摘要：Percussive-rotary drilling technology was considered many years ago as one of the best approaches for hard rock drilling. It is a key for popularizing this technology on a large scale to design and make an impactor with excellent performance. This paper presents a suit of method to design the percussive parameters for the oil or gas field by introducing the working principle of back-pressurod impactor, dividing the working periods of impaetor into three phases and establishing the computer emuiational model of percussive parameters. It draws a comparison between the results of model calenlation and experiment on the basis of analyzing the experiment results of impactor. The conclude provides credible foundation for designing and further ameliorating the impactor.

摘要：Background:The nanotechnology boom and the ability to manufacture novel nanomaterials have led to increased production and use of engineered nanoparticles(ENPs).However,the increased use of various ENPs inevitably results in their release in or the contamination of the environment,which poses significant threats to human *** recent years,extraordinary economic and societal benefits of nanoproducts as well as their potential risks have been observed and widely *** estimate whether ENPs are safe from the onset of their manufacturing to their disposal,evaluation of the toxicological effects of ENPs on human exposure,especially on more sensitive and vulnerable sectors of the population(infants and children)is *** sources:Papers were obtained from PubMed,Web of Science,and Google *** search words included:"nanoparticles","infants","children","exposure","toxicity",and all relevant ***:A brief overview was conducted to 1)characterize potential exposure routes of ENPs for infants and children;2)describe the vulnerability and particular needs of infants and children about ENPs exposure;3)investigate the current knowledge about the potential health hazards of ENPs;and 4)provide suggestions for future research and regulations in ENP ***:As the manufacturing and use of ENPs become more widespread,directed and focused studies are necessary to measure actual exposure levels and to determine adverse health consequences in infants and children.

摘要：Going beyond the analytical model of the holistic state in rule of law discussion, we can classify the rule of law into national and local levels based on the stages and increments of its execution. The phenomenon of the local rule of law reflects the stages and incremental progress of building a rule of law China. It has a realistic foundation in society and a profound basis in legal theory. Comprehensively advancing the rule of law in China necessitates giving encouragement and support to construction of the rule of law at the local level. The attempts and experiments of local government enable us to explore and innovate the developmental model of the socialist rule of law with Chinese characteristics. The rule of law at the local level is embodied in three dimensions： ＂text--action---concept.＂ Assessment mechanisms and indicators for the local construction of the rule of law should also be established in accordance with this framework. The building of the rule of law at the local level should be synchronized with assessment of the rule of law. We need to optimize top-level design, conduct evaluations of local legislation, improve local rule of law work performance assessment and use a nile of law index to assess the local rule of law in an overall manner.

摘要：To overcome the bottleneck of the one-way translation from VR （ virtual reality） to CAD in VR-based CAD system, this paper proposes a Web-based VR-CAD system WVCD （ Web-based virtual conceptual designer） to support both customers＇and design team members＇involvement in the conceptual design and analysis activity over the Internet. It provides users with both parametric and freehand methods to create and edit 3D conceptual models with different levels of complexity in a VR environment intuitively without the need of switching between the VR environment and CAD tools. As a simple and low-cost VR-CAD system, WVCD can help to popularize and improve the Web-based collaborative conceptual design.

摘要：A 20 degree of the freedom model of the micro-suspended monorail is established to analyze a new type of the vehicle system named micro-suspended *** formula of the tire is established by using the magic *** the modal analysis of the vehicle,the modes of the vehicle are obtained,and resonance has little effect on the *** the vehicle moves in a right turn curve,it yaws in the clockwise *** the action of the guidewheel(stable wheel)force,the front bogie yaws clockwise but the rear one yaws ***,the two bogies and the car body roll during the curve passing process of the *** the vehicle speed is high enough,the left drive wheel will derail and the anti-overturning moments are provided by the stable ***,the car body yaws in the counterclockwise direction when it moves out of the *** the simulation of the vehicle passing the curve,the clearance between the guide wheel and rail surface will lead to a fatal impact on the *** the same time,the dynamic response of the vehicle under the crosswind is *** vehicle will not overturn due to the ***,the collision of adjacent vehicles is *** results show that there is an intermittent collision force between two vehicles due to the vehicle's non synchronous pitch motion.

