291 research outputs found

    Consecutive patterns in restricted permutations and involutions

    Get PDF
    It is well-known that the set In\mathbf I_n of involutions of the symmetric group Sn\mathbf S_n corresponds bijectively - by the Foata map FF - to the set of nn-permutations that avoid the two vincular patterns 123,\underline{123}, 132.\underline{132}. We consider a bijection Γ\Gamma from the set Sn\mathbf S_n to the set of histoires de Laguerre, namely, bicolored Motzkin paths with labelled steps, and study its properties when restricted to Sn(123,132).\mathbf S_n(1\underline{23},1\underline{32}). In particular, we show that the set Sn(123,132)\mathbf S_n(\underline{123},{132}) of permutations that avoids the consecutive pattern 123\underline{123} and the classical pattern 132132 corresponds via Γ\Gamma to the set of Motzkin paths, while its image under FF is the set of restricted involutions In(3412).\mathbf I_n(3412). We exploit these results to determine the joint distribution of the statistics des and inv over Sn(123,132)\mathbf S_n(\underline{123},{132}) and over In(3412).\mathbf I_n(3412). Moreover, we determine the distribution in these two sets of every consecutive pattern of length three. To this aim, we use a modified version of the well-known Goulden-Jacson cluster method.Comment: 24 page

    Derivation of Land Surface Temperature from MODIS Data Using the General Split Window Technique

    Get PDF
    Fast Atmospheric Signature Code (FASCODE), a line-by-line radiative transfer programme, was used to simulate Moderate Resolution Imaging Spectroradiometer (MODIS) data at wavelengths 11.03 and 12.02 mm to ascertain how accurately the land surface temperature (LST) can be inferred, by the split window technique (SWT), for a wide range of atmospheric and terrestrial conditions. The approach starts from the Ulivieri algorithm, originally applied to Advanced Very High Resolution Radiometer (AVHRR) channels 4 and 5. This algorithm proved to be very accurate compared to several others and takes into account the atmospheric effects, in particular the water vapour column (WVC) amount and a non-unitary surface emissivity. Extended simulations allowed the determination of new coefficients of this algorithm appropriate to MODIS bands 31 and 32, using different atmospheric conditions. The algorithm was also improved by removing some of the hypothesis on which its original expression was based. This led to the addition of a new corrective term that took into account the interdependence between water vapour and non-unitary emissivity values and their effects on the retrieved surface temperature. The LST products were validated within 1K with in situ LSTs in 11 cases

    Germano Sartelli

    Get PDF
    Libro-catalogo della mostra sugli artisti imolesi che hanno partecipato alle Biennali Internazionali d'arte di Venezia. Capitolo dedicato all'opera dello scultore Germano Sartelli, tra i principali esponenti dell'informale italiano

    Comparison of Bioactive Substances Content between Commercial and Wild-Type Isolates of Pleurotus eryngii

    Get PDF
    Mushrooms belonging to Pleurotus genus have been demonstrated to have important nutritional and medicinal value and their regular intake prevent many diseases, reduce the infection probability and increase immunity. In order to investigate the bioactive compounds produced by seven commercial (‘142 F’, ‘142 E’, ‘D+’, ‘V turbo’, ‘V 142’, ‘A 12’, ‘V 160’) and five wild-type (‘Albino 1107’, ‘Altamura 1603’, ‘Muro Lucano 139’, ‘Conversano 1250’, ‘Albino beige chiaro 1094’) P. eryngii isolates, the following qualitative analyses were performed: Total polyphenol content, antioxidant activity (EC50 of ABTS) and antiradical power (ARP) in fresh lyophilized and dry basidioma, and water content, -glucans and phenolic compounds in fresh samples. Standard methods were employed for each of the above mentioned aims. Total polyphenol content was diverse among the P. eryngii isolates. In particular, an elevated polyphenolic content was found in fresh lyophilized P. eryngii samples of the commercial isolates ‘V 142’ followed by ‘A 12’. The highest antiradical activity (ARP) was obtained by ‘Muro Lucano 139’ isolate. Wild P. eryngii isolates were characterized by higher water and -glucans contents compared to the commercial ones, and the highest values were registered for the ‘Albino beige chiaro 1094’ isolate. In conclusion, the present study allowed us to identify the commercial and wild-type P. eryngii isolates from the Basilicata region, with high nutritional and medicinal value based on their bioactive compounds

