bluuebunny/crossref_metadata_2025 huggingface dataset:
El páramo andino: características territoriales y estado ambiental. Aportes interdisciplinarios para su conocimiento
Authors: Serrano Giné David , Galárraga Sánchez Remigio
Published: August 2015

Se presentan las características generales del páramo andino, un ecosistema de gran interés social y territorial poco conocido entre los geógrafos españoles. La síntesis desarrollada constituye un estado de la cuestión actualizado y contrastado sobre los principales aspectos que definen y caracterizan este espacio. La perspectiva adoptada tiene un marcado carácter sistémico y focaliza en cuestiones de orden ambiental, por ser este aspecto el que mejor engloba la complejidad actual del páramo. Así, después de glosar el encuadre geográfico del páramo andino, se repasa de forma sumaria los aspectos que mejor describen el beneficio social de este ámbito, a saber los aprovechamientos hídricos, la ocupación del suelo y el uso que realizan las sociedades implicadas. El propósito principal de este artículo es dar a conocer a los geógrafos ibéricos un ámbito de trabajo de gran actualidad entre los geógrafos latinoamericanos.

[fr] Cet article expose les caractéristiques générales du páramo andin : un écosystème de grand intérêt social et territorial peu connu des géographes espagnols. Cet article constitue un état de l’art actualisée et comparé des principaux aspects qui définissent et caractérisent cet espace. La perspective adoptée a un caractère systémique, et focalise sur les questions environnementales, qui sont au centre des enjeux actuels du páramo. Ainsi, après un résumé du cadre géographique du páramo andin, on détaille les aspects qui décrivent le mieux les bénéfices de ce milieu, à savoir les exploitations hydrauliques, l’occupation du sol et l’usage qu’en ont les sociétés locales. L’objectif de ce travail est de faire connaître aux géographes ibériques un sujet de grande actualité entre géographes latino-américains.
A New Approach for Remote Sensing Image Sample Selection Based on Convex Theory
Authors: Xin Pan , Sun Hongbin
Published: August 2015

Advancements in remote sensing technology have led to improvements in the acquisition of land cover information. The extraction of accurate and timely knowledge about land cover from remote sensing imagery largely depends on the classification techniques used. Support vector machine has been receiving considerable attention as a promising method for classifying remote sensing imagery. However, the support vector machine learning process typically requires a large memory and significant computation time for treating a large sample set, in which some of the samples might be redundant and useless for the support vector machine model training. Therefore, higher-quality and fewer samples from the sample selection should be utilized for support vector machine-based remote sensing classification. A convex theory-based remote sensing sample selection algorithm for support vector machine classifiers is developed in this work. A Landsat-5 Thematic Mapper imagery acquired on August 31, 2009 (orbit number 113/27) is adopted in our experiments. The study area's land cover/use was divided into five categories. Using the region of interest tool, we select samples from the image of the study area, with each category consisting of 1000 independent pixels. Results show that for most cases, our method can achieve higher classification accuracy than random sample selection method.
The Smart Device Specification for Remote Labs
Authors: Salzmann Christophe , Govaerts Sten , Halimi Wissam , Gillet Denis
Published: August 2015

This paper presents the Smart Device specification to interface with remote labs. To encourage the broader sharing of remote labs, the Smart Device paradigm decouples the client from the server and provides well-defined interfaces between client and server. Such Smart Device services are exposed on the Internet and enable interoperability with client applications, other Smart Devices and external services (e.g. a booking service). This paper presents the extensible and platform-agnostic specification of the Smart Device services and internal functionalities. The Smart Device specification contains sufficient service metadata to enable the automatic generation of basic client applications. The specification is illustrated through an example and first implementations of the specification are presented.
Experimenting and Simulating Thermoelectric Cooling of an LED Module
Authors: Maaspuro Mika
Published: August 2015

Use of a thermoelectric component (TEC) for an LED module cooling will be studied. The issue will be approached by revealing the operation of a thermoelectric component known also as Peltier element, and the main equations describing its behaviour. An experimental setup including an LED module, a TEC, an heatsink and a fan will be build. Heat dissipation and the electrical performance measurements of the hole experimental setup will be conducted. The benefits and the limitations of TEC used in cooling, will be revealed. Cooling effect versus used electrical power will be studied. 3D thermal simulations for the experimental setup using a FEM simulation software will be presented. Alternatively, a standard circuit simulator will be used. A spice model, which imports TEC's parameters from the data sheet, will be developed. The spice simulation results are compared with the experimental results.
Development, Implementation, Assessment of a Web-based Circuit Solver for Teaching Basic Electrical Circuits Theory
Authors: Harb Shadi MS , Batarseh Issa , Harb Ahmad
Published: August 2015

