Tag Archives: sensor

700–706 J. Hart, and V. Hartová
The next generation of multiple temperature sensor
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The next generation of multiple temperature sensor

J. Hart¹,* and V. Hartová²

¹ Czech University of Life Sciences Prague (CULS), Faculty of Engineering, Department of Technological Equipment of Buildings, Kamýcká 129, CZ165 21 Prague, Czech Republic
² Czech University of Life Sciences Prague (CULS), Faculty of Engineering, Department of Vehicles and Ground Transport, Kamýcká 129, CZ165 21 Prague, Czech Republic
*Correspondence: janhart77@gmail.com

Abstract:

Long-term and short-term measurements of temperature at different depths in soil have always been very complicated. The solution that was used until now was measuring using soil thermometers. Measurements were done at shallow depths and generally only allowed for measuring of one temperature, and always at the one depth which was determined for the measurement (normally 5, 10, 20, 50, 100, 150 and 300 cm). These problems were relatively limiting and impractical. It was therefore necessary to devise an alternative for a simple and effective solution that would eliminate these disadvantages – it was necessary for a probe to allow temperature to be measured at different depths at one measuring point without having to change its position. A requirement simultaneously arose for the need to be able to measure temperatures at greater depths, and a multiple probe was therefore conceived consisting of a rod for dynamic penetration tests.

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1119–1126 P. Neuberger and P. Kic
The use of unsteady method for determination of thermal conductivity of porous construction materials in real conditions
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The use of unsteady method for determination of thermal conductivity of porous construction materials in real conditions

P. Neuberger¹* and P. Kic²

¹ Czech University of Life Sciences Prague, Faculty of Engineering, Department of Mechanical Engineering, Kamýcká 129, CZ165 21 Prague, Czech Republic
² Czech University of Life Sciences Prague, Faculty of Engineering, Department of Technological Equipment of Buildings, Kamýcká 129, CZ165 21 Prague, Czech Republic
*Correspondence: neuberger@tf.czu.cz

Abstract:

The possibility to determine the thermal conductivity of construction materials outside the laboratory conditions is useful for professional practice mainly for control and inspection activities on real existing buildings. The requirement to determine the thermal conductivity can be useful above all for different thermal insulation materials but for other materials as well, even for compact soils or rocks. This paper describes methods and instrument which can be used for these measurements, as well as the results of measurement of porous building materials. Measurements presented in this paper were carried out by the needle and surface sensor. Four different materials were selected for verification of technical parameters of Isomet 2104. Besides the thermal conductivity there were determined also thermal diffusivity and volume-specific heat capacity of materials. The carried out measurements confirmed the applicability of this device for practical measurements of thermal conductivity in real conditions. For porous materials, there were determined significant differences between the data presented by the manufacturer or in the literature and measured values, in some cases. Differences between the measured values of thermal diffusivity and volume-specific heat capacity of porous materials were always statistically significant. Authors tested different materials including thermal insulation based on agricultural products.

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1088–1098 V. Osadcuks and A. PeckaV. Osadcuks and A. Pecka
Electrical field based detection of fruits and vegetables for robotized horticulture
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Electrical field based detection of fruits and vegetables for robotized horticulture

V. Osadcuks* and A. PeckaV. Osadcuks* and A. Pecka

Latvia University of Agriculture, Faculty of Engineering, Department of Energetics, Cakstes blvd. 5, LV-3001 Jelgava, Latvia; *Correspondence: vtl@tvnet.lv

Abstract:

In this research authors study possibilities of using transmitting-type electric field based sensors for recognition of fruits and vegetables. The main idea is to detect distortions of electrical field between electrodes of sensors by measuring capacitance changes for these electrodes. Electrical field is strongly affected by relative permittivity of medium, which is several times larger for fruits and vegetables consisting mainly of water than for surrounding air, leaves and other low-mass non-conductive objects. This could help to develop electrical field sensing device with number of electrodes for detection of fruits or vegetables and determining their position thus serving as additional sensor in multi sensor system with optical camera or as stand alone device. The research covers both theoretical aspect of proposed approach and experimental evaluation of prototype device based on mixed signal controller MGC3130 originally intended for electrical field based gesture sensing periphery for consumer electronics. Main results show that in worst condition when an electrode is fully covered with a physical model of leaf 43% of signal value in comparison to sensor output without obstacle is still usable. Thus this type of sensors potentially can be an integral part of complex fruit or vegetable recognition system in robotized horticulture applications. 

