37 research outputs found
Performance of 3D PPN against arbitrarily maneuvering target for homing phase
The performance analysis of the 3-D pure proportional navigation (PPN) guidance law was traditionally conducted by considering the cross-coupling effect of two independent 2-D PPN laws in the pitch and yaw planes. This could increase the complexity of the analysis and lead to conservative analysis results, especially when the target has maneuverability. To mitigate this issue, this article theoretically analyzes the performance of 3-D PPN directly on a rotating engagement plane using a Lyapunov-like approach. Considering practical issues, the analysis includes not only capturability, but also upper-bounds of heading error, line-of-sight rate, commanded acceleration, and closing speed. The analysis results obtained are also demonstrated by using numerical simulation examples. Compared to the previous studies providing the least conservative results, the analysis procedure is significantly simplified and the results are proven to be more practical and less conservativ
Sensors, measurement fusion and missile trajectory optimisation
When considering advances in âsmartâ weapons it is clear that air-launched systems have adopted an integrated approach to meet rigorous requirements, whereas air-defence systems have not. The demands on sensors, state observation, missile guidance, and simulation for air-defence is the subject of this research. Historical reviews for each topic, justification of favoured techniques and algorithms are provided, using a nomenclature developed to unify these disciplines. Sensors selected for their enduring impact on future systems are described and simulation models provided. Complex internal systems are reduced to simpler models capable of replicating dominant features, particularly those that adversely effect state observers. Of the state observer architectures considered, a distributed system comprising ground based target and own-missile tracking, data up-link, and on-board missile measurement and track fusion is the natural choice for air-defence. An IMM is used to process radar measurements, combining the estimates from filters with different target dynamics. The remote missile state observer combines up-linked target tracks and missile plots with IMU and seeker data to provide optimal guidance information. The performance of traditional PN and CLOS missile guidance is the basis against which on-line trajectory optimisation is judged. Enhanced guidance laws are presented that demand more from the state observers, stressing the importance of time-to-go and transport delays in strap-down systems employing staring array technology. Algorithms for solving the guidance twopoint boundary value problems created from the missile state observer output using gradient projection in function space are presented. A simulation integrating these aspects was developed whose infrastructure, capable of supporting any dynamical model, is described in the air-defence context. MBDA have extended this work creating the Aircraft and Missile Integration Simulation (AMIS) for integrating different launchers and missiles. The maturity of the AMIS makes it a tool for developing pre-launch algorithms for modern air-launched missiles from modern military aircraft.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Aerial Vehicles
This book contains 35 chapters written by experts in developing techniques for making aerial vehicles more intelligent, more reliable, more flexible in use, and safer in operation.It will also serve as an inspiration for further improvement of the design and application of aeral vehicles. The advanced techniques and research described here may also be applicable to other high-tech areas such as robotics, avionics, vetronics, and space
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Understanding past and future changes in northern Fennoscandian snow cover.
In this project, a combination of field measurements, remote sensing data and regional climate model outputs were used to study recent and projected future changes in Northern Fennoscandian snow cover. The research questions considered in this thesis are: What are the uncertainties in remote sensing and climate modelling datasets used in snow studies? How has snow cover been changing since the 1960s and how will it change over the next century, at a regional level over Northern Fennoscandia?
Field measurements were made over two field seasons in the Khibiny Mountains in Arctic Russia. This ground data was used to gain an understanding of snow cover behaviour in the Western Mountain Regions (WMR) of the Kola Peninsula and to ground-truth 500 m resolution satellite data (MODIS: Moderate Resolution Imaging Spectroradiometer) snow products. The overall root mean square error (RMSE) for both MODIS instruments was found to be less than 10 %. The ground-truthed MODIS snow product was then used with station data to analyse past changes in snow cover in the WMR over the past 16 years. Though there is high inter-annual and spatial variability in the long-term snow cover trends in the WMR, overall, the duration of the snow cover season has increased at lower elevations and decreased at higher elevations.
Field measurements and MODIS data were used in the sensitivity analysis of the Weather Research and Forecasting (WRF) regional climate model. Twelve experiments with different physics parameterisations were run over the first field season, and a statistical scores evaluation was undertaken to determine the optimised parameter setup for modelling snow in the region. Three CMIP5 (Coupled Model Intercomparison Project 5) models were used to force WRF in historical (1990 - 1999) and two future climate (2090 - 2099) emission scenarios over Northern Fennoscandia. Outputs from the historical runs were compared to data from 10 stations across Northern Fennoscandia in order to further validate WRF. WRF makes excellent temperature estimates, with a mean bias in the yearly mean temperature outputs of the runs of -1.89 °C. The precipitation outputs are less accurate with values often higher than observations, especially for extreme precipitation events (CMIP5 âensembleâ mean RMSE of 24.0 mm for 20 + mm precipitation events).
