A thermodynamical fiber bundle model for the fracture of disordered materials

We investigate a disordered version of a thermodynamic fiber bundle model proposed by Selinger, Wang, Gelbart, and Ben-Shaul a few years ago. For simple forms of disorder, the model is analytically tractable and displays some new features. At either constant stress or constant strain, there is a non monotonic increase of the fraction of broken fibers as a function of temperature. Moreover, the same values of some macroscopic quantities as stress and strain may correspond to different microscopic cofigurations, which can be essential for determining the thermal activation time of the fracture. We argue that different microscopic states may be characterized by an experimentally accessible analog of the Edwards-Anderson parameter. At zero temperature, we recover the behavior of the irreversible fiber bundle model.Comment: 18 pages, 10 figure

A damage model based on failure threshold weakening

A variety of studies have modeled the physics of material deformation and damage as examples of generalized phase transitions, involving either critical phenomena or spinodal nucleation. Here we study a model for frictional sliding with long range interactions and recurrent damage that is parameterized by a process of damage and partial healing during sliding. We introduce a failure threshold weakening parameter into the cellular-automaton slider-block model which allows blocks to fail at a reduced failure threshold for all subsequent failures during an event. We show that a critical point is reached beyond which the probability of a system-wide event scales with this weakening parameter. We provide a mapping to the percolation transition, and show that the values of the scaling exponents approach the values for mean-field percolation (spinodal nucleation) as lattice size $L$ is increased for fixed $R$. We also examine the effect of the weakening parameter on the frequency-magnitude scaling relationship and the ergodic behavior of the model

A redshift - observation-time relation for gamma-ray bursts: evidence of a distinct sub-luminous population

We show how the redshift and peak-flux distributions of gamma-ray bursts (GRBs) have an observation time dependence that can be used to discriminate between different burst populations. We demonstrate how observation time relations can be derived from the standard integral distributions and that they can differentiate between GRB populations detected by both the BATSE and \emph{Swift} satellites. Using \emph{Swift} data we show that a redshift--observation-time relation (log\,$Z$\,--\,log\,$T$) is consistent with both a peak-flux\,--\,observation time relation (log\,$P$\,--\,log\,$T$) and a standard log\,$N$\,--\,log\,$P$ brightness distribution. As the method depends only on rarer small-$z$ events, it is invariant to high-$z$ selection effects. We use the log\,$Z$\,--\,log\,$T$ relation to show that sub-luminous GRBs are a distinct population occurring at a higher rate of order $150^{+180}_{-90} \mathrm{Gpc}^{-3}\mathrm{yr}^{-1}$. Our analysis suggests that GRB 060505 -- a relatively nearby GRB observed without any associated supernova -- is consistent with a sub-luminous population of bursts. Finally, we suggest that our relations can be used as a consistency test for some of the proposed GRB spectral energy correlations.Comment: Accepted by MNRA

Gravitational wave background from sub-luminous GRBs: prospects for second and third generation detectors

We assess the detection prospects of a gravitational wave background associated with sub-luminous gamma-ray bursts (SL-GRBs). We assume that the central engines of a significant proportion of these bursts are provided by newly born magnetars and consider two plausible GW emission mechanisms. Firstly, the deformation-induced triaxial GW emission from a newly born magnetar. Secondly, the onset of a secular bar-mode instability, associated with the long lived plateau observed in the X-ray afterglows of many gamma-ray bursts (Corsi & Meszaros 2009a). With regards to detectability, we find that the onset of a secular instability is the most optimistic scenario: under the hypothesis that SL-GRBs associated with secularly unstable magnetars occur at a rate of (48; 80)Gpc^{-3}yr^{-1} or greater, cross-correlation of data from two Einstein Telescopes (ETs) could detect the GW background associated to this signal with a signal-to-noise ratio of 3 or greater after 1 year of observation. Assuming neutron star spindown results purely from triaxial GW emissions, we find that rates of around (130;350)Gpc^{-3}yr^{-1} will be required by ET to detect the resulting GW background. We show that a background signal from secular instabilities could potentially mask a primordial GW background signal in the frequency range where ET is most sen- sitive. Finally, we show how accounting for cosmic metallicity evolution can increase the predicted signal-to-noise ratio for background signals associated with SL-GRBs.Comment: Accepted by MNRA

L'Italia agricola odierna

- Indice #9- Territorio e clima #15- La produzione agraria dal 1860 al 1880 #46- La politica agraria del Governo Fascista #148- Il patto colonico #269- La ricostruzione economica del Paese #38

Il costo della guerra europea : spese e perdite, mezzi di fronteggiarle

Note biografiche: Virgìlii, Filippo. - Statistico (Montefestino, Modena, 1865 - Roma 1950), prof. nell'università di Siena (dal 1893), di cui fu anche rettore e prof. emerito, condirettore di Studi senesi. Si occupò soprattutto di demografia, ma anche di sociologia, economia e scienza delle finanze. [da Enciclopedia Treccani]L’A. illustra, con uno studio statistico, le spese, le perdite prodotte dalla guerra e i mezzi per far loro fronte. Nella prima parte l’A. descrive il costo della guerra dopo il periodo napoleonico, dal 1828 (guerra russo-turca) fino alle guerre balcaniche con una ricchezza di dati statistici che non appesantiscono la lettura. Elenca ed esanima gli elementi che determinano il costo della guerra, quali il mantenimento del soldato, il ristagno della produzione, la paralisi del commercio mondiale, la perdita delle navi da guerra e mercantili, il valore della proprietà privata e la perdita del capitale umano. Nella seconda parte discute i mezzi per far fronte alle spese di guerra. La conclusione alla quale giunge che gli Stati belligeranti che sono maggiormente colpiti dalla guerra sono la Russia e la Francia, seguono poi l’Italia e l’Inghilterra. Non sono considerati in questo studio il Belgio, la Serbia, la Turchia, la Bulgaria

DESA1002 'Continuous City' Benjamin Virgilii

Pavilon Vivant My building is called Pavilon Vivant which in the french language means Living Pavilon. The reason why it is a living pavilion is because the user of the building uses two parts of the building. The façade half of the building is an atrium with 7 levels. These seven levels are filled with stores, bars, gyms and pools. This is accompanied by the second half of the building which is filled with 6 capsules per level. These capsules can be hired out from 2 hours to weeks and are beneficial for not only people recovering from the pools or from the bars but also people from the adjacent schools and libraries for study purposes and so on. I chose the corner of my existing site plan to design this living pavilion because I believe the corner of any block gets the most attention. Furthermore, the entries help this attention as there is no dignified entry. All three street facades have no doors or windows and is open to anyone from the public. This is accompanied with restaurants and café’s upon entry to attract new comers who have not heard of the building before. I chose to design an atrium façade as it provides interesting views from street view and beyond. The glass from the atrium allows u to see into the life of the building and also the capsules beyond giving the overall building aesthetic an interesting feel, giving the person an urge to wander into the buildings circulation. Lastly, the last important feature and brief towards my pavilion is the fact that the liftcore of the building has been presented as the main feature of the building, moreso than the capsules themselves. This is because the lifcore ventures through the pool allowing people in the lift, people in the pool and people on the pool deck a never before seen experience