Evolutionary sensor allocation for the Space Surveillance Network

2017 ◽  
Vol 15 (3) ◽  
pp. 303-322 ◽  
Author(s):  
Gabriel H Greve ◽  
Kenneth M Hopkinson ◽  
Gary B Lamont
Keyword(s):  
Solution Space ◽  
Current Method ◽  
Field Of View ◽  
Evolutionary Strategy ◽  
Small Scale ◽  
Relative Priority ◽  
Surveillance Network ◽  
Object Locations ◽  
Importance Factor ◽  
Single Objective

The congested exosphere continues to contain more satellites and debris, raising the potential for destructive collisions. The Special Perturbations (SP) Tasker algorithm currently assigns the ground sensors tasks to track object locations. Accurate locations help avoid collisions. However, the SP Tasker ignores priority, which is the satellite’s importance factor. This article introduces the Evolutionary Algorithm Tasker (EAT) to solve the Satellite Sensor Allocation Problem (SSAP), which is a hybrid Evolutionary Strategy and Genetic Algorithm concept including specific techniques to explore the solution space and exploit the best solutions found. This approach goes beyond the current method, which does not include priority and other methods from the literature that have been applied to small-scale simulations. The SSAP model implementation extends Multi-Objective Evolutionary Algorithms (MOEAs) from the literature while accounting for priorities. Multiple real-world factors are considered, including each sensor’s field-of-view, the orbital opportunities to track a satellite, the capacity of the sensor, and the relative priority of the satellites. The single objective EAT is statistically compared to the SP Tasker algorithm. Simulations show that both the EAT and MOEA approaches effectively use priority in the core tasking algorithms to ensure that higher priority satellites are tracked.

scholarly journals Movement Around Real and Virtual Cluttered Environments

2005 ◽  
Vol 14 (5) ◽  
pp. 580-596 ◽  
Author(s):  
Simon Lessels ◽  
Roy A. Ruddle
Keyword(s):  
Real World ◽  
Search Task ◽  
Scale Space ◽  
Visual Scene ◽  
Field Of View ◽  
Small Scale ◽  
High Fidelity ◽  
Cluttered Environments ◽  
The Real ◽  
Desktop Virtual Environment

Two experiments investigated participants' ability to search for targets in a cluttered small-scale space. The first experiment was conducted in the real world with two field of view conditions (full vs. restricted), and participants found the task trivial to perform in both. The second experiment used the same search task but was conducted in a desktop virtual environment (VE), and investigated two movement interfaces and two visual scene conditions. Participants restricted to forward only movement performed the search task quicker and more efficiently (visiting fewer targets) than those who used an interface that allowed more flexible movement (forward, backward, left, right, and diagonal). Also, participants using a high fidelity visual scene performed the task significantly quicker and more efficiently than those who used a low fidelity scene. The performance differences among all the conditions decreased with practice, but the performance of the best VE group approached that of the real-world participants. These results indicate the importance of using high fidelity scenes in VEs, and suggest that the use of a simple control system is sufficient for maintaining one's spatial orientation during searching.

Space Contraction and Partition Algorithm for Combinatorial Optimization

2011 ◽  
Vol 421 ◽  
pp. 559-563
Author(s):  
Yong Chao Gao ◽  
Li Mei Liu ◽  
Heng Qian ◽  
Ding Wang
Keyword(s):  
Combinatorial Optimization ◽  
Optimization Problem ◽  
Optimization Problems ◽  
Solution Space ◽  
Search Space ◽  
Small Scale ◽  
Optimal Solutions ◽  
Solution Quality ◽  
Intelligent Algorithms ◽  
Combinatorial Optimization Problems

The scale and complexity of search space are important factors deciding the solving difficulty of an optimization problem. The information of solution space may lead searching to optimal solutions. Based on this, an algorithm for combinatorial optimization is proposed. This algorithm makes use of the good solutions found by intelligent algorithms, contracts the search space and partitions it into one or several optimal regions by backbones of combinatorial optimization solutions. And optimization of small-scale problems is carried out in optimal regions. Statistical analysis is not necessary before or through the solving process in this algorithm, and solution information is used to estimate the landscape of search space, which enhances the speed of solving and solution quality. The algorithm breaks a new path for solving combinatorial optimization problems, and the results of experiments also testify its efficiency.

scholarly journals A wide field-of-view imaging DOAS instrument for two-dimensional trace gas mapping from aircraft

