Search

A new method for the co-registration of single tree data in forest stands and forest plots applicable to static as well as dynamic data capture is presented. This method consists of a stem diameter weighted linking algorithm that improves the linking accuracy when operating on diverse diameter stands with stem position errors in the single tree detectors. A co-registration quality metric threshold, QT, is also introduced which makes it possible to discriminate between correct and incorrect stem map co-registrations with high probability (>99%). These two features are combined to a simultaneous location and mapping-based co-registration method that operates with high linking accuracy and that can handle sensors with drifting errors and signal bias. A test with simulated data shows that the method has an 89.35% detection rate. The statistics of different settings in a simulation study are presented, where the effect of stem density and position errors were investigated. A test case with real sensor data from a forest stand shows that the average nearest neighbor distances decreased from 1.90 m to 0.51 m, which indicates the feasibility of this method.

Validerat; 20110224 (anonymous)

I media talas det ofta om att antalet ungdomar vilka provar och använder sig av drogen Ecstasy i samband med dans- och ravepartyn ökar drastiskt runt om i vår värld. Målet med denna forskningsöversikt är därför att med hjälp av forskningsstudier från 2003 och framåt, söka få en bild av viken grupp av ungdomar som befinner sig i riskzonen för att hamna i ett missbruk av Ecstasy, samt vilka riskfaktorer och risker som berör dessa ungdomar. Metoden som använts för att besvara dessa frågor är en forskningsöversikt som bygger på elva forskningsartiklar i ämnet. Studien berör i huvudsak tre olika länder i var sina världsdelar. Den teori som används i analysen av studien är ett globalt, socialt och kulturellt perspektiv, som inkluderar såväl sociala som kulturella teorier. Sammanfattningen av studien visar att såväl de psykiska, fysiska och sociala riskfaktorerna i stort sett är likartade för de berörda ungdomsgrupperna i samtliga av dessa länder. Det vill säga att ungdomar som brukar Ecstasy, eller ligger i riskzonen för ett missbruk av drogen, möter ungefär samma sociala problematik och att de psykiska och fysiska biverkningarna av drogen är de samma oavsett vilket land de bor i. Då det gäller sociala riskgrupper på global nivå, har det i översikten visat sig att den övervägande delen är de ungdomar som deltar i dans- och ravepartyn, oavsett etnisk bakgrund och kön, vilka under barndomen uppvisat symptom på ångest och/eller depression och kommer från medel- eller övre medelklass, löper störst risk att komma i kontakt med Ecstasy. Av dessa anledningar ökar även risken för dessa ungdomar att hamna i ett missbruk av drogen. En annan orsak till denna utsatthet beror på att ungdomar från denna samhällsklass i högre utsträckning deltar i så kallade ravepartyn och liknande tillställningar, än ungdomar från andra samhällsklasser.

The TreeD © software, version 0.8, is an application that loads an aerial or satellite image and detects trees by template matching. The software is developed at the Remote Sensing Laboratory, Swedish University of Agricultural Sciences ( SLU) in Umea, Sweden. This is beta software and the methods and algorithms are continuously being improved upon. Please report any errors you find in the software to the Remote Sensing Laboratory. The algorithms for tree detection used in the application are based on a PhD thesis by Richard J ames Pollock (1996), University of British Columbia, Canada. The application is build upon two software libraries, Intel® Image Processing Library, IPL ©and wxWindows ©. The I PL is used for image processing and wx Windows is used as a graphical user interface. The report contains three major sections, a manual, a method description and a software description. The manual is for someone, without any prior knowledge of template matching, who wants to run the software. The method and software descriptions are for someone that wants to build a similar application as Tree D or as a support for in-house development at the Remote Sensing Laboratory. The TreeD 0.8 application is available at the Remote Sensing Laboratory, SLU and is primarily used as a research tool for single tree detection. The software runs on a Microsoft® Windows 2 000 workstation. The application binary depends on the Intel® Image Processing Library, IPL © DLLs and consequently they need to be put into the same folder as the program. All of these binaries can be found at SLU. The input to the application is an aerial/satellite image (central or orthogonal projection), a tree library, information about the camera and solar positions , and a path to a directory to put the results in. The current status of the input variables can be viewed and changed before starting the correlation of the image. The output from the application consists of three text files , status. txt, treelist.txt and probable_treelist.txt. I f there are old files with these names at the result directory they will be overwritten. To save a new batch you can either rename the oldfiles or use a new result directory. ·· The application assumes that the terrain is fairly flat and that the camera is positioned approximately in a nadir view. I f these conditions are not fulfilled the accuracy of the positioning and detection of the trees will decrease.

Pulsed Holographic Interferometry (HI), is used to record propagating transient bending waves in plates and shells. These waves are generated mechanically by impact of a small steel sphere or optically by focusing a high energy laser pulse at the surface of the tested object. Bending waves propagate with different speeds in different directions if the object material is anisotropic. The wave pattern is also affected by thickness and density variations as well as by defects present in the material. These phenomena are used in non destructive testing of products. In part one of this thesis, pulsed HI is applied for the study of mechanical properties of sheets of paper and corrugated board. This method can be used to detect anisotropy, to determine principle directions, and to examine local variations and defects in paper. The local dynamic behaviour of the board is different from what can be expected from static testing. Mechanical defects in board can be identified. A new impact method is developed, where transient bending waves are generated and recorded by the same pulsed laser. The proposed method can be developed into a commercial measuring device of mechanical properties of paper. In part two, HI is applied to wave propagation in tubes and rings. These are made out of steel, aluminium and fibre reinforced epoxy. A conical mirror is placed axially inside the tube. Axial illumination and axial observation directions make it possible to view the circumference of the tube with a high and constant sensitivity to radial deformation. The resulting interferograms, which have an unusual perspective, are captured with a CCD-camera connected to a computer. The images are thereafter numerically transformed into an unwrapped strip of the tube wall and displayed as a 3D-displacement map. This makes the interpretation of the interferograms simple. The method can be used in non-destructive testing of tubes. In part three, the impact from a laser pulse on a plate, is studied more closely. A high energy laser pulse focused at a steel plate is transferring both mechanical impulse and local thermal energy to the plate. The mechanical impulse creates propagating bending waves in the plate. The heated spot at the plate surface creates thermal stresses which give rise to an out-of-plane deformation of the plate. These deformations are superimposed. The effects are studied using HI to record the deformation. The possibility of creating mechanical waves optically has many advantages. The method is of noncontact character, the laser produces an impulse with short duration and the technique can be applied on-line in the production control. Godkänd; 1994; 20070429 (ysko)