High solid content 45S5 bioglass®-based scaffolds using stereolithographic ceramic manufacturing: process, structural and mechanical properties

Zhiyong Ma,Jun Xie,Xian Zhen Shan,Jiabin Zhang,Qifan Wang 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.2

45S5 Bioglass® has been widely used in bone tissue engineering scaffold due to its high bioactive properties. 3D printing method is a popular way to fabricate scaffolds. The extrusion printing method causes poor shape and dimensional accuracy of the scaffolds. The ordinary light-cured 3D printing method leads to low solid content of the scaffolds, which causes large shape shrinkages and low mechanical properties after sintering. In this study, we employed the stereolithographic ceramic manufacturing (SLCM) method to fabricate 45S5 Bioglass®-based scaffolds. Coating-then-stereolithographic layer by layer is the core process of SLCM method. Based on the optimization of the parameters of SLCM process and sintering process, the solid content of the 45S5 scaffold can be improved to a maximum of 70 %, and the linear shrinkage and compressive strength were effectively improved. The proposed method can be used not only for fabricating bone tissue engineering scaffold, but also for manufacturing other high solid content ceramic products.

An Improved Eclat Algorithm for Mining Association Rules Based on Increased Search Strategy

Zhiyong Ma,Juncheng Yang,Taixia Zhang,Fan Liu 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.5

Although Eclat algorithm is an efficient algorithm for mining association rules, there are some disadvantages which limit the efficient of Eclat. In this paper, we proposed an improved Eclat algorithm called Eclat_growth which is based on the increased search strategy. There are three main steps in the Eclat_growth algorithm. First, it scans the database and stores it into a table using vertical data format. Then, it builds an increased two-dimensional pattern tree and the TID_sets of itemsets in the vertical data format table are added into the pattern tree row by row. New frequent itemsets are generated by combining the new added item data with the existing frequent itemsets in the pattern tree. Finally, all frequent itemsets can be found by picking up all nodes of the pattern tree. In the process of generating new frequent itemsets, the prior knowledge is used to fully clip the candidate itemsets. In the process of generating an intersection of two itemsets and calculating the support degree, we proposed a new method called BSRI (Boolean array setting and retrieval by indexes of transactions) to reduce the run time. By comparing Eclat_growth with Eclat, Eclat-diffsets, Eclat-opt and hEclat, it is indicated that Eclat_growth has the highest performance in mining associating rules from various databases.

Effects of manufacturing process and surface treatments on mechanical properties of PLA/SCF composites using extrusion printing

Zhiyong Ma,Zheng Qian,Jiabin Cai 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5

Short carbon fiber (SCF) reinforced polylactic acid (PLA) composites were fabricated by extrusion printing, and the effects of process parameters and surface treatments on the mechanical properties of composites were studied. Based on the rheological properties of composites and the extrusion process simulation, pure PLA specimens and PLA/SCF specimens were manufactured under different printing parameters. Three kinds of surface treatment were adopted to improve the mechanical properties. The experimental results show that SCF can effectively improve the tensile strength and bending strength, but the compressive strength decreased. The specimen had the best mechanical properties when the layer height was 0.1 mm and the nozzle diameter was 0.6 mm. The mechanical properties can be further improved by coupling agent coating method, and the compressive strength was even higher than that of pure PLA specimen. The research in this paper can provide a reference for the fabrication of thermoplastic composites with excellent mechanical properties by extrusion printing.

Numerical simulation study of the Reynolds number effect on two bridge decks based on the deterministic vortex method

Zhiyong Zhou,Rujin Ma 한국풍공학회 2010 Wind and Structures, An International Journal (WAS Vol.13 No.4

Researches on the Reynolds number effect on bridge decks have made slow progress due to the complicated nature of the subject. Heretofore, few studies on this topic have been made. In this paper, aerostatic coefficients, Strouhal number (St), pressure distribution and Reynolds number (Re) of Great Belt East Bridge and Sutong Bridge were investigated based on deterministic vortex method (DVM). In this method, Particle Strength Exchange (PSE) was chosen to implement the simulation of the flow around bluff body and to analyze the micro-mechanism of the aerostatic loading and Reynolds number effect. Compared with the results obtained from wind tunnel tests, reliability of numerical simulation can be proved. Numerical results also showed that the Reynolds number effect on aerostatic coefficients and Strouhal number of the two bridges can not be neglected. In the range of the Reynolds number from 105 to 106, it has great effect on the Strouhal number of Sutong Bridge, while the St is difficult to obtain from wind tunnel tests in this range.

Effects of the Microstructure of Copper Through-Silicon Vias on their Thermally Induced Linear Elastic Mechanical Behavior

ZhiYong Wu,Zhiheng Huang,Yucheng Ma,Hua Xiong,Paul P. Conway 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.1

