4,261 research outputs found
On locally polar spaces whose planes are affine
No full textWe give some contributions to the classification of geometries belonging to the following diagram: (Af. Cn) © 1990 Kluwer Academic Publishers
On a new family of flag-transitive semibiplanes
No full textEach of the d-dimensional dual hyperovals S(m)(h) discovered by Yoshiara [20] gives rise, via affine expansion, to a flag-transitive semibiplane Af (S(m)(h)). We prove that, if m + h = d + 1, then Af (S(m)(h)) is an elation semibiplane. In the other cases, if d > 2 then Af (S(m)(h)) is not isomorphic to any of the examples we are aware of, except possibly for certain semibiplanes obtained from D(n)-buildings defined over G F(2). However, many semibiplanes live hidden as quotients inside halved hypercubes. It is thus quite natural to ask whether any of our semibiplanes are like that. We prove that Af (S(m)(h)) is a quotient of a halved hypercube if and only if h = m. (C) 2001 Academic Press
Modular impulsive green monopropellant propulsion system (Mimps-g): For cubesats in leo and to the moon
No full textGreen propellants are currently considered as enabling technology that is revolutionizing the development of high-performance space propulsion, especially for small-sized spacecraft. Modern space missions, either in LEO or interplanetary, require relatively high-thrust and impulsive capabilities to provide better control on the spacecraft, and to overcome the growing challenges, particularly related to overcrowded LEOs, and to modern space application orbital maneuver requirements. Green monopropellants are gaining momentum in the design and development of small and modular liquid propulsion systems, especially for CubeSats, due to their favorable thermophysical properties and relatively high performance when compared to gaseous propellants, and perhaps simpler management when compared to bipropellants. Accordingly, a novel high-thrust modular impulsive green monopropellant propulsion system with a micro electric pump feed cycle is proposed. MIMPS-G500mN is designed to be capable of delivering 0.5 N thrust and offers theoretical total impulse ITot from 850 to 1350 N s per 1U and >3000 N s per 2U depending on the burnt monopropellant, which makes it a candidate for various LEO satellites as well as future Moon missions. Green monopropellant ASCENT (formerly AF-M315E), as well as HAN and ADN-based alternatives (i.e., HNP225 and LMP-103S) were proposed in the preliminary design and system analysis. The article will present state-of-the-art green monopropellants in the (EIL) Energetic Ionic Liquid class and a trade-off study for proposed propellants. System analysis and design of MIMPS-G500mN will be discussed in detail, and the article will conclude with a market survey on small satellites green monopropellant propulsion systems and commercial off-the-shelf thrusters.</p
Isrogrogidda Falka Af-soomaaliga: Aragti ku aadan Midaynta Qoraalkiisa
No full textQoraagu wuxuu diraasad ku sameeyey sidii loo midayn lahaa af Soomaaliga qoraaal ahaan loo adeegsada. Gaar ahaan wuxuu diiradda saarayaa sidii loo midayn lahaa qaababka isrogrogga falalka oo haatan loo adeegsado siyaabo aan midaysanayn.In questo articolo, l'autore analizza e avanza una proposta relativamente alla standardizzazione del somalo scritto, in particolar modo delle forme di coniugazione dei verbi somali che attualmente non sono scritte in modo omogenea.In this article, the author analyzes and provides a proposal about the standardization of written Somali, in particular relating to verb conjugation forms whose orthography still differs today.Cabdirashid M. Ismaaciil, Cabdalla C. Mansuur, Saynab A. Sharci (eds.
Coastal Research and its Economic Justification
No full textProper and thorough planning of coastal engineering projects is discussed and the economie justification of research work indicated. Examples are given concerning navigational problems, coastal protection problems, and harbor sediment problems.KWP-collectio
Midaynta iyo Horumarinta Af-soomaaliga
No full textQoraagu wuxuu maqaalkan ku falanqaynayaa arrimo ku saabsan midaynta af Soomaaliga qoran, oo dadka qaarkood ay ku doodaan in ay dhibaato ka taagantahay, iyagoo u aanaynaya kala duwanaanta lahjadaha Soomaaliyeed iyo farta af Soomaaliga oo aan xasillayn. Qoraha oo soo bandhigayaa in arrimahaasu aanu sax ahayn, wuxuuna muujinayaa caqabadaha dhabta ah ee hortaagan houmarinta af Soomaaliga: afku wuxuu la'yahay dawlad si rasmi ah u adeegsato, weerar ba'anna waxaa ku haya af Ingiriisiga, xagga ereyadana nabaadguur xooggan ayaa ku dhacaya, gaar ahaan ereyada la xiriira dhaqanka Soomaaliyeed.L'autore, in questo articolo, analizzando la questione della lingua somala scritta, cerca di illustrare che la situazione del somalo standard non è cosi problematica come a detta di alcuni somali, specialmente, nell'ortografia e nella differenza tra i dialetti, ma il problema somalo è bensì riscontrabile in altri fattori: la mancanza di un stato che continui ad adottare il somalo come lingua ufficiale, l'estinzione di tantissimi vocaboli in disuso, nonché la forte influenza dalla lingua inglese.The author in this article, in analysing the written somali language, wants to show the somali standard situation is not so bad, like some Somalis say, especially in orthography and in vernaculars difference. In spite of, the somali language problem is recognisable in some others factors: lack of state that usually chooses somali language as official language, extinction of many terms in disuse and also the strong influence of English.Cabdirashid M. Ismaaciil, Cabdalla C. Mansuur, Saynab A. Sharci (eds.
Om inloppet ifrån Östersjön : till SöderTelje eller Egelsta wiken
No full textAuthor: Nathanael Gerhard af Schultén.Dated: "Carlberg den 12 Januari 1806."Digital reproduction, The National Library of Finland, Centre for Preservation and Digitisation, MikkeliA description of the Baltic Sea.TravelEuropeanaSchultén, Nathanael Gerhard af (1750-1825
Dwing als gebiedsontwikkelaar een duidelijke opdracht af
No full textTerwijl de context waarin gebiedsontwikkelaars werken alleen maar complexer wordt, ziet Co Verdaas, hoogleraar gebiedsontwikkeling, een aanhoudende neiging om keuzes vooruit te schuiven of te verhullen. Hij geeft zes tips om gebiedsontwikkelaars in hun kracht te zetten. “Zonder escalatie geen resultaat zou het devies moeten zijn.”Practice Chair Urban Area Developmen
New distance regular graphs arising from dimensional dual hyperovals
No full textIn [4] we have studied the semibiplanes Sigma (e)(m,h) = Af(S-m,h(e)) obtained as affine expansions of the d-dimensional dual hyperovals of Yoshiara [6]. We continue that investigation here, but from a graph theoretic point of view. Denoting by re the incidence graph of (the point-block system of) Sigma (e)(m,h), we prove that Gamma (e)(m,h) is distance regular if and only if either m + h = e or (m + h, e) = 1. In the latter case, Gamma (e)(m,h) has the same array as the coset graph K-h(e) of the extended binary Kasami code K(2(e), 2(h)) but, as we prove in this paper, we have Gamma (e)(m,h) similar or equal to K-h(e) if and only if m = h. Finally, by exploiting some information obtained on Gamma (e)(m,h), we prove that if e less than or equal to 13 and m not equal h with (m + h, e) = 1, then Sigma (e)(m,h) is simply connected. (C) 2001 Academic Press
- …
