bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical Modelling of Sayano-Shushenskaya Dam Displacement Process after 2009 Accident
Authors: Khoroshilov V.S.
Published: November 2018

The research presented in the article is of cutting-edge importance because it proves the necessity to develop prognostic mathematical models with the view to studying the behavior of high-head dams for identifying the regularities of their deformations development process and thus providing quantitative definition for the set criteria values of the diagnostic indices to ensure safe operation of such structures. The paper focuses on the peculiarities of building prognostic mathematical models of the dynamic type on the basis of recurrent equations of the 1stand 2ndorders of different types depending on the order of the mathematical model, number of the principal acting factors and discreteness of the input data, with decorrelation of the input actions and sequence of transport delay introduction. It is shown that the properties of the recurrent equation solution in the form of two first conditional moment generating functions of the displacement process of the observed points in the structure delineate a prognostic model which allows predicting the displacements of the observed points. The paper describes the sequence of estimation stages during the creation of prognostic mathematical models in respect to the character of the predictive problem for various time periods of the structure operation. Different combinations of input actions and discreteness of input data, as well as their decorrelation, have been used. We also applied transport delay in order to correctly consider the inertial delay of the dam under different loads. To account for the residual part of the inertial delay, which is affected by random and unaccounted for factors, we used the autoregression model of the process development regularity. To determine the order of the autoregression model, we calculated asymptotically unbiased ratings of the correlation function for the residual error as a difference between the actual and predicted displacements. Methodological specifics of constructing prognostic models have been established in the context of the factors above. Prognostic mathematical models of different types have been developed for the selected period of the dam operation and the results of prediction have been discussed.
Corrosion Rate Estimation in Steel Sheet Pile Walls - Comparison between Empirical Models and Eurocode 3, Part 5
Authors: Balegh Benamar , Trouzine Habib
Published: November 2018

Steel sheet pile wall corrosion in soils and water is a complex phenomenon. The deterioration of these structures is costly and difficult to predict. The aim of this paper was to deal some empirical corrosion models which are analyzed and compared to Eurocode 3, Part 5 to estimate corrosion rate and the loss of thickness of anchored steel sheet pile wall. The results show that care should be taken to ensure that the maximum bending moments do not occur at the same level as the main corrosion zones. Furthermore, it is possible to define an upper and a lower bound, corresponding respectively to the presence of sea water in low water and the undisturbed natural soils, in order to predict the loss of thickness due to corrosion.
Effect of Thermal Dependency of Diameter on Density of States for Zigzag Carbon Nano-Tubes
Authors: Ahmadabadi Hajar Nili , Ghafouri-Khosrowshahi Abolfazl , Ahmadimoghaddam Davoud , Nili-Ahmadabadi Amir
Published: November 2018

Gaining control over the various parameters of carbon nanotubes-(CNTs) has always been a challenge for researchers. This is because, each parameter depends on a carbon nanotube's dimensions in addition to its structure and composition. This paper aims to investigate how the thermal dependency of structural parameters -like diameter- affects the density of states (DOS). To accomplish this, the study first reviews the basic theoretical aspects of CNTs, we then present calculations of the energy band structures for armchair carbon nanotubes-(aCNTs), zigzag carbon nanotubes-(zCNTs), and chiral carbon nanotubes-(cCNTs). Finally, the study derives the DOSs to help provide an understanding of the relationship between the radial expansion of the diameter and the DOS for typical zCNTs.
Structure, Microstructure and Magnetic Properties of Nanostructured Alloys Fe-Nd-B Prepared by Mechanical Alloying
Authors: Boughedaoui Rachid , Azzaz Mohamed Cherif , Melouah Mohamed Tahar , El Mohri Abdennour , Zergoug M. , Lounis Azzeddine , Azzaz Mohamed
Published: November 2018

Nanocrystalline Fe76Nd16B8Des échantillons d'alliage (% atomique) ont été préparés à partir de poudres élémentaires pures par fraisage mécanique à haute énergie. Les matériaux obtenus ont été caractérisés par plusieurs techniques, telles que la diffraction des rayons X (DRX), qui ont permis la dissolution du néodyme dans la phase de fer en fonction du temps de broyage; les résultats obtenus indiquent que la solution solide a été obtenue. Après 20 heures de broyage à une vitesse de 400 tr / min. La méthode d'analyse Williamson-Hall a été utilisée pour exploiter les modèles DRX enregistrés. La taille de cristallite d'environ 4,08 nm et la microstructure d'environ 2,07% ont été obtenues pour 20 heures de broyage. Les microscopes électroniques à balayage (MEB) et l'analyse EDX ont confirmé le raffinement des particules broyées en fonction du temps de broyage et de l'homogénéisation de nos poudres. L'identification de phase a également été étudiée par un calorimètre DSC dans lequel des pics de changement de phase ont été identifiés. La caractérisation magnétique a été étudiée à l'aide d'un magnétomètre à échantillon vibrant (VSM); les résultats magnétiques optimaux sont obtenus après 20 heures de broyage; la température élevée VSM indique que le matériau traité commence à perdre progressivement ses qualités magnétiques à T = 80 ° C. Au-delà de la température de Curie, le matériau est considéré comme démagnétisé. Tous les résultats trouvés ont été commentés et discutés. Au-delà de la température de Curie, le matériau est considéré comme démagnétisé. Tous les résultats trouvés ont été commentés et discutés. Au-delà de la température de Curie, le matériau est considéré comme démagnétisé. Tous les résultats trouvés ont été commentés et discutés.
Preparation and Characterization of Ha/Gel/β-TCP Microspheres Composite Porous Scaffold
Authors: Zhao Yang Zi , Wang You Fa
Published: November 2018

