A Novel Comparative Approach for Estimating Maximum Penetration Capacity of Grid Connected Solar Photovoltaic System in Distribution Network

Sreekumar Sreena,Savier J. S. 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.5

Solar Photovoltaic Generation (SPVG) system is one of the key strategies in meeting growing challenges in the energy front. Advantages from these energy sources can be enhanced if these renewable units in the system are optimally sized, located and configured. This piece of research provides a systematic scheme for computation of maximum penetration capacity (MPC) of SPVG in the distribution network. An investigative as well as optimization based algorithm is developed for estimating MPC at various locations in the system. In the proposed methodology, system voltage limits are considered as the constraint for MPC computation. MPC value obtained from meta heuristic method, namely, Particle Swarm Optimization (PSO) is compared with a deterministic scheme with same constraint. The proposed optimization algorithm clearly incorporates the ideal sequence of integration of SPVGs in the distributed scenario. Various interconnecting points of SPVGs in the test systems are affixed through a novel and analytically derived index value - Improved Power Stability Index (IPSI)- in deterministic scheme. This novel stability index is formulated by considering both active as well as reactive power support from SPVGs. The proposed methodology is also compared with other extant algorithms.

Predictive Distribution Modelling of Calamus andamanicus Kurz, an Endemic Rattan from Andaman and Nicobar Islands, India

Sreekumar, V.B.,Suganthasakthivel, R.,Sreejith, K.A.,Sanil, M.S. Institute of Forest Science 2016 Journal of Forest Science Vol.32 No.1

Calamus andamanicus Kurz is one of the commercially important solitary rattans endemic to Andaman and Nicobar islands. The habitat suitability modeling program, MaxEnt, was used to predict the potential ecological niches of this species, based on bioclimatic variables. The study revealed high potential distribution of C. andamanicus across both Andaman and Nicobar islands. Of the 33 spatially unique points, 21 points were recorded from South and North Andamans and 12 from Great Nicobar Islands. The islands like Little Andaman, North Sentinel, Little Nicobar, Tllangchong, Teressa were also predicted positive even though this rattan is not recorded from these islands. Mean diurnal range, higher precipitation in the wettest month of the year, annual precipitation and precipitation in the driest month are the main predictors of this species distribution.

Predictive Distribution Modelling of Calamus andamanicus Kurz, an Endemic Rattan from Andaman and Nicobar Islands, India

V.B. Sreekumar,R. Suganthasakthivel,K.A. Sreejith,M.S. Sanil 강원대학교 산림과학연구소 2016 Journal of Forest Science Vol.32 No.1

Calamus andamanicus Kurz is one of the commercially important solitary rattans endemic to Andaman and Nicobar islands. The habitat suitability modeling program, MaxEnt, was used to predict the potential ecological niches of this species, based on bioclimatic variables. The study revealed high potential distribution of C. andamanicus across both Andaman and Nicobar islands. Of the 33 spatially unique points, 21 points were recorded from South and North Andamans and 12 from Great Nicobar Islands. The islands like Little Andaman, North Sentinel, Little Nicobar, Tllangchong, Teressa were also predicted positive even though this rattan is not recorded from these islands. Mean diurnal range, higher precipitation in the wettest month of the year, annual precipitation and precipitation in the driest month are the main predictors of this species distribution.

Precursor synthesis and microwave processing of nickel ferrite nanoparticles

V.K.Sankaranarayanan,C.Sreekumar 한국물리학회 2003 Current Applied Physics Vol.3 No.2, 3

Nickel based ferrites have several applications in microwave components as dense polycrystalline compacts. In this study we haveprepared nickel ferrite nanoparticles by a self-ignition reaction directly from a citrate precursor. XRD patterns and FTIR spectraconrm the formation of single phase nickel ferrite. The sample couples readily with microwaves at ambient temperatures and theresidual carbon present in the self-ignited sample could be removed in a few minutes by microwave treatment. The samples,takes place.. 2002 Elsevier Science B.V. All rights reserved.

