Silicon MEMS Thermocatalytic Gas Sensor in Miniature Surface Mounted Device Form

A reduced size thermocatalytic gas sensor was developed for the detection of methane over the 20% of the explosive concentration. The sensor chip is formed from two membranes with a 150 µm diameter heated area in their centers and covered with highly dispersed nano-sized catalyst and inert reference, respectively. The power dissipation of the chip is well below 70 mW at the 530 °C maximum operation temperature. The chip is mounted in a novel surface mounted metal-ceramic sensor package in the form-factor of SOT-89. The sensitivity of the device is 10 mV/v%, whereas the response and recovery times without the additional carbon filter over the chip are <500 ms and <2 s, respectively. The tests have shown the reliability of the new design concerning the hotplate stability and massive encapsulation, but the high degradation rate of the catalyst coupled with its modest chemical power limits the use of the sensor only in pulsed mode of operation. The optimized pulsed mode reduces the average power consumption below 2 mW.

TECHNOLOGICAL REQUIREMENTS FOR MECHANIZATION PORK PRODUCTION

The purpose of the research is – develop technological requirements for technical means for pork production on pig farms, adapted to EU standards. Research methods. During the development of technological requirements for mechanization of pork production on pig farms, adapted to EU standards, the basic regulatory documents were used: EU Directive 91/630 of 19.11.1991; EU Directive 2008/120 of 18.12.2008. Technological requirements for mechanization of pork production are formed by the following components: keeping pigs, feeding pigs, watering pigs, removing manure, creating a microclimate, veterinary services. Research results.Technological requirements for mechanization of pork production were developed for the first time in Ukraine. The design of equipment for keeping pigs must provide conditions for keeping animals close to natural. In accordance with EU regulatory requirements, free conditions for keeping animals must be ensured. The technological area of the machine per animal must be at least: 0.15 m2 for pigs with an average live weight of up to 10 kg; 0,2 m2 for pigs with an average live weight of 10 kg to 20 kg; 0,3 m2 for pigs with an average live weight of 20 kg to 30 kg; 0,4 m2 for pigs with an average live weight of 30 kg to 50 kg; 0,55 m2 for pigs with an average live weight of 50 kg to 85 kg; 0,65 m2 for pigs with an average live weight of 85 to 110 kg; 1,0 m2 for pigs with an average live weight of more than 110 kg. Dimensions of individual machines for keeping pigs: width - 60 cm, length - 170 cm, area 1,0 m2; sows - width - 65 cm, length - 190 cm, area 1,2 m2. The number of pigs in the technological group must be at least 6 heads. The minimum technological area for individual keeping of an adult boar should be 6,0-7,5 m2. The technological area of the machine for keeping the breeding boar and sow during mating must be at least 10 m2. Piglets kept near sows should be provided with a comfortable heated area. During group keeping of pigs, their simultaneous access to feed must be ensured. When creating drinking bowls for pigs, it is necessary to take into account the technological requirements regarding the need of pigs for water and its flow rate. Pigs should not be kept in conditions with high excess air temperature and high relative humidity. When creating equipment for pig breeding, it is necessary to take into account the negative impact of air currents in piggeries on animals. It is not allowed to keep pigs constantly in the dark. Conclusions. For the first time in Ukraine, technological requirements for technical means for pork production on pig farms, adapted to EU standards, have been developed, taking into account the following components: keeping, feeding, watering pigs, manure removal, creating a microclimate, veterinary services. Technological requirements will be useful in the creation and implementation of modern machinery and equipment for pig farms.

