Field Circumstance Research Articles

Performance of capacitive deionizing membrane distillation (CDIMD) process for the organic sewage treatment and how operating parameters can affect it

To solve the fouling issue of traditional membrane distillation (MD) technique, a newly-designed hybrid purification system integrating capacitive deionization (CDI) with MD technology was established for the organic sewage treatment in this study, namely capacitive deionizing membrane distillation (CDIMD) technology. Complexes formation via cross-linking among protein, divalent cations, and polysaccharide, an archcriminal inducing MD fouling, was remarkably alleviated in the CDIMD system considering that negatively-charged organics were clearly divided away from those divalent cations in an electric field circumstance. The CDIMD performance was deeply explored in this study focusing on the impact mechanisms of core operational parameters. An appropriate increment of feed temperature (60–65 °C) and feed flow velocity (15.72–17.82 mm/s) contributed to the anti-fouling performance of CDIMD. Considering the side reactions at voltage >1.2 v, setting working voltage at around 1.2 v seemed to be optimal for CDIMD operation. With an overall consideration of pure water production and anti-fouling performance, a properly thicker CNTs layer (40–60 μm) efficiently enhanced the fouling mitigation of CDIMD. A frequent switching of electric field direction (9/1 min) facilitated the timely regeneration of electrode and composite membranes, accordingly promoting a reliable purification of organic wastewater by CDIMD technique.

Numerical Simulation of the Electromagnetic Dross Removal Technology Applied in Zinc Pot of Hot-Dip Galvanizing Line

The forming of zinc dross floating on the surface of molten zinc in zinc pot is inevitable during hot-dip galvanizing production. The cleaning of zinc dross has always been a challenge and a difficult problem to solve. Based on the electromagnetic field theory and its application, a new electromagnetic dross removal technology was proposed, and the zinc dross driven by flowing molten zinc was possible to remove in an electromagnetic field circumstance. Through the coupling simulation of electromagnetic field and flow field, the electromagnetic force acting on molten zinc and the flow situation of molten zinc were simulated. The results showed that electromagnetic field can effectively act on the top surface of molten zinc and affect the flow of molten zinc. Different load conditions of electromagnetic field and the distance between the bottom surface of the iron core and the top surface of molten zinc related to zinc dross removal effect were discussed. Finally, the optimal application parameters of the electromagnetic dross removal technology were put forward.

Ultrafast photothermoelectric effect in Dirac semimetallic Cd3As2 revealed by terahertz emission

The thermoelectric effects of topological semimetals have attracted tremendous research interest because many topological semimetals are excellent thermoelectric materials and thermoelectricity serves as one of their most important potential applications. In this work, we reveal the transient photothermoelectric response of Dirac semimetallic Cd3As2, namely the photo-Seebeck effect and photo-Nernst effect, by studying the terahertz (THz) emission from the transient photocurrent induced by these effects. Our excitation polarization and power dependence confirm that the observed THz emission is due to photothermoelectric effect instead of other nonlinear optical effect. Furthermore, when a weak magnetic field (~0.4 T) is applied, the response clearly indicates an order of magnitude enhancement on transient photothermoelectric current generation compared to the photo-Seebeck effect. Such enhancement supports an ambipolar transport nature of the photo-Nernst current generation in Cd3As2. These results highlight the enhancement of thermoelectric performance can be achieved in topological Dirac semimetals based on the Nernst effect, and our transient studies pave the way for thermoelectric devices applicable for high field circumstance when nonequilibrium state matters. The large THz emission due to highly efficient photothermoelectric conversion is comparable to conventional semiconductors through optical rectification and photo-Dember effect.

Bacillus sphaericus exposure reduced vector competence of Anopheles dirus to Plasmodium yoelii by upregulating the Imd signaling pathway

