Theoretical model for VITA-educed coherent structures in the wall region of a turbulent boundary layer

Experiments on wall-bounded shear flows (channel flows and boundary layers) have indicated that the turbulence in the region close to the wall exhibits a characteristic intermittently formed pattern of coherent structures. For a quantitative study of coherent structures it is necessary to make use of conditional sampling. One particularly successful sampling technique is the Variable Integration Time Averaging technique (VITA) first explored by Blackwelder and Kaplan (1976). In this, an event is assumed to occur when the short time variance exceeds a certain threshold multiple of the mean square signal. The analysis presented removes some assumptions in the earlier models in that the effects of pressure and viscosity are taken into account in an approximation based on the assumption that the near-wall structures are highly elongated in the streamwise direction. The appropriateness of this is suggested by the observations but is also self consistent with the results of the model which show that the streamwise dimension of the structure grows with time, so that the approximation should improve with the age of the structure

Effect of magnetic disorder and strong electron correlations on the thermodynamics of CrN

We use first-principles calculations to study the effect of magnetic disorder and electron correlations on the structural and thermodynamic properties of CrN. We illustrate the usability of a special quasirandom structure supercell treatment of the magnetic disorder by comparing with coherent potential approximation calculations and with a complementary magnetic sampling method. The need of a treatment of electron correlations effects beyond the local density approximation is proven by a comparison of LDA+U calculations of structural and electronic properties with experimental results. When magnetic disorder and strong electron correlations are taken into account simultaneously, pressure and temperature induced structural and magnetic transitions in CrN can be understood.Comment: 23 pages, 7 figure

The simulation of coherent structures in a laminar boundary layer

Coherent structures in turbulent shear flows were studied extensively by several techniques, including the VITA technique which selects rapidly accelerating or decelerating regions in the flow. The evolution of a localized disturbance in a laminar boundary layer shows strong similarity to the evolution of coherent structures in a turbulent-wall bounded flow. Starting from a liftup-sweep motion, a strong shear layer develops which shares many of the features seen in conditionally-sampled turbulent velocity fields. The structure of the shear layer, Reynolds stress distribution, and wall pressure footprint are qualitatively the same, indicating that the dynamics responsible for the structure's evolution are simple mechanisms dependent only on the presence of a high mean shear and a wall and independent of the effects of local random fluctuations and outer flow effects. As the disturbance progressed, the development of streak-like-high- and low-speed regions associated with the three-dimensionality

The Broad-Band Spectrum and Infrared Variability of the Magnetar AXP 1E1048.1-5937

We present photometry of the Anomalous X-ray pulsar 1E1048.1-5937 in the infrared and optical, taken at Magellan and the VLT. The object is detected in the I, J and Ks bands under excellent conditions. We find that the source has varied greatly in its infrared brightness and present these new magnitudes. No correlation is found between the infrared flux and spin-down rate, but the infrared flux and X-ray flux may be anti-correlated. Assuming nominal reddening values, the resultant spectral energy distribution is found to be inconsistent with the only other AXP SED available (for 4U0142+61). We consider the effect of the uncertainty in the reddening to the source on its SED. We find that although both the X-ray and infrared fluxes have varied greatly for this source, the most recent flux ratio is remarkably consistent with what is is found for other AXPs. Finally, we discuss the implications of our findings in the context of the magnetar model.Comment: 21 pages, 5 eps figures. Submitted to Ap

Sausu - Malonas - Tolai ou les leçons d'une transmigration réussie : étude agro-économique de 3 Centres de Transmigration dans la Province de Sulawesi Tengah

