基于图像法的谷物流动特性测试分析

图像法是一种基于图像处理技术的非接触式测试手段,随着计算机技术与图像处理技术的发展,图像法被广泛应用于各个领域的测试工作中。通过对图像法测试技术的研究和对谷物在垂直管道中流动状态的观察与分析,提出了一种利用图像法测量谷物流动特性的新方法,并对所测得的信号进行统计及频谱分析,得到了谷物在垂直管道中流动时的一些特性,为谷物气力输送机械的设计与优化提供了参考依据。

混流干燥机中谷物二维流场的模拟

根据散粒体力学原理,建立了混流干燥机内谷物二维流动的数学模型;设计了“气泡显示法”对主应力方向进行下测定,建立了主应力方向同流线方向的近似关系式,从而实现了数学模型的简化。针对数学模型的特点,建立了沿流线求解的差分格式及其求解方法。对模拟方法进行了实验验证,模拟结果用实验结果基本一致。本模拟方法可用于研究混流干燥机内谷物流动的一般规律,也可用于谷物干燥的模拟模型。

The Ejffect of Vertical Internal Baffles on Fluidization Hydrodynamics and Grain Drying Characteristics

The effect of vertical internal baffles on the particle mixing and graindrying characteristics in a batch fluidized bed column is investigated. Experimental work wascarried out in a 3m high rectangular fluidized bed dryer of cross sectional area of 0.15 m x 0.61 mat different operating conditions using paddy, a group D particle, as the fluidizing material. Theresults of the study showed that the fluidized bed dryer system with vertical internal baffles gavebetter particle mixing effect in the bed of particles than that without vertical internal baffles.This is due to the fact that the vertical internal baffle act as gas bubble breakers by breaking upthe large gas bubbles into smaller ones. The smaller bubbles cause a more vigorous mixing in the bedof particles before finally erupting at the bed surface. This improves the contacting efficiencyand enhanced the heat and mass transfer of the fluidized bed system. Thus a higher drying rate wasobtained in the falling rate period because the higher contacting efficiency increases theevaporation rate at the particle surface. However, the drying rate in the diffusion region showslittle improvement because the moisture diffusivity does not depend on the contacting efficiency.The fluidized bed dryer with vertical internal baffles could therefore be used in the initial rapiddrying stage in a two stage drying strategy for paddy. The insertion of vertical internal bafflesinto a fluidized bed system improves the processing of Group D particles in a fluidized bed systemespecially if the system is large in scale.

Drug-induced liver injury in hospitalized patients with notably elevated alanine aminotransferase

AIM： To identify the proportion, causes and the nature of drug-induced liver injury （DILI） in patients with no- tably elevated alanine aminotransferase （ALT）. METHODS： All the inpatients with ALT levels above 10 times upper limit of normal range （ULN） were ret- rospectively identified from a computerized clinical laboratory database at our hospital covering a 12-mo period. Relevant clinical information was obtained from medical records. Alternative causes of ALT eleva- tions were examined for each patient, including bili- ary abnormality, viral hepatitis, hemodynamic injury, malignancy, DILI or undetermined and other causes. All suspected DILI cases were causality assessed usingthe Council for International Organizations of Medical Sciences scale, and only the cases classified as highly probable, probable, or possible were diagnosed as DILI. Comments related to the diagnosis of DILI in the medical record and in the discharge letter for each case were also examined to evaluate DILI detection by the treating doctors. RESULTS： A total of 129 cases with ALT 〉 i0 ULN were identified. Hemodynamic injury （n = 46, 35.7%）, DILl （n = 25, 19.4%） and malignancy （n = 21, 16.3%） were the top three causes of liver injury. Peak ALT val- ues were lower in DILI patients than in patients with hemodynamic injury （14.5 5.6 ULN vs 32.5 ：I： 30.7 ULN, P = 0.001）. Among DILI patients, one （4%） case was classified as definite, 19 （76%） cases were clas- sified as probable and 5 （20%） as possible according to the ClOMS scale. A hepatocellular pattern was ob- served in 23 （92%） cases and mixed in 2 （8%）. The extent of severity of liver injury was mild in 21 （84%） patients and moderate in 4 （16%）. Before discharge, 10 （40%） patients were recovered and the other 15 （60%） were improved. The improved patients tended to have a higher peak ALT （808 ＋ 348 U/L vs 623 ＋ 118 U/L, P = 0.016） and shorter treatment duration before discharge （8 ＋ 6 d vs 28 ~ 12 d, P = 0.008） compared with the recovered patients. Twenty-two drugs and 6 herbs were found associated with DILl. Antibacterials were the most common agents causing DILI in 8 （32%） cases, followed by glucocorticoids in 6 （24%） cases. Twenty-four （96%） cases received treatment of DILl with at least one adjunctive drug. Agents for treatment of DILI included anti-inflammatory drugs （e.g., glycyr- rhizinate）, antioxidants （e.g., glutathione, ademetionine 1,4-butanedisulfonate and tiopronin）, polyene phospha- tidyl choline and herbal extracts （e.g., protoporphyrin disodium and silymarin）. Diagnosis of DILl was not mentioned in the discharge letter in 60% of the cases. Relative to prevalent cases and cases from wards of internal medicine, incident cases and cases from surgi- cal wards had a higher risk of missed diagnosis in dis- charge letter [odds ratio （OR） 32.7, 95%CI （2.8-374.1）,CONCLUSION： DILI is mostly caused by use of anti- bacterials and glucocorticoids, and constitutes about one fifth of hospitalized patients with ALT 〉 10 ULN. DILI is underdiagnosed frequently.

