bluuebunny/crossref_metadata_2025 huggingface dataset:
Fe-Simulation of Hot Continuous Rolling of 40Cr Alloy Steel Round Bar and Roll Pass Design
Authors: Hong Hui Ping , Luan Yu
Published: April 2015

40Cr alloy steel is widely used in the mechanical manufacturing industry and the quality of its rolled round bar has a great consequence on the quality and useful time of the final mechanical parts. By analyzing the characteristics of thermal plasticity of 40Cr steel, the Hensel-Spittel flow stress model of 40Cr steel was established in this study. For the possible continuous rolling schedule of Φ80mm 40Cr steel from 200mm×200mm billet, the advanced technology of viscoplastic FEM by LARSTRAN/SHAPE was used to create 3-D thermo-mechanical coupled simulation models for 8-pass hot continuous rolling processes. From the rolling process simulation the stress, strain, temperature distribution and rolling force variation were obtained. The simulation results included the comparison of plastic deformation of round pass with curved side wall and round pass with straight-side wall as well as the cause of rolling defect (e.g. crack). Based on the numerical analysis the reliable roll pass sequence wa constructed, which was verified by actual tests.
Microstructure, Corrosion and Wear Resistance of Co-Ni-ZrO2 Composite Coating
Authors: Gao Jun , Sun Wan Chang , Shi Qin , Wang Ying , Tian Miao Miao
Published: April 2015

Co-Ni alloy and ZrO2 submicron particles were successfully co-deposited on carbon steel substrate by direct current electrolytic deposition. The micromorphology, constituent, microhardness, corrosion and wear resistance of the composite coatings were tested, respectively. The results show that the embedded submicron ZrO2 particles are uniformly distributed in the entire Co-Ni matrix and the coating showed a good adhesion to the substrate. The hardness, friction coefficient, wear loss, and electrode voltage of Co-Ni alloy coating were 356 HV, 0.8, 1.901×10-2 mg/m, and-0.47 V, respectively, while those of Co-Ni-ZrO2 composite coating were 413 HV, 0.6, 1.174×10-2 mg/m, and-0.37 V, respectively. The data above suggested that Co-Ni-ZrO2 composite coating possesses higher microhardness, better wear and corrosion resistance.
Influence of Magnetic Field on the Microstructure and Properties of Cu-Ag-Zr Alloy
Authors: Li Hang , Jia Chun Xu , Zhang Peng Chao , Jie Jin Chuan , Li Ting Ju
Published: April 2015

Cu-Ag-Zr alloy is a newly developed copper alloy material with an excellent combination of high mechanical strength and high electrical conductivity. Magnetic field was used in the solidification of Cu-Ag-Zr alloy. The results showed that with the application of magnetic field, formerly coarse columnar grain turned into homogeneous equiaxed grain. After aging, the precipitate of Zr had an increment and became more refined due to the reduction of segregation. The tensile strength and microhardness of Cu-0.1Ag-0.3Zr alloy under magnetic field of 15 mT increased by 17% and 10%, respectively. The electrical conductivity, with a slight decrease, was still as high as 92.4 %IACS.
Application Research of a New Coupling Stirring on DC Casting Process for Large-Sized Aluminum Ingots
Authors: Wang Hai Jun , Xu Jun , Zhang Zhi Feng , Liang Bo , Gao Ming Wei
Published: April 2015

A new coupling stirring technology was proposed and used to prepare direct chill (DC) ingots. Ingots of 7075 alloy were produced by a process of normal direct chill (NDC) casting and coupling-stirring direct chill (CDC) casting, respectively. The effect of the technology on the microstructures, composition segregation and mechanical properties of the ingots was investigated. The results showed that the temperature variation in the CDC casting process was more uniform than that in the NDC casting process. The grain of the CDC ingots was finer and more spherical than the grain of NDC ingots. The grain size at the edge, 1/2 radius, and center position in CDC ingot decrease by 28%, 22%, and 24% comparing with the grain size of the corresponding positions of NDC ingot, respectively. The billets with higher performance and lower macro-segregation were obtained in case of CDC. The flow stresses and the difference in different positions of DC ingots measured at Gleeble-1500D thermo-mechanical simulator decreased obviously when the coupling stirring technology is used in the casting process.
An Advanced Metal Deposition Technique-Kinetic Metallization
Authors: Yu Hai Jiao , Wang Yu Ya , Xue Jun , Wang Zun
Published: April 2015

Kinetic metallization (KM) is a sonic cold spray metal deposition technique, which offers promise as a way to produce coatings with a wild range of thickness. It is a solid-state process, from which the obtained coating is oxide free, high compactness (the porosity ratio may less than 0.1%), and has a strong bonding with the matrix. KM now is extensively applied in many fields, such as part/structure dimensional repair, solar battery manufacture, corrosion resistance and protection, wear resistance, oxidation resistance, and polymer spray. The present work presented the elements and advantages of KM, related it with high velocity oxy-fuel (HVOF) and common cold spray (CS), and reviewed the progress of KM over the two decades. Finally, the further development of the KM was discussed.
Extrusion Simulation and Texture Study on Mg-Y Alloy
Authors: Tang Tao , Shao Yi Chuan , Li Da Yong , Peng Ying Hong
Published: April 2015