Finally, the future runs were compared to historical runs to study projected future changes in temperature, precipitation, snowfall and snow cover. The three models give a range of different future predictions for regional climate change over Northern Fennoscandia. However, all CMIP5 models agree that in both emission scenarios mean snow cover duration will be lower over 2090 to 2099 than it was between 1990 and 1999. Importantly, changes in temperature, precipitation and snowfall are all higher, and snow cover is most impacted, in the higher emission scenario. RCP 8.5 consistently sees a higher decrease in solid precipitation than RCP 4.5 at all stations, and for all models and seasons, for example. Thus, aiming to reduce greenhouse gas emissions is still crucial to reducing anthropogenic impact on Northern Fennoscandian snow.Funded by NERC PhD studentship NE/L002507/
Shortest Route at Dynamic Location with Node Combination-Dijkstra Algorithm
Abstractâ Online transportation has become a basic
requirement of the general public in support of all activities to go
to work, school or vacation to the sights. Public transportation
services compete to provide the best service so that consumers
feel comfortable using the services offered, so that all activities
are noticed, one of them is the search for the shortest route in
picking the buyer or delivering to the destination. Node
Combination method can minimize memory usage and this
methode is more optimal when compared to A* and Ant Colony
in the shortest route search like Dijkstra algorithm, but canât
store the history node that has been passed. Therefore, using
node combination algorithm is very good in searching the
shortest distance is not the shortest route. This paper is
structured to modify the node combination algorithm to solve the
problem of finding the shortest route at the dynamic location
obtained from the transport fleet by displaying the nodes that
have the shortest distance and will be implemented in the
geographic information system in the form of map to facilitate
the use of the system.
Keywordsâ Shortest Path, Algorithm Dijkstra, Node
Combination, Dynamic Location (key words
Report of the Secretary of War; being part of the message and documents communicated to the two Houses of Congress at the beginning of the third session of the Forty-sixth Congress, 1880
Annual Message to Congress with Documents; Pres. Hayes. 6 Dec. HED 1, 46-3, vl-12, 10,587p. [1951-1962) Indian education; Ute agreement; end of hostilities of the Apaches, and Sitting Bull\u27s band of Sioux; allotment; annual report of the Sec.of War (Serials 1952-1957); annual report of the Sec. of Interior (Serials 1959-1961); annual report of the Gen. Land Office (Serial 1959); annual report of the CIA (Serial 1959), including Indian police, railroads through Indian lands, invasion of Indian Territory, and reports of Supts. and agents; etc
Aircraft-borne spectroscopic limb measurements of trace gases absorbing in the UV-A spectral range : investigations of bromine monoxide in the Arctic troposphere
Reactive halogen species (i.e., RHS=X, XO, X2, XY, OXO, HOX, XONO2, XNO2, with X,Y being I, Br and Cl) are known to be key compounds for the oxidation capacity of the troposphere, affecting the lifetime of relevant species such as O3, HOx, NOx, hydrocarbons, dimethylsulfide and gaseous elementary mercury. Furthermore, recent observations link iodine species to the formation of new aerosol particles. This work aims at the characterization of the abundance of BrO in the Arctic troposphere during the spring season, when the auto-catalytic release of bromine species from sea ice related halides is known to cause tropospheric Ozone Depletion Events (ODEs). A novel limb scanning mini-DOAS spectrometer for the detection of UV/vis absorbing radicals (e.g., O3, BrO, IO) was deployed on the DLR-Falcon (Deutsches Zentrum fĂŒr Luft- und Raumfahrt) aircraft and tested during a field campaign that took place at Svalbard (78°N) in spring 2007. Herein, a new algorithm for inferring concentration vertical profiles of tropospheric trace gases from aircraft-borne DOAS limb observations is presented, characterized and validated through the profile retrieval of the UV-A absorber O4. The method is then applied for retrieving tropospheric vertical profiles of BrO during the polar campaign. For deployments during ODEs, the retrieved BrO vertical profiles consistently indicate high BrO mixing ratios (~ 15 pptv) within the boundary layer, low BrO mixing ratios (< 1.5 pptv) in the free troposphere, occasionally enhanced BrO mixing ratios in the upper troposphere (~ 1.5 pptv), and increasing BrO mixing ratios with altitude in the lowermost stratosphere. These findings are well in agreement with satellite and balloon-borne soundings of total and partial BrO atmospheric column densities. Moreover, the capabilities of the aircraft-borne measurements are further exploited by analyzing the sources, photochemistry and transport processes of BrO in the boundary layer above the sea ice
City of Pocatello v. Idaho Clerk\u27s Record v. 8 Dckt. 37723
https://digitalcommons.law.uidaho.edu/idaho_supreme_court_record_briefs/3719/thumbnail.jp