Infrared microthermometry of fluid inclusion in sphalerite:A case study of the Xinqiao deposit in the Middle-Lower Yangtze metallogenic belt

Infrared microthermometry allows direct measurement of fluid inclusions hosted in opaque ore minerals and can provide direct constraints on the evolution of ore-forming fluids.This study presents infrared microthermometry of spherite-hosted fluid inclusions from the Xinqiao deposit in the Middle-Lower Yangtze Metallogenic Belt and sheds new light on the ore genesis of the deposit.Considering that infrared light may lead to non-negligible temperature deviations during microthermometry,some tests were first conducted to ensure the accuracy of the microthermometric measurements.The measurement results indicated that using the lowest light intensity of the microscope and inserting an optical filter were effective in minimizing the possible temperature deviations of infrared microthermometry.All sphalerite-hosted fluid inclusions from the Xinqiao deposit were aqueous.They show homogenization temperature ranging from~200 to 350℃,but have two separate salinity groups(1.0 wt%-10 wt%and 15.1 wt%-19.2 wt%NaCl equivalent).The low-salinity group represents sedimentary exhalative(SEDEX)-associated fluids,whereas the high-salinity group results from modification by later magmatic hydrothermal fluids.Combined with published fluid inclusion data,the four-stage fluid evolution of the Xinqiao deposit was depicted.Furthermore,our data suggest that the Xinqiao deposit was formed by twostage metallogenic events including SEDEX and magmatic-hydrothermal mineralization.

A Novel Insulator and Its Characteristics

Both the ceramic and the composite insulators have their own advantages and disadvantages when compared with each other. It is a reasonable idea to combine their merits together to design a novel insulator. The key measure of the novel insulator suggested in this paper is to add an annular metal sheet coated with high temperature vulcanisation (HTV) silicone rubber (SIR) at the base of the traditional ceramic insulator cap. The HTVSIR covering on the exterior of the metal sheet can lengthen the creepage distance. The metal sheet can uniform the electric stress, reduce its maximum value and modify its direction on one insulator unit and acts as equalizing ring on an insulator string. The factors stated above are the main reasons why the novel insulator has better insulating performance, including lower leakage current and flashover voltage, especially under polluted conditions. Simultaneously, the novel insulator can overcome the disadvantages of the ordinary remedies which have been widely used to improve the performance of ceramic insulators against pollution. The experimental results obtained in the laboratory were in good agreement with the theoretical analysis and demonstrated the novel insulator's effectiveness.

Numerical simulation of flow characteristics in settler of flash furnace

A computational fluid dynamics （CFD） simulation was carried out with CFX4,3 to investigate the melt flow and temperature distributions in the settler of a flash furnace. Sixteen cases of one slag tap hole adopted with one matte tap hole （1-to-l） and one slag tap hole adopted with two matte tap holes （1-to-2） operation modes were modelled. The simulation results show that the melt flows are similar in both two operation modes, but evident circulations can be found in the case of the 1-to-2 operation mode. The combination modes of the slag and matte tap holes are found to have a significant effect on the temperature distributions of the melt. The melt temperature is more uniform in the case of the 1-to-2 mode. Selection of a matte tap hole farther away from the inlet is more conducive to achieve a uniform distribution of the melt temperature in the settler in nractical tannine oneration

火种

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并州夜色

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Formation Mechanism and Characteristics Research of Ball Lightning Based on Vortex Model

The strange characteristics of ball lightning are considered as a question hard to explain. In order to solve the problem, in this paper a complete model of plasma vortex is presented for the ball lightning. By ideal MHD equations, through imposing disturbance to plasma column, the possibility of sausage and kink instability of the lightning channel is analyzed from the perspective the minimum potential energy. The conclusion is that the kink instability （m = 1） is most prone to occur. And when instability occurs, because of the difference of the magnetic field in the twisted area, the magnetic pressure makes the trend further and therefore forming the plasma vortex that may eventually turn into ball lightning if the energy of the vortex is large enough. The existence of the vortex makes ball lightning have a short period of time stability. By the proposed model, the ball lightning features that are hard to understand in the past are explained. In this paper, the reason for bead lightning is also explained from the perspective of the sausage instability.

