scholarly journals MATHEMATICAL SIMULATION OF A DEVICE WITH FREQUENCY OUTPUT FOR MEASUREMENT OF HUMIDITY

2021 ◽  
Vol 297 (3) ◽  
pp. 124-130
Author(s):  
A. OSADCHUK ◽  
L. KRYLIK ◽  
I. OSADCHUK ◽  
O. ZVIAHIN ◽  
Keyword(s):  
Relative Humidity ◽  
Field Effect ◽  
Experimental Studies ◽  
Bipolar Transistor ◽  
Oscillatory Circuit ◽  
Average Value ◽  
Resistive Element ◽  
Humidity Transducer ◽  
Capacitive Component ◽  
Moisture Sensitive

The device for measuring humidity with a moisture-sensitive resistive element HR202 has been developed. The self-generating transducer is designed as a hybrid integrated circuit based on a bipolar transistor VT1 and a field-effect two-gate transistor VT2. The negative differential resistance, which is formed by the parallel connection of the impedance with a capacitive component at the collector electrodes of the bipolar transistor VT1, the drain of the field-effect transistor VT2 and inductance L1, leads to the occurrence of electrical oscillations in the circuit. When exposed to moisture on the sensitive resistive element RW, the capacitive component of the impedance at the electrodes of the transistor structure changes, which causes an effective change in the frequency of the oscillatory circuit. On the basis of mathematical modeling of electrical characteristics, analytical expressions for the transformation function and the sensitivity equation are obtained. It has been experimentally established that an increase in the ambient temperature in the range of relative humidity W = 30 ÷ 85% leads to an expansion of the generation range of the autogenerating humidity transducer, as well as to an increase in the sensitivity of the device to the measured value. The generation range of the autogenerating humidity transducer at a temperature of T = 20 °C acquires a value of 823 kHz (the average value of the sensitivity is 16.18 kHz /%), and at a temperature of T = 50 °C – 1323 kHz (the average value of the sensitivity is 29.10 kHz / %). To confirm the theoretical results of circuit solutions developed device in the computer modeling of LTSpice modeling environment. The studies were carried out at different temperatures (20°C, 30°C, 40°C, 50°C) in the range of change in the resistance of the moisture-sensitive resistive element from 1750 kOhm to 2.1 kOhm, which corresponds to an increase in the value of the relative air humidity from 30 % to 90 %. The results of theoretical and experimental studies have shown that at the output there are periodic oscillations device for measuring the humidity rate which increases with increasing values ​​of relative humidity. The obtained theoretical and experimental studies are in good agreement, the relative error does not exceed 2.5%.

scholarly journals MATHEMATICAL SIMULATION OF A DEVICE WITH FREQUENCY OUTPUT FOR MEASUREMENT OF HUMIDITY

2021 ◽  
Vol 295 (2) ◽  
pp. 282-288
Author(s):  
A. OSADCHUK ◽  
◽  
L. KRYLIK ◽  
I. OSADCHUK ◽  
O. ZVIAHIN ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Field Effect ◽  
Experimental Studies ◽  
Bipolar Transistor ◽  
Oscillatory Circuit ◽  
Average Value ◽  
Resistive Element ◽  
Humidity Transducer ◽  
Capacitive Component ◽  
Moisture Sensitive

The device for measuring humidity with a moisture-sensitive resistive element HR202 has been developed. The self-generating transducer is designed as a hybrid integrated circuit based on a bipolar transistor VT1 and a field-effect two-gate transistor VT2. The negative differential resistance, which is formed by the parallel connection of the impedance with a capacitive component at the collector electrodes of the bipolar transistor VT1, the drain of the field-effect transistor VT2 and inductance L1, leads to the occurrence of electrical oscillations in the circuit. When exposed to moisture on the sensitive resistive element RW, the capacitive component of the impedance at the electrodes of the transistor structure changes, which causes an effective change in the frequency of the oscillatory circuit. On the basis of mathematical modeling of electrical characteristics, analytical expressions for the transformation function and the sensitivity equation are obtained. It has been experimentally established that an increase in the ambient temperature in the range of relative humidity W = 30 ÷ 85% leads to an expansion of the generation range of the autogenerating humidity transducer, as well as to an increase in the sensitivity of the device to the measured value. The generation range of the autogenerating humidity transducer at a temperature of T = 20 °C acquires a value of 823 kHz (the average value of the sensitivity is 16.18 kHz /%), and at a temperature of T = 50 °C – 1323 kHz (the average value of the sensitivity is 29.10 kHz / %). To confirm the theoretical results of circuit solutions developed device in the computer modeling of LTSpice modeling environment. The studies were carried out at different temperatures (20°C, 30°C, 40°C, 50°C) in the range of change in the resistance of the moisture-sensitive resistive element from 1750 kOhm to 2.1 kOhm, which corresponds to an increase in the value of the relative air humidity from 30 % to 90 %. The results of theoretical and experimental studies have shown that at the output there are periodic oscillations device for measuring the humidity rate which increases with increasing values ​​of relative humidity. The obtained theoretical and experimental studies are in good agreement, the relative error does not exceed 2.5%.

