bluuebunny/crossref_metadata_2025 huggingface dataset:
HLA-A*0201-restricted CTL epitope of a novel osteosarcoma antigen, papillomavirus binding factor
Authors: Tsukahara Tomohide , Kawaguchi Satoshi , Torigoe Toshihiko , Takahashi Akari , Murase Masaki , Kano Masanobu , Wada Takuro , Kaya Mitsunori , Nagoya Satoshi , Yamashita Toshihiko , Sato Noriyuki
Published: June 2009

Background

To develop peptide-based immunotherapy for osteosarcoma, we previously identified papillomavirus binding factor (PBF) as a CTL-defined osteosarcoma antigen in the context of HLA-B55. However, clinical application of PBF-based immunotherapy requires identification of naturally presented CTL epitopes in osteosarcoma cells in the context of more common HLA molecules such as HLA-A2.

Methods

Ten peptides with the HLA-A*0201 binding motif were synthesized from the amino acid sequence of PBF according to the BIMAS score and screened with an HLA class I stabilization assay. The frequency of CTLs recognizing the selected PBF-derived peptide was determined in peripheral blood of five HLA-A*0201+patients with osteosarcoma using limiting dilution (LD)/mixed lymphocyte peptide culture (MLPC) followed by tetramer-based frequency analysis. Attempts were made to establish PBF-specific CTL clones from the tetramer-positive CTL pool by a combination of limiting dilution and single-cell sorting. The cytotoxicity of CTLs was assessed by51Cr release assay.

Results

Peptide PBF A2.2 showed the highest affinity to HLA-A*0201. CD8+ T cells reacting with the PBF A2.2 peptide were detected in three of five patients at frequencies from 2 × 10-7to 5 × 10-6. A tetramer-positive PBF A2.2-specific CTL line, 5A9, specifically lysed allogeneic osteosarcoma cell lines that expressed both PBF and either HLA-A*0201 or HLA-A*0206, autologous tumor cells, and T2 pulsed with PBF A2.2. Five of 12 tetramer-positive CTL clones also lysed allogeneic osteosarcoma cell lines expressing both PBF and either HLA-A*0201 or HLA-A*0206 and T2 pulsed with PBF A2.2.

Conclusion

These findings indicate that PBF A2.2 serves as a CTL epitope on osteosarcoma cells in the context of HLA-A*0201, and potentially, HLA-A*0206. This extends the availability of PBF-derived therapeutic peptide vaccines for patients with osteosarcoma.
Approximating Critical Parameters of Branching Random Walks
Authors: Bertacchi Daniela , Zucca Fabio
Published: June 2009

Given a branching random walk on a graph, we consider two kinds of truncations: either by inhibiting the reproduction outside a subset of vertices or by allowing at most m particles per vertex. We investigate the convergence of weak and strong critical parameters of these truncated branching random walks to the analogous parameters of the original branching random walk. As a corollary, we apply our results to the study of the strong critical parameter of a branching random walk restricted to the cluster of a Bernoulli bond percolation.
Quasi-Birth-and-Death Processes, Lattice Path Counting, and Hypergeometric Functions
Authors: van Leeuwaarden Johan S. H. , Squillante Mark S. , Winands Erik M. M.
Published: June 2009

In this paper we consider a class of quasi-birth-and-death processes for which explicit solutions can be obtained for the rate matrix R and the associated matrix G. The probabilistic interpretations of these matrices allow us to describe their elements in terms of paths on the two-dimensional lattice. Then determining explicit expressions for the matrices becomes equivalent to solving a lattice path counting problem, the solution of which is derived using path decomposition, Bernoulli excursions, and hypergeometric functions. A few applications are provided, including classical models for which we obtain some new results.
Perturbed MAP Risk Models with Dividend Barrier Strategies
Authors: Cheung Eric C. K. , Landriault David
Published: June 2009

In the context of a dividend barrier strategy (see, e.g. Lin, Willmot and Drekic (2003)) we analyze the moments of the discounted dividend payments and the expected discounted penalty function for surplus processes with claims arriving according to a Markovian arrival process (MAP). We show that a relationship similar to the dividend-penalty identity of Gerber, Lin and Yang (2006) can be established for the class of perturbed MAP surplus processes, extending in the process some results of Li and Lu (2008) for the Markov-modulated risk model. Also, we revisit the same ruin-related quantities in an identical MAP risk model with the only exception that the barrier level effective at time t depends on the state of the underlying environment at this time. Similar relationships are investigated and derived. Numerical examples are also considered.
Last Exit Before an Exponential Time for Spectrally Negative Lévy Processes
Authors: Baurdoux E. J.
Published: June 2009

Chiu and Yin (2005) found the Laplace transform of the last time a spectrally negative Lévy process, which drifts to ∞, is below some level. The main motivation for the study of this random time stems from risk theory: what is the last time the risk process, modeled by a spectrally negative Lévy process drifting to ∞, is 0? In this paper we extend the result of Chiu and Yin, and we derive the Laplace transform of the last time, before an independent, exponentially distributed time, that a spectrally negative Lévy process (without any further conditions) exceeds (upwards or downwards) or hits a certain level. As an application, we extend a result found in Doney (1991).
Strong Laws for Balanced Triangular Urns
Authors: Bose Arup , Dasgupta Amites , Maulik Krishanu
Published: June 2009

