An Hinf based robust altitude hold flight control system for a tactical UAV

In this paper altitude hold control system based on robust Hinf controller is considered. Tactical UAV is used as a platform for design. Simulations, which illustrate performance of the altitude control system are performed for various atmospheric disturbances, including turbulence and wind gusts

Impact of mid-successional dominant species on the diversity and progress of succession in regenerating temperate grasslands

(i) Which species dominate mid-successional old-fields in Hungary? How does the identity of these species relate to local (patch-scale) diversity and to the progress of succession? (ii) Which species have the strongest negative impact on diversity in spontaneous old-field succession and what generalizations are possible about traits of these species? (iii) Are these species dominant or subordinate components in mature target communities? (iv) Do native or alien species have stronger effects on the diversity and progress of succession

1-Lipschitz Neural Networks are more expressive with N-Activations

A crucial property for achieving secure, trustworthy and interpretable deep learning systems is their robustness: small changes to a system's inputs should not result in large changes to its outputs. Mathematically, this means one strives for networks with a small Lipschitz constant. Several recent works have focused on how to construct such Lipschitz networks, typically by imposing constraints on the weight matrices. In this work, we study an orthogonal aspect, namely the role of the activation function. We show that commonly used activation functions, such as MaxMin, as well as all piece-wise linear ones with two segments unnecessarily restrict the class of representable functions, even in the simplest one-dimensional setting. We furthermore introduce the new N-activation function that is provably more expressive than currently popular activation functions. We provide code at https://github.com/berndprach/NActivation

Almost-Orthogonal Layers for Efficient General-Purpose Lipschitz Networks

It is a highly desirable property for deep networks to be robust against small input changes. One popular way to achieve this property is by designing networks with a small Lipschitz constant. In this work, we propose a new technique for constructing such Lipschitz networks that has a number of desirable properties: it can be applied to any linear network layer (fully-connected or convolutional), it provides formal guarantees on the Lipschitz constant, it is easy to implement and efficient to run, and it can be combined with any training objective and optimization method. In fact, our technique is the first one in the literature that achieves all of these properties simultaneously. Our main contribution is a rescaling-based weight matrix parametrization that guarantees each network layer to have a Lipschitz constant of at most 1 and results in the learned weight matrices to be close to orthogonal. Hence we call such layers almost-orthogonal Lipschitz (AOL). Experiments and ablation studies in the context of image classification with certified robust accuracy confirm that AOL layers achieve results that are on par with most existing methods. Yet, they are simpler to implement and more broadly applicable, because they do not require computationally expensive matrix orthogonalization or inversion steps as part of the network architecture. We provide code at https://github.com/berndprach/AOL.Comment: - Corrected the results from competitor ECO. - Corrected a typo in the loss function equatio

EFFECTS OF CHEMICAL COMPOSITION ON MECHANICAL PROPERTIES OF Al-Mg-Si-Mn BASED ALLOYS

Effects of chemical composition and heat treatment on the microstructural and mechanical properties of cast Al-Mg-Si-Mn alloys were investigated. The as-cast and heat treated alloys were investigated by microhardness, macrohardness and tensile stress measurements, scanning and transmission electron microscopy, energy dispersive X-ray analysis and differential scanning calorimetry. It was observed that the mechanical properties depend strongly on composition and addition of excess elements and eutectic phase. Heat treatment leads to the enhancement of all mechanical properties of alloys, which are the result of several mechanisms

ULTRASONIC SOLDERING OF Cu AND Al2O3 CERAMICS BY USE OF Bi-La AND Bi-Ag-La SOLDERS

This work deals with the effect of solder alloying with a small amount of lanthanum on joint formation with metallic and ceramic substrate. The Bi-Ag – based solder with 2 wt.% lanthanum addition and Bi solder with 2 wt.% lanthanum addition were studied. Soldering was performed by afluxless process on the air, by activation with a power ultrasound. It was found out that, during the process of ultrasonic soldering, lanthanum is distributed on the boundary, both with the copper and the ceramic substrate, which enhances the joint formation. The bond with Al2O3 ceramics is of an adhesive character, without the formation of a new contact interlayer

Боковой автопилот для тактического БпЛА

Розроблено систему керування для бокового автопілоту тактичного безпілотного літального апарату (TБПЛА), який стежить за командами, що генеровані системою наведення, та стабілізує об’єкт керування. З метою порівняння використано два різні алгоритми: ПІД регулятор та методика синтезу H∞ Моделювання в MATLAB/Simulink показує, що якість роботи систем керування для обох алгоритмів відповідає вказаним вимогам як для номінальної моделі, так і для моделі з урахуванням неточностей в задані динаміки літака, а також в присутності шумів датчиків, проте H∞ регулятор ілюструє кращі шумоподавляючі властивості, ніж ПІД алгоритм.A control system for a lateral autopilot of a tactical unmanned aerial vehicle (TUAV), which follows the commands generated by the guidance system, and stabilizes the vehicle, is designed. Two different algorithms are used in comparison purposes: PID controller and H∞ design technique. Simulation in MATLAB/Simulink shows that performances of the control systems for both algorithms satisfy the specified requirements for the nominal model, as well as for the model with uncertainties on airplane’s dynamics, and with a sensor noise presence, however, H∞ controller illustrates better noise rejection properties than PID algorithm.Разработана система управления для бокового автопилота тактического беспилотного летательного аппарата (TБПЛА), который отслеживает команды, генерированные системой наведения, и стабилизирует объект управления. С целью сравнения использовано два различных алгоритма: ПІД регулятор и методику синтеза H∞ Моделирование в MATLAB/Simulink показывает, что качество работы систем управления для обоих алгоритмов отвечает указанным требованиям как для номинальной модели, так и для модели с учетом неточностей в заданнии динамики самолета, а также в присутствии щумов датчиков, однако H∞ регулятор іллюстрирует лучшие шумоподавляющие свойства, чем ПІД алгоритм

