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Matter Waves in Reduced Dimensions: Dipolar-Induced Resonances and Atomic Artificial Crystals
No full textThe experimental achievement of Bose-Einstein condensation and Fermi degeneracy with ultracold gases boosted tremendous progresses both in theoretical methods and in the development of new experimental tools. Among them, intriguing possibilities have been opened by the implementation of optical lattices: periodic potentials for neutral atoms created by interfering laser beams. Degenerate gases in optical lattices can be forced in highly anisotropic traps, reducing the effective dimensionality of the system. From a fundamental point of view, the behavior of matter waves in reduced dimensions sheds light on the intimate properties of interparticle interactions. Furthermore, such reduced-dimensional systems can be engineered to quantum-simulate fasci- nating solid state systems, like bidimensional crystals, in a clean and controllable environment. Motivated by the exciting perspectives of this field, we devote this Thesis to the theoretical study of two systems where matter waves propagate in reduced dimensions.
The long-range and anisotropic character of the dipole-dipole interaction critically affects the behavior of dipolar quantum gases. The continuous experimental progresses in this flourishing field might lead very soon to the creation of degenerate dipolar gases in optical potentials. In the first part of this Thesis, we investigate the emergence of a single dipolar-induced resonance in the two-body scattering process in quasi-one dimensional geometries. We develop a two-channel approach to describe such a resonance in a highly elongated cigar-shaped harmonic trap, which approximates the single site of a quasi-one-dimensional optical lattice. At this stage, we develop a novel atom-dimer extended Bose-Hubbard model for dipolar bosons in this quasi-one-dimensional optical lattice. Hence we investigate the T = 0 phase diagram of the model by exact diagonalization of a small-sized system, highlighting the effects of the dipolar-induced resonance on the many-body behavior in the lattice.
In the second part of the Thesis, we present a general scheme to realize cold-atom quantum simulators of bidimensional atomic crystals, based on the possibility to independently trap two different atomic species. The first one constitutes a two-dimensional matter wave which interacts only with the atoms of the second species, deeply trapped around the nodes of a two-dimensional optical lattice. By introducing a general analytic approach, we investigate the matter-wave transport properties. We propose some illustrative applications to both Bravais (square, triangular) and non-Bravais (graphene, kagomé) lattices, studying both ideal periodic systems and experimental- sized, eventually disordered, ones. The features of the artificial atomic crystal critically depend on the two-body interspecies interaction strength, which is shown to be widely tunable via 0D-2D mixed-dimensional resonances.
Keywords: matter waves, reduced dimensions, dipolar-induced resonances, mixed-dimensional resonances, extended Bose-Hubbard model, atomic artificial crystals
Production and performance of Cu-based anode-supported SOFC
No full textTubular SOFCs were produced by extrusion of the supporting anode composed by GDC10 and Cu oxides. A 10 μm thin GDC10 electrolytic layer and the LSF20:GDC10 cathode were deposited by dip-coating and the complete cell was co-sintered in one step. Thanks to the optimization of the composition and the employment of Li2O as sintering aid, the densification of the electrolyte was accomplished more than 500°C below the sintering temperature of GDC10. The cell had a maximum OCV of 0.54 V and the highest measured power density was 8.98 mW cm-2 with a peak power density projected to be 27.5 mW cm-2
Energy-Efficient Medium Access Control Protocols and Network Coding in Green Wireless Networks
No full textWireless networks are a popular means of communications in daily social and business activities of many users nowadays. However, current estimates indicate that wireless networks are expected to significantly contribute to the rapidly increasing energy consumption and carbon emissions of the Information and Communication Technologies (ICT) sector. Crucial factors leading to this trend are the continuous growth of wireless network infrastructure coupled with the increased number of user wireless devices equipped with various radio interfaces and batteries of extremely limited capacity (e.g., smartphones). The serious problem of energy consumption in wireless networks is mainly related to the current standard designs of wireless technologies. These approaches are based on a stack of protocol layers aiming to maximize performance-related metrics, such as throughput or Quality of Service (QoS), while paying less attention to energy efficiency. Although the focus has shifted to energy efficiency recently, most of the existing wireless solutions achieve energy savings at the