Microstructure of intermetallic particle strengthened high-chromium fully ferritic steels

An improvement of power plant efficiency necessitates an increase of the process parameters and thus enables a reduction of consumed primary resources. Furthermore more efficient, sustainable, flexible and cost-effective energy technologies are strongly needed. For this reason the current research concentrates on a new concept of high-chromium fully ferritic stainless steels which are strengthened by a combination of solid-solution and intermetallic Laves phase particles. Such steels exhibit favourable creep, thermomechanical fatigue and steam oxidation behaviour up to 650°C. Based on detailed analysis by high-resolution scanning and transmission electron microscopy the particle size evolution and compositions were studied. Variations in chemical compositions were analysed experimentally and compared with thermodynamic equilibrium composition modelling results.

This paper is part of a thematic issue on the 9th International Charles Parsons Turbine and Generator Conference. All papers have been revised and extended before publication in Materials Science and Technology.     

The Proto-Ribosome: An Ancient Nano-machine for Peptide Bond Formation

The ribosome is a ribozyme whose active site, the peptidyl transferase center (PTC), is situated within a highly conserved universal symmetrical region that connects all ribosomal functional centers involved in amino acid polymerization. The linkage between this elaborate architecture and A-site tRNA position revealed that the A- to P-site passage of the tRNA 3′ terminus during protein synthesis is performed by a rotary motion, synchronized with the overall tRNA/mRNA sideways movement, and guided by the PTC. This rotary motion leads to suitable stereochemistry for peptide bond formation as well as for substrate-mediated catalysis. Analysis of the substrate binding modes to ribosomes led to the hypothesis that the ancient ribosome produced single peptide bonds and non-coded chains, potentially in a similar manner to the modern PTC. Later in evolution, a mechanism, enabling some type of decoding genetic control triggered the emergence of the small ribosomal subunit or part of it. This seems to be the result of the appearance of reaction products that could have evolved after polypeptides capable of enzymatic function were generated sporadically, while an ancient stable RNA fold was converted into an old version of a tRNA molecule. Since in the contemporary ribosome, the symmetry relates only to the backbone fold and nucleotide orientations but not nucleotide sequences, it emphasizes the superiority of functional requirement over sequence conservation, and indicates that the PTC may have evolved by gene fusion or gene duplication.     

Physically-based models of low-power wireless links using signal power simulation

We propose deriving wireless simulation models from experimental traces of radio signal strength. Because experimental traces have holes due to packet losses, we explore two algorithms for filling the gaps in lossy experimental traces. Using completed traces, we apply the closest-fit pattern matching (CPM) algorithm, originally designed for modeling external interference, to model signal strength.We compare the observed link behavior using our models with that of the experimental packet trace. Our approach results in more accurate packet reception ratios (PRR) than current simulation methods, reducing the absolute error in PRR by up to about 0.3 in the experiments we present. We also find that using CPM for signal strength improves simulation of packet burstiness, reducing the Kantorovich–Wasserstein (KW) distance of conditional packet delivery functions (CPDFs) by a factor of about three for intermediate links. Our model reduces the factor of error in the number of parent changes in the standard TinyOS collection protocol (CTP) by an order of magnitude or more as compared to a real signal power trace in two simple test scenarios. We show that our methods are robust to the sampling frequency of the learning deployment and are thus generally applicable for simulating arbitrary applications without a pre-determined packet transmission frequency.These improvements give low-power wireless network simulators a better capability to capture real-world dynamics and edge conditions that protocol designers typically must wait until deployment to detect.     

