bluuebunny/crossref_metadata_2025 huggingface dataset:
The microstructure and mechanical properties of silicon carbide fibers with boron nitride interphase
Authors: Lv Xiaoxu , Qi Zhe , Jiang Zhuoyu , Zhou Yiran , Zhao Wenqing , Jiao Jian
Published: November 2019

The 2nd generation SiC tows is a type of essentially polycrystalline fibers (SiC1.46O0.03). Smooth and uniform boron nitride interphase was deposited on SiC fibers by low pressure chemical vapor infiltration (CVI). The scanning electron microscopy(SEM) was used to characterize the microstructure of the BN interphase and fibers while X-ray diffraction(XRD) and TEM were used to characterize the phase constitute of the fibers. The XRD and TEM results showed that the BN interphase prepared by CVI is turbostratic. The effects of thickness on the mechanical properties of SiC fibers were investigated by using two-parameter Weibull distribution. The fibers with thin BN interphase showed higher strength than the as-received fibers, for healing the surface flaws. However, the soft nature of increasing BN thickness had a more dominant effect and resulted in the decrease of fiber strength.
Effect of Carrier Gas on the Conversion Process of BN Organic Polymer Precursor to BN Ceramic
Authors: Chen Mingwei , Qiu Haipeng , Xie Weijie , Zhang Bingyu , Liu Shanhua , Luo Wendong , Ma Xin
Published: November 2019

Boron nitride organic polymer precursors were pyrolyzed under different carrier gases such as NH3, Ar and N2. The conversion process of BN organic polymer precursor to BN ceramic was characterized by means of TG, FTIR, and elemental analysis. Results showed that NH3 could promote conversion process which was beneficial to the occurrence of hydrolysis, crosslinking and decomposition reaction. Therefore, lower carbon residue existed and more regular inorganic structure were obtained in boron nitride precursor pyrolytic products which would be helpful to gain BN fiber with excellent wave transparent properties.
Preparation and Properties of Cf/SiC-ZrC Ultrahigh Temperature Ceramic Matrix Composites
Authors: Wang Yanyan , Zhai Lingyu , Li Xiaobo , Xing Zhengpeng , Gong Xiaolin , Chen Pengyu , Qingsong-Xie
Published: November 2019

Ultra-high temperature materials have many excellent properties, such as high melting point, high specific strength, high thermal conductivity, high conductivity, corrosion resistance and good chemical stability, which make them become high temperature structural materials for aircraft in extreme environments.Cf/SiC-ZrC ultra-high temperature ceramic matrix composites were fabricated by the combined process of chemical vapor deposition and precursor infiltration pyrolysis (CVI-PIP) in this study. The phase composition and microstructure features of the composites were characterized using X-ray diffraction, scanning electron microscopy. A PyC layer was observed as the interfacial layer between carbon fiber and the ultrahigh temperature ceramic matrix. It can protect the carbon fiber from damage during the cyclic PIP process. Nano crystalline ZrC particles were observed in the composites. The ablation mechanisms of the composites were tested in arc-jet wind tunnel and it exhibited good ablation-resistant properties. The ablation mechanism of composite materials in wind tunnel environment is discussed.
Oxidation Behavior of ZrB2-SiC Modified Zr3[Al(Si)]4C6 Composites Exposed to Air
Authors: Wang Xuhong , Liu Hui , Zhang Jianhao , Ji Wangjin , Shi Si , Hu Jian , Liu Yurui , Yu Lei
Published: November 2019

The oxidation behavior of Zr3[Al(Si)]4C6-matrix composites reinforced by adjusted content of ZrB2-SiC with fixed molar ratio of 2:1 was investigated. The composites were exposed to air at medium temperatures, and the oxidation kinetics of the composites generally follow a parabolic law. With the ZrB2-SiC content increasing from 0 to 40vol.%, the oxidation weight gain per unit surface area (Δw/s) and oxidation rate constant (k
p) of the specimens increase and then decrease at the same oxidation conditions. The high content of ZrB2-SiC is benefit for improving the oxidation resistance of the composites. And, the lowest k
p of the composite incorporated with 40vol.%ZrB2-SiC is about 2.43×10−6kg2·m−4·s−1 when oxidized at 1100°C, which is stillhigherthan that of monolithic Zr3[Al(Si)]4C6. In addition, the phase composition and microstructure of oxidation products and the oxidation mechanism of materials were analyzed and discussed.
Fabrication of Yb:Lu2O3 Transparent Ceramics by Hot Isostatic Pressing: the Effect of Yb Doping Concentrations
Authors: Dong Linlin , Ma Mingzhen , Jing Wei , Xu Tao , Kang Bin , Guo Ruisong
Published: November 2019

Highly transparent ytterbium doped lutctium oxide (Yb:Lu2O3) transparent ceramics with different Yb doping concentrations (0.5–10 at% Yb) were fabricated from commercial powders by vacuum sintering combined with hot isostatic pressing (HIP) method. The effects of Yb3+ doping concentrations on the microstructure, optical performance and the thermal conductivity of Yb:Lu2O3 transparent ceramics were investigated. The grain size of Yb:Lu2O3 ceramics first decreased with Yb doping concentration increasing and then kept nearly unchanged at high Yb doping concentrations. Under 1750°C HIP sintering for 2h, The in-line transmittance of the 5 at.% Yb:Lu2O3 ceramics (3 mm thick) exceeds 81.52% at 1100 nm. And it had the average grain size about 2μm. As the doping concentrations increase, the overall thermal conductivity decreases slightly. The fluorescence emission spectrum implied high possibility of realizing laser output at 1080 nm by pumping at 980 nm.
Luminescence Properties of Ce3+ Doped Garnet Ca2LaZr2Al3O12 Phosphors
Authors: Yu Ming , Wang Baochen , Liu Yan-gai , Wang Lu , Xia Yufei , Huang Zhaohui , Fang Minghao
Published: November 2019

