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 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

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

Pervaporation of hydrazine/water with ethylcellulose/4A zeolite mixed matrix membranes

Uma Maheshwari Peddoddi,Dilip Kumar Behara,Suggala Venkata Satyanarayana 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.11

Hydrazine, a hygroscopic liquid, needs to be dehydrated for its utilization as rocket propellant. The conventional processes of separation are cumbersome, as hydrazine forms an azeotrope with water apart from being explosive and highly alkaline. Pervaporation is a well-established safe, energy intensive process for separation of azeotrope mixtures. The selection of polymer for separation of hydrazine and water is of major concern as hydrazine is highly alkaline with pH of ~13.6. Ethyl cellulose (EC) polymer withstands the high pH without any physical deformation or color change. Further, to increase the permselectivity, zeolite 4A nanoparticles were incorporated into the EC polymer matrix. The major focus of the present study was synthesis of zeolite 4A nanoparticles and preparation of ethyl cellulose- zeolite 4A mixed matrix membranes (MMMs). The zeolite particles and membranes were characterized using XRD and FTIR. The characteristics of the membranes were further observed by measuring contact angles. The pervaporation results were quite promising as the total permeate flux and selectivity were 18.35 g/m2h and 8.46 at 36 wt% of feed water concentration with the MMMs with highest zeolite loading. The performance of the MMM’s was comparatively better than pristine EC.

Seismic design of beam-column joints in RC moment resisting frames - Review of codes

Uma, S.R.,Jain, Sudhir K. Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.23 No.5

The behaviour of reinforced concrete moment resisting frame structures in recent earthquakes all over the world has highlighted the consequences of poor performance of beam column joints. Large amount of research carried out to understand the complex mechanisms and safe behaviour of beam column joints has gone into code recommendations. This paper presents critical review of recommendations of well established codes regarding design and detailing aspects of beam column joints. The codes of practice considered are ACI 318M-02, NZS 3101: Part 1:1995 and the Eurocode 8 of EN 1998-1:2003. All three codes aim to satisfy the bond and shear requirements within the joint. It is observed that ACI 318M-02 requires smaller column depth as compared to the other two codes based on the anchorage conditions. NZS 3101:1995 and EN 1998-1:2003 consider the shear stress level to obtain the required stirrup reinforcement whereas ACI 318M-02 provides stirrup reinforcement to retain the axial load capacity of column by confinement. Significant factors influencing the design of beam-column joints are identified and the effect of their variations on design parameters is compared. The variation in the requirements of shear reinforcement is substantial among the three codes.

A New Fuzzy Logic and GSO based Load balancing Mechanism for Public Cloud

Uma Singhal,Sanjeev Jain 보안공학연구지원센터 2014 International Journal of Grid and Distributed Comp Vol.7 No.5

The recent advances in cloud computing set up well established research in Distributed computing, virtualization, web services, utility computing, have offered many benefits in scalability, cost and efficiency for cloud service users. These advantages are further expected to fulfill the demands of cloud users for cloud services efficiently. This brings the problem of fault tolerance, scalability, efficiency, high availability. Central to these issues require the dynamic and efficient load balancing techniques. In this paper, an effective load balance model is presented for public cloud in which cloud is partitioned with a switch mechanism to choose different load balancing strategy for different load. Fuzzy Logic have been extensively used in various applications such as image processing, data mining, networking, etc. due to its efficient internal architecture and its compatibility to solve various optimization problems. Fuzzy base networks have been observed to produce optimal results in various combinatorial optimization problems. Another important area which provides significant results in solving optimization is the swarm intelligence approach. GSO is observed to have provided significant optimal solution in lesser iterations. In this paper The Fuzzy logic and GSO based load balancing algorithm applied to the load balancing strategy to enhance the utilization and efficiency in the public cloud environment.

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

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.

Clarification, Preservation, and Shelf Life Evaluation of Cashew Apple Juice

Uma Talasila,Rama Rao Vechalapu,khasim beebi shaik 한국식품과학회 2012 Food Science and Biotechnology Vol.21 No.3

Cashew apples are tropical fruits rich in sugars,minerals, and vitamin C. In spite of having high nutritional value, neither the fresh cashew apples nor the juice is consumed due to astringency. In the present investigation an attempt was made to reduce the astringency without affecting the nutrient quality of the juice. The clarifying agent, sago at a concentration of 2 g/L, has decreased the tannins by 42.85% but the respective sample’s visual clarity is only 94%. The same clarifying agent with the same concentration along with sterile filtration has decreased the tannins by 41.75% with improved visual clarity of 96%. This clarified juice sample was treated with chemical preservatives and the quality of the juice was assessed periodically up to 4 months. The shelf life of juice treated with citric acid and benzoic acid at 0.1 g/L each and stored at 4oC was prolonged up to 90 days.

Synthesis of novel dinuclear europium dye complex for their optical properties

( Uma Ravi Sankar Arigala ),( Min Su Park ),( Kuk Ro Yoon ) 한국화상학회 2010 한국화상학회지 Vol.16 No.4

A novel organic ligand, 9,11,20,22-tetraaza tetrapyrido pentacene (TATPP), and the corresponding europium complex, [Eu2 (TTA)6(TATPP)] have been designed and synthesized. The results showed that [Eu2 (TTA)6(TATPP)] was a conjugated complex, emitting remarkably strong red luminescence. The lifetimes of 5D0 of Eu3+ in the complex were examined using time-resolved spectroscopic analysis; the lifetime values were 3.25x106M) Eu2 (TTA)6(TATPP) ethanol solution, respectively. Thermo gravimetric analysis showed the europium complex had good thermal stability.

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