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Abstract

In this work a multilevel Computational Fluid Dynamics (CFD) analysis has been applied for the design of a Formula race car exhaust muffler with improved characteristics of sound pressure level (SPL) and fluid dynamic response. The approaches developed and applied for the optimization process range from the 1D to fully 3D CFD simulation, exploring hybrid approaches based on the integration of a 1D model with 3D tools. Modern mufflers typically have a complex system of chambers and flow paths. There are a variety of sound damping and absorbing mechanisms working to quiet the sound flowing through a muffler and piping system. Two calculation methods were selected for this study. The muffler has a complex inner structure containing perforated pipe and fiber material. Computer-aided design (CAD) file of the muffler was established for developing Finite Element Analysis (FEA) model in AVL BOOST v2017 and another commercial advanced design software (SolidWorks 2017). FEA model was made to monitor the flow properties, pressure and velocity. After the model was verified, sensitivity studies of design parameters were performed to optimize the SPL of the muffler. The software analysis results are included in the paper. Recommendations are made for obtaining smoother SPL curves for various measurement methods.

Open access

Abstract

In this work, a numerical method is proposed in order to achieve design optimisation of phased array (PA) probes for the special application of defects detection in thin films. This approach relies on an extended Fourier-based model that was adapted to predict the two-dimensional ultrasonic displacement field taking place in a thin plate under individual excitation of PA probe elements which have arbitrary orientation with respect to the examined part surface. Excitation is applied through a fluid couplant and is operated at scheduled delays that are managed to enable emission of constructive pulses. This gives the possibility to steer sound waves towards a direction and to focalize the beam in a selected point. An optimisation algorithm based on the concept of pattern search that does not require evaluation of a gradient was used to find the best match in the multidimensional analysis space of possibilities including the elements orientation angles, the elements lengths, the inter-elements distances and work frequency. Optimisation was performed with the objective to maximize the displacement amplitude at the focal point while minimizing simultaneously the effect of beam side lobes. The results obtained by this approach reveal that focalisation can be achieved with enhanced features in comparison with previous algorithms assuming linear elements that are parallel to the surface of the plate.

Open access
International Review of Applied Sciences and Engineering
Authors: Norbert Novák, Péter Miklós Kőmíves, Mónika Harangi-Rákos and Károly Pető

Abstract

The role of rural areas partly changed in the last decades. The countryside is still functioning as the main food producer of the world and this role became much more important because of the global population growth and because of the change in dietary habits. But other rural functions appeared just like recreation, health preservation, and on the other hand the different ecological functions' importance increased. The population living in the countryside is continuously decreasing as more and more people try to move into urban areas. One of the main aims of this article is to give a brief literature overview on the services needed in the rural areas in order to stop migration from the countryside to the cities. Based on extensive literature review the article summarizes the changing functions of the countryside and tries to list those developments which are needed to preserve rural population.

Open access

Abstract

In the building mechatronics research centre of University of Debrecen, Faculty of Engineering, a new laboratory has been designed, named “Cyber-physical and intelligent robot systems laboratory”. The possibility to design and test unique and platform-independent systems was among the main goals, hoping that the system itself and its advancements may later be used in manufacturing industries as well.

Fulfilling the needs of “Industry 4.0” is a challenging task, as it requires every single device (e.g. industrial robots) to be connected to the same network, where they may be monitored and controlled. However, there are some factors that limit this, such as the periodical “instability” that some machines have, caused by singularity points.

The following material studies these so-called singularities of a KUKA KR5 industrial welder robot placed in a robot cell, from an engineering viewpoint.

Open access

This study was conducted to assess the effects of 2,4-epibrassionolide (EBR) on mold decay caused by Rhizopus stolonifer and its capability to activate biochemical defense reactions in postharvest peaches. The treatment of EBR at 5 μM possessed the optimum effectiveness on inhibiting the Rhizopus rot in peach fruit among all treatments. The EBR treatment significantly up-regulated the expression levels of a set of defense-related enzymes and PR genes that included PpCHI, PpGns1, PpPAL, PpNPR1, PpPR1 and PpPR4 as well as led to an enhancement for biosynthesis of phenolics and lignins in peaches during the incubation at 20 °C. Interestingly, the EBR-treated peaches exhibited more striking expressions of PR genes and accumulation of antifungal compounds upon inoculation with the pathogen, indicating a priming defense could be activated by EBR. On the other hand, 5 μM EBR exhibited direct toxicity on fungal proliferation of R. stolonifer in vitro. Thus, we concluded that 5 μM EBR inhibited the Rhizopus rot in peach fruit probably by a direct inhibitory effect on pathogen growth and an indirect induction of a priming resistance. These findings provided a potential alternative for control of fungal infection in peaches during the postharvest storage.