In order to study the influence of extrusion process on texture development of alloys, numerical simulation methods were used to simulate the round and shape extrusion process and deformation texture. Extrusion of Mg-Y magnesium alloy was carried out at the temperature of 673K with different ram speeds to verify the simulation results. Instead of using the Lagrangian FE method, the Arbitrary Lagrangian-Eulerian (ALE) method was employed in this study so that a more accurate description of the steady-state extrusion process can be achieved. By obtaining strain histories of specified material tracer particles, the coupling of deformation and crystal plasticity theory was applied to simulate the texture evolution in hot extrusion. The results showed that the texture simulation corresponded well with the experimental ones. The study proposes a method to analyze the steady-state extrusion process and texture evolution, and can be used as a useful tool in optimizing the extrusion process.
Differential Scanning Calorimetry Studies on Ni-Ni3B Alloys
Authors: Xu Jun Feng , Liu Feng , Zhu Man , Jian Zeng Yun
Published: April 2015

Solidification behaviors of hypoeutectic Ni-3.3wt% B and hypereutectic Ni-4.5wt% B alloys were investigated by using differential scanning calorimetry (DSC) technology. Experimental results showed that the solidification behaviors are similar for the two kinds of alloys with small sizes, i.e. three transformed peaks (corresponding to L→α-Ni, L→Ni-Ni23B6and Ni23B6→Ni+Ni3B, respectively) appear in the cooling curves, and three phases (primary phase α-Ni, rod eutectic and dot precipitates) appear in the microstructures, which are different from that of the alloys with large sizes. It can be attributed to the fact that the nucleation of α-Ni and Ni23B6phases are easier than that of Ni3B phase for small samples of hypoeutectic and hypereutectic Ni-Ni3B alloys.
Effect of Mo on Transformation, Microstructure and Property of Hot-Rolled DP600 Steel
Authors: Zhou Le Yu , Cui Tian Hao , Jiang Bo , Zhang Chao Lei , He Jian Zhong , Liu Ya Zheng
Published: April 2015

In according with the transformation rules of C-Si-Mn-Cr and C-Si-Mn-Cr-Mo tested steels, rolling experiment was carried out in lab. to analyze the effect of Mo on transformation, microstructure and property of high strength hot rolled dual phase steels. The results showed that the addition of element Mo decreased start temperature of ferrite transformation and restrains pearlite transformation. There was a metastable austenite zone between ferrite and bainite transformation zone of No.2 steel with 0.35% of Mo. After controlled rolling and step cooling process, dual phase microstructures in which fine martensite islands dispersed in soft ferrite matrix were obtained by two kinds of tested steel. With the addition of Mo, yield strength and tensile strength increased by 80MPa and 60MPa respectively, meanwhile, elongation increased slightly.
Influence of FeCrAl Coating Arc Sprayed on Aluminum Corrosion Resistance of H13 Steel
Authors: Zhao Jian Hua , Wang Li , Shang Zheng Heng
Published: April 2015

FeCrAl coating was prepared on the surface of H13 steel through electric arc spraying (EASP) technology. The surface and cross section morphology, elements and phase composition of the composite coating were analyzed by the means of scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The aluminum corrosion resistance was tested by the static hot-dip aluminum method in molten AC4C aluminum at 700°C. The result showed that the FeCrAl coating, of which the microstructure was compact, had typical layer structure, and a small amount of oxide films and pores could be found among the lamellar particles. FeCrAl coating mainly contained Fe-Cr solid solution and small amounts of Al2O3. The weight of H13 corrosion was 3 times as much as that of FeCrAl coating corrosion after static melting treatment for 1h, and the corrosion rate of H13 steel and FeCrAl coating were both increased as the corrosion time increased from 1h to 3h. It was worthy noted that the weight of H13 corrosion was significantly increased, which was 17 times as much as that of FeCrAl coating corrosion.
Electro-Less Ni-P Plating Coating of In Situ TiCp/Al-4.5wt.%Cu Vomposites
Authors: Liang Yan Feng , Dong Sheng Quan , Li Gao Hong
Published: April 2015

In situ TiCp/Al-4.5wt.%Cu composites have been coated using an electro-less Ni-P plating technique. The morphology and composition of the plating coating have been examined by scanning electron microscopy, optical microscopy, and X-ray diffraction. The results indicated that the coating had a high-phosphorus amorphous microstructure. The coatings microstructures showed significantly changes when the citric acid concentration in the chemical bath was varied in the range 16-20g/L.
Mg Alloy Foam Fabrication via Powder Metallurgy and its Compressive Behavior
Authors: Yang Dong Hui , Hu Zhong Yun , Chen Wei Ping , Chen Jian Qing , Wang Hui , Jiang Jing Hua , Ma Ai Bin
Published: April 2015

This paper reports the required conditions for fabricating Mg-Al alloy foams starting from metallic powders, where CaCO3 was selected as the blowing agent. The molar ratio of Al varied from 0 to 50%. Mg-Al alloy foams with porosity of 30%~80% and pore size around 0.5~2.0 mm were prepared successfully. The process to make foams includes two main procedures, i.e. foamable precursor preparation and foaming procedure. The effects of the three main parameters, i.e. compaction degree, Al addition, foaming temperature on the foaming results were discussed. Finally, the compressive behaviors of Mg alloy foams were investigated.
Effect of Squeeze Casting and Solution Treatment on the Microstructure and Properties of ZA27 Worm Wheel
Authors: Zhu Quan Li , Wu Zi Yong , Chen Jia Jian
Published: April 2015

