Product Perfect Codes and Steganography

A new coding technique to be used in steganography is evaluated. The performanceof this new technique is computed and comparisons with the well-known theoreticalupper bound, Hamming upper bound and basic LSB are established.

Modeling of Pressurizer Using APROS and TRACE Thermal Hydraulic Codes

Diplomityön tavoitteena on paineistimen yksityiskohtainen mallintaminen APROS- ja TRACE- termohydrauliikkaohjelmistoja käyttäen. Rakennetut paineistinmallit testattiin vertaamalla laskentatuloksia paineistimen täyttymistä, tyhjentymistä ja ruiskutusta käsittelevistä erilliskokeista saatuun mittausdataan. Tutkimuksen päätavoitteena on APROSin paineistinmallin validoiminen käyttäen vertailuaineistona PACTEL ATWS-koesarjan sopivia paineistinkokeita sekä MIT Pressurizer- ja Neptunus- erilliskokeita. Lisäksi rakennettiin malli Loviisan ydinvoimalaitoksen paineistimesta, jota käytettiin turbiinitrippitransientin simulointiin tarkoituksena selvittää mahdolliset voimalaitoksen ja koelaitteistojen mittakaavaerosta johtuvat vaikutukset APROSin paineistinlaskentaan. Kokeiden simuloinnissa testattiin erilaisia noodituksia ja mallinnusvaihtoehtoja, kuten entalpian ensimmäisen ja toisen kertaluvun diskretisointia, ja APROSin sekä TRACEn antamia tuloksia vertailtiin kattavasti toisiinsa. APROSin paineistinmallin lämmönsiirtokorrelaatioissa havaittiin merkittävä puute ja laskentatuloksiin saatiin huomattava parannus ottamalla käyttöön uusi seinämälauhtumismalli. Työssä tehdyt TRACE-simulaatiot ovat osa United States Nuclear Regulatory Commissionin kansainvälistä CAMP-koodinkehitys-ja validointiohjelmaa.

Construction and performance of network codes

El principal objectiu d'aquest treball és implementar i exposar una descripció teòrica per a diferents esquemes de Physical Layer Network Coding. Utilitzant un esquema bàsic com a punt de partida, el projecte presenta la construcció i l'anàlisis de diferents esquemes de comunicació on la complexitat va augmentant a mesura que anem avançant en el projecte. El treball està estructurat en diferents parts: primer, es presenta una introducció a Physical Layer Network Coding i a Lattice Network Codes. A continuació, s'introdueixen les eines matemàtiques necessàries per entendre el CF System. Després, s'analitza i implementa el primer esquema bàsic. A partir del qual, implementem una versió vectorial del CF System i una versió codificada amb un Hamming q-ari. Finalment, s'estudien i implementen diferents estratègies per millorar la matriu de coeficients A.

Les codes de l'obligations : méta-analyses pragmatologiques de l'application de méthodes en sciences sociales

Cette thèse rassemble une série de méta-analyses, c'est-à-dire d'analyses ayant pour objet des analyses produites par des sociologues (notamment celles résultant de l'application de méthodes de traitement des entretiens). Il s'agit d'une démarche réflexive visant les pratiques concrètes des sociologues. Celles-ci sont envisagées comme des activités gouvernées par des règles. Une part importante de cette thèse sera donc consacrée au développement d'un outil d'analyse « pragmatologique » (E. Durkheim), c'est-à-dire permettant l'étude des pratiques et des règles en rapport avec elles. Pour aborder les règles, la philosophie analytique d'inspiration wittgensteinienne apporte plusieurs propositions importantes. Les règles sont ainsi considérées comme des concepts d'air de famille : il n'y a pas de définitions communes recouvrant l'ensemble des règles. Pour étudier les règles, il convient alors de faire des distinctions à partir de leurs usages. Une de ces distinctions concerne la différence entre règles constitutives et règles régulatives : une règle constitutive crée une pratique (e.g. le mariage), alors qu'une règle régulative s'applique à des activités qui peuvent exister sans elle (e.g. les règles du savoir-vivre). L'activité méthodologique des sociologues repose et est contrainte par ces types de règles, qui sont pour l'essentiel implicites. Cette thèse vise donc à rendre compte, par la description et la codification des règles, du caractère normatif des méthodes dans les pratiques d'analyse de la sociologie. Elle insiste en particulier sur les limites logiques qu'instituent les règles constitutives, celles-ci rendant impossibles (et non pas interdites) certaines actions des sociologues. This thesis brings together a series of meta-analyzes, that is, analyzes that tackle analyzes produced by sociologists (notably those resulting from the application of methods in treating interviews). The approach is reflexive and aimed at the concrete practices of sociologists, considered as activities governed by rules. An important part of this thesis is therefore devoted to the development of a "pragmatological" analytical tool (Durkheim) to conduct a study of such practices and of the rules that govern them. To approach these rules, Wittgenstein-inspired analytic philosophy offers several important proposals. The rules are, at first, seen as concepts of family resemblance, assuming that there is no common definition accounting for all rules. In order to conduct the study of such rules, it is therefore necessary to discern how they are respectively used. One of these distinctions concerns the difference between constitutive rules and regulative rules: a constitutive rule creates a practice (for example marriage), while a regulative rule applies to activities that can exist outside of the rule (for example, the rules of etiquette). The methodological activity of sociologists relies on, and is constrained by these types of rules, which are essentially implicit. Through the description and codification of rules, this thesis aims to account for the normative character of methods governing analytical practices in sociology. Particular emphasis is on the logical limits established by constitutive rules, limits that render several of the sociologist's actions impossible (rather than forbidden).

