Search

In the industrial control process, the controlled object usually has a serious time delay, time-varying, nonlinear, and a wide variety of interference is present, the use of conventional PID control method, it is difficult to obtain satisfactory dynamic and static performance. This paper introduces a fuzzy control theory for online use of PID parameters modified intelligent control method, the controlled system has a good dynamic characteristics, static characteristics and anti-jamming capability. The results of computer simulation in Matlab and experimentation show that the method is efficacious.

For the common highway bridge strengthening works, this article divides the evaluation of bridge strengthening works into three categories layers - durability, safety and suitability, to evaluate the bridge strengthening from a technical level. Then analyzed separately for each category layer, select the parameter indices which have an important influence on each category layer to be the evaluation indicators. When evaluating the safety and suitability, the durability has been taken into consideration to amend their evaluation scores. On the basis of the obtained scores of the category layers, by using the Analytic Hierarchy Process method and the weighted average method, we can get the evaluate score of the members, components, parts entirety and the entirety of bridge successively. Proposed a kind of post-evaluation method applies to the common highway bridge reinforcement. This post-evaluation method provides theoretical references for the effect post-evaluation bridge reinforcement.

In recent years, ZigBee technology is widely used in the greenhouse environment measurement and control system, however, its poor penetration and low anti-interference capacity limit its more applications. To solve these problems, a greenhouse environment measurement and control system based on super Wi-Fi was designed. In this paper the concept of super Wi-Fi is introduced, the superiority of super Wi-Fi is showed though comparing with several other communication technologies, protocol stack of super Wi-Fi is also developed. The structure of greenhouse environment measurement and control system based on super Wi-Fi is also introduced and terminal wireless sensor network node was designed, finally this paper draws the conclusion that this system has the features of long transmission distance, good anti-jamming, low power consumption,but it has poor real-time performance, which need to be improved.

In this thesis, we take STM32F103R8T6 as main chip, SH79F32 as auxiliary chip, the temperature sensor of DS18B20 as collection tools, wireless transceiver based on nRF905 as communication tool, and reach the function of wireless sensor networks. Through Altium Designer Release 10 to conduct schematic design and draw PCB, and then solder circuit boards, use the software of Keil to design process, to realize wireless sensor communication between different microcontrollers, after that ,complete the design and production of wireless sensor communications platforms.

Test of basic properties of steel fiber reinforced concrete (SFRC) was carried out to further study the validity of the binary superposition mix proportion method. The strength grades of SFRC were CF40, CF50 and CF60. The key parameters of the study were the fraction of steel fiber by volume, the thickness of cement paste wrapping steel fibers and the water to cement ratio. The workability of fresh SFRC was measured firstly to satisfy the construction requirement. The compressive strength, tensile strength and flexural-tensile strength of SFRC were tested simultaneously. Based on the test data, the changes of above basic properties of SFRC are analyzed in view of the effects of the fraction of steel fiber by volume and the thickness of cement paste wrapping steel fibers. It shows that the optimum thickness of cement past wrapping steel fibers is 0.8mm. The influencing coefficients in formulas for calculating tensile strength and flexural-tensile strength of SFRC specified in the current technical specification are given out.

With the growing amount of the chemical fertilizer consumption and agricultural wastes, non-point pollution of agriculture has been one of the problems threatening world crop production, especially considering the urgency of climate change. In this paper, a review of the research of biochar, pyroligneous acid and organic fertilizer mixture is given. And agronomic and environmental benefits that can potentially be derived from the application of this soil amendment in soils are discussed.

This article discusses biochar adsorption and its effects on soil and discusses the future trends in this area. The large surface area, and many oxygen-containing functional groups of biochar determined by the feedstocks and the condition in pyrolysis affect the capacity of biochar to adsorb fertilizer, water, heavy metals and organic pollution. With enriched porous structures, biachar can increase the porosity and water retention capacity of soils. With the functional groups and the composition, biochar have a high adsorption capacity for fertilizer, heavy metals, organic pollutants. This paper provides an overview on the biochar sorption in fertilizer, heavy metals and organic pollutants in soil and its implication for soil to keep soil fertilizer as a controlled-released carrier and to improve soil environments as landscaping organic mulch, as well as for remediation of contaminated soils. Further research directions are identified to ensure a safe and sustainable use of biochar as a soil amendment.

