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Fly ash is the most common solid waste in the industry, and its high value-added utilization has become a hot issue of study. Carrying out the green synthesis route of zeolite as the raw material of fly ash has become an extremely important scientific significance and practical value. In this paper, the research progress of fly ash-based zeolite was introduced from three aspects, including fly ash activation method, fly ash-based zeolite synthesis method and fly ash-based zeolite in the wastewater treatment sector. The relevant applications of fly ash-based zeolite as an adsorbent material in the treatment of wastewater pollution were summarized, and the development trend has prospected.

Ceramic particle reinforced iron-based alloys have been widely used in aerospace, land transportation and other aspects, so it has attracted tremendous attention. Aiming at the preparation and interfacial reaction of ceramic particle reinforced iron-based alloys, the preparation methods for interfacial reactions, reinforcement selection and design of ceramic particle reinforced iron-based alloys are introduced in this paper. Combined with the recent studies on ceramic particle reinforced iron-based alloys, this paper focuses on the ceramic particle reinforced iron-based interface and strengthening models/mechanisms, based on existing research, prospects for further ceramic particle reinforced iron-based alloys were studied.

Cerium oxide (CeO2) is one of potential candidates of hydrophobic coatings servicing in harsh environments. In this letter, abraded CeO2 surface was prepared using sandblasting treatment to investigate the wetting mechanism under the condition of impact abrasive wear. The water contact angle (WCA) of the abraded surface increased from 62.8° to 93.7° after aging in ambient air for about 700 h. The hydrophobic self-optimisation mechanism of the abraded CeO2 surface is due to the hierarchical structure formed during impact abrasive wear and the surface adsorption of airborne hydrocarbon, resulting the wetting state changed from “Wenzel state” to “Cassie-Baxter State”.

Grain characteristics of rolled 1235 aluminum alloy were studied by EBSD. The effects of hot rolling, cold rolling and rolling deformation on grain boundaries and grain size of the metal were studied as well. The content of high-angle boundaries was low by 16.48 % in 50 % hot-rolled 1235 aluminum alloy. The complete dynamic recrystallization occurred, and grains were coarse. During 90 % hot rolling, the low-angle boundaries turned into high-angle boundaries constantly. The content of high-angle boundaries was higher by 40.16 %. Coarse grains broke into fine grains, and grew into medium grains. In the 90 % cold-rolled alloy, the trace shape of high-angle boundary was irregular. The lattice distortion was large, providing the energy needed in recrystallization during recrystallization annealing.

La0.8Sr0.2MnO3 was prepared to investigate the infrared emissivity of the sample under 0.76-2.5 μm and 2.5-500 μm infrared fields. The sample exhibited characteristic peaks of rhombohedral perovskite structure at 298-318 K, and split of the main peak weakened with increasing temperature. Intensity of the ferromagnetic resonance peak enhanced with increasing temperature, and the peak was shifted toward high magnetic field. A weak paramagnetic resonance peak appeared at 318 K, indicating that ferromagnetic-paramagnetic transition was occurring. The temperature of the sample under 2.5-500 μm field was higher than that under 0.76-2.5 μm. The emissivity of the sample increased with radiation time under 2.5-500 μm, but it had no obvious changes at about 0.665 under 0.76-2.5 μm. The emissivities at the same temperature fields were higher than those under 0.76-2.5 μm and 2.5-500 μm fields, respectively. It suggested that 0.76-2.5 μm and 2.5-500 μm radiations had inhibition effect on emissivity of La0.8Sr0.2MnO3.

Molecular dynamics simulation was used to investigate two models of aqueous solution ofcalcium carbonate system between 283K and 373K. The diffusion coefficients of water moleculesdemonstrated that both the electropositive surface (110) on Model-I and neutral surface (104) onModel-II showed interaction with the water molecules, and the surface (110) exhibited strongerelectrostatic interaction with water molecules than the latter, besides obvious anomaly appeared near343K on Model-I. On the other hand, surface (110) exhibited anomalous influences on Ca2+ andCO32- ions near 313K and 343K on Model-I, and only a broad anomaly on CO32- ions near 343K onModel-II. The binding energies between surface (110) / (104) and Ca2+ /CO32- ions demonstrated thatthe surface (104)were more favorable for the growth of the new crystal but weak for the diffusion.

