An experimental investigation on the normal force behavior of magnetorheological suspensions

Guo, Chaoyang,Gong, Xinglong,Xuan, Shouhu,Zhang, Yanli,Jiang, Wanquan 한국유변학회 2012 Korea-Australia rheology journal Vol.24 No.3

In this work the normal force behavior of magnetorheological suspensions are systematically investigated. Four magnetorheological suspensions with different volume fractions (10%, 20%, 30%, and 40%) are prepared and both the static and dynamic normal forces of the samples are measured by using a commercial plate-plate magneto-rheometer under constant and sweeping magnetic field. A positive normal force will be generated when the applied magnetic field exceeds a critical value. The normal force firstly increases with the increasing of magnetic field strength and then reaches a saturation value. A magnetization model is utilized to represent this mechanism. The oscillatory dynamic normal forces with time are studied and their changes with shear rates are dependent on the volume fraction. Comparisons between static and dynamic normal forces show that the differences between them are dependent on the volume fraction and magnetic filed. The temperature effect on the normal force is studied and under high magnetic field the normal force would increase slightly with the increasing of temperature.

A comparison of the fracture resistances of endodontically treated mandibular premolars restored with endocrowns and glass fiber post-core retained conventional crowns

Guo, Jing,Wang, Zhiming,Li, Xuesheng,Sun, Chaoyang,Gao, Erdong,Li, Hongbo The Korean Academy of Prosthodonitics 2016 The Journal of Advanced Prosthodontics Vol.8 No.6

PURPOSE. This in-vitro study aimed to evaluate the fracture resistances and failure modes of endodontically treated mandibular premolars restored with endocrowns and conventional post-core retained crowns. MATERIALS AND METHODS. Thirty mandibular premolars were assigned into three groups (n=10): GI, intact teeth; GE, teeth with endocrowns; GC, teeth with conventional post-core supported crowns. Except for the teeth in group GI, all specimens were cut to 1.5 mm above the cementoenamel junction and endodontically treated. Both endocrowns and conventional crowns were fabricated from lithium-disilicate blocks using a CEREC 3D CAD/CAM unit. All specimens were subjected to thermocycling and then to $45^{\circ}$ oblique compressive load until fracture occurred. The fracture resistance and failure mode of each specimen were recorded. Data were analyzed with one-way ANOVA and LSD Post Hoc Test (${\alpha}=.05$). RESULTS. The fracture resistances of GE and GC were significantly lower than that of GI (P<.01), while no significant difference was found between GE and GC (P=.702). As of the failure mode, most of the specimens in GE and GC were unfavorable while a higher occurrence of favorable failure mode was presented in GI. CONCLUSION. For the restoration of mandibular premolar, endocrown shows no advantage in fracture resistance when compared with the conventional method. Both of the two methods cannot rehabilitate endodontically treated teeth with the same fracture resistances that intact mandibular premolars have.

A comparison of the fracture resistances of endodontically treated mandibular premolars restored with endocrowns and glass fiber postcore retained conventional crowns

Jing Guo,Zhiming Wang,Xuesheng Li,Chaoyang Sun,Erdong Gao,Hongbo Li 대한치과보철학회 2016 The Journal of Advanced Prosthodontics Vol.8 No.6

PURPOSE This in-vitro study aimed to evaluate the fracture resistances and failure modes of endodontically treated mandibular premolars restored with endocrowns and conventional post-core retained crowns. MATERIALS AND METHODS Thirty mandibular premolars were assigned into three groups (n=10): GI, intact teeth; GE, teeth with endocrowns; GC, teeth with conventional post-core supported crowns. Except for the teeth in group GI, all specimens were cut to 1.5 mm above the cementoenamel junction and endodontically treated. Both endocrowns and conventional crowns were fabricated from lithium-disilicate blocks using a CEREC 3D CAD/CAM unit. All specimens were subjected to thermocycling and then to 45° oblique compressive load until fracture occurred. The fracture resistance and failure mode of each specimen were recorded. Data were analyzed with one-way ANOVA and LSD Post Hoc Test (α=.05). RESULTS The fracture resistances of GE and GC were significantly lower than that of GI (P<.01), while no significant difference was found between GE and GC (P=.702). As of the failure mode, most of the specimens in GE and GC were unfavorable while a higher occurrence of favorable failure mode was presented in GI. CONCLUSION For the restoration of mandibular premolar, endocrown shows no advantage in fracture resistance when compared with the conventional method. Both of the two methods cannot rehabilitate endodontically treated teeth with the same fracture resistances that intact mandibular premolars have.

Research on optimization of milling performance of V-groove micro-texture ball-end milling cutter

Shucai Yang,Chaoyang Guo,Wei Ren 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.6

Titanium alloys generally have problems such as sticking, large cutting force, and poor heat dissipation during the cutting process., research shows that processing microtextures on the surface of the tool can effectively improve the above problems. Therefore, this paper designs the V-groove micro-textures based on the principle of bionics. Use simulation software to analyze the milling behavior of different V-groove micro-texture ball-end milling cutters for milling titanium alloys. Build a test platform to study the milling performance of the Vgroove micro-texture ball-end milling cutter for milling titanium alloys, obtain the prior choice range of V-groove micro-texture parameters, optimize the parameters based on the simulated annealing algorithm and conduct experimental verification. The results of the optimal tool parameters are that the opening angle of the V-groove micro-textures is 79°, the V-groove microtexture spacing is 170 μm, and the V-groove micro-texture width is 30 μm, the distance from blade of the V-groove micro-textures is 90 μm.

