Tree-ring analyses of European oak: implementation and relevance in (pre-)historical research in Flanders.

Throughout human history, forests and woodlands in Western Europe experienced a high anthropogenic influence. In densely populated areas forests were cleared and converted to arable land or were exploited for the supply of firewood and construction timber. In Flanders, it is estimated that the forest cover by the end of the 13th century was even lower than in the 19th century. To date, several assortments of timber, available on the local wood market during the Roman era and the Middle Ages, have become part of our cultural heritage. Archaeological remains, historical buildings, panel paintings and religious sculptures are only a few examples of constructions and objects that were created by processing wood. Especially European oak (Quercus robur L. and Q. petraea (Matt.) Liebl.) was highly esteemed by craftsmen. Tree-ring series of oak have the characteristic that they tend to crossdate. In other words, ring-width series display a certain element of synchronicity between remote sites. This feature allows to use dendrochronology, i.e. the scientific study of tree-ring patterns, as a dating tool. However, in Flanders tree-ring dating has seldom been applied and has often led to inconclusive results. Especially archaeological oak timbers or wood from historical buildings is often characterized by short (less than 50 years) and variable growth patterns. Therefore, it was assessed and demonstrated that such series have a potential for dating purposes and chronology building. It is believed that the high anthropogenic pressure on the original forest cover has stimulated the implementation of short rotation systems. Past forest management interventions and forest stand structure development are recorded in the growth patterns and the wood anatomical structure of archaeological and subfossil wood. By comparing them with growth patterns of contemporary trees from stands with well-known stand structure and management history it was noticed that the same patterns are encountered. Consequently, it is now possible to distinguish wood specimens that originate from, for instance, a coppice stand or a high forest by scrutinizing their growth patterns. Moreover, close observation of the wood anatomy, for instance, the size and distribution of earlywood vessels, provides an image of the variability in past hydrological conditions. Tree-ring series from wooden sculptures and panel paintings from 15th-16th century display a completely different nature. Since local timber sources mostly provided small sized and fast grown timber, craftsmen started to look for high-quality oak. Such assortments became available due to the establishment of an important timber trade. Especially oak timber from the Baltic region was imported. By studying the growth patterns on historical art objects it becomes clear that medieval woodworkers were well aware of the intrinsic variability and technological properties of the imported oak timber. Moreover, analysis of extensive datasets of tree-ring series from historical art objects provides more insights and information on the original timber source, wood processing activities and the creative process. It is obvious that dendrochronology has become more than a dating tool in (pre-) historical studies. This work demonstrates that it is highly valid to approach Flanders’ precious cultural heritage, created out of wood, from a multidisciplinary point-of-view, where archaeology, art-history, wood technology and biology should play an important and valuable role

Tree-ring analyses of European oak: implementation and relevance in (pre-)historical research in Flanders

Throughout human history, forests and woodlands in Western Europe experienced a high anthropogenic influence. In densely populated areas forests were cleared and converted to arable land or were exploited for the supply of firewood and construction timber. In Flanders, it is estimated that the forest cover by the end of the 13th century was even lower than in the 19th century. To date, several assortments of timber, available on the local wood market during the Roman era and the Middle Ages, have become part of our cultural heritage. Archaeological remains, historical buildings, panel paintings and religious sculptures are only a few examples of constructions and objects that were created by processing wood. Especially European oak (Quercus robur L. and Q. petraea (Matt.) Liebl.) was highly esteemed by craftsmen. Tree-ring series of oak have the characteristic that they tend to crossdate. In other words, ring-width series display a certain element of synchronicity between remote sites. This feature allows to use dendrochronology, i.e. the scientific study of tree-ring patterns, as a dating tool. However, in Flanders tree-ring dating has seldom been applied and has often led to inconclusive results. Especially archaeological oak timbers or wood from historical buildings is often characterized by short (less than 50 years) and variable growth patterns. Therefore, it was assessed and demonstrated that such series have a potential for dating purposes and chronology building. It is believed that the high anthropogenic pressure on the original forest cover has stimulated the implementation of short rotation systems. Past forest management interventions and forest stand structure development are recorded in the growth patterns and the wood anatomical structure of archaeological and subfossil wood. By comparing them with growth patterns of contemporary trees from stands with well-known stand structure and management history it was noticed that the same patterns are encountered. Consequently, it is now possible to distinguish wood specimens that originate from, for instance, a coppice stand or a high forest by scrutinizing their growth patterns. Moreover, close observation of the wood anatomy, for instance, the size and distribution of earlywood vessels, provides an image of the variability in past hydrological conditions. Tree-ring series from wooden sculptures and panel paintings from 15th-16th century display a completely different nature. Since local timber sources mostly provided small sized and fast grown timber, craftsmen started to look for high-quality oak. Such assortments became available due to the establishment of an important timber trade. Especially oak timber from the Baltic region was imported. By studying the growth patterns on historical art objects it becomes clear that medieval woodworkers were well aware of the intrinsic variability and technological properties of the imported oak timber. Moreover, analysis of extensive datasets of tree-ring series from historical art objects provides more insights and information on the original timber source, wood processing activities and the creative process. It is obvious that dendrochronology has become more than a dating tool in (pre-) historical studies. This work demonstrates that it is highly valid to approach Flanders’ precious cultural heritage, created out of wood, from a multidisciplinary point-of-view, where archaeology, art-history, wood technology and biology should play an important and valuable role

