Displaying publications 1 - 20 of 189 in total

Abstract:
Sort:
  1. Atnaw SM, Sulaiman SA, Yusup S
    ScientificWorldJournal, 2014;2014:121908.
    PMID: 24578617 DOI: 10.1155/2014/121908
    Biomass wastes produced from oil palm mills and plantations include empty fruit bunches (EFBs), shells, fibers, trunks, and oil palm fronds (OPF). EFBs and shells are partially utilized as boiler fuel while the rest of the biomass materials like OPF have not been utilized for energy generation. No previous study has been reported on gasification of oil palm fronds (OPF) biomass for the production of fuel gas. In this paper, the effect of moisture content of fuel and reactor temperature on downdraft gasification of OPF was experimentally investigated using a lab scale gasifier of capacity 50 kW. In addition, results obtained from equilibrium model of gasification that was developed for facilitating the prediction of syngas composition are compared with experimental data. Comparison of simulation results for predicting calorific value of syngas with the experimental results showed a satisfactory agreement with a mean error of 0.1 MJ/Nm³. For a biomass moisture content of 29%, the resulting calorific value for the syngas was found to be only 2.63 MJ/Nm³, as compared to nearly double (4.95 MJ/Nm³) for biomass moisture content of 22%. A calorific value as high as 5.57 MJ/Nm³ was recorded for higher oxidation zone temperature values.
    Matched MeSH terms: Humidity*
  2. Tripathy A, Pramanik S, Cho J, Santhosh J, Osman NA
    Sensors (Basel), 2014;14(9):16343-422.
    PMID: 25256110 DOI: 10.3390/s140916343
    The humidity sensing characteristics of different sensing materials are important properties in order to monitor different products or events in a wide range of industrial sectors, research and development laboratories as well as daily life. The primary aim of this study is to compare the sensing characteristics, including impedance or resistance, capacitance, hysteresis, recovery and response times, and stability with respect to relative humidity, frequency, and temperature, of different materials. Various materials, including ceramics, semiconductors, and polymers, used for sensing relative humidity have been reviewed. Correlations of the different electrical characteristics of different doped sensor materials as the most unique feature of a material have been noted. The electrical properties of different sensor materials are found to change significantly with the morphological changes, doping concentration of different materials and film thickness of the substrate. Various applications and scopes are pointed out in the review article. We extensively reviewed almost all main kinds of relative humidity sensors and how their electrical characteristics vary with different doping concentrations, film thickness and basic sensing materials. Based on statistical tests, the zinc oxide-based sensing material is best for humidity sensor design since it shows extremely low hysteresis loss, minimum response and recovery times and excellent stability.
    Matched MeSH terms: Humidity*
  3. How YF, Lee CY
    J Med Entomol, 2010 Nov;47(6):987-95.
    PMID: 21175045
    The effect of temperature and humidity on the survival and water loss of the tropical bed bug, Cimex hemipterus (F.), was studied using two field-collected strains. Insects were exposed to temperatures ranging from 20 to 45 degrees C and relative humidities (RHs) of 33, 75, and 100%. C. hemipterus survived longest under the interaction of low temperature (20 degrees C) and high RH (75-100%). Survival and water loss were significantly affected (P < 0.01) by temperature and RH (either singly, or in interaction). Strain and sex significantly (P < 0.01) influenced bed bug survival, but not on water loss. Eggs, first instars, and adults reached their upper thermal lethal limit within 1 h at 39 degrees C, 44 degrees C, and 46 degrees C, respectively. The survival and water loss profiles showed that starved C. hemipterus started to die after losing 35-45% of their body weights.
    Matched MeSH terms: Humidity*
  4. McDowell N, Allen CD, Anderson-Teixeira K, Brando P, Brienen R, Chambers J, et al.
    New Phytol, 2018 08;219(3):851-869.