Copper-Nickel alloy pipes in marine engineering have been suffering severe seawater corrosion and erosion-corrosion. In this work, six kinds of Cu-Ni alloy pipes with different service lives delivered by two manufacturers were used to clarify the relationship between corrosion resistance and microstructure. The corrosion behaviors of the samples in 3.5 wt.% NaCl solution were studied by electrochemical measurements. Chemical composition, grain size distribution, crystallographic orientation, and grain boundary characterization distribution (GBCD) were investigated by energy-dispersive spectrometry (EDS), metallography and electron backscattered diffraction (EBSD) technology. There were no obvious differences in chemical composition and GBCD in contrast with size and uniformity of grains. Pipes with large grains and a broader grain size distribution had better corrosion resistance. It was also found that the accuracy of experimental data greatly depended on the quality of the sample surface in EBSD analysis. The scratches and contamination during sample preparation have a strong impact on the imaging quality and the calculation of GBCD.

Nanofluids is an innovative study of nanotechnology applied to the traditional field of thermal engineering. It refers to the metal or non-metallic nanopowder was dispersed into water, alcohol, oil and other traditional heat transfer medium, to prepared as a new heat transfer medium with high thermal conductivity. The role of nanofluids in strengthening heat transfer has been confirmed by a large number of experimental studies. Its heat transfer mechanism is mainly divided into two aspects. On the one hand, the addition of nanoparticles enhances the thermal conductivity. On the other hand, due to the interaction between the nanoparticles and base fluid causing the changes in the flow characteristics, which is also the main factor affecting the heat transfer of nanofluids. Therefore, a intensive study on the flow characteristics of nanofluids will make the study of heat transfer more meaningful. In this experiment, the flow characteristics of SiO2-water nanofluids in two-dimensional backward step flow are quantitatively studied by PIV. The results show that under the same Reynolds number, the turbulence of nanofluids is larger than that of pure water. With the increase of nanofluids volume fraction, the flow characteristics are constantly changing. The quantitative analysis proved that the nanofluids disturbance was enhanced compared with the base liquid, which resulting in the heat transfer enhancement.

The regenerative braking strategy for precursor pure electric vehicle was studied in this paper. Firstly, a constraint optimization model was established for the braking force distribution, in which both braking stability and recovery efficiency of braking energy were taken into account. Secondly, Particle Swarm Optimization (PSO) algorithm was applied to optimize the multi key parameters in the model. Finally, the optimized braking torque of the motor was obtained at different speed, different braking strength and different battery charge state. A vehicle model was built to validate the optimized results through simulation. The results showed that, compared with the original control strategy, the optimized control strategy not only could increase the braking stability effectively, but also improve the energy recovery efficiency in a certain extent.

The self-mixing interference (SMI) effect with multiway feedback is analyzed in this paper. The basic theory of SMI with multiway feedback external cavity (MFEC) can be derived from the theory of interference as well as the theory of laser self-mixing interference (LSMI). Based on the external cavity structure with MFEC, a SMI model with two feedback external cavity structure is proposed. The expressions of the phase and output power in the MFEC are deduced and some simulation analyses are made. It is found that the output signal of the SMI system with two external cavity is sinusoidal or sawtooth waves, which is similar to the signal of SMI with a low frequency sinusoidal phase modulation. The density of interference signal fringes is uneven in one period and the shape of the interference wave is determined by the intensity of the external feedback. Furthermore, a SMI with two feedback external cavity experiment system is considered, and the experiment verifies the simulations.

An entirely novel preparation method of calcium carbonate (CaCO3) from calcium hydrogen carbonate (Ca (HCO3)2) solution was presented and named as thermal decomposition. The variation of the polymorphs and morphologies of CaCO3 particles with reaction temperature was investigated. XRD result indicates that high temperature favors the formation of calcite. Cubic or rhombohedra calcite crystals, lamellar and spherical vaterite crystals and rod– and needle–like aragonite crystals are found in powder synthesized at different temperatures. The reaction process was also discussed in the present work.

