bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic Emission Monitoring during Static Modulus Elasticity Test of Concrete Specimen
Authors: Topolář Libor , Pazdera Lubos , Cikrle Petr
Published: December 2013

Acoustic emission method is often used to detect a failure at a very early stage of damage long before a structure completely fails. The paper presents experiment focused on analysing acoustic emission signals captured during commonly used static modulus elasticity test of specimens of concrete. Quantitative acoustic emission techniques were used to measure micro fracture properties. For three different concrete mixtures typical acoustic emission patterns were identified in the acoustic emission records to further describe the under-the-stress behaviour and failure development. Although we are able to predict failure loads and damage patterns to some extent, we still do not have a good understanding of the relationships between micro structural phenomena and the corresponding effects on macroscopic behaviour. It logically follows that if we have a better understanding of the relationships between micro structural events and macroscopic behaviour, we will be in a better position to formulate predictive models for large-scale structural performance and reliability. An understanding of microstructureperformance relationships is the key to true understanding of material behaviours. Since we know that material microstructure influences its properties, and that cement-based materials of different microstructure have different failure properties and then the variations in micro fracture phenomena must be manifested in the acoustic emission response of the different specimens.
Permeability and Basic Physical Properties of Concrete with Metakaolin Addition
Authors: Reiterman Pavel , Keppert Martin , Čáchová Monika , Holčapek Ondřej , Vogel Filip , Kolář Karel , Konvalinka Petr
Published: December 2013

Surfacing, concrete mixture composition and curing are of great importance for the concrete surface resistance. Thats the reason, why many leading experts agree on the importance of monitoring the concrete skin as the most loaded area affected by the external environment. Many research works demonstrate that application of metakaolin improves properties of concrete as freeze-thaw resistance and resistance against de-icing salts with freeze-thaw cycles combination. A very important role in concrete performance in such severe environment is played by porous system and surface of hardened concrete. The paper introduces an experimental program focused on the monitoring of water transport in surface layer of fair-face concrete aimed at monitoring the permeability of concrete, since concrete permeability is a property uniquely affecting durability of concrete. These methods are complemented by experimental results and other traditional tests. These findings will serve to further optimization of the structure being created, thus ensuring its better aesthetic and functional characteristics.
Influence of Humidity on the Material Properties of Cement Paste with Fly Ash in the Mutual Relation 50/50
Authors: Padevět Pavel , Zobal Ondřej
Published: December 2013

The different properties of building materials are often caused by their varying humidity respectively water saturation levels. The cement paste is a porous material. The cement paste mixed with fly ash is highly porous material whose properties depend on the amount of pores in the material and the state of saturation. Basic material properties like strength, Modulus of elasticity, volume weight are compared in article for cement paste with fly ash for two states, saturated and dried materials. The ratio of cement and bulk ash was 1:1. Article presents results of experiments in age of 1 month after production.
A Modified Strip Method to Speed up the Calculation of Normal Stress between Wheel and Rail
Authors: Lack Tomáš , Gerlici Juraj
Published: December 2013

An important parameter influencing the power effect of a wheel on the rail is the size and shape of the contact area as well as the normal stress distribution which has the impact on it. Nowadays various methods are used to find out the size of contact areas and stresses [. It is necessary to mention the Hertz method as one of the oldest up to date used methods. It provides acceptable results for a large area in spite of many simplifications. Another computational procedure is the Kalker variation method [ or the strip method [ which is, thanks to its results, close to reality and is used in the following calculations. Nowadays, another group of calculation program systems (ANSYS, ADINA) is used in certain situations. The systems work on the base of finite elements method theory.
Experimental Tests of the UHPC in Triaxial Compression
Authors: Vogel Filip , Sovják Radoslav , Jogl Marcel
Published: December 2013

An experimental study of the ultra high performance concrete (UHPC) subjected to triaxial compression is presented in this paper. The examined ultra high performance concrete was developed at the Faculty of Civil Engineering at CTU in Prague from the components locally available in the Czech Republic without using any special mixing technique or curing procedure. The uniaxial compressive strength was determined to be 123 MPa and 149 MPa for cylinders and cubes, respectively. Behaviour of the UHPC in triaxial compression was investigated in two different ways. In the first way cylinders were tested in triaxial chamber. The cylinders were 200 mm high and 100 mm in diameter. The cylinders were tested in triaxial chamber under lateral stresses equaled to 10, 20 and 30 MPa. The second way of testing UHPC in the triaxial compression was a triaxial loading machine where cubes were tested. The size of the cubes was 100 mm. The cubes were tested under the lateral stresses equaled to 15, 30, 60 and 90 MPa. Two equations for both cylinders and cubes showing the strength development were provided using power law regressions. The difference between triaxial strength development of cubes and cylinders was slight. The results obtained in this study were in good agreement with the results gained from the literature. It was experimentally verified that the strength development of the UHPC under different levels of the confinement pressure is not linear and tends to follow the power law function. In addition it was stated that the permissible stress surface of the UHPC falls below the permissible stress surface of the normal strength concretes, especially within the higher confinement pressures.
Effect of Base Parameters on Mechanical Properties of Cement Concrete Pavement Considering Interlayer Contact
Authors: Zhang Yan Cong , Gao Ling Ling , Li Sili
Published: December 2013