    PMID: 29451313 DOI: 10.1111/nph.15027
    Tree mortality rates appear to be increasing in moist tropical forests (MTFs) with significant carbon cycle consequences. Here, we review the state of knowledge regarding MTF tree mortality, create a conceptual framework with testable hypotheses regarding the drivers, mechanisms and interactions that may underlie increasing MTF mortality rates, and identify the next steps for improved understanding and reduced prediction. Increasing mortality rates are associated with rising temperature and vapor pressure deficit, liana abundance, drought, wind events, fire and, possibly, CO2 fertilization-induced increases in stand thinning or acceleration of trees reaching larger, more vulnerable heights. The majority of these mortality drivers may kill trees in part through carbon starvation and hydraulic failure. The relative importance of each driver is unknown. High species diversity may buffer MTFs against large-scale mortality events, but recent and expected trends in mortality drivers give reason for concern regarding increasing mortality within MTFs. Models of tropical tree mortality are advancing the representation of hydraulics, carbon and demography, but require more empirical knowledge regarding the most common drivers and their subsequent mechanisms. We outline critical datasets and model developments required to test hypotheses regarding the underlying causes of increasing MTF mortality rates, and improve prediction of future mortality under climate change.
    Matched MeSH terms: Humidity*
  5. He Z, Chin Y, Yu S, Huang J, Zhang CJP, Zhu K, et al.
    JMIR Public Health Surveill, 2021 01 25;7(1):e20495.
    PMID: 33232262 DOI: 10.2196/20495
    BACKGROUND: The influence of meteorological factors on the transmission and spread of COVID-19 is of interest and has not been investigated.

    OBJECTIVE: This study aimed to investigate the associations between meteorological factors and the daily number of new cases of COVID-19 in 9 Asian cities.

    METHODS: Pearson correlation and generalized additive modeling (GAM) were performed to assess the relationships between daily new COVID-19 cases and meteorological factors (daily average temperature and relative humidity) with the most updated data currently available.

    RESULTS: The Pearson correlation showed that daily new confirmed cases of COVID-19 were more correlated with the average temperature than with relative humidity. Daily new confirmed cases were negatively correlated with the average temperature in Beijing (r=-0.565, P

    Matched MeSH terms: Humidity/adverse effects*
  6. Lim WH, Yap YK, Chong WY, Ahmad H
    Sensors (Basel), 2014;14(12):24329-37.
    PMID: 25526358 DOI: 10.3390/s141224329
    The optical characteristics of graphene oxide (GO) were explored to design and fabricate a GO-based optical humidity sensor. GO film was coated onto a SU8 polymer channel waveguide using the drop-casting technique. The proposed sensor shows a high TE-mode absorption at 1550 nm. Due to the dependence of the dielectric properties of the GO film on water content, this high TE-mode absorption decreases when the ambient relative humidity increases. The proposed sensor shows a rapid response (<1 s) to periodically interrupted humid air flow. The transmission of the proposed sensor shows a linear response of 0.553 dB/% RH in the range of 60% to 100% RH.
    Matched MeSH terms: Humidity
  7. Wong KJ, Johar M, Koloor SSR, Petrů M, Tamin MN
    Polymers (Basel), 2020 Sep 22;12(9).
    PMID: 32971855 DOI: 10.3390/polym12092162
    It is necessary to consider the influence of moisture damage on the interlaminar fracture toughness for composite structures that are used for outdoor applications. However, the studies on the progressive variation of the fracture toughness as a function of moisture content M (%) is rather limited. In this regard, this study focuses on the characterization of mode II delamination of carbon/epoxy composites conditioned at 70 °C/85% relative humidity (RH). End-notched flexure test is conducted for specimens aged at various moisture absorption levels. Experimental results reveal that mode II fracture toughness degrades with the moisture content, with a maximum of 23% decrement. A residual property model is used to predict the variation of the fracture toughness with the moisture content. Through numerical simulations, it is found that the approaches used to estimate the lamina and cohesive properties are suitable to obtain reliable simulation results. In addition, the damage initiation is noticed during the early loading stage; however, the complete damage is only observed when the numerical peak load is achieved. Results from the present research could serve as guidelines to predict the residual properties and simulate the mode II delamination behavior under moisture attack.
