Search

Protein gel of soy was formed immediately during polymerization of aniline initiated by certain amount of FeCl3. In order to obtain iron-doped carbon material, this composite was then carbonized at 700°C under nitrogen atmosphere for 5h. SEM, FT-IR, XRD, and isothermal desorption/adsorption technologies were employed to characterize morphology and structure of the material. Electrical capacitance of iron-doped carbon materials and performance of a prototype supercapacitor based on the material as its electrodes were measured by cyclic voltammetry, chronopotentiometry, and A.C. impedance respectively. Results show that morphology of as-obtained material is porous and hierachical, specific surface area of the material is 232.1m2/g, and specific capacitance of the material can reach 475.2F/g in 6 M KOH aqueous solution. Energy density and power density of the cell is 2.1Wh/kg and 2.0kW/kg, respectively. Capacity retention of the device is 100% after 5000 cycles at a current density of 2A/g. The above studies imply that this original iron-doped carbon material will have a good potential application in field of energy storage.

In order to study the preparation of low-melting alloy powder in phase change materials, three sets of control experiments were set up in this paper. To explore the effects of ultrasonic oscillation, ultrasonic atomization technology and rapid cooling had an effect on the particle size, surface morphology and powder shape of ultrasonic powder making. In the experiment, ultrasonic atomization, rapidly cooling ultrasonic atomization, and ultrasonic vibration generated powder were tested. The results showed that the surface of fog droplets generated by ultrasonic atomization was smooth, with distinct particles. The powder diameter was large, ranging from 20-60 μm. The surface of the powder obtained by ultrasonic shock existed an aggregation phenomenon. The powder diameter was small ranging from 5-10 μm. The ultrasonic atomized powder obtained by rapid cooling was mostly spherical with a smooth surface. After the screening, spherical powder with a diameter of 15-25 μm and the smooth surface could be obtained. The results showed that the particle diameter is small and uniform, while the uneven surface was difficult to eliminate. The experimental conditions of rapid cooling were favorable for the smoothness of the particle surface and the roundness of powder shape. Spherical powder with a diameter of 15-25 μm can be obtained by screening the rapidly cooled powder after ultrasonic atomization. Different experimental conditions and technological approach can produce high-performance low melting point alloy powder.

Barium titanate/graphene oxide/polyurethane (BTO@GO@PU) composite membranes for microwave absorption were designed and fabricated by mechanical-blending of BTO and GO in PU medium, followed by mold formation. The cross section morphology of the BTO@GO@PU membrane indicated that the BTO nanoparticles with 450 nm average diameter are successfully incorporated into the PU matrix. Mechanical tensile measurement showed that, as the amount of BTO nanoparticles increased from 5 wt% to 20 wt%, the elastic modulus of the corresponding membrane increased up to 23.0 MPa elongation with the elongation above 450 %. Microwave absorption property of the BTO@GO@PU membranes were evaluated by measuring its reflection loss in the frequency range of 0.1-18 GHz. With the addition of BTO up to 20 wt%, the maximum absorptivity of the composite reached up to 51 %. This is attributed to the dielectric loss of BTO nanoparticles.

In this study, a new green approach has been developed for the recovery of tungsten by using tungsten carbide (WC) scrap material as consumable anode in LiCl-KCl molten salts at 773 K to produce metallic tungsten. The feasibility of the direct electrochemical dissolution of WC anode into metallic tungsten was evaluated based on the experimental verifications and electrochemical methods. The effects of the main technical parameters, including the cell voltage, electrolysis time and electrolysis temperature, on the dissolved condition of anode were studied and the optimal anode parameters were obtained. It was found that a large electrolytic voltage, high electrolytic temperature and long electrolysis time would be favorable for the dissolved state of the tungsten carbide anode under the same conditions. The cathode product was analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the tungsten particles with a diameter of 100 nm could be prepared by this process in a molten salt bath. Linear sweep voltammetry was applied to investigate the dissolution of WC anode, and showed that the WC scrap material could be used as consumable anode to produce tungsten powder. Other electrochemical techniques including cyclic voltammetry , square-wave voltammetry and chronopotentiometry were employed to explore the electrochemical properties of tungsten ion derived from WC anode in LiCl-KCl melts. These results confirmed that electroreduction of tungsten ion in the melts proceeded in one step with four exchanged electrons.

