Theoretical Analysis and Experimental Study on the Influence of Magnet Structure on Sealing Capacity of Magnetic Fluid Seal

Yanhong Cheng,Zhongzhong Wang,Decai Li 한국자기학회 2019 Journal of Magnetics Vol.24 No.3

The Magnetic fluid is a new type of magnetic material. It is a colloidal liquid made of nanoscale ferromagnetic particles suspended in a carrier fluid. Magnetic fluid sealing is one of the most successful applications of the magnetic fluid. As a new type of seal with the advantages of no leakage, long life and high reliability, magnetic fluid seal has been widely used under vacuum and low pressure differential condition. Two types of permanent magnets, the annular permanent magnets and the cylindrical magnets, are usually used in magnetic fluid seals in engineering. However, the influence of permanent magnet structure on sealing capacity was not clear, hence a new experimental setup was designed in order to study the influence of permanent magnet structure on sealing capacity. The annular permanent magnets and the cylindrical magnets were used as the magnetic source of the experimental setup in a series of tests respectively. The relationship between the sealing capacity of magnetic fluid seal and the end-face area, axial length of the magnet was analyzed by the electromagnetism theories and theoretical derivation. The result of the experiments shows that the sealing capability grows with the end-face area of the magnet, and the growth rate becomes much slower when magnet end-face area attains a certain value; the reluctance of pole pieces and shaft can’t be ignored when magnetic field attains a certain value; the modified theoretical formula had a good match to the measured values when the end-face area of the magnet is small enough to ignore the reluctance of pole pieces and shaft.

Variation of sexual dimorphism and asymmetry in disease expression of inflammatory arthritis among laboratory mouse models with different genomic backgrounds

Wei Dong,Cheng Tian,Z. Galvin Li,David Brand,Yanhong Cao,Xiaoyun Liu,Jiamin Ma,Andy Chai,LindaK.myers,Jian Yan,Karen Hasty,John Stuart,Yan Jiao,Weikuan Gu,Xiaojun Cai 한국실험동물학회 2023 Laboratory Animal Research Vol.39 No.4

Sex difference has shown in the arthritis diseases in human population and animal models. We investigate how the sex and symmetry vary among mouse models with different genomic backgrounds. Disease data of sex and limbs accumulated in the past more than two decades from four unique populations of murine arthritis models were analyzed. They are (1) interleukin-1 receptor antagonist (IL-1ra) deficient mice under Balb/c background (Balb/c KO); (2) Mice with collagen II induced arthritis under DBA/1 background; (3) Mice with collagen II induced arthritis under C57BL/6 (B6) background and (4) A F2 generation population created by Balb/c KO X DBA/1 KO. Our data shows that there is a great variation in sexual dimorphism for arthritis incidence and severity of arthritis in mice harboring specific genetic modifications. For a F2 population, the incidence of arthritis was 57.1% in female mice and 75.6% in male mice. There was a difference in severity related to sex in two populations: B6.DR1/ B6.DR4 (P < 0.001) and F2 (P = 0.023) There was no difference Balb/c parental strain or in collagen-induced arthritis (CIA) in DBA/1 mice. Among these populations, the right hindlimbs are significantly higher than the scores for the left hindlimbs in males (P < 0.05). However, when examining disease expression using the collagen induced arthritis model with DBA/1 mice, sex-dimorphism did not reach statistical significance, while left hindlimbs showed a tendency toward greater disease expression over the right. Sexual dimorphism in disease expression in mouse models is strain and genomic background dependent. It sets an alarm that potential variation in sexual dimorphism among different racial and ethnic groups in human populations may exist. It is important to not only include both sexes and but also pay attention to possible variations caused by disease expression and response to treatment in all the studies of arthritis in animal models and human populations.

Analysis and Optimization of an Internal Feedback Hydrostatic Turntable Oil Pad Power Consumption Based on Finite Difference Method

Congbin Yang,Shuaihua Shao,Yanhong Cheng,Zhifeng Liu,Yongsheng Zhao 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.12

The hydrostatic turntable is a critical component of numerous CNC machine tools, as it performs a supporting function and enables precise rotary motion. To ensure that high-precision CNC machines can operate under heavy loads, it is imperative to minimize power consumption. The power consumption of a hydrostatic turntable is affected by various factors, such as oil viscosity, initial oil film thickness, and oil pad structure. This study focuses on investigating a hydrostatic turntable with internal feedback. The Reynolds equation of the sector oil pad is solved using the finite difference method to establish the pressure distribution model. Subsequently, the study examines the power consumed by the axial oil pad at different initial oil film thickness, lubricating oil viscosity, and sealing edge width. To minimize power consumption caused by the axial oil pad, this paper employs the genetic algorithm to identify optimal design parameters within specified constraints. Additionally, the load-bearing performance of the optimized axial oil pad is checked to ensure that the load-bearing capacity and stiffness meet the requirements. Finally, the use of simulation software for oil pads in finite element simulation can preliminarily demonstrate the reliability of the proposed method.

Association between Magnetic Resonance Imaging Findings of the Pelvic Floor and de novo Stress Urinary Incontinence after Vaginal Delivery

Na Li,Can Cui,Yue Cheng,Yanhong Wu,Jianzhong Yin,Wen Shen 대한영상의학회 2018 Korean Journal of Radiology Vol.19 No.4

Objective: The study aimed to evaluate the contributions of levator ani muscle (LAM) injury, vesical neck movement, urethral length and mobility, and urethral sphincter dysfunction observed on magnetic resonance imaging (MRI) towards stress urinary incontinence (SUI) after vaginal delivery. Materials and Methods: Fifty primiparous women after 6 months of delivery (15 with SUI and 35 without) and 35 nulliparous as continent controls underwent MRI at rest and Valsalva maneuver. A published levator ani scoring system was used to characterize morphological changes of LAM. The severity of the injury was divided into three categories as none, minor, and major. A series of common parameters including levator plate angle, iliococcygeal angle, and levator hiatus were used to describe the functional conditions of LAM. Urethral mobility was defined based on the rotation of the urethra between Valsalva and rest status. Vesical neck movement was evaluated by its distance to the pubococcygeal line. Urethral sphincter dysfunction was defined as the widening of the proximal urethra and/or funneling at the urethrovesical junction during Valsalva. Results: Primiparous incontinent (PI) women had additional major levator ani defects (33.3% vs. 17.1%) while less minor defects (0.7% vs. 31.4%) than primiparous continent (PC) women. Vesical neck downward movement in PI women was more obvious than PC women (28.5 mm vs. 24.2 mm, p = 0.006). Urethral mobility was more active in primiparous women than in nulliparous continent controls (57.4 vs. 52.4), whereas no difference was observed on urethral mobility in the primiparous group (p = 0.25). Urethral sphincter dysfunction and funneling were present in 80% of PI women versus 22.9% in PC women (p < 0.001). Conclusion: The MRI findings revealed that de novo SUI was associated with major LAM injury, vesical neck downward movement as well as urethral sphincter dysfunction. Vesical neck funneling on sagittal images can be treated as a valuable predictor for SUI. The intervention for the PI should focus on the elevation of vesical neck, rehabilitation of LAM as well as recovery of the urethral sphincter muscle.