Three-dimensional structure model on Winkler foundation considering inter layer contact status was established. The effect that base modulus, thickness and inter layer contact status between slab and base to maximum stress of slab bottom and base bottom, shear stress between slab and base, warping of slab was calculated. The results showed that: interlayer contact status had great influence on slab stress and warping. Maximum stress of slab bottom dropped while bonding status decreased and slab warping increased obviously while bonding status weakened. Base modulus was the primary factor for base stress. Maximum stress of base bottom increased while modulus increased, and decreased while bonding status weakened. Interlayer shear stress occurred mainly at slab edge, and decreased while the bonding status weakened, almost had no correlation to base modulus and thickness.
Analysis on Mechanical Reasons for Longitudinal Cracking of Cement Concrete Pavement
Authors: Ma Song Lin , Yue Song , Zhao Zheng Yang
Published: December 2013

This paper, in terms of structure design, mainly considers the unfavorable load position of cement concrete pavements and the finite element software is used to establish three-dimensional solid model for analysis and calculation of load stress. The results show that fatigue stress along the transverse direction is much larger than that along the longitudinal direction, and slabs are most likely to have cracking along the longitudinal direction under the combined effect of load and temperature. It is of certain significance for the prevention of longitudinal cracking of concrete pavements and the extension of pavement life.
A Rapid Method to Determine Joint Opening in JPCP for Sealant Fatigue Test
Authors: Zhang Zhi Geng , Cheng Guo Yi
Published: December 2013

To determine the joint opening value and vertical deflection value for sealant fatigue test, a rapid calculation method was established based on the analysis of factors ( such as temperature gradient, foundation stiffness, slab geometry) effects on joint opening and corner deflection. Then prediction equations were applied with the field collected year-round temperature field in concrete pavement. Probability distributions of half-horizontal displacement and corner vertical deflection exhibit bimodal effect and single peak effect, respectively.
Experimental Investigation of the Shrinkage Performance of Small Blocks Made by Rock Chips Concrete
Authors: Yuan Jie , Feng De Min , Liu Fu Ming , Zhang Yong Quan , Liu Yang
Published: December 2013

A new type of small concrete blocks with high strength performance was generated in this study, and the main component of this kind of small blocks were made by the MU15.0 that was extracted from the waste rock chips. The effect of content of stone powder and the different curing methods on the shrinkage of the proposed concrete blocks, was investigated by using the experimental method. The results showed that (i) with the increase of the amount of stone power, the drying shrinkage of rock chips concrete went up at first, and then the opposite change was generated; (ii) The small hollow blocks made by the rock chips concrete after steam curing kiln, under the condition of enough water curing and seal environment, had higher compressive strength and smaller shrinkage comparing with other curing methods.
Studies on Exciting the Activity of Waste Glass Powder by Hydrothermal Activation
Authors: Kong Qing Qiu , Ke Guo Jun , Wang Dan
Published: December 2013

The effect of hydrothermal activation indifferent temperature and pressure conditions on the pozzolanic activity of waste glass powder was discussed. The waste glass powder was treated at 108°C, 0.15MPa, 116°C, 0.18MPa and 121°C, 0.2MPa for 2h in an autoclave respectively after milling to 4215cm2/g. Mortar was made with untreated and hydrothermal activated waste glass power replacement of cement at 20% respectively, then tested for compressive strength at 3, 7, 14 , 28 and 90 days. Results showed that compressive strength of cement mortar had varying degrees of decline when replacing cement with untreated waste glass powder, comparing to the control one. Decline amplitude was large at early age and small at late age. Activity of waste glass powder was significantly improved after hydrothermal treatment. Compressive strength of mortar improved as temperature and pressure elevated, obtaining optimal strength at 121°C, 0.2MPa. Compressive strength of mortar with hydrothermal activated glass powder was higher than that with untreated glass powder at all age with 20% cement replacement. Compressive strength increased 5.3% ~ 13.6% at 3 d, 6.8%~9.7% at 28 d, 9.7% ~ 17.7% at 90 d. The essence of hydrothermal activation was the corrosion of water in the glass.
Effects of Oil Palm Empty Fruit Bunch (OPEFB) Fibre Size on Fracture Toughness of OPEFB Filled Polymer Nanocomposite
Authors: Kamarudzaman Rahilah , Kalam Anizah , Ahmad Nurul Natisya , Razak Noorrul Wahida Abdul , Salleh Z.
Published: December 2013

The effect of oil palm empty fruit bunch (OPEFB) fiber size on the fracture toughness of OPEFB/PP/PPnanoclay composites was investigated. Four fiber sizes ranging from 180 μm, 250 μm, 300 μm, and 355 μm were used to reinforce PP/PPnanoclay composites. The ratio of PP/PPnanoclay was 7:100 by weight (7 phr). Fracture toughness of the composite was determined according to ASTM D5045 and single edge notch bending (SENB) been employed during the test. The result indicates that the fracture toughness of OPEFB/PP/PPnanoclay composites has decreased as OPEFB fiber size increased. Fracture surfaces investigated through the scanning electron microscopy (SEM) showed that the bonding between fiber and matrix for OPEFB/PP/PPnanoclay composites with smaller OPEFB fibre size has better bonding as compared to OPEFB/PP/PPnanoclay composites with larger OPEFB fiber size.
Mathematical Model to Evaluate Wear Rate of Graphite as Sealing Materials
Authors: Kim Yeon Wook , Kim Jae Hoon , Seo Bo Hwi , Choi Hoon Seok , Park Sung Han , Lee Hwan Kyu
Published: December 2013

