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Tytuł:
A cross sectional survey on health and nutritional status among the people of Chittagong city corporation, Bangladesh
Autorzy:
Jakaria, M.
Hasan, M.
Hossain, M.S.
Hasanat, A.
Sayeed, M.A.
Powiązania:
https://bibliotekanauki.pl/articles/1917281.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Medyczny w Białymstoku
Tematy:
Health
Chittagong city
nutritional status
survey
Respondents
Opis:
Purpose: To determine the health and nutritional status of people in the Chittagong city corporation area of Bangladesh. Materials and methods: A face-to-face interview methodology was used for this survey. The study sites were located in 15 thanas of the Chittagong city corporation area. The study was also designed with interview questions closely related to health.Results: Among the total 620 respondents, 453 respondents were males and 167 respondents were females. 471(75.96%) of the total respondents had positive comments about the health status of their community. 169(27.52%) respondents had poor or fair appetites but the rest of them had good, very good or excellent appetites. 360(58.07%) of the respondents reported they had been eating a minimum of one fruit per day and 85(13.7%) people drank 5 to 8 glasses of water daily. 441(71.12%) of their diets more or less met daily vitamin and nutrient requirements and 338(54.51%) were nonsmokers. 407(65.64%) were married, and 388 (62.58%) were more or less satisfied about their sexual life. 441(71.12%) respondents performed physical exercise more or less habitually. A lower number of respondents had a major disease. For instance, 155(25%) suffered from high blood pressure, and 150(24.19%) suffered from diabetes. In the case of minor diseases, 399(64.35%) of the respondents had been suffering from GIT disease and 416(67.09%) were taking proton pump inhibitors or a H2 receptor blockers. 205(33.06%) respondents were taking antibiotics regularly.Conclusions: One third of the people had hypertension and diabetes. According to the biomedical concepts, peoples were not healthy. However, according to the ecological and psychological concepts of health, this survey proved that the people of the Chittagong city corporation area were comparatively healthy.
Źródło:
Progress in Health Sciences; 2015, 5, 1; 114-119
2083-1617
Pojawia się w:
Progress in Health Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Novel Software-Defined Networking Controller : the Distributed Active Information Model (DAIM)
Autorzy:
Pupatwibul, P.
Banjar, A.
Hossain, M. I.
Braun, R.
Moulton, B.
Powiązania:
https://bibliotekanauki.pl/articles/226996.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
distributed network
OpenFlow
DAIM model
software defined networking
next generation networks
Opis:
This paper presents a new OpenFlow controller: the Distributed Active Information Model (DAIM). The DAIM controller was developed to explore the viability of a logically distributed control plane. It is implemented in a distributed way throughout a software-defined network, at the level of the switches. The method enables local process flows, by way of local packet switching, to be controlled by the distributed DAIM controller (as opposed to a centralised OpenFlow controller). The DAIM ecosystem is discussed with some sample code, together with flowcharts of the implemented algorithms. We present implementation details, a testing methodology, and an experimental evaluation. A performance analysis was conducted using the Cbench open benchmarking tool. Comparisons were drawn with respect to throughput and latency. It is concluded that the DAIM controller can handle a high throughput, while keeping the latency relatively low. We believe the results to date are potentially very interesting, especially in light of the fact that a key feature of the DAIM controller is that it is designed to enable the future development of autonomous local flow process and management strategies.
Źródło:
International Journal of Electronics and Telecommunications; 2018, 64, 2; 209-216
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Allometric scaling of marbofloxacin pharmacokinetics: a retrospective analysis
Autorzy:
Yohannes, S.
Hossain, M.A.
Kim, J.Y.
Lee, S.J.
Kwak, D.M.
Suh, J.W.
Park, S.C.
Powiązania:
https://bibliotekanauki.pl/articles/31939.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
The association between physiologically dependent pharmacokinetic parameters (CLB, T1/2β, Vdss) of marbofloxacin and body weight was studied in eight animal species based on allometric equation Y = aWb, where ‘Y’ is the pharmacokinetic parameter, ‘W’ is body weight, ‘a’ is allometric coefficient (intercept) and ‘b’ is the exponent that describes relation between pharmacokinetic parameter and body weight. The body clearance of marbofloxacin has shown significant (P<0.0001) relation with size (Bwt) in various animal species. However, half-life and volume of distribution were not in association with body weight. Although half-life and volume of distribution were not in a good correlation with body weight, statistically significant association between the body clearance and body weight suggests validity of allometric scaling for predicting pharmacokinetic parameters of marbofloxacin in animal species that have not been studied yet. However further study considering large sample size and other parameters influencing pharmacokinetics of marbofloxacin is recommended.
