1,720,964 research outputs found
Prediction model of hand arm vibration exposure among hand-held grass-cutters in Malaysia
Full text linkProlonged exposures to hand-transmitted vibrations from grass-cutting machines have been associated with increasing occurrences of signs of occupational diseases related to the hand-arm vibration syndrome (HA VS). However, there are no specific processes available that cover the objective and subjective health cause-effects of the hand arm vibration risk factors during onsite operations. Most of the existing vibration control measures have not extensively integrated administration and engineering techniques to be utilized as health prediction screening models. Therefore, the main objectives of this study are to integrate the engineering and administration control approach for reducing HA VS among hand-held grass-cutting workers and to determine the significant correlation of the objective and subjective measurement variables of the Hand Arm Vibration Exposure Risk Assessment (HAVERA) on hand arm vibration symptoms and disorders. The study was conducted in two stages: evaluation of the HA VERA variables (Stage 1) and development of the health prediction cause-effect model of the HA VERA process using multiple linear regressions and feed forward neural network programming (Stage 2). For the onsite measurement, the daily vibration value depicted an exceeded exposure action value of 2.5 m/s2 for both hands; and experiences of any finger colour change were claimed by 80% of the 204 subjects. This shows that the HA VERA process provided a good indication of HA VS which are reported as vascular, neurological and musculoskeletal disorders. In the right and left hand prediction model development, the results of the neural network model demonstrated a higher reliability performance as compared to the linear model for hand grip strength and hand numerical scoring assessment. The prediction of the HA VERA model using the neural network method has been developed for monitoring health conditions due to hand-transmitted vibrations among hand-held grass-cutting workers in Malaysi
Octave band technique for noise measurement at the source, path, and receiver of gas turbines in oil and gas facilities
No full textNoise measurement is essential for industrial usage. However, further attention to preventing
noise pollution is needed, especially when working with equipment generating a high noise
level, such as gas turbines. This study aims to determine the best way to perform noise
measurement and analyze the octave band frequency generated by noise pollution caused
by gas turbine equipment. Data from site measurements show that the gas turbines produce
more than 85 dB of noise with a Z-weighted measurement. A noise measuring investigation
was conducted to obtain the data for the 1/3 octave band. A frequency-domain was used to
comprehend the properties of the noise measurement frequency band. The frequency band
was classified into three different zones called low, medium, and high frequency, which is
useful in noise measurement analysis to identify a viable solution to reduce the noise. On�site sampling was performed at the source, path, and receiver of three separate gas turbine
locations within oil and gas operations. The 1/3 octave band data collection results at the
sound source, path, and receiver demonstrate the noise level distribution at the perimeter
of gas turbine installations in the low and medium frequency ranges. Most of the high
noise frequency range is between 250 Hz and 2 kHz for source, path, and receiver. All
acquired values are compared to the Department of Safety and Health (Occupational Safety
and Health (Noise Exposure) Regulations
2019 in Malaysia. As a result, oil and gas
service operators can monitor and take
countermeasures to limit noise exposure at
oil and gas facilities
Flow Channeling And Restriction Zone Identification in Gas Mask Filter Cartridges using CFD
Full text linkGas mask filters are critical for protecting against hazardous gases and airborne pollutants, yet their performance is strongly influenced by internal airflow behavior. In this study, Computational Fluid Dynamics (CFD) was employed to investigate pressure drop, velocity distribution, and air age (residence time) within a gas mask cartridge. The simulations revealed a maximum pressure drop of 41.94 Pa, well within acceptable breathing resistance limits, but with non-uniform distribution across the absorbent bed. Velocity contours showed flow channeling forming near the inlet and outlet, leaving regions further from the outlet underutilized. Air age analysis confirmed these patterns, with some regions achieving the required 0.67–0.80 s contact time for effective adsorption, while others fell below this threshold. Under humid conditions, resistance increased, leading to longer residence times but reduced overall airflow renewal. These findings highlight that both cartridge can affect airflow uniformity, adsorption efficiency, and sorbent utilization. The findings can guide the optimization of filter design in achieve more balanced flow distribution and improved performance.
