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Hollow Fe 3 O 4 nanospheres with the diameter of 450 nm and the wall thickness of 80 nm are prepared using the Ostwald ripening process. The composites filled with the hollow nanospheres of 60 wt% have good high-frequency and absorption properties. In RL – f curves, two absorption frequencies are found, which have their origins in quarter-wavelength resonator and magnetic resonance, respectively. Based on the quarter-wavelength resonator model, the calculated f A 1 and RL A 1 are in a good agreement with the observed values. Due to the overlap of the two absorptions, the frequency band is expanded. The composite with light weight of the density of 2.71 g/cm 3 has bandwidth W P of 65% with return loss RL ≤ − 10 dB at thickness of 0.3 cm for EM absorption or attenuation applications. [ABSTRACT FROM AUTHOR]

Abstract: One-dimensional measurement along the Line-Of-Sight (LOS) direction has greatly limited the capability of InSAR technique in the investigation of surface displacements and their dynamics. In recent years, great efforts have been made to resolve complete three-dimensional (3-D) displacements from InSAR measurements. This contribution is intended to provide a systematic review of the progress achieved in this field. Based on an analysis of the InSAR LOS measurements, we first cover two commonly used techniques, i.e., Offset-Tracking and multi-aperture InSAR (MAI), with which the surface displacement in the azimuth direction can be measured together with the LOS displacement. Several methods for mapping 3-D displacements using InSAR measurements are subsequently presented and categorized into three groups: (i) combination of multi-pass LOS and azimuth measurements; (ii) integration of InSAR and GPS data; and (iii) prior information assisted approaches. The strengths and weaknesses of each method are analyzed to show the applicability of each method to specific 3-D displacement mapping cases, in hope to provide a useful guidance in choosing a suitable approach accordingly. Finally, suggestions for resolving the challenging issues and outlook of future research are given. [Copyright &y& Elsevier]

Plate-like W-type barium ferrites (BaCoZnFe16O27) were prepared by using a combined method of molten salt and a sol–gel process. Pure plate-like W-type barium ferrite with large size about 25 μm and high aspect ratio (diameter/thickness) of ∼35 was obtained at a sintering temperature of 1200 °C. Morphology, phase evolution and static properties of the samples sintered at different temperatures (800–1200 °C) and dynamic magnetic properties of their composites with silicon resin were investigated by using SEM, XRD, VSM and VNA. It was found that the saturation magnetization M s increased with increasing sintering temperature, whereas the coercivity H c decreased. Silicon resin composites filled with 45 vol% of the plate-like BaCoZnFe16O27 particles sintered at 1200 °C exhibited promising microwave attenuation properties. [ABSTRACT FROM AUTHOR]

Abstract: Fe/SiO2 particles with core/shell structure were prepared by coating silica on the surface of a commercial spherical carbonyl iron via the hydrolysis process of tetraethyl orthosilicate (TEOS). The electromagnetic performance of commercial carbonyl iron and as-prepared Fe/SiO2 particles was studied theoretically and experimentally. As predicted by the theoretical calculation based on the Bruggeman formula and the Landau–Lifshitz–Gilbert (LLG) theory, the insulating surface layer of silica was effective to reduce the permittivity parameters of pure carbonyl iron. The measured results showed good agreement with the theoretical prediction. Although there was a little decrease in the permeability of the Fe/SiO2 core/shell particles, a better impedance match especially at higher frequency range was obtained when used as a microwave absorber. The reflection loss (RL) curves show that the lowest reflection loss of Fe/Epoxy composite (−20.5GHz) was obtained corresponding to the frequency of 8.5GHz when the thickness of the absorber was 3mm. A different trend was observed in Fe/SiO2/Epoxy composite. The reflection loss value got lower by decreasing the thickness of absorbers. At the thickness of 2.2mm, a relative low reflection loss (−17GHz) corresponding to the frequency of 13.6GHz was obtained. Compared with the Fe/Epoxy composite, the improvement on shifting the reflection loss peak to higher frequency and on reducing the optimal thickness of absorbers was made by Fe/SiO2/Epoxy composite. [Copyright &y& Elsevier]

