Multiobjective hierarchical control architecture for greenhouse crop growth

The problem of determining the trajectories to control greenhouse crop growth has traditionally been solved by using constrained optimization or applying artificial intelligence techniques. The economic profit has been used as the main criterion in most research on optimization to obtain adequate climatic control setpoints for the crop growth. This paper addresses the problem of greenhouse crop growth through a hierarchical control architecture governed by a high-level multiobjective optimization approach, where the solution to this problem is to find reference trajectories for diurnal and nocturnal temperatures (climate-related setpoints) and electrical conductivity (fertirrigation-related setpoints). The objectives are to maximize profit, fruit quality, and water-use efficiency, these being currently fostered by international rules. Illustrative results selected from those obtained in an industrial greenhouse during the last eight years are shown and described.     

胶黏钢-混凝土组合梁的界面行为数值分析

根据推出的试验测试数据,将黏胶/混凝土界面的剪切-滑移行为用具备损伤本构关系的弹簧单元来模拟,建立胶黏钢-混凝土组合梁的三维非线性有限元模型.基于模拟结果,揭示了组合梁黏胶/混凝土界面的黏结应力分布规律及脱胶剥离过程.分析结果表明:弹性模量小的黏胶剂更有利于界面的剪力均匀传递,但会引起混凝土板和钢梁间产生大的相对滑动,导致结构整体承载力降低.胶黏组合梁的界面脱胶剥离是一个突发的典型脆性破坏过程,会产生灾难性后果,在设计过程中需引起足够重视.     

Determination of Aldehydes in Environmental Water by Solid-Phase Microextraction and Gas Chromatography - Ion Trap Mass Spectrometry

Microwave-assisted extraction coupled to headspace solid-phase microextraction with on-fiber derivatization with gas chromatography ion trap mass spectrometry analysis is reported for the determination of aldehydes in environmental water. Hexanal, (E)-2-hexenal, heptanal, octanal, nonanal, E-2-decanal, and E, E-2,4-decadienal were employed to develop and validate this method. The effects of relevant parameters on the quantitative extraction of these analytes in this one-step procedure were systematically investigated. The aldehydes were extracted from environmental water by a poly(dimethylsiloxane)/divinylbenzene fiber using o-(2, 3, 4, 5, 6-pentafluoro)-benzylhydroxylamine as the derivatization reagent. Under microwave-assisted heating, the aldehydes were transferred from water by headspace solid phase microextraction. Thus, efficient extraction and derivatization were simultaneously achieved. The recovery values ranged from 72.2–96.9%, and the relative standard deviation was between 4.1–14% for the aldehydes. The detection limits were from 0.001–0.005 µg L^?1. The method was validated illustrating its potential for the analysis of environmental water while offering simplicity and rapid analysis.     

In-situ oxidation of crude oils for enhanced recovery by alkaline flooding

Crude oils with acid numbers too low to warrant alkaline flooding for enhanced oil recovery were subjected to in-situ air oxidation in unconsolidated cores at temperatures corresponding to reservoir conditions. The oxidation process resulted in a significant increase in the acid number of the crudes studied. Acid numbers were found to increase with temperature, air flow rate, pressure, and reaction time and were found to be affected by the core and crude composition. The range of conditions studied include temperatures of 75–125 °C, pressures of 0.34–3.10 MPa [50–450 psig], reaction times of 24–504 h and core flow rates of 0–1.41 m h⁻¹ (0–111 ft day⁻¹). Oxidized crudes were found to have much lower caustic/crude interfacial tensions than the parent crude. Flooding experiments in unconsolidated cores showed an improved recovery efficiency for an oxidized crude over its parent crude.     

On the preparation of a monoclinic (nearly) single crystal of zeolite HZSM-5

HZSM-5 appears to be ferroelastic. Application of a uniaxial mechanical stress during the orthorhombic/monoclinic transition of zeoltie HZSM-5 changes the population of the monoclinic twin domains. The volume fraction of one of the twin mates is changed from 0.5 (before application of mechanical stress) to 0.06 in the crystal studied.     

Rheological behavior of cellulose nanocrystal suspension: Influence of concentration and aspect ratio

The steady and dynamic rheological behaviors of two cellulose nanocrystal (CNC) suspensions were investigated over a wide range of concentrations. The viscosity, storage and loss modules increased with increasing CNC concentration, and both CNC suspensions showed three regions in a viscosity‐concentration graph. The two critical concentrations depended on the aspect ratio and corresponded to the overlap and gelation concentration. Because of the higher aspect ratio, switchgrass CNC suspension transitioned into a biphasic state and formed a hydrogel at lower concentrations than those of cotton CNC suspensions. Furthermore, the complex viscosities of both CNC suspensions were higher than their steady viscosities; therefore, neither CNC suspension followed the Cox–Merz rule, which may be attributed to the existence of a liquid crystal domain in each suspension. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40525.     

Digestion and protein metabolism of Trogoderma granarium (Coleoptera: Dermestidae) fed on different barley varieties

The Khapra beetle, Trogoderma granarium Everts, is one of the most important pests of grains which rapidly infests durable stored products in hot and dry conditions. In the current study, effects of omit ten varieties of barley (Abidar, Bahman, Line20, Line22, Line30, Lisivi, Lokht11, Makuyi, Sahand and Sahraa) were determined on digestive enzymes and protein metabolsim of T. granarium larvae under laboratory conditions as 33 ± 1 °C, 65 ± 5% RH and photoperiod of 14:10 (L: D) h. The highest and the lowest activities of α-amylase were observed in T. granarium larvae fed on Line30 and Lisivi varieties, respectively but the glucosidases showed the highest activities followed by feeding on Lokht 11. Also, the latter variety caused the highest lipase activity in the larvae while Abidar, Line20, Lisuei and Sahand imposed the lowest lipase activity. The highest activities of serine proteases including trypsin, chymotrypsin and elastase were detected in the larvae fed on Line 30 but the two exopeptidases, amino- and carboxypeptidases, showed the highest activities when the larvae fed on Lisuei. All the three aminotransferses had the highest activities in the larvae fed on Lokht 11 as the related individuals contained the maximum amount of protein compared to other ones. Results of the current study highlighted Line30 as the most suitable variety to be digested by serine proteases and α-amylase but Lokht11 is appropriately digested by glucosidases and lipase which emboss their susceptibilities to T. granarium. Our findings on digestion and protein metabolism imply on susceptibility of varieties Line30 and Lokht11 to T. granarium larvae.