Search

A biaxial test model was established based on the discrete element method to simulate the microscopic evolution of non-viscous soil upon loading. The shear strain, deviator stress and volumetric strain of the samples at different time steps were recorded, the evolution process of the force chain in the samples was observed, and the average degree (coordination number), 3-cycle and average clustering coefficient over force-chain particles were also analyzed respectively from the perspective of complex network. The following analysis results are obtained. The larger the value of inter-particle friction coefficient, the higher the peak value of shear stress, and the more obvious the strain softening phenomenon. The force chains in the samples with higher inter-particle friction coefficient tend to be more vulnerable to damage during loading. In the loading process, the average degree first increases, then decreases and finally tends to be stable. The value of average degree increases with the increase of confining pressure, and decreases with the increase of friction coefficient. The clustering coefficient of the particles within the force-chain particles is linearly related to the average length of the force chains at critical state.

This study investigated the effects of silage additives on the anaerobic digestion performance of hybrid penisetum to produce methane. Specifically, we evaluated the effects of adding lactic acid bacteria (0, 1.0×105, 1.5×105, 2.0×105 cfu.g-1) and cellulase (0, 0.01, 0.02, 0.03 g.t-1) during ensilage for 45 days on biogas production of hybrid penisetum. The silage additives lactic acid bacteria (1.0×105cfu.g-1, 2.0×105cfu.g-1) and cellulase (0.03g.t-1) had a positive effect on the anaerobic fermentation performance of hybrid penisetum silage. The hybrid penisetum amended with 0.03 g.t-1 of cellulase showed the best biochemical methane potentials, with a methane yield of 218.15lN kg-1 ODMadded. The results of this study clearly demonstrate that type and concentration of additives influence biogas production by silage.

Ecological compensation is being applied to deal with transboundary external effects caused by water resources conservation or exploitation in China. A concept of water resources co-conservation and sharing was applied to burden the upstream conservation cost and to share the benefit in the whole river basin. Xin’an River Basin, related to two provinces in East China, was taken as the study area. The current territorial scales of the co-conservation area and the benefit sharing area were determined. The total actual water conservation cost for Xin’an River Basin was estimated to be about 488 million CNY in 2006. By analyzing the transformation of protection costs and benefits between different districts and sections, benefits brought by water to different beneficiaries were also estimated. The conservation cost was distributed to the water users or governments in the whole sharing area according to the proportion of shared benefits.

Themicro-grid technology is an effective way to promote renewable energydevelopment and utilization. Low voltage micro-grid can absorb photovoltaic,wind power and other large number of scattered random distributed power supply,and the system may be three-phase asymmetry while operation, randomness of thepower output and load is stronger. Therefore an improved bidirectional power flow algorithm is putforward suitable for low voltage micro-grid. According to the physicalstructure components of the micro-grid and different kinds of micro powersupply, the types of micro-grid in power flow calculation is studied to dealwith complex node in the micro-grid, improved Zbus algorithm is proposed tocalculate the power flow of micro -grid .IEEE-69 is taken as an example for simulation, the resultsshow that the proposed method is better for the biggest error ratio of voltagedrop and calculation time than traditional method. Atthe same time the algorithm is also suitable for island operation state of the microgrid.

With the 2407 and VC33 double DSP system as the foundation of hardware, the basic idea is using a modified voltage model, implementation, and equivalent amplitude and phase characteristic of integral operation. Motor steady-state operation, the rotor counter electromotive force signal is a sine wave. And an ideal sinusoidal signal frequency for omega after integral link operation, output phase lag, amplitude to times. Observations can be found from the experiment of flux linkage and rotor counter electromotive force signal on the output phase and phase is obtained by pure integral part still have a little deviation, it will need a further study on the compensation link, how to make the compensation phase completely equivalent to the integral effect. From the point of the results of the experiment of 5 Hz low speed estimation error, verify the theory in this paper. One step closer to the test is more slow speed estimation.

The paper is about synthesizing the 2-ethylhexyl nitrate (2-EHN) with nitric acid and 2-Ethyl hexanol as raw materials and sulfuric acid as catalyst in a micro-channel reactor. The best synthetic conditions were determined under experiments: 1:2 for the mole ratio of nitric acid and sulfuric acid; 1:1 for the mole ratio of nitric acid and 2-Ethyl hexanol, the optimal liquid hourly space velocity is obtain as 4000h-1. In this condition, The yield and purity of EHN are Relatively high. This method is simple in process, mild conditions, safe, reliable and low energy consumption, providing the theory basis for industrialized production.