    Matched MeSH terms: Humidity
  8. Markus Bulus, Lim, Yaik-Wah, Malsiah Hamid
    MyJurnal
    Scholars have opined that the courtyard is a passive architectural design element and
    that it can act as a microclimate modifier provided that its design requirements are not
    ignored. But despite the assertions, empirical studies on the microclimatic
    performance of a fully enclosed courtyard house and the non-courtyard house seems
    to be deficient, and the assumption that the Courtyard is a passive architectural design
    element needs to be substantiated. Therefore, the purpose of this study is to
    investigate the microclimatic performance of a fully enclosed courtyard and noncourtyard
    residential buildings. The main objective is to compare their microclimatic
    performances in other to draw a conclusion on the best option. Three Hobo Weather
    Data Loggers were used to collect climatic data in the buildings, and the third one was
    situated in the outdoor area as a benchmark. The climatic variables investigated are;
    air temperature and relative humidity. The fully enclosed courtyard residential building
    is seen to have a better air temperature difference of 2 oC to 4 oC and the relative
    humidity of 2 % to 6 %. In conclusion, the fully enclosed courtyard residential building
    has confirmed a more favorable microclimatic performance, and future studies
    towards its optimization are recommended.
    Matched MeSH terms: Humidity
  9. Kian Tsong Ho, Mohd Zainal Abidin Ab Kadir, Mahdi Izadi
    MyJurnal
    In this paper, cap and pin porcelain insulator was studied under an environment with different levels
    of humidity. The electric field strength and voltage distribution profile along the insulator string was
    simulated using a computational software package. In this study, ANSYS Maxwell based on the Finite
    Element Method (FEM) was used to simulate the short standard insulator string. The short standard
    insulator string was modelled as a five-unit cap and pin porcelain insulator that was stacked according
    to the IEC 60383 standard. Different humidity levels measured using relative humidity is applied to
    the insulator. From this simulation, the locations within the insulator under high electric field stress are
    identified when different humidity is applied.
    Matched MeSH terms: Humidity
  10. Jawad HM, Nordin R, Gharghan SK, Jawad AM, Ismail M, Abu-AlShaeer MJ
    Sensors (Basel), 2018 Oct 13;18(10).
    PMID: 30322176 DOI: 10.3390/s18103450
    The use of wireless sensor networks (WSNs) in modern precision agriculture to monitor climate conditions and to provide agriculturalists with a considerable amount of useful information is currently being widely considered. However, WSNs exhibit several limitations when deployed in real-world applications. One of the challenges faced by WSNs is prolonging the life of sensor nodes. This challenge is the primary motivation for this work, in which we aim to further minimize the energy consumption of a wireless agriculture system (WAS), which includes air temperature, air humidity, and soil moisture. Two power reduction schemes are proposed to decrease the power consumption of the sensor and router nodes. First, a sleep/wake scheme based on duty cycling is presented. Second, the sleep/wake scheme is merged with redundant data about soil moisture, thereby resulting in a new algorithm called sleep/wake on redundant data (SWORD). SWORD can minimize the power consumption and data communication of the sensor node. A 12 V/5 W solar cell is embedded into the WAS to sustain its operation. Results show that the power consumption of the sensor and router nodes is minimized and power savings are improved by the sleep/wake scheme. The power consumption of the sensor and router nodes is improved by 99.48% relative to that in traditional operation when the SWORD algorithm is applied. In addition, data communication in the SWORD algorithm is minimized by 86.45% relative to that in the sleep/wake scheme. The comparison results indicate that the proposed algorithms outperform power reduction techniques proposed in other studies. The average current consumptions of the sensor nodes in the sleep/wake scheme and the SWORD algorithm are 0.731 mA and 0.1 mA, respectively.
