Relative Humidity Measurements Research Articles

Analysis of the influence of air quality on the performance of the Boeing 737-800 evaluated during takeoff at El Dorado Airport

This paper analyzes how the Bogotá’s air quality and pollutant levels affects the Boeing 737-800 take-off performance in terms of the available runway distances and maximum \newtext{take-off} weight, which are two of the most restrictive factors in airlines' operation. The airport runway's physical characteristics, geographical position, surroundings, and atmospheric conditions affect the maximum aircraft \newtext{take-off} weight. This study examines: (a) the influence of pollutants in Bogotá’s air quality and its subsequent effects in air density; (b) the maximum available polluting agents and relative humidity measures in this city; (c) the maximum take-off weight of the aircraft with and without air degradation due to atmospheric considerations. Software called “Aircraft Take-Off Software” has been developed to determine the B737-800 most limiting take-off weight of in specific geographical and atmospheric conditions. This study reflects the effect of high populated cities pollution on the aircraft operational performance which analysis has demonstrated that the presence of high carbon dioxide concentrations in the air increase the B737-800 payload capacity taking off from Bogotá but in the other hand, relative humidity variation decreases this capacity drastically, showing that considering Bogotá’s relative humidity and pollutant levels, the most restrictive weight situation for the take-off phase is the “Climb Limit Take-Off Weight”; however, as it is an aerodynamic study of the pollutants influence in engine combustion the structural integrity was not considered and for further investigation it should be considered to determine more accurately the most restrictive take-off weight.

The Effect Micro Climate on The Flowering Phenology of Forest Clove Plants (Zyzygium obtusifolium L)

Microclimate is one of the environmental factors that affect the growth, flowering and quality of clove flower production, including forest clove plants. This study aims to explain the effect of microclimate on the flowering phenology of forest clove plants and the length of the flowering phenoplast. The research lasted for 17 months, starting from January 2020 - May 2021. The field research was carried out on the island of Ambon, Maluku. The sampling location was determined using the purposive method. Measurement of temperature and relative humidity using a thermohydrometer, solar intensity was measured using a lux meter. Data analysis used principal component regression. The results showed that the length of the flowering phenology was 167.6 days. Microclimate parameters affect the flowering phenology of forest clove plants, R-square 0.93 and the correlation is very strong (R 0.95). Air temperature and intensity of sunlight, both between stands and below stands have a negative effect, meaning that with the influence of these three variables the flowering phenology takes place earlier. On the other hand, with the air humidity variable the effect is positive, meaning that the flowering phenology will be delayed. Air temperature is the variable that has the greatest influence on the flowering phenology of forest clove plants.

Statistical analysis of climate measurements for resilient design in social housing

Climate change is a progressive phenomenon that, although it can be mitigated, it cannot be stopped. As a consequence, the level of uncertainty is high to propose resilient design strategies to counteract its effects on people's comfort and health. Likewise, a limitation is the collection of information and access to climatic data of each place, so in the present work a cycle of temperature, relative humidity and wind speed measurements was proposed in a case study of social housing in the city of Tunja, Colombia. Thus, the objective of the article is to analyze and validate the reliability of the data collected on site. For this purpose, a descriptive statistical analysis of the information was carried out with tools such as Excel and PSPP version 1.4.1. As a result, it was found that, although the average level of reliability is acceptable, there are data below the minimum value of acceptability. It was concluded that descriptive statistics allows to know the margin of error to which the data are exposed and therefore reduce the uncertainty in the resilient design

Iot application for energy poverty detection based on thermal comfort monitoring

The development of a datalogger for identifying Energy Poverty (EP) using thermal comfort monitoring is described in this work. There is not a uniform definition of EP, and no global recommendations indicating the thermal comfort characteristics that should be utilized to identify EP. Most Internet of Things (IoT)-based systems designed for EP identification measure energy consumptions (electricity and gas). There is a lack of works that use IoT-based systems to identify EP through the monitoring of thermal comfort parameters. To address the deficiencies discovered in the identification of EP from the perspective of thermal efficiency, an IoT-based monitoring system was designed, developed, and tested. A first pilot was installed in a household in Getafe. A full month of temperature, relative humidity, and CO2 concentration measurements were utilized to evaluate the system, which was then compared to a commercial system. The results revealed that the new IoT-based approach was very dependable and may be used to accurately monitor EP-related parameters.

