Performance characteristics around the TDC of linear compressor based on whole-process simulation

Huiming Zou,Mingsheng Tang,HONGBO XU,SHUANGQUAN SHAO,Changqing Tian 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.10

A whole-process simulation platform is established for linear compressor to analyze the performance characteristics on different pistondisplacement conditions from small oscillation without pumping till to rushing out of the top dead center (TDC). The measuring methodsof the related parameters in the model are presented and the values of these parameters are obtained from an actual test. The simulatedresults agreed well with the experimental results under the same working conditions. The errors of the effective voltage, the effectivecurrent, the compression efficiency and the phase angle between the current and the displacement were within ±6.9%,±8.5%,±6.2%and±13.4%, respectively. Based on this simulation platform, the performance characteristic around the TDC of the linear compressor ondifferent working conditions is analyzed. The performance comparison on 60 Hz shows that the compression efficiency near to the TDCon 0.7 MPa is higher than that on 0.5 MPa because the phase angle α under that condition is around 90°, but the operation reliability on0.7 MPa is worse than that on 0.5 MPa because the jump phenomenon happens when the piston displacement goes near to the TDC. Thejump phenomenon results in unstable operation as the piston displacement jumps from the position before the TDC to the position afterthe TDC. According to the simulation on different power frequency, two important performance characteristics are inferred. One is thatthere is an inflection point in the curve of the phase angle α versus the displacement at the TDC. This characteristic is a good choice forthe TDC detection. The other is that the jump phenomenon is prone to happening when there exist different displacement responses onthe same voltage value, becoming inconspicuous when the power frequency is decreased and disappearing when the power frequency isincreased. Based on this characteristic, the jump phenomenon can be avoided through suitable system configuration and frequency adjustment.

On the Disturbance Rejection Control of Flexible-joint Robot: A GPIO-based Approach

Huiming Wang,Yang Zhang,Xiaolei Chen,Xianlun Tang,I-Ming Chen 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.8

A robust disturbance rejection control scheme is addressed for the trajectory tracking problem of a flexible-joint robot (FJR). The system is always severely affected by various types of unknown disturbances including model errors, couplings, changing working environments as well as unmodeled dynamics. These disturbances on the link and actuator side will deteriorate the control performance of FJR. By considering all the disturbances as an unknown lumped time-varying disturbance, a flatness description of FJR is developed. Then, a new output feedback controller is constructed through the estimates of unmeasurable states and unknown lumped disturbance provided by a generalized proportional integral observer (GPIO). The stability of the closed-loop system with the driven of the proposed control scheme is guaranteed under some mild assumptions. Compared with the conventional linear active disturbance rejection control (LADRC) scheme, test results are presented to demonstrate the feasibility and efficacy of the proposed control approach.

Numerical Modelling Study of the Load Sharing Law of Anti-sliding Piles based on the Soil Arching Effect for Erliban Landslide, China

Changdong Li,Huiming Tang,Xinli Hu,Liangqing Wang 대한토목학회 2013 KSCE JOURNAL OF CIVIL ENGINEERING Vol.17 No.6

This paper presents a new model of the load sharing law with a three-stage load sharing pattern via a representative case study in the Three Gorges reservoir region, China. A definitive new three-stage load transfer pattern is presented, including end-bearing soil arching, friction soil arching and the sliding mass in front of the pile. By means of the soil arching effect between the anti-sliding pile and landslide mass, the law of the load sharing ratio under different cases, including different intervals, section dimensions, driving forces, and shearing parameters of the sliding mass and the pile-soil interface, is presented by using the explicit finite-difference numerical modelling method. The results show that (a) the effect scale of the soil arching effect is within the scale of four times of the width of the pile; (b) the soil arching only exits within a certain pile interval, and it will become inefficiency beyond the maximum pile interval; (c) there is a threshold value for the cohesion strength parameters of the sliding mass, beyond which the load sharing ratios of soil arching keep in a steady level.

