Piecewise Curve-Fitting Method for Measured Profile

Aim To determine the measured profile of a wheel in railway vehicle.Methods So- called piecewise curve-fitting method of the third derivative continuity is employed . Results The formulas of the piecewise curve fitting method were derived the curve-fitting profile of a wheel looks very fine and its first to third derivatives are also smooth.Conclusion The new piecewise curve fitting method is fine enough to fit the measured profile data of a wheel for the purpose of vehicle system dynamic analysis.

Prediction of Antifrccze Critical Strength of Infant Age Concrete

The rule of infant age concrete strength development under low temperature and complex affecting factors is researched. An efficient and reliable mathematical forecast model is set up to predict the infant age concrete antifreeze critical strength under low temperature at construction site. On the basis of the revision of concrete equivalent coefficient under complex influencing factors, least-squares curve-fitting method is applied to approximate the concrete strength under standard curing and the forecast formula of concrete compressive strength could be obtained under natural temperature condition by various effects. When the amounts of double-doped are 10% fly ashes and 4% silica fumes as coment replacement, the antifreeze critical strength changes form 3.5-4.1MPa under different low temperature curing. The equivalent coefficient correction formula of concrete under low temperature affected by various factors could be obtained. The obtained equivalent coefficient is suitable for calculating the strength which is between 10% to 40% of standard strength and the curing temperature from 5-20 ℃. The forecast value of concrete antifreeze critical strength under low temperature could be achieved by combining the concrete antifreeze critical strength value with the compressive strength forecast of infant age concrete under low temperature. Then the theory for construction quality control under low temperature is provided.

Implementation of Dynamic System Control Circuit Board Test System of Pure Electric Vehicles

The dynamic system control circuit board(DSCCB)is one of the most important components for dynamic system of pure electric vehicles. The current detection of the DSCCB is done manually, which is not only inefficient in the detection but also difficult to guarantee the data accuracy. In order to improve the detection efficiency and accuracy, a new testing system is designed by Labview. The total test time can be further reduced by about 75% compared with the results of the manual detection. In this paper, the three-parameter sine wave curve-fit algorithm theory is applied to the phase delay detection of the current sensor sampling circuit on the DSCCB. This method solves the problem of big error in the phase delay detection.

Applications of Chapman-Richards model to geotechnical engineering

In this paper,the Chapman-Richards model is adapted to best fit three types of nonlinear curves that are generally encountered in geotechnical engineering practices,i.e.the degree of consolidation versus time factor curves in one-dimensional consolidation and plane strain consolidation under strip loading,the compressibility and permeability curves of soft clay,and the geometry parameters of geosynthetic tube versus pumping pressure curves.The methods of determining unknown parameters using the Chapman-Richards model are fully demonstrated.It is found that the Chapman-Richards model has its range of applications in geotechnical engineering and may provide unique insights into the complexity of geotechnical problems.

Large Prismatic Lithium Iron Phosphate Battery Cell Model Using PSCAD

Presently, there are mainly two problems that prevent Electric Vehicles (EVs) from becoming popular against the Internal Combustion Engine Vehicles (ICEVs), namely: short range and too long to recharge the battery pack of the EV. Due to this, battery development is a crucial aspect to improve the performance of EVs. This progress requires dependable computer aided designs to model the characteristics of a battery accurately and reliably. This paper uses Power Systems Computer Aided Design (PSCAD) to create an equivalent runtime circuit model to observe the qualities of the Lithium Iron Phosphate battery cell under discharge at different temperatures. The model is a 3-R-C branch runtime equivalent circuit model. In order to find the fixed parameters of the circuit, MATLAB was used to implement basic current voltage characteristics. 3-D tables have been used in PSCAD to implement the State of Charge (SOC) and temperature dependent circuit parameters of the model. Once the simulations for all temperatures were completed, the average marginal error between measured and simulated terminal voltage came to be 2.1%, therefore making PSCAD an accurate simulation tool for modeling equivalent circuits of different batteries.

Estimating Gini Coefficient Based on Hurun Report and Poverty Line

Based on the review of various methods of estimating Gini coefficient, the paper applies a quintile rule to estimate Gini coefficient of rural areas, urban areas and the whole country using the grouped income data of urban and rural residents. Besides, the paper uses the curve-fitting method to roughly estimate Gini coefficient from eye-catching Hurun Rich List and the latest poverty line. The result shows that the estimation of Gini coefficient using quintile rule is small for both urban and rural area, while the value of the whole country is obviously larger, which is above the warning line of 0.4. It is indicated that the wealth gap mainly comes from the gap between urban and rural areas. On the other hand, the estimation of Gini coefficient using curve-fitting method is as large as more than 0.7, which implies that the wealth gap is?highlighted from the analysis of the lowest and highest part of the wealth distribution. All in all, China’s current gap between the poor and the rich is serious. The reform of the income distribution needs to speed up to ensure social harmony and stability.