Being one of the three elements of tissue engineering, three-dimensional porous structure scaffold plays an important role in tissue engineering. As it not only prvovide cells for the life, but also serves as a template to guide tissue regeneration and control of organizational structure and other functions. In this study, hyaluronic acid and gelatin are successfully cross-linked by 1-ethyl- (3-dimethylaminopropyl) -carbodiimide hydrochloride (EDC) , and compound β-TCP microspheres to prepare porous hydrogel scaffolds. The microspheres were analyzed by X-ray diffraction (XRD). The scaffolds were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). At the same time, the compressive strength, swelling ratio, degradation of the scaffold were tested. To assess the in vitro cell compatibility of the scaffolds, mouse L929 fibroblasts were seeded onto scaffolds for cell morphology and cell viability studies. The results showed that the pore size of the porous scaffold can be adjusted by changing the ratio of gelatin to hyaluronic acid (HA), increasing the proportion of hyaluronic acid in a certain range, pore size will be significantly increased. With the increase of the proportion of hyaluronic acid in the scaffold, the swelling ratio and the degradation rate also increased. The compressive strength of the scaffold increased with the increase of the proportion of gelatin. The appropriate ratio of β-TCP can promote cell growth and proliferation.
Changes in Surface Condition during Fabrication Process of Bioactive Apatite Nuclei Incorporated PEEK
Authors: Yabutsuka Takeshi , Hiruta Tomoko , Takai Shigeomi , Yao Takeshi
Published: November 2018

We aimed to clarify the effect of sulfuric acid treatment and oxygen plasma treatment on changes in surface condition of PEEK substrates during fabrication process of bioactive apatite nuclei (AN) precipitated PEEK. We treated PEEK substrate by sulfuric acid treatment. This treatment contributed to provide micropores and sulfo groups on the surface of the PEEK. Next, we treated the PEEK with oxygen plasma at 200 W for 4 minutes. By this treatment, both generation of carboxyl groups and increase of sulfo groups were occurred and significant improvement of hydrophilicity of the surface of the PEEK was occurred. Finally, we precipitated AN on the surface of the PEEK. By this treatment, high apatite-forming ability was achieved.
Wettability and Durability of Si-O Coatings on Zirconia Substrate by RF-Magnetron Plasma Sputtering
Authors: Yokogawa Yoshiyuki , Morishima Taishi , Uno Mitunori , Kurachi Masakazu , Doi Yutaka , Kawaki Harumi , Hotta Masato
Published: November 2018

The wettability and durability of Si-O coatings prepared on zirconia substrate using radiofrequency magnetron sputtering (rf-sputtering) was studied. XRD analysis revealed no phase transformation of zirconia before/after rf-sputtering process. XPS spectroscopy showed that as-deposited films with a SiO2 configuration was formed. EDX analysis indicated that the Si/Zr ratio was high and when magnetron rf-sputtering was performed using a plasma gas Ar+5% O2, which may be the optimum condition of rf-sputtering to form a sustainable hydrophilic layer on zirconia substrate. The wear testing using pin on disc wear apparatus was performed. The wettability and durability of Si-O coatings fabricated by magnetron radiofrequency magnetron sputtering (rf-sputtering) on zirconia substrate was studied. A plasma gas Ar+5% O2 may be the optimum condition of rf-sputtering to form a sustainable hydrophilic layer on zirconia substrate
Adhesion and Scratch Testing of Antibiotic Loaded Poly-Lactic Acid Biocomposite Thin Films on Metallic Implants
Authors: Karacan Ipek , Chou Joshua , Ben-Nissan Besim , Macha Innocent J. , Juritza Arion , Wang Andy H. , Müller Wolfgang H. , Grossin David , Taraschi Valerio , Oktar Faik Nuzhet , Swain Michael
Published: November 2018

Surface modifications have been progressively applied in order to improve the mechanical, biological and chemical properties of metallic dental and orthopedic implants. Therefore, the novel and multifunctional biocomposites coating matrices, which also consist of local and targeted drug delivery systems, are the most recent applications in the medical field. In this study, gentamicin antibiotic containing HAp bioceramics were utilized in a biodegradable poly-lactic acid thin film matrix which was applied to Ti6Al4V metallic implant surfaces. nanoindentation and scratch test methods were applied. It was observed that, bonding between coating and the substrate is strong enough to be used in implant applications. Additionally, it was observed that the hardness and young modulus values of uncoated Ti6Al4V disc which were 4.3 and 125.2 GPa, respectively. However, under the same testing conditions, it was also observed that the H values (0.6-0.8GPa) and the E (50-60 GPa) values of PLA-HAp biocomposite coated samples are slightly higher than the H values (0.4-0.6 GPa) and the E values (40-50GPa) of only PLA coated sample.
MC3T3-E1 Cellular Response and Protein Detection on Surface Potential-Controlled TiO2 Scale in Serum-Containing Medium
Authors: Hashimoto Masami , Ogawa Takafumi , Kitaoka Satoshi , Muto Shunsuke , Furuya Maiko , Kanetaka Hiroyasu , Abe Masayuki , Yamashita Hayato
Published: November 2018

