Granular transport in a horizontally vibrated sawtooth channel

We present a new mode of transport of spherical particles in a horizontally vibrated channel with sawtooth shaped side walls. The underlying driving mechanism is based on an interplay of directional energy injection transformed by the sidewall collisions and density dependent interparticle collisions. Experiments and matching numerics show that the average particle velocity reaches a maximum at 60% of the maximal filling density. Introducing a spatial phase shift between the channel boundaries increases the transport velocity by an order of magnitude.Comment: 5 pages, 8 figure

Yielding and Strain Stiffening in Entangled Assemblies of Frictional Granular Chains

Packings of macroscopic granular chains capture some of the essential aspects of molecular polymer systems and have been suggested as a paradigm to understand the physics on a molecular scale. However, here we demonstrate that the interparticle friction $\mu$ in granular chain packings, which has no counterpart in polymer systems, leads to a nontrivial yielding and rheological response. Based on discrete element simulations we study the nonlinear rheology of random packings of granular chains under large amplitude oscillatory shear. We find that the maximum stress and the penetration depth of the shear deformation into the material bulk are nonmonotonic functions of friction with extrema at intermediate values of $\mu$. We also show that the regularly repeated gaps between the adjacent grains, which are special to commercial granular chains, broaden the shear zone and enhance the entanglements in the system by promoting the interlocking events between chains. These topological constraints can significantly increase the degree of strain stiffening. Our findings highlight the differences between the physics of granular chain packings and molecular polymer systems.Comment: 7 pages, 5 figure

Compaction of Quasi One-Dimensional Elastoplastic Materials

Insight in the crumpling or compaction of one-dimensional objects is of great importance for understanding biopolymer packaging and designing innovative technological devices. By compacting various types of wires in rigid confinements and characterizing the morphology of the resulting crumpled structures, here we report how friction, plasticity, and torsion enhance disorder, leading to a transition from coiled to folded morphologies. In the latter case, where folding dominates the crumpling process, we find that reducing the relative wire thickness counter-intuitively causes the maximum packing density to decrease. The segment-size distribution gradually becomes more asymmetric during compaction, reflecting an increase of spatial correlations. We introduce a self-avoiding random walk model and verify that the cumulative injected wire length follows a universal dependence on segment size, allowing for the prediction of the efficiency of compaction as a function of material properties, container size, and injection force.Comment: 7 pages, 6 figure

An Interleaved High Step-Up DC-DC Converter with Coupled Inductor and Built-In Transformer for Renewable Energy Applications

This paper introduces an interleaved high step-up DC-DC converter with high voltage gain, low voltage stresses on the switches, low current stresses on the components, and continuous input current with low ripple, all of which are beneficial for the renewable energy (RE) applications. The proposed converter is based on the integration of three voltage-boosting (VB) methods: coupled inductor (CI), built-in transformer (BIT), and switched-capacitor (SC) cells. The energies of the leakage inductances of the CIs and BIT are absorbed and recirculated to the output side, which further extends the voltage gain. In addition, the current-falling rates of the diodes are controlled by the leakage inductances, which leads to the reduced reverse-recovery losses of the diodes. The operating stages, steady-state analysis, and a comparison with similar existing topologies are presented in this paper. Furthermore, the performance of the proposed converter is verified through the experimental results of a 200-W prototype with an output voltage of 400 V and a voltage gain of 30

An Interleaved High Step-Up DC-DC Converter with Built-In Transformer-Based Voltage Multiplier for DC Microgrid Applications

This paper proposes a high step-up DC-DC converter with a built-in transformer (BIT)-based voltage multiplier (VM) that is suitable for integrating low-voltage renewable energy sources into a DC microgrid. A three-winding BIT is combined with the switched-capacitor (SC) cells to extend the voltage gain and reduce the voltage stress on the switches. The current-falling rates of the diodes are controlled by the leakage inductances of the BIT, alleviating the reverse-recovery problem of the diodes. The operating modes and steady-state analysis are presented. Additionally, the validity of the proposed converter is confirmed by the simulation and experimental results of a 400 W converter with an input voltage of 20 V and output voltage of 400 V. Moreover, a comparison study is presented to verify the superiority of the proposed converter over the closest existing topologies in the literature

A High Step-Up Dc-Dc Converter using a Three Winding Coupled Inductor for Photovoltaic to Grid Applications

A dual-switch high step-up DC-DC converter topology is proposed in this paper. The proposed topology uses two power switches, a three-winding coupled inductor (TWCI), and voltage multiplier cells to provide a high voltage gain. Furthermore, the voltage stresses on power semiconductor switches are low, resulting in lower switching and conduction losses. Moreover, the common electrical ground is preserved in this topology, making it a suitable candidate for photovoltaic (PV) to grid systems. The operating modes and steady state analysis of the proposed converter are presented, and a comparative study is carried out to demonstrate advantages of the proposed topology over the existing topologies. Finally, the simulation results of the proposed topology are presented using PLECS software along with the experimental results for a 200 W, 30 V to 400 V laboratory setup

{N,N′-Bis[(E)-3-phenyl­prop-2-en-1-yl­idene]propane-1,3-diamine-κ2 N,N′]dichloridocobalt(II)

The CoII atom in the title monomeric Schiff base complex, [CoCl2(C21H22N2)], is bonded to two Cl atoms and to two N atoms of the Schiff base ligand N,N′-bis­[(E)-3-phenyl­prop-2-en-1-yl­idene]propane-1,3-diamine in a distorted tetra­hedral geometry. The mol­ecule has an idealised mirror symmetry, but is not located on a crystallographic mirror plane