    Standardizing Navigation Data: A Status Update

    Get PDF
    This paper presents the work of the Navigation Working Group of the Consultative Committee for Space Data Systems (CCSDS) on development of standards addressing the transfer of orbit, attitude and tracking data for space objects. Much progress has been made since the initial presentation of the standards in 2004, including the progression of the orbit data standard to an accepted standard, and the near completion of the attitude and tracking data standards. The orbit, attitude and tracking standards attempt to address predominant parameterizations for their respective data, and create a message format that enables communication of the data across space agencies and other entities. The messages detailed in each standard are built upon a keyword = value paradigm, where a fixed list of keywords is provided in the standard where users specify information about their data, and also use keywords to encapsulate their data. The paper presents a primer on the CCSDS standardization process to put in context the state of the message standards, and the parameterizations supported in each standard, then shows examples of these standards for orbit, attitude and tracking data. Finalization of the standards is expected by the end of calendar year 2007

    Effect of base–acid properties of the mixtures of water with methanol on the solution enthalpy of selected cyclic ethers in this mixture at 298.15 K

    Get PDF
    The enthalpies of solution of cyclic ethers: 1,4- dioxane, 12-crown-4 and 18-crown-6 in the mixture of water and methanol have been measured within the whole mole fraction range at T = 298.15 K. Based on the obtained data, the effect of base–acid properties of water– methanol mixtures on the solution enthalpy of cyclic ethers in these mixtures has been analyzed. The solution enthalpy of cyclic ethers depends on acid properties of water– methanol mixtures in the range of high and medium water contents in the mixture. Based on the analysis performed, it can be assumed that in the mixtures of high methanol contents, cyclic ethe

    Mission analysis for two potential asteroids threat scenarios: Optimal impact strategies and technology evaluation

    Get PDF
    The Space Mission Planning Advisory Group SMPAG's mission is to prepare for an international response to a Near Earth Object impact threat through the exchange of information, development of options for collaborative research and mission opportunities, and to conduct Near Earth Object (NEO) impact threat mitigation planning activities. This paper presents the preliminary work performed by the Italian Space Agency Delegation for defining few reference missions for different NEO-threat scenarios and carrying out Phase 0 studies. In this paper two scenarios are identified to study the possible response in case of a real NEO-threat. A direct and resonant impact scenario for an asteroid deflection mission are identified resembling to the asteroid 2010RF12 but with an increased asteroid mass. Then the mission analysis and spacecraft design for the direct impact case is performed and the results discussed

    Adaptive thrust vector control during on-orbit servicing

    Get PDF
    On-orbit servicing missions often include a final propulsive phase where a spacecraft pushes the other one towards a different orbit. Specifically this is the case of the debris grasping mission where the chaser, after capturing the target by means of robotic arms, has to perform a de-orbit operation. The large thrust involved needs a perfect alignment with respect to the center of mass or the system composed by chaser and target, in order to avoid attitude changes. Such accurate alignment is quite difficult to achieve especially when the characteristics of the target are not perfectly known. A procedure is proposed in this paper, allowing a complete estimation of the center of mass position and of the moments of inertia of the system, starting from the data obtained by the gyros mounted on board of the spacecraft. The output is used to design a maneuver for correcting the target and chaser relative position by moving the robotic arms. Numerical simulations show the proficiency and the applicability of the estimation algorithm and of re-alignment maneuver to a selected mission scenario
    corecore