MC3T3-E1 cell differentiation and related surface potentials of rutile-type TiO2 scales formed on Ti are controlled by varying the Ti heat treatment conditions in a N2 atmosphere containing a trace amount of O2. The zeta potentials of the samples heated at 873 and 973 K for 1 h show large negative and positive values, respectively, while cell differentiation on the surface is enhanced in both cases (14 days incubation). In the case of untreated Ti, the cell differentiation diminishes and the zeta potential becomes more neutral. Protein detection by an immunogold-labeling technique and Ca and P detection by time-of-flight secondary ion mass spectrometry reveal that Ca and P, rather than an adhesive protein such as fibronectin, predominantly adsorbed on the scales formed in 1 h at 873 and 973 K, respectively. In the case of untreated Ti, both fibronectin and a non-adhesive protein such as albumin adsorbed, but no Ca and P were detected. The present findings illuminate the relationship between charged surfaces and MC3T3-E1 cellular response.
VSC Adsorptive Property of Zinc or Iron Oxide in Comparison with that of Layered Double Hydroxide Containing Zinc of Iron
Authors: Yokogawa Yoshiyuki , Kakehashi Kodai , Wakabayashi Hidemitsu , Oike Kazuki , Morita Yuki , Fujii Kazuo , Hotta Masato , Doi Yutaka
Published: November 2018

Bad breath is mainly caused by malodorous materials, volatile sulfur compounds (VSC), hydrogen sulfide (H2S). Pharmaceutical drugs should be effective but limited, because bacteria at deep periodontal pocket may be sterilized but cannot be washed out and the malodorous compounds remain. The absorbents for the malodorous compounds are expected to prevent the teeth from decaying and peiodontics disease. The layered double hydroxides, of which composition is A1-xBx(OH)2Cx/n·mH2O, where A and B are zinc and Fe ions are effective as the absorbents for VSC. The VSC adsorption capabilities of zinc or iron oxide in comparison with that of layered double hydroxides containing zinc or iron ion. The high capacity of sulfide adsorption of layered double hydroxide may be due to the large number of adsorption sites of layered double hydroxide materials. The layered double hydroxides (LDH) have a structure favorable for ion or free molecules exchange, and high affinity with sulfide may be involved in iron or zinc containing LDH materials.
A Histological Assessment of the Mechanism of Early-Stage Healing of a Biphasic Calcium Phosphate in an In Vivo Rabbit Model
Authors: Dunkley Ian R. , Vickers Scott M. , Badura Jeffrey , Toth Jeffrey
Published: November 2018

The healing mechanism of osteoconductive biphasic calcium phosphate granules was investigated by a histological assessment of early-stage bone deposition and remodeling. The deposition of de novo bone on the scaffold granules was observed to initiate at the defect periphery by week one and in the bulk of the defect incorporating the granules by week four. New bone tissue was deposited in the space provided by the macroporosity and was observed in direct apposition to the implanted material confirming the bioactivity of the biphasic calcium phosphate. The granules were removed through a cell-mediated resorption process that was observed to begin as early as week two following surgery. Mature lamellar bone, fatty bone marrow, and vascularization was observed throughout the bulk of the defect with the cortical shell healed by week twelve. This healing mechanism was found to balance bone formation and implant resorption resulting in complete healing of the corticocancellous defect in the rabbit femoral condyle.
Evaluation of Elution Behavior of Silver Ions from Silver-Containing Carbonate Hydroxyapatite Composites
Authors: Murakami Takayuki , Noda Iwao , Ikeda Junji , Nakahira Atsushi
Published: November 2018

Infection related to orthopedic implant surgeries is one of the significant postoperative complications. Recently, many studies have been conducted on silver-containing hydroxyapatite (AgHA) composites as antibacterial and osteoconductive biomaterials to prevent postoperative infection. In this study, we prepared 1 and 10 wt% Ag-containing carbonate hydroxyapatite composites (1AgCHA and 10AgCHA, respectively) by solid-phase reaction, and investigated the relation between the elution rate of Ag ions from the composites and the chemical or physical states of Ag in AgCHA. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results indicated that metallic Ag particles disappeared in 1AgCHA heated at 800°C, whereas they were distributed in 10AgCHA heated at all temperatures. The amount of A-type CO32- group in AgCHA structure drastically increased at 800°C, but decreased with increasing amount of Ag. The lattice constant (a-axis) of hydroxyapatite expanded drastically when heated at 800°C, and with increasing Ag content, the extent of expansion of a-axis decreased as well as amount of A-type CO32- in CHA. Moreover, after the 48-h elution test, the concentration of Ag+ released from 10AgCHA heated at 800°C was less than 0.1% of total Ag amounts, while 1AgCHA heated at 800°C released over 0.8% of total Ag amounts. The results indicate that Ag+ and CO32- were substituted competitively into the Ca2+ and OH- sites of HA, respectively, after heating at 800°C, and that the elution rate of Ag+ from the sites of Ag+-substituted CHA was faster than that from metallic Ag particles. A better understating of the elution behavior of Ag from AgCHA is important for controlling the physical and chemical states of Ag in composites.
Theoretical Investigation of the Shubnikov-de Haas Magnetoresistance Oscillations in a Quantum well under the Influence of Confined Acoustic Phonons
Authors: Hung Le Thai , Thang Pham Ngoc , Bau Nguyen Quang
Published: November 2018