In this paper, an interactive web-based circuit simulator tool (CirSim) is presented to enhance students learning skills and assist them to grasp the basic concepts of the preliminary electrical engineering courses by providing innovative methods for interactive teaching and testing. The project aims to achieve the following goals: 1) Develop enhanced problem solving skills using the internet as a portable platform for the education environment. 2) Develop design skills and sharpen critical thinking. 3) Develop global and comprehensive teaching circuit tools which can be adopted nationally for educational purposes. Students can use the online circuit simulator to carry out circuit simulation on the web and access it virtually from any place. The proposed simulator provides a user friendly graphical user interface (GUI) which has the capability to allow students to conduct DC and AC circuit simulation analysis and provide the option to plot the circuit responses graphically. Finally, a preliminary study has been done on a group of students to show the effectiveness of the e-learning using the proposed web-based circuit solver on the achievement of students. The results show a great feedback from students and improved performance in learning the basic electrical engineering concepts.
Microstructure and Physical Properties of Nanocrystalline Aluminum Consolidated by Spark Plasma Sintering
Authors: Liu Zhen Feng , Zhang Zhao Hui , Sun Yong Jun , Wang Fu Chi
Published: August 2015

Spark plasma sintering (SPS) technique was employed to fabricate nanocrystalline aluminum (Al) with the organic-coated Al nanopowders as raw material. A low initial pressure of 1 MPa and a high holding pressure of 300 MPa were used in the investigation. The effect of sintering temperature on the microstructure and the physical properties of the nanocrystalline Al was investigated. The results demonstrated that both the grain size and the thermal diffusivity of the nanocrystalline Al increase with an increase in sintering temperature. However, the resistivity of the nanocrystalline Al deceases with increasing sintering temperature.
Effect of Sintering Temperature on Microstructure and Mechanical Properties of Nanocrystalline Aluminum 5083 Alloy
Authors: Teng Ying Mei , Zhang Zhao Hui , Yuan Zi Zhou
Published: August 2015

The bulk nanocrystalline (NC) aluminum (Al) 5083 was synthesized by spark plasma sintering (SPS) technique with low initial pressure of 1 MPa, high holding pressure of 300 MPa and holding time of 4 min at different sintering temperatures, using surface passivated nanopowders. The effect of sintering temperature on microstructure and mechanical properties of the bulk NC Al 5083 were investigated. Results indicate that the density, grain size, the hardness and the compressive strength of the bulk NC Al 5083 increase with an increase in sintering temperature. The mechanical properties of the material are greatly improved due to the fine grain size. The bulk NC Al 5083 sintered at 723 K has the highest micro-hardness of 2.37 GPa and the best compressive strength of 845 MPa.
Structural Response under Blast Loads - Simplified Numerical Analysis
Authors: Hao Hong , Li Jun
Published: August 2015

Efficiently and accurately predicting structural dynamic response and damage to external blast loading is a big challenge to both structural engineers and researchers. Theoretical investigation on this problem is complex as it involves non-linear inelastic material properties, effect of time varying strain rates, uncertainties of blast load calculations and the time-dependent structural deformations. Experimental investigation can provide valuable data for locating the damage and establishing the damage criteria. The damage curves generated from the extensive experimental study can provide quick assessment of the structural status. However, such blast experiments always involve safety concern and can be beyond the affordability. Besides this, the correlation of the experimental data with predictive method is difficult since it requires a large number of tests to generate damage curves. Compared with the theoretical and experimental study, numerical simulation does not involve any safety concern and is cost-effective. With verified material model and element model, numerical simulation could be powerful supplement to the experimental tests. However, numerical simulation of structural responses under blast and impact loading could be time and resource consuming. Even with modern computer technology and computational mechanics method, detailed modelling and numerical simulation of responses of structures subjected to blast loadings are still often prohibitive. To address this issue, in the present study, an efficient numerical method is proposed to reliably calculate structural response and damage to blast loadings.
Study on the Evolution of Adiabatic Shear Band of a High Strength Steel
Authors: Du Wen Wen , Wang Qian , Zhao Deng Hui , Wang Lin
Published: August 2015

The evolution process of a high strength steel which subjected with three different heat treatment proceedings and gets different quasi-static tensile properties was investigated in this paper. To precisely control the plastic deformation of the cylinder and capture the development process of adiabatic shear bands, stopper ring was used in Split Hopkinson Pressure Bar (SHPB). Combining the stress-strain curves and microstructures after SHPB tests, the microstructure evolution from the nucleation of adiabatic shear bands to fracture of the cylindrical steel were observed. The experimental results have demonstrated that there are similar fracture procedures of the steel treated through different heat treatments. Shear bands form firstly, then micro-cracks develop from shear bands, and lead to macro-crack finally. However, the critical strains for nucleation of ASBs and the time spending on the fracture procedure of the steel treated at different heat treatments are different. Samples treated at 900°C/AC exhibit the best resistance to adiabatic shear sensitivity when compressed under high strain rates.
Three-Sheet Spot Welds of 5052 Aluminum Alloy: Weld Growth and Failure Behavior
Authors: Yan Fu Yu , Luo Zhen , Chao Yuh J. , Ao San San , Li Yang , Cui Xue Tuan
Published: August 2015

Resistance spot welding is used extensively in auto industry. Every commercial vehicle has 4000-5000 spot welds. The weld ability, performance, and reliability are therefore important issues in design. In this paper, we studied weld nugget formation and failure behavior of three-sheet 5052 aluminum alloy resistance spot welds. The Peltier effect between the Cu-Al (the electrode and the Al worksheet) to the nugget formation was noticed. The mechanical strength and fracture mode of the weld nuggets at the upper and lower interfaces were studied using tensile shear specimen configuration. Three failure modes were identified, namely, interfacial, mixed, and pull-out. The critical welding time and critical nugget diameter corresponding to the transitions of these modes were investigated. Finally, an empirical failure load formula for three-sheet weld similar to two-sheet spot weld was developed.
Research of the Anti-Penetration Mechanism for Titanium Alloys Armor Based on 3D Optical Scanning Technology
Authors: Xia Yu Meng , Fan Qun Bo , Gao Rui Hua , Li Guo Ju , Huo Li Rui , Zhang Yi Peng
Published: August 2015