Źródło:
Polish Journal of Veterinary Sciences; 2014, 17, 1
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An effective medium ratio obeying meta-atom for multiband applications
Autorzy:
Hossain, M. J.
Faruque, M. R. I.
Islam, M. T.
Islam, S. S.
Powiązania:
https://bibliotekanauki.pl/articles/201192.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
compact
effective medium ratio
meta-atom
multiband
kompakt
średni wskaźnik efektywności
Opis:
In this paper, an effective medium ratio obeying, negative refractive index, compact meta-atom was designed, manufactured and tested for operation in a multiband microwave regime. The proposed meta-atom structure obeyed better effective medium ratio. The results of the measurement were verified by the commercially available Computer Simulation Technology (CST) Studio Suite 2014 simulator. The effective medium ratio obeying meta-atom displayed multiband response, in conjunction with negative refractive index property over a certain frequency band in the microwave frequency span. Furthermore, a few parametric analyses were completed with the meta-atom, and the effective medium parameters were investigated. The sizes and complex scattering constitutive parameters of the proposed negative refractive index, compact meta-atom are applicable for multiband applications in microwave regime.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2017, 65, 2; 139-147
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conjugate heat and mass transfer on fluctuating mixed convection flow along a vertical wedge with thermal radiation
Autorzy:
Firoza, M. N.
Roy, N. C.
Hossain, A.
Powiązania:
https://bibliotekanauki.pl/articles/264573.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
mixed convection
thermal radiation
vertical wedge
promieniowanie cieplne
przepływ ciepła
niska częstotliwość
Opis:
We study the boundary layer characteristics of heat and mass transfer flow past a vertical wedge in the presence of thermal radiation. The surface temperature and the species concentration are assumed to be oscillating in the magnitude but not in the direction of oncoming flow velocity. The governing equations have been solved by two distinct methods, namely, the straightforward finite difference method for the entire frequency range, and the series solution for the low frequency range and the asymptotic series expansion method for the high frequency range. Numerical solutions have been presented in terms of the amplitudes and phase angles of the skin friction, the rate of heat transfer and the mass transfer with the variations of Richardson’s number, the Prandtl number, the conduction–radiation parameter, the surface temperature parameter and the Schmidt number. Furthermore, the effects of these parameters are examined in terms of the transient skin friction, heat transfer and mass transfer.
Źródło:
International Journal of Applied Mechanics and Engineering; 2017, 22, 3; 539-565
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diurnal seismic ambient noise and seismic station performance characterization in the Bengal Basin, Bangladesh
Autorzy:
Zannat, Naharin
Farazi, Atikul Haque
Kamal, A. S. M. Maksud
Rahman, Md. Zillur
Hossain, Md. Shakhawat
Powiązania:
https://bibliotekanauki.pl/articles/27310143.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
seismic ambient noise
power spectral density
noise energy
noise sources
seismic station
Bengal Basin
Opis:
Seismic ambient noise (SAN) energy can potentially blur regional and teleseismic arrivals as well as various microearthquakes at specific frequencies. Therefore, quantification of the SAN energy level in a region is required to optimize seismic station distribution for seismological investigations. Moreover, evaluation of station performance and noise source is possible from observation of SAN energy levels. The SAN energy distribution from seismic stations in the Bengal Basin (BB), Bangladesh has not yet been estimated. At the same time, this tec-tonically active and complex region is less studied using seismic methods. This study aims to quantify SAN ener-gy and characterize its diurnal variation along with evaluating station performance at 11 seismic stations, which were temporarily installed in the deeper portion of the BB. Herein, the daily SAN energy level was determined within the period range of 0.02–30 s by estimating the power spectral density (PSD) of seismic data for 7 continu-ous days. SAN energy and its variation over time were observed using the probability density functions (PDFs) of PSDs and spectrograms, respectively. The sources of SAN energies at different period bands were also investigat-ed by comparing the PSDs with daily variations in human activities, nearby noise sources, local meteorological factors (i.e., air temperature and precipitation), and sea level height. The insights from this study could be useful for the future deployment of seismic networks as well as seismological studies in the BB.
