178 research outputs found
Modeling and generating moving trees from video
We present a probabilistic approach for the automatic production of tree models with convincing 3D appearance and motion. The only input is a video of a moving tree that provides us an initial dynamic tree model, which is used to generate new individual trees of the same type. Our approach combines global and local constraints to construct a dynamic 3D tree model from a 2D skeleton. Our modeling takes into account factors such as the shape of branches, the overall shape of the tree, and physically plausible motion. Furthermore, we provide a generative model that creates multiple trees in 3D, given a single example model. This means that users no longer have to make each tree individually, or specify rules to make new trees. Results with different species are presented and compared to both reference input data and state of the art alternatives
Constraints on the mass and abundance of black holes in the Galactic halo: the high mass limit
We establish constraints on the mass and abundance of black holes in the
Galactic halo by determining their impact on globular clusters which are
conventionally considered to be little evolved. Using detailed Monte Carlo
simulations and simple analytic estimates, we conclude that, at Galactocentric
radius R~8 kpc, black holes with masses M_bh >~(1-3) x 10^6 M_sun can comprise
no more than a fraction f_bh ~ 0.025-0.05 of the total halo density. This
constraint significantly improves those based on disk heating and dynamical
friction arguments as well as current lensing results. At smaller radius, the
constraint on f_bh strengthens, while, at larger radius, an increased fraction
of black holes is allowed.Comment: 13 pages, 10 figures, revised version, in press, Monthly Notice
Superradiance by mini black holes with mirror
The superradiant scattering of massive scalar particles by a rotating mini
black hole is investigated. Imposing the mirror boundary condition, the system
becomes the so called black-hole bomb where the rotation energy of the black
hole is transferred to the scattered particle exponentially with time. Bulk
emissions as well as brane emissions are considered altogether. It is found
that the largest effects are expected for the brane emission of lower angular
modes with lighter mass and larger angular momentum of the black hole.
Possibilities of the forming the black-hole bomb at the LHC are discussed.Comment: 20 pages, 2 figures, 7 tables. More discussions. To appear in JHE
A REPORT BY THE ALL - PARTY PARLIAMENTARY GROUP ON A FIT AND HEALTHY CHILDHOOD THE IMPACT OF SOCIAL AND ECONOMIC INEQUALITIES ON CHILDRENâS HEALTH
A child born into circumstances of social and economic inequality in the 21st century United Kingdom will start life with one hand tied behind their back. Nowhere is the disparity of experience more marked than in that of health and this, in turn, impacts the entire life course. In the same way that priority is given to securing the national infrastructure, prioritising the health of children from all areas and in all circumstances from the outset would therefore seem to be prudent rather than profligate. Yet as this Report demonstrates,successive Governments have skimped rather thansaved; failedto build upon existing policy and played a costly policy game of âcatching up laterâ instead of deploying the early ntervention me asures that are cheaper andmore effective in the long term
DEVELOPMENT AND TURBINE ENGINE PERFORMANCE OF THREE ADVANCED RHENIUM CONTAINING SUPERALLOYS FOR SINGLE CRYSTAL AND DIRECTIONALLY SOUDIFIED BLADES AND VANES
ABSTRACT Turbine inlet temperatures over the next few years will approach 1650°C (3000°F) at maximum power for the latest large commercial turbofan engines, resulting in high fuel efficiency and thrust levels approaching 445 kN (100,000 lbs). High reliability and durability must be intrinsically designed into these turbine engines to meet operating economic targets and ETOPS certification requirement This level of performance has been brought about by a combination of advances in air cooling for turbine blades and vanes, design technology for stresses and airflow, single crystal and directionally solidified casting process improvements and the development and use of rhenium (Re) containing high y' volume fraction nickel-base superalloys with advanced coatings, including full-airfoil ceramic thermal bather coatings. Re additions to cast airfoil superalloys not only improve creep and thermo-mechanical fatigue strength but also environmental properties, including coating performance. Re dramatically slows down diffusion in these alloys at high operating temperatures. A team approach has been used to develop a family of two nickel-base single crystal alloys (CMSX-4. containing 3% Re and CMSX0-10 containing 6% Re) and a directionally solidified, columnar grain nickel-base alloy (CM 186 LC: containing 3% Re) for a variety of turbine engine applications. A range of critical properties of these alloys is reviewed in relation to turbine component engineering performance through engine certification testing and service experience. Industrial turbines are now commencing to use this aero developed turbine technology in both small and large frame units in addition to aero-derivative industrial engines. These applications are demanding with high reliability required for turbine airfoils out to 25,000 hours, with perhaps greater than 50% of the time spent at maximum power. Combined cycle efficiencies of large frame industrial engines is scheduled to reach 60% in the U.S. ATS programme. Application experience to a total 1.3 million engine hours and 28,000 hours individual blade set service for CMSX-4 first stage turbine blades is reviewed for a small frame industrial engine. INTRODUCTION During the last 30 years, turbine inlet temperatures have increased by about 500°C (900°F). About 70% of this increase is due to more efficient design of air cooling for turbine blades and vanes, particularly the advent of serpentine convection an
RAPD and microsatellite transferability studies in selected species of Prosopis (section Algarobia) with emphasis on Prosopis juliflora and P. pallida
Recommended from our members
Scenario choice impacts carbon allocation projection at global warming levels
We show that the distribution of anthropogenic carbon between the atmosphere, land surface, and
ocean differs with the choice of projection scenario even for identical changes in mean global surface tempera-
ture. Warming thresholds occur later in lower-CO2-emissions scenarios and with less carbon in the three main
reservoirs than in higher-CO2-emissions scenarios. At 2 âŠC of warming, the mean carbon allocation differs by up
to 63 PgC between scenarios, which is equivalent to approximately 6 years of the current global total emissions.