A FIELD STUDY ON ADAPTIVE THERMAL COMFORT IN A NATURALLY VENTILATED DESIGN STUDIO CLASS IN THE POST-PANDEMIC PERIOD

Design studios are where design students spend most of their time learning theory and practices. For this reason, thermal comfort conditions in studios are crucial to provide a suitable environment for education. Especially in the post-pandemic period, thermal comfort conditions have become more critical in educational buildings. The present study focuses on the adaptive thermal comfort condition in an architectural design studio in the Mediterranean climate of Izmir/Turkey. The study aims to evaluate the comfort conditions of the students and determine the effect of mask use on thermal sensation in the post-pandemic period. For this purpose, air temperature, relative humidity, and air velocity measurements were collected during the studio hours in the spring semester when the heating and cooling systems were not working. Additionally, a thermal sensation survey was conducted with 42 students. The results showed that the thermal comfort level was within the 90% acceptability limits according to the ASHRAE Standard-55. According to the survey results, the use of masks by the students did not have a significant effect on thermal perception.

Seasonal Air Quality in Bedrooms with Natural, Mechanical or Hybrid Ventilation Systems and Varied Window Opening Behavior-Field Measurement Results

The article presents the results of measurements of temperature, relative humidity and CO2 concentration in six single-family houses’ bedrooms located in Poland, in Wrocław and vicinity, during two climatic seasons: summer–autumn and winter. Two buildings with natural ventilation (NV) were tested, three with mechanical ventilation with heat recovery (MV) and one with hybrid ventilation (HV)—mixed mode natural and mechanical. The behavior of residents regarding opening windows was analyzed and the influence of the changing internal and external conditions on their active reactions was examined. The analysis confirms and adds to the global discourse on the key impact of user behavior on securing healthy indoor air quality in housing, regardless of ventilation system or building energy standard. A disconnect exists between the observed window opening practices and typical design principles, assuming adjustment to a given ventilation system or changing weather conditions. The observations showed that in both analyzed seasons it was possible to obtain a good quality internal environment, in terms of CO2 level, regardless of the ventilation system used in the building. However, unfavorable results were observed for one bedroom, in which the inhabitants do not adapt their behavior to local technical conditions. Taking into account the level of relative humidity (RH), much higher values were observed in the NV bedrooms in both analyzed periods. The obtained results were divided into IAQ classes in accordance with the EN 16798-1. The recorded values of the internal temperature confirm the significant influence of the location of the room in the building and the actions taken by the residents.

Experimental Investigation of Thermal and Humidity Dynamics in the Enclosures Made of Non-Permeable Walls

The usage of electronics in outdoor environment is growing therefore the control of moisture related failures in electronics are becoming more important. The main cause of these failures is the humidity inside electronics which may condense on the surfaces or components. To protect electronics from harsh environment, the components and electronics are encapsulated by using electronics enclosures, however it does not prevent from moisture ingress through plastic walls, gaskets, cable feedthroughs and etc. Thus, to control the humidity, it is very important to understand the humidity ingress and behaviour in the electronics enclosures. Hence, the paper concerns the study of temperature and moisture dynamics when electronics enclosure is exposed to a cyclic temperature condition according to MIL-STD-810F. Two different enclosures were selected for the experiment, namely, aluminum enclosure and glass jar. The study was carried out in a climatic chamber and the measurements of temperature and relative humidity were performed using sensors. Different effect of enclosure material was considered for humidity ingress. In aluminum enclosure, results showed that the temperature difference between different points are smaller than in case of glass jar. Different temperatures in enclosures are determined by different boundary conditions outside the enclosure caused by the climatic chamber.

