UKC ANSAware Survival Guide (for Modula-3)

The ANSAware platform is a suite of libraries and tools which facilitate the building of distributed applications. The documentation with the release forms little more that a reference manual to the language and does not aid the first time user. This document provides a simple introduction to distributed systems concepts and, through the use of an example, demonstrates how to build applications with ANSAware

Fast Recompilation of Object Oriented Modules

Once a program file is modified, the recompilation time should be minimized, without sacrificing execution speed or high level object oriented features. The recompilation time is often a problem for the large graphical interactive distributed applications tackled by modern OO languages. A compilation server and fast code generator were developed and integrated with the SRC Modula-3 compiler and Linux ELF dynamic linker. The resulting compilation and recompilation speedups are impressive. The impact of different language features, processor speed, and application size are discussed

Identifikacija neispravnih spojeva u gredama uz pomoć torzijskih vibracija

The determination of the shear dynamic modulus in wood product panels is of greater importance than its determination in wood beams. Yet with regards to the effect of defects on the obtained values of shear modulus, this factor is used to detect the defects and the degree of the defects. In this study, the effect of gluing defects in two joint shapes (scarf (45°) and finger joints (10 mm length and 3 mm pitch) were evaluated non-destructively using the torsional vibration method. Rectangular wood specimens with dimensions of 20 mm × 40 mm × 360 mm (R × T × L) were prepared from clear eastern beech. The joints were located at similar positions in the middle of the beams. The results showed that creating a healthy joint did not significantly change the values obtained for the shear modulus in either of the joint shapes. However, reducing the adhesion level in both types of joints caused a significant reduction in the shear modulus values. The results show that the changes in the dynamic shear modulus values in both joint types, as a result of changes in the glue coverage rating (fully, medium and low-glued joints) allows the detection of the defects as well as the degree of the defects.Određivanje dinamičkog modula smicanja u drvnim pločama važnije je od određivanja tog modula u drvenim gredama. Ipak, s obzirom na utjecaj grešaka na vrijednosti modula smicanja, određivanje tog faktora važno je za otkrivanje grešaka i njihova stupnja na drvnim proizvodima. U ovom je istraživanju metodom torzijskih vibracija nedestruktivno procijenjen utjecaj grešaka lijepljenja u dva oblika spoja: kosim sljubom (45°) i klinastim zupcima (duljine 10 mm i koraka 3 mm). Uzorci drva dimenzija 20 mm × 40 mm × 360 mm (R × T × L) izrađeni su od čiste bukovine, a spojevi su izvedeni na približno istim mjestima na sredini greda. Rezultati su pokazali da izrada zdravog spoja nije bitno promijenila vrijednosti modula smicanja ni za jedan od primijenjenih tipova spoja. Međutim, smanjenje razine adhezije u obje vrste spojeva uzrokovalo je znatno smanjenje vrijednosti modula smicanja. Rezultati pokazuju da promjene vrijednosti dinamičkog modula smicanja u oba tipa spoja kao rezultat promjene stupnja pokrivenosti ljepilom (potpuna, srednja i slaba pokrivenost) omogućuju otkrivanje grešaka lijepljenja, kao i stupnja grešaka drvnih spojeva

Representations of certain irrational W-algebras

U disertaciji proučavamo neke iracionalne $\mathcal{W}$-algebre i njihove reprezentacije. Glavni primjer koji istražujemo je prosta Bershadsky-Polyakov verteks algebra $\mathcal{W}_k(=\mathcal{W}_k(sl_3, f_\theta))$, tj. minimalna afina $\mathcal{W}$-algebra pridružena $sl_3$. T. Arakawa je dokazao u članku [9] da je $\mathcal{W}_k$ racionalna ako je $k$ polucijeli broj veći od $-3/2$. Mi proučavamo slučajeve kad je $\mathcal{W}_k$ iracionalna, te klasificiramo $\mathcal{W}_k$-module za neke $k$. Klasifikacija ireducibilnih modula koristi Zhuovu teoriju i formule za singularne vektore. Istaknimo da je Zhuova algebra realizirana kao kvocijent Smithove algebre iz [44]. Klasifikacija ireducibilnih jakih modula za algebru $\mathcal{W}_k$ (tj. modula s konačno-dimenzionalnim težinskim potprostorima za operator $L(0)$) je zato povezana s klasifikacijom konačno-dimenzionalnih reprezentacija Smithove algebre. U slučaju $k=-5/3$ pokazujemo da je $\mathcal{W}_k$ realizirana kao verteks podalgebra Weylove verteks algebre. Dokazujemo da tada $\mathcal{W}_k$ ima točno 6 ireducibilnih jakih modula. U slučaju $k=-9/4$, $\mathcal{W}_k$ je važan primjer logaritamske verteks algebre. Klasificiramo jake $\mathcal{W}_k$ module za $k=-9/4$ i dokazujemo da $\mathcal{W}_k$ ima točno 3 ireducibilna jaka modula. Da bi pokazali da je $\mathcal{W}_k$ iracionalna, konstruiramo neprebrojivu familiju težinskih modula za $\mathcal{W}_k$ izvan kategorije $\mathcal{O}$. Konstruiramo familiju singularnih vektora koja generalizira Arakawine formule za singularne vektore za $k$ polucijeli broj iz [9]. U slučajevima $k=-1$ i $k=0$ klasificiramo sve module u kategoriji $\mathcal{O}$. U slučaju $k=0$, dajemo eksplicitnu realizaciju verteks algebre $\mathcal{W}_k$ i njenih modula kao određene iracionalne podalgebre verteks algebri pridruženih rešetkama. Također proučavamo algebru $\mathcal{W}_k$ u slučaju kad je $k$ cijeli broj veći od -1.In this thesis we study certain irrational $\mathcal{W}$-algebras and their representations. Main example that we investigate is the simple Bershadsky-Polyakov vertex algebra $\mathcal{W}_k(=\mathcal{W}_k(sl_3, f_\theta))$, i.e. the minimal affine $\mathcal{W}$-algebra associated to $sl_3$. T. Arakawa proved in [9] that $\mathcal{W}_k$ is rational if $k$ is a half integer greater that $-3/2$. We study cases where $\mathcal{W}_k$ is irrational, and classify $\mathcal{W}_k$-modules for certain $k$. Main tools that we use to classify irreducible modules are Zhu's theory and formulas for singular vectors. Zhu algebra is realized as a quotient of the Smith algebra from [44]. Classification of irreducible strong modules for $\mathcal{W}_k$ (i.e. modules with finite dimensional weight subspaces for the the operator $L(0)$) is hence connected to the classification of finite dimensional representations of the Smith algebra. In the case $k=-5/3$, we show that $\mathcal{W}_k$ is realized as a vertex subalgebra of the Weyl vertex algebra. We prove that in this case $\mathcal{W}_k$ has exactly 6 irreducible strong modules. In the case $k=-9/4$ , $\mathcal{W}_k$ is an important example of a logarithmic vertex algebra. We classify strong $\mathcal{W}_k$-modules for $k=-9/4$ and prove that $\mathcal{W}_k$ has exactly 3 irreducible strong modules. In order to show that $\mathcal{W}_k$ is irrational, we construct an uncountable family of weight modules for $\mathcal{W}_k$ outside of category $\mathcal{O}$. We construct a family of singular vectors which generalizes Arakawa’s formulas for singular vectors for $k$ half integer from [9]. For $k=-1$ and $k=0$ we classify all modules in the category $\mathcal{O}$. In the case $k=0$, we give an explicit realization of the vertex algebra $\mathcal{W}_k$ and its modules as certain irrational subalgebras of lattice VOAs. We also study the algebra $\mathcal{W}_k$ when $k$ is an integer greater than -1

