Template Protection For 3D Face Recognition

The human face is one of the most important biometric modalities for automatic authentication. Three-dimensional face recognition exploits facial surface information. In comparison to illumination based 2D face recognition, it has good robustness and high fake resistance, so that it can be used in high security areas. Nevertheless, as in other common biometric systems, potential risks of identity theft, cross matching and exposure of privacy information threaten the security of the authentication system as well as the user\\u27s privacy. As a crucial supplementary of biometrics, the template protection technique can prevent security leakages and protect privacy. In this chapter, we show security leakages in common biometric systems and give a detailed introduction on template protection techniques. Then the latest results of template protection techniques in 3D face recognition systems are presented. The recognition performances as well as the security gains are analyzed

An Experimental Study on Effect of Steel Corrosion on the Bond–Slip Performance of Reinforced Concrete

This paper studied the effects of reinforcement corrosion on bond performance between rebar and concrete. Tests were carried out to evaluate the degradation of bond between reinforcing steel and concrete for different corrosion levels of reinforcing steel. A series of 20 specimens of different concrete strength with various reinforcing steel corrosion levels were designed and manufactured. Each specimen was casted as a 200-mm concrete cube, and a steel rebar was centrally embedded with two stirrups around it. The steel rebar were corroded using an electrochemical accelerated corrosion technique. The corrosion crack opening width and length were recorded after the corrosion process. Then, monolithic pull-out loading tests were carried out on the specimens. The effects of reinforcement corrosion on crack opening, maximum bond stress, and energy dissipation were discussed in detail. It was found that reinforcement corrosion has non-negligible effects on bond performance of reinforcing bar in concrete

Investigation on Internal Short Circuit Identification of Lithium-Ion Battery Based on Mean-Difference Model and Recursive Least Square Algorithm

Electric vehicles powered by lithium-ion batteries take advantages for urban transportation. However, the safety of lithium-ion battery needs to be improved. Self-induced internal short circuit of lithium-ion batteries is a serious problem which may cause battery thermal runaway. Accurate and fast identification of internal short circuit is critical, while difficult for lithium-ion battery management system. In this study, the influences of the parameters of significance test on the performance of an algorithm for internal short circuit identification are evaluated experimentally. The designed identification is based on the mean-difference model and the recursive least square algorithm. First, the identification method is presented. Then, two characteristic parameters are determined. Subsequently, the parameters of the significance calculation are optimized based on the measured data. Finally, the effectiveness of the method for the early stage internal short circuit detection is studied by an equivalent experiment. The results indicate that the detection time can be shortened significantly via a proper configuration of the parameters for the significance test

Prolonged insula activation during perception of aftertaste

Although a critical component of taste perception, the neural basis of aftertaste perception has yet to be elucidated with neuroimaging. This functional neuroimaging study assessed the temporal dynamics of neural responses to sucrose and aspartame in eight healthy volunteers. Aspartame has a sweetness flavor profile similar to sucrose but a longer temporal profile. Participants underwent functional magnetic resonance imaging while tasting sucrose and aspartame solutions administered through a magnetic resonance imaging compatible delivery device. The insula showed significantly longer activation to aspartame than sucrose, whereas other regions activated by the task (somatosensory cortex thalamus, amygdala, and basal ganglia) did not show a prolonged response to either tastant These findings implicate the insula in aftertaste perception. NeuroReport 20:245-250 (C) 2009 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins

