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Kabir, M.A.,Khan, M.M.K.,Rasul, M.G. The Korean Society of Rheology 2004 Korea-Australia rheology journal Vol.16 No.2
Flow in a channel with an obstruction at the entry can be reverse, stagnant or forward depending on the position of the obstruction. These flow phenomena have potential applications in the control of energy and various flows in process engineering. Parameters that affect this flow inside and around the test channel are the gap (g) between the obstruction geometry and the test channel, the Reynolds number (Re) and the length (L) of the test channel. The influence of these parameters on the flow behavior was investigated using a flat plate obstruction at the entry of the channel. A low concentration polyacrylamide solution (0.018% by weight) showing a powerlaw fluid behavior was used as the fluid in this investigation. The flow phenomena were investigated by the velocity measurement and the flow visualization and their results were compared with numerical simulation. These results of low concentration polyacrylamide solution are also compared with the results of water published elsewhere (Kabir et al., 2003). The maximum reverse flow inside the test channel observed was 20% - 30% of the outside test channel velocity at a g/w (gap to width) ratio of 1 for Reynolds numbers of 1000 to 3500. The influence of the test channel length (L) and the Reynolds number (Re) on the velocity ratio ($V_i$/$V_o$: inside velocity/outside velocity in the test channel) are also presented and discussed here.
( Sazzadul Kabir ),( Ashrafuzzamn Gulandaz ),( Nasim Reza ),( Mohammod Ali ),( Shaha Nur Kabir ),( Sun-ok Chung ) 한국농업기계학회 2023 한국농업기계학회 학술발표논문집 Vol.28 No.1
Excessive use of pesticide increase production costs and negatively impact on the environment. Increasing spraying effectiveness is one of the major goals of precision variable rate technologies. The technical performance of the nozzle significantly impacts sprayer performance and quality. Analysis of the effects of operating pressure and boom height on spray dispersal and uniformity was the goal of this research. The test bench consisted of four nozzles (NN D-35) and a single-cylinder motor with a four-stroke capacity of 0.72 kW. This self-propelled sprayer was tasted on the ground with 2 km/h speed. Experiments were conducted both in lab and field condition with conventional spray nozzles and water as the test liquid. Tested liquid outflow pressure ranged from 280 to 520 kPa. Depending on the spraying target surface, 35, 45, and 55 cm of working spray boom height were adjusted. The nozzle spacing was 30 cm and the spray angle of the nozzles was 110o. Resultant sprayer nozzle widths with boom heights of 35, 45, and 55 cm caused overlaps of 22.38%, 23.43%, and 24.15% under the lab condition and 24.11%, 26.32%, and 29.37% under field condition. Under the laboratory condition average droplet density levels of 155.38, 159.20, and 168.31 (spots/cm2) were achieved at boom heights of 35, 45, and 55 cm with a speed of 2 km/h, resulting in the spray coverage levels of 23.21%, 26.38%, and 28.35%, respectively. At boom heights of 35, 45, and 55 cm at a speed of 2 km/h, average droplet densities of 138.62, 151.22, and 171.91 (spots/cm2) were obtained under the field yielding spray coverage levels of 24.11%, 26.38%, and 29.37%, correspondingly. Under the both conditions, the 55 cm boom overlapped less than 30%, and the average droplet density and spray coverage in unit area were better than the other two boom heights. It would also be economical and environmentally friendly to use these spraying tools.
Chemical Characteristics of Groundwater in Carbonate Rock Areas of Korea
Kabir, Mohammad Lutful,Park, Youngyun,Lee, Jin-Yong Korean Society of Soil and Groundwater Environment 2014 지하수토양환경 Vol.19 No.2
This study was conducted to understand the chemical characteristics of groundwater in carbonate areas of Korea. In this study, data on pH, electric conductivity (EC), $Ca^{2+}$, $Mg^{2+}$, $Na^+$, $K^+$, $Cl^-$, $SO_4{^{2-}}$, and $HCO_3{^-}$ were collected from 97 wells which were installed in various carbonate rock regions of Korea. The pH values ranged from 5.7 to 9.9, and the average value was 7.3. The concentration range showed differences between the maximum value of $HCO_3{^-}$ and the medium to minimum values of $Ca^{2+}$, $Mg^{2+}$, $Na^+$, $Cl^-$, $SO_4{^{2-}}$, and $K^+$ in the study area. The average value of EC was $374{\mu}S/cm$, higher than in granite and gneiss areas, where the value is $176{\mu}S/cm$. Most of the groundwater was type $Ca-HCO_3$, and some was type $Mg-HCO_3$. The relationship between $Ca^{2+}$, $Cl^-$, and $HCO_3{^-}$, respectively, and EC showed relatively significant positive correlations compared to the other dissolved components. However, the determination coefficients for $Mg^{2+}$, $Na^+$, $SO_4{^{2-}}$, and $K^+$ were very low less than 0.2. These results indicate that the source of $Ca^{2+}$ and $Mg^{2+}$ is relatively simple (carbonate dissolution) compared to other sources. The sources of $Na^+$, $K^+$, $Cl^-$, $SO_4{^{2-}}$, and $HCO_3{^-}$ might be not only water-rock interactions, but also irrigation return flow, because many groundwater wells had been developed for irrigation purposes. Subsequently, the influence of agriculture on groundwater chemistry was evaluated using a cumulative plot of $SO_4{^{2-}}$. The threshold value of $SO_4{^{2-}}$ calculated from the cumulative frequency curve was 29.2 mg/L. Therefore, 12.4% of all the groundwater wells were affected by agricultural activity.
