Analysis of contact characteristics of ball screws under the combined loads considering non-uniform load distribution

YongJiang Chen,Jianghai Zhao,Chuangfan Yuan,Jingkai Sun 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.4

An analysis model of the contact characteristics of the double-nut preloaded ball screw which can consider the combined action of the axial load and the overturning moment is established, the model can consider non-uniform load distribution, and the validity of the model is verified by experiments. Based on this model, the influence of the combined action of axial load and overturning moment on the average value and distribution fluctuation value of the contact angle of the ball screw, the number of unloaded balls, the distribution fluctuation value of the contact load, and the static contact stiffness and other contact parameters are systematically analyzed, and get the following conclusions: The contact parameters of the ball screw are mainly affected by the axial load and the contact state between the ball and the raceway. The gradually increasing axial load basically reduces the influence of the overturning moment on the contact parameters of the ball screw. There is a critical value of the load in the axial direction within the range of the action value of the preload load. Only when the critical value is above the critical value, the contact parameters will change regularly with the changes in the axial stiffness and overturning moment. However, different critical values for the regular variation of contact parameters with axial load and overturning moment vary.

Novel Adaptive Blanking Regulation Scheme for Constant Current and Constant Voltage Primary-side Controlled Flyback Converter

Yongjiang Bai,Wenjie Chen,Xiaoyu Yang,Xu Yang 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

Primary-side regulation (PSR) scheme is widely applied in low power applications, such as cell phone chargers, network adapters, and LED drivers. However, the efficiency and standby power requirements have been improved to a high standard due to the new trends of DOE (Department Of Energy) Level VI and COC (Code Of Conduct specifications) V5. The major drawbacks of PSR include poor regulation due to inaccurate feedback and difficulty in acquiring acceptable regulation. A novel adaptive blanking strategy for constant current and constant voltage regulation is proposed in this paper. An accurate model for the sample blanking time related to transformer leakage inductance and the metal-oxide-semiconductor field-effect transistor (MOSFET) parasitic capacitance is established. The proposed strategy can achieve accurate detection for ultra-low standby power. In addition, numerous control factors are analyzed in detail to eliminate the influence of leakage inductance on the loop stability. A dedicated controller integrated circuit (IC) with a power MOSFET is fabricated to verify the effectiveness of the proposed control strategy. Experimental results demonstrated that the prototype based on the proposed IC has excellent performance.

Analysis of longissimus muscle quality characteristics and associations with DNA methylation status in cattle

Zhi Chen,Shuangfeng Chu,Xin Xu,Jingyi Jiang,Wenqiang Wang,Hongliang Shen,Mingxun Li,Huimin Zhang,Yongjiang Mao,Zhangping Yang 한국유전학회 2019 Genes & Genomics Vol.41 No.10

Background As cattle represent one of the most important livestock species for meat production, control of muscle development in regards to quality is an important research focus. Objectives In this study, the phenotypic quality traits and its associations with DNA methylation levels of the longissimus muscle in two cattle breeds were studied. Methods The pH value, water loss rate, fat and protein and fatty acid content were measured in three beef cattle breeds of longissimus mucle; The longissimus mucle was analyzed by MethylRAD-seq and RNA-seq. The differentially methylated and differentially expressed related genes were subjected to BSP. Results Methylation status of longissimus mucle was analyzed by MethylRAD-seq. Compared with Simmental, there were 39 differentially methylated and expressed genes in muscle of Yunling cattle, and 123 differentially methylated and expressed genes in Wenshan muscle. A combined analysis of MethylRAD-seq and RNA-seq results revealed differential methylation and expression level of 18 genes between Simmental and Wenshan cattle, and 14 genes between Simmental and Yunling cattle. In addition, 28 genes were differentially methylated between Wenshan and Yunling cattle. Results of promoter methylation analysis of ACAD11, FADS6 and FASN showed that the overall degree of DNA methylation of FADS6 and FASN was negatively correlated with their expression levels. Methylation level of FASN in Simmental was greater than Yunling and Wenshan. The degree of methylation at the FADS6 CpG4 site was significantly higher in Simmental than that in Yunling. The levels of methylation at the CpG7 locus of the Simmental and Yunling breeds were greater than Wenshan cattle. A negative correlation was detected between the methylation levels and the expression of FASN CpG1, CpG2, CpG3, CpG5, CpG7, and CpG10. Conclusion The functional and molecular regulatory mechanism of the genes related to meat quality can be revealed systematically from aspects of the genetic and epigenetic regulation. These studies will help to further explore the molecular mechanisms and phenotypic differences that regulate growth and quality of different breeds of cattle.

