bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of turbulence intermittency in linear magnetized plasma
Authors: Zhang Boyu , Inagaki Shigeru , Hasamada Kazunobu , Yamasaki Kotaro , Kin Fumiyoshi , Nagashima Yoshihiko , Yamada Takuma , Fujisawa Akihide
Published: September 2019

The intermittent behavior of a quasi-coherent density fluctuation is observed in a laboratory plasma. The quasi-coherent fluctuation is localized but intermittent events are observed in the whole region of plasma. Conditional averaging shows the intermittent events propagate from the central region of the magnetized plasma column to the peripheral region. Auto-correlation function of fluctuations and Hurst analysis reveal the intermittency is highly auto-correlated and the Hurst parameter reaches to 0.8, indicating the existence of self-similar behavior and long-range time correlation, and self-organized criticality dynamics might be the mechanism. Cross-bicoherence between different radii shows the nonlinear coupling between the quasi-coherent fluctuation and ambient turbulence, which will contribute to the generation of intermittency of turbulence.
Phonon quarters-wave loss
Authors: Xiong Guohuan , Yu Zhizhou , Wang Jian-Sheng , Zhang Lifa
Published: September 2019

There has been a growing interest in the phase of phonon, due to the theoretical prediction (Phys. Rev. Lett. 115.11 (2015)) and the experimental observation (Science 359.6379 (2018)) of chiral phonons, which have different phases in different components. While half-wave loss is a well-known concept in optics, in this work, a series of plateaus of quarters-wave loss are first found for the reflected phonon across an interface by using an atomic junction model. These plateaus can be understood by the S-matrix in the system with time-reversal symmetry. If a phonon wave propagates from a low acoustic-impedance material (or a low cutoff frequency material) to a higher one in the long-wave limit (or in the high frequency limit), a half-wave loss takes place for the reflected phonon; however, the plateau of half-wave loss for reflected phonon occurs in the whole frequency domain if phonon transfers to a material with a larger spring constant. Besides the half-wave loss, we also observe plateaus of quarter-wave (three-quarters-wave) loss in long wave limit when the two leads with identical acoustic impedance are coupled by a weak (strong) coupling in comparison with the optimum thermal coupling. The quarters-wave loss for phonons can be applied to chiral phonon manipulation and other phononics devices.
Time-resolved CCD photometry and time-series analysis of the RR Lyrae type star RR Gem
Authors: Gohil Virabhadrasinh A. , Bhatnagar Sachchidanand Prakash
Published: September 2019

We present the results of a time-resolved photometric and time-series analysis of an RR Lyrae type star RR Gem. The main results are as follows: we found RR Gem’s pulsation period, 0.39689 d, and its V and I mean magnitudes, 11.277 (V) and 11.063 (I) mag respectively. We confirm its variability type as RRab/BL because it manifests the Blazhko effect, and it also exhibits asymmetric light curves (steep ascending branches), periods from 0.3 to 1.0 d and amplitudes from 0.3 to 2 mag in V. They are fundamental mode pulsators.
Optimal site selection for an optical-astronomical observatory in Pakistan using Multicriteria Decision Analysis
Authors: Daniyal  , Kazmi Syed Jamil Hassan
Published: September 2019

An astronomical observatory is the core component of any astronomical research facility that connects astronomers with their lab: the Cosmos. The research quality of an astronomical facility is rooted in the precision of data, collected by its observatory. For optimal performance, an observatory is sited while considering certain astronomical, environmental, geological and social parameters. This study aims to identify the potential sites in Pakistan for locating an optical-astronomical observatory using the Multicriteria Decision Analysis (MCDA) technique. The study uses the Analytic Hierarchy Process (AHP) for deriving the influence weights of nine evaluation criteria: Photometric Night Fraction; Night-time Sky Brightness; Sky Transparency; Aerosol Concentration; Altitude; Terrain Slope; Accessibility; Seismic Vulnerability; and Landuse/Land Cover. On the basis of experts’ opinions and previous studies, the evaluation criteria have been ordered in two possible preference sequences for identifying their influence weights with respect to each other for taking part in MCDA. Consequently, the process of MCDA identified certain areas with respect to each preference sequence, whereas some areas were found to be suitable according to both preference sequences. The study synchronizes the required eclectic data into an evaluationmatrix that augments the process of astronomical site selection. In the future, this study will be useful for astronomical societies and for furthering astronomical research in the country.
Systematic investigation of mid-term periodicity of the solar full-disk magnetic fields
Authors: Xiang Nan-Bin
Published: September 2019