Deep Displacement of Huangtupo Landslide in Three Gorges Reservoir Area, China

( Sha Lu ),( Huiming Tang ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Huangtupo landslide, one of the biggest and most complicated landslides in the Three Gorges Reservoir area, is located in the old site of Badong county. The deformation and stability condition are closely related to human lives and properties. Field investigation and monitoring methods are adopted in revealing the spatial distribution and deformation conditions of slip zone. The results show that there are two slip zones in the upper and lower part of Sub-landsldie#1. The major lower slip zone is located at the eastern part of Sub-landsldie#1. The cumulative displacement at the front of No.1 Sub-landslide is between 157.23mm and 199.09mm. The value in the middle part of No.1 Sub-landslide is 256.78mm and 184.7mm from two monitoring site. At the edge of No.1 Sub-landslide, the cumulative displacement is 72.51mm. Multi-fractal dimension was adopted to reveal the shallow deformation evolution characteristics of No.1 Sub-landslide. The multi-fractal dimension values are relatively big and the affects a lot by rainfall and water level but the landslide is in a relatively stable condition. In the study of deep formation of Huangtupo landslide, in No.1 Sub-landslide, the cumulative displacement at the slip zone increase steadily from 0mm to 54.32mm. The maximum value of monthly deformation rate of the slip zone decrease from the front to the edge of No.1 Sub-landslide. The multi-fractal dimension of the deep displacement shows similar trend with that of shallow part of No.1 Sub-landslide.

Energy analysis of the deformation and failure process of sandstone and damage constitutive model

Tao Wen,Huiming Tang,Junwei Ma,Junwei Ma 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.2

The damage theory was introduced to clarify and simulate the strain softening property of rocks. On the basis of the theory, an energy method was utilized to portray the rock mechanical properties from microscopic perspective. Firstly, from the perspective of rock microstructure, damage variable (expressed as D) was redefined by dividing the rock into three portions: undamaged materials, damaged materials and micro-defects, and an impact factor was introduced as the connection between the damaged material and the micro-defects. Meanwhile, the method for determining the impact factor was presented. Secondly, the damage variable was redefined in light of energy dissipation, then damage evolution analysis was conducted based on triaxial tests. An improved rock damage constitutive model was further obtained in another expression to reflect the energy change law. Subsequently, the relationship between D and the deformation and failure process of rocks was analyzed on account of the damage evolution equation formularized by fitting to a logistic function, which can measure the influence of energy dissipation on the propagation of micro-defects. By comparing between experimental results and theoretical results of illustrative examples, the effectiveness of the improved model was validated, and the its application was also discussed.

Deformation and Failure Mechanism of Brittle Rocks under Loading and Unloading Conditions in High Stress Area

( Tao Wen ),( Huiming Tang ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Excavation of rock mass slope engineering is a complex loading and unloading process. The rock’s strength, deformation and failure are greatly different under loading and unloading conditions. This study presents the research on the deformation and failure mechanism of rock under loading and unloading and its application in high stress area, choosing Dabenliu high slope in the Jinping hydropower station as the typical research object, analyzing the deformation mechanism of the slope based on geotechnical investigation, acquiring the mechanical parameters of rock based on the laboratorical tests, building rock damage constitutive model, determining the mechanical parameters of rock masses based on quality evaluation system of rock mass, finally analyzing the deformation mechanism and the slope stability considering the unloading and damage effects based on numerical simulation. The research output will provide theoretical guarantee to the successful construction and safe operation of similar projects and have important theoretical significance as well as engineering practical value.

Gene expression involved in dark-induced leaf senescence in zoysiagrass (Zoysia japonica)

Xiaoxia Cheng,Xiaomei Dai,Huiming Zeng,Yunxia Li,Wei Tang,Liebao Han 한국식물생명공학회 2009 Plant biotechnology reports Vol.3 No.4

Zoysiagrass (Zoysia japonica) is one of the important turfgrass species. Extending green period of zoysiagrass via delaying leaf senescence will make this species have more potential in the turfgrass industry. In this study, we found that zoysiagrass seedlings treated with GA3 could delay the leaf senescence induced by darkness. To study expression of genes responsive to staying green in zoysiagrass, suppression subtractive hybridization (SSH) was used to identify differentially expressed genes between non-GA3-treated and GA3-treated seedlings subjected to darkness. A total of 307 ESTs were generated, of which 226 ESTs clustered into 54 contigs and 81 were singlets. Differentially expressed genes selected by subtractions were classified into six categories according to their putative functions generated by BLAST analysis. Expression of five selected genes, Met, SAM, V-ATPase, Cry (Cryptochrome gene), and An (diphthine synthase gene) were examined by RT-PCR and Real-time PCR. Both RT-PCR and Real-time PCR results demonstrated that the differential expressions of these genes were attributable to delaying senescence by exogenously applied gibberellic acid. This is the first genome-wide study of senescence in a species of turfgrass. Zoysiagrass (Zoysia japonica) is one of the important turfgrass species. Extending green period of zoysiagrass via delaying leaf senescence will make this species have more potential in the turfgrass industry. In this study, we found that zoysiagrass seedlings treated with GA3 could delay the leaf senescence induced by darkness. To study expression of genes responsive to staying green in zoysiagrass, suppression subtractive hybridization (SSH) was used to identify differentially expressed genes between non-GA3-treated and GA3-treated seedlings subjected to darkness. A total of 307 ESTs were generated, of which 226 ESTs clustered into 54 contigs and 81 were singlets. Differentially expressed genes selected by subtractions were classified into six categories according to their putative functions generated by BLAST analysis. Expression of five selected genes, Met, SAM, V-ATPase, Cry (Cryptochrome gene), and An (diphthine synthase gene) were examined by RT-PCR and Real-time PCR. Both RT-PCR and Real-time PCR results demonstrated that the differential expressions of these genes were attributable to delaying senescence by exogenously applied gibberellic acid. This is the first genome-wide study of senescence in a species of turfgrass.

