Research of Sets of Solid Oxide Fuel Cells in Packed Version

The stressed state of fuel cells in a package is considered. It was found that for αi=1.2×10−5k−1, the rational geometric characteristic for a planar SOFC in a batch design is γi=6×10−2. It is concluded that if the relative thickness of the edge element of the SOFC stack is of planar design γi>6×10−2, then the resulting deformation complication will be characterized by the loss of stability of the structure. Otherwise, i. e. at γi<6×10−2, stacked SOFC elements can lose stability until plasticity appears in their materials. Consequently, only at γi=6×10−2, the use of the potentials of structures can be achieved both in terms of the stability of its elements and the strength of their materials.

A Novel Shape Compact Antenna for Ultrawideband Applications

Nowadays, more attention has been given into ultrawideband by dint of its extraordinary features over narrowband communication systems. This study presents a novel compact with tilted square frames shape antenna with partial ground plane. The proposed antenna is printed on commercially available Fr4 substrate with relative thickness of 1.6 mm. The antenna has compact dimensions of 14 × 18 mm2 with bandwidth ranging from 3.3 to 11.5 GHz. The peak gain obtained is 1.4 dBi with omnidirectional radiation characteristics throughout the entire bandwidth. The proposed antenna is fabricated, and the developed prototype measured results, which well agree with simulated results. With the performance parameters obtained and the well agreed measured results, the proposed antenna is well suitable for Wi-Fi, ISM, and UWB applications.

Environmental and diagenetic controls on the morphology and calcification of the Ediacaran metazoan Cloudina

Cloudina is a globally distributed Ediacaran metazoan, with a tubular, funnel-in-funnel form built of thin laminae (ca. 1–10 μm). To what degree local environmental controlled morphology, and whether early diagenesis controlled the degree of calcification of Cloudina, is debated. Here we test these hypotheses by considering assemblages from four, coeval localities from the Upper Omkyk Member, Nama Group, Namibia, from inner ramp to mid-ramp reef across the Zaris Subbasin. We show that sinuosity of the Cloudina tube is variable between sites, as is the relative thickness of the tube wall, suggesting these features were environmentally controlled. Walls are thickest in high-energy reef settings, and thinnest in the low-energy, inner ramp. While local diagenesis controls preservation, all diagenetic expressions are consistent with the presence of weakly calcified, organic-rich laminae, and lamina thicknesses are broadly constant. Finally, internal ‘cements’ within Cloudina are found in all sites, and pre-date skeletal breakage, transport, as well as syn-sedimentary botryoidal cement precipitation. Best preservation shows these to be formed by fine, pseudomorphed aragonitic acicular crystals. Sr concentrations and Mg/Ca show no statistically significant differences between internal Cloudina cements and botryoidal cements, but we infer all internal cements to have precipitated when Cloudina was still in-situ and added considerable mechanical strength, but may have formed post-mortem or in abandoned parts of the skeleton.

INFLUENCE OF THE PARAMETERS OF THE WAVE PROFILE OF THE JOINT BOUNDARY OF TITANIUM-ALUMINUM COMPOSITE LAYERS ON STRESS BEHAVIOR

Simulation by the finite element of tensile deformation of the titanium-aluminum composite D20 - AD1 - VT6S was carried out. The relative thickness of the soft layer AD1 was constant, and the parameters of the wave profile of the welded joint varied. An increase in the ratio of the amplitude to the step of the wave up to 0.5 leads to an increase in effort by 4-5%. It was compared with the force in a specimen with a flat boundary at comparable stretches. Plastic deformation is localized mainly near free surfaces.

SIMULATION OF THE BEHAVIOR OF TITANIUM-ALUMINUM COMPOSITE WITH WAVE PROFILE OF WELDED JOINT

The finite element simulation of tensile deformation of titanium-aluminum composite D20 - AD1 - VT6S was carried out. The composite had a wave profile of the welded joint at the boundaries D20 - AD1 and AD1 -VT6S. The thickness of the AD1 interlayer was varied in the simulation from 0.25 to 4 mm. The relative thickness of the interlayer corresponding to the onset of active deformation of the aluminum alloy has been determined.

Coupled vibrations of viscoelastic three-layer composite plates. 2. Numerical experiments

Results of numerical studies of the influence of reinforcement orientation of hard layers and the relative thickness of the soft layer of an isotropic viscoelastic polymer on the values of natural frequencies and coefficients of mechanical losses are discussed. In a symmetrical three-layer plate, a bending-torsion interaction arises, generating mutual transformations of the eigenmodes of the coupled vibration modes, if at least one of its own forms in plate directions is characterized by an even number quarters of a wave, and another proper form - an odd number of quarters the waves. In an unsymmetrical asymmetric three-layer plate, bending-bending interaction arises, generating mutual transformations eigenmodes of coupled vibration modes in two mutually orthogonal planes if in the main directions of the plate both of their own forms characterized by either an even or an odd number of quarters of a wave. It was found that each mode of natural vibrations of three-layer plates corresponds to the effective relative thickness of the soft isotropic layer viscoelastic polymer.

Leading edge redesign of dual-peak type variable inlet guide vane and its effect on aerodynamic performance

Recently, a new type airfoil for variable inlet guide vane (VIGV), featuring “dual-peak” surface velocity pattern at high incidence, is proposed and shows wide low-loss operation range. To further improve its performance, this paper researches the influence of leading edge (LE) thickness and shape on the loss level and surface velocity features of the “dual-peak” type airfoil. Firstly, a polynomial-based continuous-curvature leading edge design method was briefly introduced and used in the LE redesign of sample airfoils. Then, steady simulations based on Reynolds-Averaged Navier-Stokes method (RANS), carried out by commercial software CFX after grid independent study, were used to determine the aerodynamic performance, surface velocity distribution and boundary-layer behaviors of all research airfoils. Simulation results indicate that there exists an optimized range of LE relative thickness that can achieve lower airfoil loss level at high incidence condition. For Case 1 ([Formula: see text]) and Case 2 ([Formula: see text]), the optimized LE relative thickness range is [Formula: see text] and [Formula: see text]. The LE shape optimization can further reduce the maximum incidence condition loss coefficient with proportion up to 18% for airfoils with optimal LE thickness. Analysis of flow mechanism indicates that the optimized LE thickness and shape can reduce the suction spike height and subsequent adverse pressure gradient, therefore, decrease the LE separation scale and result in a lower loss coefficient. As an application, a dual peak VIGV with circular LE, presented in previous paper as the optimized VIGV, is redesigned in the LE portion according to the research findings and achieved 0.6 percent improvement in passage-averaged total pressure recovery coefficient [Formula: see text] at extreme high stagger angle point and the low-loss operation range extends with about 5°, which confirms the effectiveness of the research findings in three-dimensional environment.