Plane Segmentation and Registration of Sparse and Heterogeneous Mobile Laser Scanning Point Clouds

This research discussed and analysed the limitations of different state of the art methods for point cloud processing tasks due to the sparseness and the heterogeneousness of the MLS point clouds. A novel plane detection and segmentation method for sparse MLS point clouds is proposed. Finally, the most suitable techniques for automatic registration of MLS sparse point clouds were determined based on a new error metric for evaluation

Solar variability over the Holocene period : disentangling geomagnetic and solar influences on a new continuous 10Be record from Little Dome C, Antarctica

Reliable information on solar activity over the Holocene period is important to predict the Sun in the future and to understand the mechanism behind the Sun-climate linkage. Presently, there are discrepancies in the proxy data of solar activity due to reasons that are not yet understood. This leads to major uncertainties in Holocene solar reconstructions. This PhD project aims to improve the Holocene solar reconstructions with a new dataset and a better reconstruction method. The results are be important for s lar and Sun-climate studies as well as for a better understanding of past changes in the carbon cycle.Cosmogenic radionuclides such as 10Be in ice cores and 14C in tree rings are the best-known proxies for solar activity far back in time. The radionuclide records reflect a combination of production, transportation and deposition processes (atmospheric circulation (10Be) and carbon cycle (14C)). Presently, the different radionuclide records show disagreements regarding their long-term (millennial-scales) changes for unknown reasons. Moreover, the radionuclide records are also influenced by long term changes in the geomagnetic field that are not well constrained. This leads to major uncertainties in reconstructions of past changes in solar activity.This thesis is based on new 10Be measurements from 759 ice chip samples drilled at the East Antarctic site called Little Dome C (LDC). The new 10Be record continuously covers the entire Holocene. A Bayesian model was also developed to disentangle solar activity and geomagnetic field influences on the radionuclide records. The model was applied on the new LDC 10Be data and also on the existing 10Be data from other ice cores and tree-ring 14C data. The reconstructions show consistent short-term variations (decadal- and centennial-scale) of solar activity while longterm variations (multi-millennial-scale) are still uncertain. Long-term discrepancies are present among the 10Be records and the 14C data, especially for the last 4 ka. We also found hints of a polar bias effect that dampens the geomagnetic field influence on Antarctic 10Be records but the effect is absent in a Greenland 10Be record. These results point to a difference in the transportation mode of 10Be toward the different ice core sites and an influence of the carbon cycle changes on the 14C data

Rational authentication protocols and their use in financial transactions

We use ideas from game theory to improve two families of authentication protocols, namely password-based and manual authentication schemes. The protocols will be transformed so that even if an intruder attacks different protocol runs between honest nodes, its expected payoff will still be lower than when it does not attack. A rational intruder, who always tries to maximise its payoff, therefore has no incentive to attack any protocol run among trustworthy parties. To illustrate the use of our method, we present a case study relating to the password-based authentication stage of on-line banking, where passwords are chosen either randomly or biasedly by, e.g., humans. For the latter we use the publicly available 32 million passwords of the social gaming network website RockYou as the source of human-selected passwords

Rational authentication protocols

ABSTRACT We use ideas from game theory to improve two families of authentication protocols, namely password-based and manual authentication schemes. The protocols will be transformed so that even if an intruder attacks different protocol runs between honest nodes, its expected payoff will still be lower than when it does not attack. A rational intruder, who always tries to maximise its payoff, therefore has no incentive to attack any protocol run among trustworthy parties

Rapid Prototyping for Sheet Metal Products

The aim of this chapter is to evaluate and predict forming limit and then to improve and develop the incremental sheet metal forming (ISMF) processes for complex surface products of sheet metal. The theoretical study was first overviewed and synthesized in order to recognize the effect of geometry, technology parameters, and processing conditions on ISMF process. Finite element method (FEM) simulation study was then used to compare the accuracy of constitutive material models and fracture criteria and propose new equations in order to improve the prediction of FEM simulation for incremental sheet metal forming process. To develop a new technique for improving the formability of sheet metal using ISMF, FEM was also adopted to reduce the cost and time of research. The basic experimental studies were performed to determine the input data for FEM simulation such as tensile data, fracture parameters, and so on. To investigate and compare the simulation results, the incremental sheet metal forming processes for complex shapes were also conducted

public-private sector wage differentials for males and females in vietnam

This study examines public administration-private wage differentials and SOEs-private wage differentials for males and females. Based on data from Vietnam Living Standards Survey in 2002 (VLSS 2002), wage equations with and without selectivity correction are estimated by sector of employment for males and females. From these results, the study compares the wage structure by sector of work for males and females. Oaxaca-Blinder decomposition of the public administration-private sector wage differentials and the State-Owned Enterprises (SOEs)-private sector wage differentials are carried out. Results, which are controlled for observed characteristics and selection bias, indicate some main points. For men, public workers are paid lower than private workers. For women, public administration wages are lower than private wages. However, SOE wages are higher than private wages for women. The wage differential is mostly due to the differential in characteristics in which public workers have richer characteristics than private workers. In these worker characteristics, education is the most important element accounting for wage differentials. Besides, there are differences in returns to characteristics by sector of work for men and for women. Furthermore, the total unexplained differential has a large contribution of the wage differential in the constant term of public administration vs. private sector and SOE vs. private sector for men and women

Public-Private Sector Wage Differentials for Males and Females in Vietnam

This study examines public administration-private wage differentials and SOEs-private wage differentials for males and females. Based on data from Vietnam Living Standards Survey in 2002 (VLSS 2002), wage equations with and without selectivity correction are estimated by sector of employment for males and females. From these results, the study compares the wage structure by sector of work for males and females. Oaxaca-Blinder decomposition of the public administration-private sector wage differentials and the State-Owned Enterprises (SOEs)-private sector wage differentials are carried out. Results, which are controlled for observed characteristics and selection bias, indicate some main points. For men, public workers are paid lower than private workers. For women, public administration wages are lower than private wages. However, SOE wages are higher than private wages for women. The wage differential is mostly due to the differential in characteristics in which public workers have richer characteristics than private workers. In these worker characteristics, education is the most important element accounting for wage differentials. Besides, there are differences in returns to characteristics by sector of work for men and for women. Furthermore, the total unexplained differential has a large contribution of the wage differential in the constant term of public administration vs. private sector and SOE vs. private sector for men and women

public-private sector wage differentials for males and females in vietnam

This study examines public administration-private wage differentials and SOEs-private wage differentials for males and females. Based on data from Vietnam Living Standards Survey in 2002 (VLSS 2002), wage equations with and without selectivity correction are estimated by sector of employment for males and females. From these results, the study compares the wage structure by sector of work for males and females. Oaxaca-Blinder decomposition of the public administration-private sector wage differentials and the State-Owned Enterprises (SOEs)-private sector wage differentials are carried out. Results, which are controlled for observed characteristics and selection bias, indicate some main points. For men, public workers are paid lower than private workers. For women, public administration wages are lower than private wages. However, SOE wages are higher than private wages for women. The wage differential is mostly due to the differential in characteristics in which public workers have richer characteristics than private workers. In these worker characteristics, education is the most important element accounting for wage differentials. Besides, there are differences in returns to characteristics by sector of work for men and for women. Furthermore, the total unexplained differential has a large contribution of the wage differential in the constant term of public administration vs. private sector and SOE vs. private sector for men and women