Abstract:Along with the progress of fine-graining, the rule of particle size distribution in fine-grained tailings becomes increasingly significant as it has an important influence on tailings' macro mechanical properties and stability. In this paper, we analyzed 82 tailing samples with the sieving and the settlement methods, and set up a Weibull function model for fine-grained tailings. The experimental results show that the number of fine particle is far more than that of coarse particle, and this distribution character can be described and speculated by Weibull distribution. Weibull distribution could be regarded as a fractal model to a certain extent and it considers the change of crushing rate that tradition fractal model doesn't consider. In the process of crushing, the peak of probability density distribution shifts towards the direction of fine particles, and this explains how the distribution character of fine-grained tailings forms. It's hoped that the research findings provide references for granularity theory and ore grinding process.

Abstract:RFD (reverse flow divert) set is a kind of maintenance-free delivery system driving by compress-air. It intermittently discharges through its delivery pipe. RFD set has no moving part, and its optimized design is critical to efficient and stable operation. The deficiencies in optimization of traditional enumeration algorithm and the marginal utility method were indicated. Then, as a mainly point of the paper, using the genetic algorithm (GA) to solve the multi-objective multidimensional optimization problem was discussed. By comparing the results of the three optimization methods, the superiority of GA can be drawn. Based on the industrial needs for flow and head, a serialization design of RFD was done by using GA and the relationships of the structural parameters and the operational parameters were analyzed. And the conversion relationships of RFD average flow in different densities and viscosities were provided. The promoted approach will be benefit for the RFD set design in industry.

Abstract:The reasonable design of the vehicle front-end structure stiffness can effectively improve the performance of pedestrian protection. The optimal design of the bumper absorber was completed by structure optimization, and the stiffness curve was the object. The crash test of the bumper of a passenger car was conducted. Meanwhile the finite element model of the collision between the bumper and rigid pillar was established. The accuracy of the finite element model was verified through comparison between the simulation and test results. In order to make the stiffness curve of the bumper area be close to the ideal stiffness curve, the design variables were the geometric shape and the material stiffness of the absorber. The object was to minimize the area between the ideal stiffness curve and the bumper stiffness curve. Adaptive response surface method was used to optimize the absorber. The result shows that the bumper stiffness curve of the optimized material stiffness and geometric shape is consistent with the ideal stiffness curve and meets the requirement of the pedestrian protection.

Abstract:Intelligent substation is the core part of smart grid, and the operating condition of its secondary equipment concerns the security and the stability of the power system. For the features of intricate failure reasons and incomplete operating status information of intelligent substation secondary equipment, we established a hierarchical model and an index system to assess its operating condition. Grey clustering algorithm was introduced to classify the conditions and the whitening weight function of grey was established first, and then the analytic hierarchy process was used to calculate the weight of status indicators. Finally, the analytic hierarchy process and grey clustering algorithm was combined to qualitatively and quantitatively assess the operating condition. Practical case study verifies the effectiveness and feasibility of this method and it provides a theoretical basis for the secondary-equipment-condition-based maintenance work.

Abstract:For the fact that the ship propeller has a strict requirement for the running accuracy of the water lubricated rubber bearing system (WLRBS), a finite element contact model of the WLRBS was established. The effects of the rubber liner's hardness and thickness on the runout of the WLRBS with straight or spiral grooves were analyzed, and a way of controlling the runout was put forward. The research results indicate that the value of the runout increases with the decrease of the rubber hardness, while increases with the increase of the rubber thickness. And the runout of the shaft is relatively small when the hardness varies between 85~95 shore A. The thickness of rubber should be designed as thin as possible with ensuring the groove dimension. Besides, the runout of the WLRBS with spiral grooves is smaller than that with straight grooves. Therefore, scientific and reasonable design of the geometric structure and the hardness of the rubber liner can significantly reduce the value of the runout and improve the running accuracy.

