Applicazioni di modelli di incidentalita' potenziale per la progettazione delle rotatorie

In Italia, come in molti altri paesi europei (eccezione fatta per Francia ed Inghilterra dove la sperimentazione delle intersezioni circolari iniziò intorno agli anni '20), l’ introduzione dello schema a rotatoria ebbe inizio nei primi anni '80. Tale infrastruttura ha, però, una storia più che centennale: il sistema di circolazione rotatorio a senso unico fu infatti proposto per la prima volta nel 1903, per il Columbus Circle di New YorK City, dall’ ingegnere William Phelps Eno, “il padre della regolazione del traffico”. Altre piazze circolari esistevano prima di tale data; tuttavia esse erano concepite come particolarità architettoniche all’ interno delle quali era permessa la circolazione a doppio senso attorno all’ isola centrale. Inoltre, William Phelps Eno fu il primo a proporre la precedenza ai veicoli circolanti sull’ anello, dato che sulle prime rotatorie vigeva la regola del “dare precedenza a destra”. Eno può quindi essere ritenuto il promotore, sia degli schemi di percorrenza a senso unico sia delle modalità di circolazione in rotatoria. L’ intersezione circolare costituisce una delle più interessanti e moderne tipologie per la sistemazione delle intersezioni stradali. Infatti, oltre alle ottime prestazioni in termini di funzionalità (capacità, ritardi, lunghezza delle code) vanno sottolineate le caratteristiche intrinseche di sicurezza che tale tipo di schema possiede; questo ultimo aspetto è una conseguenza delle seguenti migliorie: riduzione dei punti di conflitto. Tale fatto risulta evidente considerando una nodo, a quattro bracci, di una rete stradale: un eventuale sistemazione con incrocio tradizionale porta ad avere, tra le possibili traiettorie dei veicoli, 32 punti potenziali di conflitto mentre l’ utilizzo di uno schema a rotatoria riduce tale numero a 8; assenza di conflitti di attraversamento. Ad essi sono associati gli incidenti più pericolosi: frontali e ad angolo retto; riduzione della velocità di percorrenza e delle differenze di velocità tra i veicoli che sono coinvolti nella collisioni. Le traiettorie imposte dalla geometria dello schema presentano raggi di curvatura tali da ridurre le velocità, sia sull’ anello che sugli ingressi. La conseguenza di tutto ciò è che, se confrontiamo i tassi di incidentalità delle intersezioni tradizionali, semaforizzate e non, con quelli delle rotatorie, possiamo osservare differenze notevoli a vantaggio delle ultime. Si riscontra anche una minore pericolosità delle collisioni, cioè un minor numero di sinistri con danni alle persone sul totale di incidenti. Sono tutti questi motivi che fanno dirigere, sia in progetto sia in riqualificazione, verso la scelta della rotatoria come possibile sistemazione

Datura stramonium L. Tatula – invazivni korov na području Mačve i zapadnog Srema

The aim of this paper is to indicate the permanency degree changes of Datura stramonium, appeared because of many years of herbicides usage, global environmental changes and modern farming methods. The region of Mačva covers the area of 860km2, while the total area of Western Srem is approx. 762km2. The most represented field crop, on both tested regions, is corn. Datura is an annual late spring weed ( T4 ). Since the corn was previously sowed in the middle and at the end of April, herbicides could effect on late spring weeds and root crops. Due to global environmental changes, the time for corn sowing moved to the end of March and beginnng of April, as well as the usage of soil herbicides. Because of decreased herbicide effects on late spring weeds and moving the time of sowing, the growth of this weed sort during the last 15 years for approx. 33%, can be explained ( shown in Table 1 ). Datura is an invasive weed that appears in root crops and ruderal habitats ( rich of organic matters and nitrogen ). The main goal of supressing must be preventing Datura seed bringing. The measures of supressing can be divided into two groups: modern farming and chemical methods. As for modern farming methods, the attention must be paid to repeated growing, especially to crop rotation. When ruderal habitats are in question, mowing must be regularly done, as well as using total herbicides ( Glyphosate ).Fitocenološki snimci pravljeni su 1970, 1977, 1989, 2007. i 2013. godine na području Mačve u okopavinama, dok je na području zapadnog Srema pravljen 2013. godine. Cilj rada je da ukaže na promene stepena stalnosti ove biljne vrste, nastale zbog višegodišnje primene herbicida, globalnih klimatskih promena i primene agrotehnike

Kinship as a Strategy for Living: Screening the Queer “Family”

