Experimental Investigation on the Properties of Sustainable Pervious Concrete with Different Aggregate Gradation

Junyu Zhang,Haoran Sun,Xiaotian Shui,Wenxuan Chen 한국콘크리트학회 2024 International Journal of Concrete Structures and M Vol.18 No.2

Pervious concrete (PC) as a green infrastructure material has been increasingly used due to its positive environmental impacts, such as controlling storm water runoff, removing water pollutants and reducing heat island effect. The aggregate gradation is a critical factor influencing the physical properties of PC. Therefore, this paper represents an attempt to determine the effects of aggregate gradation on the various physical properties of PC, and then to explore relationships between them. To this end, three aggregate gradations 4.75–9.5 mm, 9.5–19 mm and 19–31.5 mm were recombined with various proportions (20–80%) to obtain five different gradations named as A, B, C, D and E. PC mixtures were prepared with these five aggregate gradations. Then, physical and mechanical properties of PC including porosity, permeability, compressive strength and water stability were investigated, according to the available specification. The results suggested that it was feasible to use waste concrete for permeable pavement, because all the specimens provided required specification requirements. Different linear relationships were also found between the maximum aggregate size and porosity, permeability coefficient, compressive strength and its loss rate. That is, porosity and permeability increased with the proportion of larger size aggregate increased, however, compressive strength reduced. Thus the compressive strength had an inverse correlation with the porosity and water permeability. Among five different aggregate gradations, group C (20% of 4.75–9.5 mm aggregate, 50% of 9.5–19 mm aggregate and 30% of 19–31.5 mm aggregate) can be seen as the optimum gradation and is suitable for base layer materials of permeable pavements.

Chitosan-based porous carbon as a support for Zn-based catalysts in acetylene acetoxylation

Junyu Zhang,Fulong Zhu,Ying Zhang,Mingyuan Zhu,Hongling Li,Bin Dai 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.7

Using the biomass material chitosan as a precursor and potassium citrate (PC) as a substitute for traditionalcorrosive activators such as KOH and ZnCl2, a chitosan-based porous carbon material with high specific surfacearea was successfully prepared and used as a support for the catalytic acetylene acetoxylation reaction. By controllingthe PC content and the calcination temperature, chitosan-based porous carbon with a suitable pore structure and abundantsurface oxygen functional groups was obtained. The inductively coupled plasma analysis confirmed that the zinccontent of the 0.9Zn/CS-PC1-800 catalyst was about 14 wt%, and the acetic acid conversion reached 81%. Furthermore,the scanning electron microscopy and Brunauer-Emmett-Teller (BET) analysis showed that the catalyst carrierwas mesoporous carbon material, and different PC content formed different pore size distribution at different calcinationtemperatures. In addition, X-ray photoelectron spectroscopy analysis demonstrated that the content of O in chitosan-based porous carbon was rich, and PC consumed the O content on the surface of carbon materials duringactivation. Because O content and pore size structure on carrier surface are closely related to acetic acid conversion,reasonable PC content and calcination temperature are very important for acetic acid conversion.

Study of Mechanism of Counter-rotating Turbine Increasing Two-Stage Turbine System Efficiency

Yanbin Liu,Yangjun Zhang,Weilin Zhuge,Xinqian Zheng,Shuyong Zhang,Junyue Zhang 한국유체기계학회 2013 International journal of fluid machinery and syste Vol.6 No.3

Two-stage turbocharging is an important way to raise engine power density, to realize energy saving and emission reducing. At present, turbine matching of two- stage turbocharger is based on MAP of turbine. The matching method does not take the effect of turbines' interaction into consideration, assuming that flow at high pressure turbine outlet and low pressure turbine inlet is uniform. Actually, there is swirl flow at outlet of high pressure turbine, and the swirl flow will influence performance of low pressure turbine which influencing performance of engine further. Three-dimension models of turbines with two-stage turbocharger were built in this paper. Based on the turbine models, mechanism of swirl flow at high pressure turbine outlet influencing low pressure turbine performance was studied and a two-stage radial counter-rotation turbine system was raised. Mechanisms of the influence of counter-rotation turbine system acting on low-pressure turbine were studied using simulation method. The research result proved that in condition of small turbine flow rate corresponding to engine low-speed working condition, counter-rotation turbine system can effectively decrease the influence of swirl flow at high pressure turbine outlet imposing on low pressure turbine and increases efficiency of the low-pressure turbine, furthermore increases the low-speed performance of the engine.