Contrast-enhanced ultrasonography-based renal blood perfusion in brain-dead donors predicts early graft function

Weiming He,Yuguang Xu,Chaoyang Gong,Xiaozhen Liu,Yuqiang Wu,Xi Xie,Jiazhen Chen,Yi Yu,Zhiyong Guo,Qiang Sun 대한초음파의학회 2023 ULTRASONOGRAPHY Vol.42 No.4

Purpose: The aim of this study was to quantify renal microcirculatory perfusion in braindead donors using contrast-enhanced ultrasonography (CEUS), and to establish an accurate, noninvasive, and convenient index for predicting delayed graft function (DGF) post-transplantation. Methods: In total, 90 brain-dead donor kidneys (training group, n=60; validation group, n=30) examined between August 2020 and November 2022 were recruited in this prospective study. CEUS was performed on the kidneys of brain-dead donors 24 hours before organ procurement and time-intensity curves were constructed. The main measures were arrival time, time to peak, and peak intensity of the kidney segmental arteries, cortex, and medulla. Recipients were divided into DGF and non-DGF groups according to early post-transplant graft function. The area under the receiver operating characteristic curve (AUC) was used to assess diagnostic performance. Results: The arrival time of the kidney segmental artery and cortex and the time interval between the time to peak of the segmental artery and cortex were identified as independent factors associated with DGF by multivariate stepwise regression analysis. A new index for the joint prediction model of three variables, the contrast-enhanced ultrasonography/Kidney Donor Profile index (CEUS-KDPI), was developed. CEUS-KDPI showed high accuracy for predicting DGF (training group: AUC, 0.91; sensitivity, 90.5%; specificity, 92.3%; validation group: AUC, 0.84; sensitivity, 75.0%; specificity, 92.3%). Conclusion: CEUS-KDPI accurately predicted DGF after kidney transplantation. CEUS may be a potential noninvasive tool for bedside examinations before organ procurement and may be used to predict early renal function after kidney transplants kidneys from donors after brain death.

World Health Organization survey on the level of integration of traditional Chinese medicine in Chinese health system rehabilitation services

Lei Fang,Ran-ran Zhu,Zhen Sang,Xiao-ting Xu,Lin-yun Zheng,Yanwei Xiang,Chaoyang Guo,Zhenrui Li,Stephane Alexandre Espinosa,Qi Zhang,Chunlei Shan 한국한의학연구원 2023 Integrative Medicine Research Vol.12 No.2

Background: To meet the growing global demand for rehabilitation services, the World Health Organization (WHO) launched Rehabilitation 2030. This study was commissioned by the WHO to investigate the integration degree of traditional Chinese medicine (TCM) in Chinese health system rehabilitation services and the demand for TCM rehabilitation in China. Methods: Twenty TCM rehabilitation experts and relevant government administrators were invited to complete the questionnaire between September 2019 and January 2022. The development of traditional, complementary, and integrative medicine (TCI) rehabilitation in China was assessed primarily based on six different health system components. Results: 26 policies, regulations, and national strategic plans related to TCI rehabilitation were issued by relevant government departments since 2002; notably, 14 policies related to TCI rehabilitation development were intensively introduced from 2016 to 2021. These policies cover the three main areas of financing, infrastructure development, and service delivery. The National Administration of Traditional Chinese Medicine's investment in TCM clinical capacity infrastructure and scientific research in 2019–2021 increased by 66% compared to 2010–2012, and the average number of TCM hospitals with rehabilitation departments in 2020 increased by 6.5% compared to 2018. The proportion of community health service centers providing TCM services in primary medical and health institutions has increased by 30.8% over the past 10 years. Conclusion: Long-term continuous policies, substantial financial investment, and expansion of the scope of TCI rehabilitation services in primary care institutions have effectively contributed to the rapid development of TCI rehabilitation. However, human resources and financing mechanisms for TCI rehabilitation need further improvement.

CacheSCDefender: VMM-based Comprehensive Framework against Cache-based Side-channel Attacks

( Chao Yang ),( Yunfei Guo ),( Hongchao Hu ),( Wenyan Liu ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.12

Cache-based side-channel attacks have achieved more attention along with the development of cloud computing technologies. However, current host-based mitigation methods either provide bad compatibility with current cloud infrastructure, or turn out too application-specific. Besides, they are defending blindly without any knowledge of on-going attacks. In this work, we present CacheSCDefender, a framework that provides a (Virtual Machine Monitor) VMM-based comprehensive defense framework against all levels of cache attacks. In designing CacheSCDefender, we make three key contributions: (1) an attack-aware framework combining our novel dynamic remapping and traditional cache cleansing, which provides a comprehensive defense against all three cases of cache attacks that we identify in this paper; (2) a new defense method called dynamic remapping which is a developed version of random permutation and is able to deal with two cases of cache attacks; (3) formalization and quantification of security improvement and performance overhead of our defense, which can be applicable to other defense methods. We show that CacheSCDefender is practical for deployment in normal virtualized environment, while providing favorable security guarantee for virtual machines.