    Matched MeSH terms: Humidity
  11. Ngah Nasaruddin A, Tee BT, Musthafah MT, Md Jasman MES
    Data Brief, 2019 Dec;27:104534.
    PMID: 31709283 DOI: 10.1016/j.dib.2019.104534
    The rapid development of open source developmental boards incorporating microcontrollers on printed circuit boards has offered many alternatives in creating feasible, low cost indoor environment monitoring and controlling platforms. Data are collected and stored in predetermined locations throughout a series of communication activities between a network of active sensors and their processing units. However, the issue of data precision and accuracy are of real concern for generating baseline information. Therefore, with that in mind, the purpose of this paper is to accentuate an insightful trend of retrieving indoor environment data (temperature and relative humidity) for an office building in a hot and humid climate condition. The indoor parameters were monitored using a combination of a single board microcontroller with an active sensor with well calibrated thermal microclimate devices. Accordingly, it was found that proactive adjustment can be conducted in order to minimize waste.
    Matched MeSH terms: Humidity
  12. Rendana M, Idris WMR
    J Infect Public Health, 2021 Oct;14(10):1320-1327.
    PMID: 34175236 DOI: 10.1016/j.jiph.2021.05.019
    BACKGROUND: World Health Organization has reported fifty countries have now detected the new coronavirus (B.1.1.7 variant) since a couple of months ago. In Indonesia, the B.1.1.7 cases have been found in several provinces since January 2021, although they are still in a lower number than the old variant of COVID-19. Therefore, this study aims to create a forecast analysis regarding the occasions of COVID-19 and B.1.1.7 cases based on data from the 1st January to 18th March 2021, and also analyze the association between meteorological factors with B.1.1.7 incidences in three different provinces of Indonesia such as the West Java, South Sumatra and East Kalimantan.

    METHODS: We used the Autoregressive Moving Average Models (ARIMA) to forecast the number of cases in the upcoming 14 days and the Spearman correlation analysis to analyze the relationship between B.1.1.7 cases and meteorological variables such as temperature, humidity, rainfall, sunshine, and wind speed.

    RESULTS: The results of the study showed the fitted ARIMA models forecasted there was an increase in the daily cases in three provinces. The total cases in three provinces would increase by 36% (West Java), 13.5% (South Sumatra), and 30% (East Kalimantan) as compared with actual cases until the end of 14 days later. The temperature, rainfall and sunshine factors were the main contributors for B.1.1.7 cases with each correlation coefficients; r = -0.230; p < 0.05, r = 0.211; p < 0.05 and r = -0.418; p < 0.01, respectively.

    CONCLUSIONS: We recapitulated that this investigation was the first preliminary study to analyze a short-term forecast regarding COVID-19 and B.1.1.7 cases as well as to determine the associated meteorological factors that become primary contributors to the virus spread.

    Matched MeSH terms: Humidity
  13. Tripathy A, Pramanik S, Manna A, Bhuyan S, Azrin Shah NF, Radzi Z, et al.
    Sensors (Basel), 2016 Jul 21;16(7).
    PMID: 27455263 DOI: 10.3390/s16071135
    Despite the many attractive potential uses of ceramic materials as humidity sensors, some unavoidable drawbacks, including toxicity, poor biocompatibility, long response and recovery times, low sensitivity and high hysteresis have stymied the use of these materials in advanced applications. Therefore, in present investigation, we developed a capacitive humidity sensor using lead-free Ca,Mg,Fe,Ti-Oxide (CMFTO)-based electro-ceramics with perovskite structures synthesized by solid-state step-sintering. This technique helps maintain the submicron size porous morphology of the developed lead-free CMFTO electro-ceramics while providing enhanced water physisorption behaviour. In comparison with conventional capacitive humidity sensors, the presented CMFTO-based humidity sensor shows a high sensitivity of up to 3000% compared to other materials, even at lower signal frequency. The best also shows a rapid response (14.5 s) and recovery (34.27 s), and very low hysteresis (3.2%) in a 33%-95% relative humidity range which are much lower values than those of existing conventional sensors. Therefore, CMFTO nano-electro-ceramics appear to be very promising materials for fabricating high-performance capacitive humidity sensors.