The Magnetic Plage Strength Index (MPSI) and theMountWilson Sunspot Index (MWSI), which have been measured at Mount Wilson Observatory (MWO) since the 1970s and which indicate weak and strong magnetic field activity on the solar full disk, respectively, are used to systematically investigate midterm periodicities in the solar full-disk magnetic fields. Multitudinousmid-term periodicities are detected in MPSI and MWSI on timescales of 0.3 to 4.5 yr, and these periodicities are found to fluctuate around several typical periodicities within a small amplitude in different solar cycles or phases. The periodicity of 3.44 yr is found in MPSI, and the periodicities of 3.85 and 3.00 yr are detected in MWSI. Our analysis indicates that they reflect the true oscillating signals of solar magnetic field activity. The typical periodicities are 2.8, 2.3 and 1.8 yr in MPSI and MWSI, and possible mechanisms for these periodicities are discussed. A 1.3 yr periodicity is only detected in MPSI, and should be related to meridional flows on the solar surface. The typical annual periodicity of MPSI and MWSI is 1.07 yr, which is not derived from the annual variation of Earth’s heliolatitude. Several periodicities shorter than 1 yr found in MPSI and MWSI are considered to be Rieger-type periodicities.
Image Processing of Case Study of Solar Radio Burst Type III and Type IV Burst Using Sunpy
Authors: Hamidi Z. S. , Ramli N. , Shariff N. N. M.
Published: September 2019

Solar radio burst at low-frequency lies in the fact that they originate in the same layers of the solar atmosphere in which geo-effective disturbance probably originate Type III bursts have consistently the fastest drift rates of bursts at metric wavelengths and was created by an electron beam through plasma emission. Meanwhile, type IV burst is broadband quasi-continuum features associated with the decay phase of solar flares. A geomagnetic storm is a major disturbance of Earth’s magnetosphere that occurs when there is a very efficient exchange of energy from the solar wind into the space environment surrounding Earth. The aim of this study is to find out whether type III bursts preserved energy to solar bursts type IV thus led to the formation of geomagnetic storm. The solar radio burst type III and IV were observed by CALLISTO Spectrometer. CALLISTO is an acronym from Compound Astronomical Low cost Low frequency Instrument for Spectroscopy and Transportable Observatory. The Sunpy by Python was used to analyze the spectrogram image by eliminate the unwanted signal or noise in the image which is in the presence of noise, the spectrum gives inaccurate reading of frequency and time. Although the study did not show much correlation between bursts type IV and type III in producing these storms, there are several possible explanations from this result. It may be the case that solar events such as solar flare, CMEs and active region ejected from the solar disc is not heading towards Earth and the energy has eventually disperses into the interplanetary medium.
Molecular Engineering of Quinodimethane-based Dyes with Different Anchor Groups for Dye Sensitized Solar Cells (DSSCs)
Authors: Tang Jianhao , Gong Yun
Published: September 2019

This paper mainly works on changing different anchoring groups of quinodimethane-based dyes, which represent a twisting phenyl ring during the excitation process, for dye-sensitized solar cells (DSSCs). Five different groups, (1) cyanoacrylic acid (-CHC(CN)COOH), (2) carboxylic acid (-COOH), (3) pyridine (-C5H5N), (4) sulfonic acid (-SO3H), (5) phosphoric acid (-PO3H2), were adopted as anchors on the quinodimethane moieties forming dyes 1-5, to further explore their effects on optoelectronic properties via molecular engineering methods. Density functional theory (DFT) and time-dependent DFT (TD-DFT) were used to calculate their electronic structures and electro-optical properties. Computational results show that all dyes show suitable molecular orbital energy levels between the conductive band of TiO2 and the potentials I-/I3- redox couple so that all of 1-5 can be potential candidates for DSSCs application. Also, TDDFT results exhibit that dye 1 has the widest absorption band in UV-visible region, with the first excitation energies of 2.782 eV, while other dyes show similar first excitation energies about 0.2 eV higher than that of dye 1. In particular, dye 3 with pyridine as anchor group shows a very excellent charge transfer properties from the highest occupied molecular orbitals (HOMO) to the lowest unoccupied molecular orbitals (LUMO), with the highest HOMO level of -5.16 eV, which offers a strong driving force for dye regeneration, and a LUMO level of -2.36 eV, which enables excited electrons successfully to be injected in to titania film. Also, this pyridine anchor group offers a larger π conjugation, which may improve the ability of electron injecting and further strengthen the photovoltaic performance in DSSCs.
Experimental research of human evacuation in the case of a fire drill
Authors: Grigoraș Z C , Ibănescu M
Published: September 2019

The main purpose of this study is to analyze the human evacuation in the case of a fire drill by two different means: experimental research - “real fire drill” and numerical simulation - “virtual fire drill”.

The analyzed building can house a large number of people and its inner atrium can facilitate the spread of smoke and hot gases in the case of a real fire.

The evacuation drill was performed with about 50 students, located at the 2nd floor of the building, in two amphitheaters. They could evacuate themselves through two closed staircases to the ground floor of the building and then outside, through two exit doors.

The second purpose of this study is to establish, for the given case, if the used computer software can simulate the crowd movement and compute the travel times in accordance with the experimental research.

Another important subject is whether the computer software FDS+Evac - based on the CFD (Computational Fluid Dynamics) to simulate the crowd movement - can correctly identify the shortest escape path because one of the staircases, with its correspondent ground floor exit, is closer to the two analyzed amphitheaters.

Following the numerical analysis, it was concluded that for the considered scenario, the differences between the “real fire drill” and the “virtual fire drill” are acceptable from an engineering point of view.