As sentence level sentiment analysis having been studied extensively, it has been proven that the syntactic structure of a sentence usually holds important information for sentiment analysis, especially for handling polarity reversal. However, the previous attempts of adopting such structural information mainly focus on making certain predefined rules which requires large linguistic expertise of the rule-maker,and the procedure itself is often manually labored and time consuming. To solve this problem, in this paper we propose a novel simple vector model to represent a sentence’s syntactic structure and its prior sentiment information uniformly and rapidly. Experiment results show that our proposed approach performs well in COAE 2013 dataset, and could also be used for machine learning algorithms to extract more distinguish features automatically.

The aim of this paper is to develop a kind of copper matrix self-lubricious material with excellent friction and wear characteristics. The copper-graphite composites reinforced with short copper-coated carbon fibers (CF-C/Cu) were successfully developed using techniques of mechanical alloying, composite plating and hot press vacuum sintering. For comparison, copper-graphite composites without short copper-coated carbon fibers (C/Cu) were made under the same process. The wear testing was carried out using a rapid wear testing machine (M-200).Friction coefficient was measured by a micro-wear tester (UMT).The microstructure, abrasive dust and worn surface of the wear pins on the different condition such as load and wear time were examined by SEM. It was noted that the addition of copper-coated carbon fiber in the Cu-based composites can retard the transformation process which transforms from micro-cutting wear to adhesive wear and delamination. The abrasion loss of the composites with short copper-coated carbon fibers appeared a valley when the load increased from 10N to 30N. It showed that the addition of copper-coated carbon fiber enhanced the anti-friction and anti-wear property of copper matrix composite and better than the sample without carbon fibers.

In order to overcome the defects of the high computational loads and selecting the threshold of mean square error (MSE) for time domain decision-directed constant modulus blind equalization algorithm (DD+CMA), a frequency domain parallel decision multi-modulus blind equalization algorithm based on frequency domain MMA(FMMA) and frequency domain LMS (FLMS) algorithm is proposed. The proposed algorithm is composed of the FMMA and FLMS, and the FMMA and FLMS run automatically in soft switching parallel manner. In running process, it is not necessary to selecting the threshold of the MSE. Moreover, the computational loads can be reduced by circular convolution in the frequency domain signals instead of linear one of the time domain signals. Simulation results show that performance of the proposed algorithm outperforms the FLMS and the FMMA algorithm.

The aim of the system is to achieve query expansion. The method works combining clustering of hierarchical methods. Through the information proffered by a background document, doc_ID, concerning the initial query, a cluster containing doc_ID can be produced by hierarchical clustering. And the word co-occurrence information can be extracted from the candidate documents in this cluster. Compared with the content in doc_ID, the result of the experiment using the system shows an expected performance to develop expanded terms which are qualified to add to original query.

Chitosan/Poly (vinyl alcohol) (CS/PVA) composite nanofibrous membranes with diameter between 150-350 nm have been fabricated by electrospinning. The effect of contact time, temperature, pH and concentration of triclosan on the adsorption capacity of the membranes were investigated. The equilibrium adsorption capacity of triclosan on CS/PVA nanofibrous membranes was 61.61 mg/g. The favorable pH for triclosan adsorption was pH 6. After five regeneration cycles, the removal rate of triclosan maintained above 67%. The adsorption of triclosan on the membranes fitted both Freundlich and Langmuir isotherm model. Its adsorption kinetics followed a pseudo-second-order model.

In this paper, a new method that extracting and fixing load characteristic curve in the power system network state estimation is proposed, based on the combination of The data mining technology in the critical meams assorts algorithm and effective index standards. In the course of the study, this paper put forward a new algorithm ,which simulates used matlab software programming and combined with the actual load data, and extracts load characteristic curve for amended. Revised characteristic curve will serve as a typical load model used to add system state estimation of pseudo measure. The simulation results fully support that the proposed method is rational and effective.