Video Fingerprinting Algorithm

Increasing amounts and various formats of multimedia data require technologies to automatically identify its content. Cryptographic hash functions can not be used for multimedia content identification or verification as they are sensitive to common video processing operations e.g. compression, colour adjustment etc. In this case, fingerprinting, also called perceptual hash functions, that consider perceptual similarity are applicable. Fingerprinting converts large data to a short digest, which is used to identify original data. This diploma thesis describes some of the different existing approaches for video data. One reference implementation based on Philips' algorithm is investigated. The fingerprints are extracted from the spatio- temporal differencing of mean luminance. It is shown how this method can be improved by using a simple similarity measure. The performance of the algorithms are analysed. The algorithm using similarity shows increased reliability of video identification both in robustness and discriminating capabilities Die Anzahl und verschiedene Repräsentation verlangen Techniken, die automatisch diese Inhalten identifizieren können. Kryptographische Hashfunktionen können nicht zu Identifikation und Verifikation der Multimedia-Inhalten benutzt werden. Sie sind nicht robust gegen normale Videoverarbeitung, wie z.B. Kompression oder Farbeneinstellung. In diesen Fälle sind Fingerprinting- Verfahren, auch wahrnehmungsbasierte Hashfunktion genannt, die wahrnehmungsbasierte Ähnlichkeiten beachten, besser geeignet. Fingerprinting-Verfahren konvertieren große Daten zu kleinen Zusammenfassungen, die zur Identifikation der Daten genutzt werden können. Diese Diplomarbeit beschreibt existierende Video-Fingerprinting-Verfahren. Eine Referenzimplementierung, die auf Philips' Algorithmen basiert, wird analysiert. Hier werden die Fingerprints von räumliche und zeitliche Differenz der Leuchtdichtemittelwerten bestimmt. Es wird gezeigt, wie diese Verfahren bei Verwendung eines einfachen Ähnlichkeitsmasses verbessert werden kann. Die Leistung der Algorithmen wird analysiert. Der neu entwickelte Algorithmus, der auf die Ähnlichkeit basiert, hat eine verbesserte Zuverlässigkeit bzgl. einer Robustheit als auch seiner Unterscheidbarkeit

Privacy and Security Assessment of Biometric Template Protection

Biometrics enables convenient authentication based on a person's physical or behavioral characteristics. In comparison with knowledge- or token-based methods, it links an identity directly to its owner. Furthermore, it can not be forgotten or handed over easily. As biometric techniques have become more and more efficient and accurate, they are widely used in numerous areas. Among the most common application areas are physical and logical access controls, border control, authentication in banking applications and biometric identification in forensics. In this growing field of biometric applications, concerns about privacy and security cannot be neglected. The advantages of biometrics can revert to the opposite easily. The potential misuse of biometric information is not limited to the endangerment of user privacy, since biometric data potentially contain sensitive information like gender, race, state of health, etc. Different applications can be linked through unique biometric data. Additionally, identity theft is a severe threat to identity management, if revocation and reissuing of biometric references are practically impossible. Therefore, template protection techniques are developed to overcome these drawbacks and limitations of biometrics. Their advantage is the creation of multiple secure references from biometric data. These secure references are supposed to be unlinkable and non-invertible in order to achieve the desired level of security and to fulfill privacy requirements. The existing algorithms can be categorized into transformation-based approaches and biometric cryptosystems. The transformation-based approaches deploy different transformation or randomization functions, while the biometric cryptosystems construct secrets from biometric data. The integration in biometric systems is commonly accepted in research and their feasibility according to the recognition performance is proved. Despite of the success of biometric template protection techniques, their security and privacy properties are investigated only limitedly. This predominant deficiency is addressed in this thesis and a systematic evaluation framework for biometric template protection techniques is proposed and demonstrated: Firstly, three main protection goals are identified based on the review of the requirements on template protection techniques. The identified goals can be summarized as security, privacy protection ability and unlinkability. Furthermore, the definitions of privacy and security are given, which allow to quantify the computational complexity estimating a pre-image of a secure template and to measure the hardness of retrieving biometric data respectively. Secondly, three threat models are identified as important prerequisites for the assessment. Threat models define the information about biometric data, system parameters and functions that can be accessed during the evaluation or an attack. The first threat model, so called naive model, assumes that an adversary has very limited information about a system. In the second threat model, the advanced model, we apply Kerckhoffs' principle and assume that essential details of algorithms as well as properties of biometric data are known. The last threat model assumes that an adversary owns large amount of biometric data and this allows him to exploit inaccuracy of biometric systems. It is called the collision threat model. Finally, a systematic framework for privacy and security assessment is proposed. Before an evaluation process, protection goals and threat models need to be clarified. Based on these, the metrics measuring different protection goals as well as an evaluation process determining the metrics will be developed. Both theoretical evaluation with metrics such as entropy, mutual information and practical evaluation based on individual attacks can be used. The framework for privacy and security assessment is applied on the biometric cryptosystems: fuzzy commitment for 3D face and iris recognition is assessed. I develop my own 3D face recognition algorithm based on the depth distribution of facial sub-surfaces and integrate it in the fuzzy commitment scheme. The iris recognition is based on an open source algorithm using Gabor filter. It is implemented in the fuzzy commitment scheme with the two layer coding method as proposed by Hao et al. Both features, the 3D face features and the iris features, represent local characteristics of the modalities. Thus, strong dependency within these features is observed. The second order dependency tree is applied to describe the distribution of 3D face features. The Markov model is applied to characterize the statistical properties of iris features. Thus, security and privacy of these algorithms can be measured with theoretical metrics. Due to strong feature dependency, the achieved security is much smaller than the secret size, which is the assumed security in a perfect secure case with uniformly identically distributed features. Moreover, the unlinkability is analyzed. The analysis shows that these protected systems are less vulnerable to leakage amplification. However, the secure templates contain much personal identifiable information. We demonstrate the attacks, which can identify a subject by linking auxiliary data stored in his secure templates. Cross matching is assessed with the performance of these attacks. Additionally, the characteristics of iris features is exploited to perform an attack retrieving features from secure templates. The efficiency of the practical attack confirms the result of the theoretical assessment of privacy with conditional entropy. The coding process plays a very important role for the security and privacy properties in the fuzzy commitment scheme. Designing a coding method should not only focus on the improvement of code rate. As shown in this thesis, security and privacy properties can be enhanced significantly by changing the dependency pattern in iris features and 3D face features. Therefore, the coding process should be adapted to properties of the underlying biometric features to increase the security and privacy performance. The security and privacy assessment within this thesis is completed by a comparison of two fuzzy commitment algorithms with the fuzzy vault algorithm for fingerprint recognition. Here, different threat models as well as the corresponding protection goals are considered. The fuzzy vault system has the best performance regarding security and irreversibility of biometric features. However, all of these systems are vulnerable to cross matching. The comparison results show that the proposed evaluation framework provides the fundamental basis for benchmarking different template protection algorithms. The proposed framework is also validated with the existing security analysis on transformation-based approaches. Unlike the analysis on biometric cryptosystems, the security is dependent on the hardness of transformation functions or randomization processes. Therefore, the presented analysis is based on efficiency of different kinds of attacks, which measure different protection goals in the appropriate threat models. The security of these approaches depends on the transformation parameters. The knowledge of these parameters allows generating a pre-image, while it is still hard to estimate the original biometric features practically. However, privacy leakage amplifications are still possible. This thesis defines a systematic evaluation framework, which adheres to essential criteria and requirements of biometric template protection techniques. Its applicability is demonstrated with the analysis of template protection algorithms for different biometric modalities. The assessment presented in this thesis is fundamental for a thorough analysis. Furthermore, it provides provable evidence on security and privacy performance. Therefore, it is the fundamental tool for technical innovation and improvement and helps system designers in selecting a suitable template protection algorithm for their applications and needs. It creates a basis for certification and benchmarking of biometric template protection

