623 research outputs found
Dynamics of short pressure probes
Report presents practical information for incorporating particle impact protection features and average total pressure measurement into probe design while optimizing probe transient response. Computer program calculates probe response, based on Bergh-Tijdeman equation
Mapping the neutral atomic hydrogen gas outflow in the restarted radio galaxy 3C 236
The energetic feedback that is generated by radio jets in active galactic
nuclei (AGNs) has been suggested to be able to produce fast outflows of atomic
hydrogen (HI) gas that can be studied in absorption at high spatial resolution.
We have used the Very Large Array (VLA) and a global
very-long-baseline-interferometry (VLBI) array to locate and study in detail
the HI outflow discovered with the Westerbork Synthesis Radio Telescope (WSRT)
in the re-started radio galaxy 3C 236. We confirm, from the VLA data, the
presence of a blue-shifted wing of the HI with a width of
. This HI outflow is partially recovered by the
VLBI observation. In particular, we detect four clouds with masses of
with VLBI that do not follow the regular
rotation of most of the HI. Three of these clouds are located, in projection,
against the nuclear region on scales of , while the
fourth is co-spatial to the south-east lobe at a projected distance of
. Their velocities are between and
blue-shifted with respect to the velocity of the
disk-related HI. These findings suggest that the outflow is at least partly
formed by clouds, as predicted by some numerical simulations and originates
already in the inner (few tens of pc) region of the radio galaxy. Our results
indicate that all of the outflow could consist of many clouds with perhaps
comparable properties as the ones detected, distributed also at larger radii
from the nucleus where the lower brightness of the lobe does not allow us to
detect them. However, we cannot rule out the presence of a diffuse component of
the outflow. The fact that 3C 236 is a low excitation radio galaxy, makes it
less likely that the optical AGN is able to produce strong radiative winds
leaving the radio jet as the main driver for the HI outflow.Comment: 13 pages, 5 figures, accepted for publication in Astronomy &
Astrophysic
Operating experience with four 200 kW Mod-0A wind turbine generators
The windpowered generator, Mod-0A, and its advantages and disadvantages, particularly as it affects reliability, are discussed. The machine performance with regard to power availability and power output is discussed
Методичні вказівки до лабораторних занять з дисципліни "Теорія керування"
Метою виконання лабораторних робіт є побудова законів керування для лінійних динамічних систем з урахуванням заданих вимог керування. Моделювання лінійних динамічних систем у контурі керування є необхід-ним етапом розв’язання різноманітних завдань аналізу і синтезу систем керування
Astrophysical Supercomputing with GPUs: Critical Decisions for Early Adopters
General purpose computing on graphics processing units (GPGPU) is
dramatically changing the landscape of high performance computing in astronomy.
In this paper, we identify and investigate several key decision areas, with a
goal of simplyfing the early adoption of GPGPU in astronomy. We consider the
merits of OpenCL as an open standard in order to reduce risks associated with
coding in a native, vendor-specific programming environment, and present a GPU
programming philosophy based on using brute force solutions. We assert that
effective use of new GPU-based supercomputing facilities will require a change
in approach from astronomers. This will likely include improved programming
training, an increased need for software development best-practice through the
use of profiling and related optimisation tools, and a greater reliance on
third-party code libraries. As with any new technology, those willing to take
the risks, and make the investment of time and effort to become early adopters
of GPGPU in astronomy, stand to reap great benefits.Comment: 13 pages, 5 figures, accepted for publication in PAS
Tool-free, Cosmetically Hidden Phone Display and Back Cover Disassembly Port
The back cover and/or display displays of many portable devices such as smartphones and tablets are often integrated with the main assembly. If the back cover assembly or the phone display needs to be removed (e.g., to access the battery) or needs to be replaced, the device owner needs to approach a service center for such work since specialized tools are often required for removal. This disclosure describes a mechanism for easy removal of back cover or display of a device without impacting aesthetics of the device. Per the techniques of this disclosure, a slot is machined or molded on the adhesive landing between the display/ back cover and the SIM tray opening. The slot can be accessed easily with the SIM tray tool or a paperclip
INTERSPECIFIC AND INTRASPECIFIC COMPETITION OF COMMON SUNFLOWER (HELIANTHUS ANNUUS L.) IN FIELD CORN (ZEA MAYS L.)
Common sunflower is a competitive annual native dicot found in disturbed areas, on roadsides, dry prairies, and in row crops. Common sunflower is a competitive weed, but little data exist on interference, economic impacts, and competition in field corn. Field studies were conducted in 2006 and 2007 to 1) define the density-dependent effects of common sunflower competition with corn; 2) define the necessary weed-free periods of common sunflower in corn; 3) evaluate common sunflower control with herbicides; 4) and define the economic impact of common sunflower interference with corn.
Corn grain yield was significantly reduced when common sunflower densities reached 1 plant/m of row and potentitially damaging common sunflower densities occurred if allowed to compete for more than 2 to 4 wk after planting for maximum corn yield. No significant corn yield reduction occurred if common sunflowers emerged 8 wk after planting. Growing degree day (GDD) heat units for corn showed that the critical point for control of common sunflower was approximately 300 GDD. Atrazine applied PRE, atrazine followed by (fb) glyphosate or halosulfuron POST, glyphosate POST, halosulfuron POST, and halosulfuron plus nicosulfuron POST controlled >87% of common sunflower. Atrazine applied PRE in a 30-cm band, nicosulfuron POST, and atrazine broadcast plus S-metolachlor PRE showed significantly lower common sunflower control and corn grain yield, when compared to atrazine PRE fb glyphosate POST.