The basic mechanical performance of glue laminated timber (GLT) reinforced with glass fiber reinforced plastic (GFRP) for structural materials was studied. The differences of mechanical performance of the GLT reinforced with GFRP and the common GLT were compared by the test, and the quantitative influence of reinforcement ratio and arrangement pattern of GFRP on the mechanical performance was investigated. The test results showed that the static bending strength of GLT increased with the increasing of GFRP reinforcement ratio, and the reasonable arrangement pattern of GFRP could improve the internal bonding strength of GLT. The influence of reinforcement ratio and arrangement pattern of GFRP on the elastic modulus was relatively small. Finally, a mathematical model of static bending strength for GLT reinforced with GFRP was proposed, which can consider the influence of reinforcement ratio and GFRP arrangement pattern

The 3D simulation of tufted carpet pile loops need to calculate the direction loop pile. By simplifying the tufted carpet yarn into elongated elastic rod, without considering the extrusion between loops piles, applying pressure at both ends of loop pile. By analyzing the elastic rod stress deformation and using Matlab simulate to determine the yarn centerline direction with the flexible line. The simulation results show that the obtained yarn centerline path is consistent with the trend of actual loop pile.

The optical and electric transport properties of the Al:ZnO(AZO) and (Cu, Al):ZnO (CAZO) films deposited by pulsed laser deposition (PLD) were investigated in this paper. The experiment found the optical band gap (OBG) of AZO films at room temperature increased from 3.378eV of ZnO to 3.446eV of ZnO:Al (2min) sample, but decreased as continue add Al to ZnO:Al (4min), which were attributes to the Burstein-Moss (B-M) effect. For CAZO films, there is obvious change about hall mobility,ν, and resistivity,ρ, after doped Cu. It can be found that theνdecreased from to and theρincreased from to for AZO and CAZO, respectively, which is due to the scattering increasing between donor carriers and grain boundary as Cu2+ions increase, meanwhile, it was also found the decrease of OBG, which are very help to further understand the electric transport properties and the OBG effect of AZO-based films as well as its devices potential application.

Model design and rapid prototyping are utilized to manufacture push-ups frame. Point cloud data can be obtained by scanning parts with hand-held laser scanner, and imported into the Imageware to process. The varied points are removed, the missing points are repaired, and then the 3D model is designed through the Pro/E. Finally, the frame model is completed by rapid prototyping printers. The manufacturing period is shorten through the way of putting two technologies in the field of manufacturing together, the production requirements are met, and the business efficiency is improved.

The properties of heat resistance and manufacturability of epoxy resin system are contradictory to each other. In order to maintain the balance of both properties, this article studied the heat resistance (testing the glass-transition temperature using differential scanning calorimetry) and the manufacturability (characterizing the variation trend of viscosity at molding temperature using AR2000EX rotational rheometer) of two kinds of epoxy resin systems by means of designing orthogonal table. Studies show that when the mass ratio of hydantoin epoxy resin, MF-4101 epoxy resin, anhydride and accelerant is 100:20:150:1.5, the glass transition temperature of the epoxy resin system can reach over 180°C. What’s more, the initial viscosity of the epoxy resin at 40°C is about 230mPa•s, and the viscosity can maintain no more than 800mPa•s in approximately 3 hours, which meets the requirements of liquid composite molding.

Accurate surface modeling of washing liquid bottle is to get through RP technology. Point cloud data of washing liquid bottle is obtained by hand-held laser scanner and processed by Imageware software, 3D model is got by Pro/E. Rapid prototyping machine is used to print solid model. High precision model built by ABS is easily got without complex processes.

Through detailed investigation to development status of grouting technique, summarizes the classification of geotechnical grouting technology, selection of materials grouting, Finally, by anchoring engineering and tunneling engineering described in detail grouting process，grouting order, grouting parameters and grouting end standard in the geotechnical engineering application，This research has practical guidance and theoretical reference value for similar projects.

We selected a typical filter material for high voltage electrostatic filter composite horizontal collector. Air filter can achieve high speed. It cost very low and can endure high temperature resistance. Removal of fine particles of dust effect is good. Solving the complex problems of higher smoke temperature conditions of traditional bag house can not handle, while reducing the dust collector investment cost, promote the development of China's dust remover industry.

