Experimental Investigations on Charge Induction and Microseismic Characteristics of the Coal and Rock under Different Loading Rates

The research on charge induction and microseismic characteristics of coal and rock under different loading rates is of great significance for rockburst prediction. In this study, the coal and sandstone samples from the No. 11 mine of Pingdingshan Coal Mine are prepared. The charge induction and microseismic synchronous comprehensive monitoring system is built. The uniaxial compression tests of coal and sandstone samples under the different loading rates are conducted. The charge induction and microseismic signal characteristics in the deformation and fracture process of the coal and rock under the different loading rates are studied. The results show that, with the increase of loading rate, the compressive strength of the coal and rock samples increases and the time from the peak stress to instability failure becomes shorter. At the same loading rate, the softening failure stage time of coal is longer than that of sandstone. With the increase of loading rate, the duration of charge-induced signal and microseismic signal is longer and the events’ number and amplitude of charge signal and microseismic signal increase in the deformation and fracture process of the coal and rock. Before the instability failure, the charge-induced signal and microseismic signal have both synchronous and asynchronous signals, and the amplitude of charge-induced and microseismic signals in each channel is different, which is related to the distance from the position of each sensor to the fracture point of the sample. During the instability failure, the charge induction and microseismic signals of each channel are generated synchronously, and the signal amplitude reaches the maximum values of 50 pC and 6 × 10−3 m/s at the same time. With the increase of specimen stress, the dominant frequency of microseismic signals first increases and then decreases, while the amplitude of dominant frequency increases synchronously. The dominant frequency amplitude of microseismic signals is the largest in instability failure. With the increase of loading rate, the spectrum amplitude of microseismic signals changes little in the compaction stage, but the spectrum amplitude increases in other stages. At the same loading speed, the events’ number of the microseismic signal of coal samples after peak stress is more than that of sandstone samples, and the signal amplitude is also larger. However, the spectrum distribution range of microseismic signals of coal samples is wider than that of sandstone samples, and the spectrum amplitude of coal samples is lower than that of sandstone. With the increase of loading rate, the time of the first generation of high-amplitude signals is advanced, and the stress of specimen becomes smaller when the first generation of high-amplitude signals occurs. With the increase of loading rate, the duration of microseismic and charge signal is longer, and the mean square amplitude of charge signal is larger.

Dust Telescopes for Dust Astronomy

<p>Dust Astronomy investigates the nature and the origin of dust particles in space. The particle size distribution ranges from nanodust to approximately 100 micrometer. The study of the elemental and/or chemical composition of the particles together with the knowledge about their origin provides insights into many disciplines. Dust Astronomy is an interdisciplinary working field, which includes Solar System Science, Interstellar Medium studies and Astrobiology. A basic tool for these studies are Dust Telescopes.</p> <p>Dust Telescopes are in-situ instruments to characterize individual dust particles by their velocity vector, size and composition. They are based on impact ionization used for time-of-flight compositional analysis and on charge induction for particle speed and size measurements.<span class="Apple-converted-space"> </span></p> <p>In this sense, already the Cassini Cosmic Dust Analyzer (CDA) was a simple Dust Telescope, which successfully characterized the dust environment at Saturn. Now, future missions go even further. In the next years the missions DESTINY+, EUROPA and IMAP will launch. In this talk, a summary is given about the capabilities of Dust Telescopes with a focus on the DESTINY+ Dust Analyser (DDA). DDA is a medium size instrument with a target diameter of 26 cm. A two-axis articulation allows to track dust RAM directions. Larger Telescopes like the record breaking LAMA instrument, developed especially for the measurement of low interstellar dust fluxes, and the instruments for the probes IMAP and EUROPA are compared with DDA.</p> <p>The paper will address questions about the detection of nanodust or, what is a good instrument approach for a Dust Observatory? What are the instrumental challenges for an Interstellar Probe?</p>

Formulation, Development and Assessment of Novel Phyto-Elastosomes Loaded with Devil’s Claw Extract