FDS+Evac can simulate with high degree of credibility human movement in case of a fire drill.
Green roof influence over the characteristics of the linear thermal bridges
Authors: Baciu I-R , Isopescu D N , Taranu N , Maxineasa S G
Published: September 2019

Urban heat island (UHI) significantly affects the thermal-energy performance of the buildings. Moreover, urban materials absorb solar and infrared radiation, heat accumulation is dispersed in the atmosphere, a fact which increases air temperature. In this context, green roofs are the most suitable solution to resolve these vital issues. The expanding benefits of a green roof, such as energy saving, thermal insulation, and mitigating heat island effect emphasize the key role of this structure in overall thermal performance of buildings and microclimate conditions of indoor spaces. The main objective of the study is to analyse the influence of extensive green roof on the heat flow, in the thermal bridges developed structurally in buildings where they might replace the classical terrace roof. The influence is analysed through the comparison of the thermal impact of a classical terrace roof and that of an extensive green roof, through thermal characteristics of their components. The first part of the paper presents the structures of each type of roof and their thermic characteristics established and evaluated according to the normative regulation in force. In this context, the classical terrace roof and extensive green roof are examined from a thermic point of view, analysing the parameters of the types of thermal bridges usually met, in order to establish if the extensive green roof might have an influence on the overall heat flow. In conclusion, the unpredictable results obtained for the analysed thermal parameters let conclude that the extensive green roof solution presents a favourable environmental impact, promoting a “beautiful” added value to a building, in terms of both sustainability and aesthetics.
Seismic vulnerability of historical orthodox churches in Romania: numerical modelling and retrofit solutions
Authors: Bârnaure M , Coman M , Marcu D
Published: September 2019

Historical orthodox churches in Romania are generally masonry structures, built without a clear understanding of earthquake demands. Past earthquakes have shown specific damage patterns for these buildings: damages in domes and bell towers, damages of the church nave (particularly a general longitudinal dislocation), damages of the infrastructure. As some of the existing buildings have high architectural or historical value, their structural strengthening is important. Typical failure mechanisms for churches under earthquake loads are identified. Based on these mechanisms, the methods for assessing the seismic vulnerability of existing churches are discussed. A historical listed church is considered as case study. The considered numerical model is presented. Qualitative and quantitative results obtained from the numerical model for the un-retrofitted building are analysed. A retrofit solution is proposed. Comparisons are made between the expected structural behaviour of the church in its present state and after structural strengthening. Conclusions are drawn regarding the seismic vulnerability of this type of buildings.
Parametric FEM analysis of steel beam-to-column connection with extended end-plate and diagonal stiffeners
Authors: Stașcov M , Venghiac V M
Published: September 2019

Connection behaviour is the most important factor in the steel structures behaviour subjected to cyclic actions. To avoid formation of plastic hinges in the column, it is stiffened with additional diagonal stiffeners. This paper presents an FEM analysis of extended end-plate beam-to-column connections with diagonal stiffeners subjected to the cycling loading proposed by FEMA350/SAC protocol. Models were analysed with the ANSYS finite element analysis program. The study analyses the energy dissipation capacity, the stress and deformation state. The parameters are the direction of singular diagonal stiffeners, influence of crossing diagonal stiffeners and lack of stiffeners. The design of the connections is based on the strong column-weak beam principle.
Evaluation of the thermal performance of composite insulated panels with metallic skin through steady-state numerical analysis – Part 1
Authors: Măgurean A M
Published: September 2019

The energy performance of the buildings is a wide spreaded area on which many research is done nowadays. However, because of the relative new large scale interest on it, there still are subjects that have limited research data available. One of this topics is the thermal performance of composite insulated panels with metallic skin, usually a closure solution for industrial halls, production buildings, commercial buildings or even office buildings. Because of the mandatory request of the Energy Performance Certificates (EPCs) in the European countries and in Romania as well, is highlighted that is a lack of informations regarding the thermal behaviour of this type of technical solution and also, synthetic working data for building energy auditors, as linear thermal transmission coefficients values (Ψ-values) for the usually constructive details that compose a regular industrial hall is missing. Therefore, this paper aims to provide an insight about the thermal behaviour of this type of solution, by offering results of Ψ -values for four different dimensions of sandwich panels, which represents appropriate data for a thermal bridges catalogue that may be used directly by the building energy auditors.
Contributions to simulation of the non-permanent movement in sewerage collectors
Authors: Luca M , Luca A L , Scripcariu C F , Chirica S
Published: September 2019

The water movement of the sewer collectors is of a non-permanent type because of the variation in flow over time. Non-permanent movement in collectors is mathematically modelled by the Saint Venant equations. To solve the equation system, the characteristic method was used, provided that both equations are quasi-linear in the unknown h and Q. Non-dynamic contouring conditions are given by the hydraulic feature of the collectors / tanks located on the collector. Dynamic contour conditions are rendered by the collector-specific equations (river level effluent hydrograph, manoeuvring parameters of the boiler, manoeuvring characteristics at pumping stations, etc.). For the mathematical model implementation, a computational program was developed in the Matlab programming environment (Variation Gradual Collector Program). The program was used to simulate the non-permanent movement in the main sewerage collector “Cacaina” from the sewerage network of the city of Iasi. The simulation of the non-permanent movement was done in two collector evacuation scenarios (gravity and pumping). The analysis of the results obtained for scenario 2 highlights the differential operation of the eight collector sections separated by the side feeders. Simulation of the movement has highlighted the exceeding of the minimum and maximum values of the parameters imposed by the operating rules.
Numerical simulation of a heat exchanger using Al2O3 nanofluid and STES
Authors: Baran A I , Mateescu T , Luciu R S
Published: September 2019

