New corona-electrostatic separator with two coaxial vertical cylindrical electrodes for sorting conductors and non-conductors from granular mixtures

The micro-force measurement system based on electrostatic force using a pair of precision coaxial cylindrical electrodes as a force generator is proposed. However, there is axes deviation between the inner and outer electrodes inevitably, which can cause a change of the capacitance value. In this paper, a system is designed to measure and adjust the coaxiality of the coaxial cylindrical electrodes. After that the multidimensional adjustment stage is used to adjust the inner and outer electrodes to make them coaxial, it has a precision of 5 µm to adjust the eccentric error, and 0.030° to adjust the tilt error. A reasonable scheme is designed to calibrate the capacitance gradient, the experiment results show that after adjusting the inner and outer electrodes coaxial, the relative standard deviation in multiple measurements can be less than one over a thousand. With this measurement and adjustment scheme, the capacitance gradient value can get a good repeatability.

Corona discharge is relatively low intensity and power electrical discharges that occur at, above or below atmospheric pressure, which has been extensively used for many applications. The model of steady-state corona in coaxial cylinder electrode is employed to explore the temperature effect on the voltage-current characteristics. This article is attempted to provide a comprehensive understand of the temperature effect on corona discharge. The voltage-current characteristics for 0.01 cm 0.1 cm and 1 cm radius inner electrode are evaluated. The computational results show that with the increase of temperature, the inception decreases pronouncedly. The effective ionization coefficient shows a notably the monotonous trend with the increase of temperature. Under the identical voltage, the amplitude of current gradually increases as the increase of temperature.

With two minimal models, I study how electrode curvature affects the response of electrolytes to applied electrostatic potentials. For flat electrodes, Bazant etal. [Phys. Rev. E 70, 021506 (2004)PLEEE81539-375510.1103/PhysRevE.70.021506] popularized the RC timescale λ_{D}L/D, with λ_{D} being the Debye length, 2L the electrode separation, and D the ionic diffusivity. For thin electric double layers near concentric spherical and coaxial cylindrical electrodes, I show here that equivalent circuit models again predict the correct ionic relaxation timescales. Importantly, these timescales explicitly depend on both electrode radii, not simply on their difference.

Effect of O 2 on NO removal by ammonia radical injection using one-cycle sinusoidal power source

Parametric instability of conducting, slightly viscous liquid jets under periodic electric fields

As an application of the ERF to a practical device, coaxial twin rotary cylinders, in which the rotation of an inner driving cylinder is transmitted to an outer rotary cylinder through the medium of an ERF, was designed, and the revolution rates of both cylinders were examined. As another application, a simple shock absorber having coaxial cylindrical electrodes without the bypass was designed and the falling time of an inner moving rod was measured. The quantitative relationship between the applied electric field and the revolution rate and the falling time was obtained experimentally.

This paper presents design and construction of the ozone generator based on a resonant converter. Ozone is caused by the combination of 3 oxygen atoms. Ozone gas is widely used in the industry for killing bacteria, viruses, and protozoa. The ozone gas doesn’t cause residual pollution. The ozone gas can be produced from corona discharge on the area with high electrical field stress. In this paper, the resonant converter was developed for high voltage generation on coaxial cylindrical electrodes which are utilized to produces ozone gas. The resonant converter divided into 2 parts. The first part is the control circuit and the second part is the power circuit. The power circuit was used to convert AC voltage to AC voltage with other frequencies. Additionally, the converter can generate a square voltage with adjustable frequency for finding the resonant frequency. From the experiment, the resonant converter can produce ozone gas effectively.

