Relative Humidity Monitoring Research Articles

Compact readout system for chipless passive LC tags and its application for humidity monitoring

The development of a contactless readout system for High Frequency (HF) tags and its application to relative humidity monitoring is presented. The system consists of a Colpitts oscillator circuit whose frequency response is determined by a built-in logic counter of a microcontroller unit. The novel readout strategy is based on the frequency response change due to the inductive coupling between the coil of the Colpitts oscillator and the load impedance of a parallel LC resonator tag, as a result of the variation of the humidity sensing capacitor. The frequency is monitored with a low cost microcontroller, resulting in a simple readout circuit. This passive LC tag has been directly screen-printed on a humidity-sensitive flexible substrate. The readout circuit experimental uncertainty as frequency meter was 4 kHz in the HF band. A linear temperature drift of (-1.52 ± 0.17) kHz/⁰C was obtained, which can be used to apply thermal compensation if required. The readout system has been validated as a proof of concept for humidity measurement, obtaining a significant change of about 260 kHz in the resonance frequency of the Colpitts oscillator when relative humidity varies from 10% to 90%, with a maximum uncertainty of ±3% (±2 SD). Therefore, the proposed readout system stands as a compact, low-cost, contactless solution for chipless HF tags that avoids the use of bulky and costly equipment for the analog reading of wireless passive LC sensors.

The capability of capacitive sensors in the monitoring relative humidity in hypogeum environments

Hypogeum environments are characterized by high levels of relative humidity (RH). Most humidity sensors currently in use are based on the capacitive effect of the dielectric material to change according to water vapour uptake. In hypogeum environments the dielectric material can be saturated by water vapor, implying a significant error in the RH measurement. To improve the capacity of this type of humidity sensors, a modified hygrometer capacitive sensor, which uses a heating cycle to avoid the condensation, has been recently developed by Rotronic®. During four field campaigns in two different hypogea environments (the Monkey Tomb in Siena and the Mithreum of Caracalla Baths in Rome), RH was measured using the conventional capacitive sensor (CCS) and the heated capacitive sensor (HCS). The purpose of this study was to investigate the capability of HCS to detect RH variations when the environmental conditions were close to vapor saturation. Significant differences were found between the measurements of the two sensors: when RH was close to 100%, the CCS was not able to detect the RH decrease, giving only a measure of RH=100%, while HCS detected such a RH decrease. Therefore, these results encourage the use of HCS in the monitoring of RH levels in extreme humidity sites such as hypogea sites.

Determination of thermal preferences based on event analysis

Real thermal preferences of occupants are rarely considered by the automatic control of HVAC systems. It is due to difficulties in describing satisfactory thermal conditions, especially when opinion of many people has to be taken into account. This work presents a method which allows to determine the preferred temperature and the associated relative humidity for a group of occupants in the room equipped with a manually controlled local cooling/heating system. It was assumed that thermal preferences of the group are reflected in the way they operate such system. The method is based on the continuous monitoring of air temperature and relative humidity and the detection of events. An event is defined by the time period between succeeding adjustments of the heating/cooling device. During events, temperature and relative humidity behave in a characteristic manner. Patterns of their periodic variation were determined using Discrete Fourier Transform and used for the detection of events. The preferred temperature can be derived from the descriptive statistics of temperature during detected events. The method was developed and calibrated for an air conditioned office. The relevant data was collected during summer period. The analysis showed that the method is successful in retrieving the preferred temperature and it is less effective in reproducing the preferred temperature range. Events were more accurately detected when using patterns of temperature variation (false negative detection rate was 14.00% and false positive detection rate was 4.44%) compared with patterns of variation of relative humidity. The approach is computationally efficient and after calibration, it may be directly applied to evaluate local thermal preferences.

