Abstract: The current method to solve the problem of active suspension control for a vehicle is often dealt with a quarter-car or half-car model. But it is not enough to use this kind of model for practical applicatio...Abstract: The current method to solve the problem of active suspension control for a vehicle is often dealt with a quarter-car or half-car model. But it is not enough to use this kind of model for practical applications. In this paper, based on considering the influence of factors such as, seat and passengers, a MDOF(multi-degree-of-freedom) model describing the vehicle motion is set up. The MODF model, which is 8DOF of four independent suspensions and four wheel tracks, is more applicable by comparison of its analysis result with some conventional vehicle models. Therefore, it is more suitable to use the 8DOF full-car model than a conventional 4DOF half-car model in the active control design for car vibration. Based on the derived 8DOF model, a controller is designed by using LQ (linear quadratic ) control theory, and the appropriate control scheme is selected by testing various performance indexes. Computer simulation is carried out for a passenger car running on a road with step disturbance and random road disturbance expressed by Power Spectral Density (PSD). Vibrations corresponding to ride comfort are derived under the foregoing road disturbances. The response results for uncontrolled and controlled system are compared. The response of vehicle vibration is greatly suppressed and quickly damped, which testifies the effect of the active suspension. The results achieved for various controllers are compared to investigate the influence of different control schemes on the control effect.展开更多
This paper presents a MDOF (multi-degree-of-freedom) model to describe the vehicle motion, considering influences of factors such as, seat and passengers. The model is four-independent-suspension and four-wheel-track ...This paper presents a MDOF (multi-degree-of-freedom) model to describe the vehicle motion, considering influences of factors such as, seat and passengers. The model is four-independent-suspension and four-wheel-track with 8DOF, and has proved more appropriate compared with some conventional vehicle models. Based on the derived 8DOF model, a controller for this model is designed by the use of H∞ control theory, Furthermore the appropriate control scheme is selected by testing various performance indexes. The study shows that satisfying results can be obtained by using an appropriate vehicle model, even if a low order controller and a general control strategy are adopted.展开更多
Background：Information on above-ground biomass（AGB） is important for managing forest resource use at local levels,land management planning at regional levels,and carbon emissions reporting at national and internati...Background：Information on above-ground biomass（AGB） is important for managing forest resource use at local levels,land management planning at regional levels,and carbon emissions reporting at national and international levels.In many tropical developing countries,this information may be unreliable or at a scale too coarse for use at local levels.There is a vital need to provide estimates of AGB with quantifiable uncertainty that can facilitate land use management and policy development improvements.Model-based methods provide an efficient framework to estimate AGB.Methods：Using National Forest Inventory（NFI） data for a^1,000,000 ha study area in the miombo ecoregion,Zambia,we estimated AGB using predicted canopy cover,environmental data,disturbance data,and Landsat 8 OLI satellite imagery.We assessed different combinations of these datasets using three models,a semiparametric generalized additive model（GAM） and two nonlinear models（sigmoidal and exponential）,employing a genetic algorithm for variable selection that minimized root mean square prediction error（RMSPE）,calculated through cross-validation.We compared model fit statistics to a null model as a baseline estimation method.Using bootstrap resampling methods,we calculated 95% confidence intervals for each model and compared results to a simple estimate of mean AGB from the NFI ground plot data.Results：Canopy cover,soil moisture,and vegetation indices were consistently selected as predictor variables.The sigmoidal model and the GAM performed similarly;for both models the RMSPE was -36.8 tonnes per hectare（i.e.,57% of the mean）.However,the sigmoidal model was approximately 30% more efficient than the GAM,assessed using bootstrapped variance estimates relative to a null model.After selecting the sigmoidal model,we estimated total AGB for the study area at 64,526,209 tonnes（＋/- 477,730）,with a confidence interval 20 times more precise than a simple designbased estimate.Conclusions：Our findings demonstrate that NFI data may be combined with freely available satellite imagery and soils data to estimate total AGB with quantifiable uncertainty,while also providing spatially explicit AGB maps useful for management,planning,and reporting purposes.展开更多