To reveal the anti-penetration mechanism of titanium alloys armor quantitively, the volumes of the front crater region, the ductile hole-enlargement region, as well as the back caving region of Ti-6Al-4V alloy and β20C alloy were measured via 3D Optical scanning technology. The experimental results show that β20C alloy, of which the volume fraction of ductile hole-enlargement region is 51%, 10% larger than that of Ti-6Al-4V alloy, presents a better ballistic performance. It is found that the ballistic performance is closely related to the volume of ductile hole-enlargement region and a relatively larger ductile hole is beneficial to improve the ballistic performance. However, the ballistic performance shows no improvement with increasing the volume of front crater region.
Critical Dimensions of Tensile-Shear Specimen for Resistance Spot Welds
Authors: Cui Xue Tuan , Chao Yuh J. , Luo Zhen , Ao San San , Yan Fu Yu
Published: August 2015

Resistance spot welding is used extensively in auto industry. Every commercial vehicle has 4000-5000 spot welds. The weld ability, performance, and reliability are therefore important issues in design. Tensile-shear tests are normally performed to evaluate the weld quality and acquire the mechanical strength of spot welds. However, different industry test standards often specify different dimensions for the tensile-shear specimen. In this work, we investigate the failure load and energy absorption of the spot welds made of Q235 steel using tensile-shear specimens of different dimensions. The objective is (a) to determine a specimen dimension independent geometry for failure strength, and (2) to call attention to the deficiency of some of the test standards.
The Experiment Study on Flash Spectrum Produced by Hypervelocity Impact
Authors: Zhang Kai , Zhang Qing Ming , Long Ren Rong
Published: August 2015

It is an inevitable phenomenon that flash is generated in the process of hypervelocity impact. The research on impact flash is of important significance for assessing the collision between space debris and spacecraft, identifying the material properties on the surface of planet, evaluating the damage of weapon system. A measurement system was built in order to acquire flash spectrum ranging in wavelength from 200 to 1100nm. The relationship between flash intensity and impact velocity was studied. The spectrum consists of line spectrum and continuous spectrum. Line spectrum mainly concentrates in the range of 200-500nm. The spectral lines of the elements were identified. The strong flash happens within 2.2ms after beginning to impact. In addition, the electron temperature of plasma produced in hypervelocity impact is calculated by spectral method, and compared with the temperature measured by Langmuir three probes.
The Dynamic Behavior of High Speed Train Using Magnetorheological Technology on the Curve Track
Authors: Deng Hua Xia , Zhou Lai Jun , Zhao Shi Yu , Li Wei Hua , Sun Shuai Shuai , Zhang Jin , Yu Lian Dong
Published: August 2015

The era of high speed railway has come and the most important issue of the high speed train is the safety, which is directly related to billions of families. One of the most serious threats to the safety of the high speed train is the vibration of train body at curve track, which may cause the train off the track. Semi-active vibration control method is a possible solution compared with active control method which has robust problem and passive control method which has efficiency issue. Magnetorheological technology is a typical semi-active vibration control method which has been widely used in the automobile, architectural construction and aerospace. The high speed train using magnetorheological technology has not been fully investigated especially for the dynamic performance at curve track. In this paper, a high-speed train model with MRF dampers is simulated by a combined ADAMS and MATLAB simulation. The dynamic performance of high speed train operating at different speeds and turning radius is investigated to reveal the mechanism of how the MRF damper affects the train’s stability and vibration. The results show that the semi-active suspension installed with MRF dampers substantially improves the stability and dynamic performance of the train at curve track.
Experimental Study and Numerical Simulation of the Tensile Test for GH4169 Coated with YSZ Coating at High Temperature
Authors: Wang Lin Lin , Fan Qun Bo , Zhang Hong Mei , Wang Fu Chi
Published: August 2015

In this study, high temperature tensile test was conducted on the specimen of superalloy GH4169 coated with wt8%-YSZ under the conditions of 950°C and 80MPa. By using finite element (FE) simulation method, the failure initiation and evolution of the metal substrate and YSZ coating were predicted. It was found that stress concentration originally occurred in the YSZ ceramic top coating, causing an axial stress and triggering severe debonding failure in the center region of the specimen at t=180s. With increased load, further interfacial debonding failure of the residual coating occurred due to the presence of oblique tensile stress and at t=900s, and only a few residues can be seen at the arc transitional region. Subsequently, the metal substrate was subjected to uniform tensile deformation and finally ruptured at t=76min with apparent necking. In addition, it was notable that YSZ coating can relieve stress significantly (nearly 40% lower), thus helping prolong the substrate's service life in the same environment. Simulated results were consistent with observed behavior.
Analyzing Stress Wave Propagation in a Hollow Bar Loaded Three-Point Bend Fracture Test Using Numerical Methods
Authors: Javed Raja Ahsan , Zhu Shi Fan , Guo Chun Huan , Jiang Feng Chun
Published: August 2015

