Super-regular Steiner 2-designs

A design is additive under an abelian group G (briefly, G-additive) if, up to isomorphism, its point set is contained in G and the elements of each block sum up to zero. The only known Steiner 2-designs that are G-additive for some G have block size which is either a prime power or a prime power plus one. Indeed they are the point-line designs of the affine spaces AG(n,q), the point-line designs of the projective planes PG(2,q), the point-line designs of the projective spaces PG(n,2) and a sporadic example of a 2-(8191,7,1) design. In the attempt to find new examples, possibly with a block size which is neither a prime power nor a prime power plus one, we look for Steiner 2-designs which are strictly G-additive (the point set is exactly G) and G-regular (any translate of any block is a block as well) at the same time. These designs will be called “G-super-regular”. Our main result is that there are infinitely many values of v for which there exists a super-regular, and therefore additive, 2-(v,k,1) design whenever k is neither singly even nor of the form 2n3≥12. The case k≡2 (mod 4) is a genuine exception whereas k=2n3≥12 is at the moment a possible exception. We also find super-regular 2-(pn,p,1) designs with p∈{5,7} and n≥3 which are not isomorphic to the point-line design of AG(n,p)

Partitioned difference families: the storm has not yet passed

Two years ago, we alarmed the scientific community about the large number of bad papers in the literature on zero difference balanced functions, where direct proofs of seemingly new results are presented in an unnecessarily lengthy and convoluted way. Indeed, these results had been proved long before and very easily in terms of difference families. In spite of our report, papers of the same kind continue to proliferate. Regrettably, a further attempt to put the topic in order seems unavoidable. While some authors now follow our recommendation of using the terminology of partitioned difference families, their methods are still the same and their results are often trivial or even wrong. In this note, we show how a very recent paper of this type can be easily dealt with

CCD photometry of 2060 Chiron, 1991 January

Observations of 2060 Chiron was performed on 7 to 8 Jan. 1991 with the Mt. Palomar 1.52 m telescope in the Gunn-R passband. On-chip field stars were used to perform differential reductions. The repeatability of the 5.9 hour light curve was excellent, both within a night and from night to night. No evidence for short-term secular variations similar to those seen last year by both Luu and Jewitt (1990) and Buratti and Dunbar (1991) is seen in the new light curve. Chiron's rotational light curve appears strikingly similar to that obtained a year earlier by Luu and Jewitt (1990), both in amplitude and shape. Both light curves show strongly correlated changes over a timescale of perhaps 15 minutes. These same features were marginally visible in the 1986 light curve. Such behavior is believed to be evidence that Chiron may be more aspherical than the 4 percent intensity variation might otherwise indicate, and favors a viewing geometry where the subearth latitude is rather low. Chiron was much fainter in 1985, when a partial light curve was obtained by Marcialis. Due to the lower sampling rate of these early data, no conclusions can be made regarding the high-frequency light curve structure back then. All three of these light curves differ significantly from that obtained by Buratti and Dunbar (1991), one week before the observations of Luu and Jewitt. The Chiron field was calibrated using Landolt standards on Ut 15 Mar. 1991. A mean R-magnitude of 15.6 + or - 0.1 was found. Variability of 2060 Chiron was demonstrated over timescales of minutes, hours, and years. An intense campaign was urged to monitor the photometric behavior of Chiron throughout the 1990s

Apprendistato: quadro comparato e buone prassi

Il volume affronta da un punto di vista comparato gli aspetti principali connessi al contratto di apprendistato. Il punto di partenza sono le analisi e gli spunti offerti dalle istituzioni comunitarie per una maggiore diffusione dei rapporti di apprendistato, in un’ottica di aumento dell’occupazione giovanile e di contrasto alla dispersione scolastica. La pubblicazione mette in relazione cinque aspetti: definizione e ruolo dell’apprendistato; soggetti regolatori; retribuzione; durata del percorso; monte ore formativo. Per ciascuna di queste voci si evidenziano le peculiarità dei sistemi in vigore in Italia, Francia, Spagna, Regno Unito, Germania, Danimarca e Svezia