Consider an urn model whose replacement matrix is triangular, has all nonnegative entries, and the row sums are all equal to 1. We obtain strong laws for the counts of balls corresponding to each color. The scalings for these laws depend on the diagonal elements of a rearranged replacement matrix. We use these strong laws to study further behavior of certain three-color urn models.
The Integral of the Supremum Process of Brownian Motion
Authors: Janson Svante , Petersson Niclas
Published: June 2009

In this paper we study the integral of the supremum process of standard Brownian motion. We present an explicit formula for the moments of the integral (or area)(T) covered by the process in the time interval [0,T]. The Laplace transform of(T) follows as a consequence. The main proof involves a double Laplace transform of(T) and is based on excursion theory and local time for Brownian motion.
Amino acid sequence dependence of nanoscale deformation mechanisms in alpha-helical protein filaments
Authors: Bertaud J , Qin Z , Buehler M J
Published: June 2009

Alpha-helical protein filaments are the key constituent of biological materials such as cells, hair, hoof, and wool, where they assemble to form hierarchical filamentous structures. Here the focus is on the multiscale mechanical properties of this class of protein materials, where a systematic analysis is reported on the competition between protein rupture and interprotein sliding for different molecular geometries and variations in the amino acid sequence. Through this analysis, facilitated by simulations with a coarse-grained mesoscale model of alpha-helical protein domains, key molecular deformation mechanisms are identified in alpha-helical protein filaments. This study specifically focuses on elucidating the nanoscale mechanisms of strain accommodation under variation of structural and chemical parameters. The main finding is that interprotein sliding is a dominating mechanism that persists for a variety of geometries and realistic biologically occurring amino acid sequences.
Scheduling of casting in real foundries using linear programming
Authors: Yang J-M , Park Y K
Published: June 2009

This study develops a simple and convenient scheduling methodology using linear programming (LP) for three typical and distinctive production situations in real foundries: sand casting, low-pressure casting, and a combination of sand casting, low-pressure casting, and automated casting. Proposed to determine an optimal casting sequence, this methodology is successfully applied to all casting environments that produce simultaneously various types of castings with different alloys and weights in a number of orders within a predetermined period. It can also generate accurate scheduling results for maximized furnace or ingot efficiency. The presented LP formulation provides a practical solution that can be implemented in general casting plants. Hopefully, the proposed LP scheduling method will assist the casting industry to strengthen its competence by achieving cost minimization and fulfillment of the production requirement within a due date.
Tool shape design in the sheet bending process by inverse analysis of springback
Authors: Behrouzi A , Dariani B M , Shakeri M
Published: June 2009

Elastic recovery of formed parts in unloading, known as springback, causes shape error in the final product of sheet metal forming processes. The final product shape deviates from the target geometry owing to the springback. In the present paper, an analytical approach is proposed for springback analysis in the sheet bending process. By development of this approach for inverse springback analysis, an inverse algorithm for compensation of the springback error is proposed. In the inverse algorithm, the modified die geometry is obtained from the target geometry by inverse springback modelling. The proposed compensation algorithm is adapted to apply the finite element (FE) method for the inverse analysis of springback. The capability of the proposed algorithms is verified in the asymmetric bending process. The optimum die shape for producing the target geometry is obtained in a few trials. Both algorithms present high accuracy and convergence rate. The results of the analytical approach are in accordance with the FE approach with high precision. The accuracy of the presented algorithms is investigated by performing an experimental asymmetric bending test. The optimum shape obtained from the compensation algorithm is applied to produce the bending die. The obtained product matches to the target geometry with high precision. The analytical algorithm is fast and accurate for springback compensation in the bending processes. The FE algorithm is not as fast as the analytical approach, but it enables more complicated three-dimensional processes to be analysed.
Deformation modes coupled analysis in the forging process of disc-shaped components
Authors: Li F , Chu G N , Lin J F , Yuan S J
Published: June 2009

In order to understand the intrinsic character of metal flow during the forging of disc-shaped components, investigations of the effects of die shape on metal flow behaviour were conducted based on a wheel hub part, using the finite element method and experiment, and the regularity of metal flow was analysed. The results indicate that the female die with the cone angle makes the metal flow into the die cavity more easily during forming, which supplied with theoretical references for the investigation on the plastic forming of complicated forgings. From a plastic mechanics viewpoint, the deformation of closed-die forging can be divided into three basic deformation modes: cylindrical compression, ring compression, and pseudo-extrusion; this enables the analysis of forging to be modularized. By analysing different deformation modes and coupled flowing behaviours, the rule of metal flowing was disclosed for complex components.
Cavitating flow in non-circular opening spool valves with U-grooves
Authors: Lu L , Zou J , Fu X , Ruan X D , Du X W , Ryu S , Ochiai M
Published: June 2009