    Matched MeSH terms: Humidity
  14. Jathar LD, Ganesan S, Awasarmol U, Nikam K, Shahapurkar K, Soudagar MEM, et al.
    Environ Pollut, 2023 Jun 01;326:121474.
    PMID: 36965686 DOI: 10.1016/j.envpol.2023.121474
    Recently, solar photovoltaic (PV) technology has shown tremendous growth among all renewable energy sectors. The attractiveness of a PV system depends deeply of the module and it is primarily determined by its performance. The quantity of electricity and power generated by a PV cell is contingent upon a number of parameters that can be intrinsic to the PV system itself, external or environmental. Thus, to improve the PV panel performance and lifetime, it is crucial to recognize the main parameters that directly influence the module during its operational lifetime. Among these parameters there are numerous factors that positively impact a PV system including the temperature of the solar panel, humidity, wind speed, amount of light, altitude and barometric pressure. On the other hand, the module can be exposed to simultaneous environmental stresses such as dust accumulation, shading and pollution factors. All these factors can gradually decrease the performance of the PV panel. This review not only provides the factors impacting PV panel's performance but also discusses the degradation and failure parameters that can usually affect the PV technology. The major points include: 1) Total quantity of energy extracted from a photovoltaic module is impacted on a daily, quarterly, seasonal, and yearly scale by the amount of dust formed on the surface of the module. 2) Climatic conditions as high temperatures and relative humidity affect the operation of solar cells by more than 70% and lead to a considerable decrease in solar cells efficiency. 3) The PV module current can be affected by soft shading while the voltage does not vary. In the case of hard shadowing, the performance of the photovoltaic module is determined by whether some or all of the cells of the module are shaded. 4) Compared to more traditional forms of energy production, PV systems offer a significant number of advantages to the environment. Nevertheless, these systems can procure greenhouse gas emissions, especially during the production stages. In conclusion, this study underlines the importance of considering multiple parameters while evaluating the performance of photovoltaic modules. Environmental factors can have a major impact on the performance of a PV system. It is critical to consider these factors, as well as intrinsic and other intermediate factors, to optimize the performance of solar energy systems. In addition, continuous monitoring and maintenance of PV systems is essential to ensure maximum efficiency and performance.
    Matched MeSH terms: Humidity
  15. Farahani H, Wagiran R, Hamidon MN
    Sensors (Basel), 2014 Apr 30;14(5):7881-939.
    PMID: 24784036 DOI: 10.3390/s140507881
    Humidity measurement is one of the most significant issues in various areas of applications such as instrumentation, automated systems, agriculture, climatology and GIS. Numerous sorts of humidity sensors fabricated and developed for industrial and laboratory applications are reviewed and presented in this article. The survey frequently concentrates on the RH sensors based upon their organic and inorganic functional materials, e.g., porous ceramics (semiconductors), polymers, ceramic/polymer and electrolytes, as well as conduction mechanism and fabrication technologies. A significant aim of this review is to provide a distinct categorization pursuant to state of the art humidity sensor types, principles of work, sensing substances, transduction mechanisms, and production technologies. Furthermore, performance characteristics of the different humidity sensors such as electrical and statistical data will be detailed and gives an added value to the report. By comparison of overall prospects of the sensors it was revealed that there are still drawbacks as to efficiency of sensing elements and conduction values. The flexibility offered by thick film and thin film processes either in the preparation of materials or in the choice of shape and size of the sensor structure provides advantages over other technologies. These ceramic sensors show faster response than other types.