The dry sliding wear behavior of graphite (HK-6) that is used as the sealing material to cut off hot gas was evaluated as a function of applied load, sliding speed and temperature. The reciprocating wear tests were carried out at room temperature and elevated temperatures. An attempt has been made to develop a mathematical model by response surface methodology (RSM) and an analysis of variance (ANOVA) technique was applied to confirm the validity of the developed model. Also, the effect of applied load, sliding speed and temperature on wear the behavior of graphite was investigated. The wear mechanism was compared through the observation of the worn surface by SEM analysis. The specific wear rate was dependent on the interaction between temperature, applied load and sliding speed. A developed model can be used to effectively predict the specific wear rate of graphite as a sealing material within the range of variables studied.
Evolutionary Creation of New Molecules
Authors: Osmera Pavel , Rukovansky Imrich
Published: December 2013

We tried to combine the basic principle of grammatical evolution with vortex-ring-fractal structures of atoms to create new molecule structures. This approach combines knowledge of evolutionary optimization with physical chemistry.
The Study of Waste-to-Energy Plant Combustion Characteristics Based on Computational Fluid Dynamics
Authors: Hu Gui Chuan
Published: December 2013

The combustion process for using municipal solid waste as a fuel within a waste to energy plant calls for a detailed understanding of the following phenomena. Firstly, this process depends on many input parameters such as proximate and ultimate analyses, the season of the year, primary and secondary inlet air velocities and, secondly, on output parameters such as the temperatures or mass fraction of the combustible products. The variability and mutual dependence of these parameters can be difficult to manage in practice. Another problem is how these parameters can be tuned to achieving optimal combustible conditions with minimal pollutant emissions, during the plant-design phase. In order to meet these goals, a waste-to-energy plant with bed combustion was investigated by using computational fluid-dynamics approach.
Artificial Immune Systems with Negative Selection Applied to Health Monitoring of Aeronautical Structures
Authors: Parra dos Anjos Lima Fernando , Chavarette Fábio Roberto , dos Santos e Souza Adriano , Silva Frutuoso de Souza Simone , Martins Lopes Mara Lúcia
Published: December 2013

In this paper we present a system for aircraft structural health monitoring based on artificial immune systems with negative selection. Inspired by a biological process, the principle of discrimination proper/non-proper, identifies and characterizes the signs of structural failure. The main application of this method is to assist in the inspection of aircraft structures, to detect and characterize flaws and decision making in order to avoid disasters. We proposed a model of an aluminum beam to perform the tests of the method. The results obtained by this method are excellent, showing robustness and accuracy.
Double Crossed Step-Down-Stress Accelerated Life Testing for Pneumatic Cylinder Based on Cumulative Damage Model
Authors: Chen Juan , Li Jia , Wang De Yi , Fan Dian Liang , Qi Xiao Ye
Published: December 2013

Double Crossed Step-Down-Stress Accelerated Life Testing (DCSDS-ALT) discussed in this paper was implemented by switch down the double stresses alternately. Compared to constant stress test, step-stress test decreased specimen numbers, time and cost, and eventually well improve the accelerated testing efficiency. For pneumatic cylinder, the step-down-stress testing failure physics can be described as cumulative degradation model. By use of cumulative damage General Log-Linear relationship and Weibull assumption, the failure data obtained were equivalently converted to failure data under constant stress testing. Then the reliability specifications can be derived with better accuracy. The 5% of average lifetime estimation error and 1.85% of the characteristic lifetime error are very satisfying for pneumatic industrial lifetime prediction.
Research on Electrical Transmission System with Hydraulic Coupler
Authors: Su Ming , Xi Zhong Ping , Zhu Dong Min , Gu Zhong Chang , Wang Heng
Published: December 2013

In this paper, a simulation model of the electrical transmission system with hydraulic coupler is established based on the analysis of the mechanical characteristics of the motor, the original characteristic curves of the hydraulic coupler and the torque equations of the pump wheel and the turbine. The starting and impact process of the system are simulated and the results reveal the mechanism of the characteristics of the starting process of the system and the isolation effect of the torsional vibration of the hydraulic coupler.
A Study on Penetration Characteristics Test and Analysis of Tungsten Penetrator
Authors: Lee Sang Won , Lee Young Shin , Kim Jae Hoon , Bae Yong Woon , Park Jong Min
Published: December 2013