Cavitating flow in non-circular opening spool valves with U-grooves has been investigated in this article. Multifarious cavitating properties, including acoustic cavitation, morphologic cavitation, and discharge performance with cavitation, are investigated, the correlations of which are discussed. The critical opening condition in each valve is obtained based on the analysis of a throttling model. It is found that the cavitating properties show remarkable differences in the two situations when the opening is larger and smaller than the critical opening. Additionally, cavitation impacts on the discharge performance are investigated with the assistance of acoustic and visual detection.
Investigation of mechanisms for separated flow transition control using surface grooves on a high-lift low-pressure turbine profile
Authors: Luo H , Qiao W , Xu K
Published: June 2009

Large-eddy simulation computations were performed to investigate the passive flow control mechanisms for surface groove placed span-wise across a high-lift low-pressure turbine blade to control the separated flow transition. Three cases of grooves at different locations on the suction surface were involved in simulations. Compared with the smooth suction surface, the numerical results show that all grooves are effective to reduce the calculated loss at Reynolds number of 5×104 (based on the inlet conditions and axial chord length), because of the thinning of the boundary layer behind the groove for the groove case with the groove trailing edge front of the separation point, and because of the earlier transition inception promoted for all groove cases. It is suggested that the grooves change the instability prosperities of the velocity profile downstream and cause instability waves predominating the transition process. Upstream movements of the transition inception on the grooved surfaces are the result of changes in the most unstable frequencies and the initial amplitude of instability waves at the most unstable frequencies. The results at Reynolds number of 1×105 suggest that the effect of groove on the location of transition inception is more significant for higher Reynolds numbers. The transition onset can be induced inside the groove at a high Reynolds number, leading to the turbulent boundary-layer-generated loss predominating in the profile loss and the negative effect of the groove appearing.
The use of biofuel emulsions as fuel for diesel engines: A review
Authors: Kumar M Senthil , Bellettre J , Tazerout M
Published: June 2009

Animal fats/vegetable oils (called biofuels) and their emulsions are quite promising alternative fuels for diesel engines. This article reports a comprehensive study on the use of animal fats/vegetable oils and their emulsions as fuel in compression ignition engines. Emulsions preparation method and their effects on engine performance, emission, and combustion characteristics have been studied in detail.

Information indicates that biofuel emulsions in diesel engines enhanced the combustion efficiency with improved performance as compared to neat fuels. The maximum percentage of water addition to biofuel was found as 30 per cent by volume for maximum efficiency. They reduced NO x, smoke, and particulate emissions considerably. Emulsions resulted in higher ignition delay as a result of vaporization of water as compared to neat fuels. Peak pressure, rate of pressure rise, and premixed combustion rate in the heat release curve were found to be higher when compared to neat oils because of longer ignition delay. Further improvements could be achieved by adding oxygenated fuels like methanol, dimethyl carbonate, and cetane number improvers like diethyl ether with biofuels in small quantities. It has also been suggested that dual fuel operation can significantly reduce particulate and NO x emissions with biofuels. Exhaust gas recirculation can reduce ignition delay considerably with reduced NO x emissions. Finally, modelling techniques were presented because they can help in in-depth analysis of the combustion process of biofuel emulsions in diesel engines.
Robust stability analysis for delayed Cohen-Grossberg-type bidirectional associative memory neural networks with norm-bounded uncertainties
Authors: Wang Y , Hu P
Published: June 2009

In this paper, the problem of global robust stability is discussed for uncertain Cohen-Grossberg-type (CG-type) bidirectional associative memory (BAM) neural networks (NNs) with delays. The parameter uncertainties are supposed to be norm bounded. The sufficient conditions for global robust stability are derived by employing a Lyapunov-Krasovskii functional. Based on these, the conditions ensuring global asymptotic stability without parameter uncertainties are established. All conditions are expressed in terms of linear matrix inequalities (LMIs). In addition, two examples are provided to illustrate the effectiveness of the results obtained.
Development of a cascaded controller for temperature and core growth rate in vapour-phase axial deposition
Authors: Jenkins H E , Nagurka M L
Published: June 2009

A cascaded feedback control strategy for an industrial vapour-phase axial deposition (VAD) process is investigated in this paper. VAD is a widely used process in the creation of high-purity glass for optical fibre. In previous work a soot tip surface temperature controller was developed for the VAD process to reduce the effects of core soot temperature variation on deposition geometry, leading to a more stable process. However, it is desired to regulate both the core soot and clad soot such that they deposit at the same axial rate to provide a more uniform product. This paper presents the development of a cascaded controller strategy and process model to couple and regulate the surface temperature and deposition rates of core and clad soot. Simulation studies demonstrate a potential improvement in the uniformity of the core and clad soot geometry over the soot product length.
Practical design of a liquid rate gyroscope using an electro-conjugate fluid
Authors: Takemura K , Yokota S , Imamura T , Edamura K , Kumagai H
Published: June 2009