Modified Hopkinson pressure bar apparatus is widely used to investigate the dynamic fracture behavior of materials at higher rate loading. While using a small sample for fracture toughness testing, plane strain conditions are compromised. In the current work, a large diameter two-bar/ three-point bend fracture setup is used to analyze stress wave propagation behavior within a larger cracked specimen. The experimental setup model consists of striker, incident bar, loading pin, cracked three-point specimen, span and transmission bar. The model is prepared using ANSYS software and the transient dynamic analysis technique is used to simulate the dynamic load. The effects of increased transient time on the stress wave propagation behavior within the cracked sample and the stress and strain values at the crack tip of the three-point bend specimen are analyzed. In addition, the effects of the hollow striker, the hollow incident bar and the specimen span are studied. It is found that during large specimen testing, an increase in the transient time results in the lower stress and strain values in the specimen crack-tip. The relationship of the specimen span, the striker and the incident bars with the strain values in the specimen is analyzed and a method for the three-point bend specimen testing at the higher strain rates is also proposed.
Modified Quartet Structure Generation Set Reconstruction of Finite Element Model for Co-Continuous Ceramic Composites
Authors: Wang Qing Xiang , Zhang Hong Mei , Cai Hong Nian , Fan Qun Bo
Published: August 2015

Co-continuous ceramic composites have a complicated topology structure which makes it much more difficult for finite element model reconstruction. In this paper, the two-dimensional co-continuous ceramic composites finite element model is reconstructed by a modified quartet structure generation set method which modified the generation parameters based on quartet structure generation set (QSGS) method, and a numerical simulation at high strain rate is accomplished. The content mainly contains: (1) The distribution features of metal phase and ceramic phase of real co-continuous ceramic composites SEM image is calculated by mathematical statistics to determine the parameters that control the reconstruction such as volume fraction, core distribution probability and directional growth probability; (2) Two phase volume fraction and 2-point correlation function of the reconstructed finite element model is calculated as the quality assessment parameters, which verify the reconstructed finite element model are in allowable error range compared with the real SEM image; (3) Numerical simulation at high strain rate is carried out using the reconstructed finite element model. The failure behavior of co-continuous ceramic composites at high strain rate is analyzed, validates the reconstructed finite element model meets the requirements of numerical calculation.
Application of the Continuous Rotating Detonation to Gas Turbine
Authors: Wolański Piotr
Published: August 2015

In this paper experimental research on rotating detonation carried out at the Institute of Aviation (IA) in Warsaw are presented. Research was focused on 3-D numerical simulations of detonation propagation in cylindrical chambers and on evaluation of conditions at which rotating detonation is propagating in cylindrical channels for kerosene-hydrogen-air mixtures. Conducted simulations are used for analysis of complex flow – detonation front interaction and for estimating the thermodynamic parameters of the outflow gases. Extensive research on continuously propagating rotating detonation in many different chambers and in different fuel-air mixtures were tested. On bases of conducted calculations, as well as results of experimental study, a few chamber were selected for tests with GTD-350 engine. It was shown that application of the continuously rotating detonation to GTD-350 engine can results with increased efficiency of the engine.
The Button Head Bullet Effects on the Incident Pulse of Split Hopkinson Press Bar
Authors: Qu Jia , Chen Geng , Zou Guang Ping
Published: August 2015

In order to make the specimen deformed under a constant strain rate and the stress in the specimen kept homogeneous, the wave shaper technology was adopted to modify the incidence waves of the normal Split Hopkinson Press Bar. A method of changing the shape of the bullet was suggested to be applied on the SHPB. Bullets with different length and different curvature have been researched in this paper. And the effection of the button head bullet about incidence pulse was simulated with Lagrange method by ANSYS/LS-DYNA. It is shown in the results that changing the curvature of the bullet impact the rising edge of incidence waves, and the peak stress increase with the speed of the bullet increase, the peak stress and length of incidence waves increased with the length of the button head bullet, when the peak stress reached a certain strength, increasing the bullet length could make the stress peak value lasted longer. Due to the reason that the button head bullet was based on the elastic wave theory, the wave length and the max stress of the shaped wave would be controlled conveniently and avoid the shortcoming that the analogue specimens could not be recycled in the normal pulse shaper technology.
Simultaneous Measurement of In-Plane and Out-of-Plane Deformations Using Dual-Beam Spatial-Carrier Digital Speckle Pattern Interferometry
Authors: Liu Kai , Wu Si Jin , Gao Xin Ya , Yang Lian Xiang
Published: August 2015