2015 ◽  
Vol 8 (12) ◽  
pp. 5113-5131 ◽  
Author(s):  
A. Schönhardt ◽  
P. Altube ◽  
K. Gerilowski ◽  
S. Krautwurst ◽  
J. Hartmann ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Point Sources ◽  
West Germany ◽  
Field Of View ◽  
Trace Gas ◽  
Optical Absorption Spectroscopy ◽  
Small Scale ◽  
Wide Field ◽  
Flight Altitude ◽  
Good Imaging

Abstract. The Airborne imaging differential optical absorption spectroscopy (DOAS) instrument for Measurements of Atmospheric Pollution (AirMAP) has been developed for the purpose of trace gas measurements and pollution mapping. The instrument has been characterized and successfully operated from aircraft. Nitrogen dioxide (NO2) columns were retrieved from the AirMAP observations. A major benefit of the push-broom imaging instrument is the spatially continuous, gap-free measurement sequence independent of flight altitude, a valuable characteristic for mapping purposes. This is made possible by the use of a charge coupled device (CCD) frame-transfer detector. A broad field of view across track of around 48° is achieved with wide-angle entrance optics. This leads to a swath width of about the same size as the flight altitude. The use of fibre coupled light intake optics with sorted light fibres allows flexible instrument positioning within the aircraft and retains the very good imaging capabilities. The measurements yield ground spatial resolutions below 100 m depending on flight altitude. The number of viewing directions is chosen from a maximum of 35 individual viewing directions (lines of sight, LOS) represented by 35 individual fibres. The selection is adapted to each situation by averaging according to signal-to-noise or spatial resolution requirements. Observations at 30 m spatial resolution are obtained when flying at 1000 m altitude and making use of all 35 viewing directions. This makes the instrument a suitable tool for mapping trace gas point sources and small-scale variability. The position and aircraft attitude are taken into account for accurate spatial mapping using the Attitude and Heading Reference System of the aircraft. A first demonstration mission using AirMAP was undertaken in June 2011. AirMAP was operated on the AWI Polar-5 aircraft in the framework of the AIRMETH-2011 campaign. During a flight above a medium-sized coal-fired power plant in north-west Germany, AirMAP clearly detected the emission plume downwind from the exhaust stack, with NO2 vertical columns around 2 × 1016 molecules cm−2 in the plume centre. NOx emissions estimated from the AirMAP observations are consistent with reports in the European Pollutant Release and Transfer Register. Strong spatial gradients and variability in NO2 amounts across and along flight direction are observed, and small-scale enhancements of NO2 above a motorway are detected.

State of the art single-objective optimization of small scale cylindrical cavity receiver

2019 ◽  
Vol 35 ◽  
pp. 278-290 ◽  
Author(s):  
Ahmed M. Daabo ◽  
Yaser S. Al-Mola ◽  
Ammar Y. Al-Rawy ◽  
T. Lattimore
Keyword(s):  
Cylindrical Cavity ◽  
State Of The Art ◽  
Small Scale ◽  
Single Objective

Burn Chamber Test of Ex Situ Thermal Impulse Sensors

2020 ◽  
Vol 74 (5) ◽  
pp. 515-524
Author(s):  
Benjamin R. Anderson ◽  
Natalie Gese ◽  
Ray Gunawidjaja ◽  
Hergen Eilers
Keyword(s):  
Research Laboratory ◽  
Large Scale ◽  
Current Method ◽  
Ex Situ ◽  
Small Scale ◽  
Average Temperature ◽  
Current Test ◽  
Oxide Precursor ◽  
The Us ◽  
Lab Test

Recently, we reported on a novel ex situ thermal impulse sensing technique (based on lanthanide-doped oxide precursor nanoparticles) for use in structural fire forensics and demonstrated its functionality in small-scale lab-based tests. As a next step we have now performed a large-scale lab test at the US Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) Fire Research Laboratory using a burn chamber with three sand burners. In this test we demonstrate our technique’s ability to determine the average temperature experienced by surfaces during the fire. While we successfully demonstrate our techniques accuracy, we also discover several previously unknown vulnerabilities. Namely, we find that: (1) our current method of embedding sensors in paint results in our sensor particles being difficult to recover (due to a large quantity of debris), (2) the current test panels have poor survivability, (3) debris from the fire tests interferes with excitation of dopant Dy ions (limiting our sensors’ functionality), and (4) dispersal in paint results in suppression of the (metastable)tetragonal-to-monoclinic phase transition of ZrO2. To overcome these vulnerabilities we are evaluating new panel materials, paints, and lanthanide-dopants.

scholarly journals Seasonal and intra-diurnal variability of small-scale gravity waves in OH airglow at two Alpine stations

