2,347 research outputs found
The C-5A active lift distribution control system
The ALDCS development and design tasks, ALDCS functional configuration, and resulting challenges encountered while accomplishing the first phase of the program are described. These tasks are establishing system requirements and criteria and synthesizing a system mechanization to meet the desired load alleviation, stability margins, flight safety, and flying qualities performance. Results of the ALDCS development and prototype system flight simulation programs, and control law optimization including system stability, handling qualities and structural load analyses are presented, along with concluding remarks relative to the system design integration
Water dimer absorption of visible light
International audienceLaboratory measurements of water vapor absorption using cavity ring-down spectroscopy revealed a broad absorption at 405 nm with a quadratic dependence on water monomer concentration, a similar absorption with a linear component at 532 nm, and only linear absorption at 570 nm in the vicinity of water monomer peaks. D2O absorption is weaker and linear at 405 nm. Van't Hoff plots constructed at 405.26 nm suggest that for dimerization, Keq=0.056±0.02 atm?1, ?H°301 K=?16.6±2 kJ mol?1 and ?S°301 K=?80±10 J mol?1 K?1. This transition peaks at 409.5 nm, could be attributed to the 8th overtone of water dimer and the 532 nm absorption to the 6th overtone. It is possible that some lower overtones previously searched for are less enhanced. These absorptions could increase water vapor feed back calculations leading to higher global temperature projections with currently projected greenhouse gas levels or greater cooling from greenhouse gas reductions
Alien Registration- Hargrove, Mary J. (Mars Hill, Aroostook County)
https://digitalmaine.com/alien_docs/33934/thumbnail.jp
Is the even distribution of insecticide-treated cattle essential for tsetse control? Modelling the impact of baits in heterogeneous environments
Background:
Eliminating Rhodesian sleeping sickness, the zoonotic form of Human African Trypanosomiasis, can be achieved only through interventions against the vectors, species of tsetse (Glossina). The use of insecticide-treated cattle is the most cost-effective method of controlling tsetse but its impact might be compromised by the patchy distribution of livestock. A deterministic simulation model was used to analyse the effects of spatial heterogeneities in habitat and baits (insecticide-treated cattle and targets) on the distribution and abundance of tsetse.
Methodology/Principal Findings:
The simulated area comprised an operational block extending 32 km from an area of good habitat from which tsetse might invade. Within the operational block, habitat comprised good areas mixed with poor ones where survival probabilities and population densities were lower. In good habitat, the natural daily mortalities of adults averaged 6.14% for males and 3.07% for females; the population grew 8.46in a year following a 90% reduction in densities of adults and pupae, but expired when the population density of males was reduced to <0.1/km2; daily movement of adults averaged 249 m for males and 367 m for females. Baits were placed throughout the operational area, or patchily to simulate uneven distributions of cattle and targets. Gaps of 2–3 km between baits were inconsequential provided the average imposed mortality per km2 across the entire operational area was maintained. Leaving gaps 5–7 km wide inside an area where baits killed 10% per day delayed effective control by 4–11 years. Corrective measures that put a few baits within the gaps were more effective than deploying extra baits on the edges.
Conclusions/Significance:
The uneven distribution of cattle within settled areas is unlikely to compromise the impact of insecticide-treated cattle on tsetse. However, where areas of >3 km wide are cattle-free then insecticide-treated targets should be deployed to compensate for the lack of cattle
Position Sensing from Charge Dispersion in Micro-Pattern Gas Detectors with a Resistive Anode
Micro-pattern gas detectors, such as the Gas Electron Multiplier (GEM) and
the Micromegas need narrow high density anode readout elements to achieve good
spatial resolution. A high-density anode readout would require an unmanageable
number of electronics channels for certain potential micro-detector
applications such as the Time Projection Chamber. We describe below a new
technique to achieve good spatial resolution without increasing the electronics
channel count in a modified micro-detector outfitted with a high surface
resistivity anode readout structure. The concept and preliminary measurements
of spatial resolution from charge dispersion in a modified GEM detector with a
resistive anode are described below.Comment: 14 pages, 8 figures, submitted to Nucl. Inst. Meth; typo in eqn 4
corrected, fig 2 updated accordingl
Mechatronics Education at Kettering University: Development of Learning- Specific Hardware and Software
A series of learning-specific electronic circuit boards and associated software has been developed to support mechatronics education in the Mechanical Engineering Department at Kettering University. The boards are designed to interface to the Toshiba TLCS-900H Microprocessor Trainer and Evaluation Board. The purpose of these boards is to provide mechanical engineering students of mechatronics with robust hardware that readily permits interfacing of sensors and actuators to microcontrollers used in mechatronic applications. Further, the boards feature signal conditioning circuits for use in conjunction with sensors, and driver circuits for operating high-current actuating devices. Supporting software has been written to permit ready use of the features of the hardware with only a functional knowledge of electronics, thus helping mechanical engineering students realize the full potential of mechatronics applications in an introductory course. Additionally, a stand-alone microprocessor board with flash memory has been designed and fabricated to permit students move out of the development laboratory and readily embed the electronics portion of a mechatronics device into their projects
