Expected Supremum of a Random Linear Combination of Shifted Kernels

We address the expected supremum of a linear combination of shifts of the sinc kernel with random coefficients. When the coefficients are Gaussian, the expected supremum is of order \sqrt{\log n}, where n is the number of shifts. When the coefficients are uniformly bounded, the expected supremum is of order \log\log n. This is a noteworthy difference to orthonormal functions on the unit interval, where the expected supremum is of order \sqrt{n\log n} for all reasonable coefficient statistics.Comment: To appear in the Journal of Fourier Analysis and Application

Typical entanglement of stabilizer states

How entangled is a randomly chosen bipartite stabilizer state? We show that if the number of qubits each party holds is large the state will be close to maximally entangled with probability exponentially close to one. We provide a similar tight characterization of the entanglement present in the maximally mixed state of a randomly chosen stabilizer code. Finally, we show that typically very few GHZ states can be extracted from a random multipartite stabilizer state via local unitary operations. Our main tool is a new concentration inequality which bounds deviations from the mean of random variables which are naturally defined on the Clifford group.Comment: Final version, to appear in PRA. 11 pages, 1 figur

Comparison of Two Cut-to-Length Harvesting Systems Operating in Eastern Hardwoods

We compared production rates, operating costs, and break-even points (BEP) for small and large cut-to-length (CTL) harvesting systems operating at several machine utilization rates (MUR) in mixed hardwood and softwood stands in Vermont. The small CTL harvester produced 11.08 m3 [391.4 ft3] per productive machine hour (PMH) compared to 14.83 m3 [523.80 ft3] per PMH for the large harvester. The impact of average tree size (volume) on cost was substantial but similar for both CTL systems. At a fixed stump-to-landing logging cost of about $14.12/m3 or [$0.40/ft3], the BEP tree size was 0.14 m3 [5.0 ft3] for the small harvester and 0.26 m3 [9.33 ft3] for the large system at the 85 percent MUR. At an MUR of 70 and 85 percent, the processing cost for trees that averaged 0.08 m3 [3.0ft3] was $22.19 and$18.28/m3 [$0.6285 and$0.5176/ft3], respectively, for the small CTL harvester. Results were similar for the large harvester. Either CTL system would be effective in helping managers meet forest management goals in eastern hardwood stands

Modeling and Validating the Grabbing Forces of Hydraulic Log Grapples Used in Forest Operations

The grabbing forces of log grapples were modeled and analyzed mathematically under operating conditions when grabbing logs from compact log piles and from bunch-like log piles. The grabbing forces are closely related to the structural parameters of the grapple, the weight of the grapple, and the weight of the log grabbed. An operational model grapple was designed and tested to validate grabbing forces of the mathematical models while grabbing logs from five alternative diameter classes under two different working conditions. The working conditions and log sizes affected the grabbing forces significantly. Validation results suggest that the mathematical models developed can be used to estimate the grabbing forces required in the design process of log grapples. The results can be used by equipment manufacturers and researchers involved in the engineering design of grapples used in harvesting operations

Simulating Cut-to-Length Harvesting Operations in Appalachian Hardwoods

Cut-to-length (CTL) harvesting systems involving small and large harvesters and a forwarder were simulated using a modular computer simulation model. The two harvesters simulated were a modified John Deere 988 tracked excavator with a single grip sawhead and a Timbco T425 based excavator with a single grip sawhead. The forwarder used in the simulations was a Valmet 524 machine with 2.4-meter log bunks. Production rates and costs were examined for a wide range of even-age oak forest stand conditions. The simulation results suggest that when the tree's DBH is less than 26 cm, harvesting using the Timbco T425 is about 30% more expensive than using the John Deere 988. However, if the tree is larger than 26 cm of DBH, the unit cost of the Timbco T425 was about 8% less than that of the John Deere 988. The balanced John Deere 988 CTL system was 31% more productive and 8% more expensive than the balanced Timbco T425 CTL system in the 20 to 36 cm DBH range. General regression equations were developed for estimating the productivity and cost for the range of conditions simulated. The results should be valuable to managers, planners, and loggers considering the use of CTL systems in this region

