Topology Control with Anisotropic and Sector Turning Antennas in Ad-hoc and Sensor Networks

During the last several years, technological advances have allowed the development of small, cheap, embedded, independent and rather powerful radio devices that can self-organise into data networks. Such networks are usually called ad-hoc networks or, sometimes, depending on the application field, sensor networks. One of the first standards for ad-hoc networks to impose itself as a fully industrial framework for data gathering and control over such devices is IEEE 802.15.4 and, on top of it, its pair network architecture: ZigBee. In the case of multiple radio devices clamped into a small geographical area, the lack of radio bandwidth becomes a major problem, leading to multiple data losses and unnecessary power drain from the batteries of these small devices. This problem is usually perceived as interference. The deployment of appropriate topology control mechanisms (TC) can solve interference. All of these algorithms calculate TC on the basis of isotropic antenna radiation patterns in the horizontal plane

Influencia de las bajas temperaturas y la duración de las heladas en la viabilidad de Phytophthora alni subsp. Alni

Limits on the survival of P. alni subsp. alni (PAA) due to low temperature can be expected based on previously published laboratory and field studies. This study presents a laboratory experiment to test the influence of low temperature and frost duration on PAA viability. Ten PAA isolates were incubated at different temperatures (–0.1, –2.5, –5.0, –7.5, and –10.0 °C) and frost durations (0 – 7, 14, 21, and 28 days). A regression analysis confirmed the significant influence of both factors (low temperature and frost duration, and their interaction) on the survival of the pathogen under laboratory conditions. The survival and failure time analysis showed that the survival of the pathogen differs significantly after mild frost (all the isolates tested survived temperatures between –0.1 and –5.0 °C during the entire testing period) and heavy frost (the pathogen died after 21 days of incubation at –7.5 °C and after 2 days at –10.0 °C). Moreover, the viability of the pathogen decreased significantly if the temperature of –5.0 °C was maintained for at least 1 week and the temperature of –7.5 °C persisted in laboratory conditions for at least 4 days. The results of the study proved the pathogen to be very sensitive to heavy frost. The low-temperature limits for PAA occur regularly in Central Europe in January. It is probable that these temperatures can reduce PAA populations in diseased black alder stems. The climate change characterised by increases in the lowest minimum winter temperatures in Central Europe (as hypothesised by IPCC) may pose a significant risk for affected alder population in the area.Se pueden esperar límites a la supervivencia de P. alni subsp. alni (PAA), debido a las bajas temperaturas basándose en resultados obtenidos en laboratorio y estudios de campo. Este estudio presenta un experimento de laboratorio para probar la influencia de las bajas temperaturas y la duración de las heladas sobre la viabilidad de PAA. Se incubaron diez cepas PAA a diferentes temperaturas (–0,1, –2,5, –5,0, –7,5 y –10,0 °C) y duración de heladas (0 – 7, 14, 21, y 28 días). Un análisis de regresión confirmó la importante influencia de ambos factores (bajas temperaturas y la duración de heladas, así como su interacción) en la supervivencia del patógeno en las condiciones de laboratorio. La supervivencia y el análisis de tiempo de fallo demostró que la supervivencia del patógeno difiere significativamente después de las heladas suaves (todas las cepas aisladas sobrevivieron a temperaturas entre –0,1 y –5,0 °C durante el período completo de la prueba) y heladas fuertes (el patógeno murió tras 21 días de incubación a –7,5 °C y después de 2 días a –10,0 °C). Además, la viabilidad del patógeno disminuyó significativamente si la temperatura de –5,0 °C se mantenía durante al menos 1 semana, o la temperatura de –7,5 °C se mantenía durante al menos 4 días. Los resultados del estudio muestran que el patógeno es muy sensible a las heladas intensas. Los límites de baja temperatura para el PAA se producen regularmente en Europa Central en enero. Es probable que estas temperaturas puedan reducir las poblaciones de la PAA en los árboles enfermos de aliso negro. El cambio climático caracterizado por el aumento de las temperaturas mínimas más bajas del invierno en Europa Central (como hipotetiza el IPCC) puede suponer un riesgo significativo para la población afectada de alisos en este área

Obrada čelika P2-04BCH kutno kanalnom ekstruzijom (KKE)

