Reliability analysis of a mechanical contact between deformable solids

The contact problems in mechanics are very complex. The behavior of a structure, where a contact occurs, depends on some assumptions on the design parameters and is in general highly nonlinear. Several deterministic numerical methods have been developed on finite element codes and give accurate solutions of contact problems. However some design variables could be random and the deterministic results could be unacceptable. Thus a new reliability analysis of a mechanical contact is presented. A reliability–mechanical combination based on an augmented Lagrangian method and a response surface method is proposed to compute the failure probability of this nonlinear problem. Then the advantages of this probabilistic approach are exposed and commentated on an Hertz numerical application.     

油田开发时变结构预测模型的建立及应用

在油田开发规律研究的基础上，将预测模型中的待定系数确立为时变参数，建立了油田广义产量和两类常用水驱特征曲线的时变结构预测模型，并利用系统辨识理论中多层递阶预报方法进行参数估计，可大大提高模型的拟合精度和预报精度，经实际资料的应用，效果较好。     

Inactivation of peroxidase and lipoxygenase in carrots, green beans, and green peas by combination of high hydrostatic pressure and mild heat treatment

The efficiency of high hydrostatic pressure (HHP) with the combination of mild heat treatment on peroxidase (POD) and lipoxygenase (LOX) inactivation in carrots, green beans, and green peas was investigated. In the first part of the study, the samples were pressurized under 250–450 MPa at 20–50 °C for 15–60 min. In the second part, two steps treatments were performed as water blanching at 40–70 °C for 15 and 30 min after pressurization at 250 MPa and 20 °C for 15–60 min. Carrot POD was decreased to 16% residual activity within the first 30 min at a treatment condition of 350 MPa and 20 °C and then it decreased to 9% at 60 min. When the carrots were water blanched at 50 °C for 30 min after HHP treatment of 250 MPa at 20 °C for 15 min, 13% residual POD activity was obtained. For green beans, the most effective results were obtained by two steps treatment and approximately 25% residual POD activity was obtained by water blanching at 50 °C for 15 min after pressurization at 250 MPa and 20 °C for 60 min. An effective inactivation of POD in green peas was not obtained. For carrots, LOX activity could not be measured due to very low LOX activity or the presence of strong antioxidants such as carotenoids. After pressurization at 250 MPa and 20 °C for 15 or 30 min, water blanching at 60 °C for 30 min provided 2–3% residual LOX activity in green beans. The treatment of 250 MPa for 30 min and then water blanching at 50 °C for 30 min provided 70% LOX inactivation in green peas.     

Inactivation of Listeria monocytogenes and Escherichia coli by Ultrasonic Waves Under Pressure at Nonlethal (Manosonication) and Lethal Temperatures (Manothermosonication) in Acidic Fruit Juices

The inactivation of Listeria monocytogenes and Escherichia coli suspended in apple and orange juices by ultrasound under pressure at nonlethal (manosonication, MS) and lethal temperatures (manothermosonication, MTS) was evaluated. Significant differences were found in the MS resistance (35 °C, 110 μm, 200 kPa) of three strains of L. monocytogenes and three of E. coli in pH 3.5 buffer, L. monocytogenes STCC 5672 and E. coli O157:H7 being the most resistant strains. Regarding the interspecific differences, L. monocytogenes showed higher MS resistance than E. coli. Although the pH and treatment medium composition did not significantly change the bacterial MS resistance, the effectiveness of ultrasound increased by both raising the amplitude of ultrasonic waves and the pressure. The energy transmitted to the fruit juices by ultrasonic waves at different combinations of amplitudes (46.5, 90, 110, and 130.5 μm) and pressures (0, 100, and 200 kPa) was also studied, obtaining an exponential relationship between the D _MS values and power input: an increase of 116 W increased the inactivation rate approximately 10-fold in both juices. The MS resistance of both species decreased when heat was applied jointly with ultrasound (MTS), which was more effective in inactivating L. monocytogenes and E. coli than the sum of MS and heat acting simultaneously but independently. Therefore, MTS showed a synergistic lethal effect in acidic juices, whose magnitude was dependent on the treatment conditions.     

吐哈盆地北部山前带巴喀三维叠前地震成像处理解释技术研究及应用

吐哈盆地北部山前带巴喀地区地表条件复杂多样,地下构造复杂,导致该区原始地震资料品质较差,尤其是构造主体部位地层高陡,断裂非常发育,地震偏移成像难度极大,从而使得该区地下构造难以准确落实;同时巴喀地区储层为低孔低渗储层,地球物理响应特征不明显,缺乏有效的储层预测识别方法,以上因素制约了巴喀地区油气勘探的进程。通过研究,形成了针对巴喀地区的地震成像、构造解释及储层预测技术系列,其中的关键创新技术主要包括:起伏地表模型约束综合静校正技术、复杂地区"六分法"叠前噪声压制技术、浮动面逆时叠前深度偏移技术等。攻关与生产紧密结合,新研究成果能够更加准确地刻画巴喀地区的断裂位置及地下构造形态,整体成像效果得到改善,利用新研究成果重新梳理了构造样式,进一步认识了该区断裂特征及地层展布规律,新发现和落实了一批圈闭,在此基础上综合储层预测成果,优选了多个有利钻探目标。     