A Novel Three-Point Modulation Technique for Fractional-N Frequency Synthesizer Applications

This paper presents a novel three-point modulation technique for fractional-N frequency synthesizer applications. Convention modulated fractional-N frequency synthesizers suffer from quantization noise, which degrades not only the phase noise performance but also the modulation quality. To solve this problem, this work proposes a three-point modulation technique, which not only cancels the quantization noise, but also markedly boosts the channel switching speed. Measurements reveal that the implemented 2.4 GHz fractional-N frequency synthesizer using three-point modulation can achieve a 2.5 Mbps GFSK data rate with an FSK error rate of only 1.4 %. The phase noise is approximately -98 dBc/Hz at a frequency offset of 100 kHz. The channel switching time is only 1.1 μs with a frequency step of 80 MHz. Comparing with conventional two-point modulation, the proposed three-point modulation greatly improves the FSK error rate, phase noise and channel switching time by about 10 %, 30 dB and 126 μs, respectively

Improving the performance of bright quantum dot single photon sources using amplitude modulation

Single epitaxially-grown semiconductor quantum dots have great potential as single photon sources for photonic quantum technologies, though in practice devices often exhibit non-ideal behavior. Here, we demonstrate that amplitude modulation can improve the performance of quantum-dot-based sources. Starting with a bright source consisting of a single quantum dot in a fiber-coupled microdisk cavity, we use synchronized amplitude modulation to temporally filter the emitted light. We observe that the single photon purity, temporal overlap between successive emission events, and indistinguishability can be greatly improved with this technique. As this method can be applied to any triggered single photon source, independent of geometry and after device fabrication, it is a flexible approach to improve the performance of solid-state systems, which often suffer from excess dephasing and multi-photon background emission

Hybrid M-FSK/DQPSK Modulations for CubeSat Picosatellites

Conventional CubeSat radio systems typically use one of several basic modulations, such as AFSK, GMSK, BPSK, QPSK and OOK or switch between them on demand if possible. These modulations represent a bal¬anced trade-off between good energy efficiency of high order M-FSK modulation and good spectral efficiency of high order M-QAM modulation. Utilization of modulations with the best energy efficiency is not possible due to strict limits on occupied frequency bandwidth. In this paper the proposed group of hybrid modulations and proposed hybrid modulator and demodulator are presented. Novel solution offer interesting possibilities of increasing spectral efficiency as well as energy efficiency of basic M-FSK modulation by embedding DQPSK symbols between two M-FSK symbols. Such group of hybrid modulations offers suitable properties for picosatellite, e.g. simple realization onboard the picosatellite, better energy and spectral efficiency, low PAPR, wide range of adaptation by changing the order of M-FSK, suitable for easy non-coherent demodulation, good immunity to Doppler effect with DM-FSK coding

Method and apparatus for quadriphase-shift-key and linear phase modulation

A submultiple of an S-band transmitter output frequency was divided equally between a linear phase modulation branch and a QPSK modulation branch. The linear modulation branch includes a multiplier to increase the carrier frequency to a level which, when combined with the carrier in the QPSK branch in an up-converter (utilizing a mixer at the input followed by a bandpass filter), produces the transmitter output frequency. This allows the QPSK modulator to operate at one-eighth of the output frequency where repeatable and precisely controlled modulation can be easily achieved. This also allows linear phase modulation at one-eighth the output frequency where low modulator deviation and good linearity can be easily maintained