Yield monitoring systems for non-grain crops: A review
KABIR MD SAZZADUL,GULANDAZ MD ASHRAFUZZAMAN,ALI MOHAMMOD,레자 나심,사하눌 카빌,정선옥,한광민 충남대학교 농업과학연구소 2024 Korean Journal of Agricultural Science Vol.51 No.1
Yield monitoring systems have become integral to precision agriculture, providing insights into the spatial variability of crop yield and playing an important role in modern harvesting technology. This paper aims to review current research trends in yield monitoring systems, specifically designed for non-grain crops, including cabbages, radishes, potatoes, and tomatoes. A systematic literature survey was conducted to evaluate the performance of various monitoring methods for non-grain crop yields. This study also assesses both mass- and volume-based yield monitoring systems to provide precise evaluations of agricultural productivity. Integrating load cell technology enables precise mass flow rate measurements and cumulative weighing, offering an accurate representation of crop yields, and the incorporation of image-based analysis enhances the overall system accuracy by facilitating volumetric flow rate calculations and refined volume estimations. Mass flow methods, including weighing, force impact, and radiometric approaches, have demonstrated impressive results, with some measurement error levels below 5%. Volume flow methods, including paddle wheel and optical methodologies, yielded error levels below 3%. Signal processing and correction measures also play a crucial role in achieving accurate yield estimations. Moreover, the selection of sensing approach, sensor layout, and mounting significantly influence the performance of monitoring systems for specific crops.
Feasibility of Streaming Potential Signal on Estimation of Solute Transport Characteristics
Kabir, Mohammad Lutful,Ji, Sung- Hoon,Lee, Jin-Yong,Koh, Yong- Kwon Korean Society of Soil and Groundwater Environment 2015 지하수토양환경 Vol.20 No.2
The drag of the excess charge in an electrical double layer at the solid fluid interface due to water flow induces the streaming current, i.e., the streaming potential (SP). Here we introduce a sandbox experiment to study this hydroelectric coupling in case of a tracer test. An acrylic tank was filled up with homogeneous sand as a sand aquifer, and the upstream and downstream reservoirs were connected to the sand aquifer to control the hydraulic gradient. Under a steady-state water flow condition, a tracer test was performed in the sandbox with the help of peristaltic pump, and tracer samples were collected from the same interval of five screened wells in the sandbox. During the tracer test, SP signals resulting from the distribution of 20 nonpolarizable electrodes were measured at the top of the tank by a multichannel meter. The results showed that there were changes in the observed SP after injection of tracer, which indicated that the SP was likely to be related to the solute transport.
An Efficient Approach for Lightpath Restoration in WDM Networks
Kabir, S.M. Humayun,Pham, Van Su,Yoon, Gi-Wan The Korea Institute of Information and Commucation 2008 Journal of information and communication convergen Vol.6 No.1
WDM is an incredibly promising technique in which multiple channels are operated along a single fiber, providing the facilities of terabit per second bandwidth. Thus, the survivability of WDM networks becomes critical for the success of the next generation internet architecture. Despite the fact that the path-based proactive restoration scheme guarantees 100% restoration as it computes a backup light path while the primary light path is being set up, this method results in additional capacity consumption. In this paper, an ideal technique is proposed that modifies the active multi-backup paths method and results in a better restoration scheme. Based on a theoretical analysis, a new method is shown to reduce the number of hopes as well as the restoration time.
Behavior modeling and damage quantification of confined concrete under cyclic loading
Kabir Sadeghi,Fatemeh Nouban 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.5
Sets of nonlinear formulations together with an energy-based damage index (DI) are proposed to model the behavior and quantify the damage of the confined and unconfined concretes under monotonic and cyclic loading. The proposed formulations and DI can be employed in numerical simulations to determine the stresses and the damages to the fibers or the layers within the sections of reinforced concrete (RC) components. To verify the proposed formulations, an adaptive finite element computer program was generated to simulate the RC structures subjected to monotonic and cyclic loading. By comparing the simulated and the experimental test results, on both the full-scale structural members and concrete cylindrical samples, the proposed uniaxial behavior modeling formulations for confined and unconfined concretes under monotonic and cyclic loading, based on an iterative process, were accordingly adjusted, and then validated. The proposed formulations have strong mathematical structures and can readily be adapted to achieve a higher degree of precision by improving the relevant coefficients based on more precise tests. To apply the proposed DI, the stress-strain data of concrete elements is required. It can easily be calculated by using the proposed nonlinear constitutive laws for confined and unconfined concretes in this paper.