Digital speckle pattern interferometry (DSPI) is an advanced technique for both in-plane and out-of-plane deformation measurements of diffuse surfaces in nanoscale. It has been widely used in aerospace engineering and other high-tech industries due to the advantages of non-contact, high-accuracy and full-field measurement. Traditionally, DSPI uses temporal phase shifting method to achieve precise deformation measurement, but it is only suitable for quasi-static deformation. Spatial-carrier method is another effective phase retrieval method used in DSPI and its validity has been verified in some DSPI setups. DSPI with spatial-carrier method enjoys the advantages of simple optical arrangement, easy operation, and above all, high-speed measurement of deformation. This paper introduces a dual-beam spatial-carrier digital speckle pattern interferometry system, with which in-plane and out-of-plane deformations can be measured simultaneously as well as quickly. In the optical setup, two lasers are employed to illuminate the measured object with different illumination angles, and two single-mode fibers server as carriers to transmit the reference beams. In-plane and out-of-plane deformations can be obtained by combining the phase maps of both channels. Theoretical discussion and experimental analysis are both presented.
ViBe with Adaptive Threshold Based on Energy Minimization
Authors: Xie Liang , Zhang Xiao Hu , Guo Peng Yu , Long Gu Can
Published: August 2015

VIsual Background Extractor (VIBe) is a simple and effective background subtraction model, it is important to choose the threshold according to different environments. A new method based on the VIBe is presented which uses the adaptive threshold. We give a new description of the similarity degree without threshold, and then use the energy minimization model to combine the spatial information and show that dynamically choosing threshold in our kernel estimates at each individual pixel can significantly improve results. To compare with the traditional VIBe algorithms, a synthetic test SABS and a real world test I2R are used. Experiment shows that the presented method is on average 10% better than the traditional VIBe in accuracy.
Some Possibilities of Hypercumulative Regime of Jet Formations
Authors: Minin Vladilen , Minin Oleg , Minin Igor
Published: August 2015

Basic physical problems of jet formation process on the basis of Lavrentiev-Birkhoff classical scheme are analyzed. It is shown that in process of realization of hypercumulation conditions for jet formation without complete stagnation point involving formation of the inner zone of constant pressure (dead zone), the flow mass is always greater than slug mass, that is unachievable in the known models. Smoothing effect of this zone on the development of different types disturbances, particularly, smoothing Rayleigh-Taylor instability for thin liner may be expected and shown in simulations.
Dynamic Deformation Response of G33 Steel under High Temperature
Authors: Zhang You Jing , Cai Hong Nian , Cheng Xing Wang , Zhao Shuang Zan
Published: August 2015

The high temperature deformation and fracture behavior of ultra-high strength G33 steel under high strain rate compression are investigated by means of a split Hopkinson p
ressure bar. Impact tests are performed at strain rates of 1000/s and 2200/s and at temperatures ranging from 25°C to 700°C. The SEM and TEM techniques are also used to analyze the microstructure evolution of the adiabatic shear band (ASB) and fracture characteristics of the deformed specimens at high temperature. The experimental results indicate that the flow stress of G33 steel is significantly dependent on temperatures and strain rates. The flow stress of G33 steel increases with the increase of strain rates, but decreases with the increase of temperatures. The strain rate sensitivity is more pronounced at the low temperature of 25°C. In addition, G33 steel is more liable to fracture at high temperatures than at 25°C. Observations of microstructure show two well-developed symmetric parabolic adiabatic shear bands on the longitudinal cross-section of the cylindrical specimen deformed at the temperature of 700°C and at the strain rate of 2200/s. Within the ASB, the width of the fine equiaxed grain structure is about 7μm. The size of those equiaxed grains is approximately 100nm. The fracture analysis results indicate that the ASBs are the predominant deformation and the specimens fracture along adiabatic shear bands. The fracture surfaces of the deformed G33 steel specimens are characterized by two alternating zones: rough dimple zone and relatively smooth shear zone. Further observations reveal that smooth shear zones consist of severely sheared dimples.
The Correlation between Microstructure and Dynamic Mechanical Property of Heat Treated Β20C Titanium Alloy Based on Different Forging Processes
Authors: Huo Li Rui , Fan Qun Bo , Gao Rui Hua , Wang Fu Chi
Published: August 2015

As a new material, the microstructure of β20C titanium alloy can match well with property by forging process. However, the microstructure of billet is inhomogeneous in actual forging. For ensuring microstructures homogenization, two forging processes are designed. Process 1 is large deformation above the phase transition (T=1050°C, 70% deformation) and small deformation in two-phase region (T=860°C~890°C, ≤40% deformation). Process 2 is small deformation above the phase transition (T=1050°C, 40% deformation) and large deformation in two-phase region (T=860°C~890°C, 50%~60% deformation). Then microstructures are observed and dynamic compressive strength and the critical fracture strain of samples are test after solid-solution treatment. It turns out that the homogeneity of microstructure of process 2 is improved by heat treatment. The microstructure is lamellar microstructure with 1650MPa dynamic strength and 15% critical fracture strain through “Process 1 + 840°C 1h/FC” while the microstructure is equiaxed microstructure with 1650MPa dynamic strength and 20% critical fracture strain through “Process 2 + 840°C 1h/FC”. In conclusion, the microstructure of large deformation in two-phase region can accumulate more deformation energy which is beneficial for dynamic recrystallization.
Sintering Mechanism of Ti-6Al-4V Prepared by SPS
Authors: Lu Ji Fang , Zhang Zhao Hui , Liu Zhen Feng , Wang Fu Chi
Published: August 2015

