The working platforms supported with multiple extensible legs must be leveled before they come into operation.Although the supporting stiffness and reliability of the platform are improved with the increasing number o...The working platforms supported with multiple extensible legs must be leveled before they come into operation.Although the supporting stiffness and reliability of the platform are improved with the increasing number of the supporting legs,the increased overdetermination of the multi-leg platform systems leads to leveling coupling problem among legs and virtual leg problem in which some of the supporting legs bear zero or quasi zero loads.These problems make it quite complex and time consuming to level such a multi-leg platform.Based on rigid body kinematics,an approximate equation is formulated to rapidly calculate the leg extension for leveling a rigid platform,then a proportional speed control strategy is proposed to reduce the unexpected platform distortion and leveling coupling between supporting legs.Taking both the load coupling between supporting legs and the elastic flexibility of the working platform into consideration,an optimal balancing legs’ loads(OBLL) model is firstly put forward to deal with the traditional virtual leg problem.By taking advantage of the concept of supporting stiffness matrix,a coupling extension method(CEM) is developed to solve this OBLL problem for multi-leg flexible platform.At the end,with the concept of supporting stiffness matrix and static transmissibility matrix,an optimal load balancing leveling method is proposed to achieve geometric leveling and legs’ loads balancing simultaneously.Three numerical examples are given out to illustrate the performance of proposed methods.This paper proposes a method which can effectively quantify all of the legs’ extension at the same time,achieve geometric leveling and legs’ loads balancing simultaneously.By using the proposed methods,the stability,precision and efficiency of auto-leveling control process can be improved.展开更多
The modular multilevel matrix converter(M3C)is a potential frequency converter for low-frequency AC transmission.However,capacitor voltage control of high-voltage and largecapacity M3C is more difficult,especially for...The modular multilevel matrix converter(M3C)is a potential frequency converter for low-frequency AC transmission.However,capacitor voltage control of high-voltage and largecapacity M3C is more difficult,especially for voltage balancing between branches.To solve this problem,this paper defines sequence circulating components and theoretically analyzes the influence mechanism of different sequence circulating components on branch capacitor voltage.A fully decoupled branch energy balancing control method based on four groups of sequence circulating components is proposed.This method can control capacitor voltages of nine branches in horizontal,vertical and diagonal directions.Considering influences of both circulating current and voltage,a cross decoupled control is designed to improve control precision.Simulation results are taken from a low-frequency transmission system based on PSCAD/EMTDC,and effectiveness and precision of the proposed branch energy balancing control method are verified in the case of nonuniform parameters and an unbalanced power system.展开更多
Estimating the spatial distribution of coseismic slip is an ill-posed inverse problem, and solutions may be extremely oscillatory due to measurement errors without any constraints on the coseismic slip distribution. I...Estimating the spatial distribution of coseismic slip is an ill-posed inverse problem, and solutions may be extremely oscillatory due to measurement errors without any constraints on the coseismic slip distribution. In order to obtain stable solution for coseismic slip inversion, regularization method with smoothness-constrained was imposed. Trade-off parameter in regularized inversion, which balances the minimization of the data misfit and model roughness, should be a critical procedure to achieve both resolution and stability. Then, the active constraint balancing approach is adopted, in which the trade-off parameter is regarded as a spatial variable at each model parameter and automatically determined via the model resolution matrix and the spread function. Numerical experiments for a synthetical model indicate that regularized inversion using active constraint balancing approach can provides stable inversion results and have low sensitivity to the knowledge of the exact character of the Gaussian noise. Regularized inversion combined with active constraint balancing approach is conducted on the 2005 Nias earthquake. The released moment based on the estimated coseismic slip distribution is 9.91×1021 N·m, which is equivalent to a moment magnitude of 8.6 and almost identical to the value determined by USGS. The inversion results for synthetic coseismic uniform-slip model and the 2005 earthquake show that smoothness-constrained regularized inversion method combined with active constraint balancing approach is effective, and can be reasonable to reconstruct coseismic slip distribution on fault.展开更多