According to the characteristics of firebricks palletization and the structure of the manipulator, this paper puts forward the concept of using group policy to palletize firebricks by robot. On this basis, the concept of “Horizontal bar “and” Horizontal slice " is introduced with features of stacking firebricks. Then mathematical model is constructed to palletize Firebricks in shortest time. The firebrick robot palletising optimization model has been applied in the enterprise.

In this study, influences of mixing procedure on the latex adsorption behavior, slurry fluidity and setting time of latex modified cement paste (LMCP) mixed with polycarboxylate (PC) as superplasticizer were analyzed. There were three kinds of mixing procedure: LMCP added latex later than PC (LMCP-L), LMCP added latex before PC (LMCP-B), LMCP added latex and PC simultaneously (LMCP-S). The results show that, the adsorption isotherm of SAE latex by cement grains fits the Langmiur type, and the presence of PC can affect the adsorption behavior. Regardless of the mlatex/mcement (4% or10%), LMCP-B had the highest amount of adsorbed latex and slurry fluidity while LMCP-L had the lowest. And, the LMCP-B also had the longest initial and final setting times, while the setting times of LMCP-L and LMCP-S were comparable.

In this study,influences of latex and mixing procedure on flexural strength, compressive strength, elastic modulus and apparent fracture energy of hardened cement paste mixed with polycarboxylate (PC) as superplasticizer were analyzed. The results show that, the apparent density of fresh latex modified cement paste (LMCP) and the compressive strength of the hardened LMCP were reduced 1%-8% and 0-28% respectively compared with the control, while the flexural strength and apparent fracture energy were increased 11%-70% and 22%-157% respectively. In generally, the mixing procedure had gentle effect on the mechanical properties of harden LMCP with the same mp/mc, while the different mp/mc and latex types had greater impact. The amounts of polymer adsorbed changed by mixing procedure and had significantly effect on the properties fresh LMCP while very little on the harden LMCP.

Joining between polyamides (PA) and metals has potential applications in the industry. Based on PA66GF and AISI304, the experimental study of laser transmission joining of the dissimilar materials is conducted in this article. Firstly, comprehensive experiments of laser transmission joining between PA66GF and AISI304 are carried out by Nd: YAG pulsed laser source according to the central composite rotatable design method (CCRD). Secondly, the effects of the process parameters like voltage, joining speed and stand-off distance on the joint quality are analyzed by response surface methodology (RSM). Finally, mathematical models between the process parameters and the lap-shear strength and the joint width are established and based on which, the optimization of the joining process is done and the optimized results are predicted. The results show that the process parameters of laser transmission joining play a significant role in determining the joint quality; the predicted data of the models are in good agreement with the experimental results and can be of great help for the optimization of the joining process. As a result, this study could provide an effective instruction about how to choose the reasonable process parameters for enhancing the joining efficiency.

To improve the preparation technology and mechanical properties of carbon/carbon composites, a kind of Zirconium dioxide modified Carbon/carbon (C/C–ZrO2) composites were prepared by Sol-Gel Process combined with isothermal chemical vapor infiltration (ICVI) method. This method could shorten preparation cycle greatly to reduce the cost. The microstructures and mechanical properties of the C/C–ZrO2 composites were investigated. The results indicate that the ZrO2 modified phase is uniformly distributed in the carbon matrix, the bending strength and modulus of C/C–ZrO2 composites are much higher than unmodified C/C composites due to its particle toughening and fiber toughening.

The factors that influence environmentally-friendly powder rubber powdering are introduced. Types and dosage of isolation agent, types and dosage of coagulant, environmental antioxidant, condensation temperature, stirring speed on the effect of powder rubber are examined. Thus a simple method to prepare environmental powder rubber is provided.As a physical variation of traditional bulk rubber, powder rubber can change the situations that high energy consumption and high labor intensity of the former. And it also can make the mixing process become continuous, automated, energy-saving and so on. In recent years, with the progress of rubber processing industry, the demand of powder rubber increases rapidly. And there is a intense requirement of supplying environmentally-friendly powder rubber[1-3]. So it is very important to do this experiment.