Źródło:
Geology, Geophysics and Environment; 2023, 49, 3; 209--224
2299-8004
2353-0790
Pojawia się w:
Geology, Geophysics and Environment
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic modeling of the isoamyl acetate reactive distillation process
Autorzy:
Ali, S. S.
Hossain, SK. S.
Asif, M.
Powiązania:
https://bibliotekanauki.pl/articles/778351.pdf
Data publikacji:
2017
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
reactive distillation
process simulator
isoamyl acetate
dynamic modeling
disturbance
Opis:
The cost-effectiveness of reactive distillation (RD) processes makes them highly attractive for industrial applications. However, their preliminary design and subsequent scale-up and operation are challenging. Specifically, the response of RD system during fluctuations in process parameters is of paramount importance to ensure the stability of the whole process. As a result of carrying out simulations using Aspen Plus, it is shown that the RD process for isoamyl acetate production was much more economical than conventional reactor distillation configuration under optimized process conditions due to lower utilities consumption, higher conversion and smaller sizes of condenser and reboiler. Rigorous dynamic modeling of RD system was performed to evaluate its sensitivity to disturbances in critical process parameters; the product flow was quite sensitive to disturbances. Even more sensitive was product composition when the disturbance in heat duties of condenser or reboiler led to a temperature decrease. However, positive disturbance in alcohol feed is of particular concern, which clearly made the system unstable.
Źródło:
Polish Journal of Chemical Technology; 2017, 19, 1; 59-66
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of climate change on rice production at Khulna District, Bangladesh
Autorzy:
Hossain, N.
Saifullah, A.S.M.
Bhuiyan, S.H.
Uddin, N.
Rahman, M.
Powiązania:
https://bibliotekanauki.pl/articles/2049750.pdf
Data publikacji:
2019
Wydawca:
Fundacja na Rzecz Młodych Naukowców
Tematy:
rice
production
climate change
trend analysis
Bangladesh
gross domestic product
Mann-Kendall (MK) test
Rice Production
Opis:
In Bangladesh 164 million people depend on rice but due to climate change (CC) vulnerabilities the yield of rice is severely reducing. Therefore, this study aimed to explore the effects of CC on rice yield using recent trend analysis, Mann-Kendall (MK) trend test and correlation. For this study, the required climate and selected rice production data were collected from Bangladesh Meteorological Department (BMD) and Department of Agriculture Extension (DAE), Khulna. In time series statistics both parametric and nonparametric methods were applied to detect a monotonic trend of climatic variability and Aman rice production. Correlation between climatic variability and rice production was also investigated. The study exposed that the temperature and rainfall had an increasing trend and statistically significant whereas the relative humidity found decreasing. Overall, the bright Sunshine had positive trend but week. According to nonparametric trend test of climatic variability and Aman yield only minimum temperature showed a positive trend which found statistically significant. In contrast, Mann-Kendall trend test revealed that rainfall had positively significant while temperature had negative significant. The correlation revealed the Aman production is a strong response with minimum temperature whereas the Lona Coche showed a positive correlation with maximum temperature. The variation of Aman production exhibited a positive correlation with both Rainfall and humidity respectively and Lona Coche found a negative correlation. The sunshine had a week correlation against both yields. The findings suggest should give attention of temperature-tolerant rice varieties to mitigate possible adverse effects of CC.
Źródło:
Environment, Earth and Ecology; 2019, 3, 1; 42-54
2543-9774
2451-4225
Pojawia się w:
Environment, Earth and Ecology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Foliar application of salicylic acid improves growth and yield attributes by upregulating the antioxidant defense system in Brassica campestris plants grown in lead-amended soils
Dolistna aplikacja kwasu salicylowego wpływa korzystnie na parametry wzrostu i plonowania roślin Brassica campestris rosnących w glebie zanieczyszczonej ołowiem poprzez pozytywną regulację systemu obrony antyoksydacyjne
Autorzy:
Hasanuzzaman, M.