연료전지 자동차용 가솔린 연료 개질기의 개발 : 상용 ICI 촉매상에서 가솔린의 부분산화 개질반응

류종우,문동주,( K. Sreekumar ),이상득,안병성 한국공업화학회 2001 한국공업화학회 연구논문 초록집 Vol.2001 No.-

Catalytic production of hydrogen by partial oxidation (POX) reforming of gasoline is an attractive option for fuel-cell powered vehicles applications. As a part of the development of gasoline fuel processor systems, we investigated POX reforming of iso-octane with/without sulfur over a commercial ICI catalyst. It was found that the catalyst displayed prolonged stability in the POX reforming reaction of sulfur free iso-octane. However, the catalyst deactivated in the experiment of the sulfur containing iso-octane, indicating that the ICI catalyst is prone to be poisoned by sulfur impurities.

Effect of Metallic Interfacial Layers on the Properties of Diamond-Like Carbon Thin Films

Neeraj Dwivedi,Sushil Kumar,Sreekumar C,Saurabh Dayal,C. M. S. Rauthan,O.S. Panwar 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.2

Diamond like carbon (DLC) thin films with metallic interfacial layers of aluminum and nickel-chromium (Al and Ni-Cr) were grown using a low cost hybrid technique involving a resistive heating thermal evapo-rator and radio frequency plasma enhanced chemical vapor deposition techniques. Stress, hardness, elastic modulus, bonding, phase, and electrical conductivity of these films were investigated. Introduction of interfacial Al and Ni-Cr layers in DLC led to drastic improvement of its conductivity along with a signifi-cant reduction in residual stress but with some reduction of hardness and the elastic modulus. The struc-tural and surface properties of thin films were studied using X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy techniques.

Structural and Nano-Mechanical Properties of Nanostructured Diamond-Like Carbon Thin Films

Saurabh Dayal,Sushil Kumar,Neeraj Dwivedi,Sreekumar Chockalingam,C. M. S. Rauthan,O.S. Panwar 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.3

The effect of self bias on structural and nano-mechanical properties of nanostructured diamond-like carbon (ns-DLC) thin films is explored. These films are grown at different negative self biases ranging from −100 V to −200 V using radio frequency (13.56 MHz) plasma enhanced chemical vapor deposition technique. The generation of nanostructured morphology at room temperature in these films is confirmed by scanning electron microscopy, whereas change in microstructure produced by varying the self biases is confirmed by Raman analysis. These ns-DLC films exhibit very high hardness, which varied from 16 GPa to 31 GPa. With the help of load versus displacement curves, various other important nano-mechanical parameters such as elastic modulus, elastic recovery etc are also estimated. The nano-mechanical properties are further correlated with the Raman and SEM analyses. Owing to their versatile nano-mechanical properties, these ns-DLC films may find application as hard and protective coatings.

Budd-Chiari syndrome managed with percutaneous recanalization: Long-term outcome and comparison with medical therapy

Chinmay Bhimaji Kulkarni,Srikanth Moorthy,Sreekumar Karumathil Pullara,Nirmal Kumar Prabhu,Ramiah Rajesh Kannan,Puthukudiyil Kader Nazar 소화기인터벤션의학회 2019 International journal of gastrointestinal interven Vol.8 No.2