Ti-6Al-4V compact bulk was fabricated by Spark plasma sintering (SPS) with initial pressure of 1.7 MPa, holding pressure of 50 MPa, heating rate of 100 °C/min, and holding time of 5 min at different sintering temperature. The fracture morphology of the specimen sintered at different temperatures was observed to investigate the sintering mechanism. It can be concluded that there are four stages in the SPS process: activation and rearrangement of particles, connection of particles, growth of sintering neck and bulk deformation. The high-quality bulk compact can be obtained when the above mentioned four sintering stages proceed in turn and are all fully completed. The compact bulk has the best mechanical properties when the sintering temperature was 1050°C. The relative density of the bulk Ti-6Al-4V exceeds 99.5%. The tensile strength and the elongation of Ti-6Al-4V obtained by SPS process are 901 MPa and 13.9%, respectively.
Ubiquitination as a Mechanism To Transport Soluble Mycobacterial and Eukaryotic Proteins to Exosomes
Authors: Smith Victoria L. , Jackson Liam , Schorey Jeffrey S.
Published: August 2015

Exosomes are extracellular vesicles of endocytic origin that function in intercellular communication. Our previous studies indicate that exosomes released from Mycobacterium tuberculosis-infected macrophages contain soluble mycobacterial proteins. However, it was unclear how these secreted proteins were targeted to exosomes. In this study, we determined that exosome production by the murine macrophage cell line RAW264.7 requires the endosomal sorting complexes required for transport and that trafficking of mycobacterial proteins from phagocytosed bacilli to exosomes was dependent on protein ubiquitination. Moreover, soluble mycobacterial proteins, when added exogenously to RAW264.7 or human HEK293 cells, were endocytosed, ubiquitinated, and released via exosomes. This suggested that endocytosed proteins could be recycled from cells through exosomes. This hypothesis was supported using the tumor-associated protein He4, which, when endocytosed by RAW264.7 or HEK293 cells, was transported to exosomes in a ubiquitin-dependent manner. Our data suggest that ubiquitination is a modification sufficient for trafficking soluble proteins within the phagocytic/endocytic network to exosomes.
Hepatic Stellate Cells Inhibit T Cells through Active TGF-β1 from a Cell Surface–Bound Latent TGF-β1/GARP Complex
Authors: Li Yan , Kim Byung-Gyu , Qian Shiguang , Letterio John J. , Fung John J. , Lu Lina , Lin Feng
Published: August 2015

Hepatic stellate cells (HSCs) inhibit T cells, a process that could help the liver to maintain its immunoprivileged status. HSCs secrete latent TGF-β1, but the detailed mechanisms by which latent TGF-β1 is activated and whether it plays any role in HSC-mediated T cell suppression remain unclear. Glycoprotein A repetitions predominant (GARP) is a surface marker of activated regulatory T cells. GARP binds latent TGF-β1 for its activation, which is critical for regulatory T cells to suppress effector T cells; however, it is still unclear whether GARP is present on HSCs and whether it has any impact on HSC function. In this study, we found that TGF-β1+/− HSCs, which produce reduced levels of TGF-β1, showed decreased potency in inhibiting T cells. We also found that pharmaceutical or genetic inhibition of the TGF-β1 signaling pathway reduced the T cell–inhibiting activity of HSCs. Additionally, using isolated primary HSCs, we demonstrated that GARP was constitutively expressed on HSCs. Blocking GARP function or knocking down GARP expression significantly impaired the potency of HSCs to suppress the proliferation of and IFN-γ production from activated T cells, suggesting that GARP is important for HSCs to inhibit T cells. These results demonstrate the unexpected presence of GARP on HSCs and its significance in regard to the ability of HSCs to activate latent TGF-β1 and thereby inhibit T cells. Our study reveals a new mechanism for HSC-mediated immune regulation and potentially for other conditions, such as liver fibrosis, that involve HSC-secreted TGF-β1.
Defective NK Cells in Acute Myeloid Leukemia Patients at Diagnosis Are Associated with Blast Transcriptional Signatures of Immune Evasion
Authors: Khaznadar Zena , Boissel Nicolas , Agaugué Sophie , Henry Guylaine , Cheok Meyling , Vignon Marguerite , Geromin Daniela , Cayuela Jean-Michel , Castaigne Sylvie , Pautas Cécile , Raffoux Emmanuel , Lachuer Joel , Sigaux François , Preudhomme Claude , Dombret Hervé , Dulphy Nicolas , Toubert Antoine
Published: August 2015

Acute myeloid leukemia (AML) is a heterogeneous group of malignancies that may be sensitive to the NK cell antitumor response. However, NK cells are frequently defective in AML. In this study, we found in an exploratory cohort (n = 46) that NK cell status at diagnosis of AML separated patients in two groups with a different clinical outcome. Patients with a deficient NK cell profile, including reduced expression of some activating NK receptors (e.g., DNAX accessory molecule-1, NKp46, and NKG2D) and decreased IFN-γ production, had a significantly higher risk of relapse (p = 0.03) independently of cytogenetic classification in multivariate analysis. Patients with defective NK cells showed a profound gene expression decrease in AML blasts for cytokine and chemokine signaling (e.g., IL15, IFNGR1, IFNGR2, and CXCR4), Ag processing (e.g., HLA-DRA, HLA-DRB1, and CD74) and adhesion molecule pathways (e.g., PVR and ICAM1). A set of 388 leukemic classifier genes defined in the exploratory cohort was independently validated in a multicentric cohort of 194 AML patients. In total, these data evidenced the interplay between NK cells and AML blasts at diagnosis allowing an immune-based stratification of AML patients independently of clinical classifications.
A Detailed Characterization of the Dysfunctional Immunity and Abnormal Myelopoiesis Induced by Severe Shock and Trauma in the Aged
Authors: Nacionales Dina C. , Szpila Benjamin , Ungaro Ricardo , Lopez M. Cecilia , Zhang Jianyi , Gentile Lori F. , Cuenca Angela L. , Vanzant Erin , Mathias Brittany , Jyot Jeevan , Westerveld Donevan , Bihorac Azra , Joseph Anna , Mohr Alicia , Duckworth Lizette V. , Moore Frederick A. , Baker Henry V. , Leeuwenburgh Christiaan , Moldawer Lyle L. , Brakenridge Scott , Efron Philip A.
Published: August 2015

