The primary evaluation of the economic losses caused by water pollution in Shanghai in the year 2009 is made by classification approach in order to provide basis for decision of the relative water management policy. The result shows that the portion of water pollution losses in GDP of Shanghai was 2.7%, which was still lower than the average level of whole China despite of the local high population density and the scale of industry, suggesting to some extent the continuous attention in water protection paid by Shanghai government.
This paper presents a novel sideslip angle estimator based on the pseudo-multi-sensor fusion method. The kinematics-based and dynamics-based sideslip angle estimators are designed for sideslip angle estimation. Also, considering the influence of ill-conditioned matrix and model uncertainty, a novel sideslip angle estimator is proposed based on the wheel speed coupling relationship using a modified recursive least squares algorithm. In order to integrate the advantages of above three sideslip angle estimators, drawing lessons from the multisensory information fusion technology, a novel thinking of sideslip angle estimator design is presented through information fusion of pseudo-multi-sensors. Simulations and experiments were carried out, and effectiveness of the proposed estimation method was verified.
Heterogeneous nuclear ribonucleoprotein K (hnRNP K), is a multifunctional protein that participates in a variety of regulatory processes of signal transduction and gene expression. To further characterize the significance of hnRNP K in different male germ cells, we investigated the expression profiles of hnRNP K at different developmental stages in pig and rat testes, and conducted a comparative analysis of expression patterns between these two species. In porcine testis development, both the mRNA and protein level of hnRNP K were down-regulated from 3 months to 8 months. However, the expression level of hnRNP K was abundant across the embryonic period in rats, and decreased gradually from 0 day post partum (dpp) to 14 dpp, then increased with the highest level presenting at 90 dpp. Immunolocalization analysis further confirmed the differential expression and localization of hnRNP K protein during testis development in pigs and rats. The results showed that hnRNP K was widely distributed in gonocytes, spermatogonia, sertoli cells and Leydig cells. The dynamic expression profile of hnRNP K may imply its crucial and potential roles in the development of the testis, which will provide a theoretical basis for the future study of molecular mechanism regulation of spermatogenesis.
A mixed pseudo-orthogonal frequency coding (Mixed-POFC) structure is proposed as a new spreadspectrum technique in this paper, which employs frequency and time diversity to enhance tag properties and balances the spectrum utilization and code diversity. The coding method of SAW RFID tags in this paper uses Mixed-POFC with multi-track chip arrangements. The cross-correlation and auto correlation of Mixed-POFC and POFC are calculated to demonstrate the reduced overlap between the adjacent center frequencies with the Mixed-POFC method. The center frequency of the IDT and Bragg reflectors is calculated by a coupling of modes (COM) module. The combination of the calculation results of the Bragg reflectors shows that compared with a 7-chip POFC, the coding number of a 7-chip Mixed-POFC is increased from 120 to 144 with the same fractional bandwidth of 12%. To demonstrate the validity of Mixed-POFC, finite element analysis (FEA) technology is used to analyze the frequency characteristics of Mixed-POFC chips. The maximum error between designed frequencies and simulation frequencies is only 1.7%, which verifies that the Mixed-POFC method is feasible.
In this study, medium-carbon steel was subjected to warm deformation experiments on a Gleeble 3500 thermosimulator machine at temperatures of 550°C and 650°C and strain rates of 0.001 s–1 to 1 s–1. The warm deformation behavior of martensite and the effects of strain rate on the microstructure of ultrafine grained medium-carbon steel were investigated. The precipitation behavior of Fe3C during deformation was analyzed and the results showed that recrystallization occurred at a low strain rate. The average ultrafine ferrite grains of 500 ± 58 nm were fabricated at 550°C and a strain rate of 0.001 s–1. In addition, the size of Fe3C particles in the ferrite grains did not show any apparent change, while that of the Fe3C particles at the grain boundaries was mainly affected by the deformation temperature. The size of Fe3C particles increased with the increasing deformation temperature, while the strain rate had no significant effect on Fe3C particles. Moreover, the grain size of recrystallized ferrite decreased with an increase in the strain rate. The effects of the strain rate on the grain size of recrystallized ferrite depended on the deformation temperature and the strain rate had a prominent effect on the grain size at 550°C deformation temperature. Finally, the deformation resistance apparently decreased at 550°C and strain rate of 1 s–1 due to the maximum adiabatic heating in the material.
