Fabrication, design, and optimization of hierarchical composite Kagome honeycomb sandwich structure under uniaxial compression

Song Shijun,Xiong Chao,Yin Junhui,Yang Zhaoshu,Wang Lu 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.2

In this study, a hierarchical composite Kagome honeycomb sandwich (HCKHS) structure was manufactured based on the interlocking method, and its uniaxial compression performance was explored. Through experiments, the compressive strength, stiffness, energy absorption, and failure process of HCKHS specimens of seven different sizes were determined and compared. Mechanical analytical models were established, and the variation trend in the specific strength was predicted and compared with those of other advanced sandwich structures. The size effect of the HCKHS specimens was analyzed. The influence of a single variable on the core modulus, failure strength, and failure modes was discussed, and failure mechanism maps were drawn. The structure was optimized based on the maximum specific strength and engineering application, and the optimal size design ratio was obtained. The results showed that the HCKHS specimens exhibited excellent compressive properties with a convenient manufacturing process, making them suitable for lightweight applications in engineering. The optimization ideas presented herein are also applicable to other two-dimensional hierarchical or normal composite honeycomb sandwich structures with diamond, triangular, and hexagonal shapes.

Excellent Strengthening of Low-Carbon Steel by Severe Free-End Torsion

Shijun Tan,Bo Song,Hongbing Chen,Xiaodong Tan,Risheng Qiu,Tingting Liu,Ning Guo,Shengfeng Guo 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.8

In this work, the effects of free-end torsion on microstructure and tensile property of low-carbon steel were investigated indetail. Low-carbon steels exhibited exceptionally high yield strength through severe torsion deformation. Such high hardeningeffect was mainly attributed to the severe lattice distortion, high density of dislocations and the change in grain shape. Moreover, a gradient deformation structure can be introduced by torsion deformation. The gradient-structure can generate ahigh hetero-deformation induced strengthening, which can increase the strain hardening capacity and remain high plasticity/toughness. Therefore, with increasing torsion angle from 700 to 2800 deg., the uniform elongation and the peak strength werelargely enhanced. After twisting 2800 deg., yield strength and peak strength can achieve 524 MPa and 675 MPa, respectively,and good tensile elongations (εf = 9.6%, εu = 7.4%) are remained.

An Innovative Training Program on Engineering Education

Juncai Sun,Song Li,Shijun Ji 한국공학교육학회 2014 공학교육연구 Vol.17 No.4

From 2010, an “excellent engineer” undergraduate and graduate program had been initiated in higher education of China to promote thedevelopment of industry and social economy. In this circumstance, the engineering education programs in Dalian Maritime Universityare reformed to satisfy the requirements of transportation industries. And the engineering practice, engineering activities, and engineeringcourses are emphasized. In this training program, industrial communities are deeply involved in the engineering education and trainingprocedure; the students are educated and trained in university and enterprise according to the common standards and industrial standards;and the engineering competences and creative ability are emphasized and are to be enhanced in the training schedules and procedure. A joint-training mode has been established already between Dalian Maritime University and enterprises in transportation fields.

A Duplex PCR Assay for Rapid Detection of Phytophthora nicotianae and Thielaviopsis basicola

Na Liu,Shijun Jiang,Songli Feng,Wenyan Shang,Guozhen Xing,Rui Qiu,Chengjun Li,Shujun Li,Wenming Zheng 한국식물병리학회 2019 Plant Pathology Journal Vol.35 No.2

A duplex PCR method was developed for simultaneous detection and identification of tobacco root rot pathogens Phytophthora nicotianae and Thielaviopsis basicola. The specific primers for P. nicotianae were developed based on its internal transcribed spacer (ITS) regions of ribosomal gene, ras gene and hgd gene, while the specific primers for T. basicola were designed based on its ITS regions and β-tubulin gene. The specificity of the primers was determined using isolates of P. nicotianae, T. basicola and control samples. The results showed that the target pathogens could be detected from diseased tobacco plants by a combination of the specific primers. The sensitivity limitation was 100 fg/μl of pure genomic DNA of the pathogens. This new assay can be applied to screen out target pathogens rapidly and reliably in one PCR and will be an important tool for the identification and precise early prediction of these two destructive diseases of tobacco.