The elderly are particularly susceptible to trauma, and their outcomes are frequently dismal. Such patients often have complicated clinical courses and ultimately die of infection and sepsis. Recent research has revealed that although elderly subjects have increased baseline inflammation as compared with their younger counterparts, the elderly do not respond to severe infection or injury with an exaggerated inflammatory response. Initial retrospective analysis of clinical data from the Glue Grant trauma database demonstrated that despite a similar frequency, elderly trauma patients have worse outcomes to pneumonia than younger subjects do. Subsequent analysis with a murine trauma model also demonstrated that elderly mice had increased mortality after posttrauma Pseudomonas pneumonia. Blood, bone marrow, and bronchoalveolar lavage sample analyses from juvenile and 20–24-mo-old mice showed that increased mortality to trauma combined with secondary infection in the aged are not due to an exaggerated inflammatory response. Rather, they are due to a failure of bone marrow progenitors, blood neutrophils, and bronchoalveolar lavage cells to initiate and complete an emergency myelopoietic response, engendering myeloid cells that fail to clear secondary infection. In addition, elderly people appeared unable to resolve their inflammatory response to severe injury effectively.
Upper Paleozoic stratigraphy of the Eagle Plain Basin, Yukon Territory
Authors: Martin H L
Published: August 2015

Upper Paleozoic strata in the southern part of the Eagle Plain Basin are termed the Imperial Formation of Late Devonian age, the unnamed shale unit of Devonian and Mississippian age, and the Hart River Formation of Late Mississippian (Chesteran) age. The latter
is formally subdivided into the Birch, Canoe River, and Chance Sandstone Members. Both the Birch and Chance Sandstone Members are reservoir rocks where oil and gas have been discovered in commercial quantities. The hydrocarbons are present in nonargillaceous, conglomeratic sandstone whereas the
intervening Canoe River Member is a siliceous shale in the southeast grading to a siliceous limestone in the central and western parts of the basin. The strata are believed to have been deposited in a deep water trough subparallel to the present-day Richardson Mountains which form the eastern border
of the basin; turbidite flows are considered to be responsible for the formation of the conglomeratic sandstone.
Relationship of structural lineaments and mineral occurrences in the Abitibi area of the Canadian Shield
Authors: Kutina J , Fabbri A G
Published: August 2015

The Abitibi and of the Canadian Shield, located between 76° and 84 ° W and 47 ° 30' and 49 N in Ontario and between 48° and 49° N in Quebec, was studied in context with the structural geology of a considerable part of the Canadian Shield.

Comparison of lineaments in very distant are as of the Canadian Shield suggests that the Shield structure is strongly influence d by one prominent pattern of deep-seated fractures. A spacing of 100 miles between the cast west lineaments of the Canadian Arctic is recognizable also in the drainage pat
tern east of James Bay and is reflected in the Abitibi area. It is compatible with a set of east-west trending major fractures by J. Kalliokoski as bounding crustal blocks with cores of granitic rocks. The two schemes have been derived in different ways and fully independently of each other.

The spacing between the Hudson Bay Paleolineame nt - a significant geofracture of the Canadian Shield - and the Mattagami River Lineament was used as the unit interval in the north-south set of fracture -trajectories of the prospecting net for the Superior Provinces south of Hudson Bay. The
corresponding unit interval in the eastern part of this area is smaller. Fifteen comparable intersections have been postulate d. Endogenous ore deposits are known to occur a long seven of them and the remaining eight are recommended for prospecting.

In the Abitibi area intersecting fractures of these sets are present and the distribution of gold and copper deposits coincides with them. The ore deposits are clustered at or near the intersect ions of major fractures (Noranda, Kirk land Lake , Matachewan and Timmins-Porcupine deposit clusters).
Several recommendations for prospecting can be deduced from the relationship of the fracture pattern and the distribution of about 1,300 gold and about 700 copper occurrences of the area. Sorne recommendations are presented in this paper.