Abstract: Sendust flakes (with 9.59% Si, 5.88% Al and balanced Fe) were coated with NiCuZn ferrite nanoparticles by using a simple sol–gel approach. Both the coated and uncoated flakes were characterized by using scanning electron microscopy, X-ray diffraction and vibrating sample magnetometer. Composites made from the Sendust flakes with the in-plane alignment were fabricated via a vacuum infiltration method. Microwave measurement results indicated that permittivity of the composite made of the coated Sendust flakes was remarkably reduced, with a slight decrease in permeability over 0.1–8.55GHz. Consequently, the sample with a thickness of 6mm showed reflection loss exceeding −20dB at 1.4GHz, while reflection loss of the composite derived from the uncoated Sendust flakes could not reach −10dB at the same sample thickness. Therefore, the Sendust flakes coated with NiCuZn ferrite nanoparticles could be promising candidates to develop microwave attenuation materials. [Copyright &y& Elsevier]

Abstract: High-frequency magnetic properties at K and Ka bands (18–40GHz) have been studied for M-type barium ferrite BaMn x Ti x Fe12−2x O19 (x=0.4–1.0) composites. The results show that complex permeability of the composites has a resonancelike-type dispersion. Although () is rather small (about 0.2), achieves 0.53–0.78, due to small effective damping coefficient. The composites also exhibit relatively high resonance frequencies f R covering 20–33GHz, which are proportional to anisotropy fields H a of the barium ferrites. These properties will be beneficial to the design of electromagnetic composites at a desired working frequency. [Copyright &y& Elsevier]

Abstract: Free-standing thick films of spinel ferrite, Ni0.89−x Cu0.11Zn x Fe2O4 with x=0.55 and 0.60, were prepared as fillers to fabricate electromagnetic composites. Compared to those made with conventional spherical fillers, the composites made with thick film fillers showed enhanced static permeability (μ′0) and maximum imaginary permeability (μ″max). At the same time, complex permittivity (ε′ and ε″) were almost unchanged. A relative bandwidth W R of 7–8 was achieved, which is about 75% of the theoretical maximum relative bandwidth. These composites are potential candidates as electromagnetic attenuation materials with ultrabroad absorption bandwidth in L and S bands. [Copyright &y& Elsevier]

Abstract: The effects of Ti substitution on magnetic properties, including saturation magnetization , intrinsic coercivity , Curie temperature and spin reorientation (SR) transition, have been studied for Z-type hexaferrites with . The SR transition from c-plane to c-axis anisotropy is determined, based on the temperature dependence of magnetization at a small applied magnetic field of 100Oe. The results show that, with Ti substitution, increases to the maximum and then decreases, decreases, while SR transition temperature is elevated. [Copyright &y& Elsevier]

Abstract: CoCu nanowires were fabricated in anodic alumina templates by a simple metal displacement deposition method and the as-deposited samples were subsequently annealed at 400°C in vacuum. The CoCu nanowires are 80nm in diameter and 50μm in length. The aspect ratio (ratio of length to diameter) is larger than 600, which results in distinctive magnetic anisotropy. Enhanced coercivity (about 2245Oe) and large squareness of 92% have been observed in the annealed samples. [Copyright &y& Elsevier]

Abstract: A new functional model for determining the minimum and maximum detectable deformation gradients of interferometric synthetic aperture radar (InSAR) is developed. The model incorporates both the interferometric coherence and the look number, representing an extension to the existing models that consider only the interferometric coherence. Experimental results with Envisat ASAR data show that the new model performs well for interferograms with different look numbers and interferometric coherences. The model can serve as an important tool in determining whether InSAR technology can be used effectively to monitor a particular ground deformation. In addition, the model can also be used to determine the optimum look number for multi-looking operations to result in the best deformation monitoring results. [Copyright &y& Elsevier]

As a structural object of Petri nets, siphons play a key role in the development of deadlock prevention policies for resource allocation systems. The siphon solution in Petri nets has been extensively investigated in the literature. Since the number of siphons in a net grows quickly and in the worst case grows exponentially with respect to the size of a net, their computation is expensive. This paper aims to find the strict minimal number of siphons in a class of Petri nets, called extended systems of linear simple sequential process with resources, which can model flexible manufacturing systems where there exist no flexible processing routings except for the idle state and each operation state may require more than one sort of resources. First, a relationship between structural properties and strict minimal siphons in the class of Petri net is verified. Second, we define the resource digraph of the class net. Finally, based on the obtained results, a method to find the set of strict minimal siphons is proposed. A running example is used to demonstrate the proposed methods. [ABSTRACT FROM PUBLISHER]