The major energy crisis, predictable for the global economy, requires attentive research & development in order to grow energy performance, heat transfer and energy storage. It is a known fact that in the energy balance, the biggest share is in thermal energy and that justifies the continuous effort in the optimization of fossil fuel saving solutions and intense promotion of renewable energies. Use of the latter in heating and cooling systems as well as “waste heat” from different processes is consistent with the concept of sustainable development and results in reduction of conventional fuel consumption and emissions. Optimizing such a system can be made by replacing the usual storage material with phase changing materials and by using nanofluids as a secondary agent with the beneficial effect on heat transfer. In this paper we have studied a simplified multitubular heat exchanger, buried in the ground, having as a primary working fluid plain water and nanofluid, using Ansys. The nanofluid is composed of particles of A12O3 dispersed in water at a concentration of 1%. The study indicates an increase in convective heat transfer coefficient of nanofluid compared to water.
The effect of Stone Powder content of dolomite manufactured sand on the cement Hydration
Authors: Guo Jun-Hua , Li Gong-Zhou , Gao Chun-Yong
Published: September 2019

In this paper, the effects of different stone powder content (5%, 10%, 15%, 20%, 25%) of dolomite manufactured sand on the workability and mechanical properties of cement were studied. The influence of stone powder content on the hydration products and microstructure of cement were studied by XRD, SEM. The results show that the workability and mechanical properties of cement can be improved obviously when the content of stone powder is less than 10%, and the influence of stone powder on hydration products and Microstructure of cement is small.
Study on Properties of Binary Composite Cementitious Self-leveling Mortar
Authors: Dong W Y , Fang C Q , Hu R
Published: September 2019

The binary composite cementitious self-leveling mortar is an important development direction of modern building construction. At present, there are great differences in opinions on the mixing proportion of Portland cement and aluminate cement or sulphoaluminate cement in binary system and there are few literatures comparing the fluidity and strength of the two kinds of mortar. In this paper, the fluidity, flexural strength and compressive strength of the two kinds of mortar with different dosages were compared. The research results showed that the addition of aluminate cement and sulphoaluminate cement could reduce the initial fluidity and 20min fluidity of mortars, but the decreasing degree was different. The influence of different dosages of aluminate cement and sulphoaluminate cement on the flexural strength and compressive strength of mortars was obviously different. When the dosage of aluminate cement was 0-10%, the flexural strength and 1d compressive strength of mortar could be improved remarkably. When the dosage was higher than 10%, the strengths were obviously reduced, even lower than the strengths of Portland cement mortar. The flexural strength of the mortar increased with the increase of sulphoaluminate cement in the range of test dosages, but the 1d compressive strength had little difference. When the dosage was 10%-20%, the influences of the two kinds of cement on the 28d compressive strength of mortars were basically consistent and both could improve the 28d compressive strength of mortars.
Study on the effect of iron tailings manufactured sand powder content on cement Hydration
Authors: Guo Jun-Hua , Li Gong-Zhou , Gao Chun-Yong
Published: September 2019

In this paper, the effects of different stone powder content (5%, 10%, 15%, 20%, 25%) of iron tailings manufactured sand on the workability and mechanical properties of cement were studied. The results show that the strength of hardened paste can be improved by adding appropriate amount of stone powder. When the content of stone powder is 5%, The compressive strength reached 34.4MPa. The results of XRD show that the hydration products of cementitious materials mixed with stone powder are mainly ettringite, Ca(OH)2, hydro calcium, calcium silicate hydrate and quartz. The results of SEM show that proper amount of stone powder can effectively improve the porosity of composite cementitious materials, but the content of stone powder increases, the bond between stone powder and hydration products is not close enough, and the paste structure becomes loose.
Characterization of functionally graded concrete produced with fibres and recycled aggregates
Authors: Hu Tong , Chan Ricardo , Galobardes Isaac , Liu Xingzi , Moy Charles K.S. , Hao Jian Li , Krabbenhoft Kristian
Published: September 2019

Conventional reinforced concrete is widely used in the pavement construction despite its technical drawbacks, economic and environmental issues. To address these matters, the concept of functionally graded material (FGM) with materials that present changeable properties over its volume is adopted on concrete, generating functionally graded concrete (FGC). However, more studies are needed to understand how this material performs. In this study, six mixes of FGC concretes were produced to assess the effect of the recycled aggregate and different depths of the fiber reinforced layer on the flexural performance. Besides, the inductive method was performed to estimate the fiber content and distribution in the mixes. The outcomes of the study highlight the inductive method as a good tool to perform the quality control of the mixes and that FGC produced with recycled aggregates and fibers present great potential in terms of Serviceability Limit States (small deflection).
Heat and humidity performance of EPS and Rock wool board external thermal insulation system
Authors: Yang Z H , Guo P L , Chen X , Jiang W
Published: September 2019

