bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of the Influence of Nano Metakaolin filler on Asphalt Binder Rheological Properties
Authors: Zghair Hussein H. , Joni Hasan H. , Mohammed Ali Ahmed
Published: January 2020

This paper investigates the effects of using nano metakaolin filler on the rheological properties of asphalt binder. In this work, asphalt binder of penetration grade 60 to 70 was prepared at three percentages (1%, 3%, and 5%) of asphalt weight using a high shear mixer fixed at 4,000 rpm for 60 min. Evaluations were then made of the properties of the modified asphalt binder such as the rotational viscosity, penetration grade, softening point temperature, temperature susceptibility, and ductility. The results of this work showed that the use of nano metakaolin filler as a modifier was helpful in improving asphalt binder properties. In general, it was found that the viscosity and softening point values increased, while the penetration value and temperature susceptibility (P.I.) values were reduced. The high shear mixing allowed good diffusion of nMK fillers into the asphalt binder, producing a homogenous composite binder. Additionally, the results showed that 5% nano metakaolin by asphalt weight was a reasonable additive to develop the rheological properties, increasing the softening point and viscosity values by about 14 and 77%, respectively while developing higher percentages of reduction in penetration value and ductility value of about 30 and 18%, respectively, making this more applicable to the construction of highway pavements in hot weather conditions.
Properties of engineered cementitious composite concrete (bendable concrete) produced using Portland limestone cement
Authors: Al-Mulla Ikram F , Al-Rihimy Ammar S , Abd Alameer Maitham S
Published: January 2020

Bendable concrete, also known as Engineered Cementitious Composite (ECC) is a type of ultra-ductile cementitious composites reinforced with fibres to control the width of cracks. It has the ability to enhance concrete flexibility by withstanding strains of 3% and higher. The properties of bendable concrete mixes (compressive strength, flexural strength, and drying shrinkage) are here assessed after the incorporation of supplementary cementitious materials, silica fume, polymer fibres, and the use of ordinary Portland cement (O.P.C) and Portland limestone cement (IL). Mixes with Portland limestone cement show lower drying shrinkage and lower compressive and flexural strength than mixes with ordinary Portland cement, due to the ratio of clinker existence being lower in the Portland limestone cement.
Enhancing a solar panel cooling system using an air heat sink with different fin configurations
Authors: Egab Karim , Okab Abdullah , Dywan Hashim S. , Oudah Saad K.
Published: January 2020

The temperature of a solar panel is an important parameter, which influences its performance and efficiency. Thus, development of solar panel cooling systems represents a new face of technology that may be used to improve power generation. Here, the reduction of solar panel temperature using an air-cooled heat sinks is studied numerically. The design of the heat sink comprises rectangular fins and rectangular fins with holes, made from a material with high thermal conductivity. The cooling efficiency is studied for different configurations of the heat sink, which are obtained by changing the fin numbers and hole distances. The numerical model is realized, using ANSYS-Fluent software, for a steady state whereby the ambient temperature is 25–35 °C, for different heat flux values. Increasing the number of fins and holes decreases the panel temperature. The reduction of panel temperature with fins is 50% compared to solar panels without fins.
A new multi-objective algorithm for underactuated robotic finger during grasping and pinching assignments
Authors: Jabbar Mortada A. , Bakhy Sadeq H. , Flaieh Enass H.
Published: January 2020

This study presents new kinematic and kinetic equations of grasping and pinching assignments, which have been derived to consider the angles for the ternary solid links of a three-phalanx linkage underactuated robotic finger mechanism. Numerical and experimental investigations are conducted. Numerically, eight design criteria are adopted for finding an optimal solution using a new multi-objective function algorithm (grasping stability percentage, forces of grasping, squeezing force, grasping assignment mimic function, transmission angle for grasping assignment, mimic function for pinching assignment, transmission angle for pinching assignment and pinching force). The gradient descent method, comprising three steps, is used to find the optimal geometric parameters. These parameters are modified to fabricate the prototype of the robotic finger. Experimentally, the three-phalanx linkage finger is adjusted via the addition of a DC motor at the second linkage coupler link, having four bars for length adjustment for performing the aspect of human finger through the grasping and pinching assignments. The results show that adding ternary solid links to the robotic finger enhances the grasping stability and assists the complete embrace of objects, particularly objects that are smaller than those for the same finger without ternary solid links. In addition, the results indicate that the pinching force enhancement is 7–25% with reduction of the objects’ sizes, due to the ternary of solid links.
Effects of heat treatment, quartz additions and particle size on the properties of enamel with low-alloy steel substrate
Authors: Abdulrahman Ibrahim K. , Mahmood Ibtihal A. , Jabor Adnan S.
Published: January 2020