The evolving representations of queer people in moving images have taken the form of a homecoming, especially in light of recent law changes that pertain to same-sex marriage in the United States, and the media’s concurrent readiness to recast sexual minorities in the roles of husbands, wives, fathers, mothers and children. The queers’ cinematic and televisual journey from periphery to center has effectively become a journey back to the privileges and comforts of familial life, and a domesticity that remains at the core of American culture. In light of this transition, this thesis seeks to explore the presence of kinship in queer urban communities in the period from the 1970s to the 1990s. While the queer cultural output of this period seeks to establish the queer identity independent of, or in opposition to, heteronormativity, the idea of family is absorbed and transformed as part of a larger community-building process. In the queer milieu, family is appropriated, emulated and enacted as much as it is escaped, negotiated and subverted. In order to demonstrate the diversity of the queer “family,” this study engages with three major filmic case studies –The Boys in the Band (dir. William Friedkin, 1970), Parting Glances (dir. Bill Sherwood, 1986) and Paris Is Burning (dir. Jennie Livingston, 1990). These films are analyzed for their capacity to give shape to queer kinship as conceptualized in queer theory, film theory, queer history and criticism, psychoanalysis, and dramatic theories. Through these filmic case studies, the queer “family” is located and investigated in three distinct contexts – that of American family drama, the AIDS epidemic and performance documentary

Abutilon theophrasti Medic. Teofrastova Lipica - invazivna korovska vrsta na području Mačve, Srema i Semberije

The subject of this paper is to indicate the permanence degree changes of Abutilon theophrasti Medic, appeared as a consequence of irregular usage of herbicides, environmental changes, as well as the applying different modern farming methods. The region of Mačva coversthe area of approx. 80000 ha, with different types of soil, and with corn as the most represented field crops. The area of Western Srem is about 762 km2, it has more types of soil which enables an intensive agricultural production, but mostly sown is corn. The total amount of arable land in Semberija is approx. 54000 ha, and the most represented agricultural cultures are granaries ( wheat, corn, barley ). Although the great estattention, in the sense of modern farming methods, is paid to the field crops grown on the testing territories, corn sowing in monoculture, excessive usage of herbicides, reduced primary processing, as well as global environmental changes, led to the extremely frequent appearance of Abutilon theophrasti , that was not present in such amount before. Velvetleaf is anannual plant, terophit (T4), belonging to late spring weeds. On the basis of the results obtained from this paper, it can be concluded that fertile and rich land of Mačva is the most suitable for Velvetleaf being a nitrophilous plant (N4). Bad climate conditions, during the period of sowing field crops in the past few years, contributed to the late sowing, as well as using some modern farming methods and the usage of herbicides. The results obtained from the territory of Western Srem and Semberija, being rather less than those from Mačva, indicate the importance of modern farming methods and crop rotation in order to suppress this invasive weed type. Speaking of the already mentioned territories and because of a more suitable climate, they are done timely and completely.Fitocenološki snimci su pravljeni 2008. godine na području Mačve, Srema i Semberije, u okopavinama na većem broju lokaliteta. Nepravilna i neracionalna upotreba herbicida je znatno doprinela izmeni kvantitativnog i kvalitativnog sastava korovskih zajednica na istraživanim područjima. Cilj ovog rada je da ukaže na promene stepena stalnosti Abutilon theophrasti Medic. nastale kao posledica takve upotrebe herbicida, klimatskih promena, kao i primene različitog stepena agrotehnike

Tamm oscillations in semi-infinite nonlinear waveguide arrays

We demonstrate numerically the existence of nonlinear Tamm oscillations at the interface between a substrate and one-dimensional waveguide array with both cubic and saturable, self-focusing and self-defocusing nonlinearity. Light is trapped in the vicinity of the boundary of the array due to the interplay between the repulsive edge potential and Bragg reflection inside the array. In the special case when this potential is linear these oscillations reduce themselves to surface Bloch oscillations.Comment: e.g.: 4 pages, 4 figures, submitted to Phys. Rev. Let

Fano resonances in saturable waveguide arrays

We study a waveguide array with an embedded nonlinear saturable impurity. We solve the impurity problem in closed form and find the nonlinear localized modes. Next, we consider the scattering of a small-amplitude plane wave by a nonlinear impurity mode, and discover regions in parameter space where transmission is fully suppressed. We relate these findings with Fano resonances and propose this setup as a mean to control the transport of light across the array.Comment: 3 pages, 4 figures, submitted to Optics Letter