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The switching behaviour of dihydroazulene/vinylheptafulvene molecule with different anchoring groups sandwiched between two zigzag-edged graphene nanoribbons (ZGNRs) electrodes is investigated by applying nonequilibrium Green's function formalism combined with first-principles density functional theory. The calculated results show that the anchoring groups play a significant role in determining the electronic transport properties and switching behaviour of the molecular junctions. A higher current switching ratio without any oscillation can be obtained for the molecular junctions with carbon atom anchoring group, which suggests that this system has a broader application in future logic and memory devices.

Based on the nonequilibrium Green's function method and density functional theory calculations, we investigate the electronic transport properties of a single chiroptical molecular switch with two zigzag graphene nanoribbon electrodes. The molecule undergoing the switch can exhibit different chirality namely cis -isomer and trans -isomer by ultraviolet or visible irradiation. Theoretical results clearly reveal that these two isomers exhibit very different current – voltage characteristics, which can realize the switching behaviors when the molecule converts between cis -isomer and trans -isomer. Furthermore, the negative differential resistance behaviors also can be observed in these two isomers, suggesting potential applications of this type of junctions in future design of functional molecular devices.

Medium-sized high-voltage motor’s starter temperature rising is difficult to accurately calculate. In this paper, the heating and cooling process at the start of the motor windings are analyzed, from the perspective of practical engineering, according to the actual structure of the motor, the motor drag establish a network model and dynamic thermal network diagrams, calculating the electrical heating and cooling conditions. This paper took consideration of the influence to the motor heating from current and impedance changes in the process of starting. Taking the times as the step size and basing on the raw heat and heat capacity of each period to calculate the motor temperature rise of the motor windings. For example the motor of YJKK500-4, 2500kW motor, calculating the motor winding temperature raise, the calculation which achieved with the experimental results, the calculation method has the engineering practicality.

The electronic transport properties of oligo p-phenylenevinylene (OPV) molecule sandwiched with symmetrical or asymmetric tailoring graphene nanoribbons (GNRs) electrodes are investigated by nonequilibrium Green’s function in combination with density functional theory. The results show that different tailored GNRs electrodes can modulate the current–voltage characteristic of molecular devices. The rectifying behavior can be observed with respect to electrodes, and the maximum rectification ratio can reach to 14.2 in the asymmetric AC–ZZ GNRs and ZZ–AC–ZZ GNRs electrodes system. In addition, the obvious negative differential resistance can be observed in the symmetrical AC-ZZ GNRs system.

By applying first-principles method based on density functional theory combined with nonequilibrium Green’s function, we investigate the effect of torsion angle on the electronic transport properties in dipyrimidinyl–diphenyl co-oligomer molecular device with tailoring graphene nanoribbon electrodes. The results show that the torsion angle plays an important role on the electronic transport properties of the molecular device. When the torsion angle rotates from 0[Formula: see text] to 90[Formula: see text], the molecular devices exhibit very different current–voltage characteristics which can realize the on and off states of the molecular switch.

Based on the nonequilibrium Green function method and density functional theory calculations, we theoretically investigate the effect of chirality on the electronic transport properties of thioxanthene-based molecular switch. The molecule comprises the switch which can exhibit different chiralities, that is, cis-form and trans-form by ultraviolet or visible irradiation. The results clearly reveal that the switching behaviors can be realized when the molecule converts between cis-form and trans-form. Furthermore, the on-off ratio can be modulated by the chirality of the carbon nanotube electrodes. The maximum on-off ratio can reach 109 at 0.4 V for the armchair junction, suggesting potential applications of this type of junctions in future design of functional molecular devices.