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Extensive researches have been conducted over the decades to investigate the effects of seawater on many crop plants, either by irrigation or foliar spray, in an attempt to enhance yield and quality, but there are few studies on the effects of seawater irrigation on soil properties. The purpose of this study was to determine the effects of seawater irrigation on the fruit quality of Cabernet Sauvignon grapevines, soil pH, soil salinization, soil bulk density properties and soil microbial diversity. Field experiments were conducted using seawater (10% concentrations) during the fruit expansion period, the early veraison period, the veraison period and the late veraison period in Penglai (pH 6.5–6.7). Seawater irrigation led to increased levels of fruit soluble solids, phenolic content, anthocyaninand sugar/acid ratio, resulting in slowly-increased pH values of soils. After 4 years of continuous seawater irrigation, the pH value of the 0–20 cm soil layer increased 0.24 units at the vineyard of the Guobin Winery and increased 0.17 and 0.18 units after one and two years of seawater irrigation, respectively, at the vineyard of the COFCO Winery. Moreover, seawater irrigation did not affect soil properties, since soil bulk density, specific gravity and porosity did not differ significantly from the control soil. Furthermore, seawater irrigation had less effect on the types of soil microbial communities. The results suggest that combined with rainfall, seawater irrigation could be useful for improving fruit quality and soil pH without inducing secondary soil salinization problems, and seawater irrigation could be used in acidic vineyard soils.

Precession is a unique motion in which the orientation of the rotational axis of a rotating body is not fixed but moving, and it generally exists in the Universe from giant stars through tiny atomic nuclei. In principle, the precession of an atomic nuclide can be approximately described as wobbling motion, arising from the coupling of a rotation and a harmonic vibration. Recently, a number of wobbling bands were reported at low spin, which violate the wobbling approximation that can be valid only at high spin. Here we explore the nature of the reported low-spin wobbling bands. Via a new experiment, we demonstrate that one such band in $^{187}$Au is generated by dominant single-particle excitation rather than by the excitation of a wobbling phonon. We point out that the imperfect research paradigm used previously would lead to unreliable identification of low-spin wobbling bands. Consequently, new experimental approaches should be developed to distinguish among the different excitation mechanisms that can give rise to the observed low-spin bands in odd-even nuclei.

To study the relationship between the mechanical properties of sintered NdFeB magnets and composition of the Nd-rich phase, sintered NdFeB magnets with different mechanical properties and composition of Nd-rich phases were prepared by spark plasma sintering technology (SPS). Several correlations including the bending strength of the magnet to sintering temperature (σbb-t), the rare earth content in the Nd-rich phase to the sintering temperature (nRE-t), and the iron content in the Nd-rich phase to the sintering temperature (nFe-t) were investigated. Several empirical formulas for these relationships ware obtained by fitting these experimental curves. It is found that there is almost no change in the sum of Re and Fe content, revealing that the diffusion direction of RE and Fe atoms in the boundary phase between the main phases during sintering is opposite, and the relationship of σbb to nRE are approximately linear. Based on these, the mechanism of improving the mechanical properties of sintered NdFeB materials via changing the composition of Nd-rich phase was discussed.

β -FeOOH nanoparticles have been prepared in a microemulsion system with nonionic surfactant polyoxyethylene(4)nonylphenylether CH 3 (CH 2 ) 8 C 6 H 4 O(CH 2 OCH 2 ) 4 H. The powder X-ray diffraction, infrared spectra, and transmission electron microscopic images indicate that the products are 20–30 nm length nanorods with a crystal structure belonging to monoclinic β -FeOOH and lattice parameters of a =0.9981, b =0.2948, c =1.0485 nm and β =92.26°. The size and shapes of β -FeOOH nanoparticles can be manipulated by the surfactant. The modified β -FeOOH nanoparticles are paramagnetic at room temperature and may be antiferromagnetic or weakly ferrimagnetic at lower temperatures. The 57 Fe Mossbauer spectra show that the magnetic structure transforms below 150 K and two kinds of Fe–O octahedra exist in the lattice of the modified β -FeOOH nanoparticles. The numbers of each kind of Fe–O octahedra are not the same at room temperature or at low temperatures.