2019 ◽  
Vol 12 (1) ◽  
pp. 457-469 ◽  
Author(s):  
Patrick Hannawald ◽  
Carsten Schmidt ◽  
René Sedlak ◽  
Sabine Wüst ◽  
Michael Bittner
Keyword(s):  
Gravity Waves ◽  
High Frequency ◽  
Phase Speed ◽  
Propagation Direction ◽  
Field Of View ◽  
Small Scale ◽  
Data Sets ◽  
Data Set ◽  
Diurnal Variability ◽  
Fully Automatic

Abstract. Between December 2013 and August 2017 the instrument FAIM (Fast Airglow IMager) observed the OH airglow emission at two Alpine stations. A year of measurements was performed at Oberpfaffenhofen, Germany (48.09∘ N, 11.28∘ E) and 2 years at Sonnblick, Austria (47.05∘ N, 12.96∘ E). Both stations are part of the network for the detection of mesospheric change (NDMC). The temporal resolution is two frames per second and the field-of-view is 55 km × 60 km and 75 km × 90 km at the OH layer altitude of 87 km with a spatial resolution of 200 and 280 m per pixel, respectively. This resulted in two dense data sets allowing precise derivation of horizontal gravity wave parameters. The analysis is based on a two-dimensional fast Fourier transform with fully automatic peak extraction. By combining the information of consecutive images, time-dependent parameters such as the horizontal phase speed are extracted. The instrument is mainly sensitive to high-frequency small- and medium-scale gravity waves. A clear seasonal dependency concerning the meridional propagation direction is found for these waves in summer in the direction to the summer pole. The zonal direction of propagation is eastwards in summer and westwards in winter. Investigations of the data set revealed an intra-diurnal variability, which may be related to tides. The observed horizontal phase speed and the number of wave events per observation hour are higher in summer than in winter.

scholarly journals High-Resolution, Large Field-of-View, and Multi-View Single Objective Light-Sheet Microscopy

2020 ◽  
Author(s):  
Bin Yang ◽  
Alfred Millett-Sikking ◽  
Merlin Lange ◽  
Ahmet Can Solak ◽  
Hirofumi Kobayashi ◽  
...  
Keyword(s):  
High Resolution ◽  
Light Sheet ◽  
Field Of View ◽  
Large Field ◽  
Sample Rotation ◽  
Light Sheet Microscopy ◽  
Spatio Temporal ◽  
Large Living ◽  
Single Objective ◽  
Imaging Speed

Light-sheet microscopy has become the preferred method for long-term imaging of large living samples because of its low photo-invasiveness and good optical sectioning capabilities. Unfortunately, refraction and scattering often pose obstacles to light-sheet propagation and limit imaging depth. This is typically addressed by imaging multiple complementary views to obtain high and uniform image quality throughout the sample. However, multi-view imaging often requires complex multi-objective configurations that complicate sample mounting, or sample rotation that decreases imaging speed. Recent developments in single-objective light-sheet microscopy have shown that it is possible to achieve high spatio-temporal resolution with a single objective for both illumination and detection. Here we describe a single-objective light-sheet microscope that achieves: (i) high-resolution and large field-of-view imaging via a custom remote focusing objective; (ii) simpler design and ergonomics by remote placement of coverslips; (iii) fast volumetric imaging by means of light-sheet stabilised stage scanning – a novel scanning modality that extends the imaging volume without compromising imaging speed nor quality; (iv) multi-view imaging by means of dual orthogonal light-sheet illumination. Finally, we demonstrate the speed, field of view and resolution of our novel instrument by imaging zebrafish tail development.

scholarly journals Using verified citizen science as a tool for monitoring the European hornet (Vespa crabro) in the island of Sardinia (Italy)

NeoBiota ◽  
2019 ◽  
Vol 50 ◽  
pp. 97-108 ◽  
Author(s):  
Michelina Pusceddu ◽  
Ignazio Floris ◽  
Roberto Mannu ◽  
Arturo Cocco ◽  
Alberto Satta
Keyword(s):  
Alien Species ◽  
Citizen Science ◽  
Distribution Area ◽  
Small Scale ◽  
Generalist Predator ◽  
Surveillance Network ◽  
Vespa Crabro ◽  
Gender Education ◽  
North Eastern ◽  
Job Category

The European hornet, Vespa crabro L. (Hymenoptera: Vespidae), is a eusocial insect native to Eurasia that was accidentally introduced in the island of Sardinia (Italy) in 2010. This alien generalist predator could impact on native insect species through predation or competition by modifying interspecific relations in sensitive island ecosystems. As part of the Interreg project ALIEM, the present work regarded the first monitoring activity of the European hornet conducted in Sardinia by means of verified citizen science. The main goals of this study were to define the distribution area of the wasp in 2018 and evaluate the profile and the performance of citizen scientists. Our results showed that V. crabro is mainly located in north-eastern Sardinia and that the hotspot was probably the commercial port of Olbia. Furthermore, data provided by contributors were very accurate and none of the parameters considered to define the participants (age, gender, education level, job category) was a true predictor of a volunteer’s ability to recognise the wasp. In conclusion, this small-scale study suggests that citizen scientists could be a valuable aid to monitor already-established alien species and could be part of a surveillance network for early detection of other potentially invasive alien species not yet introduced in Sardinia, such as the yellow-legged hornet, Vespa velutina, which is already present in northern Italy.