Zeolitic imidazolate framework-8(ZIF-8) was prepared through a solve-thermal reaction method and then shaped using different additives. The in fluence of the shaping conditions on the microstructure of the shaped samp...Zeolitic imidazolate framework-8(ZIF-8) was prepared through a solve-thermal reaction method and then shaped using different additives. The in fluence of the shaping conditions on the microstructure of the shaped samples was characterized by the XRD, BET, and SEM techniques. The results demonstrate that the compressive strength of the various shaped tablets is greatly increased and capable of meeting the industrial requirements compared to the unshaped ZIF-8 and that the loss rate of speci fic surface areas was maintained at 10% after the addition of 10%(by mass) binder and 10%(by mass) solvent. The adsorption isotherms of CO2, CH4, C3H8, and C3H6 on powdery ZIF-8and the shaped tablets(T-shaped ZIF-8, C-shaped ZIF-8, and N-shaped ZIF-8) were determined through volumetric measurements under different pressures and temperatures(298.2, 323.2, and 348.2 K). The adsorption capacities of the gases on both the ZIF-8 powder and the shaped tablets follow the order C3H6 N C3H8N CO2 N CH4. Furthermore,the results show that the adsorption capacities of the gases on the shaped tablets are lower by approximately 10%–20% than those on the powdery ZIF-8. In fact, the adsorption equilibrium isotherms for CO2, CH4, C3H8, and C3H6 on both powdery and shaped ZIF-8 can be well described by the Langmuir equation.展开更多
The goals pursued by the Belt and Road Initiative(BRI)and the role played by international transportation on the development of cross-border trade suggest a focused review of issues dealing with taxation of transporta...The goals pursued by the Belt and Road Initiative(BRI)and the role played by international transportation on the development of cross-border trade suggest a focused review of issues dealing with taxation of transportation income derived from the operation of ships,railways and trucks in international traffic.This article covers an analysis of some of the treaties concluded by certain BRI jurisdictions and the possible ways of improvement of the tax regime applicable to taxation of international transportation either through international administrative cooperation or treaty legislation.展开更多
文摘Abstract: The current method to solve the problem of active suspension control for a vehicle is often dealt with a quarter-car or half-car model. But it is not enough to use this kind of model for practical applications. In this paper, based on considering the influence of factors such as, seat and passengers, a MDOF(multi-degree-of-freedom) model describing the vehicle motion is set up. The MODF model, which is 8DOF of four independent suspensions and four wheel tracks, is more applicable by comparison of its analysis result with some conventional vehicle models. Therefore, it is more suitable to use the 8DOF full-car model than a conventional 4DOF half-car model in the active control design for car vibration. Based on the derived 8DOF model, a controller is designed by using LQ (linear quadratic ) control theory, and the appropriate control scheme is selected by testing various performance indexes. Computer simulation is carried out for a passenger car running on a road with step disturbance and random road disturbance expressed by Power Spectral Density (PSD). Vibrations corresponding to ride comfort are derived under the foregoing road disturbances. The response results for uncontrolled and controlled system are compared. The response of vehicle vibration is greatly suppressed and quickly damped, which testifies the effect of the active suspension. The results achieved for various controllers are compared to investigate the influence of different control schemes on the control effect.
文摘This paper presents a MDOF (multi-degree-of-freedom) model to describe the vehicle motion, considering influences of factors such as, seat and passengers. The model is four-independent-suspension and four-wheel-track with 8DOF, and has proved more appropriate compared with some conventional vehicle models. Based on the derived 8DOF model, a controller for this model is designed by the use of H∞ control theory, Furthermore the appropriate control scheme is selected by testing various performance indexes. The study shows that satisfying results can be obtained by using an appropriate vehicle model, even if a low order controller and a general control strategy are adopted.