    Matched MeSH terms: Humidity*
  16. You KY, Mun HK, You LL, Salleh J, Abbas Z
    Sensors (Basel), 2013;13(3):3652-63.
    PMID: 23493127 DOI: 10.3390/s130303652
    A moisture detection of single rice grains using a slim and small open-ended coaxial probe is presented. The coaxial probe is suitable for the nondestructive measurement of moisture values in the rice grains ranging from from 9.5% to 26%. Empirical polynomial models are developed to predict the gravimetric moisture content of rice based on measured reflection coefficients using a vector network analyzer. The relationship between the reflection coefficient and relative permittivity were also created using a regression method and expressed in a polynomial model, whose model coefficients were obtained by fitting the data from Finite Element-based simulation. Besides, the designed single rice grain sample holder and experimental set-up were shown. The measurement of single rice grains in this study is more precise compared to the measurement in conventional bulk rice grains, as the random air gap present in the bulk rice grains is excluded.
    Matched MeSH terms: Humidity*
  17. Ahmad Z, Zafar Q, Sulaiman K, Akram R, Karimov KS
    Sensors (Basel), 2013;13(3):3615-24.
    PMID: 23493124 DOI: 10.3390/s130303615
    In this paper, we present the effect of varying humidity levels on the electrical parameters and the multi frequency response of the electrical parameters of an organic-inorganic composite (PEPC+NiPc+Cu2O)-based humidity sensor. Silver thin films (thickness ~200 nm) were primarily deposited on plasma cleaned glass substrates by the physical vapor deposition (PVD) technique. A pair of rectangular silver electrodes was formed by patterning silver film through standard optical lithography technique. An active layer of organic-inorganic composite for humidity sensing was later spun coated to cover the separation between the silver electrodes. The electrical characterization of the sensor was performed as a function of relative humidity levels and frequency of the AC input signal. The sensor showed reversible changes in its capacitance with variations in humidity level. The maximum sensitivity ~31.6 pF/%RH at 100 Hz in capacitive mode of operation has been attained. The aim of this study was to increase the sensitivity of the previously reported humidity sensors using PEPC and NiPc, which has been successfully achieved.
    Matched MeSH terms: Humidity*
  18. Ghadiry M, Gholami M, Lai CK, Ahmad H, Chong WY
    PLoS One, 2016;11(4):e0153949.
    PMID: 27101247 DOI: 10.1371/journal.pone.0153949
    Generally, in a waveguide-based humidity sensors, increasing the relative humidity (RH) causes the cladding refractive index (RI) to increase due to cladding water absorption. However, if graphene oxide (GO) is used, a reverse phenomenon is seen due to a gap increase in graphene layers. In this paper, this interesting property is applied in order to fabricate differential humidity sensor using the difference between RI of reduced GO (rGO) and nano-anatase TiO2 in a chip. First, a new approach is proposed to prepare high quality nano-anatase TiO2 in solution form making the fabrication process simple and straightforward. Then, the resulted solutions (TiO2 and GO) are effortlessly drop casted and reduced on SU8 two channels waveguide and extensively examined against several humid conditions. Investigating the sensitivity and performance (response time) of the device, reveals a great linearity in a wide range of RH (35% to 98%) and a variation of more than 30 dB in transmitted optical power with a response time of only ~0.7 sec. The effect of coating concentration and UV treatment are studied on the performance and repeatability of the sensor and the attributed mechanisms explained. In addition, we report that using the current approach, devices with high sensitivity and very low response time of only 0.3 sec can be fabricated. Also, the proposed device was comprehensively compared with other state of the art proposed sensors in the literature and the results were promising. Since high sensitivity ~0.47dB/%RH and high dynamic performances were demonstrated, this sensor is a proper choice for biomedical applications.
    Matched MeSH terms: Humidity*
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links