The article presents results of investigation of structure and properties of low-carbon steel grade P2-04BCH after application of ECAE at temperature of approx. 290C. The ECAE method leads to significant improvement of strength of investigated material. Investigation of structure was made by combination of TEM and FEG SEM together with EBSD. It was proven the ECAE method enables obtaining of ultra fine-grained ferritic structure formed by recrystallised grains with very low density of dislocations and with a small portion of spheroidised carbides, which occurred usually on the boundaries of ferritic grains.Članak prikazuje rezultate istraživanja strukture i svojstava niskougljičnog čelika kvalitete P2-04BCH nakon kanalno kutne ekstruzije (KKE) pri temperaturi od oko 290°C. Zabilježen je značajan porast čvrstoće materijala. Struktura je ispitana kombinacijom transmisijskog elektronskog mikroskopa (TEM), skenirajućeg elektronskog mikroskopa s emisijom polja (FEG SEM) te elektronskom difrakcijom (EBSD). Dokazano je da se jednakokanalnom kutnom ekstruzijom postiže izuzetno sitnozrnata feritna struktura rekristalizacijom zrna, uz vrlo nisku gustoću dislokacija i mali udio sferičnih karbida s rasporedom, obično na granicama feritnih zrna

QUALITY OF SUGAR BEET ROOT IN RELATION TO WEATHER CONDITIONS AND DIFFERENT ATONIK DOSES

V poľných polyfaktorových pokusoch uskutočnených v rokoch 1998 a 1999 na stredne ťažkej černozemi bol sledovaný vplyv poveternostných podmienok ročníka a rôznych dávok Atoniku na výťažnosť rafinády a úrodu rafinády cukrovej repy odrody Ranger. Priaznivejší priebeh zrážok a teplôt roku 1999 potvrdil štatisticky vysoko preukazný vplyv pestovateľského ročníka, ktorý sa prejavil v porovnaní s priemerom pokusného obdobia v hodnotách zvýšenia nielen výťažnosti rafinády (+ 0,67 % ,rel. 5,53 %) ale i úrody rafinády (+ 0,67 t.ha-1, rel. 9, 75 %). V daných pôdnoklimatických podmienkach sme dosiahli vyššie parametre kvality cukrovej repy (výťažnosť rafinády: + 0,48 %, rel. 4,05 %; úroda rafinády + 0,96 t.ha-1, rel.15,86 % v porovnaní s neošetrenou kontrolou) pri trojnásobnej aplikácii Atoniku na variante C (0,25 + 0,6 + 0,6 l.ha-1). Závislosť dosiahnutých výsledkov od rôznej dávky Atoniku bola štatisticky vysoko preukazná, resp. preukazná.In the field trial carried out in 1998 and 1999 the effect of weather conditions and different Atonik doses application on sugar beet quality (refined sugar, refined sugar yield) was studied. The trial results confirmed statistically high significant effect of weather conditions on above mentioned parameters. More favourable weather conditions in 1999 influenced high significantly increasing of refined sugar (+ 0,67 %, rel. 5,53 %) and refined sugar yield (+ 0,67 t.ha-1, rel. 9,75 %) comparing to average of both 1998, 1999 years. We found out significant effect of Atonik under its three times application ( 0,25 + 0,6 + 0,6 I.ha -1 ) on refined sugar (+ 0,48 %, rel. 4,05 %) and refined sugar yield (+ 0,96 t.ha-1, rel. 15,86 %) on C variant comparing to average values of control variant in total trial period

Consistency of data on soft photon production in hadronic interactions

The glob model of Lichard and Van Hove and the modified soft annihilation model (MSAM) of Lichard and Thompson are used as a phenomenological tool for relating results from various experiments on soft photon production in high energy collisions. The total phenomenological expectation is composed of contributions from classical bremsstrahlung, the soft annihilation model and the glob model. The empirical excess above the background from hadronic decays at very small longitudinal momenta of photons is well reproduced, as well as that for transverse momenta pT >~ 10 MeV/c. Some data do not require the glob model and MSAM components in the phenomenological mixture, but do not exclude them. On the basis of consistency of all data with the total theoretical expectation we argue that the results of all experiments are mutually consistent. The models are unable to describe the excess of ultrasoft photons (pT <~ 10 MeV/c), seen by some, but not all, experiments. This may indicate an as yet unknown projectile-mass-dependent production mechanism. Possible relations of soft photon production to other phenomena are discussed. A simple-to-use, but physically equivalent version of the glob model is developed, which enables an easy check of presented results.Comment: 25 pages, RevTeX, epsf.sty, 12 embedded figure