Novel Adaptive Blanking Regulation Scheme for Constant Current and Constant Voltage Primary-side Controlled Flyback Converter

Bai, Yongjiang,Chen, Wenjie,Yang, Xiaoyu,Yang, Xu The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

Primary-side regulation (PSR) scheme is widely applied in low power applications, such as cell phone chargers, network adapters, and LED drivers. However, the efficiency and standby power requirements have been improved to a high standard due to the new trends of DOE (Department Of Energy) Level VI and COC (Code Of Conduct specifications) V5. The major drawbacks of PSR include poor regulation due to inaccurate feedback and difficulty in acquiring acceptable regulation. A novel adaptive blanking strategy for constant current and constant voltage regulation is proposed in this paper. An accurate model for the sample blanking time related to transformer leakage inductance and the metal-oxide-semiconductor field-effect transistor (MOSFET) parasitic capacitance is established. The proposed strategy can achieve accurate detection for ultra-low standby power. In addition, numerous control factors are analyzed in detail to eliminate the influence of leakage inductance on the loop stability. A dedicated controller integrated circuit (IC) with a power MOSFET is fabricated to verify the effectiveness of the proposed control strategy. Experimental results demonstrated that the prototype based on the proposed IC has excellent performance.

Transitional Zone Index and Intravesical Prostatic Protrusion in Benign Prostatic Hyperplasia Patients: Correlations according to Treatment Received and Other Clinical Data

Tao Huang,Jun Qi,YongJiang Yu,Ding Xu,Yang Jiao,Jian Kang,YunKai Zhu,YaQing Chen 대한비뇨의학회 2012 Investigative and Clinical Urology Vol.53 No.4

Purpose: The aim of this research was to assess the value of the transitional zone index (TZI) and intravesical prostatic protrusion (IPP) from transrectal ultrasonography in evaluating the severity and progression of disease by analyzing the relationship between the 2 parameters and symptoms, clinical history, and urodynamics in benign prostatic hyperplasia (BPH) patients undergoing different treatment. Materials and Methods: A total of 203 patients receiving medication and 162 patients who underwent transurethral resection of the prostate because of BPH were enrolled in this retrospective analysis. The clinical history and subjective and objective examination results of all patients were recorded and compared after being classified by TZI and IPP level. Linear regression was used to find correlations between IPP, TZI, and urodynamics. Results: The 2 parameters were found to differ significantly between patients receiving medication and patients undergoing surgical therapy (p<0.05). PSA, maximum flow rate (Qmax), detrusor pressure at Qmax (PdetQmax), and the bladder outlet obstruction index (BOOI) differed according to various TZI levels (p<0.05). In addition, the voiding symptom score, Qmax, and BOOI of subgroups with various IPP levels were also significantly different (p<0.05). Both TZI and IPP had significant effects on Qmax, BOOI, and PdetQmax (p<0.05) and the incidence of acute urinary retention (p=0.000). Conclusions: The results demonstrated that both TZI and IPP had favorable value for assessing severity and progression in patients with BPH. Further studies are needed to confirm whether the two parameters have predictive value in the efficacy of BPH treatment and could be considered as factors in the selection of therapy. Purpose: The aim of this research was to assess the value of the transitional zone index (TZI) and intravesical prostatic protrusion (IPP) from transrectal ultrasonography in evaluating the severity and progression of disease by analyzing the relationship between the 2 parameters and symptoms, clinical history, and urodynamics in benign prostatic hyperplasia (BPH) patients undergoing different treatment. Materials and Methods: A total of 203 patients receiving medication and 162 patients who underwent transurethral resection of the prostate because of BPH were enrolled in this retrospective analysis. The clinical history and subjective and objective examination results of all patients were recorded and compared after being classified by TZI and IPP level. Linear regression was used to find correlations between IPP, TZI, and urodynamics. Results: The 2 parameters were found to differ significantly between patients receiving medication and patients undergoing surgical therapy (p<0.05). PSA, maximum flow rate (Qmax), detrusor pressure at Qmax (PdetQmax), and the bladder outlet obstruction index (BOOI) differed according to various TZI levels (p<0.05). In addition, the voiding symptom score, Qmax, and BOOI of subgroups with various IPP levels were also significantly different (p<0.05). Both TZI and IPP had significant effects on Qmax, BOOI, and PdetQmax (p<0.05) and the incidence of acute urinary retention (p=0.000). Conclusions: The results demonstrated that both TZI and IPP had favorable value for assessing severity and progression in patients with BPH. Further studies are needed to confirm whether the two parameters have predictive value in the efficacy of BPH treatment and could be considered as factors in the selection of therapy.