An inverse analysis approach for the identification of the hygro-thermo-chemical model parameters of concrete

Hygro-thermo-chemical models provide useful representations of the mechanisms of moisture transport and temperature variations that take place in concrete structures and that can influence their durability and service behaviour. Several material parameters need to be specified when performing a hygro-thermo-chemical simulation. While some of these parameters can be evaluated based on the concrete mix specifications or from data reported in the literature, some other parameters are not readily available from the literature, partly because of their large variability and partly because they do not possess a precise physical meaning. In this context, this paper presents a robust inverse analysis procedure for the identification of this latter set of material parameters. The inverse analysis problem is formulated by using temperature and relative humidity profiles taking place within a concrete component as input. The proposed approach is applied to evaluate the minimum number of temperature and relative humidity measurements that are necessary to be performed for a successful identification of the sought material parameters. Representative results of an extensive sensitivity analysis are presented to gain insight into the most effective locations within the concrete component for the measurements and instants in time when these measurements should be collected. The inverse analysis procedure is then presented and validated against a set of pseudo-experimental results affected by different levels of noise, highlighting the robustness of the proposed methodology when applied with the arrangements suggested in terms of discrete relative humidity and temperature measurements and monitoring periods.

Optical fiber sensors based on novel polyimide for humidity monitoring of building materials

Abstract This paper presents novel preparation methods of polyimide and coupling agent, coated on the fiber Bragg grating (FBG) sensor for monitoring relative humidity (RH). The sensing mechanism that the volume change of the moisture-sensitive polyimide induces the shift of the Bragg wavelength of FBG is used in the RH sensor. The performance of the polymer-coated RH sensor was evaluated under laboratory conditions of temperature over a range of values (20.0–80.0 °C) and humidity over a range of RH values (25.0–95.0%). The time response and RH sensitivity of the sensor based on novel polyimide and coupling agent was improved, compared to the previous. A new packaged RH sensor was designed, which was used in detecting the moisture diffusion and evolutions inside of sample made of building materials which exposed to a controlled environment in the lab after casting. Relative humidity inside of sample with time was 100% in the first phase of vapor-saturated, slowly reduced in the latter phase. The results indicate the RH sensor developed provides a feasible method to detect the influence of environment on moisture inside the material in the drying process.

Uncertainty in the measurement of indoor temperature and humidity in naturally ventilated dairy buildings as influenced by measurement technique and data variability

The microclimatic conditions in dairy buildings affect animal welfare and gaseous emissions. Measurements are highly variable due to the inhomogeneous distribution of heat and humidity sources (related to farm management) and the turbulent inflow (associated with meteorologic boundary conditions). The selection of the measurement strategy (number and position of the sensors) and the analysis methodology adds to the uncertainty of the applied measurement technique. To assess the suitability of different sensor positions, in situations where monitoring in the direct vicinity of the animals is not possible, we collected long-term data in two naturally ventilated dairy barns in Germany between March 2015 and April 2016 (horizontal and vertical profiles with 10 to 5 min temporal resolution). Uncertainties related to the measurement setup were assessed by comparing the device outputs under lab conditions after the on-farm experiments. We found out that the uncertainty in measurements of relative humidity is of particular importance when assessing heat stress risk and resulting economic losses in terms of temperature-humidity index. Measurements at a height of approximately 3 m–3.5 m turned out to be a good approximation for the microclimatic conditions in the animal occupied zone (including the air volume close to the emission active zone). However, further investigation along this cross-section is required to reduce uncertainties related to the inhomogeneous distribution of humidity. In addition, a regular sound cleaning (and if possible recalibration after few months) of the measurement devices is crucial to reduce the instrumentation uncertainty in long-term monitoring of relative humidity in dairy barns.

Carbon-nanotube / Polyvinyl alcohol coated thin core fiber sensor for humidity measurement

A Carbon-nanotube (CNT)/Polyvinyl alcohol (PVA) composite film-coated thin core fiber (TCF) optics sensor is proposed for monitoring relative humidity (RH). The unique Michelson type fiber interferometer sensor consists a short segment of TCF, the tip of which is melted into a convex shape and coated with a hydroscopic CNT/PVA film. The proposed sensor is linearly responsive to relative humidity (RH) beyond the humidity range 70%RH, with maximum sensitivity of −0.4573dB/%RH. The advantages of this sensor are its compact size, excellent stability and facile fabrication process.