A vitreous enamel coat is a thin layer of glass, typically a few hundred microns in thickness, which is fused onto a metal substrate. The glass used for vitreous enamelling is referred to as the ‘frit’ and is formulated from a wide range of inorganic raw materials including quartz, borax and titania. This research called for the preparation and development of a mixture of ceramic materials, consisting of various metal oxides, for coating low-alloy steel plates with a carbon percentage of 0.18%. A single coating layer was used with a dipping method. Before dipping, the samples were treated with sand blasting. The effects of heat treatment temperature and time, the percentage of quartz additions and coating powder particle sizes were all studied. It was found that crystalline phases (such as (SiO2), (Na2O-Al2O3-TiO2-SiO2), (Li5AlSi2O8), (TiO2)) were developed in the structure of the coating after heat treatment processing. The results showed significant improvement in all properties of coating hardness, adhesion, thermal stability and chemical resistance by increase in the heat-treating temperature and time; the best results were obtained in the properties of the coating with the treatment temperature at 650 ° C, a time of 120 minutes and 15% quartz addition. The results also showed a clear effect of the particle size of powder coating on the properties of hardness and adhesion. When the particle size decreased, the mechanical properties (hardness, adhesion) and thermal stability improved. The results indicated that the increase in coating particles’ size led to an increase in the coating thickness.
Comparability Study on the Effects of Curing Approaches on the Mechanical Behaviours of Reactive Powder Concrete
Authors: Taher Muntadher J. , Alsaad Aymen J. , Radhi Mushtaq Sadiq
Published: January 2020

Reactive Powder Concrete (RPC) is the most commonly used type, known as Ultra High-Performance Concrete (UHPC). This type of concrete requires very low water/binder ratios to ensure that the microstructure is very dense and impermeable. Thus, it also needs special types of curing to ensure its high strength, high durability, and dimensional stability. The main target of this study is thus a comparison of different curing regimes to investigate their impacts on the mechanical performance of RPC. Three different curing regimes, Normal Curing (NC), Steam Curing (SC), and Boiling Curing (BC) were thus adopted in this study. To assess the mechanical behaviour of RPC, compressive strength, direct tensile strength, and density measures were implemented for the different curing regimes and SC and BC were compared with normal curing at various curing ages. The investigation results revealed that, among the three different curing approaches, the steam curing method most significantly enhanced the mechanical behaviour of the RPC, particularly compressive strength.
Microstructure, mechanical and corrosion properties of the 50%Ni-47%Ti-3%Cu shape memory alloy
Authors: Abbas Dania Fadhil , Resan Kadhim Kamil , Takhakh Ayad M.
Published: January 2020

in this study, the mechanical, microstructure and corrosion properties of Nickel-Titanium-Copper shape recovery alloys were investigated. The alloy was prepared by the powder metallurgy method, where powders of 50% Titanium, 47 % Nickel and 3% Cupper were mixed and cold compacted at (600,700 and 800) MPa to form cylindrical samples of (11mm diameter × 16.5mm length) and (11mm diameter ×5 mm length). After compaction process the specimens had more green strength for handling. The samples were subsequently sintered at a temperature of (850,900 and 950) °C for a period of 5 hours in an electric vacuum tube furnace. Multiple tests were conducted on the alloys including porosity measurements, scanning electron microscopy (SEM), compression strength, shape memory effect and corrosion rate test. The results indicate improvement in compression strength and shape memory effect with low sintering temperature and high compacting pressure as well as reduction in the corrosion rate.
Numerical Study of the Boundary Layer Separation Control on the NACA 0012 Airfoil using Triangular Rib
Authors: Al-Jibory Mohammed Wahhab , Ali Shinan Hussain Abed
Published: January 2020

This study includes a numerical simulation to investigate the aerodynamic behavior of the air flow around the surface of the NACA0012 airfoil, with and without a triangular rib. The triangular rib was used on the upper surface of the airfoil with size of 2% of the total chord length and variously located at 50, 70 and 90 percent of the chord length from the leading edge, separately as a passive control technique. Workbench-Fluent 17.2 version software was used to simulate the flow at 7 m/s freestream velocity (Re = 78,000), various attack angles (0˚ to 22˚) and chord length of 168 mm. The results indicated the presence of the triangular rib on the airfoil’s upper surface, at low angles of attack (less than 12˚), was a negative for the lift and drag results, at the angle of 12˚ it was a positive only for the location of 90%, while at the higher angles it was a positive for all locations and for all results where the lift increased and drag decreased. Therefore, the NACA0012 airfoil’s performance (lift to drag ratio) was significantly enhanced but, at 22˚, it had a very small effect for all results. It was concluded that the rib’s presence at 50% location delayed the stall angle by two degrees (from 14˚ to 16˚).
Study and optimization of the mechanical properties of PVP/PVA polymer nanocomposite as a low temperature adhesive in nano-joining
Authors: Taher Ahmed A. , Takhakh Ayad M , Thahab Sabah M
Published: January 2020

This paper presents a study of the effects of temperature, curing time and silver nano-particles (AgNPs) on the concentration of the PVP/PVA nano composites on shear force of adhesive nano-joining (ANJ). Low temperature (LT) ANJ of copper–copper (Cu–Cu) at the temperature values of 200, 215, 225, 240 and 275°C and curing times of 10, 20 and 30 minutes, under fixed pressure (5 MPa) are investigated. Higher shear strength value is found at a temperature value of 227 °C and time extent of 10 minutes. It is noted that for an AgNPs concentration of (5%wt) a maximum value of shear strength (2180N) is reached. These results indicate that resistance will increase with raising of the heat up to 227 °C, then followed by a decrease in strength up to 275 °C at a curing time of 10 minutes. The results have been optimized with Neural Network (NN) for accuracy.
A consecutive heuristic algorithm for balancing a mixed - model assembly line type II using a (W-TAWH) model developed for straight and U-shaped layouts
Authors: Aufy Samah A. , Kassam AllaEldin H.
Published: January 2020

