基于数据质量评价的目标估计

针对目标估计过程需要大量人工参与、自动化程度低的问题，提出了基于数据质量评价的目标估计方法。利用目标数据质量评价方法，对不同传感器得到的目标数据质量进行科学、有效的测度和评价，并根据质量得分动态调整各数据源在目标估计过程中所占的权重，从而减少人工干预，提高目标估计效能。仿真试验结果证明了该方法的有效性。     

Permeability differences based on three-dimensional geometrical information of void spaces

In this study,the permeabilities of Berea and Otway sandstones were measured under different confining pressures,and porosity was investigated through mercury intrusion porosimetry(MIP).The total porosities of the Berea and Otway sandstones were approximately 17.4%and 25%,respectively.Pore size distributions of each sandstone were almost the same,but the pores in the Otway sandstone were slightly narrower.However,the permeability of the Otway sandstone was smaller than that of the Berea sandstone by one order of magnitude.Three-dimensional(3D)void geometry and geometrical properties of the void spaces relevant to flow were compared to obtain the relation between the permeability differences and porosities of the two sandstones.The 3D geometrical analysis using microfocus X-ray computed tomography(CT)was performed,and the pore geometries of both sandstones were compared using the 3D medial axis(3DMA)method.Pore and throat radii,pore coordination number,tortuosity,number of connecting paths,connecting path volume,and other factors were determined using 3DMA.The Otway sandstone was characterized by a small effective throat/pore radius ratio.Based on the fluid flow mechanism,the lower effective throat/pore radius ratio results in a lower permeability induced by the fluid energy loss,which means that the 3D geometrical shape of void spaces affects the permeability value.     

Recursive least squares estimation methods for a class of nonlinear systems based on non-uniform sampling

Many dynamic processes in practice have nonlinear characteristics and must be described by using nonlinear models. It remains to be a challenging problem to build the models of such nonlinear systems and to estimate their parameters. This article studies the parameter estimation problem for a class of Hammerstein-Wiener nonlinear systems based on non-uniform sampling. By means of the auxiliary model identification idea, an auxiliary model-based recursive least squares algorithm is derived for the systems. In order to enhance the computational efficiency, an auxiliary model-based hierarchical least squares algorithm is proposed by utilizing the hierarchical identification principle. The simulation results confirm the effectiveness of the proposed algorithms.     

A fast procedure for the estimation of the hydrogen storage capacity by cryoadsorption of metal-organic framework materials from their available porous properties

In order to identify the best porous materials for the cryogenic physisorption of hydrogen, high-throughput calculations are performed starting, i.e., from the collected information in crystallographic databases. However, these calculations, like molecular simulations, require specific training and significant computational cost. Herein, a relatively simple procedure is proposed to estimate and compare hydrogen uptakes at 77 K and pressure values from 40 bar starting from the porous properties of MOF materials, without involving simulation tools. This procedure uses definitions for adsorption and considers the adsorbed phase as an incompressible fluid whose pressure-density change is that for the liquid phase at 19 K. For the 7000 structures from the CoRE MOF database, the average error of the predictions is only of 1% from reference values at 100 bar, with an SD of ±8%. This accuracy is lower than that from simulation tools, but involving lower computational cost and training.     

Design and analysis of a new wave energy converter based on a point absorber and a hydraulic system harvesting energy from waves near the shore in calm seas

The aim of this paper is to illustrate the design of a new wave energy converter, composed of a point absorber and a hydraulic system (power take off) and sized for recovering energy in calm seas from waves near the shore. The point absorber is consisting of a rectangular shaped buoy integrating a piston pump. The set buoy‐pump oscillates under the waves action and moves natural water in a closed circuit hydraulic system (power take off) composed of a piping connecting the piston pump itself, a pressurized reservoir, a hydraulic turbine and a discharge tank. The methodology adopted for designing the main constituents involves a 1D mathematical model, settled for understanding the motion of the buoy under the hypothesis of regular waves and fully developed sea, and a sizing procedure applied for the design of all the components of the hydraulic system. The project related to the Calabrian site of Cetraro (Mediterranean Sea—south Italy) led to designing a system with a 4 m large buoy, associated with a small 13 cm diameter micro Pelton turbine, so that more than 22 000 kWh could be recovered in a year.     

Review of lithium-ion battery state of charge estimation

The technology deployed for lithium-ion battery state of charge (SOC) estimation is an important part of the design of electric vehicle battery management systems. Accurate SOC estimation can forestall excessive charging and discharging of lithium-ion batteries, thereby improving discharge efficiency and extending cycle life. In this study, the key lithium-ion battery SOC estimation technologies are summarized. First, the research status of lithium-ion battery modeling is introduced. Second, the main technologies and difficulties in model parameter identification for lithium-ion batteries are discussed. Third, the development status and advantages and disadvantages of SOC estimation methods are summarized. Finally, the current research problems and prospects for development trends are summarized.     