A series of novel Ca2LaZr2Al3O12: xCe3+garnet phosphors were obtained by conventional high temperature solid-state reaction. Crystal structure, phase purity, micromorphology as well as luminescence properties are studied via X-ray powder diffraction, scanning electron microscope and photoluminescence spectra including excitation and emission. Moreover, the mechanism of concentration quenching, thermal stability, fluorescent lifetime and quantum efficiency were investigated in detail. Under n-UV excitation, Ca2LaZr2Al3O12: Ce3+ exhibits a broadband of blue emission at 440 nm approximately for maximum, corresponding to 5d-4f transition of Ce3+. Emission can keep 41% of initial intensity when temperature is promoted to 373 K according to temperature-dependence emission spectra. The internal quantum efficiency of the optimal specimen is 15% and with Ce3+ increasing, the color of emission transfers to light from dark blue at CIE.
Research on Oxidation Resistance of Silicon Carbide Refractories to High Temperature Steam
Authors: Xiang Y B , Guo A , Wang WW , Wan L G , Cao H Y , Huang Z G , Wang J P , Wu J G , Si Y C
Published: November 2019

Refractory linings of waste incineration plants based on oxidation resistant SiC materials enable a long service life at suitable firing and operation conditions. Steam oxidation resistance of Si3N4-SiC, SiO2-SiC, SiAlON-SiC material at 1000°C was tested according to ASTM-C863 after 50c, 100h, 200h, 250h and300h respectively. The phase composition and microstructure before and after oxidation were analyzed by means of XRD and SEM. Results indicate that there is continuous increase of volume expansion and weight change on materials with the oxidation to the oxidation time. After 50h of oxidation, a small amount of cristobalite can be observed in these materials, which comes directly from the oxidation of SiC, Si2N2O and SiAlON or from the crystallization of glass phase. Oxidation weight gain occurs in the first 50 h, but volume expansion takes place after 50h . Compared with the three materials, SiO2-SiC material has a smaller weight change and volume expansion. Comparing the SEM these three materials, it is obvious that SiO2-SiC material has a better density after 300h. Based on the above results, conclusions can be reached that: the sample of SiO2-SiC has better oxidation resistance and is more suitable as lining material of waste incinerator.
Effect of AlF3 Content on the Properties of In-situ Generated Mullite Whisker Reinforced High Aluminum Castables
Authors: Li Jijia , Luo Xudong , Xie Zhipeng , Yang Mengmeng
Published: November 2019

The mullite whiskers have excellent high temperature resistance and high heat characteristics, the melting point is above 2000°C, and the maximum use temperature is 1500°C to 1700°C. In this paper, mullite whiskers were prepared by in-situ growth method. High aluminum castables were prepared by injecting mullite whiskers in situ at high temperature by adding Al(NO3)3·9H2O and NH4F to high alumina castables. It is 0, 0.5 wt%, 1 wt%, 2 wt%, 4 wt%. The materials were mixed, stirred, cast, and demolded and then fired at 1400°C. By testing the bulk density, apparent porosity and residual flexural strength of the samples, the properties, microstructure and microstructure of the fired samples were analyzed and characterized by means of XRD and SEM. The study focused on AlF3 to mullite whiskers. The effect of microstructure and flexural strength. The results show that the introduction of AlF3 promotes the formation of mullite whiskers. With the increase of AlF3 content, the aspect ratio of whiskers increases first and then decreases, and when the AlF3 content is 1wt%, the aspect ratio of whiskers The maximum is 6.67. Excessive AlF3 causes the mullite whiskers to become thick and rod-shaped. The in-situ mullite whiskers form an interlocking structure, which enhances the flexural strength of mullite high-aluminum castables when AlF3 content When the weight is 1wt%, the flexural strength of the model reaches the maximum value of 35.92MPa, and the residual flexural strength of the sample after 5, 10, and 15 thermal shocks reaches the maximum, which are respectively 2.07 MPa, 1.95 MPa, 1.19. MPa.
Preparation of Sustained Release Mixture Aerogel Antibacterial Agent
Authors: Guo Xiaowei , Chen Nanchun , Meng Xiangjian , Wang Xiuli , Li Yuyan , Xie Qinglin
Published: November 2019

In this study, Hybrid aerogels of chitosan (CS), carboxymethyl cellulose (CMC) and Zeolite P molecular sieve (zeolite P) are successfully prepared by using Calcium chloride as the Chelator. pH-controlled drug delivery with CS/CMC/Ca2+/Zeolite P as the carrier is investigated using antibacterial agents potassium diformate (KDF), as the model drug. CS and CMC have pH sensitivity. The Zeolite Phas a large specific surface area which contributes to the enhancement of drug-loading amount. Thus, the synthesized microparticles were characterized by FTIR and XRD, and study the surface morphology of particles by SEM. The swelling and in vitro antibacterial activity of the prepared composites were studied. The particle systems developed are promising for adjusting the pH of the intestine and modulate gut microbiota in the intestinal tract with the purpose of improving piglets health.
Pinhole Effect Investigation in Electrowetting Dielectrics by Current Density Measurements
Authors: Wang Weiqiang , Yan SU
Published: November 2019