We have investigated the magnetic, electrical transport and electron spin resonance (ESR) properties of polycrystalline Fe-doped manganite LaMn 0.7 Fe 0.3 O 3+ δ prepared by sol–gel method. A typical cluster-glass feature is presented by DC magnetization and AC susceptibility measurements and a sharp but shallow memory effect was observed. Symmetrical Lorentzian lines of the Mn/Fe spectra were detected above 120 K, where the sample is a paramagnetic (PM) insulator. When the temperature decreases from 120 K, magnetic clusters contributed from ferromagnetic (FM) interaction between Mn 3+ and Mn 3+ /Fe 3+ ions develop and coexist with PM phase. At lower temperature, these FM clusters compete with antiferromagnetic (AFM) ones between Fe 3+ ions, which are associated with a distinct field-cooled (FC) effect in characteristic of cluster-glass state.

A laboratory-scale EMS-based HTS maglev vehicle operating over a 1.5 m guideway has been successfully constructed. The fully integrated system consists of a vehicle chassis, four dependent magnetic circuits, four distance sensors, and control and power amplification circuits. As key component of the system, each magnetic circuit includes a U-shape iron core with one HTS coil forming each pole. Eight HTS coils made of Bi-2223 multi-filamentary tape were used to provide the magnetic motive force. Several questions relating to the unique characteristics of the HTS material in a controlled magnetic circuit are discussed. The most important consideration for such applications is that the anisotropic critical current of the Bi-2223/Ag tape depends strongly on the magnetic field. The commercially available FEA software ANSYS was used to simulate the field distribution along the magnetic circuit and HTS coil winding, and thereby identify how the magnetic circuit alters the field distribution in the coil winding and therefore also the critical current. A general optimization process is described for finding the best position in the U-shape iron core to hold the HTS coils. In this process the critical current of the HTS tape and the force–current characteristic of the magnetic circuit are considered synthetically. The results demonstrate the feasibility and stability of HTS material in a typical maglev system and other similar controllability applications. � 2005 Elsevier B.V. All rights reserved. PACS: 84.71.Ba

The amorphous iron boron alloy can be prepared very easily by a room temperature solid–solid reaction of the FeCl 3 ·6H 2 O, CrCl 3 ·6H 2 O and KBH 4 powders. The characterizations show that the product is mainly composed of amorphous iron boron alloy nanoparticles. 57 Fe Mossbauer spectra at 84 and 295 K show that there are three kinds of Fe-containing components in the sample. There are the superparamagnetic relaxation in Mossbauer spectra and the continuous distribution of internal magnetic field in the iron boron alloy.

AC losses in multi-filamentary tapes depend on various parameters. Among them, the overall tape width and thickness are expected to have an important influence. In order to study this geometrical effect, five Bi-2223/Ag tapes with different aspect ratios from 5 to 26 have been prepared. AC losses have been measured at 77 K when a perpendicular AC magnetic field is applied. It has been found that at any frequencies the magnetic loss per cycle increases as the aspect ratio increases. For AC magnetic loss, with increasing frequency from 3 to 9000 Hz the losses as a function of frequency show a maximum if the field amplitude is much less than the full penetration field or increase continuously if the field amplitude is larger.

This paper presents a novel approach of modeling the delamination phenomenon experienced by laminated composite plate and shell structures by using a previously developed layerwise shell finite element in conjunction with some transformations. This layerwise element is formulated by stacking some single-layered shell elements through a transformation of displacements of the mid-surface of a layer to those on the mid-surface of the laminated composite shell structure. It can accurately model the overall displacements and interlaminar stresses of a laminated composite shell structures whose layers are perfectly (rigidly) bonded. The novelty of the present approach, however, lies in the fact that two different transformations are used so that interlaminar displacements as well as interlaminar stresses can be represented in the finite element model. The transformations allow for displacement mismatches across the normal direction of the layer interfaces (the normal mode of delamination) and between layers (the shear mode). As a result, the proposed methodology can be used to model the open and shear modes of delamination. A two-layered simply supported composite beam and a two-layered simply supported cross-ply square plate are then chosen for numerical studies. These examples demonstrate how the present approach can be applied to accurately model delamination phenomena such as shear slip and normal separation. The paper concludes with suggestions for future work.

The nickel ferrite ultrafine powders with different grain sizes (8, 12, 20, 40 and 80 nm) have been synthesized. Mossbauer spectra of Fe-57 nucleus in the samples composed of the nickel ferrite ultrafine powder before and after the high pressure treatments have been measured. The superparamagnetic relaxation is markedly suppressed by high pressure. The intensity of the sextets in Mossbauer spectra increases with increasing the grain size or pressure. The effect of high pressure on Mossbauer spectra of the samples may involve not only the physical changes, but also the chemical or structural ones in the ultrafine particles during the high pressure treatment, such as the formation of the interfacial region between the ultrafine particles and the rearrangements of the atoms in the surface layers of the ultrafine particles. (C) 2000 Elsevier Science S.A. All rights reserved.

