Bayesian np control charts with adaptive sample size for finite production runs

The design of a control chart requires the specification of three decision variables, namely the sample size, n, the sampling interval, h, and the action limit under which the process must be stopped for potential repair. In this paper, the Bayesian attribute control chart, namely the np chart for short run production, using a variable sample size is discussed. In a simulated experiment, optimal solutions of the static np chart, the basic Bayesian np chart, and the Bayesian scheme with adaptive sample size are presented. Results of the empirical study show that varying the sample size leads to more cost savings compared with the other two approaches. In order to detect how the input parameters affect decision variables, a regression analysis is conducted. It is obtained that the benefits of using the basic Bayesian np chart and the Bayesian chart with adaptive sample size instead of the static scheme are affected by the length of the production run. Copyright © 2008 John Wiley & Sons, Ltd.     

Changes in Lipid Composition and Antioxidant Capacity of Bitter Orange (<Emphasis Type="Italic">Citrus aurantium.</Emphasis> L) and Mandarin (<Emphasis Type="Italic">Citrus reticulata.</Emphasis> Blanco) Oilseeds on Different Stages of Maturity

Oilseeds from bitter orange and mandarin and its antioxidant activities were investigated in this study. The effects of harvesting times (D1: green color, D2 yellow color, D3: orange color) on the extraction yield of oilseed were studied. The maximum yield of 44% was achieved at D3 (bitter orange). The chemical composition of the oilseed was analyzed by gas chromatography (GC). The main methyl esters were linoleic acid (C18:2, 32–42%), palmitic acid (C16:0, 22–26%)), stearic acid (C18:0, 9.01%) and linolenic acid (C18:3, 4–10%). The antioxidant activity of oilseed was assessed by means of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay and β-carotene bleaching test. Both methods demonstrated notable antioxidant activities of bitter orange and mandarin oilseeds, which is nearly comparable to the references ascorbic acid and butylated hydroxytoluene (BHT). The antioxidant activities of the oilseeds were also found to be harvesting time-dependent.     

Total Phenolics, Flavonoids, and Antioxidant Activity of Sage (Salvia officinalis L.) Plants as Affected by Different Drying Methods

In the current study, we determined the effects of seven drying methods on total phenolics, flavonoids, individual phenolics, and antioxidant activity of the methanol extract of Salvia officinalis L. As compared with total phenolic content (TPC) of fresh plants, results showed that the highest TPC was recorded in plants dried by microwave (MW) at a power of 800 W/30 g of fresh plant and was 4.2 times higher than that of fresh plants whereas the lowest content was found in the case of plants dried by far-infrared (FIR) at 45 °C. The analysis of the different extracts by RP-HPLC showed a predominance of phenolic acids particularly in fresh plants and those dried by MW (600 W/30 g of fresh plant) whereas flavonoids predominate in the case of plants dried by FIR (65 °C). The assessment of the radical scavenging activity (RSA) against the stable radical 1,1-diphenyl-1-picrylhydrazyl (DPPH) showed an increase in the scavenging effect particularly in MW (800 W/30 g of fresh plant) dried plants with an IC50?=?13.49 μg ml^?1 (IC50 is the concentration required to cause 50 % DPPH inhibition). The complementary assessment of the RSA using the β-carotene/linoleic acid system showed an increase of this activity for all extracts and particularly for the extract derived from MW (600 W/30 g of fresh plant) dried plants as compared to fresh ones. Finally, all the plant extracts showed moderate reducing power as assessed by the ferric-reducing antioxidant potential. These results suggested that MW drying could be applied to retain phenolic contents and to enhance antioxidant activity of sage plant materials.     

RC beams strengthened with composite material: a limit analysis approach and experimental study

This paper deals with the flexural strengthening of reinforced concrete beams by means of thin carbon fibre reinforced plastic (CFRP) plates. A simplified laminated plate model is used to describe the behaviour of three-layered plate in cylindrical bending which were subjected to third-point line loads. The upper bound theorem of limit analysis is used to approximate the ultimate load capacity for multi-layered plates and identify different collapse mechanisms. A reinforced concrete beam strengthened by CFRP is designed as a three-layered plate. Experimental results are obtained and a comparison with theoretical predictions made.     