The development of assembly lines in manufacturing systems has evolved due to consumer expectations and a growing and increasingly competitive global market. The assembly line balancing problem (ALBP) is well recognised in manufacturing and may arise when tasks are assigned to the workstation. In this paper, a problem statement is structured by assigning a task to a worker in a suitable workstation, subject to some constraints, in order to reduce the cycle time and improve performance. This is a new approach, based on worker and task assignment and is thus a worker – task assigned to workstation heuristic model (W-TAWH). It has been developed for straight and U-shaped models. The methodology is described as two stages, the input related data stage and assignment stage. Firstly, the focus is on combining precedence diagram and generating the sequence vector procedure. The second stage comprises development of comprehensive mathematical formulae for the consecutive algorithm to address the straight and U – shaped balancing problem, with minimization or maximation of relevant criteria. This generates performance evaluation criteria according to the number of tasks and workers assigned to the workstation, and these criteria are integrated into a single score using a desirability function approach. Finally, the performance of the developed algorithm is validated through a numerical example. We tested 24 alternative solutions and the fourth solution (1-4-1) achieved the highest score (0.726), which represented the following assignment variables: straight layout, minimum total number of successor tasks rule, and four workers. The performance evaluation is represented by the lower bound of cycle time and upper bound of efficiency.
Experimental Investigation of the Horizontal Double Pipe Heat Exchanger Utilized Phase Change Material
Authors: Dukhan Wisam A. , Dhaidan Nabeel S. , Al-Hattab Tahseen A.
Published: January 2020

The melting of a phase change material (PCM) inside a horizontal concentric two-pipe heat exchanger is experimentally investigated. The PCM RT-42 (Rubitherm) is contained in the annular space between the inner tube of diameter 25 mm and outer insulated shell of diameter 75mm. The hot water as a heat transfer fluid (HTF) flows inside the inner tube at different temperatures, 60, 70 and 80 °C. The experimental setup involves twelve thermocouples to record the transient temperatures of PCM at different locations. Also, the progress of the solid-liquid front during the melting process is tracked photographically by a digital camera. The experimental findings revealed that the heat conduction, accompanied by the same melting rate around the inner tube of the heat storage unit, is predominant at the beginning of the melting process. As time progresses, the natural convection role is strengthened and causes a higher melting at the top part than is shown at the lower part, which is still dominated by conduction. Also, the melting rate is directly affected by the temperature of the HTF. The melting time is reduced by about 27% and 46% when the HTF temperature varies from 60 to 70°C and 80°C, respectively. The variation of the Nusselt number during the melting process is evaluated. There is a positive influence of the HTF temperature on the energy stored by the PCM.
The Effect of Turbulent Flow of Fluid Containing Nano - particles of Al2O3 on Free Vibrations of Pipe for Elliptical Cross Section at Different Boundary Conditions
Authors: Al-Raheimy N H
Published: January 2020

In this research the Rayleigh method was used to estimate the natural frequency of elliptical cross-sectional pipe where the major axis (2a) and the minor axis (2b) conveyed water containing nano-particles of Al2O3 at the ratio of volume concentration (Φ% = 0, 0.1, 03, 0.5). The study examined different boundary conditions (clamped – clamped, clamped – pin, clamped – free and pin – pin ). The ratios were firstly b/a=1, 2, 3, 4, 5 and then a/b=1, 2, 3, 4, 5 for different thickness “t” (1mm, 2mm), where the half major axis “a” (1cm, 2cm ) and the half minor axis “b” (1cm, 2cm) at the length of pipe “L” (1m), and using various pipe materials (PVC, aluminum and steel). This study predicted the natural frequency (ωn) and critical velocity (VC) which in the first case was larger than that at the second case for any construction of pipe. The natural frequency decreased slightly with the increase in the ratio (Φ% ). Finally, the natural frequency and the critical velocity were changed directly with increase of the ratio (b/a) while the inverse changes occurred with the increase of the ratio ( a/b) for PVC pipe but increased little for aluminum and steel pipes, due to different physical properties. Results have been compared with published theoretical and experimental results and found to conform.
The Effect of Prestressing Strands on the Shear Behaviours of Steel Beams
Authors: Yousif Mustafa Ahmead , Mahmoud Kamal Shahada , Atshan Ali Farhan
Published: January 2020