Compared with permanent mold casting, the microstructure, mechanical properties, friction and wear of squeeze casting ZA27 alloy were studied. The results showed that squeeze casting can reduce or eliminate shrinkage porosity defect, refine or improve the microstructure and the shape and distribution of copper-rich ε phase which leads to the obvious improvement of the performance. In addition, with the increase of solution temperature, higher degree of super-saturation can enhance the tensile strength and hardness of ZA27 alloy. The better deformation coordination is an important factor to the enhancement of elongation. Remelting among grain boundaries leads to the deterioration of performance rapidly.
Effects of Microstructure Transformation on Strengthening and Toughening for Heat-Treated Low Carbon Martensite Stainless Bearing Steel
Authors: Yuan Xiao Hong , Yang Mao Sheng , Zhao Kun Yu
Published: April 2015

Microstructural transformations and mechanical properties of a low carbon martensite stainless bearing steel treated with different heat treatment parameters and cryogenic treatment (-82°C) were investigated. The function of microstructural transformations on strengthening and toughening process was quantitatively characterized as well. These analyses were performed by the optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and electron back scattering diffraction (EBSD) technique. The obtained results show that with execution of cryogenic treatment and tempering, the tensile strength increase owing to the reduction of retained austenite and fine carbides precipitating respectively. The effect of martensitic microstructure on yield strength increment can be regarded as packet size and block width which conform to Hall-Petch relationship. Meanwhile, the results suggest that the block width is the key structural controlling unit when analyzing the strength-structure relationship of lath martensite in low carbon martensite stainless bearing steel. In addition, packet size can be related to toughness controlling as well because of the same size as cleavage plane.
Indenter Size Effect on the Reversible Incipient Plasticity of Al (001) Surface Studied via Quasicontinuum Simulations
Authors: Shao Yu Fei , Yang Xin , Li Jiu Hui , Zhao Xing
Published: April 2015

Indenter size effect on the reversible incipient plasticity of Al (001) surface is studied by quasicontinuum simulations. Two cylindrical indenters with the radii 2.5nm and 17.5nm are used to penetrate the surface respectively, in displacement-control in steps of 0.02 nm. Results show that the plasticity under the small indenter is reversible, since it is dominated by the nucleation of a thin deformation twin, which can be fully removed after withdrawal of the indenter, due to the imaging force and stacking fault energy. Under the large indenter, multiple slip systems are activated simultaneously when incipient plasticity occurs, a few twin, dislocation and stacking fault ribbons still remain under the surface when the indenter has been completely retracted, thus the plasticity is irreversible.
Mesoscopic Simulation of the Ferrite Nucleation on Austenitic Grain Boundary for Nanograined Steel
Authors: Yu Peng , Zhang Lin , Du Lin Xiu , Hu Jun
Published: April 2015

We use the cellular automaton (CA) modeling to investigate the ferrite nucleation on the austenite grains. On the basis of the thermodynamics and kinetics of phase transformation from austenite to ferrite, the CA modeling demonstrates that the size of nucleated ferrite grains is increased with increasing of cooling rates, and nucleation process is finished instantly at a given cooling rate. The initial austenite grain size plays an important role in the obtained ferrite nucleation number, and the potential nucleation cells are increased.
Effects of Hardening Models on CUO Forming and Springback Simulation of High Strength Line Pipes
Authors: Ren Qiang , Zou Tian Xia , Li Da Yong
Published: April 2015

The UOE process is an effective approach for manufacturing the line pipes used in oil and gas transportation. During the UOE process, a steel plate is crimped along its edges, pressed into a circular pipe with an open-seam by the successively U-O forming stages. Subsequently, the open-seam is closed and welded. Finally, the welded pipe is expanded to obtain a perfectly round shape. In particular, during the O-forming stage the plate is suffered from distinct strain reversal which leads to the Bauschinger effect, i.e., a reduced yield stress at the start of reverse loading following forward strain. In the finite element simulation of plate forming, the material hardening model plays an important role in the springback prediction. In this study, the mechanical properties of API X90 grade steel are obtained by a tension-compression test. Three popular hardening models (isotropic hardening, kinematic hardening and combined hardening) are employed to simulate the CUO forming process. A deep analysis on the deformation and springback behaviors of the plate in each forming stage is implemented. The formed configurations from C-forming to U-forming are almost identical with three hardening models due to the similar forward hardening behaviors. Since the isotropic hardening model cannot represent the Bauschinger effect, it evaluates the higher reverse stress and springback in the O-forming stage which leads to a failure prediction of a zero open-seam pipe. On the contrary, the kinematic hardening model overestimates the Bauschinger effect so that predicts the larger open-seam value. Specifically, the simulation results using the combined hardening model show good agreement in geometric configurations with the practical measurements.
Diffusion of Epoxy Molecules on the Chemically Modified Graphene: A Molecular Dynamics Simulation Study
Authors: Zhang Jian Wei , Jiang Cai , Shi Gang , Jiang Da Zhi
Published: April 2015