 
Flow Channeling And Restriction Zone Identification in Gas Mask Filter Cartridges using CFD
Full text linkGas mask filters are critical for protecting against hazardous gases and airborne pollutants, yet their performance is strongly influenced by internal airflow behavior. In this study, Computational Fluid Dynamics (CFD) was employed to investigate pressure drop, velocity distribution, and air age (residence time) within a gas mask cartridge. The simulations revealed a maximum pressure drop of 41.94 Pa, well within acceptable breathing resistance limits, but with non-uniform distribution across the absorbent bed. Velocity contours showed flow channeling forming near the inlet and outlet, leaving regions further from the outlet underutilized. Air age analysis confirmed these patterns, with some regions achieving the required 0.67–0.80 s contact time for effective adsorption, while others fell below this threshold. Under humid conditions, resistance increased, leading to longer residence times but reduced overall airflow renewal. These findings highlight that both cartridge can affect airflow uniformity, adsorption efficiency, and sorbent utilization. The findings can guide the optimization of filter design in achieve more balanced flow distribution and improved performance.
 
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Predicting indoor air quality (IAQ) on naval ship: a contour mapping approach to air distribution
No full textAbstract: Ships often report poor indoor air quality (IAQ) due to their enclosed and confined spaces. The main factor contributing to poor IAQ onboard was the inefficiency of the heating, ventilation, and air conditioning (HVAC) systems. Poor IAQ adversely affects the health of the crew, which can indirectly cause Sick Boat syndrome (SBoS). Therefore, close monitoring of HVAC efficiency and IAQ on naval ships is crucial, as these vessels serve as the operational homes for our nation's front liners. This paper aims to analyse air distribution from the HVAC system by simulating the temperature, carbon dioxide (CO₂), and particulate matter (PM2.5) within the designated ship’s compartment. Using NoiseAtWork software, a contour mapping method was employed to visualise the spatial distribution of selected IAQ parameters. Before that, real-time sampling of selected IAQ parameters was done on the bridge. The contour map of the air distribution revealed that open hatches affected the dispersion of CO₂ and PM2.5, leading to variations in concentration contours within the area. PM2.5 map showed PM2.5 accumulation, possibly due to old dust from the ducting and diffusers. Although temperature distribution was even, it did not comply with ICOP IAQ 2010 standards. This study underscores the importance of air distribution prediction, thus highlighting the necessity for crew adherence to the best practices, such as closing the hatch, and perform maintenance including ducting cleaning as recommended by the design systems or the class society to maintain healthy indoor environments. Therefore, by using NoiseAtWork, the contour mapping method can help to predict the influence of HVAC efficiency and operational practices on IAQ. This method is valuable for identifying the optimal HVAC component configurations such as the best location of an air diffuser for the new shipbuilding project. Ensuring proper air circulation throughout the ship will enhance HVAC system efficiency and improve the IAQ onboard
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Prediction on hand arm vibration exposure cause-effect among grass-cutting workers in Malaysia
No full textProlonged exposures to hand-transmitted vibrations from grass-cutting machines have been associated with increasing occurrences of signs of occupational diseases related to the hand-arm vibration syndrome (HAVS). However, there are no specific processes available that cover the subjective and objective health cause-effects of the hand arm vibration risk factors during onsite operations. The objectives are (1) to measure the health subjective and objective risks during normal working conditions among hand-held grass-cutting workers and (2) to determine the significant correlation of the subjective and objective measurement variables of the Hand Arm Vibration Exposure Risk Assessment (HAVERA) on hand arm vibration symptoms and disorders. The study was conducted in two stages: evaluation of the HAVERA variables and development of the health prediction cause-effect model of the HAVERA process using multiple linear regressions and feed forward neural network programming. In the onsite measurement, the daily vibration value depicted an exceeded exposure action value of 2.5 m/s2 for both hands; and experiences of any finger colour change were claimed by 80% of the 204 subjects. This shows that HAVERA process provided a good indication of HAVS which are reported as vascular, neurological and musculoskeletal disorders. In the right and left hand prediction model development, the results demonstrated a higher reliability performance as compared to the linear model for hand grip strength and hand numerical scoring assessment. The prediction of the HAVERA model using the neural network method has been developed for monitoring health conditions due to hand-transmitted vibrations among hand-held grasscutting workers in Malaysia
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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