An automatic human motion tracking algorithm based the connection between the improved Snake model and optical flow arithmetic is proposed. The initial contour most close to human body is acquired by corner detection arithmetic, which decreases the iterations and reduces the probability of converging at local extreme value of Snake model. Because the tracking with Snake model is unstable and often loses the object, the good feature points are chosen from the contour points in current frame for optical flow estimation. Then the result is chosen as the initial contour in next frame. Experimental results show that improved Snake model can be deformed to the actual human body contour, and the automatic and real-time human tracking is implemented.

Gleeble 3500 thermo mechanical simulator was used to perform hot compression tests of GW103K (Mg-10Gd-3Y-0.6Zr) magnesium alloy at a temperature range of 573K-723K and strain rates of 0.001-1. The workability of the alloy can be evaluated by means of processing maps on the basis of dynamic materials model (DMM) and the superior processing condition is selected. Combining true compression stress-strain curves with the results of microstructure observation, it was found that the peak stress decreased observably as the decrease of strain rate and the increase of deformation temperature. Constitutive equation is built to reveal the accurate relationship among flow stress, temperature and strain rate.

Recently, the Euler strut is used as the supporting spring in the low frequency isolation. An Euler spring is a column or strut of steel material which is compressed elastically beyond its buckling load, which makes the ratio of the isolated mass to the mass of the supporting spring maximum, and greatly increasing the internal resonant frequencies of the isolator. In this research, the unique mechanical properties and the expressions of the displacement transmissibility of the Euler strut are deduced. The influences of structural parameters of the strut on the stiffness and vibration isolation characteristics are investigated in detail. The results show that the Euler strut has the potential in low frequency vibration isolation, and the length and breadth of the strut can influence the stiffness, transmissibility and critical loading mass respectively.

Meta-aramid/poly (acylic acid) (PMIA/PAA) composite nanofibrous membranes with diameter between 50-100 nm have been fabricated by electrospinning method. The effect of contact time, temperature, pH and concentration of 2,4-dichlorophenol on the adsorption capacity of the membranes were investigated. The equilibrium adsorption capacity of 2,4-dichlorophenol on PMIA/PAA nanofibrous membranes is 251.61 mg/g. Acidic pH was favorable for the 2,4-dichlorophenol adsorption. Its desorption rate reached 74% in 45 min. After five regeneration cycles, the removal rate of 2,4-dichlorophenol still maintained above 65%. The adsorption of 2,4-dichlorophenol on the membranes fit the Freundlich isotherm model best. Its adsorption kinetics followed a pseudo-second-order model.

Overall elastic-plastic stability behavior of cable-stayed ultra-high strength steel (660MPa) column with welded I-section is studied by geometric and material nonlinear FEM of software ANSYS. Longitudinal residual stresses and initial imperfections are taken into consideration. The results indicate that cable-stayed type can significantly improve overall stability bearing capacity and effectively control mid-span deflection of ultra-high strength steel column.

In order to discuss more convenient the relationship of coating morphology and frictional wear in processing, according to the one correspondence of gray image and actual surface topography, this proposed a method of digital image processing. with binary image of different load F and serial rubbings obtained pits distribution rate T and the optimal range in wear resistance. It calculated fractal dimension D based on the Discrete Fractional Brownian Random Field, summarized the osculating relationship of D and surface topography in frictional wear.

This paper introduces an acquiring and processing system of a new type of optical spectrometer based on vision technology. It mainly introduces the hardware structure to acquire the spectrums dispersed by the spectrometer, and the multi-spectrum image processing software as well. Of the different spectrum wavelengths ranges from 400nm to 740nm, the system can create both the color image and the 68 channels gray scale image. Virtual instruments technology is introduced into this system and it makes programming easier and faster by combining virtual instrument and vision technology. The programming of the image processing software uses LabVIEW platform.

On the basis of generalizing the conception of river ecological compensation(eco- compensation) reasonably, according to river characteristics and people’s practice experience, the paper gives discussion on river eco-compensation mechanism from the angle of coupling system. By analyzing the characteristics during theoretical study and practical experience of river eco-compensation, to ameliorate the limitations, the paper describes the framework of effective river eco-compensation mechanism. For Xin'an River as an example, in the light of the present compensation theory, the author gives river eco-compensation mechanism overall framework based on co-construction and sharing ideas. Learning from the research progress and achievement of different areas, the paper gives typical examples analysis about trans-boundary river eco-compensation implementation on water quantity and quality joint operation level. Finally, the paper puts forward the improvement measures and further research emphasis of river eco-compensation.