As the chromatic error of focus has the same sign in all electron lenses with straight axis, achromatic combinations do not exist. It is shown, however, that systems with curved axes can be designed which are equivalent to centred systems in the gaussian approximation, but have chromatic error of opposite sign, and thus may be useful as correcting elements. Systems with a helical axis, with a helical electrostatic field so shaped as to eliminate first-order astigmatism, have particular advantages In such systems images of unit magnification are produced at equal intervals along the helical axis. Under certain conditions the transverse chromatic shift can be made zero in every second, or third,... image, while the longitudinal error of focus can be given any negative value by suitable choice of the pitch. Such systems may find application in secondary emission and dark-field electron microscopes, and particularly in diffraction microscopy. At a certain pitch the chromatic error becomes infinite. This system is particularly easily realized by means of two coaxial cylindrical electrodes. It is useless as a chromatic corrector, but may find applications as a velocity spectrograph.

The characteristics of the glow discharge in air between coaxial cylindrical electrodes in the presence of a non-homogeneous axial magnetic field are described. With the outer cylinder as cathode the discharge is narrow and takes place near the position of maximum magnetic field. If the cathode is cut transversely into halves dividing the discharge there may be a negative incremental resistance between these halves. This negative resistance may be used as the basis of an oscillator working with an efficiency of about 70 per cent. up to frequencies of about 100 kilocycles per second.

A high-accuracy, calibration-free technique to measure the electrical conductivity of molten oxides has been developed—the coaxial cylinders technique. Because the melt under investigation comes in contact only with metal and not with anything dielectric, the new technique enables the measurement of the electrical properties of liquids inaccessible by classical high-accuracy techniques. Two coaxial cylindrical electrodes are immersed in the melt to an arbitrary initial depth, and ac impedance is measured over a wide range of frequency. The electrodes are then immersed deeper, and ac impedance is again measured over the same range of frequency. This process is repeated at multiple immersions. The electrical conductivity is calculated from the change in measured conductance with immersion. The temperature dependence of electrical conductivity has been measured for two oxide melts: (M) 50.95 pct CaO, 12.51 pct MgO, 36.54 pct SiO2, 1733 K<T<1843 K; and (S) 24.59 pct CaO, 26.15 pct MgO, 49.26 pct SiO2, 1763 K<T<1903 K, where concentration is expressed in mole percent. Both melts exhibited behavior characteristic of ionic liquids.

Electrostatic separation is a typical multifactorial process. Its efficiency depends on the characteristics of the granular mixtures to be sorted, the feed rate, the configuration of the electrode system, the applied high voltage, the environmental conditions, and so on. The aim of this paper is to demonstrate the usefulness of computer-assisted experimental design in the optimization of such a process. The example analyzed in the paper was suggested by a typical application of electrostatic separation technique in the recycling industry: the selective sorting of metals and insulating materials from chopped wire and cable waste. The objective was to maximize the benefits from the recycling of both constituents of a binary copper-polyvinyl chloride granular mixture. A preliminary set of electrostatic separation tests, performed on a custom-designed laboratory unit, guided the choice of the starting values of the parameters considered in the computer-assisted experimental procedure of process optimization. The results of a first experiment, carried out in conformity with a fractional factorial scheme, were used for the computation of the coefficients of a linear mathematical model of the electrostatic process. The model was then employed to predict the values of the operating variables for which the optimum of the process is attained. A second experiment was performed in order to confirm the accuracy of the prediction. The procedure presented in this paper and the accompanying computer programs can be easily adapted to other electrostatic process applications.

The large volume of industrial by-products and wastes from the construction, timber and paper industries has become a serious challenge worldwide. Recycling these industrial wastes as functional materials in the construction industry is an efficient approach for sustainable development. This study presents a pretreatment approach for recycling construction and demolition waste (CDW) and industrial side-streams (such as green liquor sludge, fiber waste, flotation sand and fly ash) in order to produce a geopolymer for the 3D printing of construction materials. A treatment approach was developed for screening the residues from CDW with a maximum size of 16 mm and for a combined line treatment for industrial side streams. The treatment processes utilized suitable and economical separation techniques for the recycling of waste materials. The crushing of the screened residues resulted in a homogeneous material size that facilitates the separation of mixed wastes and simplifies the classification of materials. The combined plant enabled the cost-effective treatment of various industrial wastes in a single process unit. The results show that the economic and environmental impact of the chosen techniques, in terms of their energy consumption, is highly dependent on the treatment line, separation technique and quantity of the individual waste that is processed. These recycled industrial wastes can be used as sustainable materials for the production of geopolymer concrete, contributing to the sustainability of the construction industry.