Study of Mechanism of Counter-rotating Turbine Increasing Two-Stage Turbine System Efficiency

Liu, Yanbin,Zhuge, Weilin,Zheng, Xinqian,Zhang, Yangjun,Zhang, Shuyong,Zhang, Junyue Korean Society for Fluid machinery 2013 International journal of fluid machinery and syste Vol.6 No.3

Two-stage turbocharging is an important way to raise engine power density, to realize energy saving and emission reducing. At present, turbine matching of two-stage turbocharger is based on MAP of turbine. The matching method does not take the effect of turbines' interaction into consideration, assuming that flow at high pressure turbine outlet and low pressure turbine inlet is uniform. Actually, there is swirl flow at outlet of high pressure turbine, and the swirl flow will influence performance of low pressure turbine which influencing performance of engine further. Three-dimension models of turbines with two-stage turbocharger were built in this paper. Based on the turbine models, mechanism of swirl flow at high pressure turbine outlet influencing low pressure turbine performance was studied and a two-stage radial counter-rotation turbine system was raised. Mechanisms of the influence of counter-rotation turbine system acting on low-pressure turbine were studied using simulation method. The research result proved that in condition of small turbine flow rate corresponding to engine low-speed working condition, counter-rotation turbine system can effectively decrease the influence of swirl flow at high pressure turbine outlet imposing on low pressure turbine and increases efficiency of the low-pressure turbine, furthermore increases the low-speed performance of the engine.

Mesoscale model for cracking of concrete cover induced by reinforcement corrosion

Junyu Chen,Weiping Zhang,Xianglin Gu 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.22 No.1

Cracking of concrete cover induced by reinforcement corrosion is a critical issue for life-cycle design and maintenance of reinforced concrete structures. However, the critical degree of corrosion, based on when the concrete surface cracks, is usually hard to predict accurately due to the heterogeneity inherent in concrete. To investigate the influence of concrete heterogeneity, a modified rigid-body-spring model, which could generate concrete sections with randomly distributed coarse aggregates, has been developed to study the corrosion-induced cracking process of the concrete cover and the corresponding critical degree of corrosion. In this model, concrete is assumed to be a three-phase composite composed of coarse aggregate, mortar and an interfacial transition zone (ITZ), and the uniform corrosion of a steel bar is simulated by applying uniform radial displacement. Once the relationship between radial displacement and degree of corrosion is derived, the critical degree of corrosion can be obtained. The mesoscale model demonstrated its validity as it predicted the critical degree of corrosion and cracking patterns in good agreement with analytical solutions and experimental results. The model demonstrates how the random distribution of coarse aggregate results in a variation of critical degrees of corrosion, which follows a normal distribution. A parametric study was conducted, which indicates that both the mean and variation of critical degree of corrosion increased with the increase of concrete cover thickness, coarse aggregates volume fraction and decrease of coarse aggregate size. In addition, as tensile strength of concrete increased, the average critical degree of corrosion increased while its variation almost remained unchanged.

The Morphological Evaluation of the Cervical Muscle in Patients With Basilar Invagination: A Magnetic Resonance Imaging-Based Study

Junyu Lin,Panjie Xu,Jianying Zheng,Zhang Zefan,Jingwen Tan,Hang Xiao,Siyan Yu,Qingan Zhu,Wei Ji 대한척추신경외과학회 2023 Neurospine Vol.20 No.3

Objective: To investigate the characteristics of functional muscle and muscle size in patients with basilar invagination (BI) and explore the effects of atlantoaxial dislocation. Methods: Eighty BI patients (BI group) and 80 age- and sex-matched asymptomatic people (control group) were included. Axial T2 magnetic resonance imaging image was used to measure the cross-sectional area (CSA) and functional CSA (FCSA). The sternocleidomastoid (SCM), longus capitis and longus colli (LCap & LC), trapezius (Trap), splenius capitis (SpCap), splenius cervicis (SpC), semispinalis capitis (SSCap), semispinalis cervicis (SSC), multifidus (MS), levator scapulae (LS) and posterior deep layer muscles (PDLM) were evaluated. Correlations between age, atlantodental interval (ADI), Chamberlain distance and muscles were observed. Results: BI group (39.4 ± 18.4 years; 33 males/47 females) exhibited significantly lower FCSA/CSA ratios than the control group in all extensor and flexor muscles, and presented smaller CSAs on the right and left Trap, SSC, LS, SCM, and left LCap & LC. FCSA/CSA ratios were significantly lower in BI patients with dislocation on the right Trap, SpCap, SpC, SSCap, MS, LS, LCap & LC, and PDLM, and the left SSCap, MS, and LCap & LC than in patients without deformity. Additionally, functional muscles of all parameters decreased with age in BI patients. Excluding children, the Trap, SpC, MS, and LS muscle sizes of BI patients tended to increase with age. ADI and Chamberlain distance tended to correlate negatively with FCSA/CSA ratio. Conclusion: The BI patients, especially those with atlantoaxial dislocation, had less functional muscles compared with the control group. Moreover, their functional muscles decreased with age more obviously.