Economic impact of one sunflower/6 m of crop row caused a yield loss of 293 kg/ha. Various corn planting densities showed that corn yield can be reduced 1990 kg/ha with common sunflower competition. Corn planting densities of 49400 and 59300 plants/ha provided the greatest net returns with or without the presence of common sunflower competition. The highest net returns occurred with no common sunflower competition in 2006 and 2007, at 2,687/ha, respectively, when net corn prices were 6.00/bu). Potential control costs of various herbicide treatments revealed net returns of 1,910/ha in 2006 and 1,943/ha in 2007. Determining the economic impact of common sunflower interference in field corn allows producers to estimate the overall net return based upon density and duration of common sunflower interference, while considering varying net corn prices, crop planting density, and herbicide application costs
Design and Synthesis of Novel Quinone Inhibitors Targeted to the Redox Function of Apurinic/Apyrimidinic Endonuclease 1/Redox Enhancing Factor-1 (Ape1/Ref-1)
The multifunctional enzyme apurinic endonuclease 1/redox enhancing factor 1 (Ape1/ref-1) maintains genetic fidelity through the repair of apurinic sites and regulates transcription through redox-dependent activation of transcription factors. Ape1 can therefore serve as a therapeutic target in either a DNA repair or transcriptional context. Inhibitors of the redox function can be used as either therapeutics or novel tools for separating the two functions for in vitro study. Presently there exist only a few compounds that have been reported to inhibit Ape1 redox activity; here we describe a series of quinones that exhibit micromolar inhibition of the redox function of Ape1. Benzoquinone and naphthoquinone analogues of the Ape1-inhibitor E3330 were designed and synthesized to explore structural effects on redox function and inhibition of cell growth. Most of the naphthoquinones were low micromolar inhibitors of Ape1 redox activity, and the most potent analogues inhibited tumor cell growth with IC50 values in the 10−20 μM range
GPUVerify: A Verifier for GPU Kernels
We present a technique for verifying race- and divergence-freedom of GPU kernels that are written in mainstream ker-nel programming languages such as OpenCL and CUDA. Our approach is founded on a novel formal operational se-mantics for GPU programming termed synchronous, delayed visibility (SDV) semantics. The SDV semantics provides a precise definition of barrier divergence in GPU kernels and allows kernel verification to be reduced to analysis of a sequential program, thereby completely avoiding the need to reason about thread interleavings, and allowing existing modular techniques for program verification to be leveraged. We describe an efficient encoding for data race detection and propose a method for automatically inferring loop invari-ants required for verification. We have implemented these techniques as a practical verification tool, GPUVerify, which can be applied directly to OpenCL and CUDA source code. We evaluate GPUVerify with respect to a set of 163 kernels drawn from public and commercial sources. Our evaluation demonstrates that GPUVerify is capable of efficient, auto-matic verification of a large number of real-world kernels
Sugar maple (Acer saccharum March.) growth is influenced by close conspecifics and skid trait proximity following selection harvest
In this study, we quantified the effects of local neighbourhood competition, light availability, and proximity to skid trails on the growth of sugar maple (Acer saccharum Marsh.) trees following selection harvest. We hypothesized that growth would increase with decreasing competition and increasing light availability, but that proximity to skid trails would negatively affect growth. A total of 300 sugar maples were sampled 10 years after selection harvesting in 18 stands in Témiscamingue (Québec, Canada). Detailed tree and skid trail maps were obtained in one 0.4 ha plot per stand. Square-root transformed radial growth data were fitted to a linear mixed model that included tree diameter, crown position, a neighbourhood competition index, light availability (estimated using the SORTIE light model), and distance to the nearest skid trail as explanatory variables. We considered various distance-dependent or -independent indices based on neighbourhood radii ranging from 6 to 12 m. The competition index that provided the best fit to the data was a distance-dependent index computed in a 6 m search radius, but a\ud
distance-independent version of the competition index provided an almost equivalent fit to data. Models corresponding to all combinations of main effects were fit to data using maximum likelihood, and weighted averages of parameter estimates were obtained usingmultimodel inference. All predictors had\ud
an influence on growth, with the exception of light. Radial growth decreased with increasing tree diameter, level of competition and proximity to skid trails, and varied among crown positions with trees in suppressed and intermediate positions having lower growth rates than codominants and dominants. Our results indicate that in selection managed stands, the radial growth of sugarmaple trees depends on\ud
competition from close (6 m) conspecific neighbours, and is still affected by proximity to skid trails 10 years after harvesting. Such results underscore the importance of minimizing the extent of skid trail networks by careful pre-harvest planning of trail layout. We also conclude that the impact of heterogeneity among individual-tree neighbourhoods, such as those resulting from alternative spatial patterns of harvest, can usefully be integrated into models of post-harvest tree growth
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