ESTUDO SENSORIAL E FÍSICO-QUÍMICO DE VEGETAIS ARMAZENADOS EM REFRIGERAÇÃO COM MONITORAMENTO DE PARÂMETROS

O controle da temperatura e da umidade relativa em sistemas de refrigeração, para armazenamento de alimentos frescos, é fundamental para garantir boa aparência e manter as características físico-químicas, biológicas e sensoriais por períodos mais longos. Já que estes parâmetros afetam diretamente os atributos de qualidade nutricional, textura, aroma, sabor e aspecto visual. O objetivo deste trabalho foi avaliar o impacto da temperatura do sistema de refrigeração isotérmico (3,3°C) e o monitoramento da umidade relativa na vida de prateleira dos vegetais (melancia, melão, aspargos, milho, ervilha, pimentão, aipo, pepino e alface romana). Foram realizadas análises da variação da massa, sensoriais e de cor com todos estes vegetais durante os 12 dias de armazenamento refrigerado. A análise sensorial foi realizada por um painel de sete julgadores treinados que avaliaram as amostras em uma escala hedônica não estruturada de nove pontos. De acordo com a avaliação sensorial, os alimentos foram rejeitados na seguinte ordem: ervilha torta no terceiro dia; milho no quarto dia; alface romana no quarto dia; pepino no sexto dia; aipo no oitavo dia; melancia no nono dia; melão no 11° dia; aspargos no 11° dia e pimentão verde no 12° dia.

PMMA microfiber loop resonator for humidity sensor

A PMMA microfiber loop resonator (PMLR) coated with zinc oxide (ZnO) nanostructure is proposed and demonstrated for the monitoring of relative humidity. The PMLR has a loop diameter of 56μm and was fabricated using direct drawing technique using a 6μm diameter PMMA microfiber. The results showed an increase in the sensitivity of the sensor with the additional coating of ZnO nanostructure on the surface of the PMMA fiber. The working mechanism of the device is based on the observed decrement in the transmission of the sensor that was carefully placed in a sealed chamber. As the relative humidity level varies from 20% to 80%, the output power of the PMLR with ZnO nanostructure coating decreases linearly from −9.57dBm to −20.19dBm with a maximum sensitivity, linearity and resolution of 0.1746dBm/%, 94% and 6.17%, respectively. This work is highly beneficial as it combines the high sensitivity obtained by using traditional silica fibers but with the ruggedness and flexibility of PMMA fibers, making them highly suitable for continuous monitoring of relative humidity in compact areas.

Fiber Bragg Grating Measuring System for Simultaneous Monitoring of Temperature and Humidity in Mechanical Ventilation.

During mechanical ventilation, the humidification of the dry air delivered by the mechanical ventilator is recommended. Among several solutions, heated wire humidifiers (HWHs) have gained large acceptance to be used in this field. The aim of this work is to fabricate a measuring system based on fiber Bragg grating (FBG) for the simultaneous monitoring of gas relative humidity (RH) and temperature, intended to be used for providing feedback to the HWHs’ control. This solution can be implemented using an array of two FBGs having a different center wavelength. Regarding RH monitoring, three sensors have been fabricated by coating an FBG with two different moisture-sensitive and biocompatible materials: the first two sensors were fabricated by coating the grating with a 3 mm × 3 mm layer of agar and agarose; to investigate the influence of the coating thickness to the sensor response, a third sensor was developed with a 5 mm × 5 mm layer of agar. The sensors have been assessed in a wide range of RH (up to 95%) during both an ascending and a subsequent descending phase. Only the response of the 3 mm × 3 mm-coated sensors were fast enough to follow the RH changes, showing a mean sensitivity of about 0.14 nm/% (agar-coated) and 0.12 nm/% (agarose-coated). The hysteresis error was about <10% in the two sensors. The contribution of temperature changes on these RH sensors was negligible. The temperature measurement was performed by a commercial FBG insensitive to RH changes. The small size of these FBG-based sensors, the use of biocompatible polymers, and the possibility to measure both temperature and RH by using the same fiber optic embedding an array of two FBGs make intriguing the use of this solution for application in the control of HWHs.

