Objective Clinical medical record data associated with hepatitis B-related acute-on-chronic liver failure(HBV-ACLF)generally have small sample sizes and a class imbalance.However,most machine learning models are desig...Objective Clinical medical record data associated with hepatitis B-related acute-on-chronic liver failure(HBV-ACLF)generally have small sample sizes and a class imbalance.However,most machine learning models are designed based on balanced data and lack interpretability.This study aimed to propose a traditional Chinese medicine(TCM)diagnostic model for HBV-ACLF based on the TCM syndrome differentiation and treatment theory,which is clinically interpretable and highly accurate.Methods We collected medical records from 261 patients diagnosed with HBV-ACLF,including three syndromes:Yang jaundice(214 cases),Yang-Yin jaundice(41 cases),and Yin jaundice(6 cases).To avoid overfitting of the machine learning model,we excluded the cases of Yin jaundice.After data standardization and cleaning,we obtained 255 relevant medical records of Yang jaundice and Yang-Yin jaundice.To address the class imbalance issue,we employed the oversampling method and five machine learning methods,including logistic regression(LR),support vector machine(SVM),decision tree(DT),random forest(RF),and extreme gradient boosting(XGBoost)to construct the syndrome diagnosis models.This study used precision,F1 score,the area under the receiver operating characteristic(ROC)curve(AUC),and accuracy as model evaluation metrics.The model with the best classification performance was selected to extract the diagnostic rule,and its clinical significance was thoroughly analyzed.Furthermore,we proposed a novel multiple-round stable rule extraction(MRSRE)method to obtain a stable rule set of features that can exhibit the model’s clinical interpretability.Results The precision of the five machine learning models built using oversampled balanced data exceeded 0.90.Among these models,the accuracy of RF classification of syndrome types was 0.92,and the mean F1 scores of the two categories of Yang jaundice and Yang-Yin jaundice were 0.93 and 0.94,respectively.Additionally,the AUC was 0.98.The extraction rules of the RF syndrome differentiation model based on the MRSRE method revealed that the common features of Yang jaundice and Yang-Yin jaundice were wiry pulse,yellowing of the urine,skin,and eyes,normal tongue body,healthy sublingual vessel,nausea,oil loathing,and poor appetite.The main features of Yang jaundice were a red tongue body and thickened sublingual vessels,whereas those of Yang-Yin jaundice were a dark tongue body,pale white tongue body,white tongue coating,lack of strength,slippery pulse,light red tongue body,slimy tongue coating,and abdominal distension.This is aligned with the classifications made by TCM experts based on TCM syndrome differentiation and treatment theory.Conclusion Our model can be utilized for differentiating HBV-ACLF syndromes,which has the potential to be applied to generate other clinically interpretable models with high accuracy on clinical data characterized by small sample sizes and a class imbalance.展开更多
This paper presents two approaches for system-level simulation of force-balance accelerometers. The derivation of the system-level model is elaborated and simulation results are obtained from the implementation of tho...This paper presents two approaches for system-level simulation of force-balance accelerometers. The derivation of the system-level model is elaborated and simulation results are obtained from the implementation of those strategies on the fabricated silicon force-balance MEMS accelerometer. The mathematical model presented is implemented in VHDL- AMS and SIMULINK TM,respectively. The simulation results from the two approaches are compared and show a slight difference. Using VHDL-AMS is flexible,reusable,and more accurate. But there is not a mature solver developed for the language and this approach takes more time, while the simulation model can be easily built and quickly evaluated using SIMULINK.展开更多
A discrete time stochastic traffic assignment model is proposed. The model provides a discrete time description of the variations of flows on a road network during a day or a peak period. The congestion effect at li...A discrete time stochastic traffic assignment model is proposed. The model provides a discrete time description of the variations of flows on a road network during a day or a peak period. The congestion effect at links and link junctions are taken into account. The first in first out principle is enforced on all links at all periods of the day. A stochastic user equilibrium assignment is achieved when the tripmaker is unable to find better travel alternatives. A computational procedure is also presented.展开更多
This paper puts forward a rigorous approach for a sensitivity analysis of stochastic user equilibrium with the elastic demand (SUEED) model. First, proof is given for the existence of derivatives of output variables...This paper puts forward a rigorous approach for a sensitivity analysis of stochastic user equilibrium with the elastic demand (SUEED) model. First, proof is given for the existence of derivatives of output variables with respect to the perturbation parameters for the SUEED model. Then by taking advantage of the gradient-based method for sensitivity analysis of a general nonlinear program, detailed formulae are developed for calculating the derivatives of designed variables with respect to perturbation parameters at the equilibrium state of the SUEED model. This method is not only applicable for a sensitivity analysis of the logit-type SUEED problem, but also for the probit-type SUEED problem. The application of the proposed method in a numerical example shows that the proposed method can be used to approximate the equilibrium link flow solutions for both logit-type SUEED and probit-type SUEED problems when small perturbations are introduced in the input parameters.展开更多
