Cation vacancy related crystal structure and bandgap and their effects on the thermoelectric performance of Cu-ternary systems Cu3+δIn5Te9 (δ = 0–0.175)

The fundamental impact of the crystal distortion (CD) on the lattice part (κL) has been revealed in the Cu3In5Te9-based ternary system.

Impact of the iron substitution on the thermoelectric properties of Co 1− x Fe x S 2 ( x ≤ 0.30)

The strong interplay between magnetism and transport can tune the thermoelectric properties in chalcogenides and oxides. In the case of ferromagnetic CoS 2 pyrite, it was previously shown that the power factor is large at room temperature, reaching 1 mW m −1 K −2 and abruptly increases for temperatures below the Curie transition ( T C ), an increase potentially due to a magnonic effect on the Seebeck ( S ) coefficient. The too large thermal conductivity approximately equal to 10.5 W m −1 K −1 at room temperature prevents this pyrite from being a good thermoelectric material. In this work, samples belonging to the Co 1− x Fe x S 2 pyrite family ( x = 0, 0.15 and 0.30) have thus been investigated in order to modify the thermal properties by the introduction of disorder on the Co site. We show here that the thermal conductivity can indeed be reduced by such a substitution, but that this substitution predominantly induces a reduction of the electronic part of the thermal conductivity and not of the lattice part. Interestingly, the magnonic contribution to S below T C disappears as x increases, while at high T , S tends to a very similar value (close to −42 µV K −1 ) for all the samples investigated. This article is part of a discussion meeting issue ‘Energy materials for a low carbon future’.

Investigation of the Free Vibrations of Composite Anisogrid Lattice Conical Shells Formed by Geodesically Spiral and Circumferential Ribs

This paper focuses on the dynamic behavior of composite anisogrid lattice conical shells. Lattice composite conical shell consists of composite helical and circumferential ribs and thin outer skin. The free vibration analysis of anisogrid composite lattice conical shell is presented. A smeared method is employed to calculate the variable coefficients of stiffness of conical shell and more close to the realistic applications. The lattice part of conical shell is modeled as a beam, so in addition to the axial loads, ribs endure shear loads and bending moments. The first-order shear deformation shell theory is used to account for the effects of transverse shear deformations and rotary inertia. The current results are verified with 3D finite element model of conical shell by ANSYS Software and those reported in the literature. Some special cases as influences of geometric parameters of lattice part of shell, effects of boundary conditions and circumferential wave number on natural frequencies of the shell are discussed. It was concluded that employment of the smear method could be recommended for determining the coefficients of stiffness of the composite lattice conical shells with outer skin. Also increasing the vertex angle of cone increases the natural frequencies of conical shell.

AN IMPLEMENTATION OF LATTICE FILTERS USING FOUR OPERANDS REAL MULTIPLY ACCUMULATION

Four operands Real Multiply Accumulation (4op-RMA) is a method to implement transversal circuits, direct form circuits and 2D type circuits with real coefficients by using a complex multiplier. Digital Signal Processors (DSPs) with 4op-RMA implement these circuits twice as fast as the conventional ones. Besides, we can simplify the programs on such DSPs. However 4op-RMA have not been applied to the lattice circuits yet because of their circuit structures. In this paper, we propose an implementation method for the lattice circuits by using 4op-RMA. The lattice part can be calculated by a 4op-RMA operation, which corresponds to a complex multiplication.