Taking Pingzhai Village in Sanming City of Fujian Provice as the researching area, the village has already outbroken Children’s blood lead exceeding and cause a lot of damage to local children. In order to reveal the reason for this serious consequence and assess the environmental risk of Pb, 24 soil samples including 12 from parent material layer and 12 from the corresponding surface layer and 4 groundwater samples are collected. The Tessier sequential extraction method is applied to analyze different speciation of Pb in soil, and Risk Assessment Code (RAC) and Ratio of Secondary Phase and Primary Phase (RSP) are both applied to evaluate Pb contamination degree and ecological risks. The results show that: the concentration of Pb in soil samples exceeds the soil Pb background values of Fujian Province, and the overall concentration of Pb shows a rising trend from the surface to parent material layer, then their accumulated pollution index range from 5.4 to 54.9 in surface layer and 4.7 to 68.1 in parent material layer. Coefficients of variation of Pb in surface and parent material layer are 79% and 86%, respectively. The lead in soil can be divided into 3 chemical speciation containing T1 (exchangeable speciation and carbonate bounded form), T2 (potential ecological risk form) and T3 (residual speciation) and Pb in soil mainly exists in T2 and T3. There shows a significant positive correlation between T2 or T3 and the total amount of Pb in soil. Pb concentration in groundwater has exceeded limited value of Standards for Drinking Water Quality. RAC and RSP ecological risk assessment results indicate that: environmental risk level of RSP is higher than it of RAC, and the contamination degree and potential environmental risk level of parent material soil are higher than them of surface soil applied by the two assessment methods.

According to the characteristics of high altitude and strong ultraviolet radiation in Tibet, this paper do ultraviolet irradiation experiment research to different strength grades of concrete blocks in a closed laboratory, it is found that ultraviolet rays has promoting effect to early strength growth of test block, but the growth became slow along with the time.

Combined with the characteristics of forest image, the paper puts forward a new forest fire image segmentation method based on YCBCR and local fractal dimension. First of all, convert the image in RGB color space into YCBCR. Secondly, original triangle prism model algorithm which calculates the square of block matrix is replaced with four pyramid model. This algorithm is easy to be realized, reduce the amount of calculation model, and speed up the image segmentation speed. Segmentation effect significantly is improved, and the simulation experimental results show that this algorithm can be very good for the segmentation image of the flame extracted from complex background. It has obvious, accurate and fast effect and provides a good foundation for the future image analysis and recognition processing.

Microstructure and mechanical properties of automobile beam used BS700MC low carbon micro-alloy steel welding joint were investigated by cold crack sensitivity, microhardness test, bending, impact, tensile and metallographic analysis. The results showed that the BS700MC steel has better crack resistance, and without heat treatment before welding with the WH80-G welding wires. The microstructure of joint’s weld seam is acicular ferrite, very little bainite and proeutectoid ferrite. The hardness value of weld seam zone is 380 HV and is the same as that of base metal. But the lower of weld joints rigidity has obvious fluctuations, and the HAZ appears softened phenomenon. The welding joint has good impact toughness only between 20 and minus 20 degrees Celsius.The tensile strength of BS700MC welded joint reaches 815 MPa, 97.1% of base metal, fracture position in HAZ. Tensile fracture morphology is mixed type indicating dimple and cleavage steps, and welding joint have good comprehensive mechanical properties.

Risk assessment of debris flow is the core content and decision-making basis for debris flow disaster forecasting and the disaster prevention work. It is a comprehensive analysis for the geological, climate, rainfall, historical disaster activities and human engineering activities in some certain areas which may be in danger conditions, so as to determine the occurrence probability of debris flow. In this study, risk assessment model of the debris flow gully in Tibet southeast area is established. According to the correlation ratio of risk assessment indexes and the debris flow occurrence, the assessment indexes can be divided into three levels and defined with some certain values according to the correlation of debris flow occurrence. Finally, the risk assessment of debris flow gully in Tibet southeast area is conducted, and model outputs achieve a good result.