In this paper, we use current density measurement as an important diagnostic method to study the reliability of electrowetting devices. The current density distribution data is closely related to the early detection of malfunctions or failures in the devices. Here we use segmented cell technology to investigate the current density distributions in the top substrate to determine the initiation of dielectric breakdown. The current density measurements are further used to determine the signature of pinhole formation in the dielectric film. Different behavior is observed for dielectric failure under DC and AC voltages, and a sudden current change associated with vaporization of water is assumed to trigger the failure of the device.
Electrospinning Preparation and Infrared-Emissivity Properties of Zn1-xCoxO Nanofibers
Authors: Wang Xinkun , Zhao Fang , Wang Jianjiang , Ma Weining
Published: November 2019

Wurtzite-type Zn1-xCoxOnanofibers were successfully fabricated by sol-gel method combined with electrospinning technology. The as-prepared fiber samples were characterized by TGA-DSC, XRD, FTIR and SEM techniques. The infrared emissivity of the product were tested using an IR-2 infrared emissivity analyzer. The results show that wurtzite structure is formed at 600°C for 2h. These nanofibers have diameters in the range of 60-100nm. As the doping concentration increases, The infrared emissivity of the sample decreases first and then increases slowly. When x = 0.04, the lowest infrared emissivity is 0.76.This makes Zn1-xCoxO nanofibers have a good prospect in the infrared emissivity nanomaterials.
Enhancement of Microstructure Development and Current-voltage Characteristics of ZnO-Bi2O3Varistor Ceramics Sintered with Sintering aids at the Low-Temperature
Authors: Liu Wenjin , Cheng Lihong , Ai Jianping , Su Kaiyu , Li Wenkui
Published: November 2019

ZnO-Bi2O3based varistor ceramics doped with SnO2or with SnO2, B2O3and SiO2were prepared by traditional solid–state reaction method respectively. The microstructure and properties of samples sintered at a low temperature range from 910 to 950°C were studied. Results show that: by low-temperature sintering, the sintering aids can improve the sample’s density and homogeneity, and therefore the overall properties of the samples. It was found that the samples sintered at 910°C with SnO2as sintering aid possess the best performance, and the breakdown voltage is 1368 V/mm, nonlinear coefficient is 12.2, and the leakage current is less than 0.1 μA.
Synthesis of Li7La3Zr2O12 Solid Electrolyte by Solid Phase Sintering Method
Authors: Liu Guanghua , Li Tianjun , Xing Yan , Pan Wei
Published: November 2019

Li7La3Zr2O12 (LLZO) is a promising electrolyte material for all-solid-state battery due to its high ionic conductivity and good air stability with metallic lithium. In this article, Li7La3Zr2O12 electrolytes with excess lithium 4wt%, 6wt%, 8wt%, 10wt% were prepared by traditional two steps solid-phase sintering method. The influence of concentration of lithium and calcination temperature on the structure of Li7La3Zr2O12 were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) in detail. To improve the density of the sample, the granulation was applied. Scanning electron microscopy (SEM) results showed the granulation of Li7La3Zr2O12 power before pressing can significantly accelerate densification during the final high temperature, long duration sintering process.
Extraction of Potassium from Biotite by Lithium Ion Exchange and Its Electrochemical Properties
Authors: Cheng Yilin , Huang Zhiliang , Yao Donghui , Wu Changsheng
Published: November 2019

In order to solve the problem of shortage of potassium resources in China, the technology of extracting soluble potassium from insoluble potassium minerals needs to be further studied. Biotite with relatively high potassium content was used as the research object to extract soluble potassium elements from biotite by lithium ion exchange method, and the electrochemical properties of biotite were tested after potassium extraction. After 80°C hydrothermal reaction for hours, potassium and lithium ion exchanged with each other, and soluble potassium were obtained from the filtrate by filtering the reaction liquid. The efficiency of potassium extraction and the structure of mica changed after the oxidation reaction was determined by XRF and XRD, respectively. The results showed that the layered silicate structure of mica after the reaction was not destroyed, and the potassium extraction rate for 8h was up to 92.3%. The discharge capacitance was 1.32F/g, and the coulomb efficiency was 64% in 0.6C.
Oxidation Behavior of Cu Doped CrAlN Coating Deposited by Magnetron Sputtering at 800°C
Authors: Chang Weijie , Zhang Hao , Li Xiangrui , Huang Chuan , Wang Yulong , Song Lingling , Duo Shuwang
Published: November 2019

CrAlN coating with moderate Cu content was deposited on the surface of 1Cr18Ni9Ti stainless steel by DC reactive magnetron sputtering. The oxidation behavior under 800°C of the coatings was investigated emphatically in this research. The phase construction, microstructure and chemistry contents were analyzed by X-ray diffraction (XRD), field-emission electron scanning microscope (FESEM) and energy disperse spectroscopy (EDS). And the mechanical properties of the coatings were measured by microhardness tester and multi-function scratcher. As a comparison, the properties of CrAlN coating were also analyzed in the article. The results showed that the microstructure of CrAlCuN coating became smother and denser with a phase structure of CrN and Cu. With Cu doped in the CrAlN coating, the more excellent hardness which enhanced to 48.37 GPa was obtained. While the bonding strength of the coating was decreased because of the advanced microhardness usually released more internal stress. Both of the coatings were not complete failure and CrN diffraction peak was also tested. The oxidation rate of weight gain had significantly decreased with Cu doped, which improved the resistance of high temperature oxidation to a certain extent.
Service Time Performance Analysis of Improved Automated Restaurant by Layout Reconfiguration and Conveyor System
Authors: Chin W J , Lim M , Yong J C E , Al-Talib AAM , Chaw K H
Published: November 2019