Experimental collapse of thin cylindrical shells submitted to internal pressure and pure bending

A thin-walled pressurised cylindrical shell is sensitive to buckling phenomena when it experiences locally a compressive stress. It is often considered that its behaviour under bending is rather similar to pure compression, but very few are the experimental investigations that precise the real behaviour of a thin pressurised cylinder submitted to a bending load. A large amount of experimental results is presented here, obtained on thin shells (550<R/t<1450) of moderate length (L/R≈2). The evolution of the cylinders' behaviour that has been recorded when internal pressure increases is outlined. It is shown that one must distinguish between local buckling and global collapse of the structure. A comparison of our experimental data to design recommendations given by two standards (NASA SP8007 and Eurocode 3) is finally achieved, putting in advance safety margins provided by these codes.     

Effects of openings of the buckling of cylindrical shells subjected to axial compression

Experimental and numerical methods are used to study the stability problem of cylindrical shells with cut-outs. The paper presents parametric research of the shape (square, rectangular, circular), the dimensions (axial and circumferential sizes, diameter) of the hole. The effect of the location and the number of the holes are also studied. The analysis indicates that the critical load is sensitive to the opening angle or circumferential size of the hole. The function (critical load-opening angle) is linear for large openings and independent of the geometrical imperfections of the shell. However for small openings, it is necessary to take into account the coupling between the initial geometrical imperfections and the openings. The linear approach does not fit because of the importance of the evolution of the displacements near the openings. These results will be used for the development of European rules.     

Study and characterization by acoustic emission and electrochemical measurements of concrete deterioration caused by reinforcement steel corrosion

The durability of reinforced concrete structures becomes a matter of concern, due primarily to the increase of damage by the corrosion of steel reinforcements. This corrosion is not only related to the composition and to the procedure of concrete manufacturing (water/cement, sand/cement, etc.), but also to the aggressive agents as chlorides, carbon dioxide, etc. present in the surrounding medium (Cl⁻, CO₂, etc.). It is well known that the first kind of rebar corrosion (chloride) is more detrimental and that this process contains three basic components: chloride diffusion, electrochemical corrosion and concrete fracture. Therefore the early detection of possible degradation of structures by means of non-destructive testing is essential in order to ensure the functionality of these structures.

This paper presents the results of an experimental investigation on the use of acoustic emission during the corrosion of steel rebars embedded in mortar and immersed in sodium chloride solution. The process of corrosion is accelerated by various imposed potentials and is followed by acoustic emission coupled to electrochemical techniques. The experimental results show that electrochemical techniques can evaluate the corrosive character of the medium used. The acoustic emission showed an activity characteristic of the corrosion initiation phase and the corrosion propagation phase. Thus, it was significantly possible to highlight the acoustic signature of the concrete damage related to the porosity of the mortar and to chloride concentration. The results also show a perfect correlation between the evolution of the acoustic activity and the current of corrosion density.     

Qualitative and quantitative changes in the essential oil of Laurus nobilis L. leaves as affected by different drying methods

The effect of six different drying methods on the content and chemical composition of the essential oil of Laurus nobilis L. leaves was studied. The essential oils from fresh and dried samples were isolated by hydrodistillation in a Clevenger apparatus and analysed by gas chromatography–mass spectrometry (GC–MS). Results showed that air drying at ambient temperature and infrared drying at 45 °C increased significantly the essential oil content. Forty-seven components were determined in essential oils, which were mostly oxygenated monoterpenes. This class of compounds is not significantly affected by the method of drying except for air drying at ambient temperature. The main components 1,8-cineole, methyl eugenol, terpinen-4-ol, linalool and eugenol showed significant variations with drying methods. The concentrations of these compounds increased significantly in the case of air drying at ambient temperature. These results allowed considering this method of drying as the method that produced the best results in terms of essential oil and bioactive compounds contents.