The mechanism of cable crosstalk involving what and how does the factors affect the level of crosstalk is introduced in detail. A transmission line model for predicting crosstalk between power cable and the other wires nearby with common reference ground based on multiconductor transmission theory (MTL) is developed. Crosstalk among circuit configurations when the victim cables with load terminations are different types is analyzed and simulated. Models where the types of the victim lines are shielded coaxial cable, shielded twisted pair and unshielded twisted pair are simulated. It is found that the shielding can provide an attenuation of about 50dB than the unshielded cables. In addition, the condition of multi-cable coupling is simulated and some thoughts are brought out to inspire more detailed study. Finally, some measures are suggested to suppress the crosstalk between cables according to the two-type of coupling mechanism (inductive coupling and capacitive coupling).

This paper systematically presents a thorough analysis on the construction of the heating monitoring system in Nanjing General Hospital, China. The monitoring method and strategy of were discussed in detail. Besides, the optimization design of the simple closed loop control system was conducted. Finally, an optimal operation analysis system consisting of the heating host machine, costumer thermal monitoring system, and outside environment monitoring system for the heating room was established. As a result, the heating quality, the heating efficiency, and the relationship with costumer were greatly improved.

Adsorption of Ni (II) onto modified attapulgite was investigated with respect to temperature, initial concentration and contact time. The kinetics data related to the adsorption of nickel from aqueous solutions were in good agreement with the pseudo-second order equation in ranges of initial concentration of 20-200 mg/L, and temperature of 298-328K.The thermodynamic experiment results showed that the equilibrium adsorption isotherm was closely fitted with the Langmuir model. Enthalpy change (△H0), entropy change (△S0) and Gibbs free energy change (△G0) were calculated from the temperature dependent sorption data, and the results indicated that the sorption of Ni (II) on modified attapulgite was a spontaneous process, and the sorption was endothermic.

Adsorption of Cu(Ⅱ) onto natural attapulgite was investigated with respect to temperature, initial concentration and contact time. The adsorption process can be well described by the pseudo-second-order kinetic model, and the equilibrium adsorption isotherm was closely fitted with the Freundlich model. Enthalpy change(△H0), entropy change(△S0) and Gibbs free energy change(△G0) were calculated from the temperature dependent sorption data, and the results indicated that the sorption of Cu(Ⅱ) on attapulgite was a spontaneous process, and the sorption was endothermic.

With the rapid development of China's economy and society, the power supply quality and reliability have become increasingly demanding for power user. Distribution automation becomes a power system to be implemented one of the goals based on the gradual promotion of information technology in promoting economic construction. This paper studies the distribution network communication method to determine the communication system hierarchy. Distribution communications network will cover the entire distribution automation master, terminals and related services, enabling the communication network can effectively meet the distribution automation system needs.

Power system visualization technology is essential in improving the power system automation and human-computer interaction environment. The power of information visualization technology can display a lot of information in a computer-generated image, and help system personnel to process and analysis of numerous grid data more efficiently. It provides a more intuitive operating platform for system operators.

With the sub-module number and scale growing on, the whole control system of MMC (Modular Multilevel Converter) tends to be much more complicated because of the cascade structure, which also intensifies the pressure of the converter main controller. To distribute the converter main controller’s task, the design of sub-module tenders itself extremely important. However, there is no explicit and comprehensive study on how to design the sub-module. This study, according to the characters of MMC, introduces a feasible architecture of hardware and software for the sub-module with optical communication. Each sub-module has its own independent controller and control system. That is to say, every sub-module is a complete system, which can do calculation and communication with outside. Sub-modules connect with the main controller of converter through communication using optical fibers. By adopting the optical communication, sub-modules not only can receive the control references data from the main controller, but also can send its own condition information back, which creates an interactive communication between the two sides. Additionally, through detailed experiments, the validity and feasibility of the design are demonstrated under two different control strategies.