A coupled heat and humidity transfer model of external thermal insulation wall is established, and the accuracy of the model is verified by the field test data. Taking Shanghai, a typical hot summer and cold winter area, as an example, this paper simulated and analysed the effects of different climatic conditions (winter and summer) and types of insulation board (rock wool and EPS) on the thermal and humidity properties of concrete-mortar-insulation-mortar external insulation wall. The results show that the temperature variation of the bonding mortar on the inside of the insulation board is much smaller than that on the outside of the insulation board due to the thermal insulation effect; the relative humidity of the bonding mortar layer in the external insulation system of rock wool can reach more than 80% within 7 days in summer, which has a high risk of falling off; and the relative humidity of the coating mortar layer can reach about 73% within 7 days in winter, which is likely to become mildewed; The resistance to moisture migration of rock wool is weaker than that of EPS.
Finite Element Analysis of PGM Process for Wafer Based Lens Array
Authors: Hu Yang , Zhou Jian , Li Mujun , Shen Lianguan
Published: September 2019

In order to study the PGM process for wafer based lens array, we established a 3D finite element model of glass wafer with lens array by using the submodel technique in ABAQUS. Then assessment criteria of the molded lens and influence of different PGM process parameters were investigated thoroughly. The obtained results show that during the molding stage, proper molding pressure can help the lens fill better and decrease the sag height deviation significantly. While during the annealing stage, holding pressure is essential for keeping the molded lens’ structure and position, but residual stress must be considered at the same time.
Study on the properties of PPS composite modified with Tungsten powder
Authors: Zhang Yi , Yang Weiwei , Zhuang Xiaohui , Liu Jiping , Han Jia
Published: September 2019

The tungsten powder (W) and polyphenylene sulfide (PPS) as the main raw material, through mixing, extrusion molding and extrusion molding method contrast, determines the extrusion method for the preparation of tungsten powder/PPS (W/PPS) composites, was studied by DSC, XRD and SEM after modification, the W powder for W/PPS material microstructure and the influence of thermal performance. W was mixed evenly in PPS, and the thermal decomposition temperature of PPS was increased.
Study on Application of Waste Polyethylene and SBS in Modified Asphalt
Authors: Peng Yang , Long Wu-Jian , Han Ning-Xu , Sui Li-Li , Wang Xue-Lian , Liu Yan-Hong
Published: September 2019

In this paper, modified asphalt was prepared by using waste polyethylene and SBS. Through the performance test of modified asphalt, it was found that waste PE (Polyethylene) and SBS (Styrene-Butadiene-Styrene) modified asphalt had good physical and mechanical properties. Through the asphalt mixture’s test, it was found that the waste polyethylene and SBS modified asphalt mixture had good high temperature stability, low temperature crack resistance and excellent fatigue performance.
First-principle and molecular dynamic calculation of concrete-filled steel tubular to introduce stainless steel technology
Authors: Guo Yaqin , Liang Duoqiang , Deng Yong , Zheng Xuemei
Published: September 2019

The concrete-filled steel tubular (CFST) structure offers numerous structural benefits, including high strength and fire resistances, favorable ductility and large energy absorption capacities. There is also no need for the use of shuttering during concrete construction; hence, the construction cost and time are reduced. These advantages have been widely exploited and have led to the extensive use of concrete-filled tubular structures in civil engineering structures. In the existing dozens of species types of stainless steel, some are suitable for concrete-filled steel tubular, some not. In this paper, the principles for selection of such types are studied, by both quantum mechanism and molecular dynamic method.
Evaluation of ionic liquid “greenness”-cytotoxicity of ionic liquids
Authors: Kong Q , Zheng S S , Liu T Q , Nie Y , Song K D
Published: September 2019

Ionic liquids have become a hot spot in research and application due to their own superiority. At the same time, the “risk” of ionic liquids has attracted more and more attention. The toxicity of ionic liquids varies according to the target. We have to obtain the toxicity data of ionic liquids on various organisms and cell lines, fill in the blanks of ionic liquid toxicity data and clarify the toxicity mechanism. Only in this way, can we lay the foundation for the design and synthesis of new ionic liquids that are truly non-toxic, environmentally friendly and meet functional requirements. In this experiment, 1-ethyl-3-imidazole diethyl phosphate ([Emim]DEP) was prepared by using 1-methylimidazole and triethyl phosphate as raw materials. The rat cranial anterior osteoblast cell line (MC3T3-E1) was used as the research object, using MTT method, fluorescent death-sense staining observation and flow cytometry to study the cytotoxicity of 1-allyl-3-methylimidazolium chloride ([Emim]DEP) type ionic liquid. This article aims to determine the median lethal concentration by the inhibition rate-concentration curve of [Emim]DEP type ionic liquid and measure cell survival index at this concentration.
Experimental study on electrical conductivity of carbon nanofiber reinforced concrete
Authors: Wang Tengjiao , Xu Jinyu , Bai Erlei , Chen Haowen , Liu Gaojie , Chang Sen
Published: September 2019