Low humidity after harvest changes the abscission site in bunch cherry tomatoes

BACKGROUND: In bunch cherry tomatoes (BCTs) abscission of the fruit from the bunch, rather than deterioration of fruit determines the life‐span of the produce. Two abscission sites have been characterised: the joint (AJ) in the middle of the pedicel, and at the receptacle (AR) at the fruit‐pedicel interphase. The type of abscission is sensitive to growth conditions; joint abscission is typical of winter harvests whereas receptacle abscission is dominant in summer harvests. The aim of the present study was to determine the effect of relative humidity (RH) in terms of water vapour pressure deficit (WVPD) during storage and shelf life on the course and site of abscission of BCTs. RESULTS: The rachis composes only about 2% of the bunch weight, and therefore most of the water loss originated from the fruit. When the bunch lost almost 10% of its weight under low humidity, the relative weight of the rachis was reduced to one‐quarter of its original value. Storage at low WVPD resulted in dominance of AJ whereas storage at high WVPD resulted in dominance of AR. BCTs that exhibited primarily AJ after cold storage was prone to either AJ or AR in high or low shelf‐life RH, respectively. BCTs subjected to elevated temperature and high WVPD after harvest developed receptacle abscission. CONCLUSION: Dehydration of the receptacle abscission zone makes it prone to abscission and this process can be prevented by high‐RH storage. Copyright © 2009 Society of Chemical Industry     

Mercurial Commitments with Applications to Zero-Knowledge Sets

We introduce a new flavor of commitment schemes, which we call mercurial commitments. Informally, mercurial commitments are standard commitments that have been extended to allow for soft decommitment. Soft decommitments, on the one hand, are not binding but, on the other hand, cannot be in conflict with true decommitments. We then demonstrate that a particular instantiation of mercurial commitments has been implicitly used by Micali, Rabin and Kilian to construct zero-knowledge sets. (A zero-knowledge set scheme allows a Prover to (1) commit to a set S in a way that reveals nothing about S and (2) prove to a Verifier, in zero-knowledge, statements of the form x∈S and x?S.) The rather complicated construction of Micali et al. becomes easy to understand when viewed as a more general construction with mercurial commitments as an underlying building block. By providing mercurial commitments based on various assumptions, we obtain several different new zero-knowledge set constructions.     

A new method for fetal ECG detection

Presented in this work is the theoretical basis of a new method we propose for the analysis of fetal ECG (FECG). This method is intended to detect the fetal HR from a weak FECG signal, and to supply us with an average FECG complex. The FECG signals studied in this work were recorded from the maternal abdominal wall. The core of our method is the computation of a triple parametric transform, using analyzing functions which have a greater correlation with the ECG signal than the correlation of the standard sine and cosine functions used in a Fourier transform. The functions used are trains of square waves characterized by the width of the square wave, their periodicity, and some initial phase value. This method, applied here to a medical problem, can be more generally applied to handle weak quasiperiodic sharp signals of any origin.     

Reliability demonstration for safety-critical systems

This paper suggests a new model for reliability demonstration of safety-critical systems, based on the TRW Software Reliability Theory. The paper describes the model, the test equipment required, and test strategies based on the various constraints occurring during software development. The paper also compares a new testing method, single risk sequential testing (SRST), with the common probability ratio sequential testing method (PRST), and concludes that: (i) SRST provides higher chances of success than PRST; (ii) SRST takes less time to complete than PRST; and (iii) SRST satisfies the consumer-risk criterion, whereas PRST provides a much smaller consumer-risk than the requirement     

Image Morphing with Feature Preserving Texture

Image metamorphosis as an animation tool has mostly been employed in the context of the entire image. This work explores the use of isolated and focused image based metamorphosis between two-dimensional objects, while capturing the features, colors, and textures of the objects. This pinpointed approach allows one to independently overlay several such dynamic shapes, without any bleeding of one shape into another. Hence, shape blending and metamorphosis of two-dimensional objects can be exploited as animated sequences of clip arts.     

Algorithm optimization using a rule-based system. A case study: The Direct Kinematic Solution in robotics

The computation burden of intensive numerical real-time algorithms is a problem encountered in robotics and many other fields. A cost-effective solution for the implementation of these algorithms requires knowledge of computer architecture, compiler technology and algorithms. A cost-effective numeric processing methodology using a combined hardware-software approach and taking advantage of logic programming tools is presented. The methodology is based on optimizing the numerical calculation process of the algorithm. It also enables the specification of hardware resources. The process uses a rule-based-system (RBS) implemented in the logic programming language Prolog to automatically reduce the number of operations in the numerical execution of the algorithm and optimizes the use of hardware resources. The methodology provides a solution for the problems of handshake overhead and algorithm translation efficiency.The Direct Kinematics Solution (DKS), a robot arm control algorithm, is presented as a case study to illustrate the methodology. The proposed methodology has a general potential which can be extended to the optimization or implementation of different algorithms.