At the same warming level, higher-CO2-concentration scenarios have a lower combined ocean and land carbon
allocation fraction of the total carbon compared to lower-CO2-concentration scenarios.
The warming response to CO2, quantified as the equilibrium climate sensitivity, ECS, directly impacts the
global warming level exceedance year and hence the carbon allocation. Low-ECS models have more carbon
than high-ECS models at a given warming level because the warming threshold occurs later, allowing more
emissions to accumulate.
These results are important for carbon budgets and mitigation strategies as they impact how much carbon the
ocean and land surface could absorb at a given warming level. Carbon budgeting will be key to reducing the
impacts of anthropogenic climate change, and these findings could have critical consequences for policies aimed
at reaching net zero
"If we use the strength of diversity among researchers we can only improve the quality and impact of our research": Issues of equality, diversity, inclusion, and transparency in the process of applying for research funding
This paper sets out the recommendations that have emerged from a six-month-long exploration and discussion of the processes that take place before research is submitted for funding: the âpre-awardâ environment. Our work concentrated on how this environment is experienced by researchers at all career stages and from a variety of backgrounds, demographics, and disciplines, as well as by research managers and research support professionals. In the later stages of our exploration, representatives from research funders were also involved in the discussions.
The primary component of this project was an analysis of pre-award activities and processes at UK universities, using information collated from workshops with researchers and research management and support staff. The findings of this analysis were presented as a workflow diagram, which was then used to surface issues relating to equality, diversity, inclusion, and transparency in context. The workflow diagram and the issues highlighted by it were used to structure discussions at a symposium for a range of research stakeholders, held in Bristol, UK, in January 2023. The recommendations set out in this paper are drawn from discussions that took place at that event.
This paper is not an exhaustive landscape analysis, nor a review of existing research and practice in the area of pre-award processes or of recent thinking on the topics of equality, diversity, and inclusion (EDI). Instead, it aims to summarise and encapsulate the suggestions put forward by the stakeholders during the symposium. These recommendations, from experienced professionals working in the field, are based on their encounters with the issues raised in the project. They do not solely relate to those working on pre-award processes, but may also apply to funders, policymakers, university leaders, and professional associations, since many of the challenges flagged in our research are systemic and cultural, and reach far beyond the research office
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint
magnitudes with a fast cadence will enable many of the exciting science
opportunities of the next decade. The Large Synoptic Survey Telescope (LSST)
will have an effective aperture of 6.7 meters and an imaging camera with field
of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over
20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with
fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a
total point-source depth of r~27.5. The LSST Science Book describes the basic
parameters of the LSST hardware, software, and observing plans. The book
discusses educational and outreach opportunities, then goes on to describe a
broad range of science that LSST will revolutionize: mapping the inner and
outer Solar System, stellar populations in the Milky Way and nearby galaxies,
the structure of the Milky Way disk and halo and other objects in the Local
Volume, transient and variable objects both at low and high redshift, and the
properties of normal and active galaxies at low and high redshift. It then
turns to far-field cosmological topics, exploring properties of supernovae to
z~1, strong and weak lensing, the large-scale distribution of galaxies and
baryon oscillations, and how these different probes may be combined to
constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at
http://www.lsst.org/lsst/sciboo
Frequency of extreme Sahelian storms tripled since 1982 in satellite observations
The hydrological cycle is expected to intensify under global
warming, with studies reporting more frequent extreme rain
events in many regions of the world, and predicting increases in future flood frequency. Such early, predominantly mid-latitude observations are essential because of shortcomings within climate models in their depiction of convective rainfall. A globally important group of intense stormsâmesoscale convective systems (MCSs)âposes a particular challenge, because they organize dynamically on spatial scales that cannot be resolved by conventional climate models. Here, we use 35 years of satellite observations from the West African Sahel to reveal a persistent increase in the frequency of the most intense MCSs. Sahelian storms are some of the most powerful on the planet, and rain gauges in this region have recorded a rise in âextremeâ daily rainfall totals. We find that intense MCS frequency is only weakly related to the multidecadal recovery of Sahel annual rainfall, but is highly correlated with global land temperatures. Analysis of trends across Africa reveals that MCS intensification is limited to a narrow band south of the Sahara desert. During this period, wet-season Sahelian temperatures have not risen, ruling out the possibility that rainfall has intensified in response to locally warmer conditions. On the other hand, the meridional temperature gradient spanning the Sahel has increased in recent decades, consistent with anthropogenic forcing driving enhanced Saharan warming. We argue that Saharan warming intensifies convection within Sahelian MCSs through increased wind shear and changes to the Saharan air layer. The meridional gradient is projected to strengthen throughout the twenty-first century, suggesting that the Sahel will experience particularly marked increases in extreme rain. The remarkably rapid intensification of Sahelian MCSs since the 1980s sheds new light on the response of organized tropical convection to global warming, and challenges conventional projections made by general circulation models
- âŠ