Modelling the Dynamic Response of Root Diameter Changes in Orchid to Temperature and Humidity using NARX Neural Network

Understanding the dynamic behaviour of plants is vital for realization of precision agriculture systems. This paper proposes a dynamic response model of root diameter to changes in temperature and relative humidity for commercial epiphytic orchids. A Vanda hybrid orchid is used for this study. Root diameter changes, temperature, and relative humidity measurements are logged for fifty-one days. The dynamic response of the root diameter changes is analysed and modelled using non-linear autoregressive with exogenous input neural network. The best performance is obtained with Levenberg-Marquardt algorithm, yielding the best overall regression, lowest mean squared error, and fastest training speed.

The DataHawk2 uncrewed aircraft system for atmospheric research

Abstract. The DataHawk2 (DH2) is a small, fixed-wing, uncrewed aircraft system, or UAS, developed at the University of Colorado (CU) primarily for taking detailed thermodynamic measurements of the atmospheric boundary layer. The DH2 weighs 1.7 kg and has a wingspan of 1.3 m, with a flight endurance of approximately 60 min, depending on configuration. In the DH2's most modern form, the aircraft carries a Vaisala RSS-421 sensor for pressure, temperature, and relative humidity measurements, two CU-developed infrared temperature sensors, and a CU-developed fine-wire array, in addition to sensors required to support autopilot function (pitot tube with pressure sensor, GPS receiver, inertial measurement unit), from which wind speed and direction can also be estimated. This paper presents a description of the DH2, including information on its design and development work, and puts the DH2 into context with respect to other contemporary UASs. Data from recent field work (MOSAiC, the Multidisciplinary drifting Observatory for the Study of Arctic Climate) is presented and compared with radiosondes deployed during that campaign to provide an overview of sensor and system performance. These data show good agreement across pressure, temperature, and relative humidity as well as across wind speed and direction. Additional examples of measurements provided by the DH2 are given from a variety of previous campaigns in locations ranging from the continental United States to Japan and northern Alaska. Finally, a look toward future system improvements and upcoming research campaign participation is given.

PEMBUATAN PROTOTIPE EXHAUST FAN OTOMATIS MENGUNAKAN SENSOR SUHU DHT11 UNTUK APLIKASI DIKENDARAAN DAN RUANGAN BENGKEL

Design of an automatic exhaust fan prototype using a DHT11 temperature sensor is the manufacture of an electronic device to lower the temperature in a room and suck air in the room to be discharged outside the room, at the same time the exhaust fan draws fresh air outside into the room. In addition, the exhaust fan can also circulate air in a room, in order to stay healthy the room needs air circulation so that there is always a change of indoor air with fresh air from outside. This tool works automatically because this tool uses a temperature and humidity sensor type DHT11. This tool is still being made in the form of a prototype or initial model which is an example before making the actual tool. In this prototype, room temperature and humidity data are detected by the DHT11 sensor. The DHT11 temperature sensor detects the room temperature, then it is processed by the microcontroller then the exhaust fan will rotate to suck air out of the room by providing a calibrated digital signal. 30-50°C and a relative humidity measurement range of 20-90%. The input voltage is 12 volts and 5 volts is changed by the power supply. Arduino microcontroller works at a voltage of 5 volts and a voltage of 12 volts for the relay circuit and the exhaust fan will turn on at a temperature of more than 30 ° if the temperature is less than 30 ° C then the exhaust fan must stop rotating.