Seven simply supported steel beams were tested to examine the effects, in terms of strengthening, of external prestressing of strands on the shear behaviour of steel beams. All beams had the same steel section and clear span length and strengthening was implemented using two external prestressing strands. The tested beams were divided into two groups based on the presence of the external prestressing strands: the first group thus consisted of just one steel beam, as a reference, while, the second group had six steel beams strengthened by external prestressing strands divided according to the eccentricity location of a prestressing strand with jacking stress fpj = 1120.061 MPa. During the tests, it was found that the shear load strain curves for the tested beams were slightly stiffer than for the reference beams and that the percentage of stiffening increased with any increase in the eccentricity of strand locations from the shear points; the maximum shear load increased by 0.521%, 29.565%, 38.26%, 61.739%, 24.347% and 86.956% with an increases in the eccentricity location from (0 to 165) mm compared to the reference beam. The maximum shear strain increased by 9.664%, 3.553%, 8.121%, 62.436%, 37.563% and 13.451% with an increase s in the eccentricity location from (0 to 165) mm respectively as compared with the reference beam.
Influence of Sulphate and Chlorides Acidic Media on Mechanical and Corrosion Behavior of Fly Ash Particulate Reinforced 2024 Al/TiO2 Composites
Authors: Salman R A , Ajeel S A , Zedin N K
Published: January 2020

This research studied the corrosion behavior of 2024 Al/2%TiO2 with different additions of fly ash in 0.1N H2SO4 and 0.1 N HCl media. Using a liquid metallurgy route (stir casting technique) 0, 2, 4 and 6 wt.% of fly ash were added to 2024 Al/2%TiO2 and the density and corrosion potential of the samples was evaluated by potentiodynamic polarization. The highest corrosion current density (7.437 x 10-1) was obtained in 0.1 N HCl media while the corrosion current density in 0.1N H2SO4 media was 2.276 x 10−3. The corrosion current density values of 2024 Al/2%TiO2 alloy rose with increase in the fly ash addition from 0.305 x 10−2 to1.08 x 10−2 as a result of the micro galvanic coupling between the matrix alloy and the reinforcement or conducting interfacial products. Micro-Vickers hardness of the composite increased from 120 V to 160 V with increasing fly ash content. The values of yield strength increased from (231MPa) to (279 MPa) and the values of ultimate tensile strength (UTS) were increased from (136MPa) to (184MPa) with increase in the percentage of fly ash.
Experimental study of atmospheric water collection powered by solar energy using the Peltier effect
Authors: Kadhim Thualfaqir J. , Abbas Abdalrazzaq K. , Kadhim Hayder Jawad
Published: January 2020

A small-scale prototype with one thermoelectric module was constructed to collect water from the atmosphere, and studied experimentally. It was driven by a solar panel module and operated by reducing the cold side temperature to less than the dew point temperature of ambient air. The system was designed and assembled depending on the capacity of the Peltier device, of dimension (4×4 cm^2), and energy needed. The system consisted of a heat sink, extended cold surface, Peltier device and fan, which were housed in a vertical rectangular section duct and used with different air temperatures, airflow rates, and humidity levels. A numerical model was used to study the temperature distribution on the cold side, which was applied to size the cooler to estimate the water production rate. The results suggest that the water production rate increased with the increasing of the moisture level in the air. The tests also showed that increasing the amount of air flowing on the heat sink increased the amount of water collected and enhanced the transfer of heat on the hot side. The achieved results show that the collection of water is reasonable with the proposed thermoelectric method using solar energy.
Applying the Analytical Hierarichy Process and Weighted Sum Model for Small Project Selection in Iraq
Authors: Al-Bayati Israa Ibrahim , Al-Zubaidy Sawsan Sabeeh
Published: January 2020

The assessment and selection of small projects are usually carried out using commercial, official, environmental and marketing data before the investment decision is made. Small projects are among the most important sources of job opportunities and revenue in many nations. The contribution of small enterprises the provision of work has been a controversial issue around the world, it is therefore important to clarify how best to choose between projects. This paper shows an example from Karbala governorate, which demonstrates project prioritization through two project selection methods. A questionnaire was completed and scores were computed for prioritizing potential projects. The first category used an analytical hierarchy process (AHP) model for investment selection when comparing a number of options (alternatives) with respect to specific criteria, then investment with the highest weight was used to select small projects in this field for second stage transference. The second category used a weighted sum model (WSM) for top small project selection, which operated by obtaining all small project scores, and declaring that with the highest project to score to be the best small project. After combining the data and research procedure, we found that the best option from among small projects in Karbala was an industrial dairy factory.
Experimental Study on Modified Shielding Functional Mortar
Authors: Gao Yi , Lu Yingjian , Huang Jing
Published: January 2020

The mortar board was prepared with the content of reduced iron powder, thickness and shielding fabric as variables. The results showed that appropriate content of reduced iron powder could improve the shielding efficiency of mortar, and the peak shielding efficiency of 10mm thick specimens with a dosage of 300kg/m3 reached 16.9db and the 20mm-thick specimens reached 17.1db. The 10mm-thick specimens with shielding fabric reached 73.5db, and the 20mm-thick specimens reached 59.3db
China Network Public Opinion Guidance Research Hotspots and Development Situation Analysis-Quantitative Analysis Based on CiteSpace Knowledge Map
Authors: Liu Yanfang , Wang Pengyao
Published: January 2020

