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Based on the weight averaged method, the variety of the PZT thin film is determined by combining nanoindentation test with finite element method (FEM) simulation, and the piezoelectric constitution is used to establish the supplemental equation, in which the piezoelectric strain constants are related with the piezoelectric stress constants, so that all of the piezoelectric constants of piezoelectric thin film can be determined by combining nanoindentation test and FEM. In the forward analysis, the numerical loading curves at the broad spectrum of possible material combinations are simulated by using ABAQUS software to extract the numerical maximum indentation loads and loading curve exponents, and they are used to establish two dimensionless equations related with the engineering/piezoelectric constants of film/substrate system. In the reverse analysis, the loading part of experimental indentation curves performed on PZT thin film in nanoindentation test are fitted as the power function to obtain the maximum indentation loads and the loading curve exponents, and the engineering constants can be solved by using the simultaneity of dimensionless and supplemental equations. In order to verify the validity, the optimized engineering constants are inputted into ABAQUS software to obtain the numerical loading curves, and they are compared with the engineering constants of PZT thin film measured by the previous method to determine the variety of the PZT thin film. The piezoelectric constants of the certain variety are determined by combining forward analysis and inverse analysis. The engineering constants of the PZT thin film are determined as ET = 142 GPa, EL = 137 GPa, GL = 52 GPa, and the PZT thin film is determined as PZT-6B. The piezoelectric constants of the PZT-6B are determined as e15 = 4.75 C/m2, e31 = −0.85 C/m2, e33 = 7.08 C/m2. The proposed method is effective to determine the engineering/piezoelectric constants of piezoelectric thin film.

A method using finite element method (FEM) is proposed to evaluate the geometry effect of indenter tip on indentation behavior of film/substrate system. For the nanoindentation of film/substrate system, the power function relationship is proposed to describe the loading curve of the thin film indentation process due to substrate effect. The exponent of the power function and the maximum indentation load can reflect the geometry effect of indenter and substrate effect. In the forward analysis, FEM is used to simulate the indentation behavior of thin film with different apex angles of numerical conical indenter tip, and maximum indentation load and loading curve exponent are obtained from the numerical loading curves. Meanwhile, the dimensionless equations between the loading curve exponent, the maximum load, elastic properties of film/substrate system and apex angle of indenter are established considering substrate effect. In the reverse analysis, a nanoindentation test was performed on thin film to obtain the maximum indentation load and the loading curve exponent, and then the experimental data is substituted into the dimensionless equations. The elastic modulus of thin film and the real apex angle of indenter can be obtained by solving the dimensionless equations. The results can be helpful to the measurement of the mechanical properties of thin films by means of nanoindentation.

The traditional nanoindentation method provides experimental data for the calibrating mechanical parameters of nanobelt through semi-empirical formulae. In this paper, a technique to identify Young’s modulus of nanobelts with different aspect ratios is introduced combining finite element method (FEM) and nanoindentation test. For the nanobelt on the substrate, the power function relationship is used to describe the loading curve of the nanobelt indentation behavior. The loading curve exponent of the power function which is the fitting parameter can reflect the influence of aspect ratio of nanobelt on Young’s modulus of nanobelts as well as the maximum indentation load. In the forward analysis, considering the substrate effect and the size effect, the numerical loading responses are simulated at the appropriate penetration depth, and then the dimensionless equations between the parameters characterizing the indentation loading curve and the properties of nanobelt/substrate system can be established via extensive FEM simulation. In the reverse analysis, the nanoindentation tests were performed on ZnO and ZnS nanobelts, and the experimental indentation loading curves can be fitted as power function. The maximum indentation loads and the loading curve exponents are extracted from two experimental loading curves, and then they are substituted into the dimensionless equations to solve the Young’s moduli of ZnO and ZnS nanobelts. The results show the Young’s moduli solved are close to previous values, indicating that the Young’s moduli are reasonable. This developed method is effective to identify the Young’s modulus of nanobelt and it can be applied to identify the Young’s modulus of other nanobelts in practice.