Background: To compare the outcomes in a group of patients with Budd-Chiari syndrome (BCS) managed by percutaneous recanalization with a group of patients who were managed by medical therapy alone.Methods: We retrieved the hospital records of 37 patients with BCS admitted to our facility between 2004 to 2017 and identified 24 patients (male:female = 10:14; mean age, 32.7 ± 12.5 years) who underwent percutaneous recanalization. Remaining thirteen patients (male:female = 3:10; mean age, 36.77 ± 14.71 years), were managed by medical therapy. Technical and clinical results, complications, and primary patency of percutane-ous recanalization were analyzed. Overall and symptom-free survival rates, the frequency of symptom recurrence, and the number of readmissions for recurrent symptoms were analyzed in both interventional treatment and medical therapy groups.Results: Technical success for recanalization of hepatic vein/inferior venecava by angioplasty ± stenting was achieved in 22 patients (22/24, 91.7%). Clinical success was achieved in 19 patients (19/24, 79.2%). Overall survival for patients who underwent percutaneous recanalization at 1 year and five years was 87.0% and 87.0% and for patients with medical therapy was 90.1% and 45.5%, respectively (P = 0.710). Symptom-free survival for patients who underwent percutaneous recanalization at 1 year and five year was 93.3% and 81.7% and for patients with medical therapy was 26.0% and 0%, respectively (P < 0.001). In the intervention group, 4 patients (4/24, 16.7%) were admitted for recurrent symptoms (median number of read-missions 1, range: 1–2) whereas in medically managed patients 9 patients (9/13, 69.2%) were readmitted (median number of readmissions, 2; range, 1–5) (P = 0.003).Conclusion: There was no statistically significant difference in overall survival of patients managed with percutaneous recanalization and medical therapy. Percutaneous recanalization had definite benefit in terms of fewer recurrent symptoms and hospital admissions, hence should be performed whenever technically feasible.

Endovascular Treatment of Aneurysm of Splenic Artery Arising from Splenomesentric Trunk Using Stent Graft

Chinmay Bhimaji Kulkarni,Srikanth Moorthy,Sreekumar Karumathil Pullara,Rajesh Ramaih Kannan 대한영상의학회 2013 Korean Journal of Radiology Vol.14 No.6

We report a rare case of aneurysm of splenic artery arising anomalously from the superior mesenteric artery (SMA). The aneurysm was treated successfully by coil embolization of the splenic artery distal to aneurysm and then deploying a stent graft in the SMA. A combination of stent graft and coil embolization for the treatment of aberrant splenic artery aneurysm has been reported only once. We describe the imaging findings and the endovascular procedure in this patient.

Budd-Chiari syndrome managed with percutaneous recanalization: Long-term outcome and comparison with medical therapy

Chinmay Bhimaji Kulkarni,Srikanth Moorthy,Sreekumar Karumathil Pullara,Nirmal Kumar Prabhu,Ramiah Rajesh Kannan,Puthukudiyil Kader Nazar 소화기인터벤션의학회 2019 Gastrointestinal Intervention Vol.8 No.2

Background: To compare the outcomes in a group of patients with Budd-Chiari syndrome (BCS) managed by percutaneous recanalization with a group of patients who were managed by medical therapy alone.Methods: We retrieved the hospital records of 37 patients with BCS admitted to our facility between 2004 to 2017 and identified 24 patients (male:female = 10:14; mean age, 32.7 ± 12.5 years) who underwent percutaneous recanalization. Remaining thirteen patients (male:female = 3:10; mean age, 36.77 ± 14.71 years), were managed by medical therapy. Technical and clinical results, complications, and primary patency of percutane-ous recanalization were analyzed. Overall and symptom-free survival rates, the frequency of symptom recurrence, and the number of readmissions for recurrent symptoms were analyzed in both interventional treatment and medical therapy groups.Results: Technical success for recanalization of hepatic vein/inferior venecava by angioplasty ± stenting was achieved in 22 patients (22/24, 91.7%). Clinical success was achieved in 19 patients (19/24, 79.2%). Overall survival for patients who underwent percutaneous recanalization at 1 year and five years was 87.0% and 87.0% and for patients with medical therapy was 90.1% and 45.5%, respectively (P = 0.710). Symptom-free survival for patients who underwent percutaneous recanalization at 1 year and five year was 93.3% and 81.7% and for patients with medical therapy was 26.0% and 0%, respectively (P < 0.001). In the intervention group, 4 patients (4/24, 16.7%) were admitted for recurrent symptoms (median number of read-missions 1, range: 1–2) whereas in medically managed patients 9 patients (9/13, 69.2%) were readmitted (median number of readmissions, 2; range, 1–5) (P = 0.003).Conclusion: There was no statistically significant difference in overall survival of patients managed with percutaneous recanalization and medical therapy. Percutaneous recanalization had definite benefit in terms of fewer recurrent symptoms and hospital admissions, hence should be performed whenever technically feasible.