Flow of a low concentration polyacrylamide fluid solution in a channel with a flat plate obstruction at the entry

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.

Analysis of spray uniformity and distribution by boom height and operating pressure under test bench and field condition

( 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.

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 evaluation of two calibration procedures using thermal desorption-gas chromatography in the analysis of odorous volatile compounds.

Kabir, Ehsanul,Kim, Ki-Hyun Preston Publications 2011 Journal of Chromatographic Science Vol.49 No.9

<P>In this study, the relative performance of gas chromatography (GC) was investigated with respect to the differences in two types of calibration approaches with a thermal desorption (TD) method: the fixed standard concentration approach (FSC: the comparison of different sample volumes for a given standard) was compared with the fixed standard volume approach (FSV: the comparison of different concentration standards at a fixed loading volume). Gaseous working standards of seven odorants, including methyl ethyl ketone (MEK), butyl acetate, methyl isobutyl ketone, isobutyl alcohol, toluene, xylene, and a reference component, benzene, were prepared at four concentration levels (10-100 ppb). They were then analyzed by controlling the TD-loading volumes at six levels (40-1200 mL). The results derived by these contrasting calibration approaches showed moderate changes in the GC sensitivity, either with an increasing concentration (i.e., FSC), or with an increasing sample loading volume (i.e., FSV). Despite an eccentric trend of MEK, the TD-based analysis was fairly predictable and can be recommended for the analysis of the selected odorants.</P>

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.

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.

A Formula Derivation of Channel Capacity Calculation in a MIMO System

Kabir, S.M.Humayun,Lee, Eun-Ju,Yoon, Gi-Wan The Korea Institute of Information and Commucation 2009 Journal of information and communication convergen Vol.7 No.2

In this letter, we derive a tight closed-form formula for an ergodic capacity of a multiple-input multiple-output (MIMO) for the application of wireless communications. The derived expression is a simple closed-form formula to determine the ergodic capacity of MIMO systems. Assuming the channels are independent and identically distributed (i.i.d.) Rayleigh flat-fading between antenna pairs, the ergodic capacity can be expressed in a closed form as the finite sum of exponential integrals.

Trace metal contents in barbeque (BBQ) charcoal products

Kabir, Ehsanul,Kim, Ki-Hyun,Yoon, H.O. Elsevier 2011 Journal of hazardous materials Vol.185 No.2

<P><B>Abstract</B></P><P>In this study, the concentrations of trace elements contained in solid barbeque (BBQ) charcoal products have been investigated. Eleven brands of charcoal products were analyzed, consisting of both Korean (3 types) and imported products (eight types from three countries) commonly available in the Korean market places. The concentrations of trace metals in solid charcoal varied widely across metal types and between samples with the overall range of 5μgkg<SUP>−1</SUP> (As) to 118mgkg<SUP>−1</SUP> (Zn). The patterns of metal distribution between different products appeared to be affected by the properties of raw materials and/or the processes involved in their production. Although concentrations of certain trace metals were significantly high in certain charcoal samples, their emission concentrations were below legislative guidelines (e.g., the permissible exposure limit (PEL) set by the Occupational Safety and Health Administration (OSHA)). In light of the potential harm of grilling activities, proper regulation should be considered to control the use of BBQ charcoal from a toxicological viewpoint to help reduce the potential health risks associated with its use.</P>

An investigation on hazardous and odorous pollutant emission during cooking activities

Kabir, E.,Kim, K.H. Elsevier Scientific Pub. Co 2011 Journal of hazardous materials Vol.188 No.1

In this study, the emission characteristics of various pollutants (e.g., reduced sulfur compounds (RSCs), aldehydes, volatile organic compounds (VOCs), and organic acids) were investigated in relation to 3 food types (including cabbage, clam, and coffee seeds) and 2 cooking methods (between mild and harsh treatments). The results indicated the strongest emissions from the roasted coffee seeds out of all 6 sample types. Among the pollutant types, the maximum emissions generally came from RSCs followed by aldehydes and acids. Among VOCs, toluene and methyl ethyl ketone were emitted most prominently. As most of these pollutants also represent key odorants, their concentrations are compared through a conversion into odor intensity (OI); the results showed the RSC group as the key odorants along with aldehydes and organic acid compounds. If the sum of odor intensity (SOI) is derived for each sample, they were in the descending order: roasting coffee seeds (6.50), frying cabbage (4.52), brewing coffee (4.14), grilling clam (3.91), boiling clam (3.89), and steaming cabbage (3.21). Their concentration data were also evaluated against regulation guidelines for indoor air quality (IAQ). Comparison of these pollutant data confirms that some cooking approaches can contribute significantly to the build up of nuisance and hazardous pollution concurrently.

Reader level filtering for efficient query processing in RFID middleware

Kabir, Muhammad Ashad,Han, Jun,Hong, Bonghee Elsevier 2015 JOURNAL OF NETWORK AND COMPUTER APPLICATIONS - Vol.48 No.-

<P><B>Abstract</B></P> <P>In RFID systems, middleware is used to filter a large amount of streaming data gathered continuously from readers to process application requests. The high volume of data makes the middleware often in a highly overloaded situation. The reader filtering capability can be used to reduce data volume and middleware work-load. However, if the middleware dispatches query conditions to readers without any adjustment, it may generate a huge amount of duplicate data and imposes considerable load on the middleware. As such, an appropriate schema for data volume reduction is required. In this paper, we propose a query decomposition technique to divide queries into sub-queries for middleware and reader level execution. This new approach of query execution resolves the problem of duplicate data generation. Our experiments show that the proposed approach considerably improves the performance of middleware by reducing query processing time and network traffic between reader and middleware.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We exploit RFID readers' filtering capability for processing query efficiently. </LI> <LI> We present query models for RFID middleware and reader. </LI> <LI> We present algorithms to decompose query to process by middleware and reader. </LI> <LI> Our approach resolves the problem of duplicate data generation and improves the performance of middleware. </LI> </UL> </P>