In this paper, a formal and systematic method for balancing chemical reaction equations was presented. The results satisfy the law of conservation of matter, and confirm that there is no contradiction to the existing ...In this paper, a formal and systematic method for balancing chemical reaction equations was presented. The results satisfy the law of conservation of matter, and confirm that there is no contradiction to the existing way(s) of balancing chemical equations. A chemical reaction which possesses atoms with fractional oxidation numbers that have unique coefficients was studied. In this paper, the chemical equations were balanced by representing the chemical equation into systems of linear equations. Particularly, the Gauss elimination method was used to solve the mathematical problem with this method, it was possible to handle any chemical reaction with given reactants and products.展开更多
The theory and application of automatic balance technology for the rigid rotor is re- searched. New analysis about the mechanical model of vibratory system is done in view of feature of automatic balance, and the resu...The theory and application of automatic balance technology for the rigid rotor is re- searched. New analysis about the mechanical model of vibratory system is done in view of feature of automatic balance, and the result is that the accurate model of system can be gained by compensa- tion method and the traditional principle error of balance machines both for soft and hard bearing can be overcome. The automatic balance testing theory for sofi and hard bearing machines is pro- posed. The automatic balance system has been developed and the function and technical key is also introduced in detail.展开更多
目的基于金属蛋白酶抑制因子(TIMP)与基质金属蛋白酶(MMP)之间的平衡探讨针刀对兔膝骨关节炎(KOA)模型软骨基质降解的影响。方法采用随机数字表法将24只6月龄,体重(2.0±0.5)kg的健康雄性新西兰兔按照随机数字表法分为空白组、模型...目的基于金属蛋白酶抑制因子(TIMP)与基质金属蛋白酶(MMP)之间的平衡探讨针刀对兔膝骨关节炎(KOA)模型软骨基质降解的影响。方法采用随机数字表法将24只6月龄,体重(2.0±0.5)kg的健康雄性新西兰兔按照随机数字表法分为空白组、模型组和针刀组,各8只。KOA兔模型采用改良Videman法即左后肢伸直位石膏固定6周制备而成。针刀组利用针刀松解筋结病灶点,1次/周,共进行4次治疗;空白组与模型组做相同的抓取,但不采取任何干预。干预结束后1周,采用HE染色形态学、番红固绿染色变化观察各组兔软骨组织病理变化;RT-PCR检测软骨细胞CollagenⅡ、水通道蛋白(AQP)3,TIMP1、MMP13表达水平,Western blot检测CollagenⅡ、AQP3、TIMP、MMP13蛋白表达水平。结果与空白组比较,模型组软骨外观凹凸不平,软骨细胞聚集不规则,部分坏死细胞崩解,潮线紊乱,部分断裂;软骨细胞数量显著下降,软骨基质中番红色显著减少,部分有软骨缺损,潮线模糊且不清晰。与模型组比较,针刀组软骨外观更加平滑,结构层次更加清晰分明,细胞趋于整齐排列,潮线较模型组完整;不仅软骨数量增加,软骨基质中番红着色较正常,而且软骨外表相对光滑平整,潮线也相对完整。与空白组比较,模型组软骨组织CollagenⅡm RNA表达下调,AQP3、TIMP1、MMP13 m RNA表达上调(P<0.05);与模型组比较,针刀组软骨组织CollagenⅡm RNA表达上调,AQP3、TIMP1、MMP13 m RNA表达下调(P<0.05)。与空白组比较,模型组软骨组织CollagenⅡ蛋白表达下调,AQP3、TIMP1、MMP13蛋白表达上调(P<0.05);与模型组比较,针刀组软骨组织CollagenⅡ蛋白表达上调AQP3、MMP13蛋白表达下调(P<0.05);针刀组软骨组织TIMP1蛋白与模型组比较,差异无统计学意义(P>0.05)。与空白组比较,模型组行为学评分升高(P<0.05);与模型组比较,针刀组行为学评分下降(P<0.05)。结论针刀治疗通过调节TIMP/MMP的平衡,达到延缓软骨细胞外基质降解的进程,从而有效降低KOA炎症水平。展开更多
基金supported by Shandong Provincial Natural Science Foundation of China(Grant No.ZR2010EL003)
文摘The working platforms supported with multiple extensible legs must be leveled before they come into operation.Although the supporting stiffness and reliability of the platform are improved with the increasing number of the supporting legs,the increased overdetermination of the multi-leg platform systems leads to leveling coupling problem among legs and virtual leg problem in which some of the supporting legs bear zero or quasi zero loads.These problems make it quite complex and time consuming to level such a multi-leg platform.Based on rigid body kinematics,an approximate equation is formulated to rapidly calculate the leg extension for leveling a rigid platform,then a proportional speed control strategy is proposed to reduce the unexpected platform distortion and leveling coupling between supporting legs.Taking both the load coupling between supporting legs and the elastic flexibility of the working platform into consideration,an optimal balancing legs’ loads(OBLL) model is firstly put forward to deal with the traditional virtual leg problem.By taking advantage of the concept of supporting stiffness matrix,a coupling extension method(CEM) is developed to solve this OBLL problem for multi-leg flexible platform.At the end,with the concept of supporting stiffness matrix and static transmissibility matrix,an optimal load balancing leveling method is proposed to achieve geometric leveling and legs’ loads balancing simultaneously.Three numerical examples are given out to illustrate the performance of proposed methods.This paper proposes a method which can effectively quantify all of the legs’ extension at the same time,achieve geometric leveling and legs’ loads balancing simultaneously.By using the proposed methods,the stability,precision and efficiency of auto-leveling control process can be improved.
基金supported by National Key R&D Program of China(No.2021YFB2401100).
文摘The modular multilevel matrix converter(M3C)is a potential frequency converter for low-frequency AC transmission.However,capacitor voltage control of high-voltage and largecapacity M3C is more difficult,especially for voltage balancing between branches.To solve this problem,this paper defines sequence circulating components and theoretically analyzes the influence mechanism of different sequence circulating components on branch capacitor voltage.A fully decoupled branch energy balancing control method based on four groups of sequence circulating components is proposed.This method can control capacitor voltages of nine branches in horizontal,vertical and diagonal directions.Considering influences of both circulating current and voltage,a cross decoupled control is designed to improve control precision.Simulation results are taken from a low-frequency transmission system based on PSCAD/EMTDC,and effectiveness and precision of the proposed branch energy balancing control method are verified in the case of nonuniform parameters and an unbalanced power system.