Application of K-Means Clustering and Calendar View Visualisation for Air Pollution Index Analysis

Two years of diurnal concentration of particulate matter (PM10 ) and nitrogen dioxide with the addition of relative humidity measurement, collected from Putrajaya, Malaysia’s ground-based measurement station from January 2014 to December 2015, were analysed. K-means clustering was employed and optimal clusters of four were identified for each year based on the most suggested number of clusters from internal cluster validation measures of the total within sum of square, silhouette index and gap statistics. Each cluster was then profiled where each mean pollutant sub-indices were calculated and the contributing pollutant to the air pollution index (API) was determined by looking at the maximum value from all sub-indices. This mechanism closely follows the Recommended Malaysian Air Quality Guidelines (RMG) for determining API. Particulate matter was found to be the dominant sub-index in all clusters and then paired with the mean relative humidity for visualisation. A calendar view was selected to show the temporal patterns and we observed a consistent cluster profile with the actual mean values of the selected parameters for most months. The calendar view also suggested that overall, the API (based on particulate matter) in 2014 was much better as compared to 2015.

MEDA HS: Relative humidity sensor for the Mars 2020 Perseverance rover

The Finnish Meteorological Institute (FMI) provides a relative humidity measurement sensor (HS) for NASA's Mars 2020 rover. The sensor is a part of the Mars Environmental Dynamic Analyzer (MEDA), a suite of environmental sensors provided by Spain's Centro de Astrobiología. The main scientific goal of the humidity sensor is to measure the relative humidity of the Martian atmosphere near the surface and to complement previous Mars mission atmospheric measurements for a better understanding of Martian atmospheric conditions and the hydrological cycle. Relative humidity has been measured from the surface of Mars previously by Phoenix and Curiosity. Compared to the relative humidity sensor on board Curiosity, the MEDA HS is based on a new version of the polymeric capacitive humidity sensor heads developed by Vaisala. Calibration of humidity devices for Mars conditions is challenging and new methods have been developed for MEDA HS. Calibration and test campaigns have been performed at the FMI, at University of Michigan and the German Aerospace Center (DLR) in Berlin to achieve the best possible calibration. The accuracy of HS and uncertainty of the calibration has been also analysed in detail with VTT Technical Research Centre of Finland. Assessment of sensor performance after landing on Mars confirms that the calibration has been successful, and the HS is delivering high quality data for the science community.

Low-cost inkjet-printed humidity sensor using nanoporous surface on coated paper

The present work describes the behaviour of nanoporous structure on two coated papers for determining their suitability for relative humidity measurement. We found that the paper with smaller pore size was better in terms of response and relative humidity range. The nanoporous inorganic thin film with high surface to volume ratio is better to detect the presence of water molecules in the environment. The hydrophilic nature of the surface coating is thus found more active compared to cellulosic paper for sensing water vapour. Prototype sensors made by us responded to the whole range of 15%− 92% RH by combining the resistance and capacitance variations of the interdigitated electrode. The resistance variations provided better response over the range of 15%− 55% RH whereas capacitance variation was better in 55%− 92% RH. The novelty of the present work is using nanocoated papers which are low cost and bio-degradable for field applications.

Athermal Microwave Photonic Sensor Based on Single Microring Resonance Assisted by Machine Learning

We propose a machine learning (ML) assisted athermal microwave photonic (MWP) sensing scheme with high resolution based on a single microring resonance. The immunity of temperature interference of the high-resolution sensing is achieved by employing MWP sideband processing based interrogation, and supervised machine learning based on support vector regression (SVR) and neural tangent kernel (NTK) that are effective on small datasets. The MWP sideband processing transforms the variation of the target measurand into the shift of an ultra-deep notch in the radio frequency (RF) spectrum relieving the fabrication requirements on the microresonators, while ML accurately predicts the measurand by using the modulator bias voltage or RF passband transmission together with the RF notch position. The proposed sensor is demonstrated for relative humidity (RH) measurements using a silicon-on-insulator microring coated with polymethyl methacrylate. About 50 dB high RF rejection ratio is achieved over the sensing process, indicating a high sensing resolution. Despite the small experimental datasets, the established SVR and NTK models consistently exhibit lower mean absolute errors (MAEs) than the linear regression model in the RH prediction in the presence of temperature drifts. The NTK models achieve the lowest MAEs of 1.01% RH and 1.03% RH when the RF passband transmission and modulator bias are selected as the model input, respectively. The equivalent performances of the RF passband transmission and modulator bias voltage further demonstrate the feasibility of athermal sensing based solely on the MWP interrogation results of a single microring resonance, which simplifies the design and reduces the complexity.