To study the effect of carbon nanofibers (CNFs) on the electrical conductivity of concrete, we used the four-electrode method to measure the resistance and resistivity of carbon nanofiber reinforced concrete (CNFRC) under different ages, different fiber content and different test voltages. The results show that the incorporation of CNFs into concrete can improve the electrical conductivity of concrete. The electrical resistance and electrical resistivity of CNFRC increase with the increase of concrete age, but the growth rate decreases gradually. The resistance and electrical resistivity of CNFRC decrease with the increase of carbon nanofiber content and the optimum dosage range is 0.1%-0.3%. The resistance and electrical resistivity of CNFRC decrease with the increase of test voltage, and when the test voltage is 1V~5V, the resistance and electrical resistivity decrease significantly.
Stability enhancement of flexible CZTSSe solar cells by using nanopore array substrate
Authors: Li Jinze , Hao Wenbin , Duan Jingjing , Xu Jie
Published: September 2019

Flexible CZTSSe solar cells were prepared on both thinned silicon substrate with and without nanopore array surface. The nanopore array structure could release thermal stress during the CZTSSe thin film preparation process, which improved the crystallization of CZTSSe thin film. The array structure could also absorb some bending stress during the bending test of CZTSSe solar cell, leading to obtaining a more reliable device. A flexible CZTSSe solar cell with only 14% efficiency loss after 3 times bending at 50mm radius was prepared by using nanopore array substrate.
Growth of Single-Layer MoS2 by Chemical Vapor Deposition on sapphire substrate
Authors: Yue Jiaojie , Jian Jiaying , Dong Pengfan , Luo Lei , Chang Fange
Published: September 2019

Single-layer molybdenum disulfide (MoS2) has attracted a significant amount of interest owing to its excellent electrical, optical, and mechanical properties. In this paper, we study that the effects of the distance between the molybdenum source and substrate as well as the substrate angle on the morphology, size, and structure of MoS2 films grown from molybdenum trioxide (MoO3) sulfide on sapphire substrates via the Chemical Vapor Deposition (CVD) by using Scanning electron microscopy (SEM), Raman spectra and Photoluminescence spectra (PL). On the results show that the distance between the substrate and molybdenum source affects the controllable growth of MoS2 films. When the substrate is too close to the molybdenum source, it results in increasing amount of non-reduced MoO3 particles which were deposited on the substrate. When the distance between the substrate and molybdenum source is too large, only a small amount of MoS2 is deposited on the substrate. High-quality MoS2 films can be prepared when the molybdenum source and substrate are 9.5 cm apart. When the substrate is inclined 30° and placed downstream of the molybdenum source with a distance of 9.5 cm, the size of the prepared single-layer MoS2 is approximately 100 μm, which is greater than that of MoS2 prepared on the horizontal face-up substrate.
Effect of Reaction Temperature on Silicon-Aluminum Alloy Prepared from Fly Ash
Authors: Bai Zhiling , Qin Bingke
Published: September 2019

The effect of carbothermal reduction of fly ash on the preparation of silicon and aluminium at different reaction temperatures was studied. XRD was used to analyze the phase of the reduction products at different reaction temperatures. The results showed that the products of carbothermal reduction fly ash included Al2O3, SiC, Al2SiO5, FeSiO3 and FeSi at 2073K. At 2123K, the products of carbon reduction fly ash were Al2O3, Al2SiO5, SiC, FeSi, Si and Al4.5FeSi. At 2173K, the main products of carbon reduction fly ash were Al2O3, Si, Al, SiC, FeSi and Al4.5FeSi. The diffraction peak intensity of silicon at 2173K was higher than that at 2123K, which indicated that increasing the reaction temperature was beneficial to the formation of silicon. Under the reaction conditions of 2223K and 2273K, the kinds of reduction products were the same, which were Al4.5FeSi, Si, Al, SiC and FeSi. The intensity of the diffraction peak of aluminium at 2273K was higher than that of aluminium at 2223K, which indicated that increasing the reaction temperature was beneficial to the formation of aluminium. In this experiment, with the increase of temperature, the degree of carbon reduction fly ash was more sufficient and 2273K was the optimum reaction temperature for preparing silicon-aluminium alloy from carbon reduction fly ash.
A new anti-freezing foam scrubbing agent technology research
Authors: Zhang Guangsheng , Duan Qiong , Cao Feng , Sun Ning
Published: September 2019

With the long delaying development and the higher pressure, the anniversary production of Yu-Lin Gas Field is reducing. Because of the lower temperature in the winter, the traditional foam scrubbing agent is not easy to foam that makes a poor drainage effect, lower developing and decreasing benefits. According to the common anti-freezer properties and parts of some development data, new anti-freezing foam scrubbing agent laboratory experimental study was put forward. Computed with the water production, when the new foam agent consumption is 200-400g/L, the roaming ration, foam stability and water carrying ability is greatly improved. When the foam agent consumption is 200g/L, the freezing point of foam scrubbing agent can reach to-10°C, and when 400g/L, it can reach to -25°C, which both satisfy the site temperature condition.
Progress in Preparation and Research of Hydrophilic Composite Nanofiltration Membrane
Authors: Yang Zhenhao , Zhang Liqing , Zhang Zhiqiang , Hu Jiyu
Published: September 2019