Taking experimental path on disordering AuCuI(AAuCu8A4)composed of A Au8 and ACu4 stem alloy genes as an example, three discoveries and a method were presented. The ability of Au Cu I(AAu Cu8 A4)to keep structure ...Taking experimental path on disordering AuCuI(AAuCu8A4)composed of A Au8 and ACu4 stem alloy genes as an example, three discoveries and a method were presented. The ability of Au Cu I(AAu Cu8 A4)to keep structure stabilization against changing temperature is attributed to the fact that the AAu8 and ACu4 potential well depths greatly surpass their vibration energies, which leads to the subequilibrium of experimental path. A new atom movement mechanism of AuCuI(AAuACu84)to change structure for suiting variation in temperature is the resonance activating-synchro alternating of alloy genes, which leads to heterogeneous and successive subequilibrium transitions. There exists jumping order degree, which leads to the existence of jumping Tj-temperature and an unexpected so-called "retro-effect" about jumping temperature retrograde shift to lower temperatures upon the increasing heating rate. A set of subequilibrium holographic network path charts were obtained by the experimental mixed enthalpy path method.展开更多
To improve the energy utilization efficiency of internal combustion (IC) engine, exergy analysis was conducted on a passenger car gasoline engine. According to the thermodynamic theory of IC engine, in-cylinder exer...To improve the energy utilization efficiency of internal combustion (IC) engine, exergy analysis was conducted on a passenger car gasoline engine. According to the thermodynamic theory of IC engine, in-cylinder exergy balance model was built. The working processes of gasoline engine were simulated by using the GT-power. In this way, the required parameters were calculated and then gasoline engine exergy balance was obtained by programming on computer. On this basis, the influences of various parameters on exergy balance were analyzed. Results show that, the proportions of various forms of exergy in gasoline engine from high to low are irreversible loss, effective work, exhaust gas exergy and heat transfer exergy. Effective exergy proportion fluctuates with cylinder volumetric efficiency at full load, while it always increases with break mean effective pressure (BMEP) at part load. Exhaust gas exergy proportion is more sensitive to speed, and it increases with speed increasing except at the highest speed. The lower proportion of heat transfer exergy appears at high speed and high load. Irreversible loss is mainly influenced by load. At part load, higher BMEP results in lower proportion of irreversible loss; at full load, the proportion of irreversible loss changes little except at the highest speed.展开更多
With the increase of mining depth,the effect of rock burst on coal mining is becoming more and more obvious and the rock burst mechanism becomes more and more complicated.Scholars from many countries had put forward d...With the increase of mining depth,the effect of rock burst on coal mining is becoming more and more obvious and the rock burst mechanism becomes more and more complicated.Scholars from many countries had put forward different mechanisms,but no one gave a reasonable explanation to the mechanism of rock burst.In this paper,based on the energy theories,we studied the energy limit equilibrium(ELE) of coal mine rock burst The coal seam with rock burst is divided into energy limit equilibrium zone(ELEZ)(A) and elastic zone(B);we also determined the position where the rock burst occurs,including the roof and floor of coal seams;in addition,we derived the limit width of ELEZ and the mathematic relationship between the limit width and occurrence mechanism of rock burst:the energy difference function(EDF),w(x) = w_j - w_p,because first-order derivative w'(x),is less than 0.So EDF is a monotonically decreasing function.The graph of the energy difference function was also determined, through which we analysed the occurrence mechanism of rock burst.展开更多
The SKS furnace is a horizontal cylindrical reactor similar to a Noranda furnace,however,the oxygen enriched air isblown into the furnace from the bottom.Mechanism model of the SKS process was developed by analyzing t...The SKS furnace is a horizontal cylindrical reactor similar to a Noranda furnace,however,the oxygen enriched air isblown into the furnace from the bottom.Mechanism model of the SKS process was developed by analyzing the smeltingcharacteristics deeply.In our model,the furnace section from top to bottom is divided into seven functional layers,i.e.,gas layer,mineral decomposition transitioning layer,slag layer,slag formation transitioning layer,matte formation transitioning layer,weakoxidizing layer and strong oxidizing layer.The furnace along the length direction is divided into three functional regions,that is,reaction region,separation transitioning region and liquid phase separation and settling region.These layers or regions play differentroles in the model in describing the mechanism of the smelting process.The SKS smelting is at a multiphase non-steady equilibriumstate,and the oxygen and sulfur potentials change gradually in the length and cross directions.The smelting capacity of the SKSprocess could be raised through reasonably controlling the potential values in different layers and regions.展开更多
The internally balanced theory proposed by the Japanese researchers,solved the contradiction between adsorption ability and moving capability of the permanent magnetic adsorption mechanism.However,it still has some pr...The internally balanced theory proposed by the Japanese researchers,solved the contradiction between adsorption ability and moving capability of the permanent magnetic adsorption mechanism.However,it still has some problems when applied to wall climbing robots.This paper analyzes and improves this theory,and the improved internally balanced theory satisfies the requirements of the adsorption mechanism significantly.Finally,a practical prototype is proposed based on this method,and both the analysis using ANSYS and the experiment results justify the design validity.展开更多