In this study, we illustrated enhanced biodegradation enzyme activity and the strains growth using the plants residues as carriers during the biodegradation of phenol in petrochemical wastewater. The three phenol-degrading strains named as A1, A2 and A3 were selected for an immobilized microorganism technique. A1, A2 and A3 were identified asPenicilliumoxalicum,Aspergillussp. andSphingobacteriumsp. using detailed morphological, biochemical and molecular characterization. The growth and degradation rate of phenol in wastewater by strains A1, A2 and A3 pre-grown in the agricultural residues (peanut shell) were higher than the free strains. Compared with the free strains,the enzyme activity of strains A1,A2 and A3, using the residues for pre-grown, increased 29.01 U/L, 30.30 U/L and 38.07 U/L, respectively. Hence, the immobilized microorganism technique is conducive to the phenol degradation.

Compare and analysis the transient identification in Nuclear Power Plant fault diagnosis method. According to how does these methods for nuclear power plant systems HTR effect, Further proposed to a problem that towards existing transient recognition of methods to verification effectiveness. Preliminary analysis of the three kinds of validation strategy, after a comparative demonstration, it is formed the preliminary research on the utility analysis framework. Utility to verify the framework for the Nuclear Power Plant fault diagnosis methods carry out intensive research provides a theoretical basis.

s:Hebei’s Coal-fired generating Unit PM2.5 Emissions on Coal-fired generating Unit were estimation according to the method from “Technical Specifications of power industry and cement sector’s PM2.5 emissions (consultation)”. Quantitative analysis the relation of boiler tonnage, installed capacity, coal consumption with PM2.5 emissions.

The typical structure of energy management system for new electric vehicle was analyzed to summarize the function. The research trend was pointed out based on the analysis of performance characteristics of energy management system for electric vehicle.

The photosynthetic pigments of Sagittaria sagittifolia, including total chlorophyll content, chlorophyll a content, chlorophyll b content and carotenoid content, were investigated after 0, 7, 14 and 21 d exposure to 3 mg L-1 P. After 7 d P-exposure, total chlorophyll content, chlorophyll a content and chlorophyll b content increased significantly compared with the control, and then decreased with time extended. Carotenoid content increased significantly after 14 d P-exposure compared with the control, and then decreased slightly after 21 d P-exposure.

This article focuses on peat soil ofthe region of the Dian Chi Lake inKunming, the peat soil as research subject. This paperstudy on unconfined compressive strength test of solidifiedpeat soil mainly. In the experimental study of chemical admixtures curing peatsoil, the test hadeight groups. The experimental study of cement soil of different kindsof additives, and study the impact of additives on curing peat soil. It was concluded that the regularof cement soil compressive strength with the increases of chemical admixtureand curing time.

In the process of working, storage, finished fodder acceptance and the preservation process of grass materials, the moisture content of forage is a very important indicator. The blast oven drying method has been generally adopted in the measurement of moisture content. The related experiment showed that the microwave oven method for grass moisture content measuring improved 200-400 times in the efficiency compared with blast oven drying method. The microwave oven method was accurate and easy operating. So, we can conclude that microwave oven method is a viable method for measuring the moisture content.

Sagittaria sagittifolia was grown in nitrogen (N) stress monoculture to test the relative content of three pigments by the manipulative indoor experiment. The treatment consisted of one level of N (14 mg L-1 N) of nutrient solution. The content changes of three pigments were studied in continuous 21days. Results showed that the content of pigments was significantly increased at the first 7 days. With N stress increasing in the medium, the content of pigments decreased slowly. After 21 d N-exposure, the content of pigments were still higher compared to the contol.

For the vast rural areas in our province with complex terrain, the centralized sewerage facilities are backward, but the integrated equipments in wastewater treatment can be effectively applied to these places. As a decentralized wastewater treatment technologies, the use of the integrated equipment in wastewater treatment is more and more wide. The technology of itself is also becoming more complete. This paper concludes and summarizes the technological developments and applications of the integrated equipment in wastewater treatment from abrod to home,from single to complicate, analyses the shortages of the integrated equipments in wastewater treatment;and introduces the development of the integrated equipments in wastewater treatment.

Plate-like Sr3Ti2O7powders with anisotropy were prepared by KCl molten salt synthesis (MSS) method, the effect of different SrCO3/TiO2ratio and calcination condition on the phase transition, particle size and morphology of powders were investigated. The results show that SrTiO3phase coexist with Sr3Ti2O7phase and SrTiO3is the main phase as the SrCO3/TiO2ratio is 1.15~1.25:1. Pure Sr3Ti2O7phase can be obtained as the SrCO3/TiO2ratio is 1.55~1.65:1. The aspect ratio of plate-like particles increases firstly and then decreases as the SrCO3/TiO2ratio increases. The sealed and unsealed condition has no influence on the phase structure of the powders. But the aspect ratio of unsealed particles is smaller than that of sealed particle. Finally, the formation mechanism for Sr3Ti2O7particles was discussed.