Zeonex-PMMA microstructured polymer optical FBGs for simultaneous humidity and temperature sensing.

In this Letter, we report for the first time, to the best of our knowledge, the fabrication and characterization of a Zeonex/PMMA microstructured polymer optical fiber (mPOF) Bragg grating sensor for simultaneous monitoring of relative humidity (RH) and temperature. The sensing element (probe) is based on two separate in-line fiber Bragg gratings (FBGs) inscribed in the fabricated mPOF. A root mean square deviation of 0.8% RH and 0.6°C in the range of 10%-90% RH and 20°C-80°C was found. The developed mPOFBG sensor constitutes an efficient route toward low-cost, easy-to-fabricate and compact multi-parameter sensing solutions.

Investigation of Indoor Environment Quality in Classroom - Case Study

The experimental monitoring of indoor air temperature, relative humidity, and carbon dioxide were carried out for the investigation of real state of the indoor environment in selected classrooms during winter and summer semester. Concurrently subjective evaluation by questionnaire was conducted. The average value of indoor air temperature was 23.1°C, relative humidity 41.15% and CO2 concentration 1315.88ppm in winter semester. The average value of indoor air temperature was 24.8°C, relative humidity 36.28% and CO2 concentration 1094.62ppm in summer semester. Results of objective and subjective assessment show that it is important to propose optimization measures for reducing the CO2concentrations and thermal load in summer period.

On the Modeling of Air Flow in the Tombs of the Valley of Kings

The tombs of the kings in Valley of the Kings, Luxor, are considered to be one of the tourism industry’s bases in Egypt due to their uniqueness all over the world. Hence, they should be preserved from the different factors that might cause harm for their wall paintings. One of these factors is the excessive relative humidity as it increases the bacteria and fungus activity inside the tomb in addition to its effect on the mechanical and physical properties of materials. This chapter describes the Research work to design ventilation systems to some of these important tombs. The chapter aims to investigate, design, and implement controlled climate to the tombs of the valley of kings with complete monitoring of air properties, temperature, relative humidity and carbon oxides and air quality parameters mechanical distributions inside selected tombs of the valley of the kings that are open for visitors. A complete climate control and monitoring of air will be effected with the aid of a mechanical ventilation system extracting air at designated locations in the wooden raised floor of the tombs. The location, size and extracted air are to be predicted and optimized the use of Computational Fluid Dynamics software (CFD). The CFD modelling techniques would solve the continuity, momentum, energy, and species transport equations in addition to k-epsilon model equations for turbulence closure. The SIMPLEC algorithm is used for the pressure-velocity coupling and a second order upwind scheme was use for discretization of the governing equations. Mesh sizes used in the present work exceeded 700,000 mesh volumes to adequately represent the flow characteristics at various locations. Throughout the first phase of this investigation, the outside air conditions, number of visitors, and airside system design effect on the tombs’ airflow characteristics will be studied in order to reach the optimum ventilation design as well as the favourable working conditions for a particular tomb. Mechanical engineering design of air flow system including under raised floor flexible duct routings, sizes, grills locations etc. with be provided in professional design drawing to be used as bases for execution and installation at the second phase. A complete set of measuring and monitoring equipment will be installed for each tomb to intelligently direct the visitors to the tomb where relative humidity and CO2 levels are permissible. A permissible number of the simultaneous of visitors for each tomb should be made in order to limit the relative humidity inside any given tomb.