Matin, Md.A.
Fardus, J.
Hasanuzzaman, Md.
Hossain, Md.S.
Parvin, K.
Powiązania:
https://bibliotekanauki.pl/articles/28053.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Botaniczne
Opis:
Lead (Pb) toxicity causes a severe impact on plant growth and productivity. A protective role of salicylic acid (SA) is well known under different abiotic stress conditions. However, very little is known about the SA-induced Pb resistance mechanism. In this study, we investigated the effect of SA on mustard plants (Brassica campestris L.) under Pb-stress conditions. Plants were exposed to three levels of Pb amendment to the soil (0.25, 0.50, 1.00 mM), with or without SA (0.25 mM). Plant growth, yield attributes, and yield at harvest were reduced depending on the severity of the Pb stress. Exogenous application of SA improved plant growth and yield. Biochemical data revealed that Pb toxicity resulted in higher oxidative damage by reducing nonenzymatic antioxidants such as ascorbate and glutathione at the higher dose of Pb treatment. Antioxidant enzymes (ascorbate peroxidase – APX, monodehydroascorbate reductase – MDHAR, dehydroascorbate reductase – DHAR, glutathione reductase – GR, guaiacol peroxidase – POD, glutathione S-transferase – GST, and catalase – CAT) responses varied with the Pb doses. Both the nonenzymatic and enzymatic components of the antioxidant defense system were upregulated after application of SA, resulting in lower oxidative damage under Pb-stress conditions. Taken together, the results suggest that exogenous application of the SA mitigates Pb-induced oxidative damage and consequently results in better growth and yield in mustard plants.
Toksyczność ołowiu (Pb) wywiera silny wpływ na wzrost i produktywność roślin. Ochronna rola kwasu salicylowego (SA) jest dobrze znana w warunkach różnych stresów abiotycznych. Jednak niewiele wiadomo na temat indukowanego SA mechanizmu oporności na Pb. W przeprowadzonych badaniach określiliśmy wpływ SA na rośliny gorczycy (Brassica campestris L.) w warunkach stresu wywołanego Pb. Rośliny poddano działaniu trzech poziomów Pb wprowadzonych do gleby (0,25, 0,50, 1,00 mM), z lub bez SA (0,25 mM). Wzrost, wskaźniki plonowania oraz plon roślin uległy zmniejszeniu w zależności od nasilenia stresu indukowanego Pb. Egzogenna aplikacja SA wpłynęła na poprawę wzrostu i plonowania roślin. Wyniki analiz biochemicznych wykazały, że toksyczność Pb powodowała większe uszkodzenia oksydacyjne związane z obniżeniem zawartości nieenzymatycznych antyoksydantów, takich jak askorbinian i glutation, w obecności wyższych stężeń tego metalu. Aktywność enzymów antyoksydacyjnych (peroksydazy askorbinianowej – APX, reduktazy monodehydroaskorbinianowej – MDHAR, reduktazy dehydroaskorbiniano- wej – DHAR, reduktazy glutationowej – GR, peroksydazy gwajakolowej – POD, S-transferazy glutationowej – GST i katalazy – CAT) była uzależniona od stężenia Pb. Zarówno nieenzymatyczne, jak i enzymatyczne elementy systemu obrony antyoksydacyjnej były pozytywnie regulowane po zastosowaniu SA, co powodowało mniejsze uszkodzenia oksydacyjne występujące w warunkach stresu Pb. Podsumowując, uzyskane wyniki sugerują, że egzogenna aplikacja SA łagodzi uszkodzenia oksydacyjne wywołane obecnością Pb, a w konsekwencji prowadzi do lepszego wzrostu i plonowania gorczycy w warunkach ekspozycji na różne poziomy stresu indukowanego Pb.