Design and Fabrication of a Robust Chitosan/Polyvinyl Alcohol-Based Humidity Sensor energized by a Piezoelectric Generator

Due to their rapid growth in industrial and environmental applications, there is a need to develop self-powered humidity sensor systems with improved sensitivity, a wide detection range, and an eco-friendly nature. In this study, an aqueous solution of chitosan (CS) and polyvinyl alcohol (PVA) was blended to yield a composite film material with enhanced humidity detection properties. Meanwhile, a polyvinylidene difluoride (PVDF)-loaded chitosan composite film was developed and employed as a piezoelectric generator. Moreover, the developed composite materials for both devices (the piezoelectric generator and the humidity sensor) were optimized based on output performance. The piezoelectric generator generates a maximum of 16.2 V when a force of 10 N is applied and works as a power source for the humidity-sensing film. The sensing film swells in response to changes in relative humidity, which affects film resistance. This change in resistance causes a change in voltage through the piezoelectric generator and allows the precise measurement of relative humidity (RH). The fabricated sensor showed a linear response (R2 = 0.981) with a reasonable sensitivity (0.23 V/% RH) in an environment with an RH range of 21–89%. In addition, the device requires no external power, and therefore, it has numerous sensing applications in various fields.

The experimental study of dehumidification and regeneration processes in a fin and tube liquid desiccant system

Significant focus has been placed on improving Indoor Air Quality (IAQ) due to the emergence of the large-scale severe acute respiratory syndrome (SARS) virus epidemic in the air conditioning system of buildings. There is also a need for an adequate air ventilation system that balances energy needs with air quality. This led to the discovery of liquid desiccants which have the ability to enhance air quality and lower primary energy usage as an alternative to the standard air dehumidification technology. Therefore, this study was conducted to investigate the dehumidification and regeneration processes in a Fin and tube liquid desiccant system. This involved flowing air horizontally while the ionic liquid flowed through the cooling or heating coil vertically downward to create a cross-flow fin and tube configuration. In the testing process, we obtained measurements of relative humidity and dry bulb temperature inlet and outlet from ducting by varying the input parameters. Moreover, the differential humidity ratio of the inlet and output process for the dehumidification and regeneration was observed to be essential for the dehumidifier performance indices. The experimental result showed that the system absorbed a humidity ratio of 5.5 g/kg during the dehumidification process and released 10.7 g/kg during regeneration.

A fully distributed fiber optic sensor for simultaneous relative humidity and temperature measurement with polyimide-coated polarization maintaining fiber

A distributed fiber-optic sensor for simultaneous relative humidity (RH) and temperature measurement is proposed and experimentally demonstrated by means of optical frequency domain reflectometry (OFDR) with single sensing fiber configuration. The sensing element is a high-birefringence polarization-maintaining (HB-PM) fiber with polyimide coating that transfers strains on the fiber after being expanded by water uptake with the ambient RH changes. Either humidity-variation-induced strain applied on the fiber or temperature changes contribute to distinct spectral responses in the cross-correlation and auto-correlation results of Rayleigh backscatter signals from the polyimide-coated HB-PM sensing fiber when interrogated by the OFDR technique. These spectral responses can be successfully extracted for every segment of the sensing fiber with a centimeter-order spatial resolution, enabling distributed temperature and RH discriminative measurement along the sensing fiber. Experimental results show that the optimal sensitivities for RH and temperature measurement can reach up to 1.8 pm/%RH and 11.1 pm/°C, respectively. Measurement errors for simultaneous RH and temperature sensing are found to be 0.54 °C and 2.75%RH, respectively. The proposed sensing technique will open a brand-new door for developing reliable and practical distributed RH and temperature discrimination sensing systems with high sensitivities and low errors.