Achieving effective service time in restaurants hinges on implementing and integrating innovation in design and technology. A combination of restaurant layout configuration and conveyor belt system integration is proposed to enhance the turnaround service time performance. Emphasis on the layout reconfiguration with optimized dining capacity and conveyor system for semi-automated function are applied to existing restaurants by heuristic method. Then operation is simulated by agent-based approach in Anylogic simulator. Results yielded an improved in the total turnaround service time by 2.75% to 5%, which correspond to an approximate 78% reduction on a food-to-table service time. The enhanced performance shows the effectiveness of reconfigured layout to service more customers without compromising delivery time. While conveyor belt mechanism provides the greatest food delivery time and manpower reduction, with a considerable payback period of 6 months. The findings and modelling will aid the implementation of semi-automated restaurant as a stepping stone to one fully automated.
Design of Storage and Monitoring System for Medical Dangerous Chemicals Based on Wireless Sensor Network
Authors: Zhang Tao , Xu Ren-Ren , Zhang Ya-Wei , Meng De-Qiang
Published: November 2019

Medical hazardous chemicals storage system is a special storage system. Its management basically relies on getting rid of a lot of manpower and increasing the safety and reliability of management. Using information management is a necessary way to improve storage efficiency, reduce storage cost and improve storage security. This design adopts wireless sensor network technology according to the characteristics of storage system of medical dangerous chemicals (Wireless Sensor Networks, WSNs). The wireless sensor network node design scheme is proposed. Based on IEEE802.15.4/ZigBee protocol, the wireless sensor network node is designed and implemented by PIC18F4620 single chip microcomputer and wireless radio frequency chip CC2420. Realize low cost to improve the security and real-time of monitoring, realize information sharing and network remote monitoring.
Planning Path Strategy and Simulation of Infusion Service Robot Based on Ant Colony Algorithm
Authors: Zhang Tao , Meng De-Qiang , Zhao Su-Dong
Published: November 2019

The infusion service robot was taken as the research object, and the algorithm of path planning for infusion service robot was simulated by the sensor network system in this experiment. The ant colony algorithm was selected based on the sensor network node optimization deployment of the mobile service robot. Based on sensor network for hospital environmental information collection, combined with sensor network node information and RSSI algorithm based on MATLAB to achieve positioning, and then complete the simulation study of infusion service robot navigation. The ant colony algorithm was verified as the basic method and feasibility of applying the path strategy of the robot platform. During the testing process, some conditions and algorithms were simplified to avoid the complexity of the problem.
Calculation of Parameters of the Cryogenic Rotor-Blade Engine for the Drive of the Refrigeration Unit for Truck
Authors: Uglanov D , Tereshchenko O , Zaika S , Neverov I , Panshin R
Published: November 2019

Cars with internal combustion engines using hydrocarbon fuels occupy the main market share. The cost of these products is increasing, and this negatively affects the prosperity of the population and the cost of freight transportation. The growth in energy consumption and the rapid growth of cars deplete non-renewable natural oil and gas resources, leading to intense combustion of atmospheric oxygen.

One of the promising types of environmentally friendly engine is a cryogenic fuel engine. Such engines have higher energy performance and lower cost in comparison with electric vehicles, and their operating costs are comparable with traditional cars, taking into account the ecological aspect.

The study presents the development of methods for calculating the rotor-blade engine and its design. Since refrigeration plants consume 3% of the internal combustion engine power, it is advisable to replace them with autonomous units using a cryogenic working fluid, thereby reducing emissions of harmful substances into the atmosphere.
Automobile Connecting Rod Forging Optimization Based on DEFORM and Orthogonal Experiment
Authors: Hong-wei XU , Yan-bo JING , Xiao-ming QI , Shou-dong LI , Dou-wei LIU
Published: November 2019

Taking blank temperature, mould temperature and friction coefficient as test factors, the orthogonal experiment of three factors and three levels of automobile connecting rod forging was designed. Using Deform-3d, the forging experiment under different factors is simulated, and the forging results under different technological parameters were obtained. The process parameters of connecting rod forging are optimized by using the comprehensive measurement method and taking deformation uniformity and maximum forming load as indexes. The results show that the optimized process parameters can reduce the forming load and improve the deformation uniformity.
Design of Magnetic Circuit and Finite Element Analysis of Stepped Ferrofluid Seal with Small Sealing Gap
Authors: Zhang Ruibo , Yang Xiaolong , Wang Guohong
Published: November 2019