A 1-Dof bidirectional graspable finger mechanism for robotic gripper

Hongliang Hua,Zhenqiang Liao,YongJiang Chen 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.11

The grasping flexibility and control simplicity are essential requirements for robotic gripper. Take above requirements into consideration, we present a 1-Dof four-bar finger mechanism which could produce bidirectional symmetric grasping motion and exhibit a bidirectional grasping ability like soft gripper. The finger mechanism could not only to grasp the object’s outer surface from outside to inside, but also able to extend itself from inside to outside and “grasp” the inner surface of the object. The effects of structural parameters of the finger mechanism on kinematic behavior have been investigated by kinematic modeling and simulations, and some design suggestions are given. A gripper prototype composed of two finger mechanisms is developed, and the effectiveness of the finger mechanism in bidirectional grasping is validated by grasping experiments. Results reveal that due to the symmetrical movement of the two finger mechanisms, they could apply a pair of symmetrical grasping force to the object and keep the stability of the grasping.

A back-drivable linear force actuator for adaptive grasping

Hongliang Hua,Zhenqiang Liao,Xiaofeng Wu,YongJiang Chen,Chun Feng 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8

Robotic gripper is a fundamental component of robot to achieve grasping operations. Grasping force control is an essential requirement for the robotic gripper to achieve adaptive grasping and safety. This paper presents a linear series elastic actuator (LSEA) for robotic grasping applications. The proposed LSEA is characterized as miniature, back-drivable, compact and modular, which could effectively reduce the integrating difficulty of the robotic gripper system. A novel blocking control strategy for actuating force control is proposed to enhance the control stability of the LSEA. Model identification experiments are performed to identify the control models for the actuating force control and self-sensing. Actuating force control experiments are then performed to verify the effectiveness of the established control models. Experimental results reveal that the LSEA could achieve stable actuating force control when interacting with the objects with variable stiffness. An underactuated finger mechanism is utilized to experimentally verify the effectiveness of the proposed LSEA in robotic grasping applications. Results reveal that the grasping adaptability and strength could be controlled by the LSEA in a feedforward approach without the requirement of fingertip force sensor.

Endothelial Aquaporin-1 (AQP1) Expression Is Regulated by Transcription Factor Mef2c

Yong Jiang,He Liu,Wen-jing Liu,Hai-bin Tong,Chang-jun Chen,Fu-gui Lin,Yan-hang Zhuo,Xiao-zhen Qian,Zeng-bin Wang,Yu Wang,Peng Zhang,Hong-liang Jia 한국분자세포생물학회 2016 Molecules and cells Vol.39 No.4

Aquaporin 1 (AQP1) is expressed in most microvascula-ture endothelial cells and forms water channels that play major roles in a variety of physiologic processes. This study aimed to delineate the transcriptional regulation of AQP1 by Mef2c in endothelial cells. Mef2c cooperated with Sp1 to activate human AQP1 transcription by binding to its proximal promoter in human umbilical cord vein endothelial cells (HUVEC). Over-expression of Mef2c, Sp1, or Mef2c/Sp1 increased HUVEC migration and tube-forming ability, which can be abolished AQP1 knockdown. These data indicate that AQP1 is a direct target of Mef2c in regulating angiogenesis and vasculogenesis of endothelial cells.