Towards Versatile Continuous-Flow Chemistry and Process Technology Via New Conceptual Microreactor Systems

Ramanjaneyulu, Bandaru T.,Vishwakarma, Niraj K.,Vidyacharan, Shinde,Adiyala, Praveen Reddy,Kim, Dong-Pyo Korean Chemical Society 2018 Bulletin of the Korean Chemical Society Vol.39 No.6

In the past decade, microreaction technology has been attracted much attention to the scientific community as one of the subareas in chemical synthesis. The microreactor improves the yield with higher selectivity, and also facilitates the reactions by simple, safe, fast, and green approaches. This review gives an overview on our contributions to develop versatile continuous-flow syntheses and process technology by exampling gas-liquid binary phase in modified PDMS microreactors, and process intensification for safe operation of toxic/hazardous chemistry by generating hazardous chemicals to end utilization via various separation techniques in newly devised systems as well as ordinary capillary reactors. Furthermore, it covers process technology for ultrafast organic synthesis such as submillisecond control of short-lived intermediates in a polyimide chip reactor. These works provide outlooks for integrated and automated flow chemistry via one-flow/feed to end concept, i.e., useful in pharmaceutical industry, toward enabling new and innovative chemistry beyond limits of a batch reactor.

Simplified computational methodology for analysis and studies on behaviour of incrementally launched continuous bridges

K. Ramanjaneyulu,V. Srinivas,S. Gopalakrishnan,Saptarshi Sasmal 국제구조공학회 2004 Structural Engineering and Mechanics, An Int'l Jou Vol.17 No.2

Simplified computational methodology for analysis and studies on behaviour of incrementally launched continuous bridges

Sasmal, Saptarshi,Ramanjaneyulu, K.,Srinivas, V.,Gopalakrishnan, S. Techno-Press 2004 Structural Engineering and Mechanics, An Int'l Jou Vol.17 No.2

Incremental launching method is one of the highly competitive techniques for construction of concrete bridges. It avoids costly and time consuming form work and centralizes all construction activities in a small casting yard, thus saving in cost and time against conventional bridge construction. From the quality point of view, it eliminates the uncertainty of monolithic behaviour by allowing high repetitiveness and industrial environment. But, from analysis and design point of view, the most characteristic aspect of incrementally launched bridges is that, it has to absorb the stresses associated with the temporary supports that are gradually taken on by the deck during its launch. So, it is necessary to analyse the structure for each step of launching which is a tedious and time consuming process. Effect of support settlements or temperature variation makes the problem more complex. By using transfer matrix method, this problem can be handled efficiently with minimal computational effort. This paper gives insight into method of analysis, formulation for optimization of the structural system, effect of support settlement and temperature gradient, during construction, on the stress state of incrementally launched bridges.

Effective CFRP retrofit strategy for flexural deficient RC beams

Nawal Kishor Banjara,K. Ramanjaneyulu 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.69 No.2

Structural deterioration arises due to aging, environmental effects, deficiencies during design and construction phase, and overloading. Experimental and numerical investigations are carried out in this study to evaluate the performance of control and flexural deficient reinforced concrete (RC) beams under monotonic loading. Three levels of flexural deficiency are considered in this study. After confirming load carrying capacities of control and flexural deficient beams, the flexural deficient RC beams are strengthened with carbon fibre reinforced polymer (CFRP) fabric. CFRP strengthened RC beams are tested under monotonic loading and compared with the performance of control specimen. Further, non-linear finite element analyses are also carried out to evaluate the flexural performance of control, deficient and CFRP strengthened flexural deficient RC beams. There is good correlation between results of experimental and numerical investigations. Numerical approach presented in this study can be adopted for assessing the adequacy of CFRP retrofit measure.

