Porcelain tooth is an ideal prosthesis of oral diseases. Limited by the fabrication process, there are always some internal defects in porcelain teeth, such as stomas, shrinkages and bubbles. These defects affect the service life and strength of porcelain teeth. It is proposed to scan the porcelain teeth by MicroCT. Then the defects can be displayed clearly through image processing. Subsequently, some features of defect are extracted, including areas and positions. Finally, the statistics of these features are analyzed in order to giveadviceto improve the fabrication process of porcelain teeth. The analysis results show that the distribution of area of internal defect obeys Weibull distribution, that is, the number of internal defects with large area is small but the number of internal defects with small areas is quite large. It reveals that most of defects are caused by porosity and shrinkage, which often result in small area defects. Additionally, the defects are mainly located at crown and joint surface, where the stress concentration is often located. Therefore, there are two methods to reduce the defects. One is reduce the stress concentration and the otherto improve the gas exit.

The theoretical study of the signal in certain sequences is helpful to analyze the factors that affect the imaging quality and improve the imaging quality in magnetic resonance imaging. Bloch equation is one of the most universal methods to solve the dynamics behavior of nucleus in magnetic field. Bloch equation and its solutions can be written in matrix form. By acting on magnetization (the Vector M), the propagator matrix that contains some parameters, such as main magnetic field, Radio Frequency pulse (RF), relaxation time, can be used to calculate signal of magnetic resonance imaging (MRI) in different circumstances of MRI sequences.

In order to solve the disadvantages of the current mechanical positioning, a high speed vision positioning and correction system for a thin silicon wafer is proposed. The visual location algorithm gets the "master yuan" using the chain code tracking and Principal Component Analysis (PCA), on the basis of the line detection algorithm of line segment clustering, the edge line of the cell is fitted, and then the cell position and angle deviation are calculated, and finally, position and angle are corrected by using manipulator. The experimental results verify the practicability of the algorithm. In the actual production, the system can quickly and accurately locate and correct the battery, greatly increasing the efficiency and accuracy of the battery string welding.

To solve the unbalanced bus passenger flow during weekday rush hours in China's big cities, a multiple linear regression model is established by collecting the bus IC card data, weather data and line data, considering the weather types, temperature and wind factors which influence the passenger flow. The results show that the model can forecast, quickly and precisely, the bus weekday passenger flow in each peak period, which may provide the basis for reasonably scheduling bus passenger flow.

When the Xgboost framework is in use, it is often involved in the adjustment of various parameters, and the selection of parameters has a great influence on the classification performance of the model. The traditional parameter optimization method usually first derives a penalty function, and then the empirical or exhaustive method is used to adjust the parameter value to maximize or minimize the penalty function, but often encounters a model without an explicit expression. The optimization of the parameters of this model is very troublesome, also bringing some uncertainty and randomness to the algorithm. The Bayesian optimization algorithm based on Gaussian method (GP) is used to optimize the parameters of the Xgboost framework. A new algorithm, GP_Xgboost, is proposed and experimented by multiple sets of numerical values. The results show that the proposed algorithm is superior to the manual tuning and exhaustive method, which proves the feasibility and effectiveness of the proposed algorithm.

Simultaneous wireless information and power transfer (SWIPT) is an effective way to prolong the operation time of energy-constrained wireless relay systems. A large-scale antenna array based SWIPT orthogonal frequency division multiplexing (OFDM) decode and forward (DF) relay system, in which the source is equipped with large-scale antenna array, is considered. The transmission process is divided into three time-slots. In the first time-slot, the source transmits power to the relay using maximum ratio transmission beamforming; in the second time-slot, the source transmits information to the relay; in the third time-slots, the relay transmits the information to the destination using the harvested energy in the first time-slot. Both the power allocation (PA) over the sub-carriers for information and power transmissions from the source to the relay and from the relay to the destination, and the time allocation (TA) between the first, second and third time-slots are investigated. An optimal joint PA and TA algorithm has been proposed. Computer simulation results shows that the proposed algorithm outperforms some benchmark schemes.