With the increasing penetration rate of grid-connected renewable energy generation, the problem of grid voltage excursion becomes an important issue that needs to be solved urgently. As a new type of voltage regulation control method, electric spring (ES) can alleviate the fluctuations of renewable energy output effectively. In this paper, the background and basic principle of the electric spring are introduced firstly. Then, considering the influence of an electric spring on noncritical load voltage, noncritical loads are classified reasonably, and based on the electric spring phasor diagram, the control method to meet the noncritical load voltage constraint is proposed. This control method can meet the requirements of voltage excursions of different kinds of noncritical load, increase the connection capacity of the noncritical load and improve the voltage stabilization capacity of the electric spring. Finally, through the simulation case, the feasibility and validity of electric spring theory and the proposed control method are verified.
In the present investigation, the morphology of Ti inclusions in high strength tire cord steel was investigated and their precipitation behavior was discussed using a precipitation and growth model. The results show that Ti inclusions mainly exist in the form of TiN. The two-dimensional characterization of Ti inclusions is square-like with sharp edges and corners, while its three-dimensional shape exhibits a cubic or rectangular-prism morphology. The Ti inclusions do not precipitate when the solid fraction of tire cord during solidification is less than 0.987, and their final radius is closely related to the cooling rate and initial concentration product. The higher the cooling speed, the smaller the final radius, when the cooling speed is constant, the final radius of Ti inclusions is mainly determined by the initial concentration product, w[N]0×w[Ti]0. In order to retard the precipitation and growth of Ti inclusions in tire cord steel, the cooling rate and initial concentration product can be taken into consideration.
As the most recent video coding standard, High Efficiency Video Coding (HEVC) adopts various novel techniques, including a quad-tree based coding unit (CU) structure and additional angular modes used for intra encoding. These new techniques achieve a notable improvement in coding efficiency at the penalty of significant computational complexity increase. Thus, a fast HEVC coding algorithm is highly desirable. In this paper, we propose a fast intra CU decision algorithm for HEVC to reduce the coding complexity, mainly based on a key-point detection. A CU block is considered to have multiple gradients and is early split if corner points are detected inside the block. On the other hand, a CU block without corner points is treated to be terminated when its RD cost is also small according to statistics of the previous frames. The proposed fast algorithm achieves over 62% encoding time reduction with 3.66%, 2.82%, and 2.53% BD-Rate loss for Y, U, and V components, averagely. The experimental results show that the proposed method is efficient to fast decide CU size in HEVC intra coding, even though only static parameters are applied to all test sequences.
