Equilibrium and kinetic studies for removal of malachite green from aqueous solution by a low cost activated carbon

Uma,Yogesh C. Sharma,Sushmita Banerjee 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.4

A low cost activated carbon was synthesized from coconut coir and was applied for the removal of malachite green (MG) from its aqueous solutions. Characterization of the adsorbent was carried out and BET surface area of the adsorbent was found to be 205.27 m2/g. The process of removal of MG was better governed by second order kinetics with a rate constant of 0.21 g mgˉ1 minˉ1 at 323 K. The coefficient of mass transfer was found to be 3.70 x10ˉ5 cm sˉ1. The value of DG8 was found to be negative indicating feasibility and spontaneity of the adsorption process.

Adaptive Distance Protection Scheme for Mutually Coupled Line

Uma Uzubi Uma,Arthur Ekwue,Emenike Ejiogu 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.1

The availability of zero-sequence current, under normal circumstances, determines the accuracy of the operation of a distance relay which is connected to a mutually coupled parallel line. When this is not available, the system adopts a diff erent compensation factor which if, not properly calculated introduces errors in the relay operation. The proposed adaptive protection scheme, described in this paper, consists of three modular artifi cial neural networks model (ANN). This is developed using the feed-forward nonlinear backpropagation Levenberg–Marquardt algorithm that determines the actual status of the mutually coupled lines. The remote terminal units connected to the current and voltage transformers are used to acquire the appropriate data. The proposed scheme also carefully determines the ground distance element reach settings by calculating the apparent impedance while considering mutual coupling for all practical system confi gurations from the ANN; this eliminates the need for a compensation factor. The results of the apparent impedance (R + jX) calculated by the proposed adaptive and the conventional schemes, showed an average percentage error of (0.06% and 0.02%) and (15% and 41.5%) respectively. Having obtained this result, the performance of the proposed adaptive scheme showed the exact fault location with a higher accuracy when compared with a compensated conventional scheme

Adaptive Distance Protection Scheme Setting in Presence of SVC Using Remote Terminal Unit

Uma Uma Uzubi,Ekwue Arthur,Nmadu Daniel,Eli-Chukwu Ngozi Clara 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.4

FACTS devices are presently used to improve the power transfer capability of a transmission line and voltage stability of a power system network. Shunt injected current (I sh ) by the Static Var Compensators (SVC) causes underreach or overreach of distance relay when not considered during relay calibration of protection system. This paper presents an adaptive relay setting procedure in the presence of a SVC connected at the midpoint of a transmission line. The remote terminal unit RTU is connected to the SVC terminal via a current transformer (CT) measures the injected shunt current when the SVC is the switch in or out of the network and transferred the measured value to the local station via fi ber optic. The PSCAD/ EMTDC software is used to model an adaptive relay that implements the conventional and adaptive relay system settings. The proposed scheme presents a hybrid distance protection system whose setting is based on the prevailing SVC switching conditions; the relay system was implemented using mho characteristics relay. The results obtained show that the proposed scheme has a high accurate setting

ENABLING UNASSISTED VISIBLE SOLAR WATER SPLITTING VIA GREEN AND EFFICIENT EUTECTIC MEDIATED QUANTUM DOT SENSITIZED PHOTOELECTRODES

Uma V. Ghorpade,Jin Hyeok Kim 한국신재생에너지학회 2017 AFORE Vol.2017 No.11

Foliar Application of Magnesium Sulphate and Basal Application of Calcium Carbonate A New Dimension in Production of Tasar Crops

( Uma S P Sinha ),( Susmita Das ),( Manoj K Sinha ) 한국잠사학회 2012 International Journal of Industrial Entomology Vol.25 No.1

