The irregularities present in the track are the primary causes of vibration and these should be identified and the faults rectified to increase the safety of train travel. In this paper, a differential evolution technique based track measurement system is proposed to measure the health of the track. The abnormality of the track has been measured using micro electro mechanical system accelerometers which are mounted in the axle box. A new sensing method is used to estimate the exact location of the irregularity even when the signal is absent. Rail Track Measurement,Gap Measuring Device,Rail Measuring Device,Laser Measurement Device Shenyang Lubang Railway Maintenance Machinery Co.,Ltd. , https://www.srmfrailwayequip.com
The process of supplying heat is a heat transfer process, and the process of removing steam is a mass transfer process. Therefore, the sublimation drying process is essentially a process in which heat transfer and mass transfer are performed at the same time. Any process occurring in the natural world has a driving force. The heat transfer driving force in the sublimation drying is the temperature difference between the heat source and the sublimation interface, and the mass transfer driving force is between the sublimation interface and the steam trap (or cold trap). The difference in the partial pressure of steam. The greater the temperature difference, the faster the heat transfer rate; the greater the steam partial pressure difference, the faster the mass transfer (ie, the elimination of steam) rate.
When lyophilized, it is necessary to maintain the good quality of the product while achieving a faster drying rate. The latent heat required for sublimation must be transferred from the heat source through the external heat transfer process to the surface of the material to be dried, and then transferred through the internal heat transfer process to the actual occurrence of ice sublimation within the material. The generated water vapor must reach the surface of the material through an internal mass transfer process and be transferred to a vapor trap (cold trap) through an external mass transfer process. Any one process or several processes together may become the “bottleneck†of the drying process, which depends on the design of the freeze drying equipment, the operating conditions, and the characteristics of the material being dried. Only at the same time improve the heat transfer, mass transfer efficiency, increase the surface area per unit volume of freeze-dried material, can achieve faster drying rate.
Vacuum freeze-drying has many kinds of heating methods, such as contact heat transfer method, double heating method, microwave heating method, etc. Each heating method has its own characteristics. Based on the constant understanding of the essence of the freeze-drying process, people have explored a variety of heating and radiation combinations, such as conduction-radiation heating, conduction-microwave heating, and radiation-microwave heating. Its purpose is to expect to increase the drying rate and reduce energy consumption while ensuring product quality.
The advantage of vacuum freeze-drying is that it can reduce the possibility of oxidation and deterioration of materials, eliminate bacteria in materials, ensure quality, and the original shape of materials can be well preserved. The investment cost is high, but companies must follow the trend of development. Advance and continue to promote the development of the drying industry.
As with other drying methods, vacuum freeze-drying is required to maintain the continuous progress of sublimation drying, and must also meet two basic conditions, namely, the continuous supply of heat and the continuous elimination of generated steam. In the initial stage, if the material temperature is relatively high, the latent heat required for sublimation can be taken from the sensible heat of the material itself. However, with the progress of sublimation, the temperature of the material quickly falls to a temperature that is in equilibrium with the partial pressure of the steam in the drying chamber. At this time, if there is no external heating, sublimation drying stops. In the case of external heating, if the steam generated by sublimation is not eliminated in time, the partial pressure of steam will increase and the temperature of the material will increase. When the frozen point of the material is reached, the ice crystals in the material will melt. Freeze-drying can not be carried out.