scholarly journals DRYING STUDY OF EUCALYTPTUS STAIGERIANA LEAVES BY MONITORING THE HUMIDITY OF THE DRYER DISCHARGE

2005 ◽  
Vol 4 (1) ◽  
Author(s):  
N. P. Braga ◽  
A. Starquit ◽  
M. A. Cremasco ◽  
J. O. Brito
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Light Phase ◽  
Drying Time ◽  
Humidity Transducer ◽  
Drying Kinetic ◽  
Heavy Phase ◽  
Simultaneous Heat ◽  
Analytical Scale ◽  
Air Humidification

The drying phenomenon can be treated as simultaneous heat and mass transfer in both the light and heavy phases. In the present case, the phenomenon’s evolution is normally observed through the heating of and moisture removal from the heavy phase. On the other hand, while the material is heating, the light phase is cooling and humidifying. The goal of the present work is to present discharge air humidification curves as a function of the drying time for Eucalyptus staigeriana leaves drying experiments. For the air humidification measurements, a dry bulb thermocouple and relative humidity transducer were installed at both the dryer inlet and outlet. The dryer was linked to a data acquisition system, which recorded the dry bulb temperature and the relative humidity with time. These data were later used to calculate the air moisture content at the dryer inlet and outlet. The data obtained by this methodology are compared with the ones from drying kinetic (moisture content removing of the heavy phase along time), acquired by the evolution of wet material weight through the use of an analytical scale.

scholarly journals INFLUENCE OF MICROBIAL CARBONATE MINERALIZATION ON HYDROPHOBICITY OF A CEMENT STONE SURFACE

2020 ◽  
pp. 19-25
Author(s):  
U. Duhanina ◽  
V. Strokova ◽  
D. Balickiy
Keyword(s):  
Calcium Carbonate ◽  
Experimental Studies ◽  
Wetting Angle ◽  
Cement Stone ◽  
Stone Surface ◽  
Lysinibacillus Sphaericus ◽  
Average Value ◽  
Microbial Carbonate ◽  
Contact Wetting Angle ◽  
The Relationship

The effect of microbial carbonate mineralization on increasing the hydrophobicity of the cement stone surface is theoretically justified and experimentally confirmed. Based on experimental studies and analysis of literature data, the main stages of microbial-induced sedimentation of calcium carbonate on the surface of a cement stone are formulated. Changes in the morphology of the cement stone surface due to crystalline new formations formed during biomineralization in the postgenetic period are described. It is shown that biocolmatation of the interstitial space of a cement stone by crystalline new formations leads to an increase in hydrophobicity, as evidenced by an increase in the contact wetting angle. The relationship between the change in the concentration of calcium in neoplasms and the average value of the contact wetting angle on the surface of the cement stone from the type of bacterial culture is established. According to chemical and morphological analysis of bioinduction tumors on the surface of samples and also evaluation of changes of the contact angle compared to the original index for cement, bacterial cultures are ranked in order to increase the efficiency of use for sedimentation of calcium carbonate with their participation, as well as increase of cement materials hydrophobicity in the following sequence: Sporosarcina pasteurii  Bacillus megaterium  Lysinibacillus sphaericus  Bacillus pumilus.

Influence of Temperature and Relative Humidity on Perm-Selectivity of PET Packaging Film

2011 ◽  
Vol 295-297 ◽  
pp. 1206-1210
Author(s):  
Yan Feng Guo ◽  
Xian Ping Ma ◽  
Yu Yan ◽  
Yun Gang Fu
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Experimental Studies ◽  
Thermodynamic Temperature ◽  
Packaging Film ◽  
Influence Of Temperature ◽  
Carbon Dioxide Gas ◽  
Pet Film ◽  
Pet Films ◽  
Temperature Water

The main feature of this article is the investigation on the influence of temperature, relative humidity, film thickness on permeability of PET packaging film, the analysis of perm-selectivity of the packaging films for oxygen gas and carbon dioxide gas, and the evaluation on experimental formulas of water vapor, O2 and CO2 gas permeating rates on the basis of gas molecular osmotic reaction kinetics and regression analysis. The comparison between experimental studies and calculation indicates that: (1) with increment of ambient temperature water vapor, O2 and CO2 permeating rate of PET films and PET/Al film also rise, and the logarithm of water vapor, O2 and CO2 gas permeating rates has linear relation with the reciprocal of thermodynamic temperature, and (2) the influence of relative humidity on water vapor permeating rate of PET film with thickness 12µm is the least, and that of PET film with thickness 20µm and PET/Al film with thickness 18µm is a little obvious. (3) The PET films hold remarkable perm-selectivity for O2 and CO2 gas, and CO2 gas permeating rate is about two times of O2 gas, yet O2 and CO2 gas permeating rates of PET/Al film are both very low and have small difference, so the PET/Al film has better barrier performance than the PET film.

