Security analysis of a machine-to-machine messaging system

With the increasing popularity of small embedded devices, self-organizing and self-repairing networks are preferable. One such choice are peer-to-peer (P2P) systems which create an overlay network in the application layer to achieve a de-centralized and resilient communication system. Neuropil builds an encryption layer on top of a Pastry/Tapestry P2P network to provide confidentiality and integrity to a certain degree. This thesis analyzes the protocol used by Neuropil in its default implementation and explores some possibilities to improve the security

Networks with small stretch number

Abstract In a previous work, the authors introduced the class of graphs with bounded induced distance of order k (BID(k) for short), to model non-reliable interconnection networks. A network modeled as a graph in BID(k) can be characterized as follows: if some nodes have failed, as long as two nodes remain connected, the distance between these nodes in the faulty graph is at most k times the distance in the non-faulty graph. The smallest k such that G∈BID(k) is called stretch number of G. We show an odd characteristic of the stretch numbers: every rational number greater or equal 2 is a stretch number, but only discrete values are admissible for smaller stretch numbers. Moreover, we give a new characterization of classes BID(2−1/i), i⩾1, based on forbidden induced subgraphs. By using this characterization, we provide a polynomial time recognition algorithm for graphs belonging to these classes, while the general recognition problem is Co-NP-complete

Polysaccharide-Based In Situ Self-Healing Hydrogels for Tissue Engineering Applications

In situ hydrogels have attracted increasing interest in recent years due to the need to develop effective and practical implantable platforms. Traditional hydrogels require surgical interventions to be implanted and are far from providing personalized medicine applications. However, in situ hydrogels offer a wide variety of advantages, such as a non-invasive nature due to their localized action or the ability to perfectly adapt to the place to be replaced regardless the size, shape or irregularities. In recent years, research has particularly focused on in situ hydrogels based on natural polysaccharides due to their promising properties such as biocompatibility, biodegradability and their ability to self-repair. This last property inspired in nature gives them the possibility of maintaining their integrity even after damage, owing to specific physical interactions or dynamic covalent bonds that provide reversible linkages. In this review, the different self-healing mechanisms, as well as the latest research on in situ self-healing hydrogels, is presented, together with the potential applications of these materials in tissue regeneration.This research was funded by the Spanish State Research Agency (AEI) and the European Regional Development Fund (ERFD) through the project PID2019-106099RB-C43/AEI/10.13039/501100011033. Spanish Ministry of Economy and Competitiveness (MINECO) through the project MAT2016-76039-C4-3-R (AEI/FEDER, UE) and from the Basque Government Industry and Education Department under the ELKARTEK (KK-2020/00068, KK-2020/00099, KK2019/00039 and KK2019/00101), HAZITEK and PIBA (PIBA-2018-06) programs, respectively

Self-Repairable Polymeric Networks: Synthesis and Network Design

This dissertation describes the design, synthesis and development of a new class of polymeric networks that exhibit self-repairing properties under UV exposure. It consists of two parts: (a) modification and synthesis of oxetane (OXE), and oxolane (OXO) substituted chitosan (CHI) macromonomer, and (b) design, and synthesis of self-repairing polyurethane (PUR) networks consisting of modified chitosan. Unmodified CHI consisting of acetamide (-NHCOCH3), primary hydroxyl (-OH), and amine (-NH2) functional groups were reacted with OXE or OXO compounds under basic conditions in order to substitute the 1° –OH groups, and at the same time, convert -NHCOCH3 functionalities into -NH2 groups, while maintaining their un-reacted form to generate OXE/OXO-substituted CHI macromonomer. These substituted CHI macromonomers were incorporated within the PUR backbone by reacting with trifunctional isocyanate in the presence of polyethylene glycol (PEG) and dibutyl tin dilaurate catalyst (DBTDL). Utilizing spectroscopic analysis combined with optical microscopy, these studies showed that the kinetics of self-repair depends on the stoichiometry of the individual entities as well as the time required for self-repairing to occur decrease with increasing OXE quantity within the network. Internal reflection infrared imaging (IRIRI) of OXE/OXO-CHI-PUR networks as well as Raman and Fourier transform IR (FT-IR) studies of OXE/OXO-CHI macromonomers revealed that cationic OXE/OXO ring opening, free radical polyurea (PUA)-to-PUR conversion, along with chair-to-boat conformational changes of CHI backbone are responsible for repairing the damaged network. The network remodeling process, investigated by utilizing micro-thermal analyzer (μTA), revealed that mechanical damage generates small fragments or oligomers within the scratch, therefore glass transition temperature (Tg) decreases, and under UV exposure cross-linking reactions propagate from the bottom of the scratch to the top resulting in an increase of Tg within the scratch and subsequently repair

Self-spanner graphs

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( k , +)-distance-hereditary graphs

AbstractIn this work we introduce, characterize, and provide algorithmic results for (k,+)-distance-hereditary graphs, k⩾0. These graphs can be used to model interconnection networks with desirable connectivity properties; a network modeled as a (k,+)-distance-hereditary graph can be characterized as follows: if some nodes have failed, as long as two nodes remain connected, the distance between these nodes in the faulty graph is bounded by the distance in the non-faulty graph plus an integer constant k. The class of all these graphs is denoted by DH(k,+). By varying the parameter k, classes DH(k,+) include all graphs and form a hierarchy that represents a parametric extension of the well-known class of distance-hereditary graphs

Internet of Things Strategic Research Roadmap

Internet of Things (IoT) is an integrated part of Future Internet including existing and evolving Internet and network developments and could be conceptually defined as a dynamic global network infrastructure with self configuring capabilities based on standard and interoperable communication protocols where physical and virtual “things” have identities, physical attributes, and virtual personalities, use intelligent interfaces, and are seamlessly integrated into the information network

Improving reuse of semiconductor equipment through benchmarking, standardization, and automation

Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering; in conjunction with the Leaders for Manufacturing Program at MIT, 2006.Includes bibliographical references (p. 91-92).The 6D program at Intel® Corporation was set up to improve operations around capital equipment reuse, primarily in their semiconductor manufacturing facilities. The company was faced with a number of challenges, including differing work flows across multiple locations, lack of centralized work flow management, discontinuous inventory information, and other opportunities for cost reduction. The internship was set up to benchmark and explore potential for integration of best known methods, accumulated both inside and outside the company. Based on interviews, research and quantitative analysis, opportunities were identified for reuse of equipment shipping crates, improvement in warehouse inventory management, and changes in labor models to facilitate better knowledge capture and dissemination. As a result of this study Intel® Corporation may realize significant improvement in the areas mentioned in terms of cost reduction, process improvement and knowledge management. By using a flexible approach to problem identification and generating organizational interest in the improvements, recommendations were well received and should lead to eventual adoption.by Jacob Silber.S.M.M.B.A