Thermal Comfort Evaluation Within Non-residential Environments: Development of Artificial Neural Network by Using the Adaptive Approach Data☆

Abstract A new algorithm for the PMV calculation was developed using Artificial Neural Networks. Several experimental investigations were carried out in two classrooms using both Fanger static model and adaptive approaches for the PMV evaluation. The Artificial Neural Network was trained considering a few input parameters; specifically for the network development only the air temperature and relative humidity were considered as experimental data. This algorithm allows to correlate the thermal sensation to both indoor and outdoor factors and it is a useful tool for predicting the PMV index, replacing the traditional methods with less time and cost demanding

Proposal for a Data Visualization and Assessment System to Rebalance Landscape Quality

The landscape can be considered a complex system described as a non-linear entity, organized accord- ing to the connections between the different elements that characterize its state. The latter cannot be determined a priori but emerges from the multiple interactions between assets and relationships that are no longer found when the phenomenon is traced back to the individual components. Territorial development is closely connected to social, economic, cultural and symbolic issues that determine the transformative practices of space and the territorial palimpsest. If not carefully managed, these forces can lead to the dissolution of the landscape and environmental values that have been stratified in a specific land. This paper proposes the construction of a numerical spatial model that describes the territorial settlement patterns, based on methodologies and techniques typical of AI, to develop tools for re-balancing the man-landscape relationship

Detecting Seasonal Volatile Transport on Triton through Photometric Observations

More than 35 million people in the western United States depend on the Colorado River as a Broadband Photometry will be obtained to provide data on Triton. Our data will be collected over a series of nights of time-resolved Bessel BVRI photometry using the 0.6-m telescope at the JPL Table Mountain Observatory (TMO) located in Wrightwood, California. The objective of these observations is to detect and measure volatile transport on Triton. The vapor pressures of nitrogen and methane vary over the seasonal cycles of Triton and Pluto. The seasonal migration of frost can be detected by a combination of changes in the rotational lightcurve. Previous work of Triton has shown that these exhibit the transport of volatiles on their surfaces. The purpose of acquiring another lightcurve is to determine whether volatile transport is still occurring and to track it. Our current goal is to fill in the missing longitudes that we not obtained during our last observations of Triton. Our previous work detected an opposition surge for the first time, and these observations will allow us to further characterize it. Our goal is to create detailed and longer-term comparisons of our data with Voyager images and other volatile-transport models. With our measurements and ground-based data of Pluto and Triton, we will hopefully have a greater understanding of seasonal volatile transport on Kuiper Belt Objects. This understanding will help us predict, search for, model, and possibly observe seasonal changes on other Kuiper Belt Objects

Broadband Photometry of Pluto

Broadband Photometry was obtained to provide data on Pluto, discovered on January 23, 1930 by Clyde W. Tombaugh at Lowell Observatory in Flagstaff, Arizona. Our data was collected over a series of four nights of time-resolved Bessel BVRI photometry using the 0.6-m telescope at the JPL Table Mountain Observatory (TMO) located in Wrightwood, California. Our collected data will complement the data obtained by the New Horizons mission to calculate Pluto’s solar phase curve at opposition. The primary objective of our work will be to analyze the solar phase curve of Pluto while it is at opposition. Our work will help in understanding Pluto. It will also provide evidence for seasonal transportation of volatiles within Pluto’s atmosphere. Our data will be analyzed through various programs, where we will use both biases and sky-flats to make any correction to the images of Pluto we’ve obtained (i.e debris). Once we have analyzed the data, we will be able to calculate and plot Pluto’s solar phase curve. Our data will be used to complement the data obtained by the New Horizons mission and possibly answer questions regarding the seasonal transport of volatiles as found on Pluto, as well as the albedo patterns