A PMMA microfiber loop resonator based humidity sensor with ZnO nanorods coating

Abstract A Polymethyl methacrylate (PMMA) microfiber loop resonator (PMLR) coated with zinc oxide (ZnO) nanorods is proposed and demonstrated for the monitoring of relative humidity (RH) of the surrounding air. Relative humidity refers to the amount of moisture in the air relative to the total amount of moisture that the air can contain. The PMLR has a loop diameter of 42 μm and was fabricated using a direct drawing technique using an 8 μm diameter PMMA microfiber. The results showed an increase in the sensitivity of the sensor with the additional coating of the ZnO nanorods on the surface of the PMMA fiber. The working mechanism of the device is based on the observed increment in the transmission of the sensor that was carefully placed in a sealed chamber. As the relative humidity level increases from 50%RH to 80%RH, the output power of the PMLR with ZnO nanorods coating decreases linearly from −37.77 dBm to −52.99 dBm with a maximum sensitivity, linearity and resolution of 0.5221 dBm/%RH, more than 99% and 0.4094%RH, respectively. This work is highly beneficial as it combines the high sensitivity of traditional silica fibers with the ruggedness and flexibility of PMMA fibers, making them highly suitable for continuous monitoring of relative humidity in compact areas.

Thermal Assessment of Traditional, Partially Subterranean Dwellings in Coastal and Mountainous Regions in the Mediterranean Climate. The Case of Cyprus

Fully, or partially, subterranean dwellings have developed as a distinctive building type from the prehistoric to pre-industrial era in the Mediterranean region, often serving specific purposes. The energy benefits of such spaces are well documented mainly through the investigation of numerous examples found in vernacular architecture. Despite their environmental potentials, subterranean structures remain limited in contemporary design practices. The present paper reports on the findings of a systematic research that examines partially subterranean traditional dwellings in the coastal and mountainous regions of Cyprus, an island in the Eastern Mediterranean. The study focuses on the environmental assessment of these spaces, through the monitoring of air temperature and relative humidity, and on a brief demonstration of various passive strategies for indoor microclimate improvements. Although these structures are not very common in the vernacular architecture of the island, their scientific examination produces useful knowledge in terms of energy savings. This can inform contemporary design applications and form a basis for the drafting of environmental refurbishment guidelines, applicable for this particular building typology. The research indicates favourable temperatures and significant cooling effects in partially subterranean spaces during the hot summer period, especially in mountainous regions. Temperatures in such spaces during the cold winter period are found to exhibit higher values compared to the temperatures of above-ground spaces, although they remain below comfort limits. High indoor humidity is found to be a major problem, in both the summer and winter period, in the coastal regions of the island. It is highlighted that, although partially subterranean spaces have many environmental benefits, as earth offers thermal insulation and heat storage, generalizations should be avoided since a number of varying parameters, such as the local climate, geology, natural ventilation conditions and building materials used, influence considerably their environmental performance.DOI: http://dx.doi.org/10.5755/j01.sace.16.3.16155

Indoor relative humidity as a fire risk indicator

A low cost weather station has been tested for monitoring relative humidity (RH) in sitting rooms as a dry wood fast fire development risk indicator. Ten Norwegian wooden homes/flats, built between 1843 and 2012, were selected for testing during the winter 2015/2016. Linear calibration curves for each in- and outdoor sensor, based on saturated inorganic salt solution controlled air, were needed to ensure ±3% RH accuracy. Recorded average moisture supply to the indoor air during the winter varied from 0.30 to 2.64 g/m3, with mean 1.29 ± 0.75 g/m3. The oldest buildings and the modern balanced ventilation buildings were generally driest. A near step change to drier weather in January resulted in a 6–7 days decay period for recorded indoor RH of the older buildings with wood panel wall linings. This was within reasonable proximity (30%) of theoretically expected step change diffusion controlled wood panel drying. The decay period was shorter for a modern building with plasterboard wall linings. A similarly long decay period was not observed for subsequent rising RH values two weeks later. This discrepancy may be explained by wood desorption adsorption hysteresis. The calibrated weather stations gave reliable results throughout the winter season. They served, and may very well also in the future serve, as detectors for warning local fire brigades about emerging dry wood fire risk situations. Due to hysteresis, more research is, however, needed to know when to call off a dry indoor climate high fire risk condition as the conditions gets less dry.

