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The authors developed and constructed a new type of urological catheter, named “short catheter”. Experiments were performed with the new catheter and the valves developed for the catheter. Based on the results, one can conclude that the material Sh°60 seems to be suitable for constructing valve for short catheter. It meets the basic requirements made for the valve: less than 100 water cm pressure it is able to discharge 300 ml urine within 2 minutes. However, the valves made of material Sh°40 are better for the circumferential ribs and concerning elasticity. Because of the theoretical considerations and the conducted experiments, the form and the structure of the prototype short catheter was constructed. This prototype meets the requirements for the catheter and it is eligible to be the subject of further experiments. The experiments will focus on the determination of the flow rate through the whole catheter. In vivo experiments are planned with the new catheter.

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Obituary

In memoriam Professor András Fekete

Progress in Agricultural Engineering Sciences
Authors: Péter Szendrő and József Felföldi
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The V-belt drive is a rather popular, widely used form of power transmission in agricultural and food industry engineering. At the same time, its stability, the lifetime of V-belt is influenced by several environmental factors, namely in the food industry by the contamination affecting the belt sides, the ambient temperature, humidity and the occasionally aggressive (acidic, alkaline air, air saturated with gases, etc.) medium. In the case of agricultural machinery, the vibration caused by uncertainly oriented pulleys with bearing in different plate structures (often being shaken in the fields) as well as alignment adjustment inaccuracies jeopardize the reliability of the parameters of the drive. Furthermore, the efficiency is determined by several factors together: the slippage occurring during drive transmission, the hysteresis loss resulting from the external and internal friction occurring with the belt entering and exiting the pulley. Experimental equipment and calculation methods were developed to determine the dynamics of temperature increase generated by the belt and pulley relationship. The temperature generated in the V-belt was measured as a function of pretension, pulley diameter and bending frequency. The so-called damping factor characterizing the contact with the pulley (the external friction when entering and exiting the groove) and the hysteresis loss (inner friction) are also determined. On the basis of the damping factor (ζ400 Ns/m 2) of the V-belt involved in the experiments the other losses (P oth) occurring from the pulley—V-belt contact and internal friction may be estimated. The drive parameters may be optimized with the mathematical model describing the effect of the pulley diameter and belt frequency on the increase in temperature.

A standardized calculation method as well as design factors valid for the properly adjusted drive and normal operating conditions determined through empirical and laboratory experiments are used for the sizing of V-belt drives. The lifetime of V-belt drives designed in this way, used in extreme conditions typical of agricultural machinery will not be appropriate and will not provide clear, predictable information for maintenance planning. In such cases the results of our own many lifetime tests conducted in the given circumstances can be safely relied on.

The agricultural harvesting machines are large plate-body self-propelled structures on which most of the power supply of the (threshing, cleaning, moving, etc.) machine units handling the crop is realized via belt drives. The distance and angular displacement of the axes involved in the drive can vary within wide limits. The misalignment and angular displacement of the pulleys can be the result of installation instability — due to the plate structure — and the deformation of the plate structure occurring during the operation as well. V-belt drives operate satisfactorily under such conditions as well, however these faults are unfavourable in terms of belt lifetime and result in the reduction of drive efficiency.

A further aim of our research is to examine through experiments the lifetime and efficiency of V-belts used in agricultural machines as a function of drive adjustment errors. According to the results of the measurements of the geometrical adjustment errors of V-belt drives performed in the field, the pulleys of agricultural equipment are not always positioned in the medium plane of the drive. In our experiments these data served as independent variables. Figure 1 shows the arrangement of a V-belt drive in a grain harvester with the laser pulley alignment measuring instrument installed as an accessory. In the case of many machine types in 80% of the tested drives three times the permissible error was measured, and because of off-road use, due to dynamic load these errors further increased as a result of the frame deformation.

The results of both the belt bending testing and the geometrical adjustment testing of the drive offer great help in the design of belt drives. At the same time they can be the source of lifetime and efficiency forecasts.