La 1− x Ca x Cr 1− x Fe x O 3 ( x = 1/4, 1/3) are synthesized by wet chemical method and the crystal structure of the compounds belongs to orthorhombic system. Mossbauer spectra of 57 Fe nucleus show that all the iron ions in the compounds are trivalent and in high-spin state. A tight-bending method on the basis of EHMO approximation has been performed to calculate the average valence states of various ions in La 3/4 Ca 1/4 Cr 3/4 Fe 1/4 O 3 . The results indicate that the average valence state of chromium ion increases with doping calcium ion, but that of iron ion still is trivalent in the compound. Doping calcium and iron ions may have a certain effect on energy band structure and on conduction mechanism in lanthanum chromite.

Change in the quadrupole splitting of 151 Eu nucleus in the Mossbauer spectra of an EuBa 2 Cu 3 O 7− x thick film at 105 K has been observed when an AC electric current passes the thick film. It has been found that the quadrupole splitting of 151 Eu nucleus increases with increasing the frequency of the electric current passing the thick film and that the relationship between the quadrupole splitting of Eu nucleus in the superconducting thick film and temperature before the superconducting transition can also obey the formula presented by Heubes and Christiansen. This phenomenon may be attributed to the hysteresis loss of the alternating current passing the superconducting regions in the EuBa 2 Cu 3 O 7− x thick film.

Mossbauer spectra of Fe-57 in a thick film YBa2(Cu0.97Fe0.03)(3)O7-x irradiated by a large dose of gamma-rays from Co-60 have been measured. The variation of the relative intensities of some subspectra of Fe-57 in the. Mossbauer spectra of the thick film YBa2(Cu0.97Fe0.03)(3)O7-x after irradiation can be observed. This variation indicates that the change of the coordination environment around some Fe atoms in the lattice occurs due to irradiation. The relative intensity of subspectrum D1(Fe) at the Cu(1) site decreases and that of subspectrum D4(Fe) at the Cu(1) site increases. This may be because of the possible oxygen atom hopping between the coordination environments of D1(Fe) and D4(Fe) in the lattice caused by irradiation. The effect of irradiation on the coordination environment around the Fe atom at the Cu(2) site is not appreciable. (C) 1997 Elsevier Science B.V.

Finite elements that are capable of representing vibration behaviour of general plate and shell structures have been developed and presented in this paper. The formulations and derivation of the explicit stiffness matrices of the elements have already been proposed and obtained earlier by the authors. These three-node 18-d.o.f. flat triangular shell elements have proved to be accurate and reliable for general shell structures under static loads. In the present paper, explicit expressions for corresponding consistent mass matrices are derived. The shell elements are of the hybrid strain type and degenerate in nature. This degenerate nature allows for applications to thin as well as to moderately thick to thick shells and makes extension to non-linear analysis simple. The hybrid strain feature, however, provides continuity of displacements and strains. Efforts are also directed to address the issue of normal rotation. The presented elements are capable of reflecting true normal rotation as well as desirable membrane and bending behaviour. Computed results of several problems that were considered in the obstacle course of the static analysis are included to demonstrate the accuracy and capability of the elements.

Aspects and theories of nonlinear analysis of structures, with special emphasis on structures that are discretized by the finite element method, are discussed. The updated Lagrangian formulation and the incremental Hellinger-Reissner variational principle are adopted. The independently assumed fields employed are the incremental displacements and incremental strains. Accordingly, the incremental second Piola-Kirchhoff stress and the incremental Washizu strain are selected as the incremental stress and strain measures. Various schemes for the transformation of the second Piola-Kirchhoff stress to Cauchy stress are included. Two versions of linear and nonlinear element stiffness and mass matrices are considered. These are the director and simplified versions. Variable thickness of the shell is considered so as to account for the ‘thinning effect’ due to large strain. Material nonlinearity studied in this paper is of elasto-plastic type with isotropic strain hardening. Cases in which small elastic but large plastic strain condition applies are considered and the J2 flow theory of plasticity, in conjunction with Ilyushin's yield criterion, is employed. To simplify the derivation of (small displacement) stiffness matrix and to facilitate the derivation of explicit expressions for the element matrices, the non-layered approach has been applied.