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Microalgae are promising alternatives to sequestration of carbon and reduction of environmental problems, e.g. the greenhouse effect and industrial water pollution. Depending on the growth conditions, microalgae can differ in their metabolism products, leading them to grow at different rates. Intracellular reactions and nutritional requirements from cell metabolism, as well as biomass composition, may vary in function of the temperature. In this study, the biotechnological potential of three microalgae strains from the species was evaluated in terms of growth, biomass composition, fatty acid profile, and chlorophyll and carotenoids contents. Each of the three species demonstrated different potential depending on their metabolisms: Scenedesmus spinosus presented fastest growth and had the highest protein content (52.99%), Pseudokirchneriella subcapitata presented the highest content of lipid extracted (26.51%), and Scenedesmus acuminatus showed increased production of chlorophyll (5.25 mg l–1) and carotenoid (1.02 mg l–1) pigments.

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Consumer concern over artificial food additives has stimulated production of pigments from natural sources. The aim of this study was to examine the effects of process variables on the content of colour compounds (betaxanthin and betacyanin) in beetroot peel juice extracted by conventional method. In this research, the extraction processes were carried out according to the central composite design with different process variables. Quantitative measurements of the basic colour compounds in beetroot extract were performed using spectrophotometer. From our experiment, it was found that the most adequate extraction conditions, which gave the highest yield of colour compounds (952.5 mg l–1 of betaxanthin and 1361 mg l–1 of betacyanin), were extraction time 1 h, operating temperature 20 ºC, and solvent ratio 0.8 w/v. Being a conventional heating method, it is a simple and cost efficient process with relatively high yield.

Open access

Tomatoes (Solanum lycopersicon L.) are one of the most important and most widely consumed vegetables in the world. The fruit contains considerable amount of different phytonutrients such as carotenoids, tocopherols, and vitamin C. In the present work, effects of some abiotic factors on the concentration of phytonutrients were investigated in tomato cultivated in two different types of soil. It was found that the type of soil had slight effect on the most important vital nutrients, while the ecological factors, particularly precipitation and average temperature 3 weeks before harvest, were of significant influence on such nutrients. It was found that low temperature and high precipitation before harvest caused the levels of carotenoids, tocopherol, and vitamin C to significantly increase by 65%, 46%, and 28%, respectively.

Open access

Barberry is a native Iranian plant including species Berberis integerrima and B. vulgaris. Barberry fruit is used for preparing sauces, jellies, carbonated drinks, candies, food colour powders, jams, marmalades, chocolates, juices, and nectars. They are used as a natural food colorant rich in anthocyanins instead of harmful artificial ones. They contain polyphenols and antioxidants that reduce damage from free radicals and prevent chronic diseases and cancers. Barberry fruit extracts were encapsulated in maltodextrin by spray drying and Liposome Entrapment. The sizes of spray dried particles were reported 1–20 μm by SEM. Dimensions of empty and extract loaded liposomes (B. vulgaris and B. integerrima) were 18–28, 37–51, and 51–77 nm, respectively, by FE-SEM. The moist diameter of liposomes measured by dynamic light scattering (DLS) method at day 0 and after 6 months at –18 °C were as follows; empty liposomes: 163.9±2.23 and 378.90±4.98, liposomes loaded with extracts: 135.2±2.04 and 160.90±2.19 (B. vulgaris) and 113.4±1.83 and 144.20±2.01 nm (B. integerrima). Evaluation of thermal-oxidative decomposition from Differential scanning calorimetry (DSC) results at 0–45–90 days showed that the antioxidant activity and the onset temperature of the encapsulated extract was higher than the control. The extracts encapsulated in liposomes, especially B. integerrima extract, had better antioxidant properties.

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There is a great demand for developing efficient anthocyanins extraction related to each plant material. Conventional methods have been replaced by novel techniques, but they might remain attractive when combined with the latter. Anthocyanins extraction from fresh and dried red cabbage was investigated by maceration, ultrasonication, and with enzymes. Pre-treatments through drying determined an improved extraction with respect to fresh samples, freeze-drying emerging as the best method. Combined enzyme-assisted extraction with maceration resulted in higher yield by conducting several extractions (1078.8±12.5 mg/100 g DW). The kinetic studies revealed good stability of anthocyanins at 50 °C, while constant degradation at 80 °C. The rate constant k at 80 °C and pH 3.5 was 1.7 10–3 min–1 and the half-life time t 1/2 was 6.7 h. Thermal analysis evidenced heat-induced changes in particular for extracts undergoing pre-heating. These results are valuable for optimal processing conditions of anthocyanins-containing products.

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