Źródło:
Acta Agrobotanica; 2019, 72, 2
0065-0951
2300-357X
Pojawia się w:
Acta Agrobotanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Groundwater Contamination and Health Risk Evaluation of Naturally Occurring Potential Toxic Metals of Hatiya Island, Bangladesh
Autorzy:
Rahman, Mahfuzur
Khan, Md. Sadril Islam
Hossain, Mohammad Sabbir
Hossain, Md. Imam Shohel
Hasan, Mahmudul
Hamli, Hadi
Mustafa, M. Golam
Powiązania:
https://bibliotekanauki.pl/articles/2105279.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
drinking water
toxic elements
pollution indices
Hatiya Island
Opis:
Groundwater meets the majority portion of drinking water needs, particularly in the rural area of Bangladesh. Groundwater has been continuously contaminated by potentially harmful metals as a result of natural processes as well as some anthropogenic activities, creating a variety of health impacts. The current research aimed to evaluate the naturally occurring level of metal contamination and the human health risk associated with deep groundwater in the Hatiya Island. Because of the arsenic, iron, and salinity problem in shallow groundwater, the inhabitants of the Hatiya Island use deep groundwater. During the field investigation, no shallow tubewells were observed; therefore, only deep groundwater samples were collected. The total sample size collected throughout the Hatiya island was 17. Five metals (Zn, Fe, Mg, Mn, and Cu) were analyzed using an Atomic Absorption Spectrophotometer (AAS). The concentrations of studied potential risky metals were ranked as follows: Mg > Zn > Fe >Mn> Cu. The detected values of all metals except Fe were found within the drinking water limits of WHO (2017), BIS (2012), and BDWS (1997), where only 29.41% of the Fe sample exceeded the standard drinking limits. According to the metal evaluation index (MEI) and degree of contamination (Cd), the groundwater of the study area is free from contamination but the metal pollution index (MPI) and nemerow pollution index (NI) exhibited little pollution in the mid-western part of the study area. The hazard quotient (HQ) values revealed no oral and dermal health risk for individual metals (Cu, Zn, Fe, Mn). On the other hand, the hazard index (HI) values exhibited no risk for combined metals as none of the values exceeded the safety limit value of 1. According to the HQ and HI results, the deep groundwater on Hatiya Island is non-carcinogenic and risk-free for children and adults. However, children were more susceptible to oral health risks than adults. In contrast, adults were more vulnerable to dermal health risks than children.
Źródło:
Journal of Ecological Engineering; 2022, 23, 6; 223--236
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
In Situ Geothermal Energy Technology: an Approach for Building Cleaner And Greener Environment
Autorzy:
Hossain, M. F.
Powiązania:
https://bibliotekanauki.pl/articles/125344.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
global warming
geothermal energy
construction cost reduction
environmental sustainability
Opis:
Geothermal energy is abundant everywhere in the world. It certainly would be a great benefit for human being once it is produced by a sophisticated technology. Consequently, it would be the biggest console for earth considering environmental sustainability. Unfortunately, the current status of commercial production of geothermal energy primarily from hydrothermal, geopressured, hot dry rock, and magma are limited to a few countries due to technological difficulties and production cost. This paper describes a simple technology where an in situ geothermal plant assisted by a heat pump would act as a high-temperature production (>150°C) to provide excellent capacity of energy generation. The issue related to costs is interestingly cheaper on production, comparing to other technologies, such as solar, hydro, wind, and traditional geothermal technology as described in this article. Therefore, it is suggested that heat pump assisted in situ geothermal energy sources has a great potentiality to be a prime energy source in near future. Since the technology has a number of positive characteristics (simple, safe, and provides continuous baseload, load following, or peaking capacity) and benign environmental attributes (zero emissions of CO2, SOx, and NOx), it certainly would be an interesting technology in both developed, and developing countries as an attractive option to produce clean energy to confirm a better environment.
Źródło:
Journal of Ecological Engineering; 2016, 17, 1; 49-55
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
In Situ Solution Process for Fabricating Thermally and Mechanically Stable Highly Conductive ZnO-CNT Fiber Composites
Autorzy:
Hossain, M.
Son, S.
Hahn, J.
Powiązania:
https://bibliotekanauki.pl/articles/1033363.pdf
Data publikacji:
2017-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.-t
Opis:
A simple in situ solution process was developed to produce a mechanically and thermally stable ZnO-carbon nanotube fiber composite. ZnO nanoparticles were homogeneously deposited onto the surfaces of and interstices within CNT fibers (between individual CNTs). X-ray photoelectron spectroscopy and Raman analysis revealed that ZnO nanoparticles contained oxygen vacancy defects and CNT fibers included oxygen containing functional group that strongly interacted with Zn. The strong interaction enhanced the mechanical properties of the composite fibers. The Young modulus (20 GPa) and tensile strength (118 MPa) were enhanced compared to the corresponding values of the pristine CNT fibers. The thermal stability was high up to 880°C and light absorption was enhanced across the UV to near IR region in a ZnO-CNT fiber composite. The electrical conductivity of the composite was high up to 954 S/cm despite semiconductor deposition.