An experiment was carried out to boost the production of tasar crops through application of secondary nutrients. Different combinations of secondary nutrients were prepared and its effect was studied on the yield and quality of leaves of tasar food plant Terminalia tomentosa W & A with 2.4 m × 2.4 m spacing and cocoon characters of tasar silkworm Antheraea mylitta Drury reared on them. Among different combinations of secondary nutrients, foliar application of magnesium sulphate (2%, w/v) and basal application of 3 quintal / ha of calcium carbonate (secondary nutrient combination SM5) was found to be the best in crop improvement. It improves the quantity and quality of leaves as well as the commercial characters of cocoons. As a result, silk production improves. Under this combination, leaf yield increased by 26.55% in comparison to control. Average increase in moisture, total mineral, crude protein and total carbohydrate was 3.26%, 20.84%, 15.39% and 17.85% respectively as compared with control. Further, bio assay studies revealed thataverage larval weight, E.R.R., cocoon weight, shell weight and silk ratio percent increased by 11.25%, 25.71%, 20.05%, 35.14% and 12.17% respectively over control which indicates that secondary nutrient combination SM5 has significant role in improving the production of tasar crops.

디지털 플랫폼과 일의 세계 : 도전과 기회

Uma Rani 한국노동연구원 2022 국제노동브리프 Vol.20 No.4

Video of World Festivals as Novelties in Teaching Description Writing Using a Genre-Based Approach

( Uma Maheswari Rajagopalan ) 범태평양응용언어학회 2017 범태평양응용언어학회지 Vol.21 No.1

In order to motivate ESL students and engage them in different tasks effectively, it is necessary to make the tasks novel to the students. As one possible way of introducing novelty in the course, films could be used advantageously. In this study, a writing course integrated with videos of movies and cultural festival of different regions of the world including that of author`s country were used as a novel activity and students` attitudes were investigated through questionnaire and open-ended comments. The students belonged to second year undergraduate course of food and nutrition sciences of a Japanese private university. In addition to the film videos as part of listening activity, students were introduced to writings of different genres such as autobiographical, general description, procedure and argumentative writings using a genre-based approach. Students were first introduced to a model writing followed by deconstructing the model writing based on a set of questions. Next, students were asked to write based on the questions to make an outline of their own writings. Following making an outline in the classroom, students constructed their own one paragraph essays. Effects of learning were assessed through students` engagement in writing and in class questionnaire on the video. It was found that students showed real interest in watching film and cultural festivals videos. With cultural festivals, students were made to make comparison with their own and report describing the interesting feature of the festival. The students were also asked to critically reflect on the festivals themselves. Because of the novelty, students actively engaged in the class making the class interesting to the students. In future, a more detailed curriculum using festivals from different parts of their country along with festivals from different parts of the world could be worth considering.

ON FUZZY ${\beta}-COMPACT^*$ SPACES AND FUZZY $\beta$-FILTERS

Uma, M.K.,Roja, E.,Balasubramanian, G. The Youngnam Mathematical Society Korea 2007 East Asian mathematical journal Vol.23 No.2

In this paper we introduce the concept of fuzzy ${\beta}-compact^*$ spaces. Besides giving some interesting properties of fuzzy ${\beta}-compact^*$ spaces we also give a characterization on fuzzy $\beta$-compact spaces by making use of newly introduced concept of fuzzy $\beta$-filters.

그래핀 옥사이드 표면에 di nuclear europium complexes가 도입된 하이브리드 소재 합성

( Uma Ravi Sankar Arigala ),임병철 ( Byung Chul Lim ),윤옥자 ( Yoon Ja Ok ),이내응 ( Nae Eung Lee ),윤국로 ( Kuk Ro Yoon ) 한국화상학회 2012 한국화상학회지 Vol.18 No.4

유러피언(Eu) 착물을 이용하여 산화 그래핀 시트와 비공유 결합방법을 이용하여 제조 하였으며, 산화 그래핀(GOS)뿐만 아니라 혼합된 각각의 물질의 특성을 유러피언(Eu) 착물의 흡착을 확인하였다. 또한, 하이브리드 산화 그래핀(GOS)-유러피언(Eu) 착물의 최종 생성물은 생물학적 labeling과 anti-counterfeiting등 여러 실용적인 분야에 적용 가능한 밝은 적색의 발광을 방출하는 물질이다. Graphene oxide sheets (GOSs) functionalized with Europium complex was prepared using a noncovalent approach. The adsorption of Europium complexes onto GOSs, as well as the individual nature of the hybrids, was confirmed. The GOS-Europium complex hybrids and their dispersion can emit bright red luminescence, which makes them useful in many practical fields, such as biological labeling and anti-counterfeiting.

