10,046 research outputs found
Evidence for new unidentified TeV gamma-ray sources from angularly-correlated hot-spots observed by independent TeV gamma-ray sky surveys
We have examined the directional cross-correlation of statistical `hot-spots'
between a Northern Sky TeV Gamma Ray Survey by the Milagro Observatory and a
similar survey by the Tibet Array. We find the directions of these hot-spots
are angularly uncorrelated between the two surveys for large angular
separations (Delta theta > 4 degrees), but there appears to be a statistically
significant correlation between hot-spot directions for Delta theta < 1.5
degrees. Independent simulations indicate the chance probability for the
occurrence of this correlation is approximately 10^-4, implying the existence
of one or more previously unobserved TeV gamma-ray sources in these directions.
The data sets are consistent with both point-like sources or diffuse sources
with extent of 1 - 2 degrees.Comment: 12 pages, 2 figures, 3 tables. Submitted to Astrophysical Journal
Letter
The challenge of integrating non-continuous processes-milk powder plant case study
The integration of non-continuous processes such as a milk powder plant present a challenge for existing process integration techniques. Current techniques are generally based on steady and continuous operation which for some industries is not the case. Milk production varies considerably during the year as dairy cows in New Zealand are grazed on pasture, which affects the scheduling and operation of plants on site. The frequency and duration of cleaning cycles and non-productive operating states can have a major affect on energy demand and the availability of heat sources and heat sinks. In this paper the potential for indirect heat transfer between the several plants using a heat recovery loop and stratified tank at a typical New Zealand dairy factory is investigated. The maximum amount of heat recovery is calculated for a range of recirculation loop temperatures. The maximum amount of heat recovery can be increased considerably if the temperature of the hot fluid in the recirculation loop is varied depending on which condition the site is operating under
Integrating heat recovery from milk powder spray dryer exhausts in the dairy industry
Heat recovery from milk powder spray dryer exhausts has proven challenging due to both economic and thermodynamic constraints. Integrating the dryer with the rest of the process (e.g. evaporation stages) can increase the viability of exhaust recovery. Several potential integration schemes for a milk powder plant have been investigated. Indirect heat transfer via a coupled loop between the spray dryer exhaust and various heat sinks were modeled and the practical heat recovery potential determined. Hot utility use was reduced by as much as 21% if suitable heat sinks are selected. Due to high particle loading and operating temperatures in the particle sticky regime, powder deposition in the exhaust heat exchanger is perhaps the greatest obstacle for implementing heat recovery schemes on spray dryers. Adequate cleaning systems are needed to ensure continuous dyer operation
An optimal controller based on linear approximation of an acoustical test facility, part B Final report
Optimal digital controller based on linear approximation of acoustical test facility, for determining effects of supersonic rocket engine noise on vehicle surfac
Random polarization dynamics in a resonant optical medium
Random optical-pulse polarization switching along an active optical medium in
the -configuration with spatially disordered occupation numbers of its
lower energy sub-level pair is described using the idealized integrable
Maxwell-Bloch model. Analytical results describing the light
polarization-switching statistics for the single self-induced transparency
pulse are compared with statistics obtained from direct Monte-Carlo numerical
simulations.Comment: 7 pages, 3 figure
Highly-tunable formation of nitrogen-vacancy centers via ion implantation
We demonstrate highly-tunable formation of nitrogen-vacancy (NV) centers
using 20 keV 15N+ ion implantation through arrays of high-resolution apertures
fabricated with electron beam lithography. By varying the aperture diameters
from 80 to 240 nm, as well as the average ion fluences from 5 x 10^10 to 2 x
10^11 ions/cm^2, we can control the number of ions per aperture. We analyze the
photoluminescence on multiple sites with different implantation parameters and
obtain ion-to-NV conversion yields of 6 to 7%, consistent across all ion
fluences. The implanted NV centers have spin dephasing times T2* ~ 3
microseconds, comparable to naturally occurring NV centers in high purity
diamond with natural abundance 13C. With this technique, we can
deterministically control the population distribution of NV centers in each
aperture, allowing for the study of single or coupled NV centers and their
integration into photonic structures.Comment: Related papers at http://pettagroup.princeton.ed
Customary International Humanitarian Law and Multinational Military Operations in Malaysia
The International Committee of the Red Cross published a study in 2005 identifying rules of customary international law applicable to armed conflict and theoretically binding on all nations. This study found that customary state practice has come to encompass and in some cases exceed protections contained in the Additional Protocols of 1977 to the Geneva Conventions of 1949, regardless of their applicability to a given conflict. These findings may impact the domestic law enforcement practices of states not parties to Additional Protocol II, which regulates non-international armed conflict. Furthermore, the study may have indirect effects on military cooperation and legal reform worldwide. By strengthening the legal criticism of domestic laws not compliant with international humanitarian law, the study directly challenges non-party states seeking to obtain unqualified military assistance during internal conflicts. However, this same effect will lend support to increased observance of international humanitarian law as intervening statesâ militaries apply pressure to realize compliance with customary international law. This comment identifies these implications by considering a hypothetical future counter-insurgency in Malaysia in which the United States offers military assistance to the Malaysian government
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