Źródło:
Acta Physica Polonica A; 2017, 131, 1; 124-132
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mathematical Modelling of Dynamic Yarn Path Considering the Balloon Control Ring and Yarn Elasticity in the Ring Spinning Process Based on the Superconducting Bearing Twisting Element
Matematyczne modelowanie dynamicznej trajektorii przędzy z uwzględnieniem pierścienia sterującego balonem i elastyczności przędzy w procesie przędzeniaobrączkowego opartego na nadprzewodzącym elemencie skręcającym łożyska
Autorzy:
Hossain, M.
Telke, C.
Abdkader, A.
Sparing, M.
Espenhahn, T.
Hühne, R.
Cherif, C.
Beitelschmidt, M.
Powiązania:
https://bibliotekanauki.pl/articles/232337.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
mathematical modelling
balloon control ring
yarn elasticity
yarn tension
balloon form
ring spinning
superconducting magnetic bearing
modelowanie matematyczne
pierścień sterujący balonem
elastyczność przędzy
napięcie przędzy
kształt balonu
wirowanie pierścieniowe
nadprzewodzące łożysko magnetyczne
Opis:
The productivity of the conventional ring spinning process is currently limited by the frictional heat that occurs in the ring/traveler twisting system. In the framework of a fundamental research project from the German Research Foundation (DFG), the levitation principle of superconducting magnetic bearing (SMB) was implemented as a twisting element in order to eliminate the frictional problem and thus aim, at least, to double the productivity. A mathematical model of the dynamic yarn path has already been presented considering the friction free SMB system up to an angular spindle speed of 25.000 r.p.m. In this paper, the existing theoretical model, which was developed up to 25.000 r.p.m, was further modified considering the balloon control ring and yarn elasticity at a higher angular spindle speed, such as 50.000 r.p.m. The model was solved numerically using the Runge-Kutta method. With this model, it is possible to estimate the yarn tension distribution and balloon form considering the above-mentioned parameters. The model established was further validated by comparing the yarn tension and balloon forms predicted with measured ones up to an angular spindle speed of 15.000 r.p.m in a ring spinning tester based on superconducting magnetic bearing.
Wydajność konwencjonalnego procesu przędzenia obrączkowego jest ograniczana przez ciepło tarcia występujące w układzie skręcania pierścień /wahadło. W ramach projektu badawczego z Niemieckiej Fundacji Badawczej (DFG) wprowadzono zasadę lewitacji nadprzewodzącego łożyska magnetycznego (SMB) jako elementu skręcającego w celu wyeliminowania problemu tarcia. Celem pracy było przynajmniej podwojenie wydajność. Przedstawiono model matematyczny dynamicznej trajektorii przędzy z uwzględnieniem systemu SMB bez tarcia, przy prędkości obrotowej wrzeciona 25.000 obr./min. Nastęnie istniejący del teoretyczny został dodatkowo zmodyfikowany, a przy modyfikacji wzięto pod uwagę pierścień kontrolny balonu i elastyczność przędzy przy wyższej prędkości obrotowej wrzeciona tj. 50.000 obr./min. Model został rozwiązany numerycznie za pomocą metody RUNGE-KUTTA. W tym modelu możliwe jest oszacowanie rozkładu naprężenia przędzy i kształtu balonu z uwzględnieniem wyżej wymienionych parametrów. Ustalony model został dodatkowo zweryfikowany poprzez porównanie naprężenia przędzy i przewidywanych form balonu. W tym celu użyto testera przędzenia obrączkowego opartego na nadprzewodzącym łożysku magnetycznym.
Źródło:
Fibres & Textiles in Eastern Europe; 2018, 5 (131); 32-40
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Measurement methods of dynamic yarn tension in a ring spinning process
Metody pomiaru naprężeń przędz w stanie dynamicznym w przędzarce obrączkowej
Autorzy:
Hossain, M.