The Shubnikov – de Haas magnetoresistance oscillations in the Quantum well (QW) under the influence of confined acoustic phonons, The theoretical results show that the conductivity tensor, the complex magnetic impedance of the magnetic field, the frequency, the amplitude of the laser radiation, the QW width, the temperature of the system and especially the quantum index m characterizes the confinement of the phonon. The amplitude of the oscillations of the Shubnikov-de Haas impedance decreases with the increase of the influence of the confined acoustic phonons. The results for bulk phonons in a QW could be achieved, when m goes to zero. We has been compared with other studies when perform the numerical calculations are also achieved for the GaAs/AlGaAs in the QW. Results show that The Shubnikov-de Haas magnetoresistance oscillations amplitude decrease when phonon confinement effect increasing and when width L of the QW increases to a certain value, The Shubnikov – de Haas magnetoresistance oscillations amplitude completely disappears can not be observed.
Study on Adsorption of Mercury from Aqueous Solution on Activated Carbons Prepared from Palm Kernel Shell
Authors: Abdullah Nor Salmi , Sharifuddin Syazrin Syima , Hussin Mohd. Hazwan
Published: November 2018

The adsorption ability of powdered activated carbons (PAC) derived from palm kernel shell (PKS) was investigated. PAC was prepared by chemical activation method using ZnCl2as an activating agents. The adsorption studies of Hg(II) was carried out under control condition with constant pH, solution temperature (30 °C), treatment time (90 min) and absorbent dosage (2.0 g L-1). It was revealed that PAC efficiently removed as much as 10 mg L-1of Hg(II) with the percentage of removal up to 97.7 %. Both Langmuir and Freundlich adsorption isotherms were used to explain the adsorption behavior. Freundlich model was found to be fitted well and favored multilayer adsorption. The kinetics data were fitted with pseudo-first order and pseudo-second order, and it was found to obeys the pseudo-second order kinetic order. Recent finding suggest that PKS has the potential to be a promising precursor for the production of activated carbon with the excellent adsorption capacity to remove Hg(II) from aqueous solution.
Three-Dimensional ES Barrier Promotes the Steps Formation
Authors: Yang Jin , Zhou Ya Jun , Pu Bing Xue
Published: November 2018

Physical vapor deposition (PVD) has been an important method to synthesize metallic nanorods during the past two decades. Based on the main physical process of crystal growth, this letter made a growth model of metallic nanorods with kinetic lattice Monte Carlo (KLMC) method and studied the effects of three-dimensional (3D) Ehrlich–Schwoebel (ES) barrier during the metallic nanorods growth. According to the simulation results, a large 3D ES barrier affects the surface morphology apparently. With analyze the simulation results, 3D ES barrier promotes the step formation and increases the step height greatly, and it is the main factor of metallic nanorods formation.
On the Latest Development of some Typical Cathode Materials for Lithium Ion Battery
Authors: Zhang Yong Tao , Hu Xiao Li
Published: November 2018

The lithium-ion battery is widely and increasingly used in many portable electronic devices and high-power systems in the modern society. Currently, it is significant to develop excellent cathode materials to meet stringent standards for batteries. In this paper, recent developments were reviewed for several typical cathode materials with high voltages and good capacities. These cathode materials referred to LiCoO2, LiNiO2, LiMn2O4, LiMPO4 (M=Fe, Mn, Co and Ni, et al), and their composites. The technical bottlenecks about the cathode material is required to be conquered. For instance, LiCoO2 and LiNiO2 have high coulombic capacity and good cycling characteristics, but are costly and exhibit poor thermal stability. Simultaneously, LiMn2O4 exhibit good thermal stability, high voltage and high rate capability, but have low capacity. Thus it is advantageous to produce a composite which shares the benefits of both materials. The composite cathode material is superior over any single electrode material because the former has more balanced performance, and therefore, is promising to manufacture the next generation of batteries.
Finite Element Analysis of Incremental Sheet Forming for Metal Sheet
Authors: Sajjad Muhammad , Joy Jithin Ambarayil , Jung Dong Won
Published: November 2018

Incremental sheet metal forming, is a non-conventional machining process which offers higher formability, flexibility and low cost of production than the traditional conventional forming process. Punch or tool used in this forming process consecutively forces the sheet to deform locally and ultimately gives the target profile. Various machining parameters, such as type of tool, tool path, tool size, feed rate and mechanical properties of sheet metal, like strength co-efficient, strain hardening index and ultimate tensile strength, effects the forming process and the formability of final product. In this research paper, Single Point Incremental Forming was simulated using Dassault system’s Abaqus 6.12-1 and results are obtained. Results of sheet profile and there change in thickness is investigated. For this paper, we simulated the process in abaqus. The tool diameter and rotational speed is find out for the production of parts through incremental forming. The simulation is done for two type of material with different mechanical properties. Various research papers were used to understand the process of incremental forming and its simulation.
Simulation of Crack Propagation in Concrete Based on Extended Finite Element Method
Authors: Tang Yu Xiang , Chen Hong Niao
Published: November 2018