With respect to the individual ore districts, the relationship of ore deposits to volcanic centres, as outlined in 1967 by Wilson is emphasized. The large-scale deep-seated fractures may control the general distribution of volcanic centres and the associated ore deposition and this possibility
should be tested.
Surficial geology of the Drumheller area, Alberta
Authors: Stalker A M
Published: August 2015

The Drumheller area of central Alberta covers about 6,000 square miles directly northeast of Calgary. Although the Rocky Mountain Foothills are nearby, only the most westerly parts of the area were affected by Cordilleran glaciers. Laurentide glaciers, on the
other hand, strongly glaciated the whole area several times during the Quaternary Period. Information on early glaciations is scanty as most of the area lies near the drainage divide between Red Deer and Bow Rivers-a region ill-suited for preserving early glacier deposits from destruction by
subsequent glaciers. Thick sequences of drift have survived in the preglacial Bow Valley, which crosses the southwestern and southeastern parts of the area, but they are poorly exposed. In the southeast, drift overlies enormous deposits of preglacial (Pliocene and Pleistocene) gravel and sand.

The retreat and the deposits of the Classical Wisconsin glacier are described in detail. The chief feature during the over-all retreat was the lnnisfail rejuvenation, which corresponds to one of the Wisconsin stades. During this rejuvenation, the ice thickened at least 500 feet and advanced as much
as 125 miles. Most of the spillways in the region developed either during the glacial retreat that immediately preceded this readvance, or during the recession of the still earlier, pre-Classical Wisconsin glacier. They were reoccupied by meltwater streams following the Innisfail Readvance.

Over much of the west half of the area the glacier retreated uphill, retained movement until it had become thin, and was effectively drained. Elsewhere it retreated downhill, stagnated while still fairly thick, and, for the most part, was saturated with water. The result in the western districts was
the abundance of esker ridges, ice-flow markings, and spillways, along with extensive areas of till plain and outwash, that form a vivid contrast to the expanses of hummocky moraine and lake plain found in the central and eastern districts.

The term 'murdlin' is introduced to designate an elongate ice-flow feature, previously undescribed. A 'murdlin' resembles a drumlin both in size and relation to ice movement, but it differs markedly in shape and genesis.
Geology of the late Precambrian Fury and Hecla Group, northwest Baffin Island, District of Franklin
Authors: Chandler F W
Published: August 2015

The gently inclined, unmetamorphosed, miogeoclinal, Fury and Hecla Group consists of 6000 m of quartz arenite and minor shale and dolomite. Mafic volcanics and intrusives give Neohelikian to Hadrynian K-Ar whole-rock ages. The group is correlated with the lower
part of the Bylot Supergroup, 200 km north. As with the Bylot, mainly shallow marine deposition is indicated, with ocean to the west or northwest. The alluvial, basal, 500 m thick, Nyeboe Formation consists mainly of red quartz arenite. Marine dolomite pinches out eastward. The Sikosak Formation, at
least 150 m of white quartz arenite, contains 0-30 m of basalt flows of the Hansen Formation, which, descending westward in the Sikisak, suggest that the tidal marine unit migrated west. The Agu Bay Format ion contains a 0-10 m basal stromatolitic shallow-water dolomite member, a 75 m marine shelf
black shale member, both absent in the east, and a 500 m thick upward-coarsening and shoaling redbed member. Pinkish white quartzite of the shallow marine Whyte Inlet Formation thins west from 3 km to bare mappability. The Autridge Formation, with a lower Mikkelsen Member, 1500 m of drab quartz
arenite and black shale, and an upper Cape Appel Member, 500 m of black shale, may be an outer shelf equivalent of the Whyte Inlet.

Uranium occurs in the subjacent granitic basement and in a quartz stockwork occupying a fault in the Nyeboe Formation.
Report on the monitoring of micro-earthquakes during the hydraulic fracturing conducted in New Brunswick in August and September 2014
Authors: Lamontagne M , Lavoie D
Published: August 2015

This report examines whether the hydraulic fracturing of August and September 2014 in the McCully gas field and adjacent area produced any induced events that could be detected by the six-station seismograph array of southeastern New Brunswick. After verifying
the automatic triggers of each individual station and visually scanning the nearest station to the wells where hydraulic fracturing occurred, it was found that no induced micro-earthquake occurred within the few hours during and following hydraulic fracturing operations.
Uncovering Web search tactics in South African higher education
Authors: Civilcharran Surika , Hughes Mitchell , Maharaj Manoj S.
Published: August 2015

Background: The potential of the World Wide Web (‘the Web’) as a tool for information retrieval in higher education is beyond question. Harnessing this potential, however, remains a challenge, particularly in the context of developing countries, where students are drawn from diverse socio-economic, educational and technological backgrounds. Objectives: The purpose of this study is to identify the Web search tactics used by postgraduate students in order to address the weaknesses of undergraduate students with regard to their Web searching tactics. This article forms part of a wider study into postgraduate students’ information retrieval strategies at the University of KwaZulu-Natal, Pietermaritzburg campus, South Africa. Method: The study utilised the mixed methods approach, employing both questionnaires (Phase 1) and structured interviews (Phase 2), and was largely underpinned by Bates’s model of information search tactics. This article reports and reflects on the findings of Phase 1, which focused on identifying the Web search tactics employed by postgraduate students. Results: Findings indicated a preference for lower-level Web search tactics, despite respondents largely self-reporting as intermediate or expert users. Moreover, the majority of respondents gained their knowledge on Web searching through experience and only a quarter of respondents have been given formal training on Web searching. Conclusion: In addition to contributing to theory, it is envisaged that this article will contribute to practice by informing the design of undergraduate training interventions to proactively address the information retrieval challenges faced by novice users. Subsequent papers will report on Phase 2 of the study.