In this paper, the penetration characteristic of tungsten penetrator was studied. Tungsten and aluminum was used as the material of the penetrator and target, respectively. Dimensions of the aluminum target were 100 X 100 X 5 (mm3). The penetrator with cylinder conical tip and flat tip was used in the impact test and simulation. The range of the initial velocity was from 400 to 1600 m/s. The angle of the incidence on the penetrator with cylinder cone tip was 0 ̊. The angle of the incidence on the penetrator with flat tip was 0 ̊, 30 ̊ , 60 ̊ . To obtain results of the simulation, AUTODYN 3D code was used. The residual mass and velocity was obtained to compare with results between the impact test and simulation.
Pulsed Cathodoluminescence of ZnWO4:Eu Single Crystals and Nanocrystals
Authors: Lisitsyn Viktor M. , Valiev Damir , Tupitsyna Irina A. , Polisadova Elena F. , Lisitsyna Ludmila A. , Andryuschenko Lubov , Dubovik Aleksander , Yakubovskaya Anna , Vovk Oleg
Published: December 2013

Pulsed cathodoluminescence of zinc tungstate samples doped with europium in the form of single crystals and nanocrystals in the transparent organosilicic matrix is studied. The effect of the size of the crystal on spectral and kinetic parameters of the oxygen luminescence centers is interpreted within the model of self-organization of activator nanodefects during crystal growing.
Measuring the Force Gradient Acting on a Magnetic Microsphere above a Micro-Magnet Array
Authors: Ponomareva Svetlana , Zanini Luiz Fernando , Dumas-Bouchiat Frédéric , Dempsey Nora M. , Givord Dominique , Marchi Florence
Published: December 2013

The attractive action exerted by an array of micro-magnets on a single polystyrene microsphere containing superparamagnetic iron oxidenanoparticles, the microsphere constituting a model for cells functionalised with such nanoparticles, have been studied in air by using magnetic force microscopy. For this purpose, the method of gluing a magnetic microsphere to an AFM tip has been developed. Using this custom-made colloidal probe, the regions of the micro-magnet array that act as magnetic traps for the magnetic microsphere have been localized and the long-range trap-sphere interactions have been recorded, measured and compared with simulations.
Surface Acid-Base Characteristics and their Contribution to Aggregative Stability of Nanoparticles
Authors: Yunda Elena , Godymchuk Anna Yu. , Kosova Natalia I. , Kuznetsov Denis V. , Senatova Svetlana
Published: December 2013

Toxicant properties of nanoparticles are influenced by their dispersiveness, catalytic activity, aggregation and dissolution properties, which are determined by acid-base properties of the surface. This paper provides the experimental results of the research of surface acid-base characteristics for pH = 2.0...9.0, and takes into account their contribution to aggregative activity of Zn and ZnO nanoparticles in suspensions with pH = 4.0, 6.0, and 8.0. The maximum value of adsorption capacity can be expected in acid medium for Zn nanoparticles, and in base medium for ZnO nanoparticles. This study showed that when the value of pH is different from 6, suspension aggregative stability was strengthened or weakened for Zn and ZnO nanoparticles, respectively. The conclusion concerning the contribution of nanoparticles adsorption activity which is changed by surface acid-base characteristics to aggregative stability of particles of different compounds has been made.
Strengthening of Foam Glass Materials
Authors: Kazmina Olga , Semukhin Boris , Elistratova Anna
Published: December 2013

Experimental data on strengthening of foam glass materials is presented. A new mechanism of strengthening is proposed which involves formation of amorphous matrix nanoglobules. Highlights: nanospheroid occurrence in foam glass; new strengthening mechanism of amorphous materials; correlation between micro-structural changes in the interpore partition of porous materials and mechanical characteristics thereof.
The Preparation and Properties Study of the Zirconia Dispersion-Strengthened Platinum Materials
Authors: Tang Hui Yi , Wu Bao An , Liu Qin Bin , Zhai Bu Ying , Chen De Mao , Wang Jian Sheng , Luo Feng Lan , Chen Xing Han
Published: December 2013

s: The zirconia dispersion-strengthened platinum thermocouple materials were successfully fabricated by powder metallurgic method. It was studied the zirconia grains influences on platinum materials. The results of the study show that its density is 21.4g/cm3 and its relative density is 99.8%. Its tensile strength obvious overtop pure platinum, the maximum tensile strength is 930MPa. The cures of tensile strength with the processing rate improved of the materials obey a analogy-linear law. The resistance ratio (R100/R0)1.3922, and thermal electromotive force of Pt matched PtRh10 meet I measuring accuracy grade relative to GB/T1598-2010 stander.
Effect of the Precipitated Second Phase during Aging on the Damping Capacity Degradation Behavior of M2052 Alloy
Authors: Zhang Ying , Li Ning , Yan Jia Zhen , Xie Jin Wu
Published: December 2013

In this study, the damping capacity degradation in Mn-20Cu-5Ni-2Fe alloy (M2052) aged at 435 °C for 2-24 hours was investigated. The damping capacity was measured by a torsion pendulum. XRD, SEM and EDS analysis methods were used to characterize the microstructure of specimens. The results showed that aging at 435 °C for more than 4 h leaded to the precipitation of α-Mn in the matrix of M2050, which resulted in the decrease of the original damping capacity. Holding the aged samples in 60°C environment, the damping capacity of under-aged and peak-aged M2052 samples decreased rapidly with the time increasing. While no obvious degradation of damping capacity occurred in the over-aged sample even after 40 d, which is probably due to the precipitation of α-Mn phase in the matrix of alloy. M2050 alloy with high and stable damping capacity can be obtained by aging at 435°C for 8 h.
Study on Synthesis and Property of Anti-Salt Super Absorbent Resin
Authors: Jiang Shan Quan , Sun Xiang Wei , Xie Zhao Xia , Qin Long
Published: December 2013