Fracture behaviors in concrete beam subjected to three-point bending was numerically simulated using extended finite element method (XFEM). The entire load-displacement curves and crack path obtained by numerical simulation were compared with that measured from experimental tests. Compared with the experimental results, the errors of numerical Pc and δc were smaller than 10% and the error of CMODc was lower than 2%, verifying the validity and accuracy of XFEM model. Whether a XFEM simulation or a test, the propagation direction of the main crack is toward to the upper loading point. At the peak load, the crack lengths measured by ESPI and XFEM were 93 μm and 97 μm respectively.
Hydrochemistry Research of Intercrystalline with Pore Brine and Pre-3D Modelling of Heibeiwadi Brine Deposit
Authors: Song Huang
Published: November 2018

Intercrystalline and pore brine develop extensively in the Heibewadi research area which is located at south foot of Altun mountain of Qaidam basin. In central area, intercrystalline brine’s depths range from 5m to 90m. In northwest, south area and central deeper area, pore brine develops under intercrystalline brine layer. The 2 types of aquifers have strong yield property, TDS is 200-350g/l with average of 276g/l. Main salt compound can be mined out economically. According to analysis result of intercrystalline brine, TDS, Cl-, Na+, K+, Mg2+, Li+ irons’ grades are very steady. That mean intercrystalline brine exist in the water-salt system under balance. Only the stability of Ca2+ and SO42- are slightly poor. According the Kurtosis characteristics analysis, Ca2+, SO42- are no-normal positively platykurtic distribution, K+, Cl- and PH are normal positively platykurtic distribution. These 2 groups fall into a sub-class. And the combined with normal negatively platykurtic distribution-TDS and fall into platykurtic distribution group. Mg2+, Li+ are normal positively peaked distribution; Na+ is normal negatively peaked distribution. They all belong to peaked distribution group. According to Na+, K+, Mg2+//Cl-H2O quarternary phase diagram and Na+, K+, Mg2+//Cl-SO42-H2O pentabasic phase diagram, the chlorite and magnesium sulfate subtype have different hydro chemical characteristics and salting-in and salting-out rules.
Blown Film of m-LLDPE Using a Novel Eccentric Rotor Extruder
Authors: He He Zhi , Liu Shi Ming , Cheng Lan Ya , Ni Yi Ping , Xue Feng , Xue Bin , Huang Zhao Xia , Zhu Zhi Wen , Liu Bi Da , Chen Qing Hua , Chen Deng Long
Published: November 2018

Metallocene linear low-density polyethylene (m-LLDPE) has superior physical and mechanical properties. While, the film blowing processability of m-LLDPE was very poor when processed under shear flow. To overcome this drawback, a novel device based on elongational flow was self-developed to process m-LLDPE. In order to investigate the effect of elongational flow on the processability improvement of m-LLDPE, five types PE were studied in this paper. All kinds of PE were prepared using this novel device and traditional single-screw extruder with molecular weight and its distribution, mechanical properties and WAXD characterization. Gel Pemeation Chromotographer (GPC) data shows that molecular weight of each resin prepared using this novel eccentric rotor extruder (ERE) is higher than that processed by traditional single screw extruder (SSE). Mechanical properties showed that tensile properties of all kinds of films blowing from ERE is better than the one from SSE. However, tear properties of m-LLDPE films made from ERE differ from LDPE or LLDPE. And had a relative low value than the one made from SSE. In addition, Wide-angle X-ray Diffraction (WAXD) results indicate that films blowing from ERE exist a partially ordered component in addition to the usual crystalline and amorphous components which can’t be achieved from SSE.
The Effects of Geosynthetic-Reinforcement on Consolidation Behavior of Soft Clay Embankment under Step Construction
Authors: Gao Yu Cong , Chen Rong , Hao Dong Xue , Won Myoung Soo
Published: November 2018

Geosynthetics–reinforced structures are widely used in embankments and walls. This paper presents the simulation of the embankment under load in order to compare the behavior of clay embankment with and without wrapping-facing-geosynthetics-reinforcement using finite element method (FEM) and to analyse the variation of behavior included of displacement and excess pore pressure under the different over-consolidation ratios (OCR). The calculation results show that embankment with higher OCR showing lower displacement compare to embankment with lower OCR. However, OCR isn’t very sensitive to the dissipation of excess pore pressure. Geosynthetics-reinforcements could reduce the displacement of embankment and accelerate dissipation of excess pore pressure after construction and surcharge. Gravel, geosynthetics-reinforcement and clay soil are properly combined, clayey soil is expected to be useful as embankment material.
Interaction of External Acoustic Waves - Confined Electrons - Internal Phonons in a Cylindrical Quantum Wire with an Infinite Potential in the Presence of an External Magnetic Field
Authors: Nhan Nguyen Vu , Nghia Nguyen Van , Thang Nguyen Quyet , Bau Nguyen Quang
Published: November 2018

Interaction of external acoustic waves - confined electrons - internal phonons in a cylindrical quantum wire with an infinite potential (CQWIP) has been theoretically studied via the quantum kinetic equation for electrons in the presence of an external magnetic field (EMF). The quantum kinetic equation for the distribution function of electrons interacting with internal and external acoustic phonons is obtained from the Heisenberg equation of motion and the model of CQWIP. The density of acoustomagnetoelectric (AME) current and the analytical expressions for the AME field in the CQWIP in the presence of the EMF are obtained. The theoretical results are numerically evaluated for the specific CQWIP of GaAs/GaAsAl. It is shown that the AME field strongly depends on the system temperature in both cases of the strong magnetic field and the weak magnetic field. However, the graph showing the relationship between the AME field and the system temperature has the peaks in case of the strong magnetic field. The reason may be due to movement of the electrons between the mini-bands. The AME field obtained in this work are then compared with those of bulk semiconductors, superlattices, quantum wells (QW) and rectangular quantum wire (RQW).
Research on Numerical Simulation of Gas Flow in Shale Matrix Micro Pore
Authors: Cao Zong Xiong , Yu Xing Guo , Xiang Kui
Published: November 2018