Calculation of aerial contact wire volume heated by a moving electric ARC

The article is devoted to the study of the problem of electrified railways electric locomotive current collectors’ interaction violation with an aerial contact wire, accompanied by the occurrence of an electric arc. Current collection disorders, accompanied by arcing, have a destructive effect on the contacting elements, causing their thermal erosion. Places where current collection violations occur should be registered and diagnosed in a timely manner in order to prevent an emergency situation associated with burnout or breakage of the aerial contact wire. In order to further develop the system of technical diagnostics for current collection disorders accompanied by arcing, it is necessary to study the nature and parameters of the processes occurring during these violations. The main part of the article is devoted to the study of the area of heating the aerial contact wire by a moving electric arc. The characteristics describing the heated area are geometric parameters, including the area in the cross section of the wire and the volume of the area. To obtain the necessary data, the method of heat sources was applied, which is a mathematical model that describes the process of heat propagation in an aerial contact wire. The electric arc arising when the current collector breaks off is considered as a mobile heat source distributed over the aerial contact wire surface in the heating zone and having a limited radius of the heating spot. Based on the heat propagation process peculiarities inside the aerial contact wire, a method for calculating the volume of the heated area bounded by an isothermal surface of a certain temperature is presented. The heated area was visualized using the PTC MathCAD.

Buckling and Vibration Performance of a Composite Laminated Plate with Elastic Boundaries Subjected to Local Thermal Loading

In this paper, a model is established for the calculation of the vibrations of a composite laminated plate with elastic boundary conditions subjected to local thermal loading. The model is based on first-order shear deformation theory using the finite element method. The influence of boundary conditions, heating area, and heating location on buckling and vibrations of a composite laminated plate was investigated, and there were two stages in which the critical temperature increased sharply during the transition from free boundary to simply supported and rigid fixed boundaries. The thermal buckling of locally heated laminated plates is generally not checked in practical applications unless the heated area exceeds approximately 10% of the total area of the plates. The stronger the boundary constraint is, the greater the influence of the heated area is on the vibrational frequencies of the composite laminated plate.

A comparative benchmarking study of multi-storey residential buildings in two periods of energy saving efforts: the 1980s and the 2010s

In 1990, Technological Institute (TI) in Denmark made a benchmarking study of 92 typical multi-storey buildings covering 23 000 dwellings. The study included measurement data from the 1970s and the years after the energy crises. This study showed that over a period of less than 20 years a significant reduction in energy consumption took place. In a new similar study, TI and Aalborg University have analysed 62 buildings covering 18 000 dwellings including measurement data from the last 20 years. This time, the data covers a period with an increasing focus on the carbon-emission impacts of energy consumption. As opposed to the first benchmarking study, the new 20-years study shows that the heat consumption has been almost constant over the last 20 years. This paper presents a comparative study of the two sets of measurements and evaluates energy saving efforts and individual building energy performance. Furthermore, the paper compares two different ways of deriving benchmarks from the data and demonstrates how utilizing change-point models/energy signature as opposed to the more traditional mean annual values per heated area, significantly increases the usability.

Preliminary assessment of the building design of a new test house in Nuuk, Greenland

DTU has established a single-family three-level test house in Nuuk, Greenland. The main idea of the house was to have a relatively small heated area but a split building envelope, where a ventilated space behind the rain screen in some areas could be used as a sunroom. This paper describes the process of transforming the architectural ideas to a test building. Main issues have been how to design the rain screen and how to ventilate the space behind the rain screen.

PSXVI-21 The effect of enhancing the thermal environment of piglets on physiology, behavior and productivity