Through-silicon vias (TSVs) have been investigated extensively in recent years. However, the physical mechanisms behind some of the common problems associated with TSVs, such as the protrusion of Cu vias, are still unknown. In addition, since the dimensions of TSVs have been shrunk to microscopic levels, the sizes of the microstructural features of TSVs are no longer small compared to the dimensions of the vias. Therefore, the role and importance of the microstructural features of TSVs need to be studied to enable more accurate reliability predictions. This study focused on the effects the microstructural features of TSVs, i.e., the Cu grains and their [111] texture, grain size distribution, and morphology, have on the thermally induced linear elastic behavior of the vias. The results of the study indicate that stress distribution in the model that takes into account the Cu grains, whose Young’s moduli and Poisson’s ratios are set according to their crystallographic orientations, is more heterogeneous than that in a reference model in which the bulk properties of Cu are used. Stresses as high as 250 MPa are observed in the via of the model that takes into consideration the Cu grains, while stresses in the via of the reference model are all lower than 150 MPa. In addition, smaller Cu grains in the vias result in higher stresses; however, the variation in stress owning to changes in the grain size is within 20 MPa. The frequency of the stresses ranging from 80 MPa to 100 MPa was the highest in the stress distribution of the vias, depending on boundary conditions. The stress level in the vias decreases with the decrease in the number of grains with the [111] texture. Finally, the stress level is lower in the model in which the grain structure is generated using a phase field model and is closer to that of the microstructures present in real materials.

Numerical simulation study of the Reynolds number effect on two bridge decks based on the deterministic vortex method

Zhou, Zhiyong,Ma, Rujin Techno-Press 2010 Wind and Structures, An International Journal (WAS Vol.13 No.4

Researches on the Reynolds number effect on bridge decks have made slow progress due to the complicated nature of the subject. Heretofore, few studies on this topic have been made. In this paper, aerostatic coefficients, Strouhal number ($S_t$), pressure distribution and Reynolds number ($R_e$) of Great Belt East Bridge and Sutong Bridge were investigated based on deterministic vortex method (DVM). In this method, Particle Strength Exchange (PSE) was chosen to implement the simulation of the flow around bluff body and to analyze the micro-mechanism of the aerostatic loading and Reynolds number effect. Compared with the results obtained from wind tunnel tests, reliability of numerical simulation can be proved. Numerical results also showed that the Reynolds number effect on aerostatic coefficients and Strouhal number of the two bridges can not be neglected. In the range of the Reynolds number from $10^5$ to $10^6$, it has great effect on the Strouhal number of Sutong Bridge, while the St is difficult to obtain from wind tunnel tests in this range.

Rapid Separation of Gossypol from Cottonseeds by a Solid-Phase Synthetic Method

Hankui Wu,Zhiyong Xu,Ya Ma,He Qi,Jinxia Cao,Gang Li,Yong Chen,Weihua Yang 대한화학회 2016 대한화학회지 Vol.60 No.3

Rapid Separation of Gossypol from Cottonseeds by a Solid-Phase Synthetic Method

Wu, Hankui,Xu, Zhiyong,Ma, Ya,Qi, He,Cao, Jinxia,Li, Gang,Chen, Yong,Yang, Weihua Korean Chemical Society 2016 대한화학회지 Vol.60 No.3

Power control of CiADS core with the intensity of the proton beam

Kai Yin,Wenjing Ma,Wenjuan Cui,Zhiyong He,Xinxin Li,Shiwu Dang,Feng Yang,Yuhui Guo,Limin Duan,Meng Li,Yikai Hou 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.4

This paper reports the control method for the core power of the China initiative Accelerator DrivenSystem (CiADS) facility. In the CiADS facility, an intense external neutron source provided by a protonaccelerator coupled to a spallation target is used to drive a sub-critical reactor. Without any control rodinside the sub-critical reactor, the core power is controlled by adjusting the proton beam intensity. Inorder to continuously change the beam intensity, an adjustable aperture is considered to be used at theLow Energy Beam Transport (LEBT) line of the accelerator. The aperture size is adjusted based on theProportional Integral Derivative (PID) controllers, by comparing either the setting beam intensity or thesetting core power with the measured value. To evaluate the proposed control method, a CiADS coremodel is built based on the point reactor kinetics model with six delayed neutron groups. The simulations based on the CiADS core model have indicated that the core power can be controlled stably byadjusting the aperture size. The response time in the adjustment of the core power depends mainly onthe adjustment time of the beam intensity

Investigation on aerodynamic instability of high-voltage transmission lines under rain-wind condition

Chao Zhou,Yibing Liu,Zhiyong Ma 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.1

Under rain-wind conditions, rain-wind induced aerodynamic instability phenomenon often occurs on high-voltage transmission lines. Like the effects of any other oscillations, this kind of vibration intensifies the fatigue of high-voltage conductors, especially on line supportsor clamps. The presence of raindrops and wind associated with electric field maybe the main cause of this phenomenon. On rainydays, raindrops hit the transmission line and suspends to the high-voltage conductor. The suspended raindrops form upper rivulet andlower rivulet and take an elliptical arch shape along the surface of the high-voltage conductor by action of the wind, if rainfall is sufficient. Moreover, the rivulets are enlarged as a cone shape with the electric field of high-voltage conductor. The upper rivulet’s effect onthe original cross-section formation of the high-voltage conductor and its movement are likely to be the cause of aerodynamic instability. The objective of this paper is to validate a two-dimensional model to investigate the effects of different parameters (electric field strength,wind velocity, frequency and damping ratio of the dynamic system) on aerodynamic stability of the conductor. The Lyapunov stabilitytheory is applied to the model to derive the criterion for the instable angle of the rivulet. Moreover, an experimental conductor modelwith a moveable artificial upper rivulet is set-up and tested in a wind tunnel. The theoretical results are in good agreement with the experimentaldata. The model enable better comprehension of the rain-wind induced aerodynamic instability on the conductor.