In view of Longmaxi shale core in Sichuan basin, two-dimensional images of shale core were given by using scanning electron microscopy (SEM), and processed by ImageJ software to reconstruct the 3D shale matrix digital core, the digital core can reflect the nano pore structure more accurately. LBM model of gas flow in shale porous medium is established based on lattice Boltzmann method. The corresponding boundary conditions were established based on slip phenomenon for shale gas in porous medium micro flow, which can simulate gas flow in the micro pore in shale more realistic. The numerical results show that the microscale effect becomes obvious with the increase of Knudsen number, and the more obvious the non-Darcy phenomenon of gas flow in the shale matrix. The research results of this paper provide a theoretical basis for shale matrix permeability calculation, shale gas well productivity evaluation and development scheme design.
Theoretical Study of the Magneto-Thermoelectric Effect in Doped Semiconductor Superlattices under the Influence of an Electromagnetic Wave by Using a Quantum Kinetic Equation
Authors: Hang Dao Thu , Nhan Nguyen Vu , Bau Nguyen Quang
Published: November 2018

By using a quantum kinetic equation for electrons, we studied magneto - thermoelectric effects in the doped semiconductor superlattice (DSSL) under the influence of electromagnetic waves (EMW). In case of the electron - acoustic phonon interaction, we have also figured out analytical expressions of the Ettingshausen coefficient (EC) in DSSL. These expressions are quite different from those which were obtained in the case of bulk semiconductors. The results are numerically calculated for the GaAs:Be/ GaAs:Si DSSL; we found that the EC depends on the characteristic parameters of EMW, temperature and the characteristic parameters of DSSL. The results are consistent with recently experimental observations but the EC is different from that in the bulk semiconductors or bismuth. In addition, the impact of the EMW on the Ettingshausen effect was also discovered. These are latest results which have been studied in terms of Ettingshausen effect in DSSL.
Nanoindentation Characterization of Mechanically Alloyed Fe-Al-Si Powders
Authors: Haušild Petr , Čech Jaroslav , Karlík Miroslav , Průša Filip , Novák Pavel , Kopeček Jaromír
Published: November 2018

The effect of processing conditions on microstructure and mechanical properties of Fe-Al-Si powders was studied by means of scanning electron microscopy, X-ray diffraction and nanoindentation. Fe-Al-Si alloy powder was prepared from pure elemental powders by mechanical alloying. Microstructure and mechanical properties of powders were characterized after various durations of mechanical alloying. Special sample preparation technique was developed allowing to characterize the properties of individual powder particles after each step of processing in a planetary ball mill. This step-by-step characterization allowed to find the optimum conditions for subsequent spark plasma sintering.
Local Mechanical Properties of Zinc-Iron Coated Steel Sheets by Depth-Sensing Indentation
Authors: Ambriško Ľubomír , Pešek Ladislav
Published: November 2018

Depth-sensing indentation (DSI) is used in this work to determine the change of local mechanical properties by annealing of hot-dip galvanized IF steel sheets. The influence of annealing conditions (temperature and time) on: (i) coating composition; (ii) local mechanical properties and (iii) roughness of the coating surface was quantified. Annealing of steel samples (Ti-IF steel and Ti-Nb-P-IF steel alloyed with phosphorus) was performed with different holding times (10, 60, and 300 s) by both temperatures 450 and 550 °C. The zinc in coating transformed during annealing to the intermetallic phases ZnxFey. Annealed Zn-Fe coatings, wherein the iron concentration falls towards the surface, consist of different intermetallic phases.
Study of Local Mechanical Properties of Fe78Al22 Alloy
Authors: Buršíková Vilma , Homola Vojtěch , Jirásková Yvonna , Pizúrová Naděžda , Miháliková Ivana , Friák Martin , Koutná Nikola , Slávik Anton , Holec David , Šob Mojmír
Published: November 2018

The local mechanical properties of Fe78Al22 alloy were studied using nanoindentation techniques. Sharp Berkovich indenter was used to perform load-controlled nanoindentation experiments on the studied sample. Hardness and elastic modulus maps were created on the basis of the indentation tests carried out in different grains. The focus of the work was to study the dependence of mechanical properties on the grain orientation. The results were in good agreement with quantum-mechanical calculations of anisotropic elastic properties of the studied alloy. It was explained that the maximum detected elastic modulus values are likely for grains with [111] crystallographic orientations which we theoretically identified as the hard ones.
Micromechanical Properties of UHMWPE’S with Different Molecular Weights
Authors: Slouf Miroslav , Krejcikova Sabina , Hromadkova Jirina , Vlkova Helena
Published: November 2018