Lung mechanics in canine oleic acid-induced respiratory distress syndrome model

In mechanically ventilated anesthetized dogs (pentobarbital sodium,30mg/kg) with acute lung injury induced by intravenous infusion of oleic acid(OA),changes in airflow,lung volume,and tracheal (Pao),transpulmonary (Ptp)and esophageal (Pes) pressures were measured.Changes in lung mechanics werestudied before and after OA infusion at intervals,during an observation periodlasting 4h,using curve-fitting method,interrupter technique and pressure-volume(PV) loops measurement.The main findings are listed as follows:(1)Complianceand functional residual capacity (FRC) showed a marked decrease,while Pao andPtp showed a marked increase within 2h after OA.(2) Airflow resistance atexpiratory phase estimated by the curve-fitting method showed a marked increaseafter OA.(3)PV loops of the lungs or total respiratory system showed similarchanges 4h after OA,characterized by the presence of an inflexion point at theinflation limb,increased hysteresis and rightward and downward shift of the loop.It is suggested that use of the curve-fitting method in combination with the PVloop for the total respiratory system would be more appropriate for monitoringlung mechanics during mechanical ventilatory support of ARDS patients.

Arm-Root Curve Fitting Based on Body Surface Feature Points for Young Male

This paper is aiming to obtain an arm-root curve function performing the human arm-root size and shape realistically. A gypsum replica of upper arm for young male was made and scanned for extracting the 3D coordinates of 4 feature points of shoulder point, the anterior/posterior armpit point and the axillary point describing the real arm-root shape under the normalized definitions, and the 5 landmarks were confirmed additionally for improving the fitting precision. Then, the wholly and piecewise fitting of arm-root curve with 9 feature points and mark points in total were generated respectively based on least square polynomial fitting method. Comparing to the wholly fitting, the piecewise fitted function segmented by the line between anterior and posterior axillary points showed a high fitting degree of arm-root morphology with R-square of 1, the length difference between fitted curve and gypsum curve is 0.003 cm within error range. And it provided a basic curve model with standard feature points to simulate arm-root morphology realistically by curve fitting for accurate body measurement extraction.

Polynomial Functions Composed of Terms with Non-Integer Powers

Polynomial functions containing terms with non-integer powers are studied to disclose possible approaches for obtaining their roots as well as employing them for curve-fitting purposes. Several special cases representing equations from different categories are investigated for their roots. Curve-fitting applications to physically meaningful data by the use of fractional functions are worked out in detail. Relevance of this rarely worked subject to solutions of fractional differential equations is pointed out and existing potential in related future work is emphasized.

Research on the Motion Track of Ocean Towing System

In this paper, a method for predicting the position of towline is presented. The location of the finite node is determined by installing fixed spaced attitude sensors in towline arrays, then the appropriate objective functions are selected for water depth profile and course profile respectively, and the interpolation fitting method is combined with the determined predicted positions. Through the hydrodynamic analysis of the existing towing cable’s underwater motion, the position of the towing cable under the steady state motion is obtained as the reference basis, and two methods are put forward, which are improved spline interpolation method, polynomial fitting method and multivariate nonlinear regression analysis. In the case of steady state motion, the two methods are compared and compared with the hydrodynamic simulation results. Finally, a more suitable method is selected as the basis of cable location inversion and applied to deep-sea towing operations.

Dynamic modeling and analysis of vortex filament motion using a novel curve-fitting method

Applications of a novel curve-fitting technique are presented to efficiently predict the motion of the vortex filament, which is trailed from a rigid body such as wings and rotors. The gov- erning equations of the motion, when a Lagrangian approach with the present curve-fitting method is applied, can be transformed into an easily solvable form of the system of nonlinear ordinary dif- ferential equations. The applicability of Bezier curves, B-spline, and Lagrange interpolating polyno- mials is investigated. Local Lagrange interpolating polynomials with a shift operator are proposed as the best selection for applications, since it provides superior system characteristics with minimum computing time, compared to other methods. In addition, the Gauss quadrature formula with local refinement strategy has been developed for an accurate prediction of the induced velocity computed with the line integration of the Biot-Savart law. Rotary-wing problems including a vortex ring problem are analyzed to show the efficiency, accuracy, and flexibility in the applications of the pro- posed method.

Determination of water states and the structural parameters of W/O microemulsions

The states of water in sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane/water reverse(W/O) microemulsions system have been investigated by using Fourier transform infrared spectroscopy(FT-IR) technique. The broad peak obtained for hydroxy(O-H) of water has been resolved by least square curve-fitting. It has been observed that the water solubilized in microemul-sion droplets has four states, i.e. bound water with sulfo-group, free water, bound water with sodium counterion in the water pool of microemulsion droplets and a small amount of trapped water in the palisade layer of microemulsion droplets. The following have also been determined: the aggregation number (n), the radius of the water pool in the microemulsions(rw), the thickness of the bound water with sulfo-group(d1), the thickness of the bound water with sodium counterion(d2), the total thickness of the bound water (d) and the effective area of head groups of AOT(AAOT).