Deep channel operating characteristics of a single screw extruder: Finite element predictions and experimental results for isothermal non-Newtonian flow

Finite element solutions are presented for developed, isothermal, power-law flow in an extruder channel, based on a variational formulation in helical co-ordinates. The success of the method in handling non-Newtonian flow in a deep, highly-curved channel is tested by comparison with experimental results. Operating characteristics were determired under virtually isothermal conditions for a screw with depth to diameter ratio 0.25 pumping an aqueous glucose solution containing high molecular weight hydroxyethyl cellulose. Shear stress and first normal stress differences of this solution were determined in a rheogoniometer. It was both highly shear-thinning and elastic. Computed and experimental screw operating characteristics agree well, except near closed discharge, where effects due to viscous heating and elasticity are tentatively suggested.     

Multiobjective backtracking search algorithm: application to FSI

Fluid-structure interaction (FSI) problems play an important role in many technical applications, for instance, wind turbines, aircraft, injection systems, or pumps. Thus, the optimization of such kind of problems is of high practical importance. Optimization algorithms aim to find the best values for a system’s parameters under various conditions. In this paper, we present a new Backtracking Search Optimization Algorithm for multiobjective optimization, named BSAMO, a new evolutionary algorithm (EA) for solving real-valued numerical optimization problems. EAs are popular stochastic search algorithms that are widely used to solve nonlinear, nondifferentiable and complex numerical optimization problems. In order to test the performance of this algorithm, a well known benchmark multiobjective problem has been chosen from the literature, and for FSI optimization, using a partitioned coupling procedure. The method has been tested through a 2D plate and a 3D wing subjected to aerodynamic loads. The obtained Pareto solutions are then presented and compared to those of the Non-dominated Sorting Genetic Algorithm-II (NSGA-II). The numerical results demonstrate the efficiency of BSAMO and also its best performance in tackling real-world multiphysics problems.

     

Effect of High Hydrostatic Pressure (HHP) Treatment on Physicochemical Properties of Horse Mackerel (Trachurus trachurus)

The basic objective of this study was to determine the effect of high hydrostatic pressure (HHP; 220, 250 and 330 MPa), holding time (5 and 10 min) and temperature (7, 15 and 25 °C) on some quality parameters of horse mackerel such as colour changes, thiobarbituric acid (TBA-i) and trimethylamine nitrogen (TMA-N), free amino acid content. HHP increased L ^* values of horse mackerel. The a ^* and b ^* of treated horse mackerel did not change significantly after HHP applications. After, HHP, TBA-i and TMA values of all HHP-treated horse mackerel samples remained unchanged than those of untreated samples. The results obtained from this study showed that the quality of high pressure treated horse mackerel is best preserved at 250 MPa, 7–15 °C for 5 min, 220 MPa, 15–25 °C for 5 min, 250 MPa, 15 °C for 10 min and 330 MPa, 25 °C for 10 min.     

Effect of high pressure (HP) on the quality and shelf life of red mullet (Mullus surmelutus)

The effect of different temperature/time/pressure high hydrostatic pressure (HP) treatment on the quality and shelf life of red mullet were studied. Different high pressure treatments (at 3, 7, 15 and 25 °C, 5 to 10 min and 220, 250 and 330 MPa) were tested to establish the best processing conditions for the quality of red mullet. The effect of the process on the quality of the sample was examined by colour, Trimethylamine nitrogen (TMA-N) and Thiobarbituric acid number (TBA) analysis. Based on the results of the parameters, the best combinations of HP treatments were determined as 220 MPa/5 min/25 °C and 330 MPa/5 min/3 °C for red mullet. The effects of this combination treatment on sensory, chemical and microbiological properties of red mullet stored at 4 °C were studied. The results obtained from this study showed that the shelf life of untreated and HP treated stored at 4 °C, as determined by overall acceptability of sensory and microbiological data, are 12 days for untreated red mullet and 14 days for treated red mullet at 220 MPa for 5 min at 25 °C and 15 days for treated red mullet at 330 MPa for 5 min at 3 °C.Industrial relevanceFresh fish have short shelf life. HP treatment has shown to be an effective method to control pathogen and spoilage microorganisms in fish and fish products. However, high pressure treatment can promote colour and oxidation changes that could modify their sensory characteristics. The main objective of the first part of this study was to detect the best combination among the applied pressure (220, 250 and 330 MPa), temperature (3, 7, 15 and 25 °C) and time (5 and 10 min) combinations. The treatment ranges were chosen according to the unchanging colour, lower TBA value and TMA stability by HP and considering the economical aspects of HP processing. In the second part of the study, HP was applied on the selected samples and a shelf-life study was performed by measuring the changes in the quality parameters, of the samples throughout their storage. The storage conditions were set so as to achieve refrigeration handling (4 °C). Shelf-life estimation was performed according to the data obtained. HP (at 220 MPa for 5 min at 25 °C and at 330 MPa for 5 min at 3 °C) treatment is the most effective treatment for shelf-life extension as compared to non-treated red mullet.