Performance Analysis of Two Quantum Reaction Dynamics Codes: Time-Dependent and Time-Independent Strategies

The computer simulation of reaction dynamics has nowadays reached a remarkable degree of accuracy. Triatomic elementary reactions are rigorously studied with great detail on a straightforward basis using a considerable variety of Quantum Dynamics computational tools available to the scientific community. In our contribution we compare the performance of two quantum scattering codes in the computation of reaction cross sections of a triatomic benchmark reaction such as the gas phase reaction Ne + H2+ %12. NeH++ H. The computational codes are selected as representative of time-dependent (Real Wave Packet [ ]) and time-independent (ABC [ ]) methodologies. The main conclusion to be drawn from our study is that both strategies are, to a great extent, not competing but rather complementary. While time-dependent calculations advantages with respect to the energy range that can be covered in a single simulation, time-independent approaches offer much more detailed information from each single energy calculation. Further details such as the calculation of reactivity at very low collision energies or the computational effort related to account for the Coriolis couplings are analyzed in this paper.

The Impact of Supervisor's Advice, Codes of Conduct, Accountability and Moral Attentiveness of Individuals on Discriminatory Behaviour Against Immigrants.

Past studies on the personnel selection demonstrated that a supervisor's advice to discriminate can lead to compliant behaviours. This study had the aim to extend past findings by examining what can overcome the powerful influence of the hierarchy. 50 Swiss managers participated to an in-basket exercise. The main task was to evaluate Swiss candidates (in-group) and foreigners (out-groups: Spanish and Kosovo Albanians) and to select two applicants for a job interview. Main results were the effect of codes of conduct to prevent discrimination against out-group applicants in the presence of a supervisor's advice to prefer in-group members. But, when participants were accountable to an audience, this beneficial effect disappears because participants followed the supervisor's advice. The second aim was to assess if the difference in responses between participants was related to their difference in moral attentiveness. Results showed some significant relationships but not always in the direction expected.

Adquisició de les codes complexes finals del català per part d'alumnat panjabi: el mètode experimental

En aquest treball estudiem l’adquisició del català per part de parlants que tenen el panjabi com a primera llengua, concretament en relació amb les codes complexes de final de mot, per a aprenents d’un nivell inicial de català

Z2Z4-Additive Perdect Codes in Steganography

Steganography is an information hiding application which aims tohide secret data imperceptibly into a cover object. In this paper, we describe anovel coding method based on Z2Z4-additive codes in which data is embeddedby distorting each cover symbol by one unit at most (+-1-steganography). Thismethod is optimal and solves the problem encountered by the most e cientmethods known today, concerning the treatment of boundary values. Theperformance of this new technique is compared with that of the mentionedmethods and with the well-known rate-distortion upper bound to conclude thata higher payload can be obtained for a given distortion by using the proposedmethod.

Space–Time Block Codes and the Complexity of Sphere Decoding

In wireless communications the transmitted signals may be affected by noise. The receiver must decode the received message, which can be mathematically modelled as a search for the closest lattice point to a given vector. This problem is known to be NP-hard in general, but for communications applications there exist algorithms that, for a certain range of system parameters, offer polynomial expected complexity. The purpose of the thesis is to study the sphere decoding algorithm introduced in the article On Maximum-Likelihood Detection and the Search for the Closest Lattice Point, which was published by M.O. Damen, H. El Gamal and G. Caire in 2003. We concentrate especially on its computational complexity when used in space–time coding. Computer simulations are used to study how different system parameters affect the computational complexity of the algorithm. The aim is to find ways to improve the algorithm from the complexity point of view. The main contribution of the thesis is the construction of two new modifications to the sphere decoding algorithm, which are shown to perform faster than the original algorithm within a range of system parameters.