For a single cylinder engine, the total unbalanced inertial forces occur in the engine block, which results in engine’s vibration and deteriorated noise. In order to eliminate the unbalanced forces, counterweight and...For a single cylinder engine, the total unbalanced inertial forces occur in the engine block, which results in engine’s vibration and deteriorated noise. In order to eliminate the unbalanced forces, counterweight and primary balance shaft should be attached to the cylinder block so that engine durability and ride comfortability may be further improved. Traditionally one third of connecting rod assembly’s mass is treated as reciprocating mass, and two thirds as rotating mass when designing balance mechanism. In this paper, a new method based on the multibody dynamics simulation is introduced to separate the reciprocating mass and rotating mass of connecting rod assembly. The model consists of crankshaft, connecting rod, piston and the simulation is performed subsequently. According to the simulation results of the main bearing loads, the reciprocating mass and rotating mass are separated. Finally a new balance mechanism is designed and simulation results show that it completely balances inertial forces to improve the engine’s noise vibration and harshness performance.展开更多
Because the normal operation of the engine is located near the equilibrium manifold, the method of equilibrium mani fold nonlinear dynamic modeling is adopted for turbofan engine more than the local train modeling. Th...Because the normal operation of the engine is located near the equilibrium manifold, the method of equilibrium mani fold nonlinear dynamic modeling is adopted for turbofan engine more than the local train modeling. The method studies the sys tem characteristics near the equilibrium manifold. The modeling method can be realized through dynamic and static twostep, and for the specific parameter modeling steps and algorithm are given. The output of the test data is compared with the model output through numerical simulation, to check the model with an additional set of test data. The simulation results show that the model has reached the requirements of engineering accuracy.展开更多
Considerable evidence that the soil organic matter (OM) level in agricultural soils will gradually over time reach an equilibrium state under certain bioclimatic conditions and for certain cropping systems has been ...Considerable evidence that the soil organic matter (OM) level in agricultural soils will gradually over time reach an equilibrium state under certain bioclimatic conditions and for certain cropping systems has been accumulating. Although models or long-term experiments have been used, this research used physical fractionation procedure to attain an soil OM equilibrium value. To obtain soil OM equilibrium values in the heavy fraction, typical soils from three long-term field experiments at Fengqiu and Yingtan State Key Agro-Ecological Experimental Stations in China were studied using a simple density fractionation procedure and employing the Langmuir equation. Results for the fluvo-aquic soil with organic fertilizer treatments indicated that the soil OM equilibrium value in the heavy fraction was twofold more than that in the inorganic treatments; however, for the paddy soil developed on red soil the OM equilibrium value in the heavy fraction for both treatments was almost identical. It suggested that for fiuvo-aquic soils the increased potential of OM for the heavy fraction in the long run was larger for the organic than the inorganic fertilizer applications, whereas for paddy soils developed on red soils under the same conditions the present OM content in the heavy fraction was at or close to this equilibrium level for all treatments, and increased potential was very limited.展开更多
Hash chain and its generalization—Multi-Dimensional Hash Chain (MDHC) have been widely used in the design of micropayment due to its simplicity and efficiency. In this letter, a more efficient variant of MDHC, called...Hash chain and its generalization—Multi-Dimensional Hash Chain (MDHC) have been widely used in the design of micropayment due to its simplicity and efficiency. In this letter, a more efficient variant of MDHC, called WMDHC, which endows in the structure of MDHC a weight value for each hash value through a well-defined mapping, is proposed. The average hash operation number of WMDHC is log(2 m / t ),which is better than log( m )of MDHC when the parameter t is typically suggested as t = 7.展开更多
Traffic assignment has been recognized as one of the key technologies in supporting transportation planning and operations.To better address the perfectly rational issue of the expected utility theory(EUT)and the over...Traffic assignment has been recognized as one of the key technologies in supporting transportation planning and operations.To better address the perfectly rational issue of the expected utility theory(EUT)and the overlapping path issue of the multinomial logit(MNL)model that are involved in the traffic assignment process,this paper proposes a cumulative prospect value(CPV)-based generalized nested logit(GNL)stochastic user equilibrium(SUE)model.The proposed model uses CPV to replace the utility value as the path performance within the GNL model framework.An equivalent mathematical model is provided for the proposed CPV-based GNL SUE model,which is solved by the method of successive averages(MSA).The existence and equivalence of the solution are also proved for the equivalent model.To demonstrate the performance of the proposed CPV-based GNL SUE model,three road networks are selected in the empirical test.The results show that the proposed model can jointly deal with the perfectly rational issue and the overlapping path issue,and additionally,the proposed model is shown to be applicable for large road networks.展开更多