To determine if increasing the heated area provided to piglets may improve their welfare; Sows (n = 27) were assigned to stalls using a traditional heat lamp (Control), or stalls using 2, 0.4 x 2.4 m heated mats (Heat). The mat temperature was maintained at approximately 39 °C until the 3rd d post-farrowing when they were replaced with a traditional heat lamp. At 1 d of age, piglets’ temperature was recorded, and blood samples were taken from 4 piglets per litter to measure cortisol, lactate, and glucose. Of these piglets, 2 were females and 2 males, 1 each weighing above average (thrifty) and 1 each below average (unthrifty). ADG of all piglets and mortality were recorded on d 3, when the heated mats were replaced with heat lamps, as well as at weaning. There were no treatment differences (P &gt; 0.10) for cortisol (4.52 ± 0.22 ug/dL), glucose (102.84 ± 2.11 mg/dL), or lactate (2.42 ± 94.77 mmol/L). Unthrifty piglets had greater cortisol concentrations (5.45 ± 0.34 vs. 3.64 ± 0.24 ug/dL, P &lt; 0.0001) and lower glucose (97.3 ± 3.06 vs. 108.37 ± 2.76 mg/dL; P &lt; 0.0014) than thrifty. ADG was not different (P &gt; 0.10) on d 3 (0.12 ± 0.01 kg) or at weaning (0.24 ± 0.003 kg). There was no difference in body temperature between treatments (39.23 ± 0.03 °F, P &gt; 0.10). Day 3 mortality was lower in Heat crates than Control (0.04 ± 0.02 vs. 0.12 ± 0.03, P &lt; 0.02); however, mortality at weaning did not differ (11 ± 0.02%, P &gt; 0.10). In conclusion, increasing the warm area in farrowing crates with heated mats over the length of the piglet area may increase survivability while provided.

A Numerical Study Of Micro-Jet Impingement Cooling Inside A High Pressure Turbine Vane

A thorough numerical analysis of micro-impingement cooling for application in high pressure turbine vanes is presented. The fundamental flow of an axisymmetric jet is first modeled and studied to ascertain the validity of the results. Subsequent, a fully three dimensional curved vane is modeled with an in-line impinging array of jet diamters 0.5mm. The analysis reveals that spent air collects with increasing streamwise distance from the leading edge, thereby increasing jet exit velocities across the array. For all cases studied, an increase in jet to target spacing increased the overall Reynolds number of the array, but decreased the average heat transfer rate. Micro diameters of 0.25mm were subsequently studied for full vane geometry. For a given mass flow per unit of heated area, the micro-jets considerably increased the average heat transfer by 63%. Similar enhancements were obtained at a fixed pressure drop percentage, and for a desired average heat transfer.

A Numerical Study Of Micro-Jet Impingement Cooling Inside A High Pressure Turbine Vane

A thorough numerical analysis of micro-impingement cooling for application in high pressure turbine vanes is presented. The fundamental flow of an axisymmetric jet is first modeled and studied to ascertain the validity of the results. Subsequent, a fully three dimensional curved vane is modeled with an in-line impinging array of jet diamters 0.5mm. The analysis reveals that spent air collects with increasing streamwise distance from the leading edge, thereby increasing jet exit velocities across the array. For all cases studied, an increase in jet to target spacing increased the overall Reynolds number of the array, but decreased the average heat transfer rate. Micro diameters of 0.25mm were subsequently studied for full vane geometry. For a given mass flow per unit of heated area, the micro-jets considerably increased the average heat transfer by 63%. Similar enhancements were obtained at a fixed pressure drop percentage, and for a desired average heat transfer.

Comment on Pietrapertosa et al. How to Prioritize Energy Efficiency Intervention in Municipal Public Buildings to Decrease CO2 Emissions? A Case Study from Italy. Int. J. Environ. Res. Public Health 2020, 17, 4434

This paper responds to the article by Pietrapertosa et al., doi:10.3390/ijerph17124434, published previously in the International Journal of Environmental Research and Public Health. Its aim is to discuss the appropriateness of the studied method, to analyze its weak sides and to propose its robustness improvement. Thus, data presented in the above study were examined and recalculated, yielding, among others, indicators of annual energy savings (in kWh per m2 of total heated area) and specific proposals investment costs (in € per m2 of total heated area). By analyzing the obtained data for all public buildings, a significantly simplified approach to this problematic has been suggested while several other features of the research method and some presented results lack proper reasoning and discussion. Individual approach to each public building has been proposed and discussed point-by-point to enhance the method’s applicability. As a result, more realistic outcomes are obtained, and suitable investment actions can be proposed.