Displaying publications 1 - 20 of 171 in total

  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. 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
  6. 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
  7. 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
  8. Markus Bulus, Lim, Yaik-Wah, Malsiah Hamid
    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
    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. 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
  12. 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*
  13. 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*
  14. 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*
  15. 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*
  16. Jeevananthan C, Muhamad NA, Jaafar MH, Hod R, Ab Ghani RM, Md Isa Z, et al.
    BMJ Open, 2020 11 04;10(11):e039623.
    PMID: 33148753 DOI: 10.1136/bmjopen-2020-039623
    INTRODUCTION: The current global pandemic of the virus that emerged from Hubei province in China has caused coronavirus disease in 2019 (COVID-19), which has affected a total number of 900 036 people globally, involving 206 countries and resulted in a cumulative of 45 693 deaths worldwide as of 3 April 2020. The mode of transmission is identified through airdrops from patients' body fluids such as during sneezing, coughing and talking. However, the relative importance of environmental effects in the transmission of the virus has not been vastly studied. In addition, the role of temperature and humidity in air-borne transmission of infection is presently still unclear. This study aims to identify the effect of temperature, humidity and air quality in the transmission of SARS-CoV-2.

    METHODS AND ANALYSIS: We will systematically conduct a comprehensive literature search using various databases including PubMed, EMBASE, Scopus, CENTRAL and Google Scholar to identify potential studies. The search will be performed for any eligible articles from the earliest published articles up to latest available studies in 2020. We will include all the observational studies such as cohort case-control and cross-sectional studies that explains or measures the effects of temperature and/or humidity and/or air quality and/or anthropic activities that is associated with SARS-CoV-2. Study selection and reporting will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and Meta-Analysis of Observational Studies in Epidemiology guideline. All data will be extracted using a standardised data extraction form and quality of the studies will be assessed using the Newcastle-Ottawa Scale guideline. Descriptive and meta-analysis will be performed using a random effect model in Review Manager File.

    ETHICS AND DISSEMINATION: No primary data will be collected, and thus no formal ethical approval is required. The results will be disseminated through a peer-reviewed publication and conference presentation.


    Matched MeSH terms: Humidity*
  17. Chong Leong G, Uda H
    PLoS One, 2013;8(11):e78705.
    PMID: 24244344 DOI: 10.1371/journal.pone.0078705
    This paper compares and discusses the wearout reliability and analysis of Gold (Au), Palladium (Pd) coated Cu and Pd-doped Cu wires used in fineline Ball Grid Array (BGA) package. Intermetallic compound (IMC) thickness measurement has been carried out to estimate the coefficient of diffusion (Do) under various aging conditions of different bonding wires. Wire pull and ball bond shear strengths have been analyzed and we found smaller variation in Pd-doped Cu wire compared to Au and Pd-doped Cu wire. Au bonds were identified to have faster IMC formation, compared to slower IMC growth of Cu. The obtained weibull slope, β of three bonding wires are greater than 1.0 and belong to wearout reliability data point. Pd-doped Cu wire exhibits larger time-to-failure and cycles-to-failure in both wearout reliability tests in Highly Accelerated Temperature and Humidity (HAST) and Temperature Cycling (TC) tests. This proves Pd-doped Cu wire has a greater potential and higher reliability margin compared to Au and Pd-coated Cu wires.
    Matched MeSH terms: Humidity
  18. Al-Ta'ii HM, Amin YM, Periasamy V
    Sci Rep, 2016 05 10;6:25519.
    PMID: 27160654 DOI: 10.1038/srep25519
    Deoxyribonucleic acid or DNA based sensors, especially as humidity and alpha particle sensors have become quite popular in recent times due to flexible and highly optimizable nature of this fundamental biomaterial. Application of DNA electronics allow for more sensitive, accurate and effective sensors to be developed and fabricated. In this work, we examined the effect of different humidity conditions on the capacitive and resistive response of Aluminum (Al)/DNA/Al Schottky barrier structure when bombarded by time-dependent dosages of alpha particles. Based on current-voltage profiles, which demonstrated rectifying behaviours, Schottky diode parameters such as ideality factor, barrier height and series resistance was calculated. Results observed generally pointed towards a decrease in the resistance value from the pristine to the radiated structures. It was also demonstrated that under the effect of humidity, the capacitance of the DNA thin film increased from 0.05894 to 92.736 nF, with rising relative humidity level. We also observed the occurrence of the hypersensitivity phenomena after alpha irradiation between 2 to 4 min by observing a drop in the series resistance, crucial in the study of DNA damage and repair mechanisms. These observations may also suggest the exciting possibility of utilizing Al/DNA/Al Schottky diodes as potentially sensitive humidity sensors.
    Matched MeSH terms: Humidity
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