For the sake of study the pressure capability of ferrofluid seals with small sealing gap, a diverging stepped ferrofluid structure with small sealing gap was designed according to the theory of stepped ferrofluid and magnetic path design, and the length and cross-sectional area of the permanent magnet (NeFeB) are obtained. On the basis of these parameters, the ferrofluid distribution of seal gap is calculated by using the magnetic ferrofluid element method, and the pressure capability is obtained, then the reliability of the magnetic path design is obtained according to the capability of withstand voltage. There are some findings as following after analysis and comparison. It is the magnetic flux leakage at the junction of the pole boot and NeFeB that cause pressure capability calculated by the magnetic path method is lower than that calculated by the finite element method.
Design Method of Engine Room Equipment Layout Based on Improved Fuzzy Comprehensive Evaluation
Authors: Zhigang Huang , Xinyu Zhang , Jingyu Liu
Published: November 2019

Engine room is the place where marine power equipments, pipelines and other equipments are arranged centrally. In order to optimize the design process of engine room equipment layout, this paper proposes a method for the optimization design of engine room layout baesd on improved fuzzy comprehensive evaluation. By constructing the personnel activity space model and equipment space model, formulating the engine room environment constraint conditions dominated by personnel experience factors and obtaining the feasible scheme of engine room equipment layout. By designing the evaluation model of equipment layout plan in the engine room, formulating the evaluation method dominated by fuzzy comprehensive evaluation algorithm and obtaining the optimal layout scheme. Based on fuzzy comprehensive evaluation method, the improved method directly retains the influence of the design experience factors of personnel, which can make engine room equipment layout and pipelines more in line with engineering requirements, as well as provide better equipment accessibility and personnel accessibility.
Structural Optimization for Stiffness and Stochastic Fatigue Life Improvement of a Sport Utility Vehicle Chassis
Authors: Wang Wenlin , Huang Bao , Du Jianming , Cheng Siyuan
Published: November 2019

To further improve the structural dynamic performance of the Land-Wind X-6 chassis, structural optimization was performed: An X-shape cross member with high stiffness is added to the chassis, in addition, the cross member connecting the two torsion bar attachments is also strengthened. Extensive Finite Element Analysis (FEA) demonstrates that the inadequate torsion stiffness has been greatly increased by 102.6% after optimization, and the adequate bending stiffness has also been slightly improved by 3.8%, in addition, the level of local stresses on the chassis has been considerably declined; After optimization, the fatigue life coefficient when the vehicle is running on A-class concrete road at a speed of 110 km/h has been improved by about 40.36%, and that when the vehicle is running on D-class macadam road at a speed of 60 km/h has been improved by about 33.43%. Followed industrial implementation, field test result and product feedback information verify that the structural optimization performed in this study is effective and significant.
Effect of Dynamic Balance Parameters on Vibration of Vertical and Horizontal Rotor System
Authors: Yan Zhong , Ji Wu , Kejin Ding
Published: November 2019

In this paper, a rotor test device for vertical-horizontal conversion is designed. The effects of unbalanced mass, dynamic balance position and other dynamic balance parameters on the vibration response of the rotor system are experimentally analyzed, and the difference of the vibration response of the rotor system between vertical and horizontal States is compared. The test results show that the vibration of the bearing base foot will increase after the dynamic balancing rotor is installed in the vertical shafting in the horizontal state; in order to ensure the dynamic balancing accuracy, the dynamic balancing of the vertical rotor system should be carried out on the vertical system as far as possible, and the aggravation should be carried out far away from the driving end. The research results in this paper can provide necessary support for the determination of dynamic balancing process and the study of dynamic characteristics of vertical rotors.
Modeling and Simulation Study of Intake System Characteristics of Wankel Engine for UAV
Authors: Xiaqing LIU , Minxiang WEI , Rui LIU
Published: November 2019

Starting from the actual working process of Wankel engine, the intake system model of Wankel engine is constructed based on the mean value engine model. The parameters to be determined in the model are identified by the least-square method based on the engine test data. According to the nonlinear characteristics of the intake system, the structure of the model is improved by introducing the speed correction term, and the problem that the error of original throttle air mass flow model is larger under the larger throttle opening is solved. The results of simulation and steady-state test show that the maximum relative error between simulation and experimental values of throttle air mass flow is less than +3% and that between simulation and experiment values of intake pressure is less than +2%.The parameter identification and structure of the model have high precision, which can calculate the basic air intake flow of Wankel engine accurately and shorten the development cycle of the electric control system of Wankel engine.
Transformation of Arctic ecosystems under impact of open-pit extraction of mineral resources
Authors: Selyanina S B , Ponomareva T I , Mikhailova G V , Churakova E Yu , Zubov I N , Yarygina O N
Published: November 2019

The article considers the influence of open-pit mining of diamonds on the state of Arctic ecosystems outside of the zone of the direct impact of the enterprise. To assess changes in natural complexes, a retrospective analysis was carried out on the basis of the data from social surveys of the local population using adapted methodological approaches and comparing descriptions of the biodiversity of aquatic macrophytes made in 1969-1970 and 2018. The comprehensive studies of peat soils and the laboratory modeling of the flow of the saponite into the watercourse were carried out, in order to understand the possible ways of the impact of diamond mining on natural complexes. The shallowing of the river, the change in the nature of soils in the lower reaches of the river, the crowding out a number of native species of aquatic plants by invasive macrophytes were educed. It is shown that saponite interacts with components of bog ecosystems, changes its physicochemical properties and forms intermolecular associates with dissolved organic matter. This contributes to the transport of mineral particles over long distances, to its accumulation in bottom sediments, and to the prolonged desorption, which creates favorable conditions for the introduction of invasive species.
Comparative assessment of drag reduction efficiencies of polymer solutions and surfactants at low temperatures
Authors: Kashlach E S , Berezina E M , Smirnova A S , Berezina I A , Manzhai V N , Fufaeva M S
Published: November 2019