Most of the commercial nanofiltration membranes are composite nanofiltration membranes obtained by interfacial polymerization of polyamines and polyacid chlorides on ultrafiltration membranes with non-woven fabrics. During the operation of the membrane, membrane fouling is caused by inorganic salt scale, colloid, organic matter and other factors in the environment, resulting in a decrease in water quality and water flux so that a significant reduction in membrane life and an increase in operating costs. Therefore, it is necessary to improve the pollution resistance of the film. The hydrophilic modification of the membrane can improve the anti-pollution performance of the membrane. This paper discusses the preparation and research progress of the hydrophilic composite nanofiltration membrane from three aspects: new monomer development, active layer modification and new base film development and the current research content is summarized and some of the contents that need urgent research are proposed.
Control of the emission of NOx during coal combustion by inhibiting the formation of NOx precursor in the pyrolysis process
Authors: Zhang Kaixia , Shangguan Ju , Yang Song , Guo Sicong , Du Wenguang , Liu Shoujun , Chen Lili , Shi Pengzheng
Published: September 2019

NOX emitted from coal combustion cause serious pollution to the ecological environment. At present, controlling and reducing NOX emissions has become one of the most important technologies to control the pollutants in the atmosphere. Due to the formation of a large amount of NOX precursor HCN, NH3, char-N during coal pyrolysis, and these nitrogen species with O2 in the air cause the emissions of NOx during combustion. Therefore, it is of great significance to study the control of NOX precursors during coal pyrolysis. The addition of additives to coal has an important catalytic effect on the control of NOX precursors during coal pyrolysis. In this paper, the catalytic effect of additive Fe, Ca, Na on nitrogen transport during pyrolysis of raw coal or demineralized coal was discussed. It can be concluded that Fe, Ca, Na can catalyze the conversion of NH3, HCN and char-N to N2, thus reducing the NOX precursor in the pyrolysis of coal and reducing the emission of NOX in the subsequent combustion process. The result provides an important scientific basis for the control of NOX emission by reducing NOX precursor formed in pyrolysis during coal combustion.
Study on the action law of key influencing factors of magnetic field strength of magnetic filter material
Authors: Wang Xiaoyu , Wang Jiabin , Qiu Liping , Zhang Dong , Li Tianhang
Published: September 2019

In recent years, the application of magnetic field technology in the field of water treatment has been relatively mature. The common ways of adding magnetic field are external magnetic field and internal magnetic powder. In order to solve the problem of uneven distribution of magnetic field caused by external mode and easy loss of magnetic powder caused by internal injection mode, this paper studied a preparation method of magnetic filter material used in biological filter tank, and studied the key influencing factors such as composition, particle size, magnetization time and times that affect magnetic field strength of filter material. The results show that the nanometer Fe3O4 content has a great influence on the magnetic field strength of the magnetic filter material. When the content is 16.6%, the magnetic field strength of the filter material is the best. The larger the particle size of the filter material is, the less the magnetic structure of the surface magnetization vector is not collinear, and the higher the internal coercivity is, the higher the magnetic field strength of the filter material is. The magnetic field intensity of the filter material increased gradually with the extension of magnetization time, and basically became saturated after 60min. Repeated magnetization can improve the initial magnetic field strength of the filter material, but has little effect on the stable magnetic field strength after magnetic recession.
Control of the NOx emissions by metal additive in-situ catalyze the reduction of NOx during combustion
Authors: Chen Lili , Shangguan Ju , Ma Yuchuan , Zhao Cong , Liu Shoujun , Yang Song , Du Wenguang , Zhang Kaixia , Shi Pengzheng
Published: September 2019

The emissions of NOx during combustion causes serious pollution to the environment. It is especially important to reduce NOx pollution during coal combustion through clean coal utilization. The use of civil clean coke, which is mainly prepared by mixing metal additives with coal, is one of the ways of clean coal utilization. In this work, a series of coke samples with loading metal additives were prepared by physical method, and the NOx emissions were investigated in a fixed bed reactor. The results show that Na, K, Mg, Ca, Cr, Fe, Co, Ni and Cu play in-situ catalytic effects on the NOx reduction reactions. It is of great practical value and scientific significance to the comprehensive treatment of NOx and the clean utilization process of coal.
The Development of Shale Gas Modularized Surface Engineering
Authors: Chen Yingjie , Zhang Baosheng
Published: September 2019

Shale gas is one of the most important unconventional natural gas, which is an effective clean energy and has bright future. However, because of the characteristic of shale gas reserve, the conventional construction mode cannot be used to explore shale gas. With the development of 3D design software, the modularized engineering is gradually becoming the solution. The standardized engineering plays a key role to promote developing level of modules by several ways. These standardized modules can be transferred and reused in other wells. The whole project can be assembly design with standardized modules. The information technique is also applied into module engineering to improve the efficiency of operation monitoring and control. The shale gas surface engineering project is becoming like product, and it will cause a new evolution of project management and shale gas exploration.
Study on Solidification Process of ZL114A Wheel Casting
Authors: Zhang Yi
Published: September 2019