Cathode Materials LaNi1−xCuxO3 for Low Temperature Solid Oxide Fuel Cells

Juncai Sun,Chengli Wang,Song Li,Shijun Ji 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.12

New cathode materials LaNi1−xCuxO3 (typically LaNi0.8Cu0.2O3) were synthesized using a co-precipitation method. The structure and morphology of the powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The composite material [Ce0.8Sm0.2O2-ä(SDC) and carbonate (Na2CO3,Li2CO3)], NiO and LaNi1−xCuxO3 were used as the electrolyte, anode and cathode, respectively. The electrochemical performance of La-Ni-Cu-O perovskite oxide at low temperatures (400~550oC) was studied. The results showed that LaNi0.8Cu0.2O3 precursor powder prepared through a co-precipitation method and calcined at 860oC for 2 h formed uniform grains with diameters in the range of 400~500 nm. The maximum power density and the short circuit current density of the single cell unit at 550oC were found to be 390 mW/cm2 and 968 mA/cm2, respectively. New cathode materials LaNi1−xCuxO3 (typically LaNi0.8Cu0.2O3) were synthesized using a co-precipitation method. The structure and morphology of the powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The composite material [Ce0.8Sm0.2O2-ä(SDC) and carbonate (Na2CO3,Li2CO3)], NiO and LaNi1−xCuxO3 were used as the electrolyte, anode and cathode, respectively. The electrochemical performance of La-Ni-Cu-O perovskite oxide at low temperatures (400~550oC) was studied. The results showed that LaNi0.8Cu0.2O3 precursor powder prepared through a co-precipitation method and calcined at 860oC for 2 h formed uniform grains with diameters in the range of 400~500 nm. The maximum power density and the short circuit current density of the single cell unit at 550oC were found to be 390 mW/cm2 and 968 mA/cm2, respectively.

Investigation of the origin of abnormal grain growth in the sintering process of Sr0.5Ba0.5Nb2O6 ceramics without eutectic liquid-phase

Sui Wanmei,Luan Shijun,Song Ranran,Wang Chunlong 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.6

Abnormal grain growth in the traditional sintering process of (SrxBax−1)Nb2O6 limites its application and the localized liquidphase exsisting is regarded the main reason for the presence of abnormal grain growth. To prevent the presence of a localized liquid-phase, the sol-gel method was employed to synthesize nano-sized powders of Sr0.5Ba0.5Nb2O6, which was followed by a pure solid-phase sintering process of nano-sized powders to observe the evolution of the grain morphology. SEM observation revealed that the abnormal and preferential rod-like grain growth along the c-axis existed in the pure state-phase sintering for the Sr0.5Ba0.5Nb2O6 material companied with some of the smaller grains being diminished or consumed. This behavior would exist in the traditional solid-phase sintering with or without the localized liquid-phase. This would be another important factor to aid the abnormal grain growth and should be prevented in the manufacturing process. The effects of grain sizes on the dielectric constant, Tc and diffuse phase transion (DPT) were observed in the Sr0.5Ba0.5Nb2O6 ceramics.

A Duplex PCR Assay for Rapid Detection of Phytophthora nicotianae and Thielaviopsis basicola

Liu, Na,Jiang, Shijun,Feng, Songli,Shang, Wenyan,Xing, Guozhen,Qiu, Rui,Li, Chengjun,Li, Shujun,Zheng, Wenming The Korean Society of Plant Pathology 2019 Plant Pathology Journal Vol.35 No.2

A duplex PCR method was developed for simultaneous detection and identification of tobacco root rot pathogens Phytophthora nicotianae and Thielaviopsis basicola. The specific primers for P. nicotianae were developed based on its internal transcribed spacer (ITS) regions of ribosomal gene, ras gene and hgd gene, while the specific primers for T. basicola were designed based on its ITS regions and ${\beta}$-tubulin gene. The specificity of the primers was determined using isolates of P. nicotianae, T. basicola and control samples. The results showed that the target pathogens could be detected from diseased tobacco plants by a combination of the specific primers. The sensitivity limitation was $100fg/{\mu}l$ of pure genomic DNA of the pathogens. This new assay can be applied to screen out target pathogens rapidly and reliably in one PCR and will be an important tool for the identification and precise early prediction of these two destructive diseases of tobacco.