Electric vehicle energy consumption modelling and estimation—A case study

Electric vehicles (EVs) have a limited driving range compared to conventional vehicles. Accurate estimation of EV's range is therefore a significant need to eliminate “range anxiety” that refers to drivers' fear of running out of energy while driving. However, the range estimators used in the currently available EVs are not sufficiently accurate. To overcome this issue, more accurate range estimation techniques are investigated. Nonetheless, an accurate power‐based EV energy consumption model is crucial to obtain a precise range estimation. This paper describes a study on EV energy consumption modelling. For this purpose, EV modelling is carried out using MATLAB/Simulink software based on a real EV in the market, the BMW i3. The EV model includes vehicle powertrain system and longitudinal vehicle dynamics. The powertrain is modelled using efficiency maps of the electric motor and the power electronics' data available for BMW i3. It also includes a transmission and a battery model (ie, Thevenin equivalent circuit model). A driver model is developed as well to control the vehicle's speed and to represent human driver's behaviour. In addition, a regenerative braking strategy, based on a series brake system, is developed to model the behaviour of a real braking controller. Auxiliary devices are also included in the EV model to improve energy consumption estimation accuracy as they can have a significant impact on that. The vehicle model is validated against published energy consumption values that demonstrates a satisfactory level of accuracy with 2% to 6% error between simulation and experimental results for Environmental Protection Agency and NEDC tests.     

Parameter identification for Wiener-finite impulse response system with output data of missing completely at random mechanism and time delay

In this paper, the parameter estimation issue of Wiener system with random time delay and missing output data is studied. The linear part of Wiener system is described by Finite Impulse Response (FIR) model. The mathematical formula of the Expectation Maximum algorithm to identify Wiener-FIR system that contains the random time delay and the nonlinear output data in missing completely at random mechanism is derived, which is never considered before. To obtain the unmeasurable intermediate variable in Wiener-FIR system, the idea of auxiliary model is adopted. The time delay and system parameters can be estimated simultaneously by this method. Numerical example and the identification of water tank system example are carried out, the effectiveness of the algorithm is proved.     

Application of large scale PIV in river surface turbulence measurements and water depth estimation

Large-Scale Particle Image Velocimetry (LSPIV) has emerged as a reliable technology to measure river surface flow velocity distribution and can be applied to estimate river discharge. Fewer studies have explored the capability of surface turbulence measurements using LSPIV. In this paper, LSPIV is applied to evaluate statistics of surface turbulence of a natural river. Turbulence measurements including velocity fluctuation, velocity spectra and the dissipation rate of turbulent kinetic energy (TKE) are validated by comparing with those measured by an Acoustic Doppler Velocimeter (ADV). Traditionally, estimation of stream discharge through LSPIV needs a secondary measurement to determine river bathymetry and water depth. A new method is presented here to demonstrate that for a fully developed and channel-controlled flow, the cross section geometry can be estimated from the combined measurements of surface mean velocity and the dissipation rate, following the Manning-Strickler formula. Therefore, river discharge can be estimated with LSPIV along with a calibrated Manning's roughness, without additional bathymetry survey. The proposed new method is applied to measure discharge in Milwaukee River (Milwaukee, Wisconsin, U.S.A.), which agreed well with data obtained from a nearby streamgage station.     

Influence of modified multi-walled carbon nanotubes on the mechanical behavior and toughening mechanism of an environmentally friendly granulated blast furnace slag-based geopolymer matrix

This study aimed to investigate the mechanical behavior of an environmentally friendly granulated blast furnace slag-based geopolymer matrix reinforced with modified multi-walled carbon nanotubes (MWCNTs). The modified MWCNTs were obtained using a modification method combining nitric acid and sulfuric acid and were then dispersed using sodium dodecylsulfate (SDS) as a dispersant. Two types and three concentrations of MWCNTs were mixed directly into the aqueous solution, sonicated, and then mechanically mixed with waste granulated blast furnace slag to form the geopolymer matrix. Raman and Fourier transform infrared (FT-IR) spectroscopy were used to evaluate the ordered structure and crystallization degree of the modified MWCNTs. Then, the dispersity of the modified MWCNTs was characterized using transmission electron microscopy (TEM). The compressive and bending strengths were measured to evaluate the mechanical behavior of specimens. Moreover, the polycondensation products, polycondensation degree, pore structure, and microscopic morphology of the geopolymer matrix were analyzed using X-ray diffraction (XRD), FT-IR spectroscopy, nuclear magnetic resonance (NMR), mercury intrusion porosimetry (MIP), and field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM-EDS). The experimental results showed that the incorporation of 0.1% functionalized MWCNTs had an optimal influence on the fluidity and mechanical behavior. The slump diameters of geopolymers with 0.1% functionalized MWCNTs with and without SDS were increased by 16.3% and 23.5%, respectively, compared with the reference geopolymer matrix. For geopolymer matrix samples at a curing age of 28 d, the compressive strength of geopolymers with 0.1% functionalized MWCNTs with and without SDS were increased by 16.3% and 17.6%, respectively. For the bending strength, the corresponding increases were 17.6% and 18.7%, respectively. It was found that functionalized MWCNTs could increase the degree of polycondensation, leading to a more traditional amorphous N-A-S-H phase, a finer C–S–H phase, more Q⁴ (2Al) and Q⁴ (3Al), and lower porosity. In addition, the propagation of micro-cracks in the geopolymers was inhibited by the incorporation of functionalized MWCNTs.