Grain Relativity Humidity Real-Time Prediction Based on Different Saturated Humidity Models in the Process of Storage
A mathematical model was selected and established based on the granary internal temperature and humidity real-time monitoring. In the experiment, the relative humidity of different water content corns were predicted by using different saturated vapor pressure formula and select the fittest model by comparing with the calculations and the test results. The humidity calculated by the saturated vapor pressure at formula 3 was closest to the actual measurement in them. Using the model it was possible to predict the evolution of grain relativity humility. During the experiment process, the calculation appeared the fluctuation because the internal humidity of grain was greatly influenced by the temperature and relativity humidity of the environment.
The selection of sorption isotherm equations for wheat based on the fitting of available data
Abstract Thirty-three sources of EMC/ERH data for wheat were identified, from which 1109 experimental points were extracted. Nineteen sources covered a range of temperatures. Five commonly cited EMC/ERH equations, Chen-Clayton, Modified-Chung-Pfost, Modified-Henderson, Modified-Oswin and Strohman-Yoerger, were compared for their ability to fit 29 sets of wheat data from these 19 sources. The Modified-Chung-Pfost and the Modified-Oswin equations gave the best fit for r.h. = f ( M , T ) and M = f (r.h., T ) respectively. Both equations were then used to fit sub-sets of the data comparing adsorption, desorption, low temperature, hard, soft and durum varieties with the overall fit to the data. The adsorption and desorption equations gave quite distinct curves. The low temperature fit did not differ greatly from the overall. Amongst the varieties, the hard wheat at low temperature showed the greatest difference from the overall fit. The larger data set than previously available and the equations fitted provide a sound basis for future work on the drying and storage of wheat.
Failure analysis for poor solderability of Au surface of PCB
Nonwetting is one of the common problems and is always rejected in electronic assemblies. ENIG pads of a PCBA exhibited nonwetting after lead-free reflow soldering. With the aid of stereomicroscope, SEM&EDS and XRF, a series of analysis was performed. And after visual inspection, surface and cross section analysis, thickness measurement and solderability test, it can be inferred that oxidation of plating surface was the main reason for nonwetting, and corrosion in Ni plating caused an adverse impact on solderalibity.