cost of some performance degradation.This thesis aims at contributing to the evolution of green wireless networks by exploring new approaches for energy saving at the Medium Access Control (MAC) protocol layer and the combination of these with the integration of the Network Coding (NC) paradigm into the wireless network protocol stack for further energy savings. The main contributions of the thesis are divided into two main parts. The first part of the thesis is focused on the design and performance analysis and evaluation of novel energy-efficient distributed and centralized MAC protocols for Wireless Local Area Networks (WLANs). The second part of the thesis turns the focus to the design and performance analysis and evaluation of new NC-aware energy- efficient MAC protocols for wireless ad hoc networks. The key idea of the proposed mechanisms is to enable multiple data exchanges (with or without NC data) among wireless devices and allow them to dynamically turn on and off their radio transceivers (i.e., duty cycling) during periods of no transmission and reception (i.e., when they are listening or overhearing). Validation through analysis, computer-based simulation, and experimentation in real hardware shows that the proposed MAC solutions can significantly improve both the throughput and energy efficiency of wireless networks, compared to the existing mechanisms of the IEEE 802.11 Standard when alone or combined with the NC approach. Furthermore, the results presented in this dissertation help understand the impact of the on/off transitions of radio transceivers on the energy efficiency of MAC protocols based on duty cycling. These radio transitions are shown to be critical when the available time for sleeping is comparable to the duration of the on/off radio transitions
Development of Cobalt based Nanocatalysts for Energy and Environment
No full textThere is a rising concern about energy and environment for future. Transition from current fossil fuels to green fuels and building of cleaner environment to lead sustainable life is at enormous task. Hydrogen gas is recognized as a clean fuel and may be a sustainable solution. Hydrogen can be directly used as clean fuel in fuel cells with no harmful by-products. Chemical hydrides with high hydrogen storage capacity in terms of gravimetric and volumetric efficiencies are the most promising candidates to supply pure hydrogen at room temperature. Among them, Ammonia Borane (NH3BH3, AB) and Sodium borohydride (NaBH4, SBH) have drawn a lot of interest as they are stable, non-flammable, and nontoxic. Large amount of pure hydrogen gas is released during the hydrolysis of these hydrides in presence of certain catalysts and the by-products are non-toxic, environmentally safe and can be recycled. Co based catalysts are considered as good candidates for catalyzed hydrolysis owing to their good catalytic activity, low cost and effortless synthesis. In favor of environmental concern, especially the air pollution (conversion of CO to CO2) and water pollutions (organic pollutants) are vital problems and there is a serious need to mitigate these problems. Cobalt (Co) based materials are with high catalytic activity for hydrolysis, organic pollutants degradation and CO oxidation. So, a single Co based catalysts as powders and as immobilized coatings prepared by chemical reduction method and pulsed laser deposition (PLD) were studied for hydrogen production by hydrolysis of AB and SBH and thin film coatings Co3O4 were studied for CO oxidation and organic pollutants degradation. On the basis of characterization results, the role of catalyst to enhance catalytic activity is discussed in hydrolysis, CO oxidation and pollutants degradation reactions. The stability and re-usability of these catalysts have also been investigated
Environmentally friendly baths for Cu-Sn co-electrodeposition: cyanide-free aqueous bath and deep eutectic solvents
Get PDFThis thesis describes the work of my Ph.D studies in Industrial Engineering during past three years. It regards preparation of copper-tin alloys from green solvents for decorative purposes. Actual industrial process involves cyanide based complex bath in order to produce white bronze layers and they often contain lead as brightener and whitener. The aim of the thesis is to develop a more environmental friendly process for white bronze electrodeposition. Two different electrolytes were considered as eligible candidates: one involves a simple organic acid aqueous solution as bulk electrolyte, and the other one is a new deep eutectic solvent bath.
The investigation of electrodeposition using methanesulfonic acid as complexing agent considered a commercial bath and its optimization in order to be used in the decorative industry. The focus of the study was on the optimization of deposition parameters and verification of bath and deposit stability which was very important from industrial point of view. Obvious improvements on deposits quality and bath stability can be realized by replacement on anode material and utilization of pulse current.