Considering the low efficiency during the process of traditional calibration for digital-display vibrometers, an automatic calibration system for vibrometers based on machine vision is developed. First, an automatic vibration control system is established on the basis of a personal computer, and the output of a vibration exciter on which a digital-display vibrometer to be calibrated is installed, is automatically adjusted to vibrate at a preset vibration level and a preset frequency. Then the display of the vibrometer is captured by a digital camera and identified by means of image recognition. According to the vibration level of the exciter measured by a laser interferometer and the recognized display of the vibrometer, the properties of the vibrometer are calculated and output by the computer. Image recognition algorithms for the display of the vibrometer with a high recognition rate are presented, and the recognition for vibrating digits and alternating digits is especially analyzed in detail. Experimental results on the built-up system show that the prposed image recognition methods are very effective and the system could liberate operators from boring and intense calibration work for digital-display vibrometers
Recycling construction and demolition waste not only reduces project costs; and saves natural resources, but also solves the environmental threat caused by construction waste disposal. In this paper, C25 waste road concrete is used as an experimental material, the uniaxial compression strength and tensile splitting strength of C25 RAC whose coarse aggregate replacement rate is 0%, 25%, 50%, 75%, and 100% are tested under the condition that the water-to-cement ratio is 0.47, 0.55 and 0.61. The results show: (1) the uniaxial compression strength and tensile splitting strength decrease with the increase of RAC; (2) for concrete with the same water-to-cement ratio, when the coarse aggregate replacement rate changes from 0% to 50%, the uniaxial compression strength and tensile splitting strength of RAC changes slightly. When the coarse aggregate replacement rate changes from 50% to 100%, the uniaxial compression strength and tensile splitting strength of RAC decreases rapidly
The distortion of air gap magnetic field caused by the rotor eccentricity contributes to the electromechanical coupling vibration of the brushless DC (BLDC) permanent magnet in-wheel motor (PMIWM) in electric vehicles (EV). The comfort of the BLDC in-wheel motor drive (IWMD) EV is seriously affected. To deeply investigate the electromechanical coupling vibration of the PMIWM under air gap eccentricity, the PMIWM, tyre and road excitation are analyzed first. The influence of air gap eccentricity on air gap magnetic density is investigated. The coupling law of the air gap and the unbalanced magnetic force (UMF) is studied. The coupling characteristics of eccentricity rate, air gap magnetic density, UMF, phase current and vibration acceleration are verified on the test bench in the laboratory. The mechanism of the electromechanical coupling vibration of the BLDC PMIWM under air gap static eccentricity (SE), dynamic eccentricity (DE) and hybrid eccentricity (HE) is revealed. DE and HE deteriorate the vibration acceleration amplitude, which contributes the electromechanical coupling vibration of the PMIWM. The research results provide a solid foundation for the vibration and noise suppression of the PMIWM in distributed drive EV.
Reliable estimation of longitudinal force and sideslip angle is essential for vehicle stability and active safety control. This paper presents a novel longitudinal force and sideslip angle estimation method for four-wheel independent-drive electric vehicles in which the cascaded multi-Kalman filters are applied. Also, a modified tire model is proposed to improve the accuracy and reliability of sideslip angle estimation. In the design of longitudinal force observer, considering that the longitudinal force is the unknown input of the electric driving wheel model, an expanded electric driving wheel model is presented and the longitudinal force is obtained by a strong tracking filter. Based on the longitudinal force observer, taking into consideration uncertain interferences of the vehicle dynamic model, a sideslip angle estimation method is designed using the robust Kalman filter and a novel modified tire model is proposed to correct the original tire model using the estimation results of longitudinal tire forces. Simulations and experiments were carried out, and effectiveness of the proposed estimation method was verified.
Sound joint of hollow-extruded 6005A-T6 aluminum alloy was achieved by friction stir welding and its high cycle fatigue performance was mainly investigated. As a result, the joint fatigue limit reaches 128.1 MPa which is 55% of the joint tensile strength. The fatigue fracture mainly occurs at the boundary between the stir zone and thermo-mechanically affected zone due to the large difference in the grain size. This difference is caused by the layered microstructure of the base material. The shell pattern with parallel arcs is the typical morphology in the fracture surface and the distance between arcs is increased with the increase of stress level. The specimen with the fracture located in the stir zone possesses a relatively low fatigue life.
The effects of Mg and Ca on sulfide modification of sulphur steel were studied to elucidate the difference between micromagnesium treatment and micro-calcium treatment for the inclusion of sulphur steel. The results show that the inclusions in the steel appeared with an oxide core of Al2O3 and MnS wrapped. After the addition of Mg, the core was changed to spinel, and the MnS coating was changed to Mn-Mg-S. After Ca was added, the core was changed to Ca-Al-O, and the MnS coating was changed to Mn-Ca-S. The Mg content was higher than Ca content in the sulfides of the steel. Therefore, Mg was more effective than Ca in terms of sulfide modification with the same content of Mg and Ca in steel, but the yielding rate of Mg was lower than that of Ca. The Mg content in the oxide core was higher than Mg of the coating of the inclusions in the steel treated with Mg or Mg-Ca. In contrast, the Ca content in the oxide core was lower than Ca of the coating of the inclusions in the steel treated with Ca or Mg-Ca. MnS formed and precipitated during the melt solidification process. The complex sulfide (Mg-Mn-S) was precipitated around MgO·Al2O3 in the Mg treated steel during the cooling process. CaS inclusion was precipitated on the CaO·Al2O3 inclusions in the liquid Ca-treated steel. Thus, CaS was formed first, whereas MnS was formed during the cooling process, followed by the formation of complex sulfide (CaS+MnS), which finally precipitated around CaO·Al2O3 in the Ca-treated steel.