This paper takes stock of theoretical economic analyses of overcapacity,reveals the factors that induce actual capacity to deviate from market equilibrium, examines market-based mechanisms to resolve overcapacity, and...This paper takes stock of theoretical economic analyses of overcapacity,reveals the factors that induce actual capacity to deviate from market equilibrium, examines market-based mechanisms to resolve overcapacity, and identifies long-term mechanisms and assurances for market-based solutions to overcapacity. Given the limitations of market mechanism and the government's role, neither the market nor the government is able to resolve the problem of overcapacity on its own. In resolving overcapacity, market and the government should play their respective roles rather than replace one another. While the market is a dominant force in regulating capacity and achieving supply and demand equilibrium, the government should provide institutional assurances for effective market operation. Market-based solutions to overcapacity require the government to provide institutional assurances and create a system where market entities decide to enter and exit the market under effective restraints and incentives with a clear boundary.展开更多
Knowledge of the equilibrium bed-concentration is vital to mathematic a l modeling of the river-bed deformation associated with suspended load but prev i ous investigations only dealt with the reference concentration ...Knowledge of the equilibrium bed-concentration is vital to mathematic a l modeling of the river-bed deformation associated with suspended load but prev i ous investigations only dealt with the reference concentration of uniform sedime nt because of difficulties in observation of the bed-concentration. This work i s a first attempt to develop a theoretical formula for the equilibrium bed-conce n tration of any fraction of nonuniform sediment defined at the bed-surface. The f ormula is based on a stochastic-mechanistic model for the exchange of nonunifor m sediment near the bed, and described as a function of incipient motion probabil ity, non-ceasing probability, pick-up probability, and the ratio of the averag e single-step continuous motion time to static time. Comparison of bed-concentra ti on calculated from the proposed formula with the measured data showed satisfacto ry agreement, indicating the present formula can be used for solving the differe ntial equation governing the motion of suspended load.展开更多
A customized combined methodology based on both 2D CFD (computational fluid dynamics) and lumped parameters numerical modeling, useful for simulating the hydraulic behavior of orbit annular machines, has been develo...A customized combined methodology based on both 2D CFD (computational fluid dynamics) and lumped parameters numerical modeling, useful for simulating the hydraulic behavior of orbit annular machines, has been developed and here presented. More in details, the predictive capabilities of this CAE (computer-aided engineering) tool can be applied for the study of both roller and gerotor architectures and considering both pumping and motoring operating mode. First of all, an in-house developed 2D CFD methodology, based on the integration of the stationary form of the Reynolds equation for the determination of the pressure distribution inside the lateral clearances bounded by the sides of the stator-rotor group and the valve plate, as well as the internal manifold surface, is firstly presented and applied. The same computational procedure has been also involved for the investigation of the leakages through the clearance between the valve plate and the balancing ring. After that, a lumped and distributed parameters numerical model has been involved for the simulation of a typical orbit roller motor operation. In this case, particular care has been devoted to the modeling of the axial leakage clearances, adopting analytical interpolation functions deducted from the numerical results calculated applying the previously described 2D CFD methodology. Finally, the whole CAE approach has been validated by means of a comprehensive numerical versus experimental comparison, obtaining a general good accordance for the overall operating field of this particular type of hydraulic unit.展开更多
A discontinuity of magnetic circuits according to the end effect is generated in the permanent magnet linear synchronous motor (PMLSM). Due to the unbalanced back electro-motive force (EMF) and impedance produced,...A discontinuity of magnetic circuits according to the end effect is generated in the permanent magnet linear synchronous motor (PMLSM). Due to the unbalanced back electro-motive force (EMF) and impedance produced, unbalanced current is generated. The cireulatin8 current, which is caused by a decrease in the thrust, is generated by the unbalanced current. The optimal design of auxiliary-teeth at the end of the mover was carried out to solve the unbalance of phase by using design of experiment (DOE), and compared with the basic model through finite element analysis (FEA). As a result, the auxiliary-teeth model compensates for the decrease of thrust caused by the unbalanced phase. Also, this model is proven to reduce the detent force by the vibration and noise of the PMLSM and copper loss caused by the circulating current.展开更多
基金Key research project of Hunan Provincial Administration of Traditional Chinese Medicine(A2023048)Key Research Foundation of Education Bureau of Hunan Province,China(23A0273).