An electro-conjugate fluid (ECF) is a kind of dielectric fluid that works as a functional/smart fluid generating a powerful jet flow (ECF jet) when subjected to a high d.c. voltage. The authors previously proposed the first liquid rate gyroscope in the world using ECF. The ECF liquid rate gyroscope proposed uses the drift of the ECF jet due to the Coriolis force when an angular motion is applied. The contribution of the proposed concept to gyroscope technology is that it provides the possibility of a low-cost micro gyroscope with inherent robustness to external impact. To move beyond a mere laboratory curiosity, the present paper describes the practical design of an ECF liquid rate gyroscope and characterizes the prototype. The ECF liquid rate gyroscope developed in this study has a scale factor, range of detection, resolution, and linearity of 32 mV/(°/s), ±400°/s, 0.04°/s, and 2 per cent of full scale (with a range of ±60°/s), respectively. These results show that the ECF liquid rate gyroscope could possibly become the next generation standard of micro gyroscopes.
Frequency-domain analysis of intermittent control
Authors: Gawthrop P J
Published: June 2009

Intermittent control is a feedback control design method that combines both continuous-time and discrete-time domains. A recent result shows that this form of intermittent control can be rewritten as a sampled-data feedback system with a particular vector generalized hold. This paper builds on this result to give, for the first time, a frequency-domain analysis of the closed-loop system containing an intermittent controller. This analysis is illustrated using two examples. The first example is related to the human balance control system and is thus physiologically relevant. The second example gives a theoretical explanation of the phenomenon of self-induced oscillations in intermittent control systems.
The influences of geometrical parameters on the failure response of two serial pinned/bolted composite joints
Authors: Sen F , Sayman O
Published: June 2009

In this study, the influences of geometrical parameters on the failure response of two serial pinned/bolted composite joints were analysed. The tested composite material consisted of epoxy matrix and glass fibres. It was oriented as [0°/ 0°/ 60°/ 60°]s, symmetrically. Three different geometrical parameters, which were the edge distance-to-hole diameter ratio ( E/ D), plate width-to-hole diameter ratio ( W/ D), and the distance between two serial holes-to-hole diameter ratio ( K/ D), were investigated, experimentally. Consequently, E/ D, W/ D, and K/ D ratios were designed from 1 to 5, 2 to 5, and 3 to 5, respectively. Additionally, the failure tests were performed for a range of preload moments as 2, 3, 4, 5Nm and without any preload moment as 0Nm. Experimental results showed that the changing of geometrical parameters and the presence of preload moments affected failure behaviour of two serial pinned/bolted composite joints. Furthermore, the numerical failure analysis was also carried out via Lusas 13.6 code. Hashin failure criterion was preferred to determine both bearing strengths and failure modes. All in all, a good agreement is observed between experimental and numerical failure analyses.
Experimental study of recompression reaction for low-load operation in direct-injection homogeneous charge compression ignition engines with n-heptane and i-octane fuels
Authors: Song H H , Padmanabhan A , Kaahaaina N B , Edwards C F
Published: June 2009

Experiments have been reported in the literature in which the low-load limit of a retention-mode HCCI engine operating on gasoline has been significantly extended by pre-processing of the fuel during negative valve overlap. This paper presents experimental studies in which this low-load-limit extension is demonstrated and characterized using simple, single-component hydrocarbon fuels with relatively well-known chemical kinetics. The model fuels were n-heptane and i-octane and this choice was made both because of the extensive work that has been undertaken to develop their chemical kinetic mechanisms and because these fuels span the range of ignitability that is likely to be of interest for HCCI engines.

The experimental results reported here show that both fuels exhibit load extension to as low as 1 bar net indicated mean effective pressure when operated at high residual mass fractions, low equivalence ratios, and an appropriate choice of compression ratio (13 for n-heptane, 18 for i-octane). Near the low-load limit, combustion is stable, exhibits slightly advanced timing, has relatively low unburned hydrocarbon emissions, negligible (< 5 ppm) NO emissions, and slightly increased CO emissions (compared to higher load conditions). The indicated efficiency of low-load operation with recompression reaction is somewhat reduced, mainly due to increased heat transfer and decreased combustion efficiency.
Understanding chemical effects in low-load-limit extension of homogeneous charge compression ignition engines via recompression reaction
Authors: Song H H , Edwards C F
Published: June 2009

In-cylinder pre-processing (or recompression reaction) of pilot-injected fuel during negative value overlap (NVO) has been investigated as a method to extend the low-load limit of residual-effected homogeneous charge compression ignition (HCCI). In an effort to elucidate the chemical and thermal effects involved, model calculations have been performed on the recompression reaction and ignition delay of the recompression products using a reduced n-heptane mechanism (160 reactions, 1424 reactions) and a zero-dimensional kinetics model. Parametric studies were performed to cover possible operating choices for HCCI and to understand their effects on the recompression reaction and mixture ignitability. From the study it is demonstrated that the extent of recompression reaction is limited by chemical kinetics, not thermodynamics, and that residual oxygen during NVO is a determining species for the extent and speciation of the recompression reaction. The recompression product mixture exhibits an overall shorter ignition delay than those of the base fuel, except under lean conditions when significant oxidation during NVO leaves only a small amount of fuel available for main ignition. The thermal consequence of the recompression reaction is also largely dependent on oxygen: at near-stoichiometric conditions, the recompression reaction is endothermic from fuel pyrolysis, whereas at lean conditions, the exothermic recompression reaction becomes dominant. Therefore, the chemical and thermal consequences of the recompression reaction exhibit competing effects on mixture ignitability, which leads to an optimum oxygen concentration (equivalence ratio) for reducing ignition delay and extending HCCI operability.
Impact of filtration velocities and particulate matter characteristics on diesel particulate filter wall loading
Authors: Yapaulo R A , Wirojsakunchai E , Orita T , Foster D E , Akard M , Walker L R , Lance M J
Published: June 2009