ARCHIVAL PRESERVATION PRACTICES AT THE RECORDS AND ARCHIVES MANAGEMENT DEPARTMENT IN TANZANIA

The aim of this study was to assess preservation practices at the Records and Archives Management Department (RAMD) in Tanzania and to make recommendations aimed at ensuring the long-term preservation and accessibility of archives held at RAMD. The population of the study consisted of the Director of RAMD, two Assistant Directors, ten Senior Records Officers, two Records Officers, three Senior Records Management Assistants, three Principal Records Management Assistants and one Records Management Assistant. The data collection instruments included questionnaires, interviews, observation and content analysis. Qualitative data analysis was used to gain a better understanding of the issues under investigation. The findings indicated that legislation relating to the preservation of archives in Tanzania is not comprehensive enough and that RAMD lacks a preservation policy; preserves only paper-based materials; experiences a shortage of storage equipment; holds records under poor environmental conditions; lacks proper archival handling; carries out inadequate housekeeping practices; lacks adequate security and disaster preparedness measures; has inadequate conservation and restoration facilities; is underfunded; and lacks trained and experienced conservators. The study recommends amendments to the Records and Archives Management Act No. 3 of 2002; the formulation of a conservation policy; improvements in housekeeping practices and handling practices; and effective monitoring of temperature and relative humidity.

Investigation of strain induced effect on linear shape fiber Bragg grating embedded in composite material

In this work experimental results are presented of strain induced effects on a linear shape fiber Bragg grating embedded in a composite material. Mechanical analysis of the composite material has been numerically performed by using commercially available software Ansys. Advanced Bragg gratings make it possible to simplify detection systems, calibration process of fiber optic sensors and quasi &ndash; spot metering. Full Text: PDF References P. Kisała, "Optoelectronic sensor for simultaneous and independent temperature and elongation measurement using Bragg gratings", Przegląd Elektrotechniczny 11a, 343 (2012). DirectLink X. Wen, D. Zhang, Y. Qian, J. Li, N. Fei, "Improving the peak wavelength detection accuracy of Sn-doped, H2-loaded FBG high temperature sensors by wavelet filter and Gaussian curve fitting", Sensors Actuat. A: Phys. 174, 91 (2012). CrossRef H. Peng, Y. Su, Z. Ye, B. Zhou, "A novel fiber Bragg grating sensor for weak pressure measurement based on the Stokes parameter", Opt. Fiber Technol. 18(6), 485 (2012). CrossRef G. Luyckx, E. Voet, N. Lammens, J. Degrieck, "Strain Measurements of Composite Laminates with Embedded Fibre Bragg Gratings: Criticism and Opportunities for Research", Sensors 11, 384 (2011). CrossRef S. Yashiro, N. Takeda, T. Okabe, H. Sekine, "A new approach to predicting multiple damage states in composite laminates with embedded FBG sensors", Composites Science Technol. 65, 659 (2005). CrossRef Y. Zhan, L. Li, F. Yang, K. Gu, H. Wu, M. Yu, "An all-fibre multi-parameter sensor for composite structures based on a chirped fibre Bragg grating", Opto-Electron. Rev. 21(3), 283 (2013). CrossRef Y. Okabe, R. Tsuji, N. Takeda, "Application of chirped fiber Bragg grating sensors for identification of crack locations in composites", Composites: Part A 35, 59 (2004). CrossRef S. Yashiro, T. Okabe, N. Toyama, N. Takeda, "Monitoring damage in holed CFRP laminates using embedded chirped FBG sensors", Intern. J. Solids Structur. 44, 603 (2007). CrossRef C. Fernandez-Valdivielso, I.R. Matoas, F.J. Arregui, "Simultaneous measurement of strain and temperature using a fiber Bragg grating and a thermochromic material", Sensors Actuat. A: Phys. 101, 107 (2002). CrossRef A. Makovec, G. Berruti, M. Consales, M. Giordano, P. Petagna, S. Buontempo, G. Breglio, Z. Szillasi, N. Beni, A. Cusano, "Radiation hard polyimide-coated FBG optical sensors for relative humidity monitoring in the CMS experiment at CERN", J. Instrumentation 9(3), C03040 (2014). CrossRef P. Kisała, "Detection of material defects with indirect metod by determining the linear expansion with FBG sensor", Przegląd Elektrotechniczny, NR 1a, R. 89, 29 (2013). DirectLink A. Papantoniou, G. Rigas, N.D. Alexopoulos, "Assessment of the strain monitoring reliability of fiber Bragg grating sensor (FBGs) in advanced composite structures", Composite Structur. 93, 2163 (2011). CrossRef Y. Okabe, R. Tsuji, N. Takeda, "Application of chirped fiber Bragg grating sensors for identification of crack locations in composites", Composites: Part A 35, 59 (2004). CrossRef P.Lesiak, M.Szeląg, D.Budaszewski, R.Plaga, K.Mileńko, G.Rajan, Y.Semenova, G.Farrell, A.Boczkowska, A.Domański, T.Woliński, Influence of lamination process on optical fiber sensors embedded in composite material", Measurement, Vol. 45, Issue 9, November 2012, Pages 2275&ndash;2280. CrossRef P. Lesiak, M. Szeląg, K. Mileńko, T. Woliński, A. Domański, K. Jędrzejewski, A. Boczkowska, "Polarimetric and Bragg Optical Fiber Sensors for Stress Distribution and Temperature Measurements in Composite Materials", Acta Phys. Polonica A 120, 698 (2011). CrossRef A.W. Domański, P. Lesiak, K. Milenko, A. Boczkowska, D. Budaszewski, S. Ertman, T.R. Woliński, "Temperature-insensitive fiber optic deformation sensor embedded in composite material", Photon. Lett. Poland 1(3), 121 (2009). CrossRef