文摘Objective Clinical medical record data associated with hepatitis B-related acute-on-chronic liver failure(HBV-ACLF)generally have small sample sizes and a class imbalance.However,most machine learning models are designed based on balanced data and lack interpretability.This study aimed to propose a traditional Chinese medicine(TCM)diagnostic model for HBV-ACLF based on the TCM syndrome differentiation and treatment theory,which is clinically interpretable and highly accurate.Methods We collected medical records from 261 patients diagnosed with HBV-ACLF,including three syndromes:Yang jaundice(214 cases),Yang-Yin jaundice(41 cases),and Yin jaundice(6 cases).To avoid overfitting of the machine learning model,we excluded the cases of Yin jaundice.After data standardization and cleaning,we obtained 255 relevant medical records of Yang jaundice and Yang-Yin jaundice.To address the class imbalance issue,we employed the oversampling method and five machine learning methods,including logistic regression(LR),support vector machine(SVM),decision tree(DT),random forest(RF),and extreme gradient boosting(XGBoost)to construct the syndrome diagnosis models.This study used precision,F1 score,the area under the receiver operating characteristic(ROC)curve(AUC),and accuracy as model evaluation metrics.The model with the best classification performance was selected to extract the diagnostic rule,and its clinical significance was thoroughly analyzed.Furthermore,we proposed a novel multiple-round stable rule extraction(MRSRE)method to obtain a stable rule set of features that can exhibit the model’s clinical interpretability.Results The precision of the five machine learning models built using oversampled balanced data exceeded 0.90.Among these models,the accuracy of RF classification of syndrome types was 0.92,and the mean F1 scores of the two categories of Yang jaundice and Yang-Yin jaundice were 0.93 and 0.94,respectively.Additionally,the AUC was 0.98.The extraction rules of the RF syndrome differentiation model based on the MRSRE method revealed that the common features of Yang jaundice and Yang-Yin jaundice were wiry pulse,yellowing of the urine,skin,and eyes,normal tongue body,healthy sublingual vessel,nausea,oil loathing,and poor appetite.The main features of Yang jaundice were a red tongue body and thickened sublingual vessels,whereas those of Yang-Yin jaundice were a dark tongue body,pale white tongue body,white tongue coating,lack of strength,slippery pulse,light red tongue body,slimy tongue coating,and abdominal distension.This is aligned with the classifications made by TCM experts based on TCM syndrome differentiation and treatment theory.Conclusion Our model can be utilized for differentiating HBV-ACLF syndromes,which has the potential to be applied to generate other clinically interpretable models with high accuracy on clinical data characterized by small sample sizes and a class imbalance.
文摘This paper presents two approaches for system-level simulation of force-balance accelerometers. The derivation of the system-level model is elaborated and simulation results are obtained from the implementation of those strategies on the fabricated silicon force-balance MEMS accelerometer. The mathematical model presented is implemented in VHDL- AMS and SIMULINK TM,respectively. The simulation results from the two approaches are compared and show a slight difference. Using VHDL-AMS is flexible,reusable,and more accurate. But there is not a mature solver developed for the language and this approach takes more time, while the simulation model can be easily built and quickly evaluated using SIMULINK.
文摘A discrete time stochastic traffic assignment model is proposed. The model provides a discrete time description of the variations of flows on a road network during a day or a peak period. The congestion effect at links and link junctions are taken into account. The first in first out principle is enforced on all links at all periods of the day. A stochastic user equilibrium assignment is achieved when the tripmaker is unable to find better travel alternatives. A computational procedure is also presented.