Synthesis and Characterization of Sodium-Iron Antimonate Na₂FeSbO₅: One-Dimensional Antiferromagnetic Chain Compound with a Spin-Glass Ground State

Uma, Sitharaman,Vasilchikova, Tatyana,Sobolev, Alexey,Raganyan, Grigory,Sethi, Aanchal,Koo, Hyun-Joo,Whangbo, Myung-Hwan,Presniakov, Igor,Glazkova, Iana,Vasiliev, Alexander,Streltsov, Sergey,Zvereva, American Chemical Society 2019 Inorganic chemistry Vol.58 No.17

<P>A new oxide, sodium-iron antimonate, Na<SUB>2</SUB>FeSbO<SUB>5</SUB>, was synthesized and structurally characterized, and its static and dynamic magnetic properties were comprehensively studied both experimentally by <I>dc</I> and <I>ac</I> magnetic susceptibility, magnetization, specific heat, electron spin resonance (ESR) and Mössbauer measurements, and theoretically by density functional calculations. The resulting single-crystal structure (<I>a</I> = 15.6991(9) Å; <I>b</I> = 5.3323 (4) Å; <I>c</I> = 10.8875(6) Å; S.G. <I>Pbna</I>) consists of edge-shared SbO<SUB>6</SUB> octahedral chains, which alternate with vertex-linked, magnetically active FeO<SUB>4</SUB> tetrahedral chains. The <SUP>57</SUP>Fe Mössbauer spectra confirmed the presence of high-spin Fe<SUP>3+</SUP> (3d<SUP><I>5</I></SUP>) ions in a distorted tetrahedral oxygen coordination. The magnetic susceptibility and specific heat data show the absence of a long-range magnetic ordering in Na<SUB>2</SUB>FeSbO<SUB>5</SUB> down to 2 K, but <I>ac</I> magnetic susceptibility unambigously demonstrates spin-glass-type behavior with a unique two-step freezing at <I>T</I><SUB>f1</SUB> ≈ 80 K and <I>T</I><SUB>f2</SUB> ≈ 35 K. Magnetic hyperfine splitting of <SUP>57</SUP>Fe Mössbauer spectra was observed below <I>T</I>* ≈ 104 K (<I>T</I><SUB>f1</SUB> < <I>T</I>*). The spectra just below <I>T</I>* (<I>T</I><SUB>f1</SUB> < <I>T</I> < <I>T</I>*) exhibit a relaxation behavior caused by critical spin fluctuations, indicating the existence of short-range correlations. The stochastic model of ionic spin relaxation was used to account for the shape of the Mössbauer spectra below the freezing temperature. A complex slow dynamics is further supported by ESR data revealing two different absorption modes presumably related to ordered and disordered segments of spin chains. The data imply a spin-cluster ground state for Na<SUB>2</SUB>FeSbO<SUB>5</SUB>.</P><P>A new oxide, sodium−iron antimonate, Na<SUB>2</SUB>FeSbO<SUB>5</SUB>, was synthesized, and its structural and magnetic properties were studied. The system does not undergo a long-range magnetic order in agreement with the fact that it is a one-dimensional magnetic chain system. The mapping analysis based on density functional theory calculations shows a strong one-dimensional, antiferromagnetic intrachain exchange coupling of ∼200 K.</P> [FIG OMISSION]</BR>