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768–778 M. Hromasová and M. Linda
Analysis of rapid temperature changes
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Analysis of rapid temperature changes

M. Hromasová* and M. Linda

Czech University of Life Sciences in Prague, Faculty of Engineering, Department of Electrical Engineering and Automation, Kamycka 129, CZ165 21 Praha – Suchdol, Czech Republic
*Correspondence: hromasova@tf.czu.cz

Abstract:

 The analysis of rapid temperature changes in the dynamic system is described in the paper. Temperature changes are in range of tens of milliseconds. The sensor we used has a significant influence on the dynamic system. In these cases we need to use thermocouples that have appropriate transfer characteristics and can be manufactured with a low time constant. The time constant directly corresponds with weight and size of the sensor. The quality factor is usually in a range between 0.98 and 0.995. Information about the temperature course is particularly important in the field of dynamic systems, e.g. agricultural machines where the switching components are overloaded by pulse switching of technology systems. For the object analysis we use the thermocouples with diameter 0.012 mm with non-encapsulated finish and 0.12 mm with suppression of interference impact and comparative temperature fluctuation. For the analysis of dynamic temperature changes we conduct a measurement with a load factor change, which is the mean value of power change, expressed as ratio of the pulse duration to the delay between pulses, this way we will affect the measurement conditions. As a solution we use measurement methods for a steady state, an impulse test and a method of local measurement of temperature. Compared to a real principle of a component we do not increase temperature of the environment during experiments. The results of measurement can be applied for design and implementation of switching systems for electronic circuits with signal modulation and power load.

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73-80 D. Hoffmann, A. Rybka, M. Linda and M. Kříž
Detection of anchoring columns in low trellis
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Detection of anchoring columns in low trellis

D. Hoffmann*, A. Rybka, M. Linda and M. Kříž

Czech University of Life Sciences Prague, Faculty of Engineering, Kamýcká 129, 16521 Prague 6 – Suchdol, Czech Republic; *Correspondence: dhoffmann@tf.czu.cz

Abstract:

Low trellis of hop field was emerged in the Czech Republic in the mid-nineties of the 20th century. Growing hops in a low trellis has already been tested in 1991 by Hop Research Institute Ltd. in Žatec. However, at that time, the lack of adequate (the dwarf) varieties and special techniques prevent to their expansion. For full use low trellis is necessary mechanization, that is already currently being developed. The main advantage of growing hops at low trellis is costs reduce. Some experts say cost reduction to 50%. Cost reduction is the result of simplifying the spring and harvest work (using a mobile harvester). Currently, a prototype of a mechanical cutter is tested in field conditions. Activity of mechanical cutter is now controlled directly by the tractor driver. This control of mechanical cutter (or rather inter-axle carrier on which it is cutter mounted) puts on the tractor driver too high demands on precision. Failure to comply with the conditions set comes in contact the trimming disc with anchor pillar and the mutual damage. The movement of inter-axle carrier would therefore be appropriate automatically. But at first, it is necessary to solve recognition (detection) anchoring columns of the low trellis. During the cutting of hops needed to ensure the most accurate copy of the columns by the trimming disc, to be trimmed hop vines and hops growing in close proximity (distance hops from the anchoring column is about 150 mm). The paper presents several types of sensors and describes their advantages and disadvantages. For laboratory test was developed model low trellis comprising also hop vine, at which were referred sensors tested. This article analyzes the measured results of individual sensors and it is shown, that not all sensors are suitable for this field application. In conclusion are recommendations for follow-up research.

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