7,237 research outputs found
Brittle fracture down to femto-Joules - and below
We analyze large sets of energy-release data created by stress-induced
brittle fracture in a pure sapphire crystal at close to zero temperature where
stochastic fluctuations are minimal. The waiting-time distribution follows that
observed for fracture in rock and for earthquakes. Despite strong time
correlations of the events and the presence of large-event precursors, simple
prediction algorithms only succeed in a very weak probabilistic sense. We also
discuss prospects for further cryogenic experiments reaching close to
single-bond sensitivity and able to investigate the existence of a
transition-stress regime.Comment: REVTeX, new figure added, minor modifications to tex
Single-Event Upset Analysis and Protection in High Speed Circuits
The effect of single-event transients (SETs) (at a combinational node of a design) on the system reliability is becoming a big concern for ICs manufactured using advanced technologies. An SET at a node of combinational part may cause a transient pulse at the input of a flip-flop and consequently is latched in the flip-flop and generates a soft-error. When an SET conjoined with a transition at a node along a critical path of the combinational part of a design, a transient delay fault may occur at the input of a flip-flop. On the other hand, increasing pipeline depth and using low power techniques such as multi-level power supply, and multi-threshold transistor convert almost all paths in a circuit to critical ones. Thus, studying the behavior of the SET in these kinds of circuits needs special attention. This paper studies the dynamic behavior of a circuit with massive critical paths in the presence of an SET. We also propose a novel flip-flop architecture to mitigate the effects of such SETs in combinational circuits. Furthermore, the proposed architecture can tolerant a single event upset (SEU) caused by particle strike on the internal nodes of a flip-flo
The twisted open string partition function and Yukawa couplings
We use the operator formalism to derive the bosonic contribution to the
twisted open string partition function in toroidal compactifications. This
amplitude describes, for instance, the planar interaction between g+1
magnetized or intersecting D-branes. We write the result both in the closed and
in the open string channel in terms of Prym differentials on the appropriate
Riemann surface. Then we focus on the g=2 case for a 2-torus. By factorizing
the twisted partition function in the open string channel we obtain an explicit
expression for the 3-twist field correlator, which is the main ingredient in
the computation of Yukawa couplings in D-brane phenomenological models. This
provides an alternative method for computing these couplings that does not rely
on the stress-energy tensor technique.Comment: 32 pages, 5 figures, Latex; v2: typos correcte
A Systematic Approach for Evaluating Satellite Communications Systems
The aerospace environment imposes straight opera- tive conditions so every electronic system usually needs to be validated for these. The same way, communica- tion systems need to be evaluated before their intro- duction in aerospace applications. In the paper we present a new methodology for the evaluation of com- munication systems in space applications. The meth- odology aims, by abstraction, at identifying all the critical aspects for the evaluation and at defining a standard and reusable framework in order to be appli- cable to any Communication Systems. The methodol- ogy has been applied for the evaluation of three Data Bus for satellite communications: 1553, 1-Wire and Profibus DP RS 485 based systems have been analyzed and evaluate
Measurement of constant radius swept features in cultural heritage
none3The dimensional characterization of archaeological fragment is a very complex
operation and could prove to be useful for identifying the presence of standard attributes in the
ceramics found from a specific archaeological site, or for making comparisons and analysis of
similarities or for studying ancient technologies used for manufacture of objects. The
dimensional analysis of the fragments is now carried out manually with traditional measuring
devices. Typically, the results obtained are inaccurate and non-repeatable measurements.
This paper focuses on the dimensional characterization of a specific geometric class of features:
the constant radius swept features (called here CRS features). Several archaeological features,
such as rims, bases, decorative motifs, processing marks and grooves are referable from a
geometric point of view to the class of CRS features. These are detail features, which may be
very interesting for the investigation of some aspects related to the historical-archaeological
classification of the find. CRS features are often found on worn, damaged (e.g. chipped) or
fragmented objects; they are frequently characterized, from a geometric point of view, by free
form surfaces and by a limited cross sectional extension. In some cases, CRS features can be of
axially symmetrical geometry: this occurs quite frequently in the case of archaeological pottery.
For all these reasons, it is often difficult to apply traditional manual methods for the quantitative
dimensional characterization of CRS features.
This paper describes an original methodology for the measurement of CRS features acquired by
scanning technologies. The algorithmic implementation of this methodology, consisting of a
suitable processing of the feature nodes, allows to carry out automatically the dimensional
characterization of the feature.Di Angelo L., Di Stefano P., Morabito A.E.Di Angelo, L.; Di Stefano, P.; Morabito, A. E
- …