Firstly, The core model, structure module, performance characteristics and JTAG debug interface of the microprocessor were described by this article. Then, the system power supply module, prior to the passage weighing signal and tachometer signal circuits were designed in this paper. Secondly, according to the operational needs of the belt scale system, the external memory circuit and the TFT-LCD touch screen circuit modules were studied. Finally, the high-speed circuit board PCB designed to solve EMC problems. And it described the data collection and weighing controller bus communication test situation and established the communications test platform of Profibus-DP, introduced the test experimental procedures, experiment shows the communication between master and slave test results are correct.The computing speed and accuracy, data processing compared with traditional electronic belt scale, information exchange, integration, reliability and stability will be greatly improved by the advanced embedded technology and so on.

The precision plug tray seeder is mainly used to implement precision seeding, and it is the key equipment to accomplish the goal of mechanized and automated seedling in the greenhouse. The plug seedlings planter can greatly improve the productivity of labor and reduce labor intensity at the same time. The seed metering device is the core component of precision plug tray planter. Its performance directly influences the production, the sowing quality and the cost. The purpose of this paper is to introduce the study of the plug seedlings planter for domestic and abroad, and particularly Introduce three typical seeder (plate-typeneedle-likeroller-type). Keywords:Seeder;Seed Metering Device;Plug Seedlings;Greenhouse.

Hardware circuit design process with the motion control system of the traverse robot was described, including the motor drive module and the feedback module with location information. A large number of experiments showed that the modules could be well applied to the platform of the traverse robot.

In order to deal with the conflict of the robot high-performance implementing the task in an uncertain environment, environmental modeling method based on ultrasonic ranging was adopted. By the complex environmental modeling mean of combining the methods of grid and geometry, relying the measurement data of the adjacent multi-ultrasonic and the correlation among the data, the environmental modeling was established effectively. The modeling characteristics analysis showed that: the robot can easily make obstacle avoidance, path planning and decision-making in the grid-based modeling. The accuracy of the modeling is high, and it can detect and update the complex regional expediently. The environmental modeling based on ultrasonic ranging can effectively solve the problem of mobile robot implementing the tasks efficiently in the actual complex environment.

Considering the concrete as a three-phase composite material composed of aggregate, interface and cement matrix, an octagon unit cell is constructed based on ellipse, and the numerical solution of concrete chloride diffusion coefficient considering the aggregate shape is obtained using the finite element method. The validity of the proposed algorithm is preliminary verified after compared with the available test results, and the effect of interfacial crack opening angle and aggregate shape on the concrete chloride diffusion coefficient is quantitatively evaluated. Through numerical calculation, it is found that the chloride diffusion coefficient of concrete increases with the increase of interfacial crack opening angle and decreases with the increase of aggregate shape coefficient.

In this paper, an effective digital signal processing method based on the merger of the increasing and decreasing time-series sequences (MIDS) is introduced. On the basis of the merging of EEG signals, a new IED (Interictal Epileptiform Discharges) detection method is proposed. The first step of this new method is to establish a database by selecting peaked wave fragments. Then, the similarity between pending test fragment and peaked wave samples in the database is calculated. When the maximum similarity is greater than a certain threshold, the fragment is judged to be a peaked wave. Finally, the wave type i.e. spike wave, sharp wave, spike-and-slow wave or sharp-and-slow wave can be determined by whether there is a subsequent slow wave or not. Continuous sharp wave can be viewed as spike rhythm. In this research, 92 IED fragments from 4 suspected epilepsy patients are collected to establish the sample database. The proposed method was tested on EEG recordings from other 31 suspected patients. The results show that 98.11% of the IED fragments marked by doctors were detected. The experimental results show that this method performs well at IED detection in the clinical EEG data. The similarity is measured based on the comparison between fragments of different time length and can be viewed as a novel approach for the detection of typical EEG waveform. This research draws two conclusions: (1) the waveform of individual peaked wave is stable during 24-hour EEG recording process; (2) the database containing a small number peaked wave samples can be used to detect IED fragments.

This paper introduces the test results of the flexural performance of CF40 steel fiber reinforced concrete (SFRC) designed by the binary superposition mix design method. The flexural strength and flexural load ~ deflection curves were got from the test SFRC specimens with the different fraction of steel fiber by volume and the different thickness of cement paste wrapping steel fibers. The effects of the fraction of steel fiber by volume and the thickness of cement paste on the flexural strength and toughness of SFRC are analyzed. It is demonstrated that the flexural toughness of SFRC increases with the increase of the fraction of steel fiber by volume, the reasonable thickness of cement paste wrapping steel fibers is 1.0mm.