This paper shows a method to calibrating the non-uniformity of the x-ray backscatter image in a side-beam x-ray detection system. The flying spot of x-ray beam cross the luggage under detection per cycle, and every point of the detector being irradiated by flying spot can be taken as an assumed detector. Using calibrators of different thickness and combined with the corresponding mathematical model, the greyscale of the image is uniformed and calibration is achieved.

In order to accomplish navigation and path planning, map building is the key technology and fundamental problem in mobile robotic control in unknown environment. In this paper the topological map is built based on the grid map by using a thinning algorithm. The environment is modeled in grid map, next the thinning algorithm is applied in the map, and then the effective topological information is extracted. Simulation results show that the topological map based on thinning is clear and succinct, and it also avoids producing unnecessary nodes and paths. This topological map stores much less information which will improve the ability of autonomous operation, navigation and path planning further.

Ground penetrating radar (GPR) is a powerful tool for detecting defects behind reinforced concrete (RC) structures. However, the received data from GPR includes a large number of clutters which are easy overwhelming the signal of target. In order to successfully extract the target signature, these clutters effects need to be eliminated. In this article, a clutter suppression algorithm based on Principal Component Analysis (PCA) combining with gradient magnitude is presented. PCA clutter suppression algorithm is applied to the data and removes most of the echoes from ground surface and portion of other clutters with weak energy. Then gradient magnitude clutter suppression is used to remove majority of the residue clutters. It is demonstrated from simulation that the proposed algorithm is able to significantly suppress the clutters and is superior to the PCA clutter suppression, magnitude clutter suppression and means subtraction method.

In this paper, the optimization of context weighting coefficients are studied and the objective of the optimization is to find a group of weighing coefficients, such that the code length ofsource symbols occurred before the current symbol can be minimized. Multivariant optimization algorithm is used to find the solution of this multimodal optimization problem. With this context weighting algorithm, the compression efficiency is improved.

Soil profiles from 0 to 80 cm depth were collected at five typical zones (including permanently flooded floodplain (B), 1-year floodplain (O), 5-year floodplain (F), 10-year floodplain (T), and 100-year floodplain (H)) which are divided by different flooding frequencies along the direction penperdicular to the river channel in different floodplain wetlands of Xianghai National Nature Reserve of China. A 14-day incubation experiment was carried out at 25°C in the dark to reveal the effects of different flooding frequencies on nitrogen mineralization rates. Our results showed that nitrogen mineralization rates showed an alternative tend of “increasing and decreasing”in the soil profiles at five sampling zones except the 1-year floodplain and permanent floodplain. The nitrogen mineralization rates were lower in permanently flooded floodplain soils compared to another four floodplain wetlands with different flooding frequencies. Additionally, nitrogen mineralization rates were significantly correlated with electrical conductivity, total soluble salt, pH values and salinity.

Visual C++6.0 is selected as development tools while Access 2000 of Microsoft is used to build database, and the technology of ADO is adopted to achieve the connection between them. Though the secondary development of API function provided by SolidWorks, the query module is taken as a plug-in integrated in SolideWorks, which achieves the automatic query.

By studying the performance of carbon anode oxidation protective coating, which main component is alumina, adjusted coating formulations, determined the optimum coating formulation under certain conditions. Heating texting method was adopted to test sample performance, study showed that the new oxidation protective coating on the surface of the carbon anode can be uniform and dense.

Emission of coal dusts can cause serious air pollution in coal-pile storage yard, which poses a threat to human health. Therefore, the quantitative research on particulate emissions is the premise for dealing with atmospheric pollution. In this paper, a series of experiments are firstly carried out in wind tunnel to study the impact of the wind velocity and water content on coal dusts for the mixing pile. Moreover, particle entrainment is investigated by measuring the velocity required to pick up particles from rest, also known as threshold velocity. Then a number of experimental data are obtained and a fitting formula is derived with the aid of Matlab. Finally, the results are compared with those published previously, and explanations about the differences are given.

This paper concerns the trajectory planning and simulation for 6R Manipulator. First, algebraic method was used to deduce the forward and inverse kinematics of 6R manipulator. All inverse solutions were expressed in atan2 to eliminate redundant roots to get the corresponding inverse formula. For the trajectory planning of manipulator in Cartesian space, using the cubic spline interpolation to get the drive function of joint, getting a unique solution from eight group inverses by the shortest distance criterion, and then obtained the actual end-effector trajectory. Using Matlab to verify the proposed trajectory planning method, validated results show that the proposed algorithm is feasible and effective.