Ultrahigh molecular weight polyethylene (UHMWPE) is used as a key component of total joint replacements (TJR) and its mechanical performance is one of the factors influencing TJR lifetime. Micromechanical properties of three model UHMWPE samples with different molecular weights were evaluated from both non-instrumented and instrumented microindentation hardness testing. The properties were correlated with molecular and supermolecular structure of the samples. We have demonstrated that molecular weight influenced the final micromechanical properties mostly indirectly – it changed the overall crystallinity, which strongly correlated with microhardness, indentation modulus, and also with the elastic part of the indentation work. Only microcreep was influenced predominantly by amorphous phase, in which the higher molecular weight resulted in higher amount of entanglements and slightly higher creep resistance.
Effect of Different Factors on Measured Values of Indentation Hardness of Interstitial Free Steel by Depth Sensing Indentation
Authors: Burik Peter , Pešek Ladislav , Andršová Zuzana , Kejzlar Pavel
Published: November 2018

Nanomechanical testing using depth sensing indentation (DSI) provides a straightforward solution for quantitatively characterizing each of phases in microstructure because it is very powerful technique for characterization of materials in small volumes. Measuring the local properties (indentation hardness HIT, indentation modulus EIT, indentation energy: total Wtotal, elastic Welast, plastic Wplast) of each microstructure component separately in multiphase materials gives information that is valuable for the development of new materials and for modelling. The mechanical properties of materials measured by DSI are affected by the experimental procedure, by the measurement conditions and factors which result from the material characteristics and device construction. We have to determine the effect of individual factors on the measurement in order to reach the repeatability and to allow the comparing the mechanical properties of the material. The aim of this investigation is to determine the measurement factors that affect indentation hardness of individual microstructural components and global mechanical properties of thin steel sheets. We investigated the factors which result from the material characteristics (crystallographic orientation of grain, grain boundary and anisotropy), preparation of the sample surface (roughness of sample surface) and method of measurement (pile-up, ISE).
Characterization of Brittle Phase in Magnesium Based Materials Prepared by Powder Metallurgy
Authors: Krystýnová Michaela , Doležal Pavel , Fintová Stanislava , Zapletal Josef , Marada Tomas , Wasserbauer Jaromír
Published: November 2018

Magnesium-zinc based materials are characteristic with the creation of intermetallic phases, strongly influencing material mechanical properties. Mg-Zn powder mixture (10 % wt. Zn) was processed by the hot pressing method under 500 MPa at 300 °C. Microstructure of the prepared material was analyzed in terms of light optical microscopy and scanning electron microscopy. Chemical and phase composition of the processed material were analyzed by energy-dispersive X-ray spectroscopy and X-ray powder diffraction, respectively. Microhardness testing was adopted to characterize created structure mechanical properties on the microscopic level. Depending on the Mg-Zn powder mixture local chemical composition, the structural and chemical analysis of the processed material revealed that it consisted of magnesium and zinc rich areas, and MgZn2 intermetallic phase. The MgZn2 intermetallic phase belongs to the so-called Laves phases group with the general formula AB2. Laves phases are characteristic with high hardness and the related high brittleness. Their presence in the material usually results in deterioration of mechanical properties such as strength and toughness. The microhardness of magnesium and zinc rich areas in the processed material was 58±1 HV 0.025 and 47 ±1 HV 0.025, respectively, while the value of the microhardness for MgZn2 intermetallic phase was 323±12 HV 0.025. Different behavior and mechanical properties of the present phases was observed on the fracture surfaces of specimens broken during the 3-point bend test. While brittle fracture was a characteristic feature for MgZn2 intermetallic phase, the rest of the material exhibited more ductile fracture behavior with characteristic transgranular failure.
Thermal Shock Resistance of Si3N4/hBN Ceramic Composites
Authors: Kovalcikova Alexandra , Húlan Michal , Sedlák Richard , Fides Martin , Balázsi Csaba , Mihaliková Mária , Dusza Jan
Published: November 2018

Si3N4/hBN composites were fabricated by hot isostatic pressing at 1700°C/3h with 1, 3 and 5 wt. % micro-sized or nano-sized hexagonal boron nitride particles added to silicon nitride matrix. An indentation quench test method was used for estimation of thermal shock resistance of monolithic Si3N4 and Si3N4/hBN composites. Thermal shock resistance of the composites increased with the increase of size and volume of hBN particles. The critical temperature difference for the composites with micro-sized hBN was significantly higher (over 900°C) compared to the monolithic silicon nitride (580°C).
Influence of Interfacial Transition Zone on Local and Overall Fracture Response of Cementitious Composites
Authors: Zacharda Vojtěch , Němeček Jiří , Šimonová Hana , Kucharczyková Barbara , Vyhlídal Michal , Keršner Zbyněk
Published: November 2018

Mechanical fracture properties of interfacial transition zone (ITZ) of fine-grained composite based on cement matrix with different types – basalt, granite, marble and amphibolite – of rock inclusion were studied. Specimens with the initial stress concentrator were tested in standard three-point bending configuration. Fracture surfaces were examined with light and electron microscopes. Local ITZ response was characterized by nanoindentation in the vicinity of rock inclusions. Local elasticity, hardness and viscous properties were assessed. It has been shown that the ITZ is mechanically weaker compared to the bulk matrix in the region of ca. 0–20 μm from the inclusion for all specimen’s types. It exhibits gradual increase of elastic modulus and hardness, which can be approximately expressed by a power law. On the other hand, the creep in ITZ was found to be higher compared to the bulk matrix. The results of nanoindentation measurements are in a good agreement with overall mechanical properties, fracture response and microstructure measurements done by scanning electron microscopy.
Microseismic Multistage Formation Hydraulic Fracturing (MFHF) Monitoring Analysis Results
Authors: Aleksandrov Vadim , Kadyrov Marsel , Ponomarev Andrey , Drugov Denis , Bulgakova Irina
Published: November 2018

