Synthesegerechte Konvertierung synchroner in asynchrone Schaltungen für FPGAs

Asynchrone Schaltungen haben Vorteile im Bereich der EMV und des Energieverbrauchs. Die vorliegende Arbeit beschreibt einen Ansatz, synchrone in asynchrone Schaltungen zu konvertieren und für einen FPGA zu synthetisieren. Es wird gezeigt wie spezielle Bauelemente für asynchrone Schaltungen auf FPGAs realisiert werden können, dabei wird insbesondere auch die Möglichkeit diskutiert, die üblichen Delay Chains durch „Delay Shift“-Elemente zu ersetzen. Anschließend wird ein Konvertierungsablauf für VHDL beschrieben und ein Beispiel vorgestellt. Im Ergebnis wird die Funktionsfähigkeit des vorgestellten Konvertierungsansatzes demonstriert; es zeigt sich dabei, dass die Performanceerwartungen nur bedingt erfüllt werden. Sämtliche Software die verwendet wurde ist frei verfügbar.Asynchronous circuits have advantages in the Field of EMC and energy consumption. The present thesis describes how to convert a synchronous into an asynchronous circuit and how to synthesize it for an FPGA. It is shown how specific components for asynchronous circuits can be realized on FPGAs; in the process, it is specifically discussed to replace the usual Delay Chains by “Delay Shift” components. The conversion sequence is described for VHDL and an example is presented. It is demonstrated that the conversion approach is operational, but that prior performance expectations are only partly fulfiled. All the software used is free

Analysis of the polarization distribution in a polar perhydrotriphenylene inclusion compound by scanning pyroelectric microscopy

The polarization distribution in a polar perhydrotriphenylene (PHTP) inclusion compound has been studied by scanning pyroelectric microscopy. Measurements have been performed on solution-grown crystals of PHTP-AD (AD: acceptor(A) and donor (D) disubstituted linear chromophores). The AD guest molecules form aligned dipole chains within the parallel channels created by the honeycomb-type host lattice of PHTP. Along the channel direction we found a 180 degrees twinned macrodomain state with wedge-shaped domain boundaries adjacent to the middle of the needle-shaped crystals. In each domain the polarization is nearly constant, which implies that the majority of molecular dipoles are aligned parallel. This agrees well with predictions arising from the application of Markov's theory of stochastic processes, which explains the occurrence of polar domains due to a mechanism of dipole incorporation driven by the difference in the -A...A- and -D...D- intermolecular interaction energies.status: publishe

Analysis of complex dielectric spectra. II. Evaluation of the activation energy landscape by differential sampling

Relaxation phenomena are controlled by thermally activated or by free-volume activated kinetics. Evaluation of the kinetic parameters across the whole experimental window is of prime importance. Techniques that provide information about the entire landscape of activation energies or fractional free volumes are discussed. Emphasis is given to a fine-structure analysis by bivariate differential sampling and its potential for studying the glass transition dynamics in equilibrium and non-equilibrium (physical aging) is shown. (C) 2002 Published by Elsevier Science B.V.status: publishe

Analysis of complex dielectric spectra. I. One-dimensional derivative techniques and three-dimensional modelling

Several strategies for the analysis of isochronal and isothermal spectra as well as complete three-dimensional (313) spectra are outlined and applied to data of (glass forming) liquids and polymers. Conduction-free loss spectra are calculated using a compact solution of the Kramers-Kronig transformation and an approximation based on partial derivativeepsilon'/partial derivative In omega. The usefulness of the dielectric modulus for data analysis is also evaluated. Apart from partial derivativeepsilon'/partial derivative In omega. other useful derivatives in the frequency and temperature domain are treated as well. Finally, we describe the evaluation of 3D-relaxation maps by means of 3D fitting. (C) 2002 Elsevier Science B.V. All rights reserved.status: publishe

Pyroelectric effects on molecular-sieve crystals loaded with dipole molecules

The pyroelectric effects of dipolar guest molecules in molecular sieve crystals have been studied for the first time. The measurements have been done on assemblages of aligned crystals as well as on individual single crystals of the aluminophosphate molecular sieve AlPO4-5 loaded with p-nitroaniline (PNA). The PNA molecules form unidirectionally aligned dipole chains in parallel molecular sieve channels. We found that the PNA dipoles are oppositely directed in the two halves of a single crystal, forming two macroscopic regions of opposite polarization. It is concluded that the preferred direction of the dipole chains in the channel is a result of the adsorption process of the molecules into the channels.status: publishe