A statistical analysis is made on papers published in Geomatics and Information Science of Wuhan University from 2001 to 2010 in terms of the number of published papers, the statistics of key words frequency, the number of published papers of authors, the regional distribution of authors, the number of co-authored papers, the added number of paper authors and active author group. The research direction of geomatics and the scale and trend in which geomatics researchers have cooperated in past ten years is represented. It is reflected that the Journal has played an important role in the information transmission, experience exchange, talents training and the improvement and development of China’s geomatics cause.

Yarns modeling are the key problem for tufted carpet 3D visual simulation. This paper deals with three-dimensional yarns structure modeling for tufted carpet simulation. The yarn is modeled as an assembly of fiber bundles which also include of a lot of fibers. to simulate fiber bundle dividing fiber bundle into many segments along its trajectory, and each fiber paths displayed are generated by NURBS curves. Through control the control points and color of NURBS to get certain cross-section and color effect of fiber bundle outlook. And finally use the fiber bundle to form the final yarn model. Test result shown the modeling method is suitable for carpet simulation.

Temporary bracing is often viewed as an unnecessary step in the process of constructing a structural facility. Unfortunately, many times this often-neglected step becomes the subject of avoidable litigation and lawsuits. This paper presents a remedy case of a deep foundation pit during the construction of the bracing system located at the business center in HePing district, TianJin. Through frequent inspection and suitable countermeasures, the potential disaster was mitigated in time. There were some lessons learned from this case history.

With the use of statistical methods processing the data,we measure and analysis the quantify environmental carrying capacity of Qujiang new District basing on constraints of control indicators, adjust the industrial structure and layout of their productivity, development and utilization of social and economic development goals, and resources on the development of proposed scientific, rational, innovative proposals and implement measures to prevent over-exploitation of resources and the environment, and promoting sustainable development in the region. Provide reference, help for the continued development of high-tech zones, technology parks and other areas in the southern suburbs of Xi'an, creating livable, prosperous Xi'an.

Damping property analysis of laminated composite structures have been done based on the complex stiffness method (CSM). In view of laminated plates with viscoelastic material cores, investigation is conducted using CSM and numerical methods of finite element method and spectral finite element method. Simulation results show that analytical solutions by CSM are in good agreement with the two kinds of numerical solutions. The proposed analytical method is well suited to calculate and optimize the damping property of laminated structures especially composites with constrained layer damping treatment.

A study for electrocatalytic hydrogenation of oxalic acid has been reported using the self-organized TiO2 nanotube electrode prepared by anodic oxidation method. The prepared electrode was characterized by SEM and XPS. The electrocatalytic activity of the TiO2 nanotube electrode was evaluated by CV and galvanostatic electrolysis. The CV studies and electrochemical experiments showed that TiO2 nanotube electrode exhibited high electrocatalytic activity. In addition, the surface of TiO2 nanotube electrode developed into a periodic lattice of nanopores after electrolysis, which makes it find a potential application as electrocatalysts.

Transition metal carbonyls are novel catalysts.This study examined the removal effect of COS over Fe2(CO)9 at atmosphere pressure compared with the removal of CS2 over Fe2(CO)9 at atmosphere pressure.By experiment contrast analysis,the removal effect of COS better than the removal effect of CS2. It shows that the existence of CO without producing competition.The removal effect of COS basically maintain the level of 60%~80% is good at atmosphere pressure.Then analyzing of Reaction mechanism, there are three kinds the interaction between Fe2(CO)9 and COS at atmosphere pressure are listed.There is every reason to believe that Fe2(CO)9 can make COS activation.

Sm2Co17:Cu,Crfilms growing on Cr buffer layer and Cu seed layer were prepared by pulsed laser deposition(PLD) methodbased on Si(100) substrate. The results showed that Cu and Cr co-doped in SmCo films made the refinement of crystal grain and the increase of coercivity of SmCo. Beside, the experiments found that the incorporation of Cu and Cr in SmCo films resulted in a positive effect of the exchange bias for SmCo-CuCr system. We suggested that the mechanism of the exchange bias origins from the interaction of ferromagnetic-antiferromagnetic state (FM-AFM, SmCo-CuCr). Meanwhile, the magnetic measurment of added magnetic field and zero-field-cooled (FC-ZFC) at temperature range of 10K~300K has further confirmed the critical value of FM-AFM tansform is about 80K, which is suggested that it was attributed to the coupling competition of FM phase and AFM phase.