The tests were carried out to study the effects of the fraction of steel fiber by volume and the thickness of cement paste wrapping steel fibers on the axial tensile properties of steel fiber reinforced concrete (SFRC). The strength grade of SFRC was CF40 with the fraction of steel fiber by volume varying from 0.5% to 2.0%, and the thickness of cement paste wrapping steel fibers varying from 0.8mm to 1.2mm. The tests were conducted by WAW-600 electric-hydraulic servo-type test machine. The results show that the axial tensile properties such as the axial tensile strength, the fullness of stress-strain curve, the tensile energy and the axial tensile toughness ratio are all improved obviously by the adding of steel fiber in concrete. The reasonable thickness of cement paste wrapping steel fibers is 1.0mm. The formulas for stress-strain relationship of SFRC in axial tension are proposed.

With the full study of industrial process control technology for thermal, chemical industry, the application process, the FCS system of biomass pyrolysis unit was development combined with the actual. Feeding system uses the weighing system of dynamic belt with an advanced embedded technology. The computing speed and accuracy, data processing compared with traditional electronic belt scale, information exchange, integration, reliability and stability will be greatly improved. The technology shall be constantly upgraded and vigorously promoted. This paper introduces the control system based on Profibus-DP communication interface module of belt weighting device in transporting unit biomass pyrolysis system. Taking a PC, as a single master station system, and the data is transmitted from the master station to the slave station through the communication card. At the same time, the MCU+SPC3 are used to design the hardware interface circuit from the station. The mechanism of data polling transmission between a master and slave is conducted. Communication protocol of Profibus-DP is analyzed, and then, GSD file is compiled.

Polycarboxylate was synthesized by using polyethylene glycol monomethyl ether methyl-acrylate (PEG16), methylacrylamide sodium (MAS), methacrylic acid (MAA), methyl acrylate (MA), acryl amide (AM), and sodium persulfate (SPS) and evaluated as a superplasticizer for cement particles. The formulation of the superplasticizer: n (PEG16): n (MAS): n (MAA): n (MA): n (AM) =10:18:20:37:20, and the content of the SPS was 1.2wt% of all the monomers and optimized reaction conditions (80°C, 6h) were obtained via orthogonal test and single factor experiments. The water reducing effect of the synthesized copolymers was studied in terms of reaction temperature, reaction time and PEG side chain length. In this study, flow test of cement paste measurements were performed to compare the molecular weight effect on fluidity of the copolymers. It was observed that the reaction temperature had a noticeable effect on the molecular weight of the PEG-grafted samples thus causing a significant effect on fluidity. The polycarboxylate synthesized at about 80°C has given the highest fluidity result. In addition, the reaction time 6~7 hrs was identified for the best. Furthermore, copolymers with mPEG side chains with a degree of 16 gave the highest fluidity and viscosity average molecular weight value. The initial fluidity of the cement paste containing the prepared superplasticizer (1wt%, w(water)/w(cement)=(0.29)) was 316 mm.

With the full study of industrial process control technology for thermal, chemical industry, the application process, the FCS system of biomass pyrolysis unit was development combined with the actual. Feeding system uses the weighing system of dynamic belt with an advanced embedded technology. The computing speed and accuracy, data processing compared with traditional electronic belt scale, information exchange, integration, reliability and stability will be greatly improved. The technology shall be constantly upgraded and vigorously promoted. The frame structures of dynamic roller were various in forms. Different systems can be used to the frame with different scale structures. The suspension of multi-scale frame of the roller was used widely currently. The modeling and structural optimization of the frames in reasonable scale were designed with reducing the use of metal materials, optimizing the overall performance of mechanical systems and improving the weighing accuracy. The analysis of dynamic roller in scale weighing and speed principle, the establishment of a multi-roller single floating frame structure of the scale model and the analysis of the roller of the force were built. The verification in final design through the ANSYS software is reasonable.

In this paper, the finite element model of piezoelectric ceramics in line with the experiment results was established according to piezoelectric structure field and the coupling of the electric field, deformation of representative PZT piezoelectric ceramics under the voltage was analysed in using finite element analysis software ADINA according to establishing geometric model, defining boundary conditions and materials, Coupling calculation. Consistency between simulation results and experimental results is improved and lay the foundation for the realization of the piezoelectric ceramic shapes and vibration control.