A study is conducted on the reactive power optimization in distribution network of the wind farm. The reactive power characteristics of the double-fed wind turbine are analyzed, and the wind farm is used as a continuous reactive power adjustment means to participate in the reactive power optimization of the power system. A multi-objective reactive power optimization method is proposed based on fuzzy quotient and chaotic sequence dynamic particle swarm optimization algorithm. The fuzzy entropy weight method is used to solve the defects of subjective weight and objective weight, and a multi-objective reactive power optimization decision model with wind power is proposed based on static voltage stability margin, voltage deviation and active power loss. In order to solve the local convergence with traditional particle swarm algorithm, combined with Chebyshev mapping and Logistic mapping, a combinatorial chaotic mapping is used to enhance the homogeneity of the initial particles in the particle initialization, and Logistic chaos optimization is introduced to the process of algorithm optimization, strengthening the global optimization ability of the algorithm. The IEEE14-node system is used as a test case, and the result proves the feasibility and validity of the proposed method.

The problem of two-person Nash differential games for delayed nonlinear stochastic systems with state- and control-dependent noise is discussed. A sufficient condition for the existence of the Nash equilibrium strategy is presented in terms of coupled Hamilton-Jacobi equations (HJEs). And meanwhile, the explicit expression of the equilibrium strategy is given. In the end, a numeric example is employed to show the effectiveness of the obtained results.

The dynamics of the first order delay differential equation is studied by applying an Euler method. It is showed that a sequence of Hopf bifurcations occur at the positive fixed point as the delay increases. Meanwhile, the stability of the fixed point is analyzed. At last, some numerical experiments are given to verify the correctness of the result.

A Beidou/GPS navigation receiver based on Xenomai RTOS in Linux operating system is designed. The main part of this receiver consists of SoCFPGA. The Xenomai real-time Linux system using HPS in the main part is responsible for system initialization, task scheduling, RF front-end driver, loop capturing and tracking control, bit synchronization and frame synchronization and positioning calculation, and the FPGA is used to collect data, capture and track satellite signal. After a series of tests, the task response delay of the real-time Linux system based on Xenomai is less than 15 microseconds, which can meet the real-time requirement of Beidou/GPS navigation receiver, and the test value of CEP of this receiver reaches 2.290 4 meters, which can also meet positioning requirement. In addition, the receiver can support output differential positioning of raw data and extended integrated navigation.

Based on the physical model of the exhaust turbocharger control mechanism, the mathematical model for the turbine mechanism and the control mechanism is established by the energy balance equation and the force balance equation, which determines the relationship between the boost pressure and the duty cycle of the control solenoid valve. Using PID (proportion-integral-derivative) control mode to control the output duty cycle to make sure the actual boost pressure follows the target boost pressure. The vehicle road test results show that the boost control effect is good. Compared with the pre-pulse control system, the pressure deviation value changes more smoothly. The control system is feasible.

The direct contact liquid desiccant air conditioning driven by heat pump with freon as working fluid has the problem of air carrying desiccant solution, and this kind of working fluid is likely to destroy the environment. So an integrated system of membrane liquid desiccant air conditioner and carbon dioxide transcritical cycle heat pump system is presented, and the theoretical model of the system is established. The application of this system in a hotel in Guangzhou and the simulation analysis show that the integrated system performance coefficient EER is 8.8 and 0.65 for dehumidification efficiency. In full load condition, the design and performance difference of the "integrated system and dry air filter system of dry fan coil" and the "traditional fan coil and fresh air conditioning system" are compared and analyzed. The total power of the main equipment of the "integrated system and dry air filter system of dry fan coil" and the "traditional fan coil and fresh air conditioning system" are 74.3 kW and 90.5 kW, respectively. The air conditioning system based on the concept of THIC is 21.3% lower than the traditional fan coil plus fresh air conditioning system of electric power.