Through the quantitative analysis of related literatures, it reveals the research hotspots of china network public opinion to guide this research field, and provides theoretical research for the further development of academic research in this field and the improvement of China’s network public opinion guidance work level. Using CiteSpace software to use 2009-2018 as the specified time period, the Chinese literature on the theme of “Network Public Opinion” in China Knowledge Network (CNKI) is used as the source data, based on CiteSpace’s visualization technology, the key Word clustering maps, research organization timing maps, and institutional and author cooperation networks are analyzed. It is concluded that the focus of China’s network public opinion guidance research mainly focuses on the four aspects of the main body, object, carrier and content of the network public opinion.
Effects of Magnesium-Calcium Alloys with Different Calcium Content on Their Mechanical Properties
Authors: Wang Yanan , Liu Guodong , Wei Yukun , Qiao Yang
Published: January 2020

Compared with traditional medical metal materials, magnesium alloys have the characteristics of small density, small elastic modulus and high specific stiffness. In order to study the effect of the addition of calcium on the mechanical properties of magnesium alloys, the tensile test and hardness test of magnesium-calcium alloy were carried out. The stress changes during the tensile test of magnesium alloy were discussed, and the microstructure of its section was further observed, so as to compare the effects of different calcium content on the mechanical properties of magnesium alloy. The results show that the addition of calcium content increases the hardness and tensile strength of the magnesium alloy, and it tends to rise first and then decrease.
Research on Preparation Process of Graphene by Modified Ball Milling and Its Thermal Properties
Authors: Yu Quanmao , Liu Qiurong , Li Xiaoxia , Chen Zhong , Ren Tao , Chen Zhenyu , Huang Zhengyi
Published: January 2020

Graphene is a focus for its excellent properties. The high efficient low cost preparations of high pure Graphene are bottlenecks in Graphene application field. This paper reports a modified mechanical milling high pure Graphene preparation method. The method has the characteristics of less cost and can scale-production. The XRD, TEM and TG/DTA are used to character the properties, especially the thermal properties of Graphene prepared by the method.
Fabrication of Bi2MoO6 Photocatalytic Fibers via Wet Spinning and Enhanced Photocatalytic Activity
Authors: Sun Jun , Zhang Yan , Tian Xiaobing , Yang Meijun , Yang Xiaolong , Yu Jianqiang
Published: January 2020

In this paper, Bi2MoO6 photocatalytic fibers were fabricated by wet spinning method and the photocatalytic activity was found to be enhanced significantly. The Bi2MoO6 powders were prepared by hydrothermal process at different pH (0.4, 6, 8, 10), which is recorded as BMO-0.4, BMO-6, BMO-8, BMO-10. The powders were then mixed with sodium alginate colloid, and fabricated into photocatalytic fibers by wet spinning. The samples were recorded as FB-0.4, FB-6, FB-8, FB-10, respectively. The crystal phase, morphology and photophysical properties of the fiber samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and laser particle size analysis (LPSA). In order to investigate the photocatalytic performance of the synthesized photocatalysts, RhB and formaldehyde were used as simulated water pollutant and air pollutant, respectively. It showed that the efficiency of the degradation of RhB over BMO-10 was 75%, while that enhanced to 85% over FB-10. It should be noted that the content of photocatalyst in the fiber FB-10 was only 1%. The degradation efficiency of formaldehyde in FB-10 sample reaches 92%.
Application of Trace Property in Fire Cause Identification
Authors: Wang Liantie , Meng Qingshan
Published: January 2020

In the investigation of fire causes, there are many kinds of weld marks extracted from the fire site, such as the first and second short circuit weld marks. The relationship between the melting property and the cause of fire can be identified according to the different microstructure characteristics of the weld marks formed on the copper and aluminium wires. Therefore, in the determination of the cause of fire, the nature of the weld mark will directly affect the result of the determination, and sometimes a completely different conclusion will be drawn. However, sometimes in the same fire scene can be extracted from more than one weld mark, and the nature of the weld mark is not the same, which will bring certain difficulties to the fire cause identification work, so the organic combination of all kinds of weld mark, reasonable use, in order to better complete the fire scene cause identification work.
CuInS2 Quantum Dots-based Off/On Probe for Detection of Cetyltrimethylammonium Bromide and L-Cysteine
Authors: Liu Yitong , Guo Zhongkai , Tai Qunxi , Tu Zaiqian , Bai Hanyu , Liu Siyu
Published: January 2020

We developed a convenient method for cetyltrimethylammonium bromide (CTABr) detection based on the quenching phenomenon of CuInS2 quantum dots. There existed a good linear relationship between the fluorescence intensity of CuInS2 quantum dots and CTABr concentration from 0.08μmol/L to 6μmol/L with a detection limit of 25nmol/L. The quenched fluorescence intensity of CuInS2 quantum dots by CTABr could be recovered by L-cysteine, which could be also used to detect L-cysteine from 0.05 to 100μmol/L with a detection limit of 20nmol/L.
Effect of Inhomogeneity of FGM Coating on Contact with Adhesion under the Axisymmetric Indenter
Authors: Yang Fan , Liu Tiejun
Published: January 2020