Microseismic monitoring of hydrocarbon fields is one of the promising areas of modern seismology. In recent years, the methodology of microseismic monitoring for seismic emission has been actively developing in the oil and gas industry in order to study the impact of various technogenic processes on the hydrocarbon (HC) fields being developed. The technology does not require powerful sources of sounding signals, but uses constantly existing weak seismic fields of artificial or natural origin. During the development of the field, periodic monitoring of the intensity and spatial position of the zones of microseismic activity allows controling the behavior of HC deposits in order to optimize their development. Distinctive features of this technology are high mobility, fast deployment time, high resolution, and low cost of receiving, transferring and processing of microseismic data. The purpose was to analyze the results and evaluate the effectiveness of MFHF using microseismic monitoring of seismic emission processes. The results were obtained with the help of quantitative microseismic monitoring of seismic foci occurring successively near the well ports at different times during MFHF.
The Mature Formation Production Features
Authors: Aleksandrov Vadim , Kadyrov Marsel , Ponomarev Andrey , Golozubenko Vadim , Kopyrin Vladimir
Published: November 2018

The mature stage of field production is reported to observe a significant decline in oil production rates; watercut either grows slowly or (with the regulation of the production processes) somewhat stabilizes. In some periods, it even somewhat decreases, usually due to the cut-off of the highly watered well stock. During the multi-foundation field production, joint exploitation of the productive foundation is often applied; these foundations are often allocated to different sites. The research objective is to justify the directions for further production of the geological and commercial site, which is at the mature production stage; choose the most technologically "productive" and economically feasible interventions in order to increase oil recovery. Applying the classical methods of geological-field analysis and calculation of displacement characteristics, the main trends in the field production have been revealed; using the data of field and geophysical research, the reasons for obtaining unsatisfactory results in joint foundation operation have been revealed.
Peculiarities of the Geological Structure of the Roslavl License Block
Authors: Aleksandrov Vadim , Kadyrov Marsel , Markov Alexander , Golozubenko Vadim , Sivkov Yuriy
Published: November 2018

The Roslavl license block is one of the main assets of "RussNeft" company. Some particular perspectives of enhancing oil recovery are connected with this territory. The work objective was to define the perspectives of geological exploration, find new hydrocarbon deformational traps, and specify the geological structure of the already-known oil reservoirs in the Neocomian sediments, the Achimov strata, and Middle Jurassic sediments. The data analysis is necessary to create a new promising exploitation drilling program. The Roslavl license block is considered to be one of the most difficult and interesting areas in the sphere of hydrocarbon saturation perspectives from the quantitative aspects viewpoint. Different expectations on enhancing oil recovery in the Middle Ob oil and gas province of West Siberia are connected with this license block. Therefore, these perspectives were evaluated with the help of deep analysis of shooting data collected by seismic crews in different years, and the results of drilling. Different archival geological and geophysical evidence was analyzed to offer recommendations on the following geological exploration.
Diagnostics of Facial Complexes in Bajocian-Bathonian Deposits of the Peschanoye Field
Authors: Aleksandrov Vadim , Kadyrov Marsel , Ponomarev Andrey , Drugov Denis , Veduta Olga
Published: November 2018

The establishment of the paleofacial nature of sand bodies is of an utmost importance in the search for lithological traps of oil and gas, and also allows forecasting their spatial location, the position of wedging zones and changes in the reservoir properties of reservoir units. The research objective is to determine the genesis of productive deposits of the Bajocian-Bathonian age and to reveal the features of their geological structure. With the help of facial and electrometric methods of research, facies complexes were identified in deposits of the Bajocian-Bathonian age.
Geodynamic and Lithofacies Features of Deposit Formation of the AV11-2 Horizon of the Samotlor Field
Authors: Aleksandrov Vadim , Kadyrov Marsel , Ponomarev Andrey , Drugov Denis , Zapevalov Vladimir
Published: November 2018

An era of a high-gravity oil of the Samotlor field formations AV2-5 and BV8-10 is near to its end. The production deposits of the AV11-2 horizon are the main reserve of oil production and the basic prospect in this area. Stratigraphically, the AV11-2 horizon belongs to the Alym suite of the early Aptian Age that was distinguished as an individual unit at the 1967 interdepartmental stratigraphic meeting with the stratotype in the Uvat test well. This part of the section started to form around 400,000 years ago and is represented by siltites with interlays of clays and sandstones, primarily bioturbated ones, which causes the specific lens-clustered laminarity of these rocks (Ryabchik) with rare double leafs and single pancake-shaped primitive foraminifers such as saccamina. Specific features of the geological structure and oil-and-gas content of the AV11-2 horizon within the area under consideration were in various aspects described earlier in the works of many researchers [1-8]. Nevertheless, when new geological and geophysical information had been accumulated, the need arose to cover this issue once again. Since it makes us consider the geological modeling of formations in the horizon from quite a different angle, we need to create various structural models of HC reservoirs, development flow diagrams, etc. The research objective is to define the genesis of producing deposits of the AV11-2 horizon and identify fascia complexes in them. Using a system of special studies and methods for analyzing geological development and structure (paleotectonic, grain size, fascia, electrometric, etc.), the areas of sedimentation and fascia systems were diagnosed within the area under research.