The maleic acid ( MA )2-acrylamido-2-methylpropanesulfonic acid (AMPS) and acrylamide (PAMPS/AM/MA) superabsorbent copolymer was synthesized by aqueous solution polymerization with ammonium persulfate as initiator,N,N-methylene-bisacrylamide ( NMBA) as crosslinking agent. The influence of pH,mass ratio of AMPS to acrylamide ( AM) ,the amount of crosslinking agent and initiator,and reaction temperature on the absorption capability of water and salt solution were investigated. The results show that the water absorbency of the superabsorbent polymer prepared at the optimum condition in deionized water and in 0.9% NaCl solution is about 235 and 132g/g,respectively,and under the same conditions,the sample has more excellent water absorption and salt-resistance.
Efficient Production of Lactic Acid from Distillers Grains Hydrolysates by Rhizopus oryzae CICC41411
Authors: Ren Hai Wei , Li Jin Ping , Zhang Yi , Li Zhi Zhong
Published: December 2013

Lignocellulosic biomass-derived sugars is considered to be an economically attractive carbohydrate feedstock for large-scale fermentation of bulk chemicals such as lactic acid (LA). The aim of this study was to investigate the possibility of LA production from distillers grains hydrolysates (DGHs) by the Rhizopus oryzae CICC41411 and to optimize the biological conversion of reducing sugar into LA to evaluate the culture conditions. The effects of factors such as nitrogen source, inoculations size, CaCO3 addition, pH value and fermentation time on the lactic acid concentration (LAC) and the reducing sugars utilization rate (RSUR) were researched. The results show that ammonium chloride is the most favorable nitrogen source for LA production by Rhizopus. Oryzae CICC41411, the optimal fermentation conditions are inoculation size of 2.5% seed culture, CaCO3 addition of 80 g·L-1, fermentation time of 96 h and culture pH of 6.0. This study provides an encouraging means of producing LA from lignocellulosic resource such as the low-cost distillers grains.
Comparison of Bulge Test vs. Conical Expansion Test for Hollow Extruded Profile Characterization
Authors: Reggiani Barbara , Segatori Antonio , Donati Lorenzo , Tomesani Luca , Terenzi Alberto , Salice Alberto
Published: December 2013

An experimental campaign on a tubular hollow profile, extruded in industrial environment at two ram speeds, was performed to compare two testing methodologies used for the assessment of the seam welds strength: the cone expansion and the bulge tests. In the former, a cone-shaped punch is driven into the tube causing the expansion till the specimen fracture; in the latter, an internal rubber plug is used to expand the specimen allowing to apply an hydrostatic tensile state. Results and repeatability of the two tests were analyzed in terms of loads and tube radius elongations at fracture; location and morphology of the fracture were also inspected. In each condition, and for both tests, ductile fractures appeared at seam weld location. The bulge test showed a significant reduced data scattering if compared to the cone test and provided more conservative outcomes in terms of elongation at fracture; in addition, it marked more prominently the effect of the increased ram speed that promoted a weld strength decay.
Advanced Frictional Models for Extrusion Application
Authors: Hora Pavel , Becker Christoph , Tong Long Chang , Maier Joachim , Müller Sören
Published: December 2013

During the extrusion processes, very complex adhesion and friction effects between the die surface and the extruded material occur. They have a strong influence on the velocity distribution in the profile, as well as on the life-term behavior of the tools. In the framework of the virtual process modeling usually the Coulomb or the Shear Friction models are applied. The practical experience shows, that those simplified descriptions of the frictional behavior result in poor FEM results. The present work relates to experimentally evaluated tribological behavior of the Torsion-Tribo-test and shows how those data can be transferred to different new friction models.
A New Constitutive Model Describing the Plastic Flow of Metals: Application to the AA6082 Aluminum Alloy
Authors: El Mehtedi Mohamad , El Mohtadi Samer , Spigarelli Stefano
Published: December 2013

A new constitutive relationship based on the combination of the Garofalo and Hensel-Spittel equations has been developed and successfully used to model the plastic flow of a AA6082 aluminum alloy. Two regimes of temperature and strain rate were identified: the constitutive analysis suggested that in the low strain rate/high temperature regime, deformation was controlled by viscous glide of dislocations in atmospheres of Mg solute atoms, while in the high strain rate/ low temperature regime, deformation was controlled by climb.
Anthropogenic agent implicated as a prime driver of shift in precipitation in eastern China in the late 1970s
Authors: Wang T. , Wang H. J. , Otterå O. H. , Gao Y. Q. , Suo L. L. , Furevik T. , Yu L.
Published: December 2013