The contact with adhesion between the FGM coating and axisymmetric indenter is probed into in the present paper. Coating is made of FGM with linear varying modulus. Poisson’s ratios of coating and substrate are chosen to 1/3. The Maugis-type adhesive model is used to describe the adhesive interaction in the adhesion zone. According to the basic equations for axisymmetric problem, the controlling singular integral equations of the contact problem with adhesion are gained by making use of Hankel integral transformation. These integral equations are solved by applying a numerical collocation technique. The results show that the contact damage and deformation on the coating surface can be reduced by adjusting the inhomogeneity of the coating.
Design and Implementation of Fixed Length Profile Cutting System Based on Mitsubishi Q Series and CC-Link Field Bus Control
Authors: Wang Liqing , Cheng Yimin , Hou Xujie , Wang Chang
Published: January 2020

In order to achieve the fixed length cutting of profiles, this paper designs a fixed length cutting system using Mitsubishi Q series PLC as the main controller, Fx series PLC as the slave controller and CC-Link as the field bus. Based on the working principle of the equipment, the paper analyzes the operation process of the cutting system. Based on PLC controller, stepping motor and servo motor, the hardware design of the system is carried out. A mathematical model for calculating the initial remaining length was established and the software was designed. The use indicates that the work intensity of the operator is greatly reduced, the yield is improved, the production cost is reduced, and the application prospect is good.
Micro-mechanism on the Metal Materials with the Fatigue Propagation
Authors: Li Molan
Published: January 2020

Low stress failure due to fatigue is one of the most common and common forms of component failure. Especially for aerospace and Aeronautical products, the system structure is complex, the environmental conditions are complex, the application of new technologies and materials is significant, and the investment of a single product is high. Therefore, the abnormal low stress damage of individual structures often causes catastrophic losses. In practice, most of the components with defects are not easy to find because of the stress damage caused by the continuous crack growth under fatigue load. Therefore, the study of fatigue crack and growth rate has great practical significance. In this paper, the general law and microscopic mechanism of crack growth of metal structural materials under normal temperature and transverse fatigue load are studied.
Research on Preparation of Nano-porous Lithium Iron Phosphate for Lithium-ion Battery Electrode Materials
Authors: Yu Quanmao , Ren Tao , Li Xiaoxia , Chen Zhong , Liu Qiurong , Chen Zhenyu , Huang Zhengyi
Published: January 2020

Citric acid, nitric acid, ferrous phosphate and lithium carbonate as raw materials, the precursor Fe3(PO4)2 were synthesized by precipitation method, and nano-porous lithium iron phosphate (LiFePO4) was prepared by modified sol-gel method. The influence of pH to purity and yield of precursor Fe3(PO4)2 and sintering temperature to purity of LiFePO4 were studied. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy techniques (TEM) were used to character the phase and morphology of nano-porous lithium iron phosphate (LiFePO4).
Effect of Repeated Cutting on Low-frequency Torsional Vibration Tapping Torque
Authors: Li Wenzhao , Li Zhizun , Han Fengqi
Published: January 2020

Low-frequency torsional vibration tapping can significantly reduce the tapping torque, which is an effective method to solve the problem of precision machining of small and deep threaded holes on difficult-to-cut materials. In this paper, the mechanism of repeated cutting of low-frequency torsional vibration tapping is studied by comparing continuous tapping with low-frequency torsional vibration tapping on titanium alloy, and the influence law and mechanism of the process parameters such as repeated cutting times and net cutting angle on the tapping torque are studied through the vibration tapping experiments on different materials. The research results show that under the premise of ensuring the processing efficiency, smaller net cutting angle and larger repeated cutting times should be selected to obtain a good process effect.
Study on Shearing Characteristics of Circumferential Joint Rebate of Stagger-Jointed Shield Tunnel
Authors: Lu Cirong , Zhou Huaizhi , Huang Long
Published: January 2020

At present, the design and construction of shield tunnels often adopt stagger-jointed form with rebate, and improving the mechanical properties of rebate is the key to solving the problem of leakage of tunnel structure and other diseases. This paper aimed at circumferential joint rebate of staggered shield tunnel segment, established the local model of discontinuous contact of three-dimensional solid joint to analyse the influence of rebate and the length and inclined angle of it on shear resistance of joint. The result shows five points: (1) When the segment joint is sheared, the greater the axial force of the joint, the stronger the frictional shear resistance. (2) Setting rebate in joints can reduce the number of dislocations in the stage of rapid development of dislocation and increase the shear resistance of joints. (3) The length of rebate has little influence on the shear strength of joints. (4) The angle of inclined plane of rebate has a great influence on the shear resistance of joint. The smaller the angle of inclined plane, the larger the peak shear force and the corresponding dislocation, while the greater the local stress. (5) When the inclined angle increases, the stress of rebate is more uniform, which can prevent the damage of rebate.
Effect of the Properties of Basalt Fibers Aging in Salt Solution
Authors: Zhang Qichang , Yan Tan , Luo Lida , Wang Qingwei , Liu Jin
Published: January 2020

Basalt fiber is widely used in various fields such as military industry and civil use due to the characteristics of high strength, high temperature resistance and good chemical stability. In this paper, the aging of basalt fiber immersed in different concentrations of NaCl solution at different times was studied. The surface morphology and structure changes of basalt fiber brine after immersion were studied by scanning electron microscopy and Fourier transform infrared spectroscopy. The Fracture strength and weight loss rate of basalt fiber were used to characterize the salt water corrosion resistance of basalt fiber. The results showed that the surface of fiber was slightly corroded and ion exchange occurs in the solution when basalt fiber was soaked in NaCl solutions. The tensile strength of basalt fiber increased first and then decreased with time. It was inferred the ion exchange resulted in surface compressive stress increase the strength of the basalt fiber just like as tempering principle of glass.
High-temperature Creep Behavior of 12Cr1MoVG Steel
Authors: Pan Jinping , Zhu Chaoming , Zhu Xinwei , Tan Lianjiang
Published: January 2020