Heterologous expression of the Arabidopsis DREB1A/CBF3 gene enhances drought and freezing tolerance in transgenic Lolium perenne plants

Li, Xue,Cheng, Xiaoxia,Liu, Jun,Zeng, Huiming,Han, Liebao,Tang, Wei The Korean Society of Plant Biotechnology 2011 Plant biotechnology reports Vol.5 No.1

The dehydration-responsive element binding proteins (DREB1)/C-repeat (CRT) binding factors (CBF) function as transcription factors and play an important role in agricultural biotechnology and molecular biology studies of drought and freezing stress tolerance. We generated transgenic Lolium perenne plants containing the PCR-cloned Arabidopsis DREB1A/CBF3 gene (AtDREB1A/CBF3) to study the function of this gene construct in drought and freezing tolerance in a species of turfgrass. Compared to the control, AtDREB1A/CBF3 transgenic L. perenne plants showed enhanced drought and freezing stress tolerance. The activities of the enzymes superoxide dismutase (SOD) and peroxidase (POD) were higher in transgenic plants than in the non-transgenic plant control. These results demonstrate that the expression of the AtDREB1A/CBF3 gene in transgenic L. perenne plants enhanced drought and freezing tolerance and that the increased stress tolerance was associated with the increased activities of antioxidant enzymes. These results are relevant to stress biology and biotechnology studies of turfgrass.

UAV-Based Remote Sensing and Risk Assessment of Rockfalls in Guangzhou, China

( Wenping Gong ),( Zhan Cheng ),( Bing Li ),( Huiming Tang ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

Unmanned Aerial Vehicle (UAV) technique has been extensively applied in geohazards assessment. In this study, we illustrate the advantages of the UAV technique in the remote sensing and risk assessment of rockfalls, through a case study of the rockfalls located in Guangzhou, China; in which, the UAV images collected are adopted for identifying both potential rockfalls and geohazards bearing bodies. On the basis of a visual inspection of the high-resolution aerial photographs, the potential rockfalls are readily identified. Then, the post-failure runout behavior of the identified rockfalls is analyzed with the numerical software of particle flow code (PFC). Due to the inherent uncertainty in the determination of the micro-parameters in the PFC models, the micro-parameters required in the PFC modelling are calibrated as random variables. With the aid of the Monte Carlo simulation (MCS), the distributions of the runout distance and the velocity of the rockfalls could be obtained. From there, the zones that might be impacted by the rockfalls and the destructive forces on the potential geohazards bearing bodies (i.e., buildings) in these zones can be evaluated. Further, the geohazards bearing bodies in the zones that are impacted by the rockfalls are recognized with an automated image recognition model, which is based upon a deep learning-based image recognition technique of RetinaNet. On the basis of the post-failure runout behavior analysis of the rockfalls and the geohazards bearing bodies recognized, a rapid risk assessment of the rockfalls in the studied region can be conducted.

Selection of high transfer stability and optimal power-efficiency tradeoff with respect to distance region for underground wireless power transfer systems

Xu, Yu,Chen, Qili,Tian, Detian,Zhang, Yongquan,Li, Bo,Tang, Huiming The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.6

Magnetic resonant wireless power transfer (MR-WPT) has become a significant method for powering the measurement units in landslide monitoring boreholes. This paper focuses on the effects of quality factor, coupling distance and load on the power transfer stability, sensitivity and performance of an MR-WPT system. Firstly, through a numerical model of an MR-WPT, the effect of quality factor and coupling distance on the output power, transfer efficiency and frequency splitting phenomenon of MR-WPT systems have been comparatively analyzed. The relationship between the load and the coupling distance region corresponding to optimal transfer performance has been studied. Results show that improving the quality factor of the coils is beneficial for the transfer performance and stability of WPT system. Furthermore, through the selection of the load, a coupling distance region with high transfer stability and an optimal tradeoff between power and efficiency can be obtained. Finally, the above theoretical simulation results have been verified by experimental results.