A Three-Dimensional Bucking System for Optimal Bucking of Central Appalachian

An optimal tree stem bucking system was developed for central Appalachian hardwood species using three-dimensional (3D) modeling techniques. ActiveX Data Objects were implemented via MS Visual C++/OpenGL to manipulate tree data which were supported by a backend relational data model with five data entity types for stems, grades and prices, logs, defects, and stem shapes. A network analysis algorithm was employed to achieve the optimal bucking solution with four different alternative stage intervals under the bucking by value principle. A total of 264 tree stems were measured in the field including stem dimensions, defects, sweep, and the manual bucking solution of each stem. Results when using the 3D optimal bucking system suggest that compared to manual bucking the total log value and volume gain from each tree stem could be increased on average by 31 to 38 percent and 16 to 17 percent, respectively. Results also show the individual tree stem utilization rate could be increased by 10 to 11 percent. The optimal bucking system developed can be used as a training tool on desktop PCs and can also be installed on field PCs to aid field buckers and operators of sawbucks. The 3D bucking optimization system developed in this research should be valuable to operators in the central Appalachian region due to the variability in tree stems and species of hardwoods

Optical/near-infrared selection of red QSOs: Evidence for steep extinction curves towards galactic centers?

We present the results of a search for red QSOs using a selection based on optical imaging from SDSS and near-infrared imaging from UKIDSS. For a sample of 58 candidates 46 (79%) are confirmed to be QSOs. The QSOs are predominantly dust-reddened except a handul at redshifts z>3.5. The dust is most likely located in the QSO host galaxies. 4 (7%) of the candidates turned out to be late-type stars, and another 4 (7%) are compact galaxies. The remaining 4 objects we could not identify. In terms of their optical spectra the QSOs are similar to the QSOs selected in the FIRST-2MASS red Quasar survey except they are on average fainter, more distant and only two are detected in the FIRST survey. We estimate the amount of extinction using the SDSS QSO template reddened by SMC-like dust. It is possible to get a good match to the observed (restframe ultraviolet) spectra, but for nearly all the reddened QSOs it is not possible to match the near-IR photometry from UKIDSS. The likely reasons are that the SDSS QSO template is too red at optical wavelengths due to contaminating host galaxy light and that the assumed SMC extinction curve is too shallow. Our survey has demonstrated that selection of QSOs based on near-IR photometry is an efficent way to select QSOs, including reddened QSOs, with only small contamination from late-type stars and compact galaxies. This will be useful with ongoing and future wide-field near-IR surveys such as the VISTA and EUCLID surveys. [Abridged]Comment: 74 pages, 6 figures. Accepted for for publication in ApJ

On the sizes of z>2 Damped Lyman-alpha Absorbing Galaxies

Recently, the number of detected galaxy counterparts of z > 2 Damped Lyman-alpha Absorbers in QSO spectra has increased substantially so that we today have a sample of 10 detections. M{\o}ller et al. in 2004 made the prediction, based on a hint of a luminosity-metallicity relation for DLAs, that HI size should increase with increasing metallicity. In this paper we investigate the distribution of impact parameter and metallicity that would result from the correlation between galaxy size and metallicity. We compare our observations with simulated data sets given the relation of size and metallicity. The observed sample presented here supports the metallicity-size prediction: The present sample of DLA galaxies is consistent with the model distribution. Our data also show a strong relation between impact parameter and column density of HI. We furthermore compare the observations with several numerical simulations and demonstrate that the observations support a scenario where the relation between size and metallicity is driven by feedback mechanisms controlling the star-formation efficiency and outflow of enriched gas.Comment: Accepted for publishing in MNRAS lette