The impact of different types of diesel particulate matter (PM) and different sampling conditions on the wall deposition and early soot cake build-up within diesel particulate filters has been investigated. The measurements were made possible by a newly developed diesel exhaust filtration analysis system in which in-situ diesel exhaust filtration can be reproduced within small cordierite wafer disks, which are essentially thin sections of a diesel particulate filter wall. The different types of PM were generated from selected engine operating conditions of a single-cylinder heavy-duty diesel engine. Two filtration velocities 4 and 8 cm/s were used to investigate PM deep-bed filtration processes. The loaded wafers were then analysed in a thermal mass analyser that measures the soluble organic fraction as well as soot and sulphate fractions of the PM. In addition, the soot residing in the wall of the wafer was examined under an optical microscope illuminated with ultraviolet light and a variable pressure scanning electron microscope to determine the bulk soot penetration depth for each loading condition.

It was found that a higher filtration velocity results in a higher wall loading with approximately the same penetration depth into the wall. PM characteristics impacted both wall loading and soot cake layer characteristics. Results from imaging analysis indicate that the soot penetration depth into the wall was affected more by PM characteristics (which changes with engine operating conditions) than by filtration velocity.
Estimation of hull girder vertical bending moments including non-linear and flexibility effects using closed form expressions
Authors: Pedersen P T , Jensen J J
Published: June 2009

A simple but rational procedure for prediction of extreme wave-induced hull girder bending moment in slender mono-hull displacement vessels is presented. The procedure takes into account main ship hull characteristics such as length, breadth, draught, block coefficient, bow flare coefficient, forward speed, and hull flexibility. The wave-induced loads are evaluated for specific operational profiles.

Non-linearity in the wave bending moment is modelled using results derived from a second-order strip theory and water entry solutions for wedge-type sections. Hence, bow flare slamming is accounted for through a momentum type of approach. The stochastic properties of this non-linear response are calculated through a monotonic Hermite transformation. In addition, the impulse loading attributable to, for example, bottom slamming or a rapid change in bow flare is included using a modal expansion in the two lowest vertical vibration modes. These whipping vibrations are added to the wave frequency non-linear response, taking into account the rise time of the impulse response as well as the phase lag between the occurrence of the maximum non-linear load and the maximum impulse load. Previous results for the sagging bending moment are validated by comparison with fully non-linear strip theory calculations and supplemented with new closed form results for the hogging bending moment. Focus is on the extreme hull girder hogging bending moment. Owing to the few input parameters, this procedure can be used to estimate the wave-induced bending moments at the conceptual design phase. Another application area is for novel single-hull ship types not presently covered by the rules of the classification societies. As one application example the container ship MSC Napoli is considered. Further validations are needed, however, in order to select proper values of the parameters entering the analytical form of the slamming impulse.
Advances in the three-dimensional hydroelasticity of ships
Authors: Wu Y-S , Cui W-C
Published: June 2009

The study of hydroelasticity of ships first gained momentum in the late 1970s with the work of Bishop and Price, who established the two-dimensional (2D) hydroelasticity theory of ships. The concept and basic principle presented in their work to embody the structure and the surrounding fluid as a coupled entirety was further employed and extended in the creation of the general linear three-dimensional (3D) theory of hydroelasticity for an arbitrary shaped flexible marine structure travelling with a forward speed in a seaway in the middle of 1980s (Wu, 1984; Price and Wu, 1985a; Bishop et al., 1986). Since then, great progress has been achieved in the development and application of 3D hydroelasticity theories. These include the more rigorous methods of frequency-domain linear analysis accounting for the forward speed effect and the steady flow effect, the time-domain linear 3D theory, the non-linear 3D theory and the numerical methods for a floating structure travelling in rough seas with large motions, experimental techniques of 3D flexible ship models, the hydroelasticity-based design and safety assessment, etc. This paper presents an overview of these developments and achievements of linear and non-linear 3D hydroelasticity theories of ships, and the corresponding numerical and experimental techniques.
Hydroelasticity of ships: Recent advances and future trends
Authors: Hirdaris S E , Temarel P
Published: June 2009

Investigations into hydroelasticity of ships commenced in the 1970s. Since then the theory has been employed to predict the responses of a wide range of marine structures, such as mono- and multihulled ships, offshore structures, and VLFS. In recent years, with increasing market demands for new buildings of slender ocean going carriers and the continuously updated high-speed and unconventional multihulled designs, the maritime industry began to notice the advantage of assessing the usefulness and applicability of hydroelasticity in ship design.