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Abstract

The existing effective domestic regional development framework requires analyses for increasingly wider areas (micro, meso and even macro regions) before operational – short-term – local developments to be prepared and implemented.

Such comprehensive complex studies or larger-term programmes may demonstrate the profitability of the given project and can complement it with combined utilization technologies; in the case of Himesháza several locally known renewable energy sources could facilitate geothermal heat, later electricity supply, e.g. local biomass (biogas-based) recovery technology (organic waste of the local pig farm) and, for example, the construction of a low-power “dwarf” hydroelectric power plant chain based on rich watercourses of the region (the “southern dwarves” in Hungary) and the connection of existing solar utility facilities to a modern “smart grid” system in the longer term.

Himesháza, located in southern Hungary in Baranya county, is developing; it has a detailed feasibility study of a thermal energy supply network and an energy supply development plan.

Based on the geothermal characteristics of Baranya county it would be reasonable to encourage the development of smaller-scale, decentralized heating systems for dynamic settlements. Several settlements in close proximity to Himesháza have already explored thermal wells. Power generation with a small scale, closed-loop system can be used in the project region for thermal water with an outflow temperature of 90 °C. The heating system may also be able to fulfill the needs of recreational, vacation-based or complex thermal spa facilities formerly planned in the region. Moreover, the system could also be capable of utilizing a larger spectrum of renewable energy through its combination with photovoltaic technology.

Due to the country's favorable agricultural characteristics, Hungary's biomass potential is higher than the European average. The utilization of organic waste from agricultural and farming sectors is highly recommended in Baranya county; biogas production seems to be the most suitable in the region of Himesháza too, broadening the utilization of renewable resources.

The realization of the current project could contribute to shifting the energy resource sector in a more modern, environmentally conscious direction.

The background for shorter-term plans and investment (carried out within the framework of operational programs) necessary for the optimal operation and maintenance of longer-term (25–50 years) energy development strategies is created by the analysis (at multiple scales) of complex regional characteristics and future potential, and the selection of optimal sites.

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Chopping biomaterials is an energy consuming process where considerable losses occur because of friction and the compaction of the material. The objective of the paper reported here is to show an energy saving chopping cylinder drive mechanism and to analyze the variations in the drive torque of the chopping cylinder. The chopping mechanism consists of a flexible drive mechanism. Field experiments were performed with a chopper fitted with such a mechanism and the components of the drive torque were determined from the results. The random excitation of the flexible drive mechanism (“multikator”) is caused by the variations in the transport of the material to the chopping cylinder. Consequently there are variations in the angular speed of the chopping cylinder. These variations cause the edgewise vibration of the cutting knives and therefore the energy saving effect. The analysis of random components of cutting torque as a function of time could give an advanced method for designing machine parts operated under dynamic load. Therefore, the critical load, or stress can be calculated by the method developed. Furthermore, the lifetime and the breakdown of the machine parts can be predicted.

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The effects of microwave pre-treatment of meat industrial wastewater were investigated in this study. The focus of this investigation was to determine the optimum conditions in a continuous flow microwave treating system under which the microwave pre-treatment of meat industrial wastewater would facilitate the maximum biogas yield. Response surface analysis was applied to screen the effects of volumetric flow rate (FR), number of treating (NT) and power of the magnetron (PM).

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Pneumatic artificial muscles (PAMs) are of special importance in the field of pneumatic drives and in robotics. Different designs have been developed, but the McKibben muscle is the most popular and is made commercially available by different companies, e.g. Fluidic Muscle manufactured by Festo Company. There are a lot of advantages of PAMs like the high strength, good power/weight ratio, good power/volume ratio, low price, little maintenance needed, great compliance, compactness, flexibility, inherent safety and usage under rough environments. The objective of this research note is to determine the error of positioning with a Fluidic Muscle at cold and at normal operating temperature of the system with sliding mode control. The results of the experiments showed that the positioning error of the Fluidic Muscle under the experimental conditions was 0.01 mm.

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