Abstract:The quantitative investigation of as-cast, as solution and ageing heat-treated microstructures of a second generation Ni-based single crystal DD11 was carried out through OM and SEM. The stress rupture properties of the alloys which had been first ageing treated under 1 100℃/140 MPa and 980℃/250 MPa respectively were also tested. The results indicate that (γ+γ') eutectic is almost dissolved when DD11 is under solution treatment of 1 320℃/6 h. And the degree of solidification segregation significantly decreases, and the alloy exhibits uniform microstructure. When the first ageing treatment temperature is lower than 1 160℃, the shape of γ' phase is cubic. But the shape transforms to sphericity when the aging temperature is higher than 1 180℃, the width of γ phase channel greatly increases, and fine γ' phase precipitates in the γ phase channel. With the increase of the first ageing treatment temperature, the stress rupture live of the alloy increases first and then decreases. The stress rupture properties are closely related to the size, the volume fraction and the morphology of γ' phase.

Abstract:A large amount of ferronickel slag containing high MgO composition is discharged every year in China, but it has not found an efficient method to utilize the slag so far. We investigated the feasibility and the effect of using ferronickel slag containing high MgO composition as an active mixed material on the basis of analyzing its composition and performance. The results show that the content of amorphous mineral in the slag is 88.1%. The content of MgO reaches 27.07% and it mainly exists as enstatite and hortonolite. The slag's activity and its dosage used in the cement are affected by its specific surface area. As an active mixing material, its specific surface area should be no less than 454.6 m²/kg. The bigger the specific surface area of the slag is, the higher the active index is, and the larger the dosage in the cement is. The autoclave soundness of the cement mixed with high-MgO ferronickel slag is qualified. Even if the mixing dosage of the slag with specific surface area of 842.9 m²/kg is up to 50%, the autoclave expansion rate of the new cement is only 0.11%, which is significantly lower than 0.5% as required by GB750-92. Therefore, ferronickel slag containing high MgO composition can be used as an active mixed material.

Abstract:Based on the fact that the uniaxial compressive strengths (UCS) of rock are normally distributed random variables, we first used mathematical statistics to analyze the scattering and the interval parameters of UCS of rock samples, then deduced a theoretical calculation formula about interval parameters of UCS of rock spamles and analyzed the relationship between the sample size and the mean of uniaxial compressive strength, the sample standard deviation, the confidence interval for population mean, and the confidence interval for population standard deviation of UCS of rock samples, and finally employed the previous test data to verify and analyze the interval parameters. The results show that the present single value method doesn't contain enough information and cannot guarantee the reliability of the comparison between tests data obtained under different test conditions. However, the interval estimation method can overcome the deficiency and can be used even if the sample size is small, but its confidence level will be lower (confidence interval width will be greater). When the sample size is small, the volatility of the sample standard deviation is one order of magnitude higher than that of the sample mean, the randomness and the discreteness of the sample standard deviation is greater, and the sample size for achieving stable convergence is larger. The confidence interval and the confidence level of UCS of rock samples are related to sample size, heterogeneity of rock sample, and randomness of rock strength distribution, etc.

Abstract:In order to reduce the time of data filtering processing in the adaptive control system for autom-otive headlights, a method of amplitude-limiting median filter is proposed in this paper, which is based on sliding median filtering algorithm and can follow the variation trend of signals through a way of compen-sation. The algorithm needs two steps to complete filtering. The data is amplitude-limited with compensation first, and then processed through sliding median filtering. This algorithm combines real-time of sliding median filtering method with the validity to filter the random interference of amplitude-limited filtering method, and it could smooth the graph more accurately. The simulation and actual test results show that the improved filtering method can filter interference in the data in real time and the processing time can be reduced by 62% compared with that of the sliding median filtering method. In addition, it can get a better result and the lag time of speed signal is shorter. Moreover, it has a high real-time performance and satisfies the requirement of system design.

Abstract:In this paper, an intelligent-video-analysis-based vehicle abnormal behavior detection method was presented to handle the real-time problem in vehicle abnormal behavior detection. When vehicle abnormal behavior occurs, vehicle position, velocity and moving direction change rapidly. To extract the changes of the three parameters mentioned above, the background subtraction approach was adapted to detect vehicles. Furthermore the meanshift algorithm was utilized to track the detected vehicles. Vehicle behavior decision can be concluded by weight fusion of the three parameters. To verify the proposed method, experiments on real videos were operated. Experimental results demonstrate that the proposed method can detect vehicle abnormal behavior effectively in real traffic scene.