The actual performance of retrofitted residential apartments: post-occupancy evaluation study in Italy

ABSTRACT Housing retrofits are undertaken to reduce energy use and to improve ‘occupants’ indoor environmental conditions. Despite increased retrofitting of the Italian housing stock, there is a lack of data on their energy use and indoor environmental quality (IEQ). This paper fills this gap by a post-occupancy evaluation (POE) study of seven retrofitted apartments in northern Italy; a non-retrofitted case study was included as a comparison. The study aimed to understand aspects of IEQ and occupant satisfaction after energy-efficiency retrofits. A mixed-method approach encompassed occupant satisfaction surveys, energy bill comparisons, in-situ indoor air temperature, and relative humidity measurements. Results highlighted ‘occupants’ thermal comfort improvement and heating energy consumption reduction after retrofits. Furthermore, reported preferred indoor temperatures w within a broader range than the recommended Italian regulations and CIBSE guide A standard. However, some participants reported unintended consequences, including mould growth and noise from the mechanical ventilation system. This study shows the potential of POE to understand the actual performance of retrofitted residential buildings. However, the difficulties of conducting a POE in retrofitted existing residential buildings show the need of further research on how to effectively conduct POE in retrofitted residential buildings, including improved digital quality monitoring methods.

A Parallel Optical Fiber Fabry–Perot Interferometer for Simultaneous Measurement of Relative Humidity and Temperature

A parallel optical fiber Fabry–Perot interferometer (FPI) and Vernier effect sensor for simultaneous high-sensitivity measurement of relative humidity (RH) and temperature is proposed and verified by experiments. Two sections of a single-mode fiber (SMF) are fixed on the precision displacement platform, aligning them and leaving a small gap between them, and then filling the gap with polydimethylsiloxane (PDMS) and polyimide (PI), respectively, to form two Fabry–Perot (F–P) cavities. To produce a Vernier effect when two F–P cavities are connected in parallel, the length of two F–P cavities must be accurately controlled to ensure that the free spectral range (FSR) of the two F–P cavities is similar. It is found that the F–P cavity filled with PI is sensitive to RH and temperature, while the F–P cavity filled with PDMS is only sensitive to temperature. Due to the different characteristics of the two F–P cavities, the simultaneous measurement of RH and temperature is realized by constructing the sensitivity measurement matrix. If they are connected in parallel to produce the Vernier effect, the RH and temperature sensitivities of the parallel structure can reach −11.388 nm/%RH and 18.436 nm/°C, respectively. The sensor has potential applications in the fields of biopharmaceuticals, environmental monitoring, food processing, and microbial sensing.

Construction of multiple anti-resonant light guidance mechanisms in a hollow-core fiber structure for simultaneous measurement of multiple parameters.

The construction of multiple light guidance mechanisms in a hollow-core fiber (HCF) structure is a popular way to realize the simultaneous measurement of multiple parameters. In this work, a partial coating method to excite multiple anti-resonant light guidance mechanisms (ARLGMs) in an HCF structure for the simultaneous measurement of multiple parameters is proposed. As an example, a double ARLGM based on a partially polyimide (PI)-coated HCF structure for the simultaneous measurement of relative humidity (RH) and temperature is demonstrated theoretically and experimentally. The dip (dip II) produced by the PI-coated HCF section shifts linearly with surrounding RH changes with a sensitivity of circa 58.6 ± 0.77 pm/%RH, while the dip (dip I) produced by the bare HCF section (with an air coating layer) is insensitive to RH changes. In addition, both types of dips have linear responses to temperature variations, with similar sensitivities of ∼ 17 pm/°C. Hence, the proposed sensor structure can be used as an RH sensor that is also capable of compensating for local temperature fluctuations. More importantly, the simultaneous measurement of multiple parameters (such as biomarkers) is possible using the proposed method provided the proper sensing materials are partially coated onto the HCF surface.