This paper proposes a soft sensing method of least squares support vector machine (LS-SVM) using temperature time series for gas flow measurements. A heater unit has been installed on the external wall of a pipeline to generate heat pulses. Dynamic temperature signals have been collected upstream of the heater unit. The temperature time series are the main secondary variables of soft sensing technique for estimating the flow rate. A LS-SVM model is proposed to construct a non-linear relation between the flow rate and temperature time series. To select its inputs, parameters of the measurement system are divided into three categories: blind, invalid and secondary variables. Then the kernel function parameters are optimized to improve estimation accuracy. The experiments have been conducted both in the single-pulse and multiple-pulse heating modes. The results show that estimations are acceptable.
Mg-0.5Si-xSn (x=0.95, 2.9, 5.02wt.%) alloys were cast and extruded at 593K (320 o C) with an extrusion ratio of 25. The microstructure and mechanical properties of as-cast and extruded test alloys were investigated by OM, SEM, XRD and tensile tests. The experimental results indicate that the microstructure of the Mg-0.5Si-xSn alloys consists of primary α-Mg dendrites and an interdendritic eutectic containing α-Mg, Mg2Si and Mg2Sn. There is no coarse primary Mg2Si phase in the test alloys due to low Si content. With the increase in the Sn content, the Mg2Si phase was refined. The shape of Mg2Si phase was changed from branch to short bar, and the size of them were reduced. The ultimate tensile strength and yield strength of Mg-0.52Si-2.9Sn alloy at the temperature of 473K (200 o C) reach 133MPa and 112MPa respectively. Refined eutectic Mg2Si phase and dispersed Mg2Sn phase with good elevated temperature stability are beneficial to improve the elevated temperature performance of the alloys. However, with the excess addition of Sn, large block-like Mg2Sn appears around the grain boundary leading to lower mechanical properties.
The heavy metal release experiments were conducted in the laboratory to examine the effects of 3 factors - pH, dissolved oxygen (DO), and temperature on the metal release from sediments taken from the Huangpu River. The metal concentrations in the dry sediments ranged from 0.030 to 0.296 mg g-1 for Cr, 0.021 to 0.097 mg g-1 for Ni, 0.014 to 0.219 mg g-1 for Cu, 0.035 mg to 0.521 mg g-1 for Zn, 0.0002 to 0.001 mg g-1 for Cd and 0.023 to 0.089 mg g-1 for Pb. Most of the metals found in the sediments were in the form of residual fraction, the exchangeable fraction consisted of only a small portion of total metals. The average dissolved metal concentrations in the overlying water during the 13-day period under different conditions were ranging from 0.82 to 1.93 μg L-1 for Cr, 1.08 to 4.19 μg L-1 for Ni, 40.79 to 82.28 μg L-1 for Cu, 20.30 to 29.96 μg L-1 for Zn, 1.57 to 4.07 μg L-1 for Cd, and 22.26 to 75.50 μg L-1 for Pb, respectively. Statistical interpretation of the data indicated that pH (7, 8, 9), dissolved oxygen DO (1.0 and 5.0 mg L-1) and temperature (4, 16, 25°C) had no significant effects on the heavy metal release under the studied conditions. Cu and Pb had the highest release flux, while Cd, Pb and Cu had higher mobility. The main factors controlling the metals release might be the inherent characters of metals and sediments.