The antiturbulent efficiency of solutions of high molecular weight polymers and that of micellar systems of surfactants are compared. The effect of the structural organization of polymer solutions and colloidal systems on their antiturbulent efficiency is shown. Hydrodynamic and physicochemical approaches are used to interpret the experimental results. It is shown that the use of polymers as drag reducing agents in main oil pipelines is more preferable at low liquid temperatures in northern latitudes (the Arctic).
Structure and properties of invar alloys for MIM technologies
Authors: Kulkov S N , Abdulmenova E V , Shadrin V S , Leonov A A , Levkov R V
Published: November 2019

The paper studied Fe-Ni alloys obtained by sintering from mixtures of powders. Powders with 30-40 wt. Ni were mixed with paraffin and wax binder and then pressed and sintered at 1300 °C during 1 hour. It has been shown that the face centered cubic lattice (γ-phase) and body centered cubic lattice (α-phase) are formed after sintering of powders mixture. The content of the α-phase decreases from 37 % to 2 % with increase of Ni concentration from 30 to 35 wt. % Ni in powders mixture. The average grain size of the γ-phase decreases from 26.5±12.3 μm to 18.3±9.1 μm, and porosity of samples increases from 13±1.4 % to 18.4±1.1 %.The lattice parameter of the γ-phase increases from 3.5849·10−10 m to 3.597·10−10 m and it corresponds to well-known invar alloys. The maximum value of the microhardness of sintered samples is 1.04±0.07 GPa. Thus, alloys obtained by sintering of Fe and Ni powder mixtures has an invar properties typical of cast alloys.
High-Temperature Laminated Ceramic Material Hfc-ZrB2-SiC-ZrO2 for the Development of the Arctic and Siberia
Authors: Burlachenko A G , Mirovoy Yu A , Buyakova S P , Dedova E S , Kulkov S N
Published: November 2019

Ultra-high-temperature ceramics based on zirconium diboride and silicon and hafnium carbides are presented as composites with ceramic matrix and oxidation-resistant surface. Relatively low density, high strength at extreme temperatures and operability at oxidative environment with temperature up to 2000°C make these materials useful for aerospace construction and power engineering. HfC-ZrB2-SiC-ZrO2 systems are presented, structural analysis and the results of temperature tests in high-enthalpy gas are provided. It was demonstrated that high resistance of HfC-ZrB2-SiC-ZrO2 system to high-temperature corrosion is achieved owing to formation of protective oxide layer with variable composition. A key area for the use of the material in the Arctic is the organization of heat-shielding structures in the oil and gas industry.
The influence of stress states on the martensitic transformation in Y-TZP ceramic
Authors: Sablina T.Yu. , Sevostyanova I.N. , Bayanov A.N. , Kulkov S.N.
Published: November 2019

It has been studied the influence of the type of stress state arising during different types of loading - for axial compression, diametral compression (Brazilian test) and three-point bending of Y-TZP ceramics with different grain sizes. It was shown that with increasing grain size of ceramics there is an increase in strength properties. The maximum values of all strength characteristics are fixed for ceramics with a grain size of 1.55 microns. It was found that on the fracture surfaces the formation of a monoclinic phase caused by the tetragonal–monoclinic transformation under the influence of applied stresses after axial compression test, Brazilian test and three-point bending test. As the average grain size increases, the content of the monoclinic phase increases after all types of mechanical tests. For ceramics with the average grain size of 0.53 µm, regardless of the type of loading, the content of the monoclinic phase on the fracture surface was approximately 5-7%. For ceramics with a maximum grain size of 1.55 microns after axial and diametrical compression tests, the content of the transformation phase increased to 27 % and after bending tests up to 39 %. The increased content of the monoclinic phase on the fracture surface after bending tests, in comparison with the axial and diametrical compression tests, is due to a complex stress-strain state, when during deformation areas with tensile and compressive stresses are formed on the fracture surface.
Algorithms and models of multirobot systems and their implementation in ROS
Authors: Shikhman M V , Shidlovskiy S V
Published: November 2019

Conducting research in the Arctic takes place in extreme conditions. In these conditions, it’s effective to use multirobot systems that can function for days under any weather conditions. The article discusses the basic principles of multirobot control systems. Mathematical models for the formation of control actions of multirobot are obtained. The basic methods for modeling multi-robot systems in ROS are described.
Field theory of monochromatic optical beams: I. Classical fields
Authors: Aiello Andrea
Published: November 2019

We study monochromatic, scalar solutions of the Helmholtz and paraxial wave equations (PWEs) from a field-theoretic point of view. We introduce appropriate time-independent Lagrangian densities for which the Euler–Lagrange equations reproduces either Helmholtz and PWEs with the z-coordinate, associated with the main direction of propagation of the fields, playing the same role of time in standard Lagrangian theory. For both Helmholtz and paraxial scalar fields, we calculate the canonical energy-momentum tensor and determine the continuity equations relating ‘energy’ and ‘momentum’ of the fields. Eventually, the reduction of the Helmholtz wave equation to a useful first-order Dirac form, is presented. This work sheds some light on the intriguing and not so acknowledged connections between angular spectrum representation of optical wavefields, cosmological models and physics of black holes.
The Association between Reward Sensitivity and Activity Engagement: the Influence of Delay Discounting and Anhedonia
Authors: Veldhoven Deni Tressova-van , Roozen Hendrik , Vingerhoets Ad
Published: November 2019

Aim

Reward sensitivity affects individuals’ motivation to engage in goal-directed behavior. Other concepts, critical for reward appraisal, that potentially influence activity participation encompass delay discounting and anhedonia. The aim of this study was to test the hypothesis that anhedonia and delay discounting influence the relationship between reward sensitivity and activity engagement.

