The influence of ripening and crop year on quality indices,polyphenols, terpenic acids,squalene, fatty acid profile,and sterols in virgin olive oil (Koroneiki cv.) produced by organic versus non‐organic cultivation method

The chemical composition of virgin olive oil is determined by numerous factors. The aim of this study was to evaluate the influence of the olive ripening stage, and crop year on the quality indices of Koroneiki cv. virgin olive oil of organic vs non‐organic cultivation. Drupes of organic and of non‐organic cultivation were sampled at four successive ripening periods in crop years 2000 and 2004. Quality indices, total and simple polyphenols, terpenic acids, squalene, fatty acid profile, and sterols were measured. Statistical analysis demonstrated that peroxide value differed according to cultivation method and according to crop year. Organic Koroneiki cv. olive oils exhibited higher total phenols content. Total phenols differed mainly according to crop year and maturation phase, but also according to cultivation method. Total unsaturated and saturated fatty acids differed according to cultivation method, crop year and maturation. Oleic and palmitoleic acids varied according to cultivation method and according to maturation process. Cholesterol, campesterol and stigmasterol differed according to maturity, while β‐sitosterol differed according to crop year. Overall, olive oil from organic cultivation was of superior quality compared to non‐organic, while composition of olive oils was greatly variable during maturation, whereas it was also affected by the crop year.     

A reinterpretation of the Odar and Hamilton data on the unsteady equation of motion of particles

The experimental data and correlations derived by Odar and Hamilton have been the basis of studies that included the history term in the expression of the unsteady drag. Recent studies have shown that the value of the added mass coefficient is constant and equal to ½ over a very large range of Reynolds numbers. Recent studies on the history term have proven that its form is not correct at high Re. However, the experimental data are accurate at low Re and, most probably, they represent the most reliable set of experimental data on the unsteady force on solid spheres. We conducted a study to re‐calculate the functional form of the history term in the unsteady equation of motion at low Re and to derive a new correlation for the so‐called “history force coefficient,” Δ_H. The new correlation is expressed in terms of the Reynolds and Strouhal numbers of the particle. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Thermal/structural analysis of radiators for heavy-duty trucks

A thermal/structural coupling approach is applied to analyze thermal performance and predict the thermal stress of a radiator for heavy-duty transportation cooling systems. Bench test and field test data show that non-uniform temperature gradient and dynamic pressure loads may induce large thermal stress on the radiator. A finite element analysis (FEA) tool is used to predict the strains and displacement of radiator based on the solid wall temperature, wall-based fluid film heat transfer coefficient and pressure drop. These are obtained from a computational fluid dynamics (CFD) simulation. A 3D simulation of turbulent flow and coupled heat transfer between the working fluids poses a major difficulty because the range of length scales involved in heavy-duty radiators varies from few millimeters of the fin pitch and/or tube cross-section to several meters for the overall size of the radiator. It is very computational expensive, if not impossible, to directly simulate the turbulent heat transfer between fins and the thermal boundary layer in each tube. In order to overcome the computational difficulties, a dual porous zone (DPZ) method is applied, in which fins in the air side and turbulators in the water side are treated as porous region. The parameters involved in the DPZ method are tuned based on experimental data in prior. A distinguished advantage of the porous medium method is its effectiveness of modeling wide-range characteristic scale problems. A parametric study of the impact of flow rate on the heat transfer coefficient is presented. The FEA results predict the maximum value of stress/strain and target locations for possible structural failure and the results obtained are consistent with experimental observations. The results demonstrate that the coupling thermal/structural analysis is a powerful tool applied to heavy-duty cooling product design to improve the radiator thermal performance, durability and reliability under rigid working environment.     