Contrary to that, research on electrodeposition from deep eutectic system was quite new and few relevant studies can be referred especially in the field of alloys. As a result, this work started from deposition of single metal for better understanding of behaviors of mixtures between choline chloride and ethylene glycol or urea. Successful deposition of copper-tin alloys can be carried out under warmed conditions and variation on film composition can be controlled by changing concentrations of metallic salts in the bath. Pulse current acted as an effective tool to refine microstructure of deposits in a similar way as in aqueous solvents. Since no brightener was added, reduced luster was observed here and working mechanism of additives was found to be rather different from that in conventional baths. In summary, operation parameters including temperature, salt concentration, anode material and supporting electrolytes influence the resultant properties of deposits in great extent. Deposit quality from both solvents can be improved by using pulse current with proper frequency
Stato di eccezione, istanze securitarie e diritto penale
No full textIl presente lavoro si propone di approfondire il tema del rapporto tra sicurezza e diritto penale nelle situazioni di emergenza, attraverso l’analisi del terrorismo internazionale, utilizzato come case study.
La disamina prende le mosse dallo stato di eccezione e dai meccanismi di “controllo” dell’emergenza interni al sistema giuridico, con il richiamo a quattro diverse fasi: l’individuazione del fatto emergenziale, la valutazione sulla instaurazione di un regime eccezionale, l’emanazione della disciplina derogatoria e l’imposizione dei relativi limiti.
A sostegno della tesi per cui anche le situazioni di crisi di uno Stato debbono essere sottoposte ad una regolamentazione basata sul rispetto di diritti e principi inderogabili, viene presa in esame la disciplina delle c.d. “clausole di eccezione” presenti in alcune Convenzioni internazionali a tutela dei diritti fondamentali e le indicazioni fornite da due reports internazionali. A tale approccio teorico, si fa seguire una analisi della situazione riscontrata nella prassi, anche in riferimento all’utilizzo della teoria del margine nazionale di apprezzamento da parte della Corte europea dei diritti dell’uomo.
La trattazione si concentra poi sull’analisi degli strumenti di contrasto al terrorismo nel sistema israeliano, tenendo conto dell’approccio composito al fenomeno da esso adottato. Dopo l’esposizione del panorama costituzionale e normativo legato all’emergenza, vengono prese in esame le più importanti decisioni della Corte Suprema relative, in particolare, al problema del bilanciamento tra sicurezza e diritti umani, attraverso un’analisi della giurisprudenza in materia di omicidi mirati, presunzioni di pericolosità e metodi di interrogatorio.
Vengono inoltre affrontati i problemi connessi alla sovrapposizione tra diritto umanitario e diritti umani nella valutazione della legittimità di misure anti-terrorismo particolarmente invasive per questi ultimi, mettendo in luce i rischi legati alla possibile primazia delle istanze securitarie in un quadro di contrasto di natura bellica. Attraverso tale argomento si cerca di dimostrare la correttezza della impostazione europea, che conduce il “terrorismo” fra i fenomeni di natura criminale.
L’esperienza dell’Unione europea viene utilizzata per l’analisi del rapporto tra sicurezza e diritto penale, alla luce delle nuove competenze introdotte dal Trattato di Lisbona e alle esigenze di armonizzazione nei settori indicati dall’art. 83 TFUE. In relazione a queste ultime viene messo in evidenza il ruolo fondamentale del principio di proporzione quale canone di politica criminale, nella formulazione delle incriminazioni minime di futuro conio, e quale importante criterio ermeneutico per la Corte di giustizia e per i giudici nazionali.
Da ultimo, viene approfondito il tema della sicurezza nazionale intesa da un lato, come diritto fondamentale autonomo e di natura relativa e, dall’altro lato, come possibile interesse meritevole di tutela, da utilizzare in ambito europeo per l’armonizzazione del diritto penale sostanziale nel settore del terrorismo e per la facilitazione della cooperazione giudiziaria
Risk and Mental Element.An Analysis of National and International Law on Core Crimes.