INFLUENCE OF DIFFERENT TILLAGE SYSTEMS ON YIELD AND SELECTED QUALITATIVE PARAMETERS OF SUGAR BEET

V poľnom polyfaktorovom pokuse s cukrovou repou bol sledovaný vplyv odrôd (Fox, Zenith) a rôznych spôsobov hospodárenia na pôde (A - zber slamy, podmietka, maštaľný hnoj, stredná orba, hlboká orba, urovnanie povrchu pôdy; B - zber slamy, podmietka, zelené hnojenie, hlboká orba, urovnanie povrchu pôdy; C - podmietka so zapravením slamy, zelené hnojenie, hlboká orba, urovnanie povrchu pôdy) na jej úrodu a technologickú kvalitu. V priemere odrôd bola najvyššia úroda buliev (65,52 t.ha-1) a úroda polarizačného cukru (10,63 t.ha-1) zistená na variante hospodárenia pôdy B. Najvyššia digescia (16,46 °S) a výťažnosť rafinády (14,27 %) bola dosiahnutá na variante C. V daných pôdno-klimatických podmienkach boli významnejšie hodnoty úrody buliev (64,96 t.ha-1), digescie (16,51 °S), výťažnosti rafinády (14,43 %) a úrody polarizačného cukru (9,93 t.ha-1) zaznamenané pri odrode Zenith.The effect of varieties (Fox, Zenith) and variants of soil tillage have been observed on both the yield and technological quality of sugar beet in the field multi-factorial experiment (A - hay harvest, stubble ploughing, farmyard manuring, mean ploughing, deep ploughing, evening of soil surface; B - hay harvest, stubble ploughing, green manuring, deep ploughing, evening of soil surface; C - stubble ploughing with incorporation of hay, green manuring, deep ploughing, evening of soil surface). The highest root yield (65,52 t.ha-1) and polarised sugar yield (10,63 t.ha-1) was found on the variant B. The most significant digestion (16,46 °S) and refined sugar yield (14,27 %) was reached on variant C. In variety Zenith the highest yield of sugar beet roots (64,96 t.ha-1), digestion (16,51 °S), refined (14,43 %) and polarised sugar yields (9,93 t.ha-1) was found at given soil-climatic conditions

On the Number of Synchronizing Colorings of Digraphs

We deal with $k$-out-regular directed multigraphs with loops (called simply \emph{digraphs}). The edges of such a digraph can be colored by elements of some fixed $k$-element set in such a way that outgoing edges of every vertex have different colors. Such a coloring corresponds naturally to an automaton. The road coloring theorem states that every primitive digraph has a synchronizing coloring. In the present paper we study how many synchronizing colorings can exist for a digraph with $n$ vertices. We performed an extensive experimental investigation of digraphs with small number of vertices. This was done by using our dedicated algorithm exhaustively enumerating all small digraphs. We also present a series of digraphs whose fraction of synchronizing colorings is equal to $1-1/k^d$, for every $d \ge 1$ and the number of vertices large enough. On the basis of our results we state several conjectures and open problems. In particular, we conjecture that $1-1/k$ is the smallest possible fraction of synchronizing colorings, except for a single exceptional example on 6 vertices for $k=2$.Comment: CIAA 2015. The final publication is available at http://link.springer.com/chapter/10.1007/978-3-319-22360-5_1

Faster linearizability checking via PP-compositionality

Linearizability is a well-established consistency and correctness criterion for concurrent data types. An important feature of linearizability is Herlihy and Wing's locality principle, which says that a concurrent system is linearizable if and only if all of its constituent parts (so-called objects) are linearizable. This paper presents $P$-compositionality, which generalizes the idea behind the locality principle to operations on the same concurrent data type. We implement $P$-compositionality in a novel linearizability checker. Our experiments with over nine implementations of concurrent sets, including Intel's TBB library, show that our linearizability checker is one order of magnitude faster and/or more space efficient than the state-of-the-art algorithm.Comment: 15 pages, 2 figure

Market value margin via mean-variance hedging

We use mean–variance hedging in discrete time in order to value an insurance liability. The prediction of the insurance liability is decomposed into claims development results, that is, yearly deteriorations in its conditional expected values until the liability is finally settled. We assume the existence of a tradeable derivative with binary pay-off written on the claims development result and available in each development period. General valuation formulas are stated and, under additional assumptions, these valuation formulas simplify to resemble familiar regulatory cost-of-capital-based formulas. However, adoption of the mean–variance framework improves upon the regulatory approach by allowing for potential calibration to observed market prices, inclusion of other tradeable assets, and consistent extension to multiple periods. Furthermore, it is shown that the hedging strategy can also lead to increased capital efficiency