Methods

In total, 37 inpatient patients with an alcohol use disorder (AUD) and 37 matched healthy controls completed the behavioral activation system scale (BAS scale), the Pleasant Activities List (PAL), the Snaith–Hamilton Pleasure Scale (SHAPS) and the Delay Discounting Task (DDT).

Results

Patients differed from controls on SHAPS, DDT-k, PAL substance-related activities (SRA), but not BAS and PAL non-substance-related activities (non-SRA). Correlational analyses revealed a strong correlation between BAS and PAL non-SRA in both patients (r = 0.53) and controls (r = 0.47), but also with PAL-SRA in patients (r = 0.40), although not controls (r = 0.09). BAS was negatively correlated with SHAPS in both groups and with DDT in controls. SHAPS was negatively linked to PAL non-SRA in both groups. The BAS-PAL non-SRA relationship was influenced by discount rates in controls.

Conclusion

A strong link exists between reward sensitivity and engagement in non-SRA in both groups. Delay discounting affects the reward sensitivity and non-SRA association in healthy controls, while anhedonia did not impact the association between reward sensitivity and engagement in (non-)SRA in both conditions.
Hepatitis C Virus Cure Rates Are Reduced in Patients With Active but Not Inactive Hepatocellular Carcinoma: A Practice Implication
Authors: Ogawa Eiichi , Toyoda Hidenori , Iio Etsuko , Jun Dae Won , Huang Chung-Feng , Enomoto Masaru , Hsu Yao-Chun , Haga Hiroaki , Iwane Shinji , Wong Grace , Lee Dong Hyun , Tada Toshifumi , Liu Chen-Hua , Chuang Wan-Long , Hayashi Jun , Cheung Ramsey , Yasuda Satoshi , Tseng Cheng-Hao , Takahashi Hirokazu , Tran Sally , Yeo Yee Hui , Henry Linda , Barnett Scott D , Nomura Hideyuki , Nakamuta Makoto , Dai Chia-Yen , Huang Jee-Fu , Yang Hwai-I , Lee Mei-Hsuan , Jun Mi Jung , Kao Jia-Horng , Eguchi Yuichiro , Ueno Yoshiyuki , Tamori Akihiro , Furusyo Norihiro , Yu Ming-Lung , Tanaka Yasuhito , Nguyen Mindie H ,   Real-World Evidence from the Asia Liver Consortium Investigators
Published: November 2019

Background

Cure rates of hepatitis C virus (HCV) treatment with direct-acting antivirals (DAAs) for patients with active and inactive hepatocellular carcinoma (HCC) may differ, but well-controlled studies are limited. We aimed to evaluate DAA outcomes in a large East Asian HCV/HCC population compared with HCV/non-HCC patients.

Methods

Using data from the Real-World Evidence from the Asia Liver Consortium (REAL-C) registry (Hong Kong, Japan, South Korea, and Taiwan), we used propensity score matching (PSM) to match HCC and non-HCC (1:1) groups for age, sex, cirrhosis, prior treatment, HCV genotype, treatment regimen, baseline platelet count, HCV RNA, total bilirubin, alanine aminotransferase, and albumin levels to evaluate DAA treatment outcomes in a large population of HCV/HCC compared with HCV/non-HCC patients.

Results

We included 6081 patients (HCC, n = 465; non-HCC, n = 5 616) treated with interferon-free DAAs. PSM of the entire study population yielded 436 matched pairs with similar baseline characteristics. There was no statistically significant difference in the overall SVR rate of HCC (92.7%) and non-HCC (95.0%) groups. Rates of treatment discontinuation, adverse effects, and death were also similar between HCC and non-HCC groups. Among patients with HCC, those with active HCC had a lower SVR than inactive HCC cases (85.5% vs 93.7%; P = .03). On multivariable analysis, active HCC, but not inactive HCC, was significantly associated with lower SVR (OR, 0.28; P = .01) when compared with non-HCC.

Conclusions

Active HCC but not inactive HCC was independently associated with lower SVR compared with non-HCC patients undergoing DAA therapy, although cure rate was still relatively high (85%) in active HCC patients.
Net ultrafiltration rate and its impact on mortality in patients with acute kidney injury receiving continuous renal replacement therapy
Authors: Tehranian Shahrzad , Shawwa Khaled , Kashani Kianoush B
Published: November 2019

Background

Fluid overload, a critical consequence of acute kidney injury (AKI), is associated with worse outcomes. The optimal fluid removal rate per day during continuous renal replacement therapy (CRRT) is unknown. The purpose of this study is to evaluate the impact of the ultrafiltration rate on mortality in critically ill patients with AKI receiving CRRT.