Abstract. Observation shows that eastern China experienced an interdecadal shift in the summer precipitation during the second half of the 20th century. The summer precipitation increased in the middle and lower reaches of the Yangtze River valley, whereas it decreased in northern China. Here we use a coupled ocean–atmosphere general circulation model and multi-ensemble simulations to show that the interdecadal shift is mainly caused by the anthropogenic forcing. The rapidly increasing greenhouse gases induce a notable Indian Ocean warming, causing a westward shift of the western Pacific subtropical high (WPSH) and a southward displacement of the East Asia westerly jet (EAJ) on an interdecadal timescale, leading to more precipitation in Yangtze River valley. At the same time the surface cooling effects from the stronger convection, higher precipitation and rapidly increasing anthropogenic aerosols contribute to a reduced summer land–sea thermal contrast. Due to the changes in the WPSH, the EAJ and the land–sea thermal contrast, the East Asian summer monsoon weakened resulting in drought in northern China. Consequently, an anomalous precipitation pattern started to emerge over eastern China in the late 1970s. According to the model, the natural forcing played an opposite role in regulating the changes in WPSH and EAJ, and postponed the anthropogenically forced climate changes in eastern China. The Indian Ocean sea surface temperature is crucial to the response, and acts as a bridge to link the external forcings and East Asian summer climate together on a decadal and longer timescales. Our results further highlight the dominant roles of anthropogenic forcing agents in shaping interdecadal changes of the East Asian climate during the second half of the 20th century.
Towards IASI-New Generation (IASI-NG): impact of improved spectral resolution and radiometric noise on the retrieval of thermodynamic, chemistry and climate variables
Authors: Crevoisier C. , Clerbaux C. , Guidard V. , Phulpin T. , Armante R. , Barret B. , Camy-Peyret C. , Chaboureau J.-P. , Coheur P.-F. , Crépeau L. , Dufour G. , Labonnote L. , Lavanant L. , Hadji-Lazaro J. , Herbin H. , Jacquinet-Husson N. , Payan S. , Péquignot E. , Pierangelo C. , Sellitto P. , Stubenrauch C.
Published: December 2013

Abstract. Besides their strong contribution to weather forecast improvement through data assimilation, thermal infrared sounders onboard polar-orbiting platforms are now playing a key role for monitoring atmospheric composition changes. The Infrared Atmospheric Sounding Interferometer (IASI) instrument developed by the French space agency (CNES) and launched by Eumetsat onboard the Metop satellite series is providing essential inputs for weather forecasting and pollution/climate monitoring owing to its smart combination of large horizontal swath, good spectral resolution and high radiometric performance. EUMETSAT is currently preparing the next polar-orbiting program (EPS-SG) with the Metop-SG satellite series that should be launched around 2020. In this framework, CNES is studying the concept of a new instrument, the IASI-New Generation (IASI-NG), characterized by an improvement of both spectral and radiometric characteristics as compared to IASI, with three objectives: (i) continuity of the IASI/Metop series; (ii) improvement of vertical resolution; (iii) improvement of the accuracy and detection threshold for atmospheric and surface components. In this paper, we show that an improvement of spectral resolution and radiometric noise fulfill these objectives by leading to (i) a better vertical coverage in the lower part of the troposphere, thanks to the increase in spectral resolution; (ii) an increase in the accuracy of the retrieval of several thermodynamic, climate and chemistry variables, thanks to the improved signal-to-noise ratio as well as less interferences between the signatures of the absorbing species in the measured radiances. The detection limit of several atmospheric species is also improved. We conclude that IASI-NG has the potential for strongly benefiting the numerical weather prediction, chemistry and climate communities now connected through the European GMES/Copernicus initiative.
Improving accuracy and precision of ice core δD (CH4) analyses using methane pre- and hydrogen post-pyrolysis trapping and subsequent chromatographic separation
Authors: Bock M. , Schmitt J. , Beck J. , Schneider R. , Fischer H.
Published: December 2013

Abstract. Firn and polar ice cores offer the only direct paleoatmospheric archive. Analyses of past greenhouse gas concentrations and their isotopic compositions in air bubbles in the ice can help to constrain changes in global biogeochemical cycles in the past. For the analysis of the hydrogen isotopic composition of methane (δD (CH4)) 0.5 to 1.5 kg of ice was previously necessary to achieve the required precision. Here we present a method to improve precision and reduce the sample amount for δD (CH4) measurements on (ice core) air. Pre-concentrated methane is focused before a high temperature oven (pre pyrolysis trapping), and molecular hydrogen formed by pyrolysis is trapped afterwards (post pyrolysis trapping), both on a carbon-PLOT capillary at −196 °C. A small amount of methane and krypton are trapped together with H2 and must be separated using a short second chromatographic column to ensure accurate results. Pre and post pyrolysis trapping largely removes the isotopic fractionation induced during chromatographic separation and results in a narrow peak in the mass spectrometer. Air standards can be measured with a precision better than 1‰. For polar ice samples from glacial periods we estimate a precision of 2.2‰ for 350 g of ice (or roughly 30 mL (at standard temperature and pressure (STP)) of air) with 350 ppb of methane. This corresponds to recent tropospheric air samples (about 1900 ppb CH4) of about 6 mL (STP) or about 500 pmol of pure CH4.
Can we model observed soil carbon changes from a dense inventory? A case study over England and Wales using three versions of the ORCHIDEE ecosystem model (AR5, AR5-PRIM and O-CN)
Authors: Guenet B. , Moyano F. E. , Vuichard N. , Kirk G. J. D. , Bellamy P. H. , Zaehle S. , Ciais P.
Published: December 2013

