A new dynamic method for measuring hydrogen partial pressure in molten aluminum alloy

Hydrogen partial pressure is an important parameter to calculate hydrogen concentration levels in molten aluminum alloy. A new dynamic method for measuring hydrogen partial pressure in molten aluminum alloy is studied. Dynamic and rapid measurement is realized through changing the volume of the vacuum chamber and calculating the pressure difference ΔP between the theoretical and measured pressures in the vacuum chamber. Positive ΔP indicates hydrogen transmits from melt to vacuum chamber and negative ΔP means the reverse. When ΔP is equal to zero, hydrogen transmitted from both sides reached a state of dynamical equilibrium and the pressure in the vacuum chamber is equal to the hydrogen partial pressure in the molten aluminum alloy. Compared with other existing measuring methods, the new method can significantly shorten the testing time and reduce measuring cost.

大型运载火箭重量特性快速测量技术研究

In order to further adapt to the task requirements for rapid testing and high-density launches,the LM-5 series of rocket boosters have adopted an automated acquisition and measurement process for key parameters such as the weight and centroid of the launch vehicle.A fully automatic rapid measurement technology for the weight characteristics of the rocket,consisting of a measurement system,a control system,an execution system,and a data processing system,has been developed and incorporated.This does not just achieve the adjustment of the overall assembly attitude of the rocket body and the measurement of the center of mass,but also greatly reduces the workload in the traditional measurement operations such as for assembly erection and rail transfer.Thus improving the general convenience,while greatly improving the reliability and measurement accuracy of product installation,which further promotes the popularization of an intelligent measurement technology application.

Fast-Response Fiber-Optic FPI Temperature Sensing System Based on Modulated Grating Y-Branch Tunable Laser

In this paper,a cost-effective and miniaturized instrument is proposed,which is based on a tunable modulated grating Y-branch(MG-Y)laser for rapid temperature measurement using a Fabry-Perot interferometer(FPI)sensor.The FPI sensor with a 1463-μm cavity length is a short segment of a capillary tube sandwiched by two sections of single-mode fibers(SMFs).This system has a broad tunable range(1527 nm-1567 nm)with a wavelength interval of 8 pm and a tuning rate of 100 Hz.Temperature sensing experiments are carried out to investigate the performance of the system by demodulating the absolute cavity length of the FPI sensor using a cross-correlation algorithm.Experimental results show that the sensor can reach the response time as short as 94 ms with the sensitivity of 802 pm/C.Benefiting from the homemade and integrated essential electrical circuits,the entire system has the small size,low cost,and practical application potential to be used in the harsh environment for rapid temperature measurement.

Rapid dissociation and on-site saturation evaluation of methane hydrate sediment samples for natural gas hydrate exploitation

Natural gas hydrate is a kind of clean energy with huge reserves,and the saturation(volume percentage of hydrate in pore space of sediments)is the key parameter for determining whether the reservoir is worthy of exploitation.In this work,rapid hydrate dissociation by the combination of heat injection and NaCl inhibitor addition was studied,and an on-site evaluation method for hydrate saturation in sediment samples was proposed by using a core sampler to transfer hydrate samples under pressure.The results showed that the average gas production rate per unit volume was increased significantly to reach 7.22 L/Lr$min-1 by the injection of NaCl aqueous solution with 50.9C,which was attributed to the increase of the chemical potential to further accelerate the rate of hydrate dissociation in the presence of NaCl.Furthermore,for the measurement of methane hydrate samples saturation with a volume of 673 cm3(which contained 1.4 mol hydrates with the saturation of 58%),hydrate saturation could be accurately achieved within 30 min with a relative error lower than 11.7%This work may provide new thoughts for on-site saturation evaluation and rapid dissociation of hydrate samples during natural gas hydrate exploitation.