No full textThe present analysis deals with the question of whether and to what extent mental attitudes that, at the level of cognition, do not attain the factual threshold of awareness of the criminal outcome as a practical certainty can lead to the establishment of criminal responsibility for the so-called core crimes, i.e. genocide, crimes against humanity and war crimes.The answer to this issue depends on whether and how far a given system of criminal law views the mental element applicable to the offences in question as encompassing forms of risk-taking. Seeking to comprehensively investigate the current legal situation, the present study examines the types of mental element applicable under two domestic legislations on core crimes, namely the German Völkerstrafgesetzbuch and the U.S. Federal Criminal Code, on the one hand, and in customary international law and under the ICC Statute, on the other hand. The survey turns then to whether in any of the legal systems at stake a standard of mental element has been consolidated such that it would be generally applicable unless otherwise provided. It also explores the extent to which mental attitudes departing from the threshold of awareness of the criminal outcome as a practical certainty may establish criminal responsibility for specific crimes and modes of liability. The rules thereby identified are applied to model cases describing various situations where an individual accomplishes an act of relevance to the criminal law but does not clearly perceive the consequence that will ensue from her behaviour.From the present study it emerges that there appear to exist more divergences than commonalities in the current legal landscape, regarding whether and to what extent the sphere of criminal responsibility for core crimes may be linked to attitudes of risk-taking. This outcome seems to derive first and foremost from the differing definitions of intent as they have developed in the regulatory frameworks analysed in this work. The conscious adoption of a behaviour that might lead to the realisation of an offence that is not aimed at, can under certain conditions be covered by the notion of intent found in German criminal law and in the jurisprudence of the ICTY and ICTR applying customary international law. On the other hand, it is excluded from the definition of the intent in U.S. federal criminal law and in the ICC Statute. Furthermore, in all the legal systems considered in the present study, there exist significant exceptions to the application of intent, both widening and narrowing the scope of criminal responsibility.
Considering that in a decentralized system of international justice the intervention of the ICC should be an extrema ratio, the present analysis suggests establishing a regulation to be applied by the International Criminal Court on the mental element, which reflects the gravity of cases this tribunal is called upon to adjudicate. At the same time lesser degrees of mens rea would remain applicable under national laws on core crimes
Models and systems for managing sensor and crowd-oriented processes
No full textBusiness process modeling refers to the design of business process models, using business processes languages, to orchestrate the work executed by employees, their interaction with external entities, and work items that are necessary to achieve a predefined goal.
Model-driven development allows people, generally called modelers, to design also sophisticated application logic using high-level abstractions.
Process modeling is typically connected with business, hence, existing process languages focus principally on the support and orchestration of activities executed by employees, or by external entities like web services.
However, there is a wide range of other application logics that are process-driven and that can benefit from high-level abstractions to model low-level details.
Our initial research focuses on distributed UIs, which are a distributed type of actors, and then particularly concentrated on Wireless Sensor Networks (WSNs) and crowdsourcing, which are distributed and also autonomous types of actors (they can execute a part of an application logic in an autonomous and isolated fashion).
Developing applications in these areas requires a deep knowledge of the field and a non-trivial programming effort; domain experts have to code an orchestrate the logic executed by these actors.
Since these applications are highly process-driven, domain experts could take advantage of high-level, process-oriented modeling conventions to design the internal logic of these kinds of applications.
However, the intrinsic complexity of these domains and the current state of the art of modeling paradigms make the design and execution of processes for these new actors challenging.
In this dissertation we analyze, design, and present modeling formalism and systems for managing processes in these contexts.
We tackle the challenges of the three areas with an approach that analyzes and extends existing process modeling languages, to enable the design of the processes, and with an architecture, similar for the three focuses, to support the development and execution of processes.
Starting from our initial work on the orchestration of distributed UIs, for which we present a modeling language with a set of modeling constructs specific for the UIs, we then present our contribution to WSNs and crowdsourcing domains, which are: a modeling convention for the development of WSN applications, with high-level modeling constructs that abstract the low-level details of the networks; and a modeling paradigm to design processes that are partially executed by a crowd of people.
These languages are all equipped with prototypes that contain a modeling tool to design processes and a runtime environment to support the execution.
The impact of this work is not only to the domains we focused on but also to the business process domain as we demonstrate how a process modeling is a flexible and suitable formalism to design processes with very diverging, domain-specific requirements
Addressing equity in sustainability assessment: A theoretical framework with applications in the Oil & Gas sector
Get PDFThis thesis explores the concept of equity and proposes methods to make it operational in decision-making focused on promoting sustainability. The conceptual approach developed in the research draws on the recognition that the two notions of equity and sustainability are tightly intertwined in the sustainable development debate. As George (1999) claimed, sustainable development is founded on and fully embodied by intra-generational and inter-generational equity, which might be described as transactions of rights between and across generations, respectively. In spite of this, the implications on equity are still poorly addressed in strategic decisions.