Buckypaper based polymer composites provides a new technical approach toward realizing conductive/structural multifunctional composites. Resin infiltration in the buckypaper is critical for the fabrication of buckypaper/polymer composites. To investigate the micro-infusion process of the polymer inside the paper, molecular dynamics (MD) simulations are conducted to study the diffusion behavior of epoxy molecules on the modified graphene and between graphene layers. The graphene molecular structures are constructed to represent the wall structures of the carbon nanotubes. Diffusion coefficients of the epoxy molecules on the graphene modified with different functionalization densities and interlayer distances are calculated. The results indicate that the functional groups increase the interfacial interactions between the epoxy molecules and graphene, however, largely decrease the diffusion speeds of the epoxy molecule. The simulations on the graphene layer systems indicate that, the viscous resistance of the resin is the main factor for retarding the diffusion of the epoxy molecules for the unmodified graphene layers; while for the modified graphene layers, functional groups are the main factor for retarding the resin diffusion
Magnesium Alloy AZ31 - Short Carbon Fiber Composite Obtained by Pressure Die Casting
Authors: Olszówka-Myalska Anita , Myalski Jerzy
Published: April 2015

The application of short carbon fibers in magnesium alloy AZ31 matrix composite fabrication by cold chamber pressure die casting was presented. A technological procedure of small-sized and complex-shaped composite casts manufacturing was shown. The microstructure of the composite was characterized as well as its mechanical properties, friction coefficient and wear resistance. The application of mechanical stirring of melted AZ31 alloy with short fibers and then AZ31-Cf suspension pressure die casting ensured obtaining casts with the reinforcing phase correctly distributed and well bonded with the matrix. Comparision of the AZ31-Cf composite with the AZ31 alloy properties, cast in the same conditions, revealed a considerable increase in bending strength and hardness, and some improvement of ductility and sliding friction parameters as a result of short carbon fibers application.
Microstructure of Hypereutectic Mg-Si Alloy with Sn, Al and Mn Additions
Authors: Rzychoń Tomasz
Published: April 2015

In the present study, the microstructure of Mg-5Si alloys with tin, aluminum and manganese was investigated. The microstructure of Mg-5Si alloy consists of the primary coarse Mg2Si phase, α-Mg solid solution and eutectic α-Mg + Mg2Si in which the eutectic Mg2Si phase solidifies in the form of Chinese script particles. The Mg2Sn phase and α-Mg solid solution with tin appear in the microstructure, when 7 wt.% of Sn was added to the Mg-5Si alloy. Aluminum dissolve in the α-Mg matrix and participates in the formation of Al2Sn phase. The addition of manganese promotes the formation of Mn5Si3 compound.
Influence of Heating and Cooling Rate on Phase Transformations Temperatures in EV31A Magnesium Alloy
Authors: Przeliorz Roman , Kiełbus Andrzej
Published: April 2015

Following article summarizes results of the researches concerning influence of heating and cooling rate on the phase transformations temperatures in EV31A magnesium alloy. Particular attention has been paid to calibration aspects of the temperature measurement as well as cooling and heating rates in protective atmosphere. The researches were conducted on Multi HTC calorimeter, provided by Setaram company. The samples were heated up to liquidus temperature with controlled rates of: 2.5°C/min, 5°C/min, 10°C/min, 15°C/min and 20°C/min. Just after melting, the specimens were cooled with the same rates. Equilibrium temperatures of phase transformations were calculated by extrapolation to zero heating/cooling rate. Considerable difference between melting point (during heating) and solidification temperature (during cooling) were noticed on cooling/heating curves. The alloy specific heat has also been calculated.
The Mechanisms of Cavitation Erosion of the Elektron21 Magnesium Alloy
Authors: Dybowski Bartłomiej , Szala Mirosław , Kiełbus Andrzej , Hejwowski Tadeusz
Published: April 2015

Magnesium and its alloys may be applied as cathodic protection for steel constructions. As the protectors work in water environment, one of the main degradation factors is cavitation erosion. The paper presents results of research on the cavitation erosion of magnesium casting alloy – Elektron 21. The cavitation erosion tests were performed using vibratory apparatus. After the cavitation tests eroded surface and the cross-sections of the specimens were observed by means of scanning electron microscopy. Elektron 21 did not exhibit distinct incubation period of cavitation erosion. The cavitation pits are observed mainly in the α-Mg solid solution grains and on the interfaces between intermetallic phases and the α-Mg. On the other hand, the Mg3(Nd, Gd) eutectic phases are more resistant to cavitation erosion than α-Mg. They are protecting the solid solution from degradation. However, due to their high hardness they undergo cracking and detachment of from the surface. After longer times of cavitation tests, cracks begin to propagate into the material, which leads to crushing of bigger parts of the material.
Reading Matthew 13 as a prophetic discourse: The four parables presented in private
Authors: Scholtz Jacob J.
Published: April 2015