Cette étude concerne 3 centres de transmigration situés à Sulawesi Centre : Sausu,Malonas,Tolai.L'essentiel des données de base a été obtenu auprès des transmigrants.Un échantillon de 160 familles de colons a été suivi par enquête en quatre passages répétés espacés de 2 mois et observation sur le terrain.En Indonésie,les transferts de population commencés sous l'administration coloniale hollandaise avaient pour objectifs de réduire les déséquilibres démographiques entre les différentes iles.En 1980,la densité de population était de 690 habitants au km2 à Java et de 18 km2 à Sulawesi Centre.Dans la première partie de cette étude,les auteurs analysent l'origine,les motivations des transmigrants,ce qui fait l'originalité des 3 Centres qui jouissent d'un environnement favorable du point de vue de la pluviométrie,du relief,de la fertilité du sol.Pour chacun des centres,il est signalé les surfaces cultivées,les cultures adoptées (riz,soja) et les revenus dont bénéficient les transmigrants grace aux activités agricoles et non agricoles.Dans la dernière partie,les auteurs analysent les causes de certains échecs et des succès de l'opération en signalant le nombre trés important des transmigrants spontanés dans cette région et présentent des recommandations pour l'avenir

Urban Planning and Natural Hazard Governance

The establishment of effective linkages between institutional urban planning and disaster risk strategies remains a challenge for formal governance structures. For governments at all administrative scales, disaster resilience planning has required systemic capacities that rely on structures of governance, humanitarian frameworks, and budgetary capacities. However, with growing urbanization trends, humanitarian responses and Disaster Risk Management (DRM) frameworks have had to adapt their operations in contexts with high population density, complex infrastructure systems, informal dynamics, and a broader range of actors. Urban areas concentrate an array of different groups with the capability of contributing to urban responses and strategies to cope with disaster effects, including community groups, government agencies, international organizations and humanitarian practitioners. In addition, cities have running planning structures that support their administration and spatial organization, with instruments that supply constant information about population characteristics, infrastructure capacity and potential weaknesses. Processes and data ascribed to urban planning can provide vital knowledge to natural hazard governance frameworks, from technical resources to conceptual approaches towards spatial analysis. Authorities managing risk could improve their strategic objectives if they could access and integrate urban planning information. Furthermore, a collaborative hazard governance can provide equity to multiple urban actors that are usually left out of institutional DRM, including nongovernmental organizations, academia, and community groups. Traditional top-down models can operate in parallel with horizontal arrangements, giving voice to groups with limited access to political platforms but who are knowledgeable on urban space and social codes. Their still limited recognition is evidence that there is still a disconnect between the intentions of global frameworks for inclusive governance, and the co-production of an urban planning designed for inclusive resilience

Implementasi Kerja Sama Indonesia-amerika Serikat Dalam Counter Terrorism: Hasil Program Diplomatic Security Service Antiterrorism Assistance Terhadap Kasus Terorisme Di Indonesia Tahun 2003-2014

Since the events of 9/11 were carried out Al-Qaeda group in the United States,the world back on to remind you that the crime of terrorism can be doneanytime and anywhere. Al-Qaeda group led by Osama bin Laden wanted toattack the United States and its allies to fight the oppression of Muslims bydeveloping a network to Indonesia. Groups in Indonesia who are convicted ofterrorism and has a style of thinking is similar to Al-Qaeda, namely JamaahIslamiyah, Jemaah Ansharut Tauhid, East Indonesian Mujahedeen and WestIndonesian Mujaheddin. In response to the terrorist acts, Indonesia incooperation with the United States to train law enforcement personnel of theRepublic of Indonesia is in the DSS/ATA (Diplomatic Security ServiceAntiterrorism Assistance). Literature and interviewing is a method to knowthe progress of the implementation of the cooperation. The initial results ofthis study showed that less than the maximum implementation of thiscooperation because there is some training that is not in its implementation.Then it can be concluded that the initial results of the study showed a negativecorrelation with the end result of research which states that the cooperationin the program DSS/ATA has been running well since the training has notbeen implemented yet due to terrorism cases should be dealt with using thetraining. After analysis, the authors also provide recommendations forcooperation between Indonesia and the United States in the DSS/AT