Dynamics of TN and TP in the Backwater Region of the Linjiang River in the Three Gorge Reservoir

Based on monitoring data of water quality and river runoff from 2007 to 2008, the dynamics of TN and TP transported into the backwater region of the Linjiang River were investigated and fluxes of TN and TP were also estimated. It was shown that the dynamic changes of TN and TP were significant. The concentration of TP in rainy seasons was higher than that in dry seasons, while the cases for TN was contrary. The fluxes of TN and TP were significantly higher in rainy seasons than those in dry seasons. On average, there were about 4 142 t TN and 455 t TP transported into the backwater region of the Linjiang River every year. And TN flux decreased by 32.7% from 2007 to 2008, while TP flux increased by 34.3%, which was in agreement with the inter annual variation of the concentrations of TN and TP. TN flux was primarily influenced by river runoff, whereas TP flux was affected by both concentration and runoff. Further analyses indicated that TN was mainly caused by point source pollutants(dominated by NH3N, and then DON). On the contrary, TP was mainly caused by plane source pollutants(dominated by PO34P). It was also indicated that it was critical to control the point source pollution in the basin to promote the water quality of the backwater region of the Linjiang River.     

An improved method for and error evaluation of modal pushover analysis

Based on evaluation of the basic principle and error of the modal pushover analysis method, an improved method is suggested by selecting rational values of stiffness reduction parameters of beams and columns in a reinforced concrete frame corresponding to the global target displacement ductility ratio. A 10 story and a 16 story reinforced concrete plane frame are designed as examples to investigate the influence of higher modes. Nonlinear seismic responses of the two frames under excitations of seven earthquake waves of varying earthquake intensities are selected to be the reference points for a comparison study. The changing rules of the results of modal pushover analysis and modified modal pushover analysis with respect to various natural fundamental periods and different earthquake intensities are studied. Research results show that the error of modal pushover analysis and modified modal pushover analysis will not increase with a larger fundamental period, which implies that modal pushover analysis can cover the effect of higher modes reasonably. When the degree of nonlinearity of the structure is more severe, the modified modal pushover analysis we suggest could decrease the error of normal modal pushover analysis to a certain extent.     

Fetal electrocardiogram extraction based on radial basis function neural networks

A novel method for extracting fetal electrocardiogram (FECG) from the abdominal composite signal of a pregnant woman is proposed. The maternal component in the abdominal electrocardiogram (ECG) signal is a nonlinearly transformed version of the mother's ECG (MECG). This nonlinear relationship was identified using radial basis function (RBF) neural networks. The FECG is extracted by subtracting the nonlinearly transformed version of the MECG from the abdominal ECG signal. The baseline shift and noise in the FECG are suppressed by wavelet packet denoising technique. Experimental results obtained from the actual ECG signals demonstrate the effectiveness of the proposed method in extracting FECG even when it is totally embedded within the maternal(QRS) complex.     

Effect of humidity and temperature on power electric field intensity

We measure power electric field intensity at a substation in southwestern P. R. China at various humidity levels and temperatures. Measurement data and a back propagation neural network are used to construct a model of electrical field intensity responses to fluctuations in humidity and ambient temperatures. The maximum error is 0.047 5. The results show that the power electric field intensity increases as humidity rises when the temperature is constant; when humidity is a constant, temperature changes do not affect the regularity of the electric field intensity in a consistent manner regularly.     

A method for considering parameter errors in power system harmonic state estimation

Total least squares (TLS) is proposed to complete harmonic state estimation when parameter and measurement errors are both taken into consideration. The buses are partitioned into subsets of non source buses and suspicious buses, thereby reducing the number of unknown state variables. The validity and practicability of this approach is validated using the IEEE 14bus harmonic testing system. The estimation precision is analyzed by random sampling 10 000 times in Matlab when measurement errors and parameter errors followed a Gaussian distribution. The results show that an accurate estimate can be obtained using TLS if parameter and measurement errors are considered.     

Adsorption performance of orange residue absorbent to hexavalent chromium

We use an inexpensive adsorbent produced from orange residue found to remove the Cr(Ⅵ) from an aqueous solution. We investigate the factors influencing adsorption performance and the adsorption mechanism of the orange residue adsorbance of Cr(Ⅵ). The results show that the contact time, pH, and initial Cr(Ⅵ) solution concentration affect the adsorption process. At pH 4 and 40℃, the equilibrium is attained in about 11 hours, and adsorption quantity of the adsorbent is 12.85 mg/g with liquid/solid (hexavalent chromium vs. adsorbent) of 18 mg/g. The ideal saturated amount is 13.74 mg/g as determined by the linear least squares method. The adsorption process fits the Bangham adsorption kinetics model. At a low concentration range, the process also follows the Langmuir and Freundlich adsorption isotherms. Experimental results and the adsorption mechanism show that the orange residue adsorbent is an effective treatment for wastewater containing Cr(Ⅵ).     

X ray diffraction method of measuring microball coat thickness

Use of the X ray diffraction method to measure microball coat thickness is studied. A mathematical model of X ray diffraction of microballs is created and solved using computer aided simulation. The relationship between diffracted X ray intensity and coat thickness is calculated with the help of a standard sample possessing a known thickness. The coat thickness of other samples can be calculated by the intensity of diffracted X ray based on the same condition. The experimental result shows that this method is a rapid, convenient, non destructive means of measuring microball coat thickness.     

Energy consumption analysis and reconstruction of subway platform screen doors in northern cities for energy saving

To analyze the influence of the platform screen doors (PSD) on energy consumption of subway environmental control systems in northern cities and to make good use of piston wind, EnergyPlus, an energy analysis and thermal load simulation program, is used to evaluate such systems in northern cities. A computational fluid dynamics (CFD) simulation is made to model the velocity and temperature field of a subway station and to predict the effect on PSD reconstruction using Airpak. Compared to a system with automatic platform gates, a PSD system has 2% lower energy consumption. Thus, PSDs are inefficient for saving energy in northern cities. Because electricity consumption by ventilation equipment increases notably when PSDs are used, particularly by under platform exhaust fans, little difference exists in the overall energy consumption with or without PSD. More thoroughly using piston wind in transition seasons and the winter is the key to solving the high energy consumption problem. The energy analysis and CFD simulation results show that the adjustable vents in PSD can use the piston process to introduce outside air, thereby reducing ventilation energy consumption notably. Because the vents can be closed, PSDs also can save energy in the summer. Using these recommendations can reduced annual energy consumption 30%.     

Anti sliding pile performance under acid stress coupling

Anti sliding piles are an important engineering structure used extensively in landslide prevention. Their durability influences their work lives. In a laboratory model experiment of a cantilevered anti sliding pile under acid stress coupling, the pile body displacement variation is monitored continuously, and both concrete strength and neutralization depth are tested. The results indicate that the concrete strength decreases gradually under acid stress coupling, while the displacement increases continuously. The neutralization depth of the concrete in the anti sliding pile is linear to the square of duration in acid stress coupling.     

Reproducing kernel particle method for numerical analysis of Mindlin plate bending on a Winkler foundation

The reproducing kernel particle method (RKPM) is a typical meshless method based on kernel function simulation. Based on the interpolating shape function of RKPM and Mindlin plate theory, the governing equations of RKPM to the deflection solution of Mindlin plate bending on a Winkler elastic soil foundation are established. Numerical results indicate that the above method and the corresponding program are effective and accurate.