Background: Management of arthritis requires frequent administration of medications at high doses that may lead to unwanted side effects and diminished patient adherence to the therapy. Devil’s claw extract, a herbal medicine from the Kalahari sands possess similar therapeutic efficacy with less side effects as the commercialized NSAIDs. The objectives of this study were to formulate, develop and assess novel phyto-elastosomes loaded with Devil’s claw extract in order to combat the toxicity levels associated with Devil’s claw and enhance penetration of harpagoside to intended targeted site.Methods: Screening studies were undertaken to determine the ideal amount of Tween® 80, cholesterol, ethanol, diacetyl phosphate and the pH of the hydration medium necessary to produce stable Devil’s claw-loaded phyto-elastosomes. Parameters monitored were particle size, polydispersity index, zeta potential, entrapment efficiency and deformability index.Results: The use of 20 % v/v ethanol was sufficient to produce novel phyto-elastosomes capable of deforming with minimal size alterations. Hydration of thin films in acidic solution produced phyto-elastosomal dispersions with high entrapment efficiency. The presence of cholesterol impeded harpagoside entrapment and increased cholesterol content affected the stability of vesicles by causing agglomeration. Conversely, increasing Tween® 80 concentration promoted harpagoside entrapment. Diacetyl phosphate promoted the stability of vesicle through charge induction.Conclusions: Development of Devil’s claw loaded phyto-elastosomes is useful in ensuring harpagoside reach the target site of action in arthritis-affected patients. Incorporation of these elastic vesicles in transdermal dosage forms may significantly improve the management of arthritis in the near future.

An Electric Field Microsensor with Mutual Shielding Electrodes

This paper proposes an electric field microsensor (EFM) with mutual shielding electrodes. Based on the charge-induction principle, the EFM consists of fixed electrodes and piezoelectric-driving vertically-movable electrodes. All the fixed electrodes and movable electrodes work as both sensing electrodes and shielding electrodes. In other words, all the fixed and movable electrodes are sensing electrodes, and they are mutually shielding electrodes simultaneously. The movable electrodes are driven to periodically modulate the electric field distribution at themselves and the fixed electrodes, and the induced currents from both movable and fixed electrodes are generated simultaneously. The electrode structure adopts an interdigital structure, and the EFM has been simulated by finite element methods. Simulation results show that, since the sensing area of this EFM is doubled, the variation of induced charge is twice, and therefore the output signal of the sensor is increased. The piezoelectric material, lead zirconate titanate (PZT), is prepared by the sol–gel method, and the microsensor chip is fabricated.

An Identification Method for Rotor Direction Based on Charge Induction

The detection of rotor motion is always key to ensure the normal operation of industrial sewing machines. This paper presents a novel method for rotor detection based on charge induction mechanism, which is suitable for industrial environments with high noise and electromagnetic radiation and is easy to install. Firstly, the principle of measuring rotor rotation based on charge induction is given. Then, the detection model of rotor direction identification based on two detection electrodes is established. Finally, details are given of the detection circuit design and the experiment that was carried out. The results show that the proposed method can effectively identify the noncontact rotor direction with and without occlusion, indicating that the method has excellent anti-interference capability. The accuracy of the method can be further improved by increasing the sampling rate and sampling points of the system.

Electrostatic Induction Spray-charging System (Embedded Electrode) for Knapsack Mist-blower

The introduction of electrically charged sprays in agricultural application has become inevitable for better control on droplet transference with reduced drift with less spray chemical requirements. The study was under taken to develop an electrostatic induction spray charging system as attachment to knapsack mist-blower. A high voltage generator was fabricated on the basis of Cockcroft-Walton voltage multiplier principle with input of 6 V DC battery. A self-atomizing hydraulic nozzle was developed to deliver the droplet spectrum required for effective electrostatic charge induction. The prototype was evaluated for charge to mass ratio (mC. kg-1) at five electrode potentials (1 kV, 2 kV, 3 kV, 4 kV and 5 kV) at four electrode placement positions from atomization zone (0, 5, 10 and 15 mm). The charge mass ratio (CMR) value of spray cloud was measured using Faradays Cage at five positions from nozle tip (50, 100, 150, 200 and 250 cm). The electrode voltage potential at 5 kV at its position 5 mm from the atomization zone shown the maximum CMR value of 1.088 mC.kg-1. In contrast with commercial system (ESS-MBP90) it was observed that except at 50 cm distance, the developed charging system, at 4 kV and 5 kV, surpassed commercial system in CMR from 100 cm to 250 cm distances. The droplet spectrum of the developed system was analysed and observed that the size of droplets were 100 to 200 µm. The developed system found to be cost effective and significantly consistent over the commercial one.