This led to the identification of the three main objectives of this research.
The first objective is to understand the extent to which sustainability issues are addressed in current practice, focusing on Strategic Environmental Assessment (SEA) experiences of spatial planning and Oil & Gas development. To this purpose, a framework is developed to analyse the degree of consideration of sustainability principles in SEA, and demonstrate its application to a sample of SEA of Italian urban plans. This framework links Gibson's (2006) sustainability principles to a number of guidance criteria and eventually to review questions, giving particular emphasis to the key concepts of intra- and inter-generational equity. The framework was applied to review the Environmental Report of a sample of urban plans of major Italian cities. The results of this review shows that, even if sustainability is commonly considered as a pivotal concept, there is still work to be done in order to effectively integrate sustainability principles into SEA. Regarding the proposed framework, the review confirms the significance of clarifying equity concerns in the light of sustainability in view of operationalizing intra- and inter-generational equity in decision-making.
The second objective is to identify criteria and indicators to measure intra- and inter-generational equity, against which present state and future trends can be assessed. A conceptual framework for identifying the different implications related to the use of different values and perceptions on equity is built. Subsequently, a set of equity perspectives to guide the assessment of strategic actions through the lens of intra- and inter-generational equity is proposed and discussed. This set includes four equity perspectives, compatible with each other with covered significant sustainability issues, and minimizing conflict, namely opportunity, distributional fairness, distributional fairness across generations and justice for an imperfect world.
The review of equity perspectives allows identifying a set of equity criteria that might be useful in focusing assessment on crucial and integrative sustainability issues. These criteria are reasonably inclusive of essential general intra- and inter-generational equity considerations that account for sustainability over space and time.
However, criteria need to be specific to the context of analysis. This is addressed in this study by selecting a specific sector of investigation that offered significant insights for dealing with sustainability in decision-making. The attention was directed to the Oil & Gas sector for the scope of challenges and positive chances posed to sustainability. For this purpose, the research work specifically fleshes out how current SEA of Oil & Gas sector practice addresses sustainability.
A framework for reviewing SEA practice helped to explore to what extent current SEA for the Oil & Gas sector contributes, procedurally and substantively, to sustainability oriented decisions. 11 case studies related to both off-shore and on-shore Oil & Gas developments are reviewed against this framework. The results show that case studies were more oriented to analyse opportunities derived from Oil & Gas development without fleshing out other potential developmental alternatives. Additionally, even if the SEA reports claim to pursuit a common strategic intent to equally share benefit derived from Oil & Gas development, they do not generally provide a means to tackle this aspect. This part of the investigation allowed also to support the identification and selection of aspects, elements, suggestions and best practise that would assist in defining contest-specific equity criteria and indicators for decision-making in the Oil & Gas sector.
This leads to the third objective of the thesis: testing the applicability of the proposed methods to a case study, dealing with complex decisions at strategic level. A case study on Oil & Gas development in the Basilicata region (Southern Italy) was selected: the Val d’Agri oil field, Western Europe’s biggest onshore oil field. Scenario storylines, representing interactions among environmental, social and economic concerns, are constructed and applied against the framework. Specifically, short-term and medium-long term scenarios are developed by varying geographical scopes, ranging from the regional scale to two nested local areas surrounding the Oil & Gas activities.
Scenarios are then assessed against the set of intra- and inter-generational criteria identified by selecting appropriate indicators adapted to context and available data. Indicators are valued according to a quali-quantitative analysis that assisted in examining and comparing trade-off between human and environmental systems under the different scenarios.
The results helped to identify opportunity and risk of different scenarios at strategic level. None of the scenarios provided “the best solution” in term of aggregated equity scores or perfect win-win solutions for each equity perspective. In the long-term, none of the territorial levels (local and regional) seemed to acquire significant increase in equity benefits, not even one at expenses of each other. According to the assumptions, this might suggest that incremental benefits of Oil & Gas development are concentrated outside the three level considered. Nevertheless, the case study shows that approaching to decision with more attention to a sustainable management of the environment and involving institutions at different levels might be a key role in achieving more wide-spread and long-term positive results.