Spatial resolution of a GEM readout TPC using the charge dispersion signal
A large volume Time Projection Chamber (TPC) is being considered for the
central charged particle tracker for the detector for the proposed
International Linear Collider (ILC). To meet the ILC-TPC spatial resolution
challenge of ~100 microns with a manageable number of readout pads and channels
of electronics, Micro Pattern Gas Detectors (MPGD) are being developed which
could use pads comparable in width to the proportional-wire/cathode-pad TPC. We
have built a prototype GEM readout TPC with 2 mm x 6 mm pads using the new
concept of charge dispersion in MPGDs with a resistive anode. The dependence of
transverse resolution on the drift distance has been measured for small angle
tracks in cosmic ray tests without a magnetic field for Ar/CO2 (90:10). The
GEM-TPC resolution with charge dispersion readout is significantly better than
previous measurements carried out with conventional direct charge readout
techniques.Comment: 5 figures, 10 page
Recommended from our members
UPC++ v1.0 Programmer’s Guide, Revision 2020.3.0
UPC++ is a C++11 library that provides Partitioned Global Address Space (PGAS) programming. It is designed for writing parallel programs that run efficiently and scale well on distributed-memory parallel computers. The PGAS model is single program, multiple-data (SPMD), with each separate constituent process having access to local memory as it would in C++. However, PGAS also provides access to a global address space, which is allocated in shared segments that are distributed over the processes. UPC++ provides numerous methods for accessing and using global memory. In UPC++, all operations that access remote memory are explicit, which encourages programmers to be aware of the cost of communication and data movement. Moreover, all remote-memory access operations are by default asynchronous, to enable programmers to write code that scales well even on hundreds of thousands of cores
Resolution studies of cosmic-ray tracks in a TPC with GEM readout
A large volume TPC is a leading candidate for the central tracking detector
at a future high energy linear collider. To improve the resolution a new
readout based on micro-pattern gas detectors is being developed. Measurements
of the spatial resolution of cosmic-ray tracks in a GEM TPC are presented. We
find that the resolution suffers if the readout pads are too wide with respect
to the charge distribution at the readout plane due to insufficient charge
sharing. For narrow pads of 2 x 6 mm**2 we measure a resolution of 100
micometer at short drift distances in the absence of an axial magnetic field.
The dependence of the spatial resolution as a function of drift distance allows
the determination of the underlying electron statistics. Our results show that
the present technique uses about half the statistical power available from the
number of primary electrons. The track angle effect is observed as expected.Comment: 18 pages, 8 figures, version as published in Nucl. Inst. Met
Use of Current 2010 Forest Disturbance Monitoring Products for the Conterminous United States in Aiding a National Forest Threat Early Warning System
This presentation discusses contributions of near real time (NRT) MODIS forest disturbance detection products for the conterminous United States to an emerging national forest threat early warning system (EWS). The latter is being developed by the USDA Forest Service s Eastern and Western Environmental Threat Centers with help from NASA Stennis Space Center and the Oak Ridge National Laboratory. Building off work done in 2009, this national and regional forest disturbance detection and viewing capability of the EWS employs NRT MODIS NDVI data from the USGS eMODIS group and historical NDVI data from standard MOD13 products. Disturbance detection products are being computed for 24 day composites that are refreshed every 8 days. Products for 2010 include 42 dates of the 24 day composites. For each compositing date, we computed % change in forest maximum NDVI products for 2010 with respect to each of three historical baselines of 2009, 2007-2009, and 2003-2009,. The three baselines enable one to view potential current, recent, and longer term forest disturbances. A rainbow color table was applied to each forest change product so that potential disturbances (NDVI drops) were identified in hot color tones and growth (NDVI gains) in cold color tones. Example products were provided to end-users responsible for forest health monitoring at the Federal and State levels. Large patches of potential forest disturbances were validated based on comparisons with available reference data, including Landsat and field survey data. Products were posted on two internet mapping systems for US Forest Service internal and collaborator use. MODIS forest disturbance detection products were computed and posted for use in as little as 1 day after the last input date of the compositing period. Such products were useful for aiding aerial disturbance detection surveys and for assessing disturbance persistence on both inter- and intra-annual scales. Multiple 2010 forest disturbance events were detected across the nation, including damage from ice storms, tornadoes, caterpillars, bark beetles, and wildfires. This effort enabled improved NRT forest disturbance monitoring capabilities for this nation-wide forest threat EWS
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