In a companion paper [M. L. Liu and C. W. S. To, Comput. Struct. 54, 1031–1056 (1995)] theories and incremental formulation of nonlinear shell structures discretized by the finite element method are discussed. The updated Lagrangian formulation and the incremental Hellinger-Reissner variational principle are adopted. The independently assumed fields employed are the incremental displacements and incremental strains. Based on the theory and incremental formulation explicit element stiffness and mass matrices of three node flat triangular shell finite elements are derived. In the present paper the derived element matrices are applied to nine examples. The latter include static and dynamic response analysis of shell structures with geometrical, material, and geometrical and material nonlinearities. The formulation adopted and element matrices derived are found to be accurate, flexible and applicable to various types of shell structures with geometrical and material nonlinearities.

A technique that incorporates the stochastic central difference method and time co-ordinate transformation is presented and applied to the determination of time-dependent variances and covariances of responses of beam and plate structures discretized by the finite element method. A formula has been established for the evaluation of the dimensionless time step size used in the response computation. This dimensionless step size is related to the dimensionless fundamental natural frequency of the discretized system. Results obtained by the technique are compared with solutions calculated by the exact expressions presented earlier by the first author. It is concluded that the technique gives very accurate results and is a very effective alternative to existing techniques available in the literature.

Three adaptive time schemes are incorporated into the stochastic central difference method with time co-ordinate transformation for the determination of the covariances of responses of multi-degree-of-freedom non-linear systems. The results of a Duffing's oscillator and a two-degree-of-freedom system with asymmetric non-linear stiffness indicate that the proposed procedures are very accurate and efficient to apply compared with digital simulation. They are free from computational instability. A relation for the computation of the time step size required in the implementation of the procedures has also been presented.

In this paper we present recursive expressions for time dependent means and mean square responses of a multi-degree-of-freedom (MDOF) system with non-symmetric non-linearities in its stiffness terms. Based on the stochastic central difference-cum-statistical linearization (SCD-SL) technique, four recursive schemes for this system are derived. These schemes are implemented in a digital computer program written in Fortran 77. The results of both the stationary and time dependent means and mean square responses obtained by using the computer program are compared with those employing the Monte Carlo simulation (MCS) technique. It is concluded that (a) the recursive expression schemes are easy to be implemented in a digital computer program, (b) the computed stationary and time dependent means and mean square responses are accurate, and (c) the schemes are far more economical to employ than the MCS technique.

Mossbauer spectroscopy has been used to investigate the thermal decomposition of the bioinorganic complex of europium and l -glutamine. The Mossbauer parameters can demonstrate that the water molecules in the complex and the chlorine anion in the hydrogen chloride molecule, dissociated from the complex below 200°C, are not linked directly to the europium atom. The thermal decomposition process of the complex is discussed and a possible coordination model for the europium l -glutamine complex is also proposed on the basis of the thermogravimetric and derivative thermogravimetric curves, and from some evidence obtained from the Mossbauer effects of some decomposition products of the complex.

A 4.5GHz circularly polarized YBCO microstrip antenna was designed and fabricated. Measurements showed that at 77K the superconducting antenna had about 3dB gain improvement over the comparable silver antenna, in agreement with the calculated results using the modified Green function method.

Laser-induced voltage pulses of several tens volts have been observed in YBa 2 Cu 3 O 7−δ films with a tilted orientation at room temperature. In this paper, we present the experiment results concerning the dependence of the response time on the film thickness, the tilt angles and the way of irradiation.

The epitaxial Tl 2 Ba 2 CaCu 2 O 8 films were prepared by magnetic sputtering on (100) SrTiO 3 substrates but with a tilt angle ( α =0°,10°,20°). Through analysis of SEM and X-ray diffraction, we studied the surface topography and structure of the films: the smaller the tilt angle of the substrate, the smoother the film surface and the better the film texture along C-axis. Voltage pulses can be observed on TlBaCaCuO films with a tilt orientation(10° and 20°). The amplitude of signals is related to the structure of the films.

A simple structural model is developed for glasses of the lithium borosilicate (Li 2 OB 2 O 3 SiO 2 ) system. The model involves three assumptions concerning distributions of the lithium ions in the borate and silicate networks. Several parameters appearing in the model reveal the composition at which particular boron-oxygen units are initially formed in the glasses. The model also yields predictions of the fractions of the various boron-oxygen units (e.g. BO 4 , BO 3 −1 ) that are in acceptable agreement with experiment.