Enhanced performance on CO2 adsorption and release induced by structural transition that occurred in TBAB center dot 26H(2)O hydrates

The applications of ionic clathrate hydrates have greatly improved the efficiency and the conditions required for hydrate-based CO2 capture, but high energy input for hydrate growth and complicated treatment of hydrate slurry still hinder their commercial use. Here we chose TBAB center dot 26H(2)O hydrate particles to adsorb CO2 molecules instead of TBAB solutions below 2 MPa and release them at ambient pressure. Results showed that the TBAB center dot 26H(2)O hydrate could adsorb CO2 without induction time and enhance the gas storage capacity by structural transition, especially under high pressure. By using in situ Raman, CO2 molecules were found to fill the empty cages in TBAB center dot 26H(2)O hydrate first, the formed nCOZTBAB center dot 26H(2)O hydrate then converted to nCOZTBAB center dot 38H(2)O and TBAB center dot 2(1)/3H2O hydrates at 2 MPa. Macroscopic measurements revealed that around 20 volume of CO2 in standard state could be adsorbed by 1 volume of TBAB center dot 26H(2)O hydrate sample at 1 MPa, but this volume ratio could reach 67 v/v at 2 MPa where structural change was thought to take place. The pressurized CO2 trapped in hydrate phase was assumed to destroy the structure of TBAB center dot 26H(2)O hydrate easily, and force the water molecules to form a structure that more compatible with CO2 molecules. This may explain why nCOZTBAB center dot 26H(2)O hydrates barely grow from TBAB solutions when pressurized CO2 is injected. In the CO2 release process, the nCOZTBAB center dot 38H(2)O and TBAB center dot 2(1)/3H2O hydrates quickly transformed back to nCO(2)center dot TBAB center dot 26H(2)O hydrates and 60-80% of the captured CO2 could be released. Combing with their excellent gas selectivity, TBAB center dot 26H(2)O hydrate particles would be an ideal material for hydrate-based CO2 capture