Breeding Distribution and Numbers of Black Guillemots in Jones Sound, N.W.T.

Aerial surveys of Jones Sound, N.W.T., reveal a highly clumped distribution of black guillemots in the early spring and throughout the breeding season. Black guillemots are uncommon throughout much of Jones Sound except at its mouth and in the western portion. By September most guillemots have left the area. Both early spring and breeding distributions appear to be influenced by the Hell Gate and Cardigan Strait polynya located in western Jones Sound between Ellesmere and Devon islands. Evidence presented suggests that annual variation in the distribution of ice edges in Jones Sound may influence distribution of breeding birds among suitable breeding sites.Key words: black guillemot, Cepphus grylle, breeding distribution, Jones Sound, aerial surveysRÉSUMÉ. Des relevés aériens effectués dans le détroit de Jones (T.N.-0.) indiquent une distribution trés regroupée de guillemots à miroir au début du printemps et durant toute la saison de reproduction. On ne trouve pas beaucoup de guillemots à miroir dans l’ensemble du détroit de Jones, sauf à son embouchure et dans la partie occidentale. Quand arrive septembre, la plupart des guillemots ont quitté la région. Les distributions du début du printemps et de la saison de reproduction semblent être influencées par les polynias de Hell Gate et de Cardigan Strait situées dans la partie occidentale du détroit de Jones, entre les îles Devon et Ellesmere. Les faits présentés suggèrent que la variation annuelle dans la distribution des lisières de glaces du détroit de Jones pourrait influencer la distribution des oiseaux reproducteurs aux divers sites qui se prêtent à la nidificationMots clés: guillemot à miroir, Cepphus grylle, distribution de la nidification, détroit de Jones, relevés aérien

Anthracological perspective on vegetation history in Roztoky u Prahy

Tato práce se zabývá výzkumem vývoje lesa a jeho ovlivnění lidským osídlením během pravěku a raného středověku metodou analýzy půdních uhlíků neboli pedoantrakologie. Zabývá se lokalitou v historicky jednom z nejdéle osídlených území České republiky, Roztockým hájem u Roztok u Prahy ve středních Čechách. Pedoantrakologie poskytuje velmi lokální a lidským jednáním relativně málo ovlivněnou informaci o historické dřevinné vegetaci. Naproti tomu archeoantrakologie zkoumá uhlíky pocházející z archeologických výzkumů přímo z míst lidského osídlení. Jejich vznik je výrazně ovlivněn lidským jednáním a poskytují syntetický obraz o vegetaci širšího okolí zkoumané lokality. Porovnání výsledků těchto dvou přístupů je v případě Roztok možné díky dlouhodobému archeologickému výzkumu, ze kterého pochází již dříve analyzovaný a částečně publikovaný soubor uhlíků. Nově získaný pedoantrakologický soubor přináší detailnější prostorové měřítko, možnost zjištění vlivu lokálních podmínek a vzdálenosti od osídlení na historická druhová spektra, nebo možnost identifikace v archeoantrakologickém souboru nadhodnocených selektivně vybíraných druhů. Další částí práce je popis současné vegetace v okolí půdních sond a zjištění její případné návaznosti na historická uhlíková spektra. 4 půdní sondy poskytly uhlíkový soubor,...This thesis researches forest history and human impact on it in prehistory and early Middle Ages by means of soil charcoal analysis, i.e. pedoanthracology. It focuses on a site called "Roztocký háj" with long-term human settlement near Roztoky u Prahy in central Bohemia. Pedoanthracology brings information about past woody vegetation that is very local and without much anthropogenic influence. On the other hand, archeoanthracology focuses on charcoal originating from archeological excavations directly from human settlements. These charcoals are therefore formed by human behaviour and provide general view on woody vegetation in wider surroundings of the site. Comparing results of these two approaches in Roztoky is allowed by long-term archeological excavations. They provided previously analyzed and partially published charcoal dataset. Newly obtained pedoanthracological dataset brings finer spatial scale, allows to find out the effect of local conditions on the charcoal spectra and also allows identification of possible purposefully selected taxa in the archeoanthracological assemblage. Another part of this work describes present-day vegetation around the soil profiles and examines it's possible continuity with the past vegetation. 4 soil profiles provided quite species-rich (17 taxa) charcoal...Department of BotanyKatedra botanikyPřírodovědecká fakultaFaculty of Scienc