Heat-resistant steels are key materials for the construction of boilers and high-temperature pipes. Herein, high-temperature creep behavior of 12Cr1MoVG steel has been studied. Creep tests over a long period of time were carried out for 12Cr1MoVG steel samples at varied temperatures. The activation energy for the creep of 12Cr1MoVG steel was evaluated based on the changes of creep rate with temperature when the steel was subject to various stresses. The creep mechanism of the steel has been elucidated by analyzing the relations between the minimum creep rate and the stress. In addition, continuum damage mechanics (CDM) model-based calculation agree well with the strain versus creep time curves obtained from the creep tests. The creep behavior of the 12Cr1MoVG steel at high temperatures has been perfectly described by means of long-time creep tests and mathematical modelling.
Fatigue Performance of T-joint with Complete Weld Details
Authors: Liu Xi , Meng Qingyu , Wang Can , Huang Song
Published: January 2020

The fatigue properties of T-joint of Q345 steel commonly used in construction machinery are studied. The fatigue life of T-joint with complete weld details is analyzed by nominal stress method and the equivalent structural stress method respectively, and compared with the test results. The results show that under the condition of stress ratio R=0.5, the fatigue crack of T-joint with complete weld details often occurs at the weld root of the arc extinguishing and propagate along the weld throat. In production, arc extinguishing should be avoided in key parts. The nominal stress method used to predict the fatigue life of T-joints with complete weld details is dangerous, while the fatigue life of T-joint analyzed by the equivalent structural stress method is basically consistent with the test results.
Preparation and Properties of Poly (Silicon-Containing Arylacetylene)/Attapulgite Foams
Authors: Wu Jiadong , Dong Shilong , Yuan Qiaolong
Published: January 2020

Poly(silicon-containing arylacetylene) (PSA) syntactic foams were prepared by thermally expandable microspheres (EM) in the silicon-containing arylacetylene (SA) resin during curing. The morphology, porosity, thermal and mechanical properties of the foams were studied. Furthermore, the PSA foam was reinforced by attapulgite (ATT) nanoparticles to fabricate the PSA/ATT composite foam. The results display that the density, compressive strength and thermal stability of the PSA foam decrease with increasing EM content in the matrix, but the temperature at 5% weight loss in N2 is still higher than 560°C, and the residual yield at 800°C is larger than 89%. With addition of 10 g ATT in the 100 g matrix, the average specific compressive and flexural strength of PSA/ATT foam are 31.4 MPa g-1cm3 and 33.6 MPa g-1cm3, respectively. The thermal conductivity of the composite foam can decrease to 0.064 W m-1 K-1 and has a density of 319 kg m-3.
Comparisons of Models for Predicting Permeability from Nuclear Magnetic Resonance (NMR) Logging Data in Heavy Oil-bearing Reservoirs
Authors: Zhang Wei , Li Qi
Published: January 2020

Permeability prediction always faces great challenge, because it cannot be directly measured from any well logging data. The statistical methods had been widely used. The accuracy was too low to be used. The nuclear magnetic resonance (NMR) logging data was considered to be effective in permeability prediction, and many models had been proposed. However, the NMR logging data was heavily affected by the viscosity in heavy oil-bearing formations. The reliability of the permeability estimation model in heavy oil-bearing reservoirs needed to be checked to make them much valuable in field application. In this study, 24 core samples, which were drilled from the heavy oil-bearing reservoirs of the Zhujiangkou Basin in South China Sea, were applied for NMR and mercury injection capillary pressure (MICP) experimental measurements. The classical permeability prediction models of Timur-Coates model and Schlumberger Doll Research (SDR) model were calibrated. Meanwhile, the permeability prediction model based on the Swanson parameter was also established. These three models were applied in field applications to verify the reliability. Comparisons of the predicted permeabilities by using these three models with the core derived results illustrated that the Swanson based permeability model was widely used. Whereas the permeabilities estimated by using the Timur-Coates and SDR models were underestimated. The Swanson based permeability model was given priority to be recommended.
Development of an Anti-corrosion and Anti-pollution Stone Material
Authors: Lu Yuning , Lin Xiang , Zhao Pei , Zhang Yanhao , Li Enyao , Zhao Su
Published: January 2020

Stone is a non-renewable resource. In order to implement sustainable development in the field of building materials, it is necessary to carry out feasible protection for the existing stone. At present, the performance of the protection materials is relatively single. How to give consideration to both waterproof and anti-corrosion and anti-pollution properties is the focus of this study. Using tetraethyl orthosilicate (TEOS) as silicon source and adding appropriate modifier (silicone oil), the modified silicon stone protective material was prepared by sol-gel method. The ratio ranges of water, ethanol, hydrochloric acid and TEOS were determined by experiments, which were 1:1, 1: 1 ∼ 1: 2, 1: 10 ∼ 1: 20 respectively, the reaction temperature was 60°C, and the reaction time was 3.5h. Under the experimental conditions, adding modifier hydroxyl silicone oil (0.2%) can improve the anti-corrosion and stain resistance of stone protection materials.
Ecological Toxicity of Triclosan (TCS): A Review
Authors: Xu Xiaolu , Zhang Deyong , Zhang Wuchun
Published: January 2020