基金The Scientific Innovation Research of College Graduates in Jiangsu Province(No.CXLX13_110)the Young Scientists Fund of National Natural Science Foundation of China(No.51408253)the Young Scientists Fund of Huaiyin Institute of Technology(No.491713328)
文摘This paper puts forward a rigorous approach for a sensitivity analysis of stochastic user equilibrium with the elastic demand (SUEED) model. First, proof is given for the existence of derivatives of output variables with respect to the perturbation parameters for the SUEED model. Then by taking advantage of the gradient-based method for sensitivity analysis of a general nonlinear program, detailed formulae are developed for calculating the derivatives of designed variables with respect to perturbation parameters at the equilibrium state of the SUEED model. This method is not only applicable for a sensitivity analysis of the logit-type SUEED problem, but also for the probit-type SUEED problem. The application of the proposed method in a numerical example shows that the proposed method can be used to approximate the equilibrium link flow solutions for both logit-type SUEED and probit-type SUEED problems when small perturbations are introduced in the input parameters.
基金Project(51071181)supported by the National Natural Science Foundation of ChinaProject(2013FJ4043)supported by the Natural Science Foundation of Hunan Province,China
文摘Taking experimental path on disordering AuCuI(AAuCu8A4)composed of A Au8 and ACu4 stem alloy genes as an example, three discoveries and a method were presented. The ability of Au Cu I(AAu Cu8 A4)to keep structure stabilization against changing temperature is attributed to the fact that the AAu8 and ACu4 potential well depths greatly surpass their vibration energies, which leads to the subequilibrium of experimental path. A new atom movement mechanism of AuCuI(AAuACu84)to change structure for suiting variation in temperature is the resonance activating-synchro alternating of alloy genes, which leads to heterogeneous and successive subequilibrium transitions. There exists jumping order degree, which leads to the existence of jumping Tj-temperature and an unexpected so-called "retro-effect" about jumping temperature retrograde shift to lower temperatures upon the increasing heating rate. A set of subequilibrium holographic network path charts were obtained by the experimental mixed enthalpy path method.
基金Foundation item: Project(2011CB707201) supported by the National Basic Research Program of China Project(10JJ5058) supported by the Natural Science Foundation of Hunan Province, China
文摘To improve the energy utilization efficiency of internal combustion (IC) engine, exergy analysis was conducted on a passenger car gasoline engine. According to the thermodynamic theory of IC engine, in-cylinder exergy balance model was built. The working processes of gasoline engine were simulated by using the GT-power. In this way, the required parameters were calculated and then gasoline engine exergy balance was obtained by programming on computer. On this basis, the influences of various parameters on exergy balance were analyzed. Results show that, the proportions of various forms of exergy in gasoline engine from high to low are irreversible loss, effective work, exhaust gas exergy and heat transfer exergy. Effective exergy proportion fluctuates with cylinder volumetric efficiency at full load, while it always increases with break mean effective pressure (BMEP) at part load. Exhaust gas exergy proportion is more sensitive to speed, and it increases with speed increasing except at the highest speed. The lower proportion of heat transfer exergy appears at high speed and high load. Irreversible loss is mainly influenced by load. At part load, higher BMEP results in lower proportion of irreversible loss; at full load, the proportion of irreversible loss changes little except at the highest speed.
基金Financial support for this project,provided by the Key Basic Research Program of China(No.2006CB202200)the National Major Project of Ministry of Education(No.304005)the Program for Changjiang Scholars and Innovative Research Team in University of China(No.IRT0656)
文摘With the increase of mining depth,the effect of rock burst on coal mining is becoming more and more obvious and the rock burst mechanism becomes more and more complicated.Scholars from many countries had put forward different mechanisms,but no one gave a reasonable explanation to the mechanism of rock burst.In this paper,based on the energy theories,we studied the energy limit equilibrium(ELE) of coal mine rock burst The coal seam with rock burst is divided into energy limit equilibrium zone(ELEZ)(A) and elastic zone(B);we also determined the position where the rock burst occurs,including the roof and floor of coal seams;in addition,we derived the limit width of ELEZ and the mathematic relationship between the limit width and occurrence mechanism of rock burst:the energy difference function(EDF),w(x) = w_j - w_p,because first-order derivative w'(x),is less than 0.So EDF is a monotonically decreasing function.The graph of the energy difference function was also determined, through which we analysed the occurrence mechanism of rock burst.