An Innovative Training Program on Engineering Education

Sun, Juncai,Li, Song,Ji, Shijun Korean Society for Engineering Education 2014 공학교육연구 Vol.17 No.4

From 2010, an "excellent engineer" undergraduate and graduate program had been initiated in higher education of China to promote the development of industry and social economy. In this circumstance, the engineering education programs in Dalian Maritime University are reformed to satisfy the requirements of transportation industries. And the engineering practice, engineering activities, and engineering courses are emphasized. In this training program, industrial communities are deeply involved in the engineering education and training procedure; the students are educated and trained in university and enterprise according to the common standards and industrial standards; and the engineering competences and creative ability are emphasized and are to be enhanced in the training schedules and procedure. A joint-training mode has been established already between Dalian Maritime University and enterprises in transportation fields.

Cathode Materials LaNi_1−xCu_xO₃ for Low Temperature Solid Oxide Fuel Cells

Sun, Juncai,Wang, Chengli,Li, Song,Ji, Shijun The Korean Ceramic Society 2008 한국세라믹학회지 Vol.45 No.12

New cathode materials $LaNi_{1-x}{Cu_x}{O_3}$ (typically $LaNi_{0.8}Cu_{0.2}O_3$) were synthesized using a co-precipitation method. The structure and morphology of the powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The composite material [$Ce_{0.8}Sm_{0.2}O_{2-\ddot{a}}$(SDC) and carbonate (${Na_2}{CO_3},{Li_2}{CO_3}$)], NiO and $LaNi_{1-x}{Cu_x}{O_3}$ were used as the electrolyte, anode and cathode, respectively. The electrochemical performance of La-Ni-Cu-O perovskite oxide at low temperatures ($400{\sim}550^{\circ}C$) was studied. The results showed that $LaNi_{0.8}Cu_{0.2}O_3$ precursor powder prepared through a co-precipitation method and calcined at $860^{\circ}C$ for 2 h formed uniform grains with diameters in the range of $400{\sim}500\;nm$. The maximum power density and the short circuit current density of the single cell unit at $550^{\circ}C$ were found to be $390\;mW/cm^2$ and $968\;mA/cm^2$, respectively.

Formation Mechanisms of the Extreme Rainfall and Mesoscale Convective Systems over South China during the Dragon Boat Rainy Season of 2022

Fu Yanan,선진화,Wu Zhifang,Chen Tao,Song Xiaodong,Sun Shijun,Fu Shenming 한국기상학회 2024 Asia-Pacific Journal of Atmospheric Sciences Vol.60 No.4

The formation mechanisms of the record-breaking rainfall event during the Dragon Boat Rainy Season (DBRS) of 2022 are comprehensively analyzed from the synoptic scale and the mesoscale perspectives. The extreme rainfall event is characterized by the highest rainfall amount since 1981, and an abnormal spatial distribution with much higher (lower) rainfall amount in the northern (southern) part of South China. The abnormal circulation and thermodynamic conditions are mainly responsible for the extreme rainfall. The favorite synoptic condition for rainfall is the combination of warm advection, frontal forcing, orographic lifting and low-level jet favor the convection development. The similar configurations repeatedly impact South China during the DBRS of 2022, causing multiple heavy rainfall events, leading to the extreme rainfall of the whole period. The abnormal moisture convergence together with the frontal zone, which is stronger than the climatology, results in the rainfall centers over the northern part of South China. 54.35% of the rainfall amount is related to mesoscale convective systems (MCSs) which mainly originate from four regions. The MCSs from the four regions are characterized by different formation peaks, spatial scales, lifetimes and propagations. The large-scale warm and moist air mass, the moistening caused by synoptic advection and the local diabatic heating are responsible for the increasing instability for the MCSs. The low-level jets play an important role in the formation of MCSs by providing moisture. The thermodynamic (dynamic) environmental conditions control the formation of MCSs in the afternoon (night).