Abstract:To study the effect of ventilation mode on indoor thermal environmental parameters in winter in cold zone, the realizable k-ε turbulent model of CFD was adopted to numerically analyze the airflow field, temperature field and thermal comfort of a residence in Lanzhou when the unsteady heat transfer through outerwalls was considered. Three types of ventilation modes were obtained on the condition that the indoor heating temperature was ensured and the indoor air quality was improved simultaneously. Comparing the indoor characteristics of airflow field and temperature of the three types of ventilation modes, we analyzed the thermal comfort in different rooms subsequently. And the thermal comfort results indicate that the indoor environment feels a little cold for all the three feasible ventilation modes.

Abstract:4-hydroxyphenylacetate decarboxylase (HPA) is a kind of glycyl radical enzymes (GREs), which catalyze the formation of p-cresol or skatole. It is characterized by a small subunit (HpdC), and shows unique properties that have not been observed in other GREs. Thus HPA decarboxylase is considered as a new kind of GRE. The existing researches show the importance of HpdC in the decarboxylase family, but its importance hasn't been experimentally verified. To elucidate the functions of HpdC, a series of over-expression plasmids for the hybrid decarboxylases were established and the corresponding encoded proteins were purified and analyzed. The final physio-chemical analysis and the enzyme activity test results prove that the small subunit is directly involved in the regulation of the enzymes' oligomeric state and activity.

Abstract:The research on the transport of fine particles in saturated porous media under elastic waves is complementary to the current study of particle migration in static multi-phases or steady-state seepage flow. Considering the influence of elastic waves on particle detachment-migration-capture process, we established a modified model of fine particle transport under elastic waves, and analyzed the changes of particle migration and physical properties in reservoir. Furthermore, the critical velocity of particle detachment from the pore surface under elastic waves was derived, which was found negatively related to the fluid viscosity and particle/pore-throat radius ratio, but positively related to the degree of matrix cementation, structural force, particle radius and density. It also shows the smaller the particle/pore-throat radius ratio is, the stronger the impact of wave imposing on particle detachments is. The model also considers the changes of flow rate under waves. When the detachment rate of fine particles increases, the retention rate of deposition would increase firstly and then decline with wave attenuation and time extension, and the retention rate of throat-blocking would rise. It demonstrates that the elastic wave not only leads to an enhancement in the capacity of particle detachment and suspension, but increases the possibilities of "bridge" blocking in micro throats. This study might be useful to the exploration on rock physical properties in petrophysics and industrial wave application.

Abstract:Gas collector pressure is an important parameter in the process of coking production, because the stable pressure directly affect gas quality, life of coke oven, coke quality and the production environment in coke oven. By cascading the inverse system of the gas collector pressure in coke oven identified by LS-SVM with the original one, we decoupled the system of gas collector pressure into two independent pseudo-linear subsystems of SISO according to the characteristics of the gas collector pressure system in coke oven, such as strong external disturbances, non-linear and coupling relations, etc. Meanwhile, an internal model controller was introduced into the two subsystems to guarantee their robustness and stability. Simulation and application results show that the control strategy has good decoupling features, and improve the rapidity, tracking accuracy and robustness of the system. And the gas collector pressure can be controlled in reach the desired technology range.

Abstract:During the process of oil-gas drilling, the problems of wellbore instability, such as the shrinkage and the sloughing of borehole, usually happen because of rock creep. We first analyzed the three stages of rock creep based on the law of the conservation of energy and explained the reason why the traditional rock creep model cannot well describe the accelerating stage of rock creep. Then, we modified the Nishihara model and relevant constitutive equations by increasing a winding device. Some experimental results of several kinds of rocks forming different formations were used to validate the modified Nishihara model. The verification results indicate that this model can describe the creep characteristic of rock effectively. Especially the accelerating creep stage of rock can be simulated very well when the stress exceeds the long-term strength. This modified Nishihara model provides a theoretical foundation for revealing the objective law of the rock creep.

Abstract:In order to analysis and improve the strength of G324 tractor frame, according to the actual condition of the tractor, we analyzed the bending and the torsional conditions which have great impact on the frame and established a finite element calculation model of the G324 tractor vehicle frame using the HyperMesh finite element analysis software. Through calculating the stress distribution of the frame in the two kinds of working conditions, we improved the frame and analyzed the stress distributions of adding L plate, changing the saddle tile wheel plate to plane plate and canceling reinforcing plate, respectively. At last, we figured out the specific model of the frame to meet strength requirements, and the results could provide references for the design and improvement of tractor frame.