At first instance, the aim of this paper is to illustrate some of the applications of hydroelasticity theory to ships, with particular reference to recent and ongoing developments focusing on ship design applications and the effects of non-linearities and viscous flows. The paper also discusses the longer term potential use of weakly and fully non-linear fluid—structure interaction, as well as Navier—Stokes based fluid dynamic methods, for the improved modelling of ship dynamic response problems.
Positronics and nanotechnologies: Possibilities of studying nano-objects in technically important materials and nanomaterials
Authors: Chaplygin Y A , Gavrilov S A , Grafutin V I , Svetlov-Prokopiev E , Timoshenkov S P
Published: June 2009

This article shows that an effective method to define the size of nano-objects (vacancies, vacancy, clusters, free pore volumes, cavities, and holes), and their concentration and chemical composition, is positron annihilation spectroscopy (PAS). A review of the state of the art of the application of the PAS technique to probe nanostructures in porous silicon, silicon and single crystal quartz samples is presented.
Preparation of ordered mesoporous TiO2 and its photocatalytic activity
Authors: Niu K , Chu H , Ni Z-B , Chen M-Q
Published: June 2009

A transparent TiO2 gel was prepared by the sol-gel method using a block copolymer (P123) as the template agent and titanium isopropoxide (TTIP) as the inorganic precursor. Ordered mesoporous TiO2 was obtained after calcination. The structure, morphology, crystalline size, specific surface area, pore size, and photocatalytic activity of the resultant samples were characterized using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and N2 adsorption—desorption techniques. The sample obtained at 400°C shows good crystallization and had a surface area of 334m2/g with a pore size of 7.8nm. The mesoporous TiO2 showed high activity in photodecomposing methyl orange solution: 40ml methyl orange solution (20mg/l) completely decomposed within 30min. The photodecomposition ratio of the product is much higher than commercially available TiO2 nanoparticles and the high photocatalytic activity remains after regeneration.
The hysteresis loop and switching field in the bilayer film
Authors: Ma Y , Du A , Hu Y
Published: June 2009

In recent years, some attention has been devoted to composite magnets by combining the best performance of a magnetic material with different anisotropies via exchange coupling. In particular, thin composite films based on magnetic recording have been extensively studied. The case in which one layer with easy-axis anisotropy is coupled to another layer with easy-plane anisotropy is considered. From a theoretical view point, many investigations based on micromagnetic simulation are used to describe a two-phase system. In this paper, the Heisenberg model is utilized to describe a bilayer film system. The magnetization of the system is calculated by the self-consistent effective field theory in an applied magnetic field. The interaction coupling between the soft layer and the hard layer could not be changed, the variation in the ratio of the anisotropies of the bilayer is considered. The hysteresis loop is calculated in an applied field under different directions.
Phospholipid coating on a polydimethylsiloxane microchannel wall to minimize aqueous evaporation in microdroplet maintenance
Authors: Huang H M , Jiang J H , Ma X D , Wang J , Dong G X , Paul Sung K-L
Published: June 2009

In this paper, some factors governing the evaporation rate of aqueous microdroplets generated in a newly developed PDMS (polydimethylsiloxane) microchannel device were examined. Microdroplets of about 0.25nL, composed of any one of the conventional solvents (including water, ethanol, and hexane) were found to be disappearing in about 1 h in a PDMS microchannel (diameter 80μm) when exposed to heating under light microscopy, although this slightly slowed down when placed in an ambient environment. Furthermore, when the inner wall of the PDMS microchannel was microfluidic coated by phospholipid solution, aqueous microdroplets could be maintained with no volume-loss up to at least 1 h.
Reactive ion exchange synthesis of high-purity ZnO nanoparticles
Authors: Zhu S-M , Li J-Y , Li Y-S , Wang Y , Jiang Y-L
Published: June 2009

High purity ZnO nanocrystals were prepared by a one-step reactive ion exchange procedure Zn(NO3)2 and strong basic anion-exchange resins were used as the raw materials. The particle sizes of the nanocrystals were between 30 and 50nm. The products were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and ultraviolet—visible spectroscopy. The ZnO nanocrystals had a hexagonal wurtzite structure, whose ratio of length to diameter was more than 10:1. The synthesized ZnO powders were successfully used as catalyst materials for methyl orange photogradation.
Rhodamine–Pyridyl Probe: A Selective Optical Reporter for Biologically Important Zn2+
Authors: Mashraqui Sabir H , Khan Tabrez , Sundaram Subramanian , Betkar Rupesh , Chandiramani Mukesh
Published: June 2009

A new Rhodamine-based probe, Rhoda-P affords remarkably selective chromo- and fluorogenic responses in the presence of Zn2+ with the color turning from colorless (λmax=302 nm) to orange (λmax=528 nm) and the fluorescence output increased by 160-fold at 1.5×10−3 M of Zn2+. In contrast, Li+, Na+, K+, Ba2+, Ca2+, Mg2+, Co2+, Ni2+, Cu2+, and Cd2+ did not significantly alter the photophysical properties of the probe even at relatively higher concentrations than Zn2+.
Ene Reaction Using the Iminium Salt Generated by the Oxidation of Aminoketene Silyl Aetal
Authors: Shimizu Makoto , Itou Hiroyuki , Iwao Takuya , Umeda Yuki
Published: June 2009