The task of Jesus’ disciples might be to juxtapose ‘new and old’ unconditional prophecies of the kingdom of heaven. After describing its setting, the four parables in Matthew 13, presented in private, are considered from a pre-millennial perspective. The parable of the hidden treasure may indicate how Jesus Christ first authenticates and then hides his authority and power to rule as King in terms of the Davidic Covenant over the literal Davidic kingdom – before he then goes to the cross. Having been to the cross, the parable of the pearl merchant may show how the first, spiritual phase of the kingdom commences when Christ Jesus starts his pearl ministry as High Priest in terms of the New Covenant. The parable of the dragnet has in view the transition from the spiritual phase of the kingdom into its future phase. An overview of the four privately given parables of Matthew 13 is then provided. After this a summary of the new and old prophecies contained in the eight parables of Matthew 13 is presented, followed by the conclusion.’n Ondersoek na Matteus 13 as ’n profetiese diskoers: Die vier gelykenisse wat privaat aangebied is. Die taak van Jesus se dissipels sou kon wees om ‘nuwe en ou’ onvoorwaardelike profesieë van die koninkryk van die hemele met mekaar te vergelyk. Nadat die konteks beskryf is, word die vier gelykenisse in Matteus 13 wat privaat aangebied is vanuit ’n pre-millenniale perspektief oorweeg. Die gelykenis van die verborge skat sou kon aantoon hoe Jesus Christus sy gesag en mag om as Koning in terme van die Dawidiese Verbond oor die letterlike Dawidiese koninkryk te regeer, eers bevestig en dan verberg – waarna Hy kruis toe gaan. Nadat Hy gekruisig is, sou die gelykenis van die pêrelkoper kon aantoon hoe die eerste, geestelike fase van die koninkryk ’n aanvang neem as Christus Jesus sy pêrelbediening as Hoëpriester in terme van die Nuwe Verbond begin. Die gelykenis van die net toon die oorgang van die geestelike fase van die koninkryk van die hemele na die toekomstige letterlike fase. ’n Oorsig oor die vier gelykenisse van Matteus 13 wat privaat aangebied is, word dan verskaf. Daarna word ’n opsomming van die nuwe en ou profesieë wat die agt gelykenisse van Matteus 13 bevat gegee, gevolg deur die slot.
Deus ex Machina? Religious texts, spiritual capital and inequalities: In continuation of a current debate (a response to colleague Farisani)
Authors: Lombaard Christo
Published: April 2015

Often, theological debates stand in the tension between idealist and realist perspectives. This is true too of a discussion in which I have participated on the Africanisation or contextualisation or relevance of the Bible in (South) Africa. In this debate I have at times been cast as being opposed to such Africanisation or contextualisation or relevance. Such criticism is mistaken. I am, however, critical of too idealistic views on the ways in which Old Testament research can impact African problems. In an interdisciplinary manner, the sociological concept of spiritual capital proves useful in illustrating my view. With this, I hope to be understood correctly and, more importantly, to contribute to greater realism concerning the relationship between research and societal problems. In that way, the Africanisation or contextualisation or relevance of the Bible in (South) Africa can become a greater reality. This is of increased importance in the post-secular time frame in which we currently find ourselves, in which the role of religion in the public sphere is again finding greater acceptance rather than being side-lined. On all counts, thus, the plight of the marginalised may be better served. Such broader acceptance of religion also demands that Bible scholarship takes full cognisance of the societal processes through which such upliftment can occur in reality. Therefore, en route to publication, this contribution is presented for critical consideration in three intellectual fora:��The Religious and Spiritual Capital session, XVIIIth International Sociological Association World Congress of Sociology (conference theme: �Facing an unequal world�), Yokohama, Japan, 13�19 July 2014.� The Old Testament Society of South Africa Annual Conference (conference theme: �Studying the Old Testament in South Africa, from 1994 to 2014 and beyond�), University of Johannesburg, 03�05 September 2014.� The Research Day of the Department of Biblical and Ancient Studies, University of South Africa, 25 September 2014, at which colleague E. Farisani�s University of South Africa inaugural lecture of 03 September 2013, �Dispelling myths about African biblical hermeneutics: The role of current trends in African biblical hermeneutics in the post-apartheid South Africa� was re-presented as �Current trends and patterns in African Biblical Hermeneutics in postapartheid South Africa: Myth or Fact?� for the purpose of critical discussion.Intradisciplinary and/or interdisciplinary implications: The intersection of Theology and Sociology adds concrete avenues for furthering the cause of the Africanisation of Biblical Studies.
A note on Lyapunov exponents of deterministic strongly mixing potentials
Authors: Bourgain Jean , Bourgain-Chang Eric
Published: April 2015

In this Note, we consider 1D lattice Schrödinger operators with deterministic strongly mixing potentials as studied in [3] and [2] with very small coupling. We describe a scheme to establish positivity of the Lyapunov exponent from a statement at some fixed scale. The required input may then be derived from Furstenberg theory, if the underlying dynamics are sufficiently mixing, or verified directly by numerical means.
Anderson localization for the almost Mathieu operator in the exponential regime
Authors: Liu Wencai , Yuan Xiaoping
Published: April 2015

For the almost Mathieu operator

(H_{\lambda,\alpha,\theta}u)_n=u_{n+1}+u_{n-1}+2\lambda \mathrm {cos}2\pi(\theta+n\alpha)u_n,

Avila and Jitomirskaya verify this for

|\lambda| > e^{{\frac{16}{9}} \beta}

. In the present paper, we extend their result to the regime

|\lambda| > e^{\frac{3}{2} \beta}

.
Resolvent and propagation estimates for Klein–Gordon equations with non-positive energy
Authors: Georgescu Vladimir , Gérard Christian , Häfner Dietrich
Published: April 2015

We study in this paper an abstract class of Klein-Gordon equations:

\partial_{t}^{2}\phi(t)- 2\mathrm i k \partial_{t}\phi(t)+ h \phi(t)=0,

where

\phi: \mathbb R \to \mathcal H

,

\mathcal H

is a (complex) Hilbert space, and

h

,

k

are self-adjoint, resp. symmetric operators on

\mathcal H

.

