253 research outputs found
The State-of-the-Art Questionnaire on Applied Systems Analysis: A Report on the Responses
This publication is the second report by the Survey Project on the structure and content of a proposed Series of monographs and a Handbook to survey the state-of-the-art of applied systems analysis. In the first report (RR-76-16, Systems Analysis: An Outline for the State-of-the-Art Survey Publications, July 1976), we presented a revised outline and current guidelines for the Survey Project publication program; in the present document, the sequel. we discuss the response to a questionnaire -- distributed widely throughout the systems analyst community -- upon which our revised outline is based.
This report should be of interest to the questionnaire respondents, and to a wider audience as well. in that it reflects what some 160 analysts and others associated with systems analysis think about systems analysis, what they consider to be vital and important in this area, and what they think to be peripheral or of minor relevance
Systems Analysis: An Outline for the State-of-the-Art Survey Publications
IIASA plans to organize, commission, and publish a Series of volumes and a Handbook to survey the international state-of-the-art of applied systems analysis. This report provides the Survey Project's explication of the concept of applied systems analysis; it describes in detail the proposed Series and Handbook, including purpose, audience, international character, level of presentation, authors, reviewers, and remuneration policies. An outline spanning the field of interest of applied systems analysis is designed to help prospective authors with the choice of topics. Guidelines are provided for the acceptability of volumes for the Series, and suggestions for prospective authors on the preparation of prospectuses (outlines) for Series monographs are included. These prospectuses are submitted to the Editorial Board and special liaison committees established in each of IIASA's National Member Organizations. A summary checklist of procedures for development of Series volumes is provided in the Appendix
Composability in quantum cryptography
In this article, we review several aspects of composability in the context of
quantum cryptography. The first part is devoted to key distribution. We discuss
the security criteria that a quantum key distribution protocol must fulfill to
allow its safe use within a larger security application (e.g., for secure
message transmission). To illustrate the practical use of composability, we
show how to generate a continuous key stream by sequentially composing rounds
of a quantum key distribution protocol. In a second part, we take a more
general point of view, which is necessary for the study of cryptographic
situations involving, for example, mutually distrustful parties. We explain the
universal composability framework and state the composition theorem which
guarantees that secure protocols can securely be composed to larger
applicationsComment: 18 pages, 2 figure
Attacks on quantum key distribution protocols that employ non-ITS authentication
We demonstrate how adversaries with unbounded computing resources can break
Quantum Key Distribution (QKD) protocols which employ a particular message
authentication code suggested previously. This authentication code, featuring
low key consumption, is not Information-Theoretically Secure (ITS) since for
each message the eavesdropper has intercepted she is able to send a different
message from a set of messages that she can calculate by finding collisions of
a cryptographic hash function. However, when this authentication code was
introduced it was shown to prevent straightforward Man-In-The-Middle (MITM)
attacks against QKD protocols.
In this paper, we prove that the set of messages that collide with any given
message under this authentication code contains with high probability a message
that has small Hamming distance to any other given message. Based on this fact
we present extended MITM attacks against different versions of BB84 QKD
protocols using the addressed authentication code; for three protocols we
describe every single action taken by the adversary. For all protocols the
adversary can obtain complete knowledge of the key, and for most protocols her
success probability in doing so approaches unity.
Since the attacks work against all authentication methods which allow to
calculate colliding messages, the underlying building blocks of the presented
attacks expose the potential pitfalls arising as a consequence of non-ITS
authentication in QKD-postprocessing. We propose countermeasures, increasing
the eavesdroppers demand for computational power, and also prove necessary and
sufficient conditions for upgrading the discussed authentication code to the
ITS level.Comment: 34 page
Impact Ionization in ZnS
The impact ionization rate and its orientation dependence in k space is
calculated for ZnS. The numerical results indicate a strong correlation to the
band structure. The use of a q-dependent screening function for the Coulomb
interaction between conduction and valence electrons is found to be essential.
A simple fit formula is presented for easy calculation of the energy dependent
transition rate.Comment: 9 pages LaTeX file, 3 EPS-figures (use psfig.sty), accepted for
publication in PRB as brief Report (LaTeX source replaces raw-postscript
file
A novel characterisation approach to reveal the mechano–chemical effects of oxidation and dynamic distension on polypropylene surgical mesh
Polypropylene (PP) surgical mesh, used successfully for the surgical repair of abdominal hernias, is associated with serious clinical complications when used in the pelvic floor for repair of stress urinary incontinence or support of pelvic organ prolapse. While manufacturers claim that the material is inert and non-degradable, there is a growing body of evidence that asserts PP fibres are subject to oxidative damage and indeed explanted material from patients suffering with clinical complications has shown some evidence of fibre cracking and oxidation. It has been proposed that a pathological cellular response to the surgical mesh contributes to the medical complications; however, the mechanisms that trigger the specific host response against the material are not well understood. Specifically, this study was constructed to investigate the mechano–chemical effects of oxidation and dynamic distension on polypropylene surgical mesh. To do this we used a novel advanced spectroscopical characterisation technique, secondary electron hyperspectral imaging (SEHI), which is based on the collection of secondary electron emission spectra in a scanning electron microscope (SEM) to reveal mechanical–chemical reactions within PP meshes
Tight Finite-Key Analysis for Quantum Cryptography
Despite enormous progress both in theoretical and experimental quantum
cryptography, the security of most current implementations of quantum key
distribution is still not established rigorously. One of the main problems is
that the security of the final key is highly dependent on the number, M, of
signals exchanged between the legitimate parties. While, in any practical
implementation, M is limited by the available resources, existing security
proofs are often only valid asymptotically for unrealistically large values of
M. Here, we demonstrate that this gap between theory and practice can be
overcome using a recently developed proof technique based on the uncertainty
relation for smooth entropies. Specifically, we consider a family of
Bennett-Brassard 1984 quantum key distribution protocols and show that security
against general attacks can be guaranteed already for moderate values of M.Comment: 11 pages, 2 figure
Recommended from our members
Preparation, analysis, and application of coated glass targets for the Wendelstein 7-X laser blow-off system
Coated glass targets are a key component of the Wendelstein 7-X laser blow-off system that is used for impurity transport studies. The preparation and analysis of these glass targets as well as their performance is examined in this paper. The glass targets have a high laser damage threshold and are coated via physical vapor deposition with μm thick films. In addition, nm-thin layers of Ti are used as an interface layer for improved ablation efficiency and reduced coating stress. Hence, the metallic or ceramic coating has a lateral homogeneity within 2% and contaminants less than 5%, being optimal for laser ablation processing. With this method, a short (few ms) and well defined pulse of impurities with about 1017 particles can be injected close to the last closed flux surface of Wendelstein 7-X. In particular, a significant amount of atoms with a velocity of about 1 km/s enters the plasma within 1 ms. The atoms are followed by a negligible concentration of slower clusters and macro-particles. This qualifies the use of the targets and applied laser settings for impurity transport studies with the laser blow-off system in Wendelstein 7-X. © 2020 Author(s)
Tetrakis(trimethylsilyloxy)silane for nanostructured SiO2-like films deposited by PECVD at atmospheric pressure
We performed the thin films deposition using atmospheric pressure plasma enhanced chemical vapour deposition (AP-PECVD) by means of a radiofrequency and a microwave plasma jets operating with mixtures of argon and tetrakis(trimethylsilyloxy)silane (TTMS)
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