Ene reaction of various olefins proceeded with the iminium salt generated by the oxidation of aminoketene silyl acetal to give addition products in good yields.
Synthesis of Cyano-substituted Through-space Poly(p-arylenevinylene)
Authors: Morisaki Yasuhiro , Lin Lin , Chujo Yoshiki
Published: June 2009

The Knoevenagel reaction of pseudo-p-bis(cyanomethyl)[2.2]paracyclophane with 2,5-dialkoxy-1,4-diformylbenzene was carried out to yield the cyano-substituted through-space poly(arylenevinylene). Thermal, optical, and electrochemical properties are described.
On Longitudinal Vortices in Turbulent Jets at Aeroacoustic Interactions
Authors: Pimshtein V.G.
Published: June 2009

Experimental results are presented on the generation of longitudinal vortices in turbulent jets using sawtoothed high-intensity sound waves excitation. The flow and sound waves were visualized by the direct shadowgraph method. It is shown that at external and internal acoustic excitation the streamline curvature and velocity growth direction in the generated vortices are favourable for Görtler instability appearance, and the formed longitudinal vortices can by identified as Taylor-Görtler vortices
Screech Frequency Prediction in Underexpanded Axisymmetric Screeching Jets
Authors: Chatterjee Avijit , Ghodake Dipali , Singh Ashish
Published: June 2009

Average shock spacing and average standing wavelength are estimated from computed near-field of axisymmetric underexpanded screeching jets at low supersonic Mach numbers. These are used to predict screech frequencies based on existing formulations which rely either on shock spacing or on standing wavelength. Results obtained suggest that shock spacing and standing wavelength may respectively be dominant length scales for A1 and A2 axisymmetric screech modes observed for axisymmetric jets at low supersonic Mach numbers. This implies that presence of two axisymmetric screech modes in supersonic jet screech could be attributed to the two co-existing length scales in the jet near-field.
Noise Spectra and Directivity for a Scale-Model Landing Gear
Authors: Humphreys William M. , Brooks Thomas F.
Published: June 2009

An extensive experimental study has been conducted to acquire detailed noise spectra and directivity data for a high-fidelity, 6.3%-scale, Boeing 777 main landing gear. The measurements were conducted in the NASA Langley Quiet Flow Facility using a 41-microphone directional array system positioned at a range of polar and azimuthal observer angles with respect to the model. DAMAS (Deconvolution Approach for the Mapping of Acoustic Sources) array processing as well as straightforward individual microphone processing were employed to compile unique flyover and sideline directivity databases for a range of freestream Mach numbers (0.11 – 0.17) covering typical approach conditions. Comprehensive corrections were applied to the test data to account for shear layer ray path and amplitude variations. This allowed proper beamforming at different measurement orientations, as well as directivity presentation in free-field emission coordinates. Four different configurations of the landing gear were tested: a baseline configuration with and without an attached side door, and a noise reduction concept “toboggan” truck fairing with and without side door. Spectral analyses demonstrated that individual microphones could establish model spectra. This finding permitted the determination of unique, spatially-detailed directivity contours of spectral band levels over a hemispherical surface. Spectral scaling for the baseline model confirmed that the acoustic intensity scaled with the expected sixth-power of the Mach number. A comparison of spectra and directivity between the baseline gear and the gear with an attached toboggan indicated that the toboggan fairing may be of some value in reducing gear noise over particular frequency ranges. Finally, spectrum results were scaled quantitatively to data obtained from flyover tests of a full-scale 777 aircraft. The comparison showed good agreement in frequency and level, suggesting the general applicability of the model-scale noise results.
Wearable Personal Assistants for the Management of Historical Centers
Authors: Izkara J.L. , Basogain X. , Borro D.
Published: June 2009

One of the main tasks facing the manager of a historical centre is to avoid degradation while retaining the historical value. For this reason, any intervention which takes place on the environment, should be carefully managed. Only when performing a proper diagnosis of the environment and its reality is possible to follow a high quality intervention. The integration of new information technologies has been crucial to the improvement of these processes providing new tools. Within the project called RASMAP, we have designed and implemented a mobile augmented reality platform based on a service oriented architecture. This project introduces the concept of Wearable Personal Assistant (WPA). WPA in the RASMAP platform represents an innovative wearable tool, which provides support to professionals in their daily activities (mechanical engineer, safety responsible person, diagnosis expert, etc.). This tool is based on augmented reality technologies, mobile devices and communication infrastructures. The development of the platform for the WPAs implies addressing several technological challenges: a) to overcome the limitations inherent in the mobile devices: speed, capacity of memory, capacity of storage, graphical features and others, b) to obtain tracking systems that they do not need to alter or to adapt the environment, c) to optimize for the transmission and reproduction of multimedia contents through wireless networks on mobile devices. In this article, we describe the RASMAP platform, as a basis for the development of WPA and the extension of its use for the management of historical centres. The quality and usefulness of the scientific-technological results provided by the WPA have been validated developing a demonstrator for the diagnosis of the conservation status of the historical centre of a small town in the Basque Country. The advantages to be gained by using WPA in the proposed scenario are among others: more efficient processes, improved communication between users, and local and distributed multimedia content records.
3D Collaborative Environments in Archaeology: Experiencing the Reconstruction of the Past
Authors: Forte Maurizio , Pietroni Eva
Published: June 2009