BackgroundVector control with Bacillus sphaericus (Bs) is an effective way to block the transmission of malaria. However, in practical application of Bs agents, a sublethal dose effect was often caused by insufficient dosing, and it is little known whether the Bs exposure would affect the surviving mosquitoes’ vector capacity to malaria.MethodsA sublethal dose of the Bs 2362 strain was administrated to the early fourth-instar larvae of Anopheles dirus to simulate shortage use of Bs in field circumstance. To determine vector competence, mosquitoes were dissected and the oocysts in the midguts were examined on day 9–11 post-infection with Plasmodium yoelii. Meanwhile, a SYBR quantitative PCR assay was conducted to examine the transcriptional level of the key immune molecules of mosquitoes, and RNA interference was utilized to validate the role of key immune effector molecule TEP1.ResultsThe sublethal dose of Bs treatment significantly reduced susceptibility of An. dirus to P. yoelii, with the decrease of P. yoelii infection intensity and rate. Although there existed a melanization response of adult An. dirus following challenge with P. yoelii, it was not involved in the decrease of vector competence as no significant difference of melanization rates and densities between the control and Bs groups was found. Further studies showed that Bs treatment significantly increased TEP1 expression in the fourth-instar larvae (L4), pupae (Pu), 48 h post-infection (hpi) and 72 hpi (P < 0.001). Further, gene-silencing of TEP1 resulted in disappearance of the Bs impact on vector competence of An. dirus to P. yoelii. Moreover, the transcriptional level of PGRP-LC and Rel2 were significantly elevated by Bs treatment with decreased expression of the negative regulator Caspar at 48 hpi, which implied that the Imd signaling pathway was upregulated by Bs exposure.ConclusionsBs exposure can reduce the vector competence of An. dirus to malaria parasites through upregulating Imd signaling pathway and enhancing the expression of TEP1. The data could not only help us to understand the impact and mechanism of Bs exposure on Anopheles’ vector competence to malaria but also provide us with novel clues for wiping out malaria using vector control.

High field phase transition of cathode material Li2MnSiO4 for lithium-ion battery

The magnetic properties of the candidate lithium-ion battery cathode materials Li2MnSiO4 have been studied experimentally using static and pulsed high magnetic fields. A field-induced magnetic transition is observed in low temperature region, in which a saturation magnetization is observed above 27 T which confirms that the Mn-ion has a dominant low spin state with a saturated magnetic moment of ∼3.1 μB/Mn. With the change of temperature and magnetic field, the Li2MnSiO4 shows a complex magnetic phase transition. Considering to the coupling between spin, charge and orbital, the field-induced magnetic transition may affect the charge-discharge behavior of the cathode material, thus, the study is expected to explore the possibility and stability of the candidate lithium-ion battery cathode materials used in the low temperature and high magnetic field circumstance and its performance degradation.

Experimental Studies of Current Decay in a Flux Pumped HTS Magnet Subject to Travelling Magnetic Fields

Superconducting magnet, which provides a steady magnetic field if operated in persistent current mode (PCM), can be applied in MRI/NMR, motors, and other power devices. However, due to the joint resistance of high temperature superconducting (HTS) magnet manufactured by coated superconducting tapes, it would be difficult to realize PCM operation. Moreover, the ac loss would affect the decay characteristics of HTS magnet when applied in the ac magnetic field circumstance. In this paper, a shorted racetrack HTS magnet was manufactured and charged by a flux pump. The current decay of the pumped HTS magnet with and without travelling magnetic field was investigated. Results show that subjected to travelling magnetic field, the current decay of the PCM HTS magnet cannot be simply explained by the existence of joint resistance, other factors, which are more important, must be figured out. To understand the underlying mechanism, the dynamic resistance explanation has been adopted and verified by numerical calculation.

Fault Diagnosis System of Electrical System Based on Classified Hierarchical Model

In order to promote the maintenance and support capability of modern military engineering equipment under the complicated field circumstance, the fault diagnosis expert system is proposed based on neural network. The fault diagnosis characteristics of whole machine as well as the failure mode and mechanism of the electronic system are investigated in detail. Then the structure of classified hierarchical diagnosis model is studied, and the knowledge base of the fault diagnosis system is also been accomplished. The forward reasoning mechanism of the fault diagnosis expert system is bring forward based on neural network intelligent reasoning that can achieve fuzzy input and multiple fault diagnosis. This work is applied in military engineering fields. Hence it effectively enhances the fault maintenance, diagnosis and support capabilities of the military troops.

Monte Carlo simulations on phase change in aggregate structures of ferromagnetic spherocylinder particles

A suspension of ferromagnetic rod-like particles can be expected to exhibit strong magneto-rheological characteristics, which is a significantly important factor for application of magnetic particle suspensions to mechanical dampers and actuators. Hence, in the present study, we address a suspension composed of ferromagnetic rod-like particles in thermodynamic equilibrium. We here investigate the dependence of the phase change in aggregate structures on the various factors such as magnetic field strength, magnetic particle–particle interaction strength and volumetric fraction of magnetic particles. Monte Carlo simulations have been carried out to obtain results of snapshots, radial distribution function and order parameter of the system. In a weak applied magnetic field, the magnetic rod-like particles tend to aggregate to form raft-like clusters if the magnetic particle–particle interaction is much larger than thermal energy. If the magnetic field is increased, these raft-like clusters drastically dissociate into single-moving particles, that is, the phase change in aggregate structures arises. Moreover, the phase change in the aggregate structures is induced by the magnetic particle–particle interaction strength, from no cluster formation to long and thick chain-like clusters, in a strong applied magnetic field circumstance. As the length of the magnetic rod-like particles is increased, the orientational configuration comes to have a more significant effect on the cluster formation.