Aiming at our country existing components database has some shortages, such as the data is not complete, scope of shortcoming, we develop a parts optimization library on the network based on the data of large number of parts. Firstly, expounds the overall structure of the database and research on system information technology. And then elaborate the main function modules of the system. Lastly, test the validity and practicability of the system combined with a specific example. After verification, the system can be very good to meet the needs of the enterprise to the type of resource demand.

With the development of computer and embedded technology, ubiquitous computing age is coming. In the ubiquitous age, people could get all kinds of services anywhere and at any time. In this paper, we design an indoor location system based on ultrasonic sensor and radio frequency technology. The ultrasonic positioning technology has many merits of high positioning accuracy, simple circuit structure and low cost. There are some components such as locating system, communication system, location system, security system and so on, emphasized supporting technologies in order to provide researchers with general cognition. The principle and the design of the system are described in detail. The system consists of the single chip circuit, the circuit of ultrasonic, the circuit of radio frequency signal, communication interface circuit and so on. Perceptual system can promote environmental intelligence and human services development, but also can promote public places security monitoring and early warning intelligence and automation.

The theoretical analysis of frost formation had been made. The wind speed, temperature and relative humidity etc. had different effects respectively. A single heating was studied through the experiment. In different outdoor conditions, experimental data showed evaporator frost at the environment temperature of 10 °C, environment relative humidity was 70%. Comparing the experimental data, it is concluded that temperature of evaporator’s outlet is increasing with the outlet temperature. The refrigerant evaporation temperature and COP under different conditions has been tested. The relation of evaporation pressure and environmental temperature under different evaporation temperature had been concluded. According to the experiment, a defrost measure of this experiment equipment had been proposed.

This paper presents a topic ontology tree based hierarchical HMM (hHMM), and the generation of topic property based life cycle curve is studied. Compared with the traditional methods, this model can describe the hierarchy relations of topics.

Certificateless-based signature can eliminate the need of certificates in the Public Key Infrastructure and solve the inherent key escrow problem in the identity-based cryptography. In 2012 Zhang et al. [J. Zhang and J. Mao, An efficient RSA-based certificateless signature scheme, Journal of Systems and Software, vol. 85, pp. 638-642, 2012] proposed the first certificateless signature scheme based on RSA operations and showed that their scheme is provably secure in the random oracle model. However, He et al. [D. He, M.Khan, and S. Wu, On the security of a RSA-based certificateless signature scheme, International Journal of Network Security, vol.16, no.1, pp.78-80, 2014] recently showed that Zhang et al.'s scheme is insecure against a type I adversary who can replace users' public keys. In this paper, we propose an improved version based on RSA which not only keeps the original security properties of the signature, but also is secure against a type I adversary.

The topic tree-based topic structure model is proposed using five-tuple and probability theory of ontology. Vocabularies in the glossary are presented with leaf nodes of the topic tree. The results of simulation experiment on real news corpus eventually show that the topic similarity of sym-KL divergence could construct a topic tree more accurately and dig the potential semantic topic characteristics of time and space more deeply in the text stream compared with other flat topic structure models.

Wireless sensor and actor networks (WSANs) additionally employ actor nodes within the wireless sensor network (WSN) which can process the sensed data and perform certain actions based on this collected data. In most applications, inter-actor coordination is required to provide the best response. One actor failure may lead to partitioning the inter-actor networks, tolerating the actor failure and restoring the lost connectivity need to be performed while imposing the least overhead on the individual actors autonomously. In this paper, we present a Self-healing Connectivity Recovery Algorithm (SCRA) which is to recover the failure actor. SCRA proactively identifies actors whether is a cut vertex or not to the network connectivity based on the depth-first search algorithm (DFS), and designates a minimal CDS backup nodes. If an actor node suddenly fails, the minimal block backup nodes move and initiate a recovery process until the network is reconnected. Through simulated experiments, the results show that the algorithm is more effective than present algorithms in terms of total travel distance, and total number of messages.

