600年,在颤悠中屹立——闽西客家土楼之精华:南靖下坂村"东倒西歪"楼

田螺坑下行4km就到了下坂村，村里十二座土楼井然有序地排列在南溪河两岸，我要看的“东倒西歪“楼就在这个村里，学名叫裕昌楼。从外面看，它和正常土楼没什么区别，可是当你踏入它的大门，你就会猛然发现全楼的回廊支撑木立柱左歪右倒，最大的倾角达到了150，似乎稍有大风它就会轰然倒塌。     

Heat transfer from immersed vertical tube in a fluidized bed of group A particles near the transition to the turbulent fluidization flow regime

Experiments were performed in a 0.29 m ID fluidization column to investigate heat transfer from a vertical tube immersed in a bed of 70 μm FCC particles in the range of superficial velocities close to the transition to the turbulent fluidization regime. The results show that the transition is a gradual process and that the changing hydrodynamics affect the heat transfer. The highest heat transfer coefficients were found in the range of superficial gas velocities where the transition to turbulent regime occurred. Radial profiles of heat transfer coefficient were almost flat in the turbulent fluidization regime and changed very little with increasing superficial gas velocity.     

Characterization of gas fluidized beds of group C,A and B particles based on pressure fluctuations

Pressure fluctuation data were obtained with a quick response transducer at a sampling frequency of 100 Hz for periods of 100 s (i.e. 10,000 points) in order to characterize the gas-solid flow behaviour of fluidized beds of six powders. For beds of Geldart group B and group A particles, the occurrence and movement of bubbles caused vigourous pressure fluctuations of relatively large scale and weak dominant frequency. For beds of group C particles, on the other hand, pressure fluctuations were significantly smaller in scale and exhibited large dominant frequencies, with no clear formation of bubbles. The standard deviation of pressure fluctuations was markedly higher for the group A particles than for the group C powders. Group C particles could be characterized by gas voids and channels which exhibit periodic behavior, while beds of group A and B particles behaved in a less periodic manner and were dominated by more random and intensive bubble motion. Chaotic time series analysis was carried out for the six different species of particles. The Hurst exponent demonstrated differences between the three different powder groups. The two-phase character of gas-solids flow was more distinguishable for the group B and A powders than for the group C powders.     

A MODEL TO EXPLAIN COMPOSITION EFFECTS IN SMELT-WATER EXPLOSIONS

A salt bridge model, which takes into account mass transfer of components between the two fluids, was developed and proved successful in interpreting the effects of composition on explosiveness in the smelt-water system. The model is based on the fact that the main smelt constituent, sodium carbonate, is not soluble in water at temperatures approaching the critical point, while certain other constituents are soluble. The soluble substances allow a substantial increase in the critical temperature of the solution, which in turn shifts the range of contact interface temperatures at which spontaneous explosions can occur (between the spontaneous nucleation temperature and the critical temperature of the coolant) to higher values. The model was able to provide an explanation of why sodium chloride, sodium hydroxide, and sodium sulfide act as smelt sensitizers and a semiquantitative definition of the concentration ranges in smelt and in the quench solution where spontaneous explosions are likely     

Comparison of decoupling methods for analyzing pressure fluctuations in gas‐fluidized beds

Two methods of decoupling pressure fluctuations in fluidized beds by using the incoherent part (IOP) of absolute pressure (AP) and differential pressure (DP) fluctuations are evaluated in this study. Analysis is conducted first to demonstrate their similarities, differences, and drawbacks. Then, amplitudes, power spectral densities, mean frequencies, coherence functions, and filtering indices of the IOP of AP and DP fluctuations are calculated and compared based on experimental data from a two‐dimensional fluidized column of FCC particles. Derived bubble sizes are also compared with the sizes of bubbles viewed in the two‐dimensional bed. The results demonstrate the similarity of these two methods in filtering out global compression wave components from absolute pressure fluctuations, especially those generated from oscillations of fluidized particles and gas flow rate fluctuations. However, both methods are imperfect. Neither can filter out all the compression wave components and retain all the useful bubble‐related wave components. Their amplitudes can be used to characterize global bubble property and quality of gas–solids contacting in bed, but they do not give accurate measurement of bubble sizes. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

Enhanced adsorptive removal of fluoride using mesoporous alumina

Two different kinds of mesoporous alumina samples were prepared using aluminum tri-sec-butoxide in the presence of either cetyltrimethylammonium bromide (MA-1) or stearic acid (MA-2) as a structure-directing agent, and tested for adsorptive removal of fluoride in water. Both materials contain a wormhole-like mesopore structure, but exhibited different textural properties: surface area (421 or 650 m²/g) and pore volume (0.96 or 0.59 cm³/g). These mesoporous aluminas demonstrated significantly improved adsorption capacity and faster kinetics to those of the commercial activated aluminas in fluoride removal by adsorption process. MA-2 prepared using stearic acid, in particular, demonstrated an adsorption capacity (14.26 mg/g) and initial adsorption rate (14.6 mg/g min) that were respectively 2.2 and 45 times higher than those of a commercial gamma alumina. The textural features of larger surface area and relatively smaller pore size in MA-2 compared to the activated aluminas are believed to be responsible for this enhancement in adsorption process.     

Some compositional changes in malted sorghum (Sorghum vulgare) grain and its value in broiler chicken diet

Grains of two sorghum (Sorghum vulgare L) varieties were germinated at room temperature for 2, 4 and 6 days. Germination resulted in an increase in protein content due to dry matter loss; this rose with increasing time of germination. The absolute amount of tannin was unchanged until the fourth day of germination but decreased markedly by the sixth day. Fractionation of the grain protein of one variety showed that there was a large increase in the albumin-globulin fraction (rich in lysine) and a decrease in the kafirin and cross-linked kafirin fraction (low in lysine) as a result of germination. Although these changes resulted in a more than 30% increase in lysine content on the fourth and sixth days of germination, a substantial loss in dry matter occurred when germination was continued up to 6 days. When 14-day-old Hubbard chicks were fed a diet containing about 59% malted sorghum supplemented with lysine, they showed better (P < 0.05) weight gain and efficiency of feed conversion than those on malted sorghum without lysine supplementation. However, malting reduced the amount of lysine needed to supplement the diet from 0.25% for unmalted sorghum to 0.18% for malted sorghum.