Design and Optimization of Concrete-Filled Steel Tube Arch Bridge Using Cable-Hoisting Method

Based on the hoisting construction feature of large hinge-support tower and field circumstance, the cable hoisting system for Meng-dong river grand bridge at the west of Hunan province is designed. Studying on cable hoisting system design and construction of the CFST arch bridge, the paper takes systematic analysis and calculations on the key construction technology of the CFST arch bridge, and puts it in practice successfully which provides experience for the similar long—span bridge construction of the follow.

Electromagnetic Field Transmission Characteristics in High Frequency by Particle Effect

To estimate the electromagnetic field circumstance of the particle-shaped material in high frequency electromagnetic field application, the penetration scale length is shown in this paper by means of micro-sized calculation model, in which the eddy current and displacement current is considered and finite element method based on jω method is used. From the calculation results, the following items are introduced. The eddy current, which is induced by external magnetic field, plays an important role, when electromagnetic field is applied to the particle-shaped materials in high-frequency. It is important that the electromagnetic field is in the high frequency domain where the side wave occurs, in order that the electromagnetic field is transmitted deeply into the particle-shaped materials. When the electrical conductivity of the particle substance of the particle-shaped materials varies, the eddy current distribution within the particle is different and the estimated penetration scale length has a peak value. In the high electrical conductivity, the eddy current has a clean circle within the particle, which flows around the external magnetic field direction. High Joule energy consumption is obtained. In the electrical conductivity at which the penetration scale length has a peak value, the eddy current flows in one-sided within the particle and small Joule energy consumption is obtained. In the low electrical conductivity, the eddy current flows in the same direction within all area of the particle, and high Joule energy consumption is obtained. The particle begins to behave like a dielectric and then the continuity of eddy current is not formed.

An ultrasonic on-line test method for detecting remotely and automatically energised porcelain post insulators in high-voltage substations

The fracture of ceramic post insulators in substations is a very important factor which disturbs the normal working of high-voltage (HV) substations. Every year there are some serious grid accidents caused by the fracture of ceramic post insulators in some countries. The fracture is usually caused by the propagation of the crack. Therefore, in this paper, an ultrasonic on-line test method for inspecting automatically the internal crack of the energised porcelain post insulator at 220 kV substations is introduced to prevent the fracture. The correlative ultrasonic detection technology of the energised ceramic post insulators is investigated. Furthermore, an inspection mechanism and robotised inspection system with good insulation safety property and electromagnetic compatibility (EMC) performance are designed. The experimental results show that, even in the high-voltage and strong magnetic field circumstance in substations, the live-line remote inspection of energised porcelain post insulators can be accomplished safely, conveniently, steadily, reliably and effectively with this method.

STUDY ON PROPERTIES OF ELECTRORHEOLOGICAL FLUID AND ITS APPLICATION IN MACHINING VIBRATION CONTROL

The better mechanical properties of Electrorheological fluid (ERF) are critical for its engineering application. In this paper, the effects of electric field strength and circumstance temperature on steady flow characteristic of ERF are analyzed; the effects of electric field strength, vibration amplitude, vibration frequency and circumstance temperature on ERF's dynamic mechanical properties are investigated using orthogonal tests. In addition, the ERF damper of lathe tool slide worked on shear-mode is developed; the turning experiments with the damper are performed in order to validate the suppressive effect of vibration. The experimental results demonstrate that ERF dampers can decrease the machining vibration response effectively.

An earthquake data acquisition system for mobile observation

Besides the same performance as the earthquake observation system possess used on the fixed earthquake station, such as wide dynamic range, high resolution, following special features are necessary for the earthquake data acquisition system (EDAS) applied for mobile observing in order to suit for running in the field: a) Reliability. The EDAS must work stably long time without being cared. b) Adaptability to the field environments. Earthquake observing in the field often encounters awful environments, such as dampness, dust, and abnormal climate, so how to make the instrument run well in the field circumstance must be considered. c) Ability of anti-vibration. The instrument for outdoor application must keep free from being destroyed during being transported long distance to the destination. d) Storage capacity. Because seismological data is large, how to store and collect the large amount data conveniently from the field is always a difficult point in the mobile observing system design. e) Automation. Timing and positioning automatically is necessary in the field. f) Power consumption. To reduce the power con-sumption as low as possible is very important to the mobile instrument which are powered with battery. g) Ability of testing itself. Testing itself automatically make it convenient in the fieldwork. h) Portability. The instrument must be portable and simply operated.