Abstract: Ni0.23Cu0.11Zn0.66Fe2O4 nanowire arrays were fabricated by a simple ethanol–nitrate method using anodic aluminum oxide (AAO) templates. XRD result indicated that the nanowires are of cubic spinel structure. SEM and VSM were used to characterize morphology and magnetic anisotropy properties of the nanowire arrays, respectively. It is believed that this method should be applicable to other multi-component oxide nanowires. [Copyright &y& Elsevier]

Measurement of the flame temperature in a micro combustor is essentially difficult due to the size constraint. A one-dimensional (1D) flame model coupled with the heat conduction in the solid wall is employed to analyze the heat transfer occurring in a cylindrical micro combustor. The flame temperature is given explicitly by taking into account the effects of the heat loss (from the flame to the wall) in the reaction zone and heat recirculation through the solid wall. With the data obtained from the simulation results of the 1D adiabatic freely propagating CH4-air laminar flames, the flame temperature in a cylindrical micro combustor can be solved iteratively. In order to validate the 1D model, the two-dimensional (2D) numerical simulations of premixed combustion of the CH4-air mixtures are carried out in a 0.5 mm radius cylindrical micro combustor. The comparisons of the flame temperature and heat recirculation between the 1D model and 2D numerical simulation indicate that despite the simplifications and assumptions made in the present study, the 1D theoretical model is able to predict the flame temperature to a reasonable accuracy. [ABSTRACT FROM AUTHOR]

Abstract: Free-standing Ni0.23Cu0.11Zn0.66Fe2O4 thick films have been prepared using a modified tape-casting method from a viscous paint. The surface morphology, saturation magnetization (M s), coercivity (Hc ) and complex permeability of the thick films were studied. It is demonstrated that the thick films have relatively larger complex permeability and higher resonance frequency as compared to their bulk material counterparts. [Copyright &y& Elsevier]

Abstract: High-frequency magnetic properties and attenuation characteristics for barium-ferrite/epoxy composites have been studied. The methods for increasing μ′ and μ″ and controlling f R, including ion substitution, doping of small amount of oxides, effect of damping, as well as the modification of particle sizes and shapes, are introduced. The results show that the composites are potential candidates for use as electromagnetic (EM) attenuation materials with low reflectivity and broad bandwidth at 2–18GHz. [Copyright &y& Elsevier]

Abstract: Phase noise in a radar interferogram is directly related to interferometric coherence and the look number of the interferogram. Therefore an optimal radar interferogram filter should incorporate information on both interferometric coherence and look number. We present a modification to the commonly used Goldstein filter by suggesting an improved determination of the filtering parameter. Experimental results with both simulated and real data sets show that the new filter offers much better results when used to filter radar interferograms. [Copyright &y& Elsevier]

Abstract: The effects of concentration of Bi2O3 and sintering temperature on DC resistivity, complex relative permittivity and permeability of MgFe1.98O4 ferrite ceramics were studied. The objective of the study was to develop magneto-dielectric materials, with almost equal values of permeability and permittivity, as well as low magnetic and dielectric loss tangent, for the design of antennas with reduced physical dimensions. It was found that the poor densification and slow grain growth rate of MgFe1.98O4 can be greatly improved by the addition of Bi2O3, because liquid phase sintering was facilitated by the formation of a liquid phase layer due to the low melting point of Bi2O3. It was found that 3% Bi2O3 can result in fully sintered MgFe1.98O4 ceramics. The DC resistivities of the MgFe1.98O4 ceramics were increased as a result of the addition of Bi2O3, except for 0.5%. The exceptionally low resistivities of the 0.5% samples were explained by a ‘cleaning’ effect of the small amount of liquid phase at the samples’ grain boundaries. The electrical and magnetic properties of the MgFe1.98O4 ceramics exhibited a strong dependence on the concentration of Bi2O3. The 0.5% samples were found to have the highest dielectric loss tangents, which can be understood similarly to the DC resistivity results. The 2–3% Bi2O3 is required to attain low dielectric loss MgFe1.98O4 ceramics for antenna application. Low concentration of Bi2O3 increased the static permeability of the MgFe1.98O4 ceramics owing to the improved densification and grain growth, while too high a concentration led to decreased permeability owing to the incorporation of the non-magnetic component (Bi2O3) and retarded grain growth. However, the addition of Bi2O3 alone is not able to produce magneto-dielectric materials based on MgFe1.98O4 ceramics, and further work is necessary to modify the permeability using cobalt (Co). [Copyright &y& Elsevier]