The voltage is the critical electrochemical parameter in microbial fuel cells (MFCs).There are three major oilfield wastewaters including water flooding produced water, polymer flooding produced water and ASP flooding produced water. These three wastewaters were used as anode substrate of three MFCs in this study. The influence and the influencing factors of the output voltage of the three MFCs and the produced water main refractory organics removal effect were studied. The results show that During this reaction period, MFCs cathode potential stays relative stable, however, anode potential shows a remarkable increasing trend, thus, the anode contributes mostly to the change in output voltage. COD removal effect of Anode substrate and the coulombic efficiency are both influencing factors of the anode potential .The microbial fuel cell for wastewater of surfactant, remove the best effect;For different produced water, oil and polymer removal effect abide by the MFC output voltage and COD value changing law.

By examining the compressive and flexural strength of composite and using scanning electron microscopy (SEM), we analyzed the influence of sodium hydroxide on the properties of FGD gypsum and slag composite materials and discussed the influence of sodium hydroxide on the setting time and mechanical strength of the composite materials and presented the action mechanism of sodium hydroxide as a stimulator. The results show that when the content of sodium hydroxide was percent of 0.25, the maximal strength of FGD gypsum-slag composite materials was reached.

This paper studies the seepage flow mathematical model of three-area composite reservoir under three kinds of outer boundary conditions (infinite boundary, constant pressure boundary and closed boundary), in which influences of well-bore storage and skin factor are not taken into consideration. On the basic of theory of similar structure of solution of boundary value problem of differential equation, this paper obtain the solution of the seepage flow model of three-area composite reservoir. The study is not only conducive to further analyze the inherent law of the solution and solve corresponding application problems, but also easy to compile corresponding analysis software.

In this paper, voltage fluctuation and stability analysis of critical buses was performed using multiple indexes to power system with wind farm connected. Considering the intermittency and randomness of wind speed, this paper constructed three voltage fluctuation indexes according to the characteristic of voltage random distribution. Bus voltage stability index was also calculated with the help of PV and QV curves in the paper. The simulation analysis performed in the DIgSILENT/PowerFactory basing on three machines nine nodes system with double-fed wind farm was carried out to reveal the impacts of wind generation uncertainty on voltage fluctuation and stability.

The virtual simulation experiment framework consists of hardware and software function modules, which are both designed in this thesis. The application of virtual experiment framework has changed the traditional teaching method to a large extent, reduced the cost of laboratory construction and management, which is of the first importance to realize the remote experiment teaching. Through virtual experiments, students' interest in knowledge is cultivated and innovation ability is enhanced. With the National Instruments Educational Laboratory Virtual Instrumentation Suite (NI ELVIS) and LabVIEW, we could take advantage of graphical programming and a complete suite of standard test instruments on computer and directly interface these instruments to circuits, which is the base of virtual experiment framework.

In view of solar arrays applied in large-scale stratospheric airship, modular thinking was proposed by reasonable decomposition of solar array to design composite maximum power point tracking (MPPT) controller where the input and output are both in parallel, which ensures maximized solar energy output on a limited area. And each solar array sub-model was equipped with independent MPPT controller to control power tracking separately. Then, the solar array composed of three sub-models was used for simulation and its result indicates that MPPT controller of each sub-model can track the power quickly, and the output power can reach 93% of maximum input power when the efficiency loss of converter in reality is not considered . So, the model constructed in this paper can be used to optimize the design and analyze output characteristics quantitatively for the large-scale stratospheric airship's solar array.

This paper presents a percolation model for the composite reservoir, in which quadratic-gradient effect, well-bore storage, effective radius and three types of outer boundary conditions: constant pressure boundary, closed boundary and infinity boundary are considered. With Laplace transformation, the percolation model was linearized by the substitution of variables and obtained a boundary value problem of the composite modified zero-order Bessel equation. Using the Similar Constructive Method this method, we can gain the distributions of dimensionless reservoir pressure for the composite reservoirs in Laplace space. The similar structures of the solutions are convenient for analyzing the influence of reservoir parameters on pressure and providing significant convenience to the programming of well-test analysis software.