However, scenarios presented possible significant trends in equity criteria, which were affected by restraints in data collected, as well as, simplifications and approximations in analysis. In this exercise, it was assumed that all equity criteria within each temporal dimension receive equal weights and that all three geographical levels were equally weighted too. Introducing participatory mechanisms might be useful for supporting interpretations of implications potentially affecting generations at different temporal and territorial scale, satisfying possible needs of other equity criteria, and establishing priorities in perspectives on equity adopted. In this sense, the equity framework proposed might be a suitable tool for supporting and guiding deliberative processes. Analogously, the spatio-temporal decision matrix, framed through the lens of equity for assessing scenarios against equity criteria, might represent a simple yet flexible framework for analysing and discussing concurrently temporal and spatial implications of plausible storylines
Analysis and Protection of SIP based Services
No full textMultimedia communications over IP are booming as they offer higher flexibility and more features than traditional voice and video services.
IP telephony known as Voice over IP (VoIP) is one of the commercially most important emerging trends in multimedia communications over IP. Due to the flexibility and descriptive power, the Session Initiation Protocol (SIP) is becoming the root of many sessions-based applications such as VoIP and media streaming that are used by a growing number of users and organizations. The increase of the availability and use of such applications calls for careful attention to the possibility of transferring malformed, incorrect, or malicious SIP messages as they can cause problems ranging from relatively innocuous disturbances to full blown attacks and frauds. Given this scenario, a deep knowledge of the normal behavior of the network and users is essential to problem diagnosis and security protection of IP Telephony. Moreover, analysis tools taking into account service semantics and troubleshooting VoIP systems based on SIP are of paramount importance for network administrators. However, efficient design and deployment of robust and high performance security controlling systems remain a high challenge, in particular due to the open architecture of the Internet, heterogeneous environment and real time communication constraint. This thesis deals with the analysis and protection of services based on the SIP protocol with a special focus on SIP based VoIP applications. The first part of the work is dedicated to the conformance and security analysis of SIP based VoIP services.
To this end, our first endeavor is to define a formal conceptual model of VoIP threat domain with the aim to exchange a common vocabulary about the security related information of the domain. We have introduced an ontology defined as “VoIP-Onto" that provides a formal representation of a comprehensive taxonomy of VoIP attacks followed by specific security recommendations and guidelines for protecting the underlying infrastructure from these attacks. The use of “VoIP-Onto" is not only limited to as a general vocabulary and extensible dictionary for sharing domain knowledge about VoIP security, but also can be employed in a real environment for testing or intrusion detection purposes.
We have also concentrated on designing synthetic traffic generators considering the difficulties and challenges of collecting real-world VoIP traffic for the purpose of testing monitoring and security controlling tools. To this end, we have introduced “VoIPTG", a generic synthetic traffic generator, that provides flexibility and efficiency in generation of large amount of synthetic VoIP traffic by imitating the realistic behavior profiles for users and attackers. We have also implemented “SIP-Msg-Gen", a SIP fuzzer, capable to generate both the well-formed and fuzzed SIP messages with ease.
Then, we focus on designing an on-line filter able to examine the stream
of incoming SIP messages and classifies them as “good" or “bad" depending on whether their structure and content are deemed acceptable or not. Because of the different structure, contents and timing of the SIP “bad" messages, their filtering is best carried out by a multistage classifier consisting of deterministic lexical analyzer and supervised machine learning classifiers. The performance and efficiency of our proposed multi-stage filtering system is tested with a large set of SIP based VoIP traffic including both the real and synthetic traces. The experimental result of the filtering system is very promising with high accuracy providing fast attack detection.
Next, the focus is shifted on the understanding and modeling the social interaction patterns of users of the VoIP domain. The notion of “social
networks" is applied in the context of SIP based VoIP network, where “social networks" of VoIP users are built based on their telephone records.
Then, Social Network Analysis (SNA) techniques are applied on these “social networks" of VoIP users to explore their social behavioral patterns.
A prototype of filtering system for SIP based VoIP services is also implemented to demonstrate that the knowledge about the social behavior of the VoIP users is helpful in problem diagnosis, intruders detection, and security protection. The filtering system is trained with the normal behavioral patterns of the users. The machine, thus trained, is capable of identifying “malicious" users