Global virtual-land flow and saving through international cereal trade

With intense urbanization and sustained population growth, securing food production with limited land sources has increasingly become a pressing issue. Based on an analysis of international cereal(i.e., barley, buckwheat, maize, oats, rice, rye, sorghum, soybean, and wheat) trade and differences in yields of the cereal between export and import countries over the period of 2007 to 2011, we explore the great potential of land saving through the international cereal trade. By ‘land saving', we refer to the reduced global total of lands required to produce a necessary amount of cereal when cereal is exported from a country with relatively large yield of the cereal to a country with relatively small yield of the cereal. Our scenario analysis suggests that international cereal trade would help mitigate the shortage of domestic arable land for many island countries(e.g., Japan) and countries in the arid Middle East and North Africa(e.g., Syria and Morocco). Furthermore, international cereal trade has the potential to generate ‘land saving' of 50,092,284 ha of land per year, which is roughly the size of Spain. Drawing upon the definition of a similar concept – virtual water(Hoekstra and Hung 2002), we define virtual land as the area of land resources used for the production of goods. Through introducing the concept of virtual land, we believe land resources that are traditionally considered as stationary resources can flow with anthropogenic socioeconomic activities. The largest virtual-land flows(> 3,000,000 ha/year) exist between the United States(US) to China, Brazil to China, the US to Japan, the US to Mexico, and Argentina to China. However, not all virtual-land flows necessarily result in land saving. Thus, more endeavors are needed to plan the virtual-land flows for a larger land saving at the global scale.

Mechanical properties of nanocrystalline nanoporous gold complicated by variation of grain and ligament: A molecular dynamics simulation

A series of large-scale molecular dynamics(MD) simulations has been performed to study the effects of grain size and ligament diameter on the mechanical properties of nanocrystalline nanoporous gold. Such simulations indicate that the principal deformation mechanism is a combination of grain boundary sliding, grain rotation and dislocation movement. The results of uniaxial tensile tests reveal the presence of a reverse Hall-Petch relation between strength and nominal grain size, rather than the conventional Hall-Petch relationship in the present range of nominal grain size(7.9–52.7 nm). An increase of flow stress may possibly attribute to the lower total proportion of grain boundary sliding and grain rotation in the deformation of samples with larger grain size. The Young's modulus shows a linear relation with the reciprocal of nominal grain size, which depends largely on the volume fraction of grain boundaries and thus decreasing grain size leads to relatively lower Young's modulus. MD simulations on samples with ligament diameter ranging from 4.07 to 8.10 nm are also carried out and results show that the increasing ligament diameter resulted in decreased flow stress and increased Young's modulus.