Quality Characteristics and Antioxidants of Mavrolia cv. Virgin Olive Oil

The quality characteristics and bioactive microconstituents of virgin olive oil produced by Mavrolia cv, an Olea europaea variety grown in Southern Peloponnesus, Greece, are reported for the first time. The oil samples of Mavrolia cv. studied fell within the limits established for the extra virgin olive oil (EVOO) category and were characterized by higher levels of campesterol (88.7 ± 14.8 vs. 56.1 ± 6.1 mg kg⁻¹ oil) and β-sitosterol (1692.6 ± 100.3 vs. 1356.2 ± 85 mg kg⁻¹ oil) and relatively lower oxidative stability (19.35 ± 2.62 vs. 37.44 ± 1.97 h) compared to Koroneiki cv. The lower oxidative stability was positively correlated to significantly lower polyphenols (88.95 ± 2.33 vs. 233.75 ± 34.29) and α-tocopherol (517.2 ± 6.50 vs. 655.37 ± 17.78) and to higher polyunsaturated fatty acids content (9.27 ± 0.35 vs. 6.41 ± 0.38). Tyrosol, ferulic acid and protocatechuic acid contents were significantly higher in Mavrolia cv. samples compared to Koroneiki cv. (218.80 ± 44.8 vs. 83.7 ± 23.1, 1.82 ± 0.11 vs. 0.97 ± 0.31, and 1.55 ± 0.39 vs. 0.35 ± 0.60 mg kg⁻¹, respectively). Also, the bitter and pungent attributes were found in lower intensities compared to Koroneiki cv. EVOO for the same period (1.9 vs. 2.5 and 2.3 vs. 3.9, respectively). The ripe fruity intensity with walnut olfactory attribute of the Mavrolia cv., was also light to medium.     

Effects of the variation of mass loading and particle density in gas-solid particle flow in pipes

The method of two dimensional Reynolds Averaged Navier-Stokes (RANS) equations has been employed for the simulation of turbulent particulate flow. This approach was fitted with appropriate closure equations that take into account all the pertinent forces and effects on the solid particles, such as: particle-turbulence interactions; turbulence modulation; particle-particle interactions; particle-wall interactions; gravitation, viscous drag and lift forces. The flow domain in all cases was a cylindrical pipe and the computations were carried for upward pipe flow. The finite volume technique was used for the numerical solution of the governing and closure equations. The results show the effect of loading and particle density on the profiles of the velocity, the turbulence intensity and the solids concentration.     

Bonded Cracked Half Planes with an Interface and an Interesting Crack

The solution of the plane elasticity problem of two bonded isotropic linearly elastic half-planes of different elastic properties having a crack L along the interface as well as a crack S in one of the half planes which intersects the interface crack, is given by using the Muskhelishvili's complex variable method with sectionally holomorphic functions. The initial problem is reduced to a Hilbert problem, the solution of which in the case of a dislocation existing in either half-planes constitutes the Green's functions of the problem. Finally, a singular integral equation is derived for the problem only along the crack S. The singular integral equation is solved numerically and results are presented for the stress intensity factors. This revised version was published online in July 2006 with corrections to the Cover Date.     

Dechlorinating ability of TCE-fed microcosms with different electron donors

The main objective of the work presented herein is to assess the effect of different electron donors (butyric acid and methanol) on the dechlorinating activity of two microbial cultures where active methanogenic populations are present, in an effort to evaluate the importance of the electron donor selection process. The ability of each anaerobic culture to dechlorinate TCE, when enriched with either butyric acid or methanol, was verified based on the results of gas chromatography. In addition, the fluorescent in situ hybridization (FISH) and the polymerase chain reaction (PCR) methods gave positive results for the presence of Dehalococcoides spp. According to results of the batch tests conducted in this study, it appears that the selection of the electron donor for stimulating TCE dechlorination depends on microbial culture composition; therefore, the decision on the appropriate electron donor should be based on site-specific microcosm studies.     

Building a signaling protocol architecture for future mobile networks

Third-generation mobile systems are emerging. These systems will support a unified user access to a variety of services, including the existing mobile and fixed network (PSTN, N-ISDN) services, the enhanced multimedia and multiparty services envisaged for broadband networks, and personal communication services as well. The role of signaling is predominant in building a flexible, efficient, and evolving system. The aim of this paper is to provide a framework for developing a signaling protocol architecture for future mobile networks. The study especially focuses on the universal mobile telecommunication system (UMTS). Within this framework various design and operational requirements imposed on UMTS can be satisfied. A method to deal with the functional complexity of UMTS is provided. Mobile networks are viewed as integral parts of the broadband infrastructure and are built upon the IN principles.     

PRESSURE CHANGES AT A SUDDEN EXPANSION IN GAS-SOLID FLOWS

There is a pressure recovery when a two-phase mixture passes through a pipe enlargement. This paper describes an experimental project for the determination of this pressure recovery in air-solids systems. The solids used are medium size wax and lucite particles. Two pipe diameter ratios were investigated, 0.63 and 0.76. The Reynolds numbers for the experiments varied between 45000 and 72000 and the loading ratios were low to intermediate (up to 6), it was observed that the major part of the pressure recovery in these mixtures was due to the air alone and that only a small part of it (up to 25%) was due to the deceleration of solid particles.