Abstract:Taking rebound modulus value of cement stabilized weathered sand distributing around the Three Gorges reservoir as the research object, we made samples by mixing the weathered sand with 3%, 5%, 7%, and 9% cement respectively, then cured the samples for 7, 14, 21, 28, 35, 56, 70 d respectively, and carried out the resilient modulus test. The experimental results show that mixing cement can significantly improve the rebound modulus value of the weathered sand. Under the same curing age, with the increase of cement content, the rebound modulus value gradually increases and its growth magnitude first increases and then decreases. The relationship between the cement content and the rebound modulus value expresses good logarithmic function. Under the same cement content, with the increase of curing age, the rebound modulus value also gradually increases linearly. Within the first 28 days of curing, the growth of rebound modulus value is about 95% of that of the entire test period. Through regression analysis, the mathematical model between the cement content and the rebound modulus values and the mathematical model between the curing age and the rebound modulus values were established respectively. And the correctness and the accuracy of the mathematical models were further verified through additional test.

Abstract:Finite element models about bus rollover and passenger restraint system were created according to ECE R66 requirements. Simulation and experimental study on the rollover test for bus and the dynamic test for bus seats were performed. The good agreement between the simulation results and the experimental data proves the accuracy of the finite element models used in the rollover simulation study. 4 Hybrid III 50% dummies were placed at the structurally weakest body section of the bus. And the injury risk of dummies with three different passenger restraint systems (no seatbelt,two-point seatbelt and three-point seatbelt) was respectively evaluated during bus rollover. Simulation results illustrate that the dummies with no seatbelt protection suffer great risk of head and neck injury. Two and three point safety belts provide somewhat similar protection of neck and chest for all the dummies. Most of the dummy heads are well protected by two-point seatbelts except the one that is placed in the outboard seating position on the struck side of the bus.

Abstract:In order to study the effect of the stiffness of flexible bus on the seismic response of the ultra-high voltage (UHV) electrical equipment, the author established a computing formula with considering the bit-shaped function, the maximum sag and the maximum stress of the flexible bus. And the formula was verified by a comparative analysis between the test results and the finite element method (FEM) results. The finite element analysis results show that when the bending stiffness of the flexible bus increases, the sag ratio of the flexible bus reduces, the earthquake coupling function of the flexible bus between UHV equipments and the flexible bus enhances and the tensile effect of the flexible bus to the equipment is reinforced, and thus the seismic response of UHV equipment with flexible bus increases. The effect of the stiffness of the flexible bus on the seismic response of the equipment with high frequency is greater than that of the equipment with low frequency.

Abstract:The compton scattering of solution is a very meaningful aspect. On the basis of the Compton scattering of NaCl and KCl solution, we analyzed the relation expression between the Compton scattering photon number and the concentration of the solutions in theory by processing certain rational approximation, and then verified it through Compton scattering experiments. In order to grasp the micro-mechanism of Compton scattering of NaCl and KCl solution, we deeply analyzed the electronic structure of NaCl and KCl solutions according to the density functional theory. It is concluded that the factors influencing the Compton scattering photon number include electron number density, electron bound of scatterer, mass density, concentration of solutions and scattering attenuation coefficient, among which electron number density is the main factor.

Abstract:In order to research the influence of uncertain parameters on the static strength of planet carrier, we took the relief cut as the research object, and found out sensitive parameters from uncertain parameters using the standard deviation analysis method. D-OPT method was used to sample these parameters, the maximum principal stress was calculated by using fine FEM model, and then the polynomial response surface could be build based on these samples. Based on the fast response surface function, the Monte Carlo method and the statistical analysis were introduced to analyze the influence of sensitive parameters (interference, blend R1 and thickness tolerance) on the maximum principal stress, and the reliability of the static strength was evaluated. The results show that the discreteness of the interference and the thickness tolerance has obvious influence on the static strength. And the reliability of the planet carrier reaches 99.3%, which means the reliability is very high even if the reduction coefficients of GL and IEC are considered.