This paper presents the outcome of the research project: “Integrated Technologies of Robotics and Virtual Environments in Archaeology”, financed by the Italian Ministry of the University and Scientific Research, FIRB (Funds for the Investments of Basic Research). The aim of the project is to experiment and realize a multi-user domain on the web aimed to a multidisciplinary scientific community: archaeologists, historians, experts in human and social sciences, communication experts. The capacity to load, share and interact with data in the same spatial virtual environment can increase the level of learning and scientific communication. The project is the result of the collaboration between CNR-ITABC of Rome, the University of California, Merced, the Department of Archaeology of the University of Pisa and Scuola S. Anna of Pisa. It focuses on three archaeological sites: the Teban tomb 14 in the necropolis of Gurna, Fayum Medinet Madi, both in Egypt, and Khor Rori, in Oman. The collaborative environment is constructed through a virtual reality system. This allows to create a virtual space where it is possible to share 3D information on the project and to host additional behaviors of the scientific community.
Contemporary Digital Methods for the Geometric Documentation of Churches in Cyprus
Authors: Georgopoulos A. , Ioannidis Ch , Chrysostomou Ch , Ioakim S. , Shieittanis N. , Ioannides M.
Published: June 2009

Recent advances in digital methods incorporating information technology have enabled the traditional surveyor and monument recorder to work faster, more accurately and in an automated way in order to produce advanced digital products, more versatile and more useful to the end users. Such methods include tacheometry, digital photogrammetry, as image-based method, terrestrial laser scanning and the development of specialized software in order to fully exploit the digital data acquisition. Usually, a combination of these methods gives the most efficient cost benefit results, by providing 2D vector and raster products and 3D textured models. In this paper two examples of the implementation of these methods in the geometric documentation of two churches, both significant for the history of Cyprus, are presented. It is concerned with the churches of Virgin Mary (Panayia) Podithou, in Galata and St. George Nikoxylitis in Droushia. The applied methodology, using classical and contemporary techniques of commercial and in-house developed software is presented. Comparative tests for the achieved accuracies and the completeness of each method's products have been made, and their merits and usefulness are explained.
Worth a Thousand Words? The Usefulness of Immersive Virtual Reality for Learning in Cultural Heritage Settings
Authors: Tost Laia Pujol , Economou Maria
Published: June 2009

The goal of this paper is to investigate whether immersive virtual reality is suitable for learning about archaeology and the past in cultural heritage settings. To that end it presents the conclusions related to learning from the visitors' survey undertaken in 2007 by the Museology Laboratory of the University of the Aegean at the Hellenic Cosmos (the exhibition centre of the Foundation of the Hellenic World) in Athens, and contrasts these with other similar studies. This project was aimed at comparing the learning outcomes, perception and use by audiences of two different virtual reality systems and a related exhibition. It included qualitative and quantitative analysis of the data gathered through in situ observations, interviews with museum educators and face-to-face questionnaires with visitors. The results confirmed that, as previous studies have shown, virtual reality systems allow a different kind of learning, but also questioned the common believe about their advantage for children in comparison with other interpretation methods.
Monitoring Archaeological Site Landscapes in Cyprus Using Multi-Temporal Atmospheric Corrected Image Data
Authors: Hadjimitsis D.G. , Themistocleous K. , Agapiou A. , Clayton C.R.I.
Published: June 2009

This paper aims to examine the use of satellite remote sensing for monitoring archaeological and more generally cultural heritage sites. For this purpose, multi-temporal data from Landsat 5 TM, Landsat 7 ETM+ and Quickbird images were applied. The paper also discusses the importance of atmospheric correction at the pre-processing step in order to determine true surface reflectance values by removing these effects from satellite images. Atmospheric correction is arguably the most important part of the pre-processing of satellite remotely sensed data and any omission produces erroneous results. The effects of the atmosphere are more severe where dark targets are shown in the satellite image. In the management of cultural heritage sites, since temporal satellite images are required for monitoring purposes, the effect of the atmosphere must be considered. In-situ spectro-radiometric measurements using the GER1500 field spectro-radiometer have been used to assess the reflectance values found after applying the darkest pixel atmospheric correction to the image data. The study area consist the Amathus archaeological site in Limassol and the Nea Paphos archaeological site area located in Paphos district area in Cyprus. Vegetation Index (NDVI) change detection algorithm has been applied to a series of thirteen Landsat TM/ETM+ images of Amathus archaeological site in Limassol. Classification and extraction algorithms have been applied to Landsat TM and Quickbird high resolution images of Nea Paphos archaeological site area.