We consider their generators

H

(resp.

K

) in the two natural spaces of Cauchy data, the
energy
(resp.
charge
)
spaces
. We do not assume that the dynamics generated by

H

or

K

has any positive conserved quantity, in particular these operators may have complex spectrum. Assuming conditions on

h

and

k

which allow to use the theory of selfadjoint operators on
Krein spaces
, we prove weighted estimates on the boundary values of the resolvents of

H

,

K

on the real axis. From these resolvent estimates we obtain corresponding propagation estimates on the behavior of the dynamics for large times.

Examples include wave or Klein-Gordon equations on asymptotically euclidean or asymptotically hyperbolic manifolds, minimally coupled with an external electro-magnetic field decaying at infinity.
On fluctuations and localization length for the Anderson model on a strip
Authors: Binder Ilia , Goldstein Michael , Voda Mircea
Published: April 2015

We consider the Anderson model on a strip. Assuming that potentials have bounded density with considerable tails we get a lower bound for the fluctuations of the logarithm of the Green’s function in a finite box. is implies an effective estimate by exp(

CW^2

) for the localization length of the Anderson model on the strip of width

W

. The results are obtained, actually, for a more general model with a non-local operator in the vertical direction.
Climatological characteristics of raindrop size distributions within a topographically complex area
Authors: Suh S.-H. , You C.-H. , Lee D.-I.
Published: April 2015

Abstract. Raindrop size distribution (DSD) characteristics within the complex area of Busan, Korea (35.12° N, 129.10° E) were studied using a Precipitation Occurrence Sensor System (POSS) disdrometer over a four-year period from 24 February 2001 to 24 December 2004. Average DSD parameters in Busan, a mid-latitude site, were compared with corresponding parameters recorded in the high-latitude site of Järvenpää, Finland. Mean values of median drop diameter (D0) and the shape parameter (μ) in Busan are smaller than those in Järvenpää, whereas the mean normalized intercept parameter (Nw) and rainfall rate (R) are higher in Busan. To analyze the climatological DSD characteristics in more detail, the entire period of recorded rainfall was divided into 10 categories with different temporal and spatial scales. When only convective rainfall was considered, mean Dm and Nw values for all these categories converged around a maritime cluster, except for rainfall associated with typhoons. The convective rainfall of a typhoon showed much smaller Dm and larger Nw compared with the other rainfall categories. In terms of diurnal DSD variability, we observe maritime (continental) precipitation during the daytime (DT) (nighttime, NT), which likely results from sea (land) breeze identified through wind direction analysis. These features also appeared in the seasonal diurnal distribution. The DT and NT Probability Density Function (PDF) during the summer was similar to the PDF of the entire study period. However, the DT and NT PDF during the winter season displayed an inverse distribution due to seasonal differences in wind direction.
The dark side of risk and crisis communication: legal conflicts and responsibility allocation
Authors: Scolobig A.
Published: April 2015

Abstract. Inadequate, misinterpreted or missing risk and crisis communication may be a reason for practitioners, and sometimes even science advisors, to become subjects of criminal charges. This work discusses the legal consequences of communication. After presenting some cases, the discussion focuses on three critical issues: the development of effective communication protocols; the role, tasks and responsibilities of science advisors; and the collateral effects of practitioners' defensive behaviours. For example, if the avoidance of personal liability becomes a primary objective for practitioners, it may clash with other objectives, such as the protection of vulnerable communities or the transparency of decision-making. The conclusion presents some ideas for future research on the legal aspects of risk communication.
Liver Transplantation for Patients with Portopulmonary Hypertension: a Case Report and Review of the Literature
Authors: Macas Andrius , Kupčinskas Limas , Barauskas Giedrius , Trepenaitis Darius , Kupčinskas Juozas , Petkevičiūtė Aurelija , Mačiulienė Asta
Published: April 2015

Portopulmonary hypertension is one of the complications for people with end stage chronic liver disease. This condition occurs to 5-8% of people, who need liver transplantation, and it causes a higher risk of perioperative complications or these patients are even banned from this procedure. Therefore, it is very important to diagnose this pathology in time using right heart catheterization and provocative volume and dobutamine samples for evaluation of the right ventricle function. Fortunately, adequate medical treatment with its most important part – vasodilator drugs - cures portopulmonary hypertension or lowers the perioperative risk caused by this condition. This case report presents a 50-year-old male hospitalized for liver transplantation. The patient has cirrhosis of the liver caused by hepatitis C, liver failure and portopulmonary hypertension. He has been taking vasodilator drugs for almost 8 months in order to prepare for a surgical treatment and when the operation’s day came, all tests needed including echocardiography shown that the transplantation could be performed. During the operation patient’s heart function was monitored with transesophageal echocardiography. Even though the mean pulmonary arterial pressure was marginal, the operation was successful and the patient could be extubated right after the procedure. Systolic pulmonary arterial pressure of the recipient dropped from 70 mmHg to 60.
Rapid Group a Streptococcus Antigen Test (Radt) Usage and Expediency in Diagnosis and Treatment of Pharyngotonsillitis in Family Physician Practice
Authors: Augulytė Agnė , Čepanauskas Povilas , Simanauskas Kazys
Published: April 2015

