Effects of total replacement of corn silage with sorghum silage on milk yield,composition, and quality

Background： In the last years, difficulties occurring in corn cultivation（i.e., groundwater shortages, mycotoxin contamination） have been forcing dairy farmers to consider alternative silages. Some experiments conducted on lactating cows have proven that the total replacement of corn silage with sorghum silage did not reduce milk yield.However, this kind of substitution involves supplementing sorghum-based diets with grains, to compensate for the lower starch content of sorghum silage compared to corn silage. Change of silage type and inclusion of starch sources in the diet would influence rumen fermentations, with possible effects on milk composition（i.e., fatty acid profile） and coagulation properties. A worsening of milk coagulation properties would have a negative economic impact in Italy, where most of the milk produced is processed into cheese.This study was designed to compare milk composition and quality, with emphasis on fatty acid profile and coagulation properties, in dairy cows fed two diets based on corn or sorghum silage.Results： The sorghum diet reduced milk yield（P = 0.043） but not 4% fat corrected milk（P = 0.85）. Feeding sorghum silage did not influence milk contents of protein（P = 0.07） and lactose（P = 0.65）, and increased fat content（P = 0.024）.No differences emerged for milk concentrations of saturated（P = 0.61） and monounsaturated fatty acids（P = 0.50）,whereas polyunsaturated fatty acids were lower（P 〈 0.001） for the sorghum diet. Concentrations of n-6（P 〈 0.001） and n-3 fatty acids（P = 0.017） were lower in milk of cows fed the sorghum diet. Milk coagulation properties did not differ between the two diets, except the ＂a30＂（the curd firmness, expressed in mm, 30 min after rennet addition）, that was lower（P = 0.042） for the sorghum diet.Conclusions： Feeding a forage sorghum silage, properly supplemented with corn meal, as total replacement of corn silage maintained milk composition and did not influence negatively milk coagulation properties, which have a great economic relevance for the Italian dairy industry. Thus, silages obtained from forage sorghums could have a potential as substitute of corn silages in dairy cow diets.

Effect of drum structure on particle mixing behavior based on DEM method

The optimization of the drum structure is beneficial to improve the particle motion and mixing in rotary drums.In this work,two kinds of drum structures,Lacy cylinder drum(LC)and Lacy-lifters cylinder drum(LLC),are developed on the basic of cylinder drum to enhance the heat transfer area.The particle motion and mixing process are simulated by DEM method.Based on the grid independence and model validation,the contact number between particles and wall,particle velocity profile,thickness of active layer,particle exchange coefficient,particle concentration profile and mixing index are demonstrated.The influences of the drum structure and the operation parameters are further evaluated.The results show that the contact number between particles and wall is improved in LC and LLC compared to cylinder drum.The particle velocity in LC is higher than that in cylinder drum at high rotating speed,and the particle velocity of the particle falling region is significantly improved in LLC.Compared to cylinder drum and LC,the thickness of active layer in LLC is smaller,while the local particle mixing quality is proved to be the best in the active region.In addition,the particle exchange coefficients between static region and active region in the three drums are compared and LLC is found tending to weaken the particle flow.Besides,the fluctuations of particle concentration in the active region,static region,and boundary region are weakened in LLC,and the equilibrium state is reached earlier.In addition,the overall particle mixing performance in cylinder drum,LC and LLC is analyzed.The particle mixing performance in cylinder drum is the worst,while the difference in mixing quality of LC and LLC depends on the operation conditions.

Experimental investigation of the reaction-build-up for plastic bonded explosive JOB-9003

In order to measure the shock initiation behavior of JOB-9003 explosives,Al-based embedded multiple electromagnetic particle velocity gauge technique has been developed.In addition,a gauge element called the shock tracker has been used to monitor the progress of the shock front as a function of time,thus providing a positionetime trajectory of the wave front as it moves through the explosive sample.The data is used to determine the position and time for shock to detonation transition.All the experimental results show that the rising-up time of Al-based electromagnetic particle velocity gauge is very short(<20 ns);the reaction-build-up velocity profiles and the positionetime for shock to detonation transition of HMX-based plastic bonded explosive(PBX)JOB-9003 with 1e8 mm depth from the origin of the impact plane under different initiation pressures were obtained with high accuracy.

Capillary bridges and capillary forces between two axisymmetric power-law particles

Capillary interactions are fundamentally important in many scientific and industrial fields. However, most existing models of the capillary bridges and capillary forces between two solids with a mediated liquid, are based on extremely simple geometrical configurations, such as sphere-plate, sphere-sphere, and plate-plate. The capillary bridge and capillary force between two axisymmetric power-law profile particles with a mediated constant-volume liquid are investigated in this study. A dimensionless method is adopted to calculate the capillary bridge shape between two power-law profile particles based on the Young-Laplace equation. The critical rupture criterion of the liquid bridge is shown in four forms that produce consistent results. It was found that the dimensionless rupture distance changes little when the shape index is larger than 2. The results show that the power-law index has a significant influence on the capillary force between two power-law particles. This is directly attributed to the different shape profiles of power-law particles with different indices. Effects of various other parameters such as ratio of the particle equivalent radii, liquid contact angle, liquid volume, and interparticle distance on the capillary force between two power-law particles are also examined.

Particle image velocimetry measurement of velocity distribution at inlet duct of waterjet self-propelled ship model

A vehicle-mounted three-dimensional underwater particle image velocimetry（PIV） device is used in a towing tank to measure the velocity distribution of the inlet duct of a waterjet ship model in a self-propulsion test. The following points are shown through a comparison of the influences of the stationary and free states of the ship model on the measured results：（1） during the test, the ship attitude will change, specifically, the ship model will heave and trim,（2） the degree of freedom disturbs the processing of the pixel images enough to distort the subsequent image processing,（3） the stationary state of the ship model is the optimal mode for measuring the velocity distribution using the PIV device, and（4） if the changes must be considered, the man-made heaving and trimming may be pre-applied, and be made a corrected stationary mode. In addition, the momentum effect coefficient and the energy effect coefficient are calculated in a non-uniform inflowing state, and the related factors affecting the two coefficients are analyzed. The test results show that the pumping action of the waterjet creates a transverse vector in the cross-sectional speed, which increases the non-uniformity of the inflow. These results could help to establish the design requirements for a waterjet-propelled ship type.