We develop the nanoindentation method to identify the elastic parameters of transversely isotropic thin films by combining nanoindentation test with finite element method (FEM) simulation. In the forward analysis, CAX4R and CAX4E element types of ABAQUS are used to simulate the purely mechanical indentation and the piezoelectric indentation. With assistance of the substrate effect, the numerical results give indentation responses at the moderate ratio of penetration depth to film thickness, and the dimensionless equations between the maximum indentation load, loading curve exponent and the elastic parameters of film/substrate system are established by extensive FEM simulations. In the reverse analysis, the nanoindentation test is performed on ZnO thin film as transversely isotropic material, and the experimental indentation curves can be fitted as the power function. The maximum indentation load and the loading curve exponent can be obtained from the experimental indentation curves and substituted into the dimensionless equations to obtain the elastic parameters of ZnO thin film. The results show the transverse Young’s modulus, the longitudinal Young’s modulus, and the longitudinal shear modulus under the piezoelectric indentation mode are closer to the experimental values measured by the acoustic method than those under the purely mechanical indentation mode. This study develops the nanoindentation method to extract the elastic parameters of transversely isotropic thin films, and it may be helpful to the measurement of thin film mechanical properties by means of nanoindentation.

A method to evaluate the substrate effect quantitatively in film indentation is proposed. For the thin film deposited on the substrate, the power function relationship is used to describe the loading curve of the film indentation behavior. The loading curve exponent of the power function which is the fitting parameter can reflect the substrate effect quantitatively. The finite element method is used to simulate the nanoindentation process of the film/substrate system. The loading curve exponent can be obtained from the simulation results. A substrate effect factor based on the loading curve exponent is defined to characterize the effect of the substrate on film indentation. Meanwhile, the dimensionless function of the loading curve exponent related with the material properties and indentation depth is obtained. The results can be helpful to the measurement of the mechanical properties of thin films by means of nanoindentation.

Pig slurry, urine and fermented liquid manure were evaluated measuring electrical conductivity (EC), dry matter (DM) contents and other components. Samples were collected during a period from February to April, 2001: slurry samples from 70 storage tanks, urine samples from 19 and 20 fermented liquid manure samples from 109 pig farms in Jeju. Samples were analyzed for pH, EC, DM, NH4 -N, K, P, Ca, Mg, Na, BOD, S-S, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn and OM. Relationships between EC or DM and various mineral and NH4-N contents were examined using linear regression. EC, DM, all mineral contents and NH4-N were higher in slurry samples than in urine or fermented liquid manure. EC, NH4-N, Ca, Mg and Na concentration was similar in urine and fermented liquid manure, but K and DM values in liquid manure were twice as much as in urine. P concentration was higher in urine than in liquid manure. NH4 -N and Na in slurry, NH 4-N in urine and NH4-N, P and Ca in fermented liquid manure were highly correlated with EC, while NH4 -N, P, Ca and Mg in slurry, NH 4 -N and Ca in urine, and K, P, Ca, Mg, and Na in fermented liquid manure with DM (P

Based on the key technology of wireless communication systems-Orthogonal Frequency Division Multiplexing (OFDM), an efficient joint algorithm is proposed. We exploit a training sequence to estimate the integer frequency offset and channel parameters, and lower the peak-to-average power ratio by using the data of the training sequence as the coefficients of partial transmit sequence (PTS) algorithm. Results of simulations indicate that this method can simultaneously realize frequency synchronization, channel estimation and the low peak-to-average power ratio by using one training sequence. The OFDM system with the proposed algorithm has better BER performance and can be implemented with improved validity and reduced redundancy information.

The synthesis of LaCrO3 and LaCrO3-based materials by the hydrothermal method and in air has been investigated. In respect to the synthesized products, the structure and a number of physical properties, such as electrical and magnetic properties, are discussed. The authors utilized the doped LaCrO3 material as various “conducting leads” for ZrO2-based heating elements to substitute the expensive Pt-Rh wire. The working temperature of these elements can be up to 2000–2100°C in oxidizing atmosphere.