scholarly journals Small-scale physical and chemical structure of diffuse and translucent molecular clouds along the line of sight to Sgr B2

2019 ◽  
Vol 623 ◽  
pp. A68 ◽  
Author(s):  
V. Thiel ◽  
A. Belloche ◽  
K. M. Menten ◽  
A. Giannetti ◽  
H. Wiesemeyer ◽  
...  
Keyword(s):  
Molecular Clouds ◽  
Velocity Structure ◽  
Angular Resolution ◽  
Principal Component ◽  
High Sensitivity ◽  
Field Of View ◽  
Continuum Emission ◽  
Line Of Sight ◽  
Small Scale ◽  
Galactic Centre

Context. The diffuse and translucent molecular clouds traced in absorption along the line of sight to strong background sources have so far been investigated mainly in the spectral domain because of limited angular resolution or small sizes of the background sources. Aims. We aim to resolve and investigate the spatial structure of molecular clouds traced by several molecules detected in absorption along the line of sight to Sgr B2(N). Methods. We have used spectral line data from the EMoCA survey performed with the Atacama Large Millimeter/submillimeter Array (ALMA), taking advantage of its high sensitivity and angular resolution. The velocity structure across the field of view is investigated by automatically fitting synthetic spectra to the detected absorption features, which allows us to decompose them into individual clouds located in the Galactic centre (GC) region and in spiral arms along the line of sight. We compute opacity maps for all detected molecules. We investigated the spatial and kinematical structure of the individual clouds with statistical methods and perform a principal component analysis to search for correlations between the detected molecules. To investigate the nature of the molecular clouds along the line of sight to Sgr B2, we also used archival Mopra data. Results. We identify, on the basis of c-C3H2, 15 main velocity components along the line of sight to Sgr B2(N) and several components associated with the envelope of Sgr B2 itself. The c-C3H2 column densities reveal two categories of clouds. Clouds in Category I (3 kpc arm, 4 kpc arm, and some GC clouds) have smaller c-C3H2 column densities, smaller linewidths, and smaller widths of their column density PDFs than clouds in Category II (Scutum arm, Sgr arm, and other GC clouds). We derive opacity maps for the following molecules: c-C3H2, H13CO+, 13CO, HNC and its isotopologue HN13C, HC15N, CS and its isotopologues C34S and 13CS, SiO, SO, and CH3OH. These maps reveal that most molecules trace relatively homogeneous structures that are more extended than the field of view defined by the background continuum emission (about 15′′, that is 0.08–0.6 pc depending on the distance). SO and SiO show more complex structures with smaller clumps of size ~5–8′′. Our analysis suggests that the driving of the turbulence is mainly solenoidal in the investigated clouds. Conclusions. On the basis of HCO+, we conclude that most line-of-sight clouds towards Sgr B2 are translucent, including all clouds where complex organic molecules were recently detected. We also conclude that CCH and CH are good probes of H2 in both diffuse and translucent clouds, while HCO+ and c-C3H2 in translucent clouds depart from the correlations with H2 found in diffuse clouds.

scholarly journals Imaging Large– and Small–Scale Structures of the Far Ultraviolet Background with the Faust Instrument

1990 ◽  
Vol 139 ◽  
pp. 449-452 ◽  
Author(s):  
M. Lampton ◽  
S. Bowyer ◽  
J. M. Deharveng
Keyword(s):  
Angular Resolution ◽  
Photon Counting ◽  
Field Of View ◽  
Small Scale ◽  
Galactic Latitude ◽  
High Galactic Latitude ◽  
Photon Counting Detector ◽  
Scale Structures ◽  
Far Ultraviolet ◽  
Small Scale Structures

The FAUST telescope is an ultraviolet survey instrument that features a wide 8° field of view, ~1′ angular resolution, and a photon counting detector. Operating in the 1400–1800 Å band, it will be sufficiently sensitive to detect blue mv =17 objects in a single 20 minute night. The instrument is part of the ATLAS-1 shuttle mission, presently scheduled for flight in May 1991. A substantial number of high galactic latitude fields will be investigated, with particular emphasis on studies of the origin of the diffuse far UV background.

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