Methods

This was a retrospective cohort study where we reviewed 1398 patients with AKI who received CRRT between December 2006 and November 2015 at the Mayo Clinic, Rochester, MN, USA. The net ultrafiltration rate (UFNET) was categorized into low- and high-intensity groups (<35 and ≥35 mL/kg/day, respectively). The impact of different UFNET intensities on 30-day mortality was assessed using logistic regression after adjusting for age, sex, body mass index, fluid balance from intensive care unit (ICU) admission to CRRT initiation, Acute Physiologic Assessment and Chronic Health Evaluation III and sequential organ failure assessment scores, baseline serum creatinine, ICU day at CRRT initiation, Charlson comorbidity index, CRRT duration and need of mechanical ventilation.

Results

The mean ± SD age was 62 ± 15 years, and 827 (59%) were male. There were 696 patients (49.7%) in the low- and 702 (50.2%) in the high-intensity group. Thirty-day mortality was 755 (54%). There were 420 (60%) deaths in the low-, and 335 (48%) in the high-intensity group (P < 0.001). UFNET ≥35 mL/kg/day remained independently associated with lower 30-day mortality (adjusted odds ratio = 0.47, 95% confidence interval 0.37–0.59; P < 0.001) compared with <35 mL/kg/day.

Conclusions

More intensive fluid removal, UFNET ≥35 mL/kg/day, among AKI patients receiving CRRT is associated with lower mortality. Future prospective studies are required to confirm this finding.
Decentralisation of agri-environmental policy design
Authors: Bareille François , Zavalloni Matteo
Published: November 2019

We theoretically examine the gains of the decentralisation of agri-environmental policy design. We consider a model with homogeneous regions and joint production of local and global public goods from agriculture. Assuming that governments are characterised by different agency costs and knowledge of the PG values, we evaluate whether decentralisation is a suitable strategy to improve the efficiency of agri-environmental payments. We find that partial decentralisation always improves the welfare. We apply our theoretical model to the case of abandoned wetlands in Brittany. We find that national governments are the most suitable to design agri-environmental policies. Our results contribute to reflections on future Common Agricultural Policy.
Is the End of Educational Hypergamy the End of Status Hypergamy? Evidence from Sweden
Authors: Chudnovskaya Margarita , Kashyap Ridhi
Published: November 2019

The reversal of the gender gap in higher education has been a major social transformation: women now outnumber men in higher education in nearly all OECD countries. Patterns of assortative mating have also changed as highly educated women increasingly form relationships with men who have less education (hypogamous unions). In this article, we draw on rich register data from Sweden to ask whether the emergence of hypogamous unions signals the emergence of a new female status dominance in unions. We also consider how the status distribution in these unions compares to homogamous (both highly educated) or hypergamous (he highly educated) unions. We use Swedish register data and study couples who have their first child together. We refer to a multi-dimensional view of status and use indicators of social class background, income, and occupational prestige. We find that in hypogamous unions, women tend to have a higher social class background and occupational prestige, but lower income than their partners. The income gap between partners is not simply a consequence of the gender wage gap, but driven by selection into different union types. Men and women who form hypogamous unions are negatively selected in terms of their income.
Comparison of the gut microbiota of Rana amurensis and Rana dybowskii under natural winter fasting conditions
Authors: Tong Qing , Du Xiao-peng , Hu Zong-fu , Cui Li-yong , Bie Jia , Zhang Qian-zhen , Xiao Jian-hua , Lin Yu , Wang Hong-bin
Published: November 2019

Rana amurensis and R. dybowskii occupy similar habitats. As temperatures decrease with the onset of winter, both species migrate to ponds for hibernation. Our goal was to determine whether different species possess different intestinal microbiota under natural winter fasting conditions. We used high-throughput Illumina sequencing of 16S rRNA gene sequences to analyse the diversity of intestinal microbes in the two species. The dominant gut bacterial phyla in both species were Bacteroidetes, Proteobacteria and Firmicutes. Linear discriminant analysis (LDA) effect size revealed significant enrichment of Proteobacteria in R. amurensis and Firmicutes in R. dybowskii. There were significant differences in the gut microbiota composition between the species. The core operational taxonomic unit numbers in R. amurensis and R. dybowskii shared by the two species were 106, 100 and 36. This study indicates that the intestinal bacterial communities of the two frog species are clearly different. Phylum-level analysis showed that R. amurensis was more abundant in Proteobacteria and Verrucomicrobia than R. dybowskii was This is the first study of the composition and diversity of the gut microbiota of these two species, providing important insights for future research on the gut microbiota and the role of these bacterial communities in frogs.
Social Isolation and Memory Decline in Later-life
Authors: Read Sanna , Comas-Herrera Adelina , Grundy Emily
Published: November 2019

Objectives

To investigate associations between level and changes in social isolation and in memory in older men and women.

Methods

The sample included 6,123 women and 5,110 men aged 50+ from the English Longitudinal Study of Aging (ELSA). Extended latent change score models from six measurement occasions every 2 years from 2002 were used to investigate associations between social isolation and memory. Models were adjusted for age, socioeconomic position, and health.

Results

Social isolation increased and memory decreased over time. Among men an initially high level of social isolation was associated with a somewhat greater decrease in memory. Among women a greater increase in social isolation predicted a greater decrease in memory and a larger change in social isolation was associated with further larger changes in isolation, although when social isolation reached a higher level it subsequently decreased.

Conclusions

Results suggest that the association between social isolation and memory decline arises because social isolation is associated with increased memory decline rather than poor memory leading to increases in social isolation. Men with high levels of social isolation and women with accumulated social isolation over time are especially affected as these patterns of isolation were associated with more profound memory decline.