Abstract. A widespread decrease of the topsoil carbon content was observed over England and Wales during the period 1978–2003 in the National Soil Inventory (NSI), amounting to a carbon loss of 4.44 Tg yr−1 over 141 550 km2. Subsequent modelling studies have shown that changes in temperature and precipitation could only account for a small part of the observed decrease, and therefore that changes in land use and management and resulting changes in heterotrophic respiration or net primary productivity were the main causes. So far, all the models used to reproduce the NSI data have not accounted for plant–soil interactions and have only been soil carbon models with carbon inputs forced by data. Here, we use three different versions of a process-based coupled soil–vegetation model called ORCHIDEE (Organizing Carbon and Hydrology in Dynamic Ecosystems), in order to separate the effect of trends in soil carbon input from soil carbon mineralization induced by climate trends over 1978–2003. The first version of the model (ORCHIDEE-AR5), used for IPCC-AR5 CMIP5 Earth System simulations, is based on three soil carbon pools defined with first-order decomposition kinetics, as in the CENTURY model. The second version (ORCHIDEE-AR5-PRIM) built for this study includes a relationship between litter carbon and decomposition rates, to reproduce a priming effect on decomposition. The last version (O-CN) takes into account N-related processes. Soil carbon decomposition in O-CN is based on CENTURY, but adds N limitations on litter decomposition. We performed regional gridded simulations with these three versions of the ORCHIDEE model over England and Wales. None of the three model versions was able to reproduce the observed NSI soil carbon trend. This suggests either that climate change is not the main driver for observed soil carbon losses or that the ORCHIDEE model even with priming or N effects on decomposition lacks the basic mechanisms to explain soil carbon change in response to climate, which would raise a caution flag about the ability of this type of model to project soil carbon changes in response to future warming. A third possible explanation could be that the NSI measurements made on the topsoil are not representative of the total soil carbon losses integrated over the entire soil depth, and thus cannot be compared with the model output.
An assessment of the ability of Bartlett–Lewis type of rainfall models to reproduce drought statistics
Authors: Pham M. T. , Vanhaute W. J. , Vandenberghe S. , De Baets B. , Verhoest N. E. C.
Published: December 2013

Abstract. Of all natural disasters, the economic and environmental consequences of droughts are among the highest because of their longevity and widespread spatial extent. Because of their extreme behaviour, studying droughts generally requires long time series of historical climate data. Rainfall is a very important variable for calculating drought statistics, for quantifying historical droughts or for assessing the impact on other hydrological (e.g. water stage in rivers) or agricultural (e.g. irrigation requirements) variables. Unfortunately, time series of historical observations are often too short for such assessments. To circumvent this, one may rely on the synthetic rainfall time series from stochastic point process rainfall models, such as Bartlett–Lewis models. The present study investigates whether drought statistics are preserved when simulating rainfall with Bartlett–Lewis models. Therefore, a 105 yr 10 min rainfall time series obtained at Uccle, Belgium is used as a test case. First, drought events were identified on the basis of the Effective Drought Index (EDI), and each event was characterized by two variables, i.e. drought duration (D) and drought severity (S). As both parameters are interdependent, a multivariate distribution function, which makes use of a copula, was fitted. Based on the copula, four types of drought return periods are calculated for observed as well as simulated droughts and are used to evaluate the ability of the rainfall models to simulate drought events with the appropriate characteristics. Overall, all Bartlett–Lewis model types studied fail to preserve extreme drought statistics, which is attributed to the model structure and to the model stationarity caused by maintaining the same parameter set during the whole simulation period.
The effect of individual phosphate emulsifying salts and their selected binary mixtures on hardness of processed cheese spreads
Authors: Buňka František , Nagyová Gabriela , Salek Richados Nikolaos , Černí­ková Michaela , Bacova Helena , Kráčmar Stanislav
Published: December 2013

The aim of this work was to observe the effects of emulsifying salts composed of trisodium citrate and sodium phosphates with different chain length (disodium phosphate (DSP), tetrasodium diphosphate (TSPP), pentasodium triphosphate (PSTP) and sodium salts of polyphosphates with 5 different mean length (n ≈ 5, 9, 13, 20, 28)) on hardness of processed cheese spreads. Hardness of processed cheese spreads with selected binary mixtures of the above mentioned salts were also studied. Measurements were performed after 2, 9 and 30 days of storage at 6 °C. Hardness of processed cheese increased with increase in chain length of individually used phosphates.  Majority of applied binary mixtures of emulsifying salts had not significant influence on hardness charges in processed cheese spreads. On the other hand, a combination of phosphates salts (DSP with TSPP) was found, which had specific effect on hardness of processed cheese spreads. Textural properties of samples with trisodium citrate were similar compared to samples with DSP.
Genetics of inherited platelet disorders
Authors: Gothwal M. , Sandrock-Lang K. , Zieger B.
Published: December 2013

The current review describes inherited platelet disorders, illustrates their clinical phenotype and molecular genetic defects. Platelets are the key molecules mediating haemostasis via adhesion, activation and clot formation at the site of injury. The inherited platelet disorders can be classified according to their platelet defects: receptor/cytoskeleton defects, secretion disorder, and signal transduction defect.