Abdkader, A.
Nocke, A.
Unger, R.
Krzywinski, F.
Hasan, M. M. B.
Cherif, C.
Powiązania:
https://bibliotekanauki.pl/articles/232351.pdf
Data publikacji:
2016
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
balloon tension
ring spinning
winding tension
measurement method
przędzenie obrączkowe
naprężenie przędzy
strefa skręcania
strefa balonu
metoda pomiaru
Opis:
The most common measuring method to characterise the dynamic yarn path in the ring spinning process is to measure the yarn tension, where the yarn path is almost straight. However, it is much more complex to measure the yarn tension at the other positions, for example, between the yarn guide and traveller (balloon zone) and between the traveller and winding point of the cop (winding zone), as the yarn rotates continuously around the spindle axis. In this paper, two new methods of yarn tension measurement in the balloon zone are proposed. In the first method, the balloon shape was first recorded with a high speed camera. The balloon tension was then calculated by comparing the yarn strain (occurring in the balloon zone) measured by a digital image analysis program with the stress-strain curve of the yarn produced. In the second method, the radial forces of the rotating balloon were measured by using modified measurement techniques for measurement of yarn tension. Moreover a customised sensor was developed to measure the winding tension between the traveller and cop. The values measured were validated with a theoretical model and a good correlation between the measured and theoretical values could be revealed.
Najczęściej stosowaną metodą pomiarową dla scharakteryzowania dynamiki przędzy podczas przędzenia obrączkowego jest pomiar naprężenia przędzy w miejscu gdzie jej przebieg jest prawie prostoliniowy. Jednakże znacznie bardziej skomplikowany jest pomiar naprężenia przędzy pomiędzy prowadnikiem i biegaczem (strefa balonu) oraz pomiędzy biegaczem i punktem skręcania przed cewką nawojowa (strefa skręcania) ponieważ przędza wiruje w sposób ciągły wokół osi wrzeciona. W pracy przedstawiono dwie nowe metody pomiaru naprężenia przędzy w strefie balonu. W pierwszej wstępnie określano kształt balonu za pomocą kamery o dużej prędkości powtarzania. Następnie określano naprężenie balonu przez porównanie odkształceń przędzy powstających w strefie balonu a mierzonych za pomocą cyfrowej analizy obrazu i programu wykorzystującego krzywą zależności naprężenie-odkształcenie produkowanej przędzy. W drugiej metodzie promieniowe siły wirującego balonu były mierzone przy zastosowaniu zmodernizowanej techniki pomiaru naprężenia przędzy. Pomierzone wartości były porównywane z wartościami modelu teoretycznego przy czym stwierdzono istnienie bardzo dobrej korelacji.
Źródło:
Fibres & Textiles in Eastern Europe; 2016, 1 (115); 36-43
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preconditiong and Inoculation of Low Sulphur Grey Iron
Autorzy:
Hossain, Md Sojib S.
Bazlur B. Rashid, A. K. M.
Powiązania:
https://bibliotekanauki.pl/articles/380548.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
grey iron
metallography
mechanical properties
cementite
preconditioner
inoculant
żeliwo szare
metalografia
właściwości mechaniczne
cementyt
Opis:
For quality grey cast iron production, the challenging issues are to avoid cementite structure and obtain the desired graphite morphology with proper matrix as well as hardness. The objective of the present research is to find out the right combination of preconditioner and inoculant that may help to overcome the challenges. In this work, sulphur content is kept low (0.01%). Two preconditioners namely metallurgical SiC and zirconium bearing FeSi with two types of inoculant are individually used to make four combinations of sample and for each case metal is poured into the green sand mould. Finally Brinell hardness and graphite morphology is observed in the thickest and thinnest portions of the castings. Metallurgical SiC with barium bearing inoculant gives better graphite morphology and hardness than strontium bearing inoculant, on the other hand zirconium bearing FeSi gives more satisfying result than SiC with every type of inoculant. Among all of the combinations Zr bearing preconditioner with Ba bearing inoculant gives good graphite morphology with best mechanical properties in both thickest and thinnest portions of the casting.
Źródło:
Archives of Foundry Engineering; 2020, 20, 1; 61-66
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 19

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