Background. Group A streptococcus (S. pyogenes) is responsi- ble for 5 – 20% of cases of pharyngitis in adults and 15 to 20% of cases in children. Most common diagnostic tests are throat culture and rapid antigen detection testing (RADT). The modified Centor criteria can be used to help physicians decide which patients need no testing, throat culture/rapid antigen detection testing or empiric antibiotic therapy. Objective. Evaluate the rapid group A streptococcus antigen test (RADT) usage and expediency in family physician practice. Goals. To analyze children aged between 3 - 15 who suffers from acute pharyngitis ≥ 3 times per year and have ≥ 3 modified Centor criteria; to evaluate the ease of use of RADT in family phy- sician practice; to identify the correlation between RADT and the clinical symptoms of the acute pharyngitis and between the RADT and the blood test results; to evaluate the importance of RADT in diagnosing the acute pharyngitis and choosing treatment strategy. Methods. The study was accomplished in 2011-2013. 108 children aged between 3 and 15 and who suffers from acute pha- ryngitis > 2 times per year, plus have ≥ 3 modified Centor criteria were investigated. Prospectively all patients were tested by RADT. Also, the prescribed treatment and its effectiveness were analyzed. Statistical facts analysis was performed by using „SPSS 17.0“ and „MS Excel“ programs. Results. Girls suffer more often than boys from acute pha- ryngotonsillitis. The age average of patients was 7,22 ± 3,532. On average, patients appealed to doctor after 2-3 days of illness. RADT was positive in 32 (29.6%) children. Moreover, RADT was more often positive (42%) for children in 7-10 years old group, also for children who had 5 modified Centor criteria (62% of all positive cases). Conclusion. No statistically significant difference was obtained between the clinical symptoms and treatment effectiveness for children with a positive or negative result in RADT. However, all patients with positive RADT and who were taking Phenoxymethyl- penicillin recovered in 10 days. Moreover, obtained data shows that RADT test will facilitate the correct diagnosis and the tactics of selecting the treatment.
Rapid Ultrasound Methods in Anesthesiology and Critical Care Medicine
Authors: Macas Andrius , Mačiulienė Asta , Ramanavičiūtė Sandra , Vilkė Alina , Petniūnas Kęstutis , Mačiulaitytė Evelina , Pundinaitė Kristina , Didžbalytė Jūratė , Deksnys Mindaugas , Trepenaitis Darius
Published: April 2015

The variety of focus assessed ultrasound applications and protocols in emergency department and intensive care unit setting is growing. Focus assessed protocols can provide essential information about critically ill patient. It is now the standard of care to perform focused assessment using sonography for trauma - FAST early in the evaluation of trauma patient. Other focus assessed protocols can prove to be useful as well as FAST.
West African Islamic States and “Antislavery” in The Walking Qur'an
Authors: Robinson David
Published: April 2015

Challenging conventional wisdom about Islam and Muslim societies in West African history, Rudolph “Butch” Ware's The Walking Qur'an: Islamic Education, Embodied Knowledge and History in West Africa is not a conventional study of Islam, nor is it a study of a particular region or time period in African history. Rather, I would call it an intellectual history of selected Muslim leaders and societies in West Africa, but with substantial reference to the foundations of Islam and figures such as Bilal. The focus of the book is Qur'anic education across the centuries, from Mecca to West Africa, although education beyond the Qur'an is often subsumed in that. My fundamental question about the text has to do with the relationship of the “Islamic state,” symbolized especially by Futa Toro, to antislavery.
It's Scripturalization, Colleagues!
Authors: Wimbush Vincent L.
Published: April 2015

Rudolph Ware's fascinating book, The Walking Qur'an, does not address the broader challenges of scripturalization—that is, the process by which a text becomes “scripture” and the powerful interests that this authorizing of text reflects and secures. Why, for example, does Ware's book appeal to a discussion of the classical tradition without addressing the ideologies that such a framing presupposes? Even as it claims a focus on an embodied engagement of Islamic scriptures in West Africa, Ware's book nonetheless fetishizes the text. It is an apologetic that does not address how, through the mimetic (scripturalizing) practices that are managed by the regime of scripturalization, people in West Africa and peoples throughout the world have manipulated their own and others’ imaginations and have been manipulated in turn. This critique is a challenge to a different type of critical orientation—to social formation and human-making.
Embodied Knowledge and The Walking Qur'an:
Authors: Seesemann Rüdiger
Published: April 2015

More than a study of Qur'an schooling in Senegambia, Rudolph Ware's The Walking Qur'an offers a new reading of West African history and a compelling argument about Islamic epistemologies. According to Ware, the embodied knowledge practices preserved in Senegambian Qur'an schools up to the present day have their roots in the early days of Islam. This article focuses on Ware's intervention in the debate about epistemology and engages with his distinction between embodied knowledge, which he uses to characterize the knowledge practices in the Qur'an schools, and disembodied knowledge, which Ware sees as predominant among modern Muslims. Expanding on Ware's exceptional study, the article argues that the embodied knowledge paradigm is closely connected to a wider Islamic tradition that can be labeled the Maliki-Ash'ari complex. Further, the article raises questions about Ware's depiction of the disembodied knowledge paradigm and calls for further research into Salafi epistemology.
Interfaith Resistance in South Africa
Authors: Lubbe G. J. A.
Published: April 2015

