to provide insight into the effects of variables such as moisture, size, lamina-to-lamina joint design, wood veneer grade, and the ratio of cyclic stress to steady stress during fatigue testing. These test data were originally obtained during development of wood rotor blades for large-scale wind turbines of the horizontal-axis (propeller) configuration. Most of the strength property data in this compilation are not found in the published literature. Test sections ranged from round cylinders 2.25 in. in diameter to rectangular slabs 6 by 24 in. in cross section and approximately 30 ft. long. All specimens were made from Douglas fir veneers 0.10 in. thick, bonded together with the WEST epoxy system developed for fabrication and repair of wood boats. Loading was usually parallel to the grain. Size effects (reduction in strength with increase in test volume) are observed in some of the test data, and a simple mathematical model is presented that includes the probability of failure. General characteristics of the wood/epoxy laminate are discussed, including features that make it useful for a wide variety of applications

Space programs summary number 37-29, volume iv for the period august 1, 1964 to september 30, 1964. supporting research and advanced development

Systems, guidance and control, engineering mechanics and facilities, propulsion, space sciences, and telecommunications researc

User's manual for the NASA Lewis ice accretion/heat transfer prediction code with electrothermal deicer input

A version of LEWICE has been developed that incorporates a recently developed electrothermal deicer code, developed at the University of Toledo by William B. Wright. This was accomplished, in essence, by replacing a subroutine in LEWICE, called EBAL, which balanced the energies at the ice surface, with a subroutine called UTICE. UTICE performs this same energy balance, as well as handles all the time-timperature transients below the ice surface, for all of the layers of a composite blade as well as the ice layer itself. This new addition is set up in such a fashion that a user may specify any number of heaters, any heater chordwise length, and any heater gap desired. The heaters may be fired in unison, or they may be cycled with periods independent of each other. The heater intensity may also be varied. In addition, the user may specify any number of layers and thicknesses depthwise into the blade. Thus, the new addition has maximum flexibility in modeling virtually any electrothermal deicer installed into any airfoil. It should be noted that the model simulates both shedding and runback. With the runback capability, it can simulate the anti-icing mode of heater performance, as well as detect icing downstream of the heaters due to runback in unprotected portions of the airfoil. This version of LEWICE can be run in three modes. In mode 1, no conduction heat transfer is modeled (which would be equivalent to the original version of LEWICE). In mode 2, all heat transfer is considered due to conduction but no heaters are firing. In mode 3, conduction heat transfer where the heaters are engaged is modeled, with subsequent ice shedding. When run in the first mode, there is virtually identical agreement with the original version of LEWICE in the prediction of accreted ice shapes. The code may be run in the second mode to determine the effects of conduction on the ice accretion process