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ABSTRACTS

Electric Field-Controlled Crystallizing CaCO3 Nanostructures from Solution

The role of electric field is investigated in determining the structure, morphology, and

crystallographic characteristics of CaCO3 nanostructures crystallized from solution. It is found that

the lattice structure and crystalline morphology of CaCO3 can be tailed by the electric field applied

to the solution during its crystallization. The calcite structure with cubic-like morphology can be

obtained generally without electric field, and the vaterite structure with the morphology of

nanorod is formed under the high electric field. The vaterite nanorods can be piled up to the

petaliform layers. Both the nanorod and the petaliform layer can have mesocrystal structures

which are piled up by much fine units of the rods with the size of several nanometers. Beautiful

rose-like nanoflowers can be self-arranged by the petaliform layers. These structures can have

potential application as carrier for medicine to involve into metabolism of living cell. © 2016, Qi et

al.

Bi-directional series-parallel elastic actuator and overlap of the actuation layers

Several robotics applications require high torque-to-weight ratio and energy efficient actuators.

Progress in that direction was made by introducing compliant elements into the actuation. A large

variety of actuators were developed such as series elastic actuators (SEAs), variable stiffness

actuators and parallel elastic actuators (PEAs). SEAs can reduce the peak power while PEAs can

reduce the torque requirement on the motor. Nonetheless, these actuators still cannot meet

performances close to humans. To combine both advantages, the series parallel elastic actuator

(SPEA) was developed. The principle is inspired from biological muscles. Muscles are composed of

motor units, placed in parallel, which are variably recruited as the required effort increases. This

biological principle is exploited in the SPEA, where springs (layers), placed in parallel, can be

recruited one by one. This recruitment is performed by an intermittent mechanism. This paper

presents the development of a SPEA using the MACCEPA principle with a self-closing mechanism.

This actuator can deliver a bi-directional output torque, variable stiffness and reduced friction. The

load on the motor can also be reduced, leading to a lower power consumption. The variable

recruitment of the parallel springs can also be tuned in order to further decrease the consumption

of the actuator for a given task. First, an explanation of the concept and a brief description of the

prior work done will be given. Next, the design and the model of one of the layers will be

presented. The working principle of the full actuator will then be given. At the end of this paper,

experiments showing the electric consumption of the actuator will display the advantage of the

SPEA over an equivalent stiff actuator. © 2016 IOP Publishing Ltd.

Study and experiment on non-contact voltage sensor suitable for three-phase

transmission line

A voltage transformer, as voltage signal detection equipment, plays an important role in a power

system. Presently, more and more electric power systems are adopting potential transformer and

capacitance voltage transformers. Transformers are often large in volume and heavyweight, their

insulation design is difficult, and an iron core or multi-grade capacitance voltage division structure

is generally adopted. As a result, the detection accuracy of transformer is reduced, a huge phase

difference exists between detection signal and voltage signal to be measured, and the detection

signal cannot accurately and timely reflect the change of conductor voltage signal to be measured.

By aiming at the current problems of electric transformation, based on electrostatic induction

principle, this paper designed a non-contact voltage sensor and gained detection signal of the

sensor through electrostatic coupling for the electric field generated by electric charges of the

conductor to be measured. The insulation structure design of the sensor is simple and its volume is

small; phase difference of sensor measurement is effectively reduced through optimization design

of the electrode; and voltage division ratio and measurement accuracy are increased. The voltage

sensor was tested on the experimental platform of simulating three-phase transmission line.

According to the result, the designed non-contact voltage sensor can realize accurate and real-

time measurement for the conductor voltage. It can be applied to online monitoring for the

voltage of three-phase transmission line or three-phase distribution network line, which is in

accordance with the development direction of the smart grid. © 2015 by the authors; licensee

MDPI, Basel, Switzerland.