To study the effect of complex iron form and concentration on the growth of algae, EDTA-Fe, ferric humate, iron oxalate and ferric citrate were chosen to conduct a series of AGP experiments, which took Scenedesmus quadricanda and Anabaenaaquae as representative species of cyanobacteria and chlorophyta. The results show that both iron form and concentration have significant effect on the growth of Scenedesmus quadricanda. Besides, the latter (P≤0.01) is more effective than the former (P≤0.05). Anabaena flosaquae has a strong adaptability to the iron form and concentration. But high iron concentration still has an inhibitory effect on algal growth. The iron concentration has a very significant effect on the growth of Anabaena flosaquae (P≤0.01), while the iron form has no significant effect on them. Consequently, the iron concentration has a greater impact than the iron form on the growth of Anabaena flosaquae.

The 4-(1-adamantyl) styrene was synthesized by the hydroformylation reaction and Wittig reaction with 1-(4-bromophenyl) adamantane as raw material. And then the copolymer p(NVK-co-AdSt) with different content of adamantane were prepared by copolymerization of 4-(1-adamantyl) styrene and vinyl carbazole. The structures of the products and copolymers were characterized by FTIR, ¹HNMR and elemental analysis. The effects of adamantane content on the molecular weight and optical properties of the copolymers were investigated by gel chromatography and fluorescence spectroscopy. The results showed that the introduction of adamantane groups, the color purity and luminous efficiency of the copolymers were improved.

LiBH₄-NdCl₃ hydrogen storage system was prepared through high energy ball milling. The mechanism of NdCl₃ on LiBH₄ and the effects of pre-milling, milling time, ball-to-powder ratio, doping amount were systematically investigated. The results reveal that NdCl₃ reacts with LiBH₄ through destabilization effect showing a superior dehydrogenation performance. Reducing the NdCl₃ particle into nanosize which possesses higher surface energy can effectively modify the dehydrogenation of LiBH₄. The best balling time and ball-to-powder ratio are related to the original state of NdCl₃ with respect to particle size, crystal size and surface situation. Enhancing the contact area between LiBH₄ and NdCl₃ via increasing doping amount of NdCl₃ is one of the effective ways to improve the dehydrogenation performance of LiBH₄.

Hg, As and Cd in soil/sediment samples were determined with the refluxing digestion of aqua regia. Cd was determined by Graphite Furnace Atomic Absorption Spectrometry. Hg and As were determined by Atomic Fluorescence Spectrometry. 8 geochemical standard reference material of soil/sediment were tested. The test data showed that the determination of standard reference material were within the reference range. The relative standard deviation of Hg, As and Cd were 2.9%~8.2%,1.2%~5.6% and 3.4%~6.8%. The detection limit, precision and accuracy of the methods met the requirements of the determination of soil.

Land use and regional ecological security pattern is closely related. The panel data of China from 2004 to 2014 are selected on the national scale for this study. The CO₂ emission is integrated into the evaluation index system of land use and ecological security. The entropy method, the comprehensive evaluation function and the coupling and coordination model are used to estimate the land use and ecological security. And the coordination and coordination degree of land use and ecological security in 31 provinces and municipalities were analyzed with the help of ArcGIS software. The results showed that the land use comprehensive evaluation index, ecological security comprehensive evaluation index and coupling coordination index of 31 provinces and cities increased as a whole in 2004-2014, which indicated that in recent years, with the improvement of land use, the ecological security level had a positive trend development; that in the spatial differentiation of coupling degree of land use and ecological security, the coupling degree of the western region mainly lies in the low-level coupling stage and the antagonistic stage, the middle area is in the running-in stage and the high-level coupling stage is the eastern coastal area, and the coupling level of land use and ecological security is gradient spatial distribution. The cross-sectional data from 2004, 2009 and 2014 show that in recent years, the coordination degree of land use and ecological security in most of China's provinces and municipalities is a land-use type with moderate coordination and coupling, there is no extreme coordination between the provinces and municipalities in the coupling interval, indicating that the provinces and municipalities of China's land use and ecological security of the coordinated development level is still low. The study of the coordinated development of regional land use and ecological security is conducive to promoting the rational and efficient use of land in the region and solving the ecological and environmental problems.