OBSERVATIONAL STUDY OF LIGHTNING CHARACTERISTICS IN HAIL-PRODUCING CLOUDS

1 INTRODUCTION Lightning is a phenomenon of atmospheric electricity with convective storms. Since the 1960＇s, its characteristics during weather processes of torrential rain, hails and tornadoes have been widely studied and a lot of attempts made to probe into the mechanisms responsible for the formation of lightningIll, giving rise to two theories explaining the lightning genesis, from the points of convection and ice-phase precipitation, respectively, In addition, some studies show, from various aspects, that lightning of severe convective weather. indicates the occurrence There has been lack of concrete indices to identify lightning features and determine hail-producing clouds. Apart from diagnostic . analysis based on conventional data , this work studies the evolution of lightning in 11 hails using relevant records and Doppler radar information and sums up a number of lightning features for hail weather in the sub-plateau area of Gansu province by taking as the criterion whether convective clouds cause hails in determining hail-producing clouds. In Gansu, hailproducing clouds usually originate from mountainous areas, follow fixed routes of movement and are often accompanied with heavy rainfall as they produce hails in more than a spot in the life cycle. To mitigate losses, it is essential to use scientific detectors to warn of hail weather in advance and conduct weather modification to check the growth of hails. The weather radar is an efficient tool to watch and forecast severe convective weather like hails, for it not only detects the structure but also tracks down the generation and evolution of hail-producing clouds to aid in isolating where the hail falls. It is, however, not realistic to perform real-time radar watch in Northwest China and existing radars are not capable of observing thunderstorms. Costing relatively low to purchase and maintain, the lightning locator has wide range of measurement and works nonstop without human attendance, making it easier to watch large-scale convective clouds in the region. With hails, heavy rains and tornadoes isolated and warned of based on features captured by the locator, operations of weather modification can be made more efficient with further identification from radar echoes and observed facts of electric mechanisms can be better understood for convective weather.

Tropospheric Scintillation Estimation Using 10 Years Meteorological Data

This paper presents estimation of tropospheric scintillation based on ITU-R model from previous 10 years meteorological data.Scintillation As(p) is critical in designing of microwave links for achieving optimal performance.There are many phenomenons that cause degradation to signal during transmission through the earth's atmosphere one of them is scintillation.Scintillation estimation is based on measurements of surface temperature T and relative humidity RH.Input parameter for ITU-R scintillation estimation model is the monthly average of wet part of refractivity Nwet.MATLAB software tool is employed to show the results for tropospheric scintillation in various seasons for time percentage p and frequencies ranging from 4GHz to 20 GHz.

Effect of Surface Charge on Flashover for Oil-Pressboard Insulation under AC-DC Combined Electric Field

For converter transformer, AC-DC combined electric field can trigger space charge accumulation on oil-impregnated pressboard interface. The accumulation of space charge on oil-pressboard interface can result in electric field distortion, trend to trigger surface discharge of barriers. This paper studied the influence of surface charge on flashover voltage of oil-impregnated pressboard under AC-DC combined electric field. The study finds that the flashover voltage of oil-pressboard interface under negative polarity DC superimposed AC electric field is higher than that.of positive DC superimposed AC voltage to form composite electric field. It was found that homopolar surface charge has been accumulated on the interface of oil-pressboard with positive or negative DC voltage through measuring surface potential by the electrostatic capacitive probe. The surface charge produced electric field in the opposite direction, which weakening the synthetic electric field strength. What＇s more, under the same conditions, the negative surface charge density oil-pressboard is much larger than the positive.

Occurrence conditions of positive cloud-to-ground flashes in severe thunderstorms

The purpose of this study was to understand the reasons why frequent positive cloud-to-ground(+CG) flashes occur in severe thunderstorms. A three-dimensional dynamics-electrification coupled model was used to simulate a severe thunderstorm to permit analysis of the conditions that might easily cause +CG flashes. The results showed that strong updrafts play an important role in the occurrence of intracloud flashes. However, frequent +CG flashes require not only strong updrafts but also strong downdrafts in the lower cloud region, conditions that correspond to the later phase of the mature stage and the period of the heaviest solid precipitation of a thunderstorm. During this stage, strong updrafts elevated each charge area in the updraft region to a higher level, which resulted in an inverted tripole charge structure. A wide mid-level region of strong positive charge caused largely by positively charged graupel, presented in the middle of the updraft region because of a non-inductive ice-ice collisional charging mechanism. The charge structure in the downdraft region was consistently more complex and revealed several vertically stacked charge regions, alternating in polarity. Much of the graupel/hail outside the updrafts was lowered to cloud-base by strong downdrafts. In this area, the graupel/hail was charged negatively because of the transportation of negatively charged graupel/hail from higher regions of negative charge in the updrafts, and via the inductive charging mechanism of collisions between graupel/hail and cloud droplets at the bottom of the cloud. Consequently, a large region of negative charge formed near the ground. This meant that +CG flashes were initiated more easily in the lower inverted dipole, i.e., the middle region of positive charge and lower region of negative charge. Frequent +CG flashes began almost synchronously with dramatic increases in the storm updrafts, hail volume, and total flash rate. Therefore, the occurrence of +CG flashes appears a good indicator of storm intensification and it could have some use as a predictor of severe weather in the form of hail.

Exergetical Analysis of Organic Flash Cycle with Two-Phase Expander for Recovery of Finite Thermal Reservoirs

In this work exergetical performance analysis is carried out based on the second law of thermodynamics for organic flash cycle(OFC) using a two-phase expander instead of throttle expansion in order to recover efficiently finite thermal reservoirs.The exergy destructions(anergies) at various components of the system are theoretically investigated as well as the exergy efficiency.Results show that the anergy of heat exchanger or two-phase expander decreases while the anergy of throttle valve increases with increasing flash temperature,and the exergy efficiency has an optimum value with respect to the flash temperature.Under the optimal conditions with respect to the flash temperature,exergy efficiency increases with the heating temperature and the component having the largest exergy destruction varies with the flash temperature or heating temperature.