On the Boundedness Problem for Higher-Order Pushdown Vector Addition Systems

International audienceKarp and Miller's algorithm is a well-known decision procedure that solves the termination and boundedness problems for vector addition systems with states (VASS), or equivalently Petri nets. This procedure was later extended to a general class of models, well-structured transition systems, and, more recently, to pushdown VASS. In this paper, we extend pushdown VASS to higher-order pushdown VASS (called HOPVASS), and we investigate whether an approach à la Karp and Miller can still be used to solve termination and boundedness.We provide a decidable characterisation of runs that can be iterated arbitrarily many times, which is the main ingredient of Karp and Miller's approach. However, the resulting Karp and Miller procedure only gives a semi-algorithm for HOPVASS. In fact, we show that coverability, termination and boundedness are all undecidable for HOPVASS, even in the restricted subcase of one counter and an order 2 stack. On the bright side, we prove that this semi-algorithm is in fact an algorithm for higher-order pushdown automata

7th EEEIC International Workshop on Environment and Electrical Engineering : Wroclaw - Cottbus, 5 - 11. May 2008

The proposed solution meets the latest trends in world power engineering and has the lowest ecological costs amongst the accessible power engineering solutions. It is also in accordance with the Polish power engineering law, which takes into account the recommendations of the European Economic Commission, the Second Sulphur Protocol and the Framework Convention of the United Nations (concerning the changes of climate)

Upowszechnianie wyników badań naukowych w międzynarodowych bazach danych : analiza biometryczna na przykładzie nauk technicznych, ze szczególnym uwzględnieniem elektrotechniki

The issues of bibliometrics, scientometrics, informetrics and webometrics have an important place among research subject undertaken by Polish and foreign scholars. Initially, these notions were used only by researchers in the fields of library science, scientometrics and information science. However, at the turn of the 20th and 21st centuries, quantitative methods became a fundamental tool for evaluation of, among others, sources of academic communication, academic research, research and academic centers. One of the elements of the evaluation is a quantitative analysis of academic publications in databases with international access. It is of particular importance in the case of technical sciences. This work is an attempt at a quantitative analysis of publications by Polish authors (affiliated to Polish technical universities) and Polish journals on electrotechnics in international databases. The contents are organized into four chapters with an introduction, conclusions, bibliography, name index and a list of figures and illustrations. Chapters one and two are devoted to theoretical issues, whereas chapters three and four – to practical issues. In the first chapter, selected issues concerning quantitative methods were presented, including an analysis of literature and a discussion over terminology carried out in book publications and journals. Moreover, selected examples of research conducted with the use of quantitative methods (including rankings and scientific reports) were discussed in this chapter). In chapter two, sources of information on academic publications, their origins and development (from bibliographic bases to citation indexes) were presented. A separate subchapter was devoted to databases of academic publications created by libraries of technical universities, and to indicators in the assessment of academic publications. Chapter three deals with electrotechnics as a field of science. An analysis was conducted with regard to the place of electrotechnics in science classifications based on selected examples, and the development of the teaching of electrotechnics at university level was shown. In this chapter, early and contemporary Polish journals on electrotechnics were presented, including journals published by technical universities themselves. Chapter four contains the results of an analysis of international databases (Scopus, WoS, CC), focusing on the representation of Polish journals, including their citations, and publications of authors with affiliation to Polish technical universities. Final conclusions of research and analyses have brought an answer to questions raised with regard to the assessment of representation in international databases of publications by Polish authors affiliated to Polish technical universities (in its various aspects, e.g., a publication type, language of publication, publication dynamics taking into account years of publications, cooperation with representatives of other European and non-European countries), and of Polish journals