Patients with inherited thrombocytopathia present with mucous membrane bleedings (epistaxis, gingival bleeding) and may present with serious life threatening bleedings following surgery or trauma. Therefore, biochemical and molecular genetic characterization of inherited platelet disorders is important to understand these disorders and to support an efficient therapy.
Teaching Practical Logic
Authors: Hillier Sam ,   Philosophy Documentation Center
Published: December 2013

I share my experiences teaching Practical Logic with a focus on good reasoning as eliminating alternative conclusions. This unites the various topics traditionally taught in such courses (deductive logic, inductive logic, causal reasoning, probability theory, fallacies, cognitive biases, the scientific method, and creativity) in a way that I have found to be extremely effective.
Herding, Heterogeneity, and Momentum Trading of Institutional Investors Across Asset Classes
Authors: Ben-Horin Moshe , Kedar-Levy Haim
Published: December 2013

This paper examines herding, heterogeneity, and momentum trading of institutional investors in Israel across a broad variety of financial assets. While previous studies typically focus on stocks only, we examine herding patterns, heterogeneity, and momentum trading of institutional investors in five asset classes. We find that during the sample period (1/2002 â€“ 12/2011) large investors tended to herd more than medium and small-size investors. In contrast, small investors used momentum trading patterns more than medium and large-size investors. Homogeneity was found among large investors, especially pension funds, and during the first half of the 2000s, when investors purchased corporate bonds at the expense of government bonds. This phenomenon ended upon the beginning of the subprime crisis and against the backdrop of the financial difficulties of the bond issuers. In those years, panicked investors withdrew funds from the most liquid institutions (study funds), while infusing funds to pension and provident funds due to legally binding arrangements. We attribute some of the heterogeneous trading of the institutional investors, to those factors.
Le rapport entre le juridique et le clinique dans l’application de la Loi sur la protection de la jeunesse : une perspective relationnelle
Authors: Ricard Laurence
Published: December 2013

La protection de la jeunesse est une sous-discipline du droit de la famille qui est peu étudiée par les milieux universitaires du monde juridique. Cependant, une analyse des objectifs de la Loi sur la protection de la jeunesse du Québec montre que les fondements cliniques de la Loi se heurtent souvent au fonctionnement rigide du milieu juridique. Par le biais d’une perspective relationnelle qui explique la nouvelle orientation prise par la Loi depuis les modifications de 2006, l’auteure cherche à montrer que plusieurs caractéristiques du système contradictoire ne sont pas cohérentes avec la nouvelle conception de l’enfant et de l’individu véhiculée par la Loi.
Le contenu explicite de la convention collective, un leurre ?
Authors: Sénéchal Carole
Published: December 2013

Au cours des dix dernières années, un débat houleux s’est engagé au sujet du rapport des diverses sources en droit des rapports collectifs de travail. Devant la multiplication des seuils minima de conditions de travail décrétés par le corpus législatif et la prolifération des instances spécialisées chargées d’en assurer la mise en oeuvre, un des enjeux sous-jacents est de préserver la spécificité du régime collectif nord-américain, qui s’appuie sur les trois piliers historiques que sont le monopole de représentation syndicale, l’existence d’une convention collective applicable à l’ensemble des salariés compris dans l’unité d’accréditation et le recours exclusif à l’arbitrage de griefs pour toute mésentente qui relève de l’application ou de l’interprétation de ladite convention. Cet article se propose d’explorer les diverses implications que soulève cette dynamique renouvelée entre l’essence contractuelle des rapports collectifs et l’ensemble de l’ordonnancement juridique.
Main basse sur le pouvoir dans les sociétés canadiennes. Éclairage sur les finalités et modalités des décisions actionnariales
Authors: Tchotourian Ivan
Published: December 2013

Les actionnaires sont au coeur des discussions et des réformes entreprises dans de nombreux pays à la suite de la crise économique et financière. En effet, la question du renforcement de leur droit de vote et de la facilitation de leur prise de pouvoir dans les sociétés par actions est au centre des réflexions menées par les régulateurs et les spécialistes du droit des sociétés. Dans le cadre de cette étude, nous analysons les deux aspects d’une telle prise de pouvoir actionnariale: sa finalité et ses modalités. En nous servant des illustrations canadiennes et québécoises, nous démontrons que si le droit de vote des actionnaires ainsi que sa mécanique ait été une préoccupation constante des autorités réglementaires canadiennes depuis les années 70, l’intérêt égoïste qu’ils favorisent — à l’inverse de celui que peuvent promouvoir les administrateurs — amène à n’aborder cette option législative qu’avec prudence. Néanmoins, au regard des enjeux auxquels sont confrontées actuellement les entreprises et la place centrale sur l’échiquier économique, c’est autour du jeu des pouvoirs dans l’entreprise, non seulement ceux des actionnaires, mais aussi ceux des dirigeants, qu’il convient de mener la réflexion.