Studies of Magnetically Active Silicone Elastomers on a Vibrostend

2021 ◽  
Vol 1037 ◽  
pp. 141-147
Author(s):  
Andrey Minaev ◽  
Juri Korovkin ◽  
Hammat Valiev ◽  
G.V. Stepanov ◽  
Dmitry Yu. Borin
Keyword(s):  
Magnetic Field ◽  
Field Effect ◽  
Dynamic Properties ◽  
Experimental Studies ◽  
Magnetic Field Effect ◽  
Magnetorheological Elastomer ◽  
Silicone Elastomers ◽  
Damping Coefficients ◽  
Deformation Properties ◽  
The Magnetic Field

Experimental studies magnetorheological elastomer specimens dynamic properties under the magnetic fields action on the vibrostend are carried out. Amplitude-frequency characteristics have been obtained. The magnetic field effect on the silicone magnetoreactive elastomers deformation properties and damping coefficients experimentally is established.

scholarly journals Hygrothermal Behaviour of Ventilation Cavities in Highly Insulated Envelopes

2020 ◽  
Vol 172 ◽  
pp. 07003
Author(s):  
Klaus Viljanen ◽  
Xiaoshu Lü ◽  
Jari Puttonen
Keyword(s):  
Heat Flux ◽  
Relative Humidity ◽  
Experimental Studies ◽  
Thermal Transmittance ◽  
The Future ◽  
U Value ◽  
Hygrothermal Behaviour

This article presents long-term experimental studies on the moisture safety in the ventilation cavities of highly insulated (HI) structures. The tested HI-walls had thermal transmittances of 0.11-0.13 W/m2K. A wall with a thermal transmittance of 0.23 W/m2K represented the baseline wall in the test. In addition to walls, an HI-roof of a newly built house with a U-value of 0.08 W/m2K was measured. The results indicate that, in the ventilation cavity, the relative humidity of an HI-wall exceeds 1-7% of the humidity measured from the baseline wall during winter, which coincides with the 0.4-1.5ºC lower temperatures observed in the HI-walls. The mold risk in the ventilation cavities of the walls is low, as the value of the mold index (MI) remains below one, which indicates small amounts of microscopic mold only on surfaces. However, at the bottom of the cavity, the MI value reaches 1.4 due to lower temperatures. In the HI-roof, the MI values are between 1.0 and 2.0 in the middle of the cavity in winter. The reasons for the higher mold risk of the roof are the humid weather, the built-in moisture of the roof and the low heat flux from inside. The study confirms that, in the future, warmer weather and increased humidity can increase moisture risks in the ventilation cavities. The results support the use of materials that are more resistant to mold in the outer parts of structures.

Empirical Formulation for number of ice crystal fragments by sublimational breakup

2020 ◽  
Author(s):  
Akash Deshmukh ◽  
Vaughan Phillips
Keyword(s):  
Relative Humidity ◽  
Cloud Model ◽  
Experimental Studies ◽  
Ice Crystal ◽  
Initial Size ◽  
Sublimation Process ◽  
Numerical Formulation ◽  
High Concentrations ◽  
Ice Multiplication ◽  
Ice Production

<p>There is much uncertainty about high concentrations of ice observed in clouds and their origins. In the literature, there have been previous experimental studies reported about the sublimation process of an ice crystal causes emission of fragments by breakup.   Such sublimational breakup is a type of secondary ice production, which in natural clouds can cause ice multiplication. </p><p>To represent this process of sublimation breakup in any cloud model, the present study proposes a numerical formulation of the number of ice fragments generated by sublimation of pristine ice crystal. This is done by amalgamating laboratory observations from previous published studies. The number of ice fragments determined by relative humidity (RH) and initial size of the ice particle were measured in the published experiments, and by simulating them we are able to infer parameters of a sublimation breakup scheme.   At small initial sizes, the dependency on size prevails, whereas at larger sizes both dependencies are comparable. This formulation is compared with observations to see the behaviour of it.</p>

Silicon Carbide Field Effect Transistors for Detection of Ultra-Low Concentrations of Hazardous Volatile Organic Compounds

2014 ◽  
Vol 778-780 ◽  
pp. 1067-1070 ◽  
Author(s):  
Donatella Puglisi ◽  
Jens Eriksson ◽  
Christian Bur ◽  
Andreas Schütze ◽  
Anita Lloyd Spetz ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Volatile Organic Compounds ◽  
Relative Humidity ◽  
Organic Compounds ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Long Term Stability ◽  
Volatile Organic ◽  
Recovery Times ◽  
Response And Recovery

Gas sensitive silicon carbide field effect transistors with nanostructured Ir gate layers have been used for the first time for sensitive detection of volatile organic compounds (VOCs) at part per billion level for indoor air quality applications. Formaldehyde, naphthalene, and benzene have been used as typical VOCs in dry air and under 10% and 20% relative humidity. A single VOC was used at a time to study long-term stability, repeatability, temperature dependence, effect of relative humidity, sensitivity, response and recovery times of the sensors.

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