Advances in Fluid Power Systems

The main purpose of this Special Issue of “Advances in Fluid Power Systems” was to present new scientific work in the field of fluid power systems for hydraulic and pneumatic control of machines and devices used in various industries. Advances in fluid power systems are leading to the creation of new smart devices that can replace tried-and-true solutions from the past. The development work of authors from various research centres has been published. This Special Issue focuses on recent advances and smart solutions for fluid power systems in a wide range of topics, including: • Fluid power for IoT and Industry 4.0: smart fluid power technology, wireless 5G connectivity in fluid power, smart components, and sensors.• Fluid power in the renewable energy sector: hydraulic drivetrains for wind power and for wave and marine current power, and hydraulic systems for solar power. • Hybrid fluid power: hybrid transmissions, energy recovery and accumulation, and energy efficiency of hybrid drives.• Industrial and mobile fluid power: industrial fluid power solutions, mobile fluid power solutions, eand nergy efficiency solutions for fluid power systems.• Environmental aspects of fluid power: hydraulic water control technology, noise and vibration of fluid power components, safety, reliability, fault analysis, and diagnosis of fluid power systems.• Fluid power and mechatronic systems: servo-drive control systems, fluid power drives in manipulators and robots, and fluid power in autonomous solutions

Axiomatizing Prefix Iteration with Silent Steps

Prefix iteration is a variation on the original binary version of the Kleene star operation P*Q, obtained by restricting the first argument to be an atomic action. The interaction of prefix iteration with silent steps is studied in the setting of Milner's basic CCS. Complete equational axiomatizations are given for four notions of behavioural congruence over basic CCS with prefix iteration, viz. branching congruence, eta-congruence, delay congruence and weak congruence. The completeness proofs for eta-, delay, and weak congruence are obtained by reduction to the completeness theorem for branching congruence. It is also argued that the use of the completeness result for branching congruence in obtaining the completeness result for weak congruence leads to a considerable simplification with respect to the only direct proof presented in the literature. The preliminaries and the completeness proofs focus on open terms, i.e. terms that may contain process variables. As a by-product, the omega-completeness of the axiomatizations is obtained as well as their completeness for closed terms. AMS Subject Classification (1991): 68Q10, 68Q40, 68Q55.CR Subject Classification (1991): D.3.1, F.1.2, F.3.2.Keywords and Phrases: Concurrency, process algebra, basic CCS, prefix iteration, branching bisimulation, eta-bisimulation, delay bisimulation, weak bisimulation, equational logic, complete axiomatizations

Seasonal and spatial variability of major organic contaminants in solution and suspension of the Pomeranian Bight

Studies of hexachlorocyclohexane-isomers (HCHs) and selected triazine herbicides in solution and suspension were carried out in the Pomeranian Bight in 1995. The concentrations of HCHs and triazines were determined by gas-liquid chromatography (GC) or by GC in connection with quadrupole mass spectrometry(GC/MS). Particulate and dissolved material were separated by means of an in-situ filtration/extraction system. The seasonal variability and regional distribution of the various components were investigated in January, April, July and September 1995. Their distribution in the western Pomeranian Bight is described. The concentrations of individual hexachlorocyclohexane-isomers were in the range of 100–1 000 pg l–1 in solution and 20 to 60 pg l–1 in suspension. The levels of the triazines in solution showed pronounced differences between the individual components (atrazine (2–20 ng l–1), simazine (5–30 ng l–1), terbuthylazine (< 5 ng l–1)), but they were one order of magnitude higher compared with the hexachlorocyclohexane-isomers. The concentration of triazines in suspension was low, often below the limit of detection (25 pg l–1)

Aeronautical engineering: A continuing bibliography, supplement 122

This bibliography lists 303 reports, articles, and other documents introduced into the NASA scientific and technical information system in April 1980