基金Project(51620105013)supported by the National Natural Science Foundation of China
文摘The SKS furnace is a horizontal cylindrical reactor similar to a Noranda furnace,however,the oxygen enriched air isblown into the furnace from the bottom.Mechanism model of the SKS process was developed by analyzing the smeltingcharacteristics deeply.In our model,the furnace section from top to bottom is divided into seven functional layers,i.e.,gas layer,mineral decomposition transitioning layer,slag layer,slag formation transitioning layer,matte formation transitioning layer,weakoxidizing layer and strong oxidizing layer.The furnace along the length direction is divided into three functional regions,that is,reaction region,separation transitioning region and liquid phase separation and settling region.These layers or regions play differentroles in the model in describing the mechanism of the smelting process.The SKS smelting is at a multiphase non-steady equilibriumstate,and the oxygen and sulfur potentials change gradually in the length and cross directions.The smelting capacity of the SKSprocess could be raised through reasonably controlling the potential values in different layers and regions.
文摘The internally balanced theory proposed by the Japanese researchers,solved the contradiction between adsorption ability and moving capability of the permanent magnetic adsorption mechanism.However,it still has some problems when applied to wall climbing robots.This paper analyzes and improves this theory,and the improved internally balanced theory satisfies the requirements of the adsorption mechanism significantly.Finally,a practical prototype is proposed based on this method,and both the analysis using ANSYS and the experiment results justify the design validity.
基金Supported by National Natural Science Foundation of China (No50575203)
文摘For a single cylinder engine, the total unbalanced inertial forces occur in the engine block, which results in engine’s vibration and deteriorated noise. In order to eliminate the unbalanced forces, counterweight and primary balance shaft should be attached to the cylinder block so that engine durability and ride comfortability may be further improved. Traditionally one third of connecting rod assembly’s mass is treated as reciprocating mass, and two thirds as rotating mass when designing balance mechanism. In this paper, a new method based on the multibody dynamics simulation is introduced to separate the reciprocating mass and rotating mass of connecting rod assembly. The model consists of crankshaft, connecting rod, piston and the simulation is performed subsequently. According to the simulation results of the main bearing loads, the reciprocating mass and rotating mass are separated. Finally a new balance mechanism is designed and simulation results show that it completely balances inertial forces to improve the engine’s noise vibration and harshness performance.
文摘Because the normal operation of the engine is located near the equilibrium manifold, the method of equilibrium mani fold nonlinear dynamic modeling is adopted for turbofan engine more than the local train modeling. The method studies the sys tem characteristics near the equilibrium manifold. The modeling method can be realized through dynamic and static twostep, and for the specific parameter modeling steps and algorithm are given. The output of the test data is compared with the model output through numerical simulation, to check the model with an additional set of test data. The simulation results show that the model has reached the requirements of engineering accuracy.
基金Project supported by the National Science Fund for Distinguished Young Scholars of China (No. 40125004) the Knowledge Innovation Program of the Chinese Academy of Sciences (No. KZCX1-SW-01-05).
文摘Considerable evidence that the soil organic matter (OM) level in agricultural soils will gradually over time reach an equilibrium state under certain bioclimatic conditions and for certain cropping systems has been accumulating. Although models or long-term experiments have been used, this research used physical fractionation procedure to attain an soil OM equilibrium value. To obtain soil OM equilibrium values in the heavy fraction, typical soils from three long-term field experiments at Fengqiu and Yingtan State Key Agro-Ecological Experimental Stations in China were studied using a simple density fractionation procedure and employing the Langmuir equation. Results for the fluvo-aquic soil with organic fertilizer treatments indicated that the soil OM equilibrium value in the heavy fraction was twofold more than that in the inorganic treatments; however, for the paddy soil developed on red soil the OM equilibrium value in the heavy fraction for both treatments was almost identical. It suggested that for fiuvo-aquic soils the increased potential of OM for the heavy fraction in the long run was larger for the organic than the inorganic fertilizer applications, whereas for paddy soils developed on red soils under the same conditions the present OM content in the heavy fraction was at or close to this equilibrium level for all treatments, and increased potential was very limited.
基金Supported by the National Natural Science Foundation of China (No.60373041 & 90104034) and the Research Foundation for Outstanding Young Teachers, China University of Geosciences (Wuhan).
文摘Hash chain and its generalization—Multi-Dimensional Hash Chain (MDHC) have been widely used in the design of micropayment due to its simplicity and efficiency. In this letter, a more efficient variant of MDHC, called WMDHC, which endows in the structure of MDHC a weight value for each hash value through a well-defined mapping, is proposed. The average hash operation number of WMDHC is log(2 m / t ),which is better than log( m )of MDHC when the parameter t is typically suggested as t = 7.