To Study the Temporal Variation of Capacity Utilization Factor (CUF) of PV Based Solar Power Plant with Respect to Climatic Condition

Performance, quality and reliability of technology are becoming more and more important for the emerging photovoltaic markets worldwide. In this experiment the monitoring of climatic factors like, solar radiation, Ambient Temperature, Module Temperature, Relative Humidity and Wind Speed was carried out on daily basis for six months, between 7:00 A.M to 6:00 P.M. Data was measured with SCADA system. This analysis was carried out by monitoring the fluctuation in power output of the system with climatic factors. From the results, there is direct proportionality between the power output of the system and the climatic factors. The correlation between ambient air temperature, PV module temperature and CUF is strongly positive. The other climatic factor like wind speed is does not have much significant effect on CUF. The Relative humidity is negatively correlated with CUF. The correlation between solar radiation and the CUF is strongly positive.

Wheat gluten, a bio-polymer layer to monitor relative humidity in food packaging: Electric and dielectric characterization

Thin wheat gluten protein film, largely investigated as eco-friendly material for food packaging, is investigated as a relative humidity monitoring polymer deposited on designed and manufactured interdigital capacitor (IDC) systems, on the frequency range from 30MHz to 1000MHz. The ability of wheat gluten to interact with water molecules was characterized and assessed in terms of electrical and dielectric properties with the IDC technique. When relative humidity increases from 20% to 95% RH at 25°C, the dielectric permittivity and loss change from 5.01±0.04 to 9.79±0.06 and from 0.39±0.01 to 1.48±0.02 respectively. The dielectric permittivity and loss are very sensitive to relative humidity and increase exponentially due to the comparable exponential increase of wheat gluten water content versus relative humidity. The accessibility of water molecules and the plasticization of wheat gluten results in an increase in the water absorbed by the protein from 3.6% (at 20% relative humidity) reaching up to 33.6% (at 95% relative humidity) of the dry weight. The dependence of both dielectric permittivity and dielectric loss of wheat gluten on relative humidity offered the possibility to use the protein for monitoring relative humidity in packed food products. For this purpose, wheat gluten is foreseen to be coupled with Ultra High Frequency (UHF) Radio Frequency Identification (RFID) systems, giving a cost-effective, low-energy consuming and reliable solution for traceability and monitoring of food packed products.