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| 1 | Effect of age on the pharmacokinetics of polymorphic nimodipine in rats after oral administration显示文摘The previous investigation has proved that their existed pharmacokinetic difference between the different crystal forms of the polymorphic drugs after oral administration.However,no systemic investigations have been made on the change of this pharmacokinetic difference,resulted either from the physiological or from the pathological factors.In this paper,we used polymorphic nimodipine(Nim) as a model drug and investigated the effect of age difference(2- and 9-month old) on the pharmacokinetics after oral delivery in rats.As the results shown,for L-form of Nim(L-Nim),the AUC0–24 hin 2-month-old rats was 343.68747.15 ng h/m L,which is 23.36% higher than that in 9-month-old rats.For H-form of Nim(H-Nim),the AUC0–24 hin 2-monthold rats was 140.91719.47 ng h/m L,which is 54.64% higher than that in 9-month-old rats.The AUC0–24 h ratio between H-Nim and L-Nim was 2.44 in 2-month-old rats and 3.06 in 9-month-old rats.Since age difference could result in unparallelled change of the absorption and bioavailability of the polymorphic drugs,the results in this experiment are of value for further investigation of crystal form selection in clinical trials and rational clinical application of the polymorphic drugs. | Wenli Liu Xiaona Wang Ruilian Chen Kaixuan Zhang Yao Li Yi Li Duanyun Si Junbo Gong Dianshu Yin Yongli Wang Zhenping Wei Mingshi Yang | 2016 | Acta Pharmaceutica Sinica B2016，6，5： | 3 |
| 2 | Sensitivity Analysis,Determination and Optimization of Granite RHT Parameters显示文摘The RHT model has 34 parameters,among which 19 parameters can be obtained by experiments or theoretical calculations and the remaining 15 parameters are difficult to acquire.In this study,firstly,10 Hopkinson impact tests were conducted to acquire the typical stress-strain curves of granite under dynamic loads.Through the sensitivity analysis,it is found that 13 of the 15 difficult-acquired parameters are effective to affect the shape of the stress-strain curve,and the other two parameters have no effect.Following the initial determination of model parameters with reference to the concrete RHT model,a new approach is proposed to optimize the 13 influential parameters through the LS-DYNA numerical simulation and orthogonal experiments.Finally,the determined granite RHT model parameters are verified by the results of Hopkinson impact tests conducted in this study and the bullet penetration test by Wang et al.Both results of the numerical simulations are in a good agreement with the tested results,which validates the suitability of the proposed method to acquire RHT model parameters for granite and the other rocks. | Hongchao Li Yong Chen Dianshu Liu Lei Zhao Greg You | 2019 | Journal of Beijing Institute of Technology2019，28，1： | 2 |
| 3 | Parameters Sensitivity Analysis and Correction for Concrete Damage Plastic Model显示文摘In order to understand the effect of hardening ductility parameters and softening ductility parameters of the concrete damage plastic model in LS-DYNA,a sensitivity and reliability analysis of these parameters through a convenient cube unit test was conducted. The results showed that the peak strength strain was independent of the hardening ductility parameter DH,but affected by AH,BH,and CH. The softening ductility was mainly related to the softening ductility parameter AS,but not affected by the damage ductility exponent BS. In case that the model with default parameters failed to match the AS-controlled damage softening phase,an optimized model with an AS correction was developed. The corrected model with the AS value of 2 matched well with the code model,and exhibited good feasibility in predicting the stress-strain curve of different grades of concrete. Moreover,the practicability of the corrected model was further validated by the conventional triaxial test. The simulated curve exhibited favorable consistence with the trial curve. Therefore,the model with parameter correction could provide a prospective reference for predicting the mechanical properties of concrete. | Yaqin Jiang Pengfei Xu Chengzhi Wang Dianshu Liu | 2018 | Journal of Beijing Institute of Technology2018，27，1： | 1 |
| 4 | Attenuation Parameters of Blasting Vibration by Fuzzy Nonlinear Regression Analysis显示文摘In order to reduce the influence of outliers on the parameter estimate of the attenuation formula for the blasting vibration velocity,a fuzzy nonlinear regression method of Sadov’s vibration formula was proposed on the basis of the fuzziness of blasting engineering,and the algorithm was described in details as well.In accordance with an engineering case,the vibration attenuation formula was regressed by the fuzzy nonlinear regression method and the nonlinear least square method,respectively.The calculation results showed that the fuzzy nonlinear regression method is more suitable to the field test data.It differs from the nonlinear least square method because the weight of residual square in the objective function can be adjusted according to the membership of each data.And the deviation calculation of least square estimate of parameters in the nonlinear regression model verified the rationality of using the membership to assign the weight of residual square.The fuzzy nonlinear regression method provides a calculation basis for estimating Sadov’s vibration formula’s parameters more accurately. | Chen Li Shufeng Liang Yongchao Wang Long Li Dianshu Liu | 2020 | Journal of Beijing Institute of Technology2020，29，4： | 0 |
| 5 | Dynamic Mechanical Characteristics and Damage Evolution Model of Granite显示文摘By using the technique of the split Hopkinson pressure bar( SHPB),impact tests at different stress wavelengths( 0. 8-2. 0 m) and strain rates( 20-120 s^(-1)) were conducted to study the dynamic mechanical properties and damage accumulation evolution lawof granite. Test results showthat the dynamic compressive strength and strain rate of granite have a significantly exponential correlation;the relationship between peak strain and strain rate is approximately linear,and the increase of wavelengths generally makes the level of peak strain uplift. The multiple-impacts test at a lowstrain rate indicates that at the same wavelength,the cumulative damage of granite shows an exponential increasing form with the increase of strain rate; when keeping the increase of strain rate constant and increasing the stress wavelength,the damage accumulation effect of granite is intensified and still shows an exponential increasing form; under the effect of multiple impacts,the damage development trend of granite is similar overall,but the increase rate is accelerating. Therefore the damage evolution model was established on the basis of the exponential function while the physical meaning of parameters in the model was determined. The model can reflect the effect of the wave parameters and multiple impacts. The validity of the model and the physical meaning of the parameters were verified by the test,which further offer a reference for correlational research and engineering application for the granite. | Shuaifeng Wu Yingqi Wei Hong Cai Bei Jia Dianshu Liu | 2018 | Journal of Beijing Institute of Technology2018，27，2： | 0 |
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