TCS has been detected in water systems and organisms all over the world. TCS in water body mostly exists at ng/L or g/L level. The highest content of TCS is mostly from sewage plant water samples, some of which reach 26.80 g/L. TCS concentration was 0.4-38.0 ng/g in maternal plasma and 0.022-0.95 ng/g in breast milk. TCS has been proved to be toxic to algae, plants, lower animals, amphibians, fish, mammals and other organisms at all levels, mainly in growth inhibition, lethal effect, endocrine interference, reproductive toxicity, DNA toxicity and so on.
Design of A New High Efficiency Heat Storage System for Small and Medium-sized Photothermal Power Stations
Authors: Wang Yipu , Wang Bingzheng
Published: January 2020

In order to solve the problems of low temperature and high cost of traditional photothermal power generation heat storage system, a new high-temperature solid heat storage system consisting of three subsystems of heat extraction, heat storage and heat utilization is designed. Taking air as heat medium and safe heat-resisting regenerator as heat storage material, the heat preservation characteristics, overall thermal efficiency and flow resistance of the regenerator were analyzed and calculated. The results show that the regenerative system runs steadily, the heat loss of the regenerator is less than 5%, and the overall thermal efficiency of the system is more than 85%, which is better than the general regenerative system.
The Co-Pilot Position of Vehicle Noise Quality Prediction Based on SVM
Authors: Zhang Xiaojuan
Published: January 2020

In three different types of domestic cars for example, the paper studied interior noise sound quality when engine idle at a constant speed in different speed operation. Noise test using HEAD Acoustics multi-channel noise test system, sound quality subjective evaluation experiment was carried out in a semi-anechoic. Vehicle sound quality was studied using support vector machine (SVM) model, the results showed that car interior sound quality mainly by four psycho-acoustical parameters: A-weighted sound pressure level, loudness, roughness and jitter degree. The support vector machine forecasting method can guarantee the accuracy of prediction results for small sample data, which has higher accuracy in predicting, error lower.
Wet Oxidation Treatment of Waste Activated Sludge of a Pharmaceutical Factory
Authors: Guo Pengfei , Zeng Xu , Yao Guodong , Zhou Yangyuan , Zhao Jianfu
Published: January 2020

As the development of pharmaceutical industry, large amounts of sludge was produced, which is a hazardous waste with high environmental risks and high disposal fees. In this study, the wet oxidation treatment of pharmaceutical sludge was investigated. The effects of the reaction parameters on the process performance were discussed, such as reaction time, temperature, initial oxygen supply and catalysts. The results illustrated that the highest removal rate of volatile suspended solids (VSS) and the total chemical oxygen demand (COD) removal rates could reach up to 60.7% and 91.3% separately under 260°C with initial oxygen pressure 1.0 MPa and the reaction time 60 min. Thus, the wet oxidation process provides an economical and feasible alternative for the industrial activated sludge treatment, especially for the pharmaceutical sludge.
Analysis of Removal Function Results of Permanent Magnet Polishing Device Test
Authors: Zhou Xiaoqin , Sun Baoquan , Wang Haocheng , Yu Hang , Wu Xiaoyang
Published: January 2020

Based on the test platform of the polishing device, the material removal function model of the workpiece is obtained by using the Preston empirical equation and the motion state of the polishing tool. The test platform is built and the material removal model is verified by polishing the workpiece. Using Matlab software, draw the mathematical model material removal function curve and the test material removal function curve, analyze and compare the material removal law of the workpiece, and analyze the surface quality before and after the workpiece polishing.
Characteristics of the Violent Typhoon Events Seriously Affecting Hainan Island and Its Relationship with PDO
Authors: Zhu Jingjing , Zhao Xiaoping , Wu Shengan , Xing Caiying , Yang Jing
Published: January 2020

With the typhoon cyclone data, NCEP/NCAR reanalysis datasets and PDO index data from 1949 to 2018, the characteristics of violent typhoon events seriously affecting Hainan Island (VTESAHs for short) in the past 70 years are analyzed. On this basis, the characteristics of VTESAHs in the different phases of PDO and their relationship with SST are analyzed. The results show that there is obvious inter-annual variation in the frequency of VTESAHs. The VTESAHs have good continuity in both calm and active periods, and have obvious clustering. VTESAHs are more likely to occur in the cold phase years of PDO, almost generated in the western Pacific. The source of VTESAHs in the cold phase years of PDO are mainly concentrated in the sea area of 5 °N -15°N and 125 °E -150°E, while the source of VTESAHs in the warm phase years of PDO are mainly around 10°N. When the PDO phase is cold (warm), there is a significant negative (positive) correlation between the frequency of VTESAHs and the sea surface temperature in the western Pacific Ocean east of the Philippines at low latitudes.