Dead-Time for Zero-Voltage-Switching in Battery Chargers with the Phase-Shifted Full-Bridge Topology: Comprehensive Theoretical Analysis and Experimental Verification

Zhang, Taizhi,Fu, Junyu,Qian, Qinsong,Sun, Weifeng,Lu, Shengli The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

This paper presents a comprehensive theoretical analysis and an accurate calculation method of the dead-time required to achieve zero-voltage-switching (ZVS) in a battery charger with the phase-shifted full-bridge (PSFB) topology. Compared to previous studies, this is the first time that the effects of nonlinear output filter inductance, varied Miller Plateau length, and blocking capacitors have been considered. It has been found that the output filter inductance and the Miller Plateau have a significant influence on the dead-time for ZVS when the load current varies a lot in battery charger applications. In addition, the blocking capacitor, which is widely used to prevent saturation, reduces the circulating current and consequently affects the setting of the dead-time. In consideration of these effects, accurate analytical equations of the dead-time range for ZVS are deduced. Experimental results from a 1.5kW PSFB battery charger prototype shows that, with the proposed analysis, an optimal dead-time can be selected to meet the specific requirements of a system while achieving ZVS over wide load range.

Dead-Time for Zero-Voltage-Switching in Battery Chargers with the Phase-Shifted Full-Bridge Topology

Taizhi Zhang,Junyu Fu,Qinsong Qian,Weifeng Sun,Shengli Lu 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

This paper presents a comprehensive theoretical analysis and an accurate calculation method of the dead-time required to achieve zero-voltage-switching (ZVS) in a battery charger with the phase-shifted full-bridge (PSFB) topology. Compared to previous studies, this is the first time that the effects of nonlinear output filter inductance, varied Miller Plateau length, and blocking capacitors have been considered. It has been found that the output filter inductance and the Miller Plateau have a significant influence on the dead-time for ZVS when the load current varies a lot in battery charger applications. In addition, the blocking capacitor, which is widely used to prevent saturation, reduces the circulating current and consequently affects the setting of the dead-time. In consideration of these effects, accurate analytical equations of the dead-time range for ZVS are deduced. Experimental results from a 1.5kW PSFB battery charger prototype shows that, with the proposed analysis, an optimal dead-time can be selected to meet the specific requirements of a system while achieving ZVS over wide load range.

In vitro differentiation of spermatogonial stem cells using testicular cells from Guangxi Bama mini-pig

Huimin Zhao,Junyu Nie,Xiangxing Zhu,Yangqing Lu,Xingwei Liang,Huiyan Xu,Xiaogan Yang,Yunkai Zhang,Kehuan Lu,Shengsheng Lu 대한수의학회 2018 Journal of Veterinary Science Vol.19 No.5

In this study, we attempted to establish a culture system for in vitro spermatogenesis from spermatogonial stem cells (SSCs) of Bama mini-pig. Dissociated testicular cells from 1-month-old pigs were co-cultured to mimic in vivo spermatogenesis. The testicular cells were seeded in minimum essential medium alpha (a-MEM) supplemented with Knockout serum replacement (KSR). Three-dimensional colonies formed after 10 days of culture. The colonies showed positive staining for SSC-associated markers such as UCHL1, PLZF, THY1, OCT4, Dolichos biflorus agglutinin, and alkaline phosphatase. Induction of SSCs was performed in a-MEM + KSR supplemented with retinoic acid, bone morphogenetic protein 4, activin A, follicle-stimulating hormone, or testosterone. The results showed that STRA8, DMC1, PRM1, and TNP1 were upregulated significantly in the colonies after induction compared to that in testis from 1-month-old pigs, while expression levels of those genes were significantly low compared to those in 2-month-old testis. However, upregulation of ACROSIN was not significant. Replacement of a-MEM and KSR with Iscove’s modified Dulbecco’s medium and fetal bovine serum did not upregulate expression of these genes significantly. These results indicate that SSCs of Bama mini-pig could undergo differentiation and develop to a post-meiotic stage in α-MEM supplemented with KSR and induction factors.

Co-operative roles of IL-4Rα and IL-13Rα1 in the progression of ovarian carcinomas and the survival of ovarian carcinoma patients

( Won Ku Choi ),( Usama Khamis Hussein ),( Asmaa Gamal Ahmed ),( Junyue Zhang ),( Kyoung Min Kim ),( Ae Ri Ahn ),( Ho Sung Park ),( See-hyoung Park ),( Dong Hyu Cho ),( Kyu Yun Jang ) 대한산부인과학회 2023 대한산부인과학회 학술대회 Vol.109 No.-