This edited excerpt from the Rev. Dr. G. J. A. Lubbe's memoirs, titled Embraced by Grace: The Story of a White Ant, describes the formation and impact of the nonviolent interfaith movement against apartheid in South Africa. From 1984 to 1994, the year of President Nelson Mandela's election, Lubbe led the South African chapter of the World Conference on Religion and Peace, now known as Religions for Peace. Under its organizational umbrella South Africans of various faiths crossed both theological and racial lines to oppose apartheid and later to influence the interfaith ethos of postapartheid South Africa.
Evaluación de la integración relacional de los inmigrantes en uniones mixtas a partir del análisis de redes personales
Authors: De Miguel Luken Verónica , Lubbers Miranda J. , Solana Solana Miguel , Rodríguez-García Dan
Published: April 2015

Desde principios de la última década el número de matrimonios mixtos ha crecido considerablemente. En este artículo presentamos resultados que intentan clarifi car la relación entre uniones mixtas e integración social, a partir del análisis de datos primarios de entrevistas en profundidad con delineación de redes personales. Los resultados sobre composición y estructura de las redes muestran una presencia más numerosa de españoles en las redes de uniones mixtas, en gran parte familiares agregados por la pareja, que se incorporan antes y tienen más vínculos con otros inmigrantes. Sin embargo, el papel de la pareja española no es más central que el de la inmigrada, ni la proximidad emocional a los autóctonos es mayor en el caso de las uniones mixtas. Los análisis de dos redes particulares sugieren procesos diversos y complejos en la confi guración de los entramados de relaciones en el destino.
¿Somos más móviles incluyendo a la mitad invisible? Análisis de la movilidad social intergeneracional en España en 2011
Authors: Fachelli Sandra , López-Roldán Pedro
Published: April 2015

El objetivo del artículo es presentar los resultados obtenidos en una investigación sobre la movilidad ocupacional intergeneracional en España utilizando la Encuesta de Condiciones de Vida del INE del 2011.

Se compara la ocupación entre origen (padres) y destino (hijos), que tradicionalmente se ha realizado con la población masculina, proponiendo responder la siguiente pregunta: ¿en qué medida los resultados de los análisis sobre movilidad relativa en España cambian al tomar a la población femenina tanto en origen como en destino? Como resultado mostramos que la inclusión de las mujeres en los modelos de movilidad cambia la conclusión habitual sobre la fl uidez constante en el tiempo: existe una mayor fl uidez, no invariante en el tiempo, que revela el nuevo papel que la mujer ha ido adquiriendo en nuestra sociedad en las últimas décadas.
The market for hospital medicine in Denmark
Authors: Hostenkamp Gisela
Published: April 2015

Pharmaceutical expenditure growth has outpaced GDP and healthcare expenditure growth rates in Denmark as in most OECD countries for the last decade. A major part of this increase was due to high growth rates in specialist areas that are typically located in hospital settings. Yet the market for hospital medicines and their procurement are still poorly understood. The present paper characterises the market for hospital medicines in Denmark in terms of its organisation and developments between 2005 and 2009. In Denmark hospital medicines are publicly financed and procurement is centrally organised. 98% of all medicines administered at Danish public hospitals are purchased through a public procurement agency by means of public tenders. Using data on actual contract prices we decompose pharmaceutical expenditure growth into the contributions from newly introduced medicines, price and volume increases and use summary statistics to compare market performance in both sectors. The market for hospital medicine is more concentrated than the pharmaceutical retail sector and the share of generics and parallel imported products is significantly lower. Between 2005 and 2009 expenditures for hospital medicines more than doubled -accounting for almost 40% of the total Danish pharmaceutical market in 2009. Price increases however - although positive and higher than in the pharmaceutical retail sector - were only moderate. The majority of the expenditure growth was due to an increase in utilisation and the introduction of new medicines in the hospital sector. Centralised tendering may therefore have important implications for competition and industry structure in the long run.
Physical activity and child health: Can school-based intervention make a difference?
Authors: Quinto Romani Annette
Published: April 2015

AbstractChildhood obesity and inactivity is a significant public health problem that also has economic consequences. Therefore, economists have a role to play in determining the causal impacts. The influences of childhood background on outcomes can, usefully, be broken down into the effect of family, school and peer. To combat the raising childhood obesity, schools have been advocated as a potential area. This paper analyses whether increasing physical activity in a school context can contribute to health improvement using multiple outcomes. We address the issue by using a unique longitudinal data set of, respectively, 1087 (BMI) and 1047 (fitness) schoolchildren attending 37 state schools in the Municipality of Aalborg, Denmark. The effect is identified by using a randomized experiment that creates an exogenous increase in physical activity. Surprisingly, we find that the intervention did not have the expected impact on schoolchildren’s health, and the scant evidence we have points towards a negative effect. A plausible explanation is that the results mask important heterogeneity. Another plausible explanation is that the results also capture any compensating behaviour that schoolchildren engage in by being less active out of school. From a public-policy perspective, increasing physical activity in a school context seems to increase the ‘gap’ in child health and ‘crowd-out’ outside-school physical activity. Consequently, a supportive cost-benefit case might exist if parental behaviour is assumed to be affected by school resources and endogenous.