摘要：To investigate the process optimizationof Cu-en/AP composite microspheres preparation via electrostatic spraying,and to reveal the effects of droplet properties and flow rate variations on the experimental results during the electrostatic spraying process,the prepared process parameters of Cu-en/AP composite microspheres by electrostatic spray method under the orthogonal experimental design simulated by ANSYS(Fluent).The influence of flow rate,solvent ratio,and solid mass on the experimental results is examined using a controlled variable *** results indicate that under the conditions of a flow rate of 2.67×10^(-3)kg/s an acetone-to-deionized water ratio of 1.5∶1.0,and a solid mass of 200 mg,the theoretical particle size of the composite microspheres can reach e *** trajectories in the electric field remain stable without significant *** simulation results show that particle diameter decreases with increasing flow rate,with the trend leveling off around a flow rate of 1×10^(-3)kg/*** the solvent ratio increases(with higher acetone content),particle diameter initially decreases,reaching a minimum around a ratio of 1.5∶1.0 before gradually *** the solid mass also reduces the particle diameter,with a linear increase in diameter observed at around 220 ***-en/AP composite microspheres with nanoscale dimensions were confirmed under these conditions by the final SEM images.

摘要：A central composite design(CCD),with three variables and three levels,was used to optimize withering and fermentation processing during manufacture of Congou black tea of *** three independent variables were withering time,fermentation time and fermentation *** factor was set by three *** responses were predicted by analysis of the regression *** the study,the models of regression equation were significant by the analysis of variance(ANOVA).The second-order response surface figures were showed that interaction term is correlated with the *** process parameters for the maximum of TF and TR formation were obtained at withering time of 12 hours,fermentation time of 2 hours,and fermentation temperature of 30℃.The predictions of TF and TR formation were 0.52% and 3.98%.The results obtained in this study showed that the CCD and Response Surface Methodology(RSM) could be an effective tool to optimize the process parameters of Congou black tea manufacture.

摘要：By introducing multi-agent technology to the online teaching system and establishing a personalized online teaching system model, the intelligent and personalized problems in the traditional online teaching system are solved; the needs of students for learning are fulfilled; the intelligent and interactive functions of the online teaching system are improved; a new interactive online teaching model is implemented. In this paper, the online system design based on multi-agent system technology is raised, and the modules and functions of the system are defined.

摘要：This paper presents the generalized reduced gradient method （GRG） and its realization forms. The application example of GRG in the optimization design of a single-stage cylindrical gear reducer is introduced. The algo- rithm of the GRG method is realized in Vissim software. Based on the mathematical model of the single-stage cylin- drical gear reducer, the simulation structure of the optimization design was achieved. The experiment results show that the GRG method has fewer iterations and higher precision. The GRG method is very suitable for solving mechanical optimization design.

摘要：In this paper, a miniaturized bionic electronic nose system is developed in order to solve the problems arising in oil and gas detection for large size and inflexible operation in downhole. The bionic electronic nose chamber is designed by mimicking human nasal turbinate structure, V-groove structure on shark skin surface and flow field distribution around skin surface. The sensitivity of the bionic electronic nose system is investigated through experimentation. Radial Basis Function （RBF） and Support Vector Machines （SVM） of 10-fold cross validation are used to compare the recognition performance of the bionic electronic nose system and common one. The results show that the sensitivity of the bionic electronic nose system with bionic composite chamber （chamber B） is significantly improved compared with that with common chamber （chamber A）. The recognition rate of chamber B is 4.27% higher than that of chamber A for the RBF algorithm, while for the SVM algorithm, the recognition rate of chamber B is 5.69% higher than that of chamber A. The three-dimensional simulation model of the chamber is built and verified by Computational Fluid Dynamics （CFD） simulation analysis. The number of vortices in chamber B is fewer than that in chamber A. The airflow velocity near the sensors inside chamber B is slower than that inside chamber A. The vortex intensity near the sensors in chamber B is 2.27 times as much as that in chamber A, which facilitates gas molecules to fully contact with the sensor surface and increases the intensity of sensor signal, and the contact strength and time between odorant molecules and sensor surface. Based on the theoretical investigation and test validation, it is believed that the proposed bionic electronic nose system with bionic composite chamber has potential for oil and gas detection in downhole.