In this paper, three different solidification process design schemes of the ZL114A wheel casting are discussed, in according with the comparative analysis of metallurgical quality statistics, a solidification order from bottom to top and from outside to inside is attained by adjusting the chiller material and reducing the pouring temperature, which meets the HB963-2005IIcasting standards. The average tensile strength, yield strength and elongation of the T6 state are 340MPa, 260MPa and 6.5% respectively after the T6 heat treatment and the low temperature stabilization process. The average grain size of the primary α-Al matrix is about 86μm after adding 0.11%Sb element, the morphology of the binary and ternary eutectic Si phases that distributed nearby the grain boundary are spherical and elliptical, the fracture mechanism of T6 state shows a typical dimple fracture.
Study on Friction and Wear Performance of Bionic Coupling Surface Moving Pair of 45 Steel
Authors: Yang Zhuojuan , Liu Shuyi , Mao Chunyu
Published: September 2019

From the perspective of wear-resistant biological prototypes, the three non-smooth appearances of pits, stripes and grids are simplified abstractly. The shape, structure and material are organically coupled through reasonable mosaic and distribution. It was “replicated” on the surface of the 45 steel by using mechanical and laser processing methods. The wear test was conducted by using a microscopic wear tester. According to the test results, the wear mechanism of the biomimetic coupling morphology and the roles of the three coupling elements in form, structure and material in the wear resistance were analyzed. In this experimental condition, the wear resistance of the mesh shape is best under the same conditions; The coupling element of material plays the minimum of 3.52% in the wear resistance and the maximum will not exceed 64.2%; The pitch is between 0.65mm and 1.1mm. In the meanwhile, the wear resistance of the machined sample is higher than that of the laser processed smooth sample; When the distance is more than 1.2mm, the abrasion resistance of the laser processed sample is higher than that of the mechanical processing sample. This study has important reference value for the reasonable selection of coupling elements and coupling methods to improve the wear resistance of metal surfaces.
Evaluation of Pressure Pulsations in the SGMW B12 T255 Fuel Rail Assembly
Authors: Fu Li , Feng Suli , Xiang Weidong
Published: September 2019

The test is investigated magnitude of pressure pulsations in the SGMW B12 T255 fuel rail assembly and any effects on port to port flow distribution. The test bench is provided the fuel rail assembly required pressure and pulse width and period to simulate series of engine work status. The pressure pulsation results showed a significant change in the magnitude between 2000 and 3000 RPM. Flow distribution was further measured at 2000 RPM and 7ms, the finally test result is passed. After the vehicle test, it’s showed that reducing the flow rate from 1.8g/s to 1.5 g/s would further improve pulsation performance.
Research into EDM of Beryllium Foil
Authors: Wu You , Xiong Xuefeng , Pan Wenjie
Published: September 2019

This paper concerns with a machining experiment on the beryllium sample by electrical discharge machining (EDM), and the experiment proves the machinability in beryllium foil machining of EDM. A brass electrode was chosen for the machining, and the relationship between the tool wear and the process condition was revealed. By the alternation of the positive polarity machining and the negative polarity machining, the tool wear caused by electric erosion was furthest controlled. The foil with a thickness of (0.05~0.06) mm was achieved, and the Ra
of (0.18~0.20) μm and the P-V value of 0.78 μm were measured through white-light interference.
Simulation of pressure tank leakage based on PHAST
Authors: Yang Rili , Gai Ke , Yang Fengfeng , Zhang Guangsheng , Sun Ning
Published: September 2019

Chemical plants usually store hazardous chemicals in high-pressure or low-pressure storage tanks in the form of pressurization, liquefaction, and low temperature. The poisonous gas in the tank is easily diffused. If a leakage accident occurs, it will cause personal injury and environmental pollution. In this paper, based on the propane acrylonitrile project in an industrial park, Major hazard identifications were identified for the tank area (risk level is Level 1), then PHAST software was used to simulate the leakage and diffusion of acrylonitrile storage tanks. It was concluded that the greater the wind speed, the leakage pore and the more stable atmosphere, the greater the leakage and diffusion of hazardous areas. And timely and intuitive prediction of the diffusion process and scope of toxic gases provide a scientific reference for taking corresponding countermeasures and on-site control after the accident.
Method on condition assessment of pitch system based on fuzzy matter-element analysis
Authors: Zhao Shuangxi , Zhang Lei , Hou Lijun , Xiao Cheng , Zhu Xipan
Published: September 2019

In order to improve the real-time reliability of wind turbine and solve the effect of artificial factors, fuzzy matter-element analysis is proposed. The pitch system, which has high failure rate, is researched in this paper. The condition assessment model of pitch system is built in two steps: (1) To avoid the subjective judgment of the parameter distribution, this thesis uses 3σ rule and quartile analysis method to get the boundary data sets. The ANFIS algorithm is used to train the data to reduce the extreme value, and results of multi-feature fault detection are obtained. (2) Results from fault detection are applied in condition assessment model based on fuzzy matter-element analysis to realize the unification of fuzzy value of detection result and grade assessment. The method is applied to test the actual operation state of wind turbine. The results show that it can obviously reflect the pitch system and has better assessment effects.