Thiol-functionalized poly (acrylic acid)/SiO2 (PAA/SiO2) composite nanofiber membranes have been fabricated by a sol-gel electrospinning method and their adsorption capacity for Ag+, Cu2+ was investigated. Results showed the PAA/SiO2 fibers had a diameter between 300 nm-700 nm. FTIR results demonstrated that the mercapto groups have been introduced into the silica skeleton. The adsorption of Ag+, Cu2+ on the membranes fit the Redlich-Peterson isotherm model best. The equilibrium adsorption capacity of Ag+ (575.64 mg/g) on PAA/SiO2 nanofiber membranes is higher than Cu2+ (331.52 mg/g). The desorption rate reached 98% in 30 min. The removal rate of Ag+, Cu2+ still maintained above 75% after six regeneration cycles. Adsorption kinetics of Ag+, Cu2+ followed a pseudo-second-order model.

The primary goal of this research is to keep the good performance of the LANs communications pass through the five categories of unshielded twisted pair. This is a working theory based on the idea that is to illustrate the optimizing character of Hub-spoken topology. The foundation and the features of Hub-spoken topology and the five categories of unshielded twisted pair are explained in detail. The concept of the dependable margin motion coefficient was put forward on the basis of the margin motion coefficient and the reliability coefficient. This research aims at providing the best solutions of Hub-spoken topology to improve performance of the LANs communications.

The corrosion inhibition of 45# mild steel in 3%HCL solution by norfloxacin has been studied by weight loss measurement, Tafel polarization, electrochemical impedance spectroscopy (EIS) and quantum chemical study. The inhibitor of norfloxacin shows 93.2% inhibition efficiency at optimum concentration 400mg/L. The polarization studies suggest that norfloxacin is the mixed-type inhibitor for 45# carbon steel in 3%HCL. Electrochemical impedance spectroscopy techniques are also used to investigate the mechanism of corrosion inhibition. What is more, the adsorption model obeys Langmuir adsorption isotherm at 298K. And the calculated quantum chemical also suggests that norfloxacin have excellent inhibition properties.

A new robust structured light technique based on multi-valued pseudo-random color encoded pattern is discussed in this paper. After analyzing the advantages and disadvantages of the existing pseudo-random coding patterns in computer vision, a new multi-valued pseudo-random color encoded pattern is designed on the basis of the combination of the feature points and the feature lines. Using this pattern, the feature points are easy to extract, and the problems of leaking points and pseudo-feature points are greatly reduced. Furthermore, it also reduced the difficulty and the complexity of the feature matching because of the feature lines.

A measuring method of large sized workpiece based on SIFT algorithm is proposed in this paper. After the different image matching algorithms are compared, SIFT algorithm, which has much more robust, is introduced in detail. Then measuring platform is built, and large sized workpiece is measured by SIFT image stitching and image processing. The experiment proves that SIFT algorithm is viable and advantageous in the measurement of large sized workpiece. At last, the precision and affecting factors are analyzed.

In this paper, a real-time location and reset method of cylindrical FPSO is presented based on GPS. In this method, the coordinate system of PFSO is determined by three GPS locators installed on the platform. Then, through coordinate transformation according to the marine engineering coordinate system established before, we can get the displacement and the orientation of FPSO, so as to achieve its real-time location. Finally, this displacement and orientation information is assigned to relative thrusters, which are evenly distributed with an angle 22.5°on both sides of the “+” and “-” X and Y axis, according to the calculating results of the optimization model.

With the rapid development of the subgrade or the foundation over recent years in China, there is a growing tendency for tall building to orient its directions to the more numbers of plies, much higher and more complex in plane layout. Moreover, some buildings adopt tube structure or bundled tube structure and so on to diversified development. The changing-rigidity of ground or foundation has obvious effects on superstructure when the buildings act on much higher and huge type. Therefore, in view of this, taking the bundled-tube structure of super high building for example in the paper, the method, equal the bundled tube structure of super high building and its foundation to stiffening-thin wall-combination, is adopted, then based on the three-dimensional model, the rigidity of subgrade and foundation’s effect on superstructure are given by calculation with semi-analysis. The calculated result indicated that there exist remarkable influence on sideway of the top end, the sideway between layers, the warp of the tube and the stresses between the subgrade and the bottom of the foundation.