Energy harvesting of PZT/PMMA composite flexible films

K. Thanigai Arul,M. Ramanjaneyulu,M.S. Ramachandra Rao 한국물리학회 2019 Current Applied Physics Vol.19 No.4

Polymer/lead zirconate titanate {[Pb(Zrx, Ti1-x)O3], PZT, x=0.40} flexible composite films are prepared by solvent evaporation technique. Carbon tape used as a top and bottom electrodes for fabricating flexible PZT composite films. The phase purity and functional groups of PZT and polymer humps are confirmed by XRD and FTIR respectively. XPS analysis showed that PMMA contains carbon (C) and oxygen (O). Carbon (C), oxygen (O), lead (Pb), zirconium (Zr) and titanium (Ti) are present in PZT/PMMA composite films. The chemical states of Pb, Zr and Ti ions are 2+, 4+ and 4+ respectively confirmed by XPS. The higher forefinger bending motion of the film is found to reveal greater output voltage (5.2 V) than the output voltage (1.6 V) for slight bending motion of the forefinger. Therefore, based on the results human mechanical forces induce compressive stress on PZTs ferroelectric based composite films and are excellent candidate for energy harvester.

Non-invasive steel haunch upgradation strategy for seismically deficient reinforced concrete exterior beam-column sub-assemblages

A. Kanchanadevi,K. Ramanjaneyulu 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.6

Prior to the introduction of modern seismic guidelines, it was a common practice to provide straight bar anchorage for beam bottom reinforcement of gravity load designed building. Exterior joints with straight bar anchorages for beam bottom reinforcements are susceptible to sudden anchorage failure under load reversals and hence require systematic seismic upgradation. Hence in the present study, an attempt is made to upgrade exterior beam-column sub-assemblage of a three storied gravity load designed (GLD) building with single steel haunch. Analytical formulations are presented for evaluating the haunch forces in single steel haunch retrofit. Influence of parameters that affect the efficacy and effectiveness of the single haunch retrofit are also discussed. The effectiveness of the single haunch retrofit for enhancing seismic performance of GLD beam-column specimen is evaluated through experimental investigation under reverse cyclic loading. The single steel haunch retrofit had succeeded in preventing the anchorage failure of beam bottom bars of GLD specimen, delaying the joint shear damage and partially directing the damage towards the beam. A remarkable improvement in the load carrying capacity of the upgraded GLD beam-column sub-assemblage is observed. Further, a tremendous improvement in the energy dissipation of about 2.63 times that of GLD specimen is observed in the case of upgraded GLD specimen. The study also underlines the efficacy of single steel haunch retrofit for seismic upgradation of deficient GLD structures.

Exposure to elevated temperatures and cooled under different regimes-a study on polypropylene concrete

Yaragal, Subhash C.,Ramanjaneyulu, S. Techno-Press 2016 Advances in materials research Vol.5 No.1

Fire is one of the most destructive powers to which a building structure can be subjected, often exposing concrete elements to elevated temperatures. The relative properties of concrete after such an exposure are of significant importance in terms of the serviceability of buildings. Unraveling the heating history of concrete and different cooling regimes is important for forensic research or to determine whether a fire-exposed concrete structure and its components are still structurally sound or not. Assessment of fire-damaged concrete structures usually starts with visual observation of colour change, cracking and spalling. Thus, it is important to know the effect of elevated temperatures on strength retention properties of concrete. This study reports the effect of elevated temperature on the mechanical properties of the concrete specimen with polypropylene fibres and cooled differently under various regimes. In the heating cycle, the specimen were subjected to elevated temperatures ranging from $200^{\circ}C$ to $800^{\circ}C$, in steps of $200^{\circ}C$ with a retention period of 1 hour. Then they were cooled to room temperature differently. The cooling regimes studied include, furnace cooling, air cooling and sudden cooling. After exposure to elevated temperatures and cooled differently, the weight loss, residual compressive and split tensile strengths retention characteristics were studied. Test results indicated that weight and both compressive and tensile strengths significantly reduce, with an increase in temperature and are strongly dependent on cooling regimes adopted.

Novel steel bracket and haunch hybrid system for post-earthquake retrofit of damaged exterior beam-column sub-assemblages