基金Projects(41604111,41541036) supported by the National Natural Science Foundation of China
文摘Estimating the spatial distribution of coseismic slip is an ill-posed inverse problem, and solutions may be extremely oscillatory due to measurement errors without any constraints on the coseismic slip distribution. In order to obtain stable solution for coseismic slip inversion, regularization method with smoothness-constrained was imposed. Trade-off parameter in regularized inversion, which balances the minimization of the data misfit and model roughness, should be a critical procedure to achieve both resolution and stability. Then, the active constraint balancing approach is adopted, in which the trade-off parameter is regarded as a spatial variable at each model parameter and automatically determined via the model resolution matrix and the spread function. Numerical experiments for a synthetical model indicate that regularized inversion using active constraint balancing approach can provides stable inversion results and have low sensitivity to the knowledge of the exact character of the Gaussian noise. Regularized inversion combined with active constraint balancing approach is conducted on the 2005 Nias earthquake. The released moment based on the estimated coseismic slip distribution is 9.91×1021 N·m, which is equivalent to a moment magnitude of 8.6 and almost identical to the value determined by USGS. The inversion results for synthetic coseismic uniform-slip model and the 2005 earthquake show that smoothness-constrained regularized inversion method combined with active constraint balancing approach is effective, and can be reasonable to reconstruct coseismic slip distribution on fault.
文摘In this paper, a formal and systematic method for balancing chemical reaction equations was presented. The results satisfy the law of conservation of matter, and confirm that there is no contradiction to the existing way(s) of balancing chemical equations. A chemical reaction which possesses atoms with fractional oxidation numbers that have unique coefficients was studied. In this paper, the chemical equations were balanced by representing the chemical equation into systems of linear equations. Particularly, the Gauss elimination method was used to solve the mathematical problem with this method, it was possible to handle any chemical reaction with given reactants and products.
文摘The theory and application of automatic balance technology for the rigid rotor is re- searched. New analysis about the mechanical model of vibratory system is done in view of feature of automatic balance, and the result is that the accurate model of system can be gained by compensa- tion method and the traditional principle error of balance machines both for soft and hard bearing can be overcome. The automatic balance testing theory for sofi and hard bearing machines is pro- posed. The automatic balance system has been developed and the function and technical key is also introduced in detail.
文摘目的基于金属蛋白酶抑制因子(TIMP)与基质金属蛋白酶(MMP)之间的平衡探讨针刀对兔膝骨关节炎(KOA)模型软骨基质降解的影响。方法采用随机数字表法将24只6月龄,体重(2.0±0.5)kg的健康雄性新西兰兔按照随机数字表法分为空白组、模型组和针刀组,各8只。KOA兔模型采用改良Videman法即左后肢伸直位石膏固定6周制备而成。针刀组利用针刀松解筋结病灶点,1次/周,共进行4次治疗;空白组与模型组做相同的抓取,但不采取任何干预。干预结束后1周,采用HE染色形态学、番红固绿染色变化观察各组兔软骨组织病理变化;RT-PCR检测软骨细胞CollagenⅡ、水通道蛋白(AQP)3,TIMP1、MMP13表达水平,Western blot检测CollagenⅡ、AQP3、TIMP、MMP13蛋白表达水平。结果与空白组比较,模型组软骨外观凹凸不平,软骨细胞聚集不规则,部分坏死细胞崩解,潮线紊乱,部分断裂;软骨细胞数量显著下降,软骨基质中番红色显著减少,部分有软骨缺损,潮线模糊且不清晰。与模型组比较,针刀组软骨外观更加平滑,结构层次更加清晰分明,细胞趋于整齐排列,潮线较模型组完整;不仅软骨数量增加,软骨基质中番红着色较正常,而且软骨外表相对光滑平整,潮线也相对完整。与空白组比较,模型组软骨组织CollagenⅡm RNA表达下调,AQP3、TIMP1、MMP13 m RNA表达上调(P<0.05);与模型组比较,针刀组软骨组织CollagenⅡm RNA表达上调,AQP3、TIMP1、MMP13 m RNA表达下调(P<0.05)。与空白组比较,模型组软骨组织CollagenⅡ蛋白表达下调,AQP3、TIMP1、MMP13蛋白表达上调(P<0.05);与模型组比较,针刀组软骨组织CollagenⅡ蛋白表达上调AQP3、MMP13蛋白表达下调(P<0.05);针刀组软骨组织TIMP1蛋白与模型组比较,差异无统计学意义(P>0.05)。与空白组比较,模型组行为学评分升高(P<0.05);与模型组比较,针刀组行为学评分下降(P<0.05)。结论针刀治疗通过调节TIMP/MMP的平衡,达到延缓软骨细胞外基质降解的进程,从而有效降低KOA炎症水平。