This paper describes the speed regulation of a magnetic gear integrated permanent magnet synchronous motor. The operating principle of the motor is discussed and the torque transmission is analyzed using finite element method; hence the motor model is established. The speed regulation is analyzed under vector control, and the simulated results verify the feasibility of speed regulation control.

With the development of the Internet, people come to use it frequently to search bus lines, such as Google maps, Baidu maps, etc. But these online maps have the information only about bus lines, stops, but the information how long bus will arrive. The paper designs a bus monitoring and searching system to forecast bus waiting time. The system sets up Radio Frequency Identification Technology (RFID) equipment at every bus stop to identify the dynamic information and exchange data with buses on the road; Rely on Global Positioning System (GPS) technology, we obtain the real-time location of the target vehicle information, and through the geographic information system (GIS), the system show the condition of the vehicle and the road network in the electronic map which helps bus companies to monitor easily. Using the Android software, designed for users, users can check waiting time any time any where. The waiting time error in the system is less than two minutes.

Supercapacitors have been emerged as an important energy storage device, owing to their high power density, excellent cycle ability, fast charge-discharge processes and low self-discharging. In this work, we have developed a facile soft-templated hydrothermal procedure to produce hollow mesoporous carbon spheres, which can deliver a relatively high capacitance (~190 F/g) and an energy density of ~26.38 Wh/kg at the discharging current of 1 A/g. The hollow cavity and micropore volume are shown to be the main factors that contribute to the good capacitive behavior.

The control system uses pyroelectric infrared sensor as the detecting element, STC89C52RC microcontroller as the control core, to detect and determine the direction of human movement, demographics and intelligent control of indoor appliances. This control system has simple structure, reliable performance, low cost, it can be used in homes, school classrooms, large venue and other places, has good prospects. This article elaborates from the working principle, hardware circuits, program design and other aspects.

OA (Office Automation, OA) has been developed rapidly in the 1970s and introduced into China. In the 1990s, it has entered the high-speed development stage. With the rapid development of mobile internet technology, it will be a trend to apply such a high-tech to office automation. Meantime, there has introduced the workflow development approach to development in the overall system implementation. This thesis presents strategy on design and implementation on workflow based mobile office automation. With the rapid development of mobile internet technology, it will be a trend to apply such a high-tech to office automation. Meantime, there has introduced the workflow development approach to development in the overall system implementation. This thesis presents strategy on design and implementation on workflow based on mobile office automation.

This paper makes a summary of pattern matching algorithm in Intrusion Detection System: KMP algorithm, BM algorithm and BMH algorithm algorithm. The performances of various algorithms are analyzed, and then through the experiment data is verified. Last an improved algorithm based on the BM algorithm: BMD is proposed. BMD algorithm can reduce the space complexity and maintain the time complexity by reducing a pretreatment function and recording the number of times that a bad char found in the pattern.

This paper expounded the principle of using Fast Fourier transform measuring the phase difference and completed the simulation of measuring the phase differences of a plurality of signal. The simulation results show that the method can rapidly and accurately realize the phase difference measurement without considering the AD quantization error and noise interference. In considering the AD quantization error and random noise, Fast Fourier transform measuring the phase difference still has high measurement accuracy, and the measurement error can be controlled within 0.01°. The method can be applied in practical engineering.

The hydraulic support is mainly used in roadway and workplace for supporting and protecting in mining industry. The hydraulic support would appear the situation of declining, dumping and crowding on greater tilt angle mining face, these will threat the safety of the workplace, the safety of mining face is the key to the safety in production. This paper analyzes the reasons of declining, dumping in static force, gives respectively the angle range of working surface hydraulic support declining and dumping, proposes some relevant measures of the hydraulic support declining and dumping.

The PID parameters tuning is to determine the proportional coefficient Kp, integral time Ti and differential time Td of the regulator. It is a very complicated and cumbersome process. This paper describes the strategy and the steps of the critical proportion method, and completes the simulation of PID parameters tuning by using the critical proportion method in the MATLAB/Simulink. The simulation results verify the effectiveness and feasibility of the method. Using the software to tune PID parameters can easily modify the simulation parameters, save a lot of computation and programming, and greatly reduce the workload.