基金provided by the United States Agency for International Development under grant number 3FS-G-11-00002 to the Center for International Forestry Research,entitled the Nyimba Forest Projectprovided by The University of British Columbia
文摘Background：Information on above-ground biomass（AGB） is important for managing forest resource use at local levels,land management planning at regional levels,and carbon emissions reporting at national and international levels.In many tropical developing countries,this information may be unreliable or at a scale too coarse for use at local levels.There is a vital need to provide estimates of AGB with quantifiable uncertainty that can facilitate land use management and policy development improvements.Model-based methods provide an efficient framework to estimate AGB.Methods：Using National Forest Inventory（NFI） data for a^1,000,000 ha study area in the miombo ecoregion,Zambia,we estimated AGB using predicted canopy cover,environmental data,disturbance data,and Landsat 8 OLI satellite imagery.We assessed different combinations of these datasets using three models,a semiparametric generalized additive model（GAM） and two nonlinear models（sigmoidal and exponential）,employing a genetic algorithm for variable selection that minimized root mean square prediction error（RMSPE）,calculated through cross-validation.We compared model fit statistics to a null model as a baseline estimation method.Using bootstrap resampling methods,we calculated 95% confidence intervals for each model and compared results to a simple estimate of mean AGB from the NFI ground plot data.Results：Canopy cover,soil moisture,and vegetation indices were consistently selected as predictor variables.The sigmoidal model and the GAM performed similarly;for both models the RMSPE was -36.8 tonnes per hectare（i.e.,57% of the mean）.However,the sigmoidal model was approximately 30% more efficient than the GAM,assessed using bootstrapped variance estimates relative to a null model.After selecting the sigmoidal model,we estimated total AGB for the study area at 64,526,209 tonnes（＋/- 477,730）,with a confidence interval 20 times more precise than a simple designbased estimate.Conclusions：Our findings demonstrate that NFI data may be combined with freely available satellite imagery and soils data to estimate total AGB with quantifiable uncertainty,while also providing spatially explicit AGB maps useful for management,planning,and reporting purposes.
基金Supported by the National Natural Science Foundation of China(21176010,21476009,21406007,and U1462104)
文摘Zeolitic imidazolate framework-8(ZIF-8) was prepared through a solve-thermal reaction method and then shaped using different additives. The in fluence of the shaping conditions on the microstructure of the shaped samples was characterized by the XRD, BET, and SEM techniques. The results demonstrate that the compressive strength of the various shaped tablets is greatly increased and capable of meeting the industrial requirements compared to the unshaped ZIF-8 and that the loss rate of speci fic surface areas was maintained at 10% after the addition of 10%(by mass) binder and 10%(by mass) solvent. The adsorption isotherms of CO2, CH4, C3H8, and C3H6 on powdery ZIF-8and the shaped tablets(T-shaped ZIF-8, C-shaped ZIF-8, and N-shaped ZIF-8) were determined through volumetric measurements under different pressures and temperatures(298.2, 323.2, and 348.2 K). The adsorption capacities of the gases on both the ZIF-8 powder and the shaped tablets follow the order C3H6 N C3H8N CO2 N CH4. Furthermore,the results show that the adsorption capacities of the gases on the shaped tablets are lower by approximately 10%–20% than those on the powdery ZIF-8. In fact, the adsorption equilibrium isotherms for CO2, CH4, C3H8, and C3H6 on both powdery and shaped ZIF-8 can be well described by the Langmuir equation.
文摘The goals pursued by the Belt and Road Initiative(BRI)and the role played by international transportation on the development of cross-border trade suggest a focused review of issues dealing with taxation of transportation income derived from the operation of ships,railways and trucks in international traffic.This article covers an analysis of some of the treaties concluded by certain BRI jurisdictions and the possible ways of improvement of the tax regime applicable to taxation of international transportation either through international administrative cooperation or treaty legislation.