The electrical breakdown potential of mercury vapour is measured between mild steel coaxial concentric cylindrical electrodes. The mercury vapour pressure is varied over a range of almost five orders of magnitude and the ambient temperature of both the gas and the electrodes from 297–544°K. The breakdown potential values plotted against mercury vapour pressure exhibit the normal behaviour associated with Paschen breakdown curves. For a given mercury vapour pressure the positive wire breakdown value is lower than the corresponding negative breakdown value. The lower positive breakdown is observed over a wide pressure range, and is attributed to the large difference in the values of the total secondary electron emission when changing the role of the inner electrodes from being an anode to cathode. The total secondary electron emission is calculated over a wide range of E/p 0 values. The similarity theorem is obeyed for positive and negative wire breakdown, over a very wide range of mercury vapour pressure.

The notion of sustainable and eco-friendly infrastructures is gaining impetus in the geotechnical engineering research field. Nowadays, employing recycled or waste materials, obtained from the natural sources, are widely used as an alternative method in construction in recognition of the green concept. It is evident that transport infrastructure projects require large amounts of materials and natural resources and consume large quantities of energy. On the other hand, large volumes of wastes are produced daily. In this paper, the beneficial effects of certain agricultural, domestic, industrial, construction, mineral and marine wastes in geotechnical applications, particularly in soil stabilization are discussed. Both methods of treatment are applied to improve the engineering properties of soil to make it suitable for construction. Another goal of this paper is to make a comparison between the effects of different types of waste materials for improving weak soil, and highlight the concept of sustainability to reduce energy consumption, carbon footprint, landfill cost and greenhouse gas emissions. Furthermore, many recycled materials and by-products are considered, and their advantages and drawbacks in soil stabilization are explained. In addition, the key results of many laboratory studies conducted on stabilized soil with waste materials are reported; and their effects on soil stabilization without or with a mixture of conventional stabilizers are discussed. The recent applications of wastes or recycled materials are also outlined. Finally, the future trend for employing recycled materials in infrastructure construction is presented.

Static charge generated by contact electrification can cause a wide range of undesirable consequences in our lives and in industry (e.g., adhesion of particles on surfaces, damage to electronics, and explosions). It has, however, been challenging to develop methods to prevent charging due to the vast types of materials that charge easily by contact electrification and the frequent changes in process and environmental conditions. The most common method is to use conductive materials for dissipating charge away; however, it is ineffective for many circumstances. Here, we propose a general and effective materials framework that involves a two-level consideration for preparing noncharging materials: (1) the variation of the proportion of a two-material composite and (2) the extent of stretching the composite material. This materials strategy is achieved by infusing particles within a stretchable bulk material. Importantly, the preparation of the noncharging surface for (1) is based on a novel fundamental mechanism that involves combining an appropriate amount of a material (e.g., the particles) that tends to charge positively with another material (e.g., the bulk material) that tends to charge negatively. This mechanism does not rely on conductivity; both the contacting materials naturally prevent the generation of static charge even when only nonconductive materials are involved. When the composite material is stretchable, the change in proportion of the surface coverage of the particles allows the charging response to be changed. Therefore, the variation in composition and stretching provide a wide two-dimensional parameter space for achieving noncharging response for the vast range of contacting materials that are used in industry and our lives. In addition, stretchability allows the composite material to flexibly adapt to changes in process and environmental conditions. This stretchable composite material was also demonstrated to be capable of preventing the adhesion of particles and separating particles of different materials.