基金Project(KYLX16_0271)supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China。
文摘Traffic assignment has been recognized as one of the key technologies in supporting transportation planning and operations.To better address the perfectly rational issue of the expected utility theory(EUT)and the overlapping path issue of the multinomial logit(MNL)model that are involved in the traffic assignment process,this paper proposes a cumulative prospect value(CPV)-based generalized nested logit(GNL)stochastic user equilibrium(SUE)model.The proposed model uses CPV to replace the utility value as the path performance within the GNL model framework.An equivalent mathematical model is provided for the proposed CPV-based GNL SUE model,which is solved by the method of successive averages(MSA).The existence and equivalence of the solution are also proved for the equivalent model.To demonstrate the performance of the proposed CPV-based GNL SUE model,three road networks are selected in the empirical test.The results show that the proposed model can jointly deal with the perfectly rational issue and the overlapping path issue,and additionally,the proposed model is shown to be applicable for large road networks.
文摘This paper takes stock of theoretical economic analyses of overcapacity,reveals the factors that induce actual capacity to deviate from market equilibrium, examines market-based mechanisms to resolve overcapacity, and identifies long-term mechanisms and assurances for market-based solutions to overcapacity. Given the limitations of market mechanism and the government's role, neither the market nor the government is able to resolve the problem of overcapacity on its own. In resolving overcapacity, market and the government should play their respective roles rather than replace one another. While the market is a dominant force in regulating capacity and achieving supply and demand equilibrium, the government should provide institutional assurances for effective market operation. Market-based solutions to overcapacity require the government to provide institutional assurances and create a system where market entities decide to enter and exit the market under effective restraints and incentives with a clear boundary.
文摘Knowledge of the equilibrium bed-concentration is vital to mathematic a l modeling of the river-bed deformation associated with suspended load but prev i ous investigations only dealt with the reference concentration of uniform sedime nt because of difficulties in observation of the bed-concentration. This work i s a first attempt to develop a theoretical formula for the equilibrium bed-conce n tration of any fraction of nonuniform sediment defined at the bed-surface. The f ormula is based on a stochastic-mechanistic model for the exchange of nonunifor m sediment near the bed, and described as a function of incipient motion probabil ity, non-ceasing probability, pick-up probability, and the ratio of the averag e single-step continuous motion time to static time. Comparison of bed-concentra ti on calculated from the proposed formula with the measured data showed satisfacto ry agreement, indicating the present formula can be used for solving the differe ntial equation governing the motion of suspended load.
文摘A customized combined methodology based on both 2D CFD (computational fluid dynamics) and lumped parameters numerical modeling, useful for simulating the hydraulic behavior of orbit annular machines, has been developed and here presented. More in details, the predictive capabilities of this CAE (computer-aided engineering) tool can be applied for the study of both roller and gerotor architectures and considering both pumping and motoring operating mode. First of all, an in-house developed 2D CFD methodology, based on the integration of the stationary form of the Reynolds equation for the determination of the pressure distribution inside the lateral clearances bounded by the sides of the stator-rotor group and the valve plate, as well as the internal manifold surface, is firstly presented and applied. The same computational procedure has been also involved for the investigation of the leakages through the clearance between the valve plate and the balancing ring. After that, a lumped and distributed parameters numerical model has been involved for the simulation of a typical orbit roller motor operation. In this case, particular care has been devoted to the modeling of the axial leakage clearances, adopting analytical interpolation functions deducted from the numerical results calculated applying the previously described 2D CFD methodology. Finally, the whole CAE approach has been validated by means of a comprehensive numerical versus experimental comparison, obtaining a general good accordance for the overall operating field of this particular type of hydraulic unit.
基金supported by the Second Stage of Brain Korea 21 Projects and Changwon National University in 2009-2010
文摘A discontinuity of magnetic circuits according to the end effect is generated in the permanent magnet linear synchronous motor (PMLSM). Due to the unbalanced back electro-motive force (EMF) and impedance produced, unbalanced current is generated. The cireulatin8 current, which is caused by a decrease in the thrust, is generated by the unbalanced current. The optimal design of auxiliary-teeth at the end of the mover was carried out to solve the unbalance of phase by using design of experiment (DOE), and compared with the basic model through finite element analysis (FEA). As a result, the auxiliary-teeth model compensates for the decrease of thrust caused by the unbalanced phase. Also, this model is proven to reduce the detent force by the vibration and noise of the PMLSM and copper loss caused by the circulating current.