A. Kanchanadevi,K. Ramanjaneyulu 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.73 No.3

In the present study, an innovative steel bracket and haunch hybrid scheme is devised, for retrofitting of earthquake damaged deficient beam-column sub-assemblages. Formulations are presented for evaluating haunch force factor under combined load case of lateral and gravity loads for the design of double haunch retrofit. The strength hierarchies of control and retrofitted beam-column sub-assemblages are established to showcase the efficacy of the retrofit in reversing the undesirable strength hierarchy. Further, the efficacy of the proposed retrofit scheme is demonstrated through experimental investigations carried out on gravity load designed (GLD), non-ductile and ductile detailed beam-column sub-assemblages which were damaged under reverse cyclic loading. The maximum load carried by repaired and retrofitted GLD specimen in positive and negative cycle is 12% and 28% respectively higher than that of the control GLD specimen. Further, the retrofitted GLD specimen sustained load up to drift ratio of 5.88% compared with 2.94% drift sustained by control GLD specimen. Repaired and retrofitted non-ductile specimen, could attain the displacement ductility of three during positive cycle of loading and showed improved ductility well above the expected displacement ductility of three during negative cycle. The hybrid haunch retrofit restored the load carrying capacity of damaged ductile specimen to the original level of control specimen and improved the ductility closer to the expected displacement ductility of five. The total cumulative energy dissipated by repaired and retrofitted GLD, non-ductile and ductile specimens are respectively 6.5 times, 2.31 times, 1.21 times that of the corresponding undamaged control specimens. Further, the damage indices of the repaired and retrofitted specimens are found to be lower than that of the corresponding control specimens. The novel and innovative steel bracket and haunch hybrid retrofit scheme proposed in the present study demonstrated its effectiveness by attaining the required displacement ductility and load carrying capacity and would be an excellent candidate for post-earthquake retrofit of damaged existing RC structures designed according to different design evolutions.

Numerical analysis of under-designed reinforced concrete beam-column joints under cyclic loading

Saptarshi Sasmal,Balthasar Novák,K. Ramanjaneyulu 사단법인 한국계산역학회 2010 Computers and Concrete, An International Journal Vol.7 No.3

In the present study, exterior beam-column sub-assemblage from a regular reinforced concrete (RC) building has been considered. Two different types of beam-column sub-assemblages from existing RC building have been considered, i.e., gravity load designed (‘GLD’), and seismically designed but without any ductile detailing (‘NonDuctile’). Hence, both the cases represent the under-designed structure at different time frame span before the introduction of ductile detailing. For designing ‘NonDuctile’ structure, Eurocode and Indian Standard were considered. Non-linear finite element (FE) program has been employed for analysing the sub-assemblages under cyclic loading. FE models were developed using quadratic concrete brick elements with embedded truss elements to represent reinforcements. It has been found that the results obtained from the numerical analysis are well corroborated with that of experimental results. Using the validated numerical models, it was proposed to correlate the energy dissipation from numerical analysis to that from experimental analysis. Numerical models would be helpful in practice to evaluate the seismic performance of the critical sub-assemblages prior to design decisions. Further, using the numerical studies, performance of the sub-assemblages with variation of axial load ratios (ratio is defined by applied axial load divided by axial strength) has been studied since many researchers have brought out inconsistent observations on role of axial load in changing strength and energy dissipation under cyclic load.

Enhancing Performance of Dual-Gate FinFET with High-K Gate Dielectric Materials in 5 nm Technology: A Simulation Study

M. V. Ganeswara Rao,N. Ramanjaneyulu,Balamurali Pydi,Umamaheshwar Soma,K. Rajesh Babu,Satti Harichandra Prasad 한국전기전자재료학회 2023 Transactions on Electrical and Electronic Material Vol.24 No.6

The rapid advancement in nanoscale devices demands innovative gate dielectric materials to replace traditional Silicon dioxide. This paper investigates the electrical behavior and performance of a dual-gate FinFET employing different high-K gate dielectric materials (Silicon dioxide, Hafnium oxide, Titanium oxide) through ATLAS 2D simulation in 5 nm technology. We analyze how these high-K gate dielectric materials influence the device, focusing on performance enhancement. The study highlights various key performance parameters (ION, IOFF, gm, gds, RON, TF, EV, V IL, V IH, NML, NMH) and reveals a significant performance improvement with HfO2 dielectric material in the proposed Dual-Gate FinFET. Achieving impressive performance parameters ( ION : 21.59 mA, IOFF : 21 µA, Maximum net Electric field: 1221290 V/cm, g m(max) : 0.05187 S, gds(max) : 0.03462 S, RON(max) : 25.93 kΩ , TFmax: 5.02, G ainmax : 90.233, EVmax : 67.532 V, V IL : 0.21 V, V IH : 0.4 V, NML : 198 V, NMH : 600 V), this paper provides valuable insights for designing high-performance devices with HfO2 dielectric material.