Coherent diffraction surface imaging in reflection geometry

Marathe, Shashidhara,Kim, S. S.,Kim, S. N.,Kim, Chan,Kang, H. C.,Nickles, P. V.,Noh, D. Y. The Optical Society 2010 Optics express Vol.18 No.7

<P>We present a reflection based coherent diffraction imaging method which can be used to reconstruct a non periodic surface image from a diffraction amplitude measured in reflection geometry. Using a He-Ne laser, we demonstrated that a surface image can be reconstructed solely from the reflected intensity from a surface without relying on any prior knowledge of the sample object or the object support. The reconstructed phase image of the exit wave is particularly interesting since it can be used to obtain quantitative information of the surface depth profile or the phase change during the reflection process. We believe that this work will broaden the application areas of coherent diffraction imaging techniques using light sources with limited penetration depth.</P>

Species and functional group composition of ant communities across an elevational gradient in the Eastern Himalaya

Marathe Aniruddha,Shanker Kartik,Krishnaswamy Jagdish,Priyadarsanan Dharma Rajan 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.4

Elevational gradients in mountains show rapid changes in environmental conditions across a small geographic extent. This results in habitat specialization in animal communities which results in changes in species composition across space. We explore changes in species and functional group composition of ants using the first ever data on the distribution of ants across an elevational gradient in the Eastern Himalaya. Ants were sampled from 600 to 2400 m elevations at 200 m intervals using Winklers and pitfall traps. The sampling yielded 166 species of ants from 10,560 individuals, which were then classified into functional groups. We used redundancy analysis to test the effects of environmental factors (temperature, leaflitter volume, understory vegetation) and spatial predictors on species as well as functional group composition of communities at different elevations. Our results show that species diversity within all functional groups decreases towards higher elevations. The func tional group composition of ant communities shows a gradient from high evenness at low elevations to being dominated by opportunist species at higher elevations. Redundancy analyses shows that most of the variation in species as well as functional group composition is driven by spatially structured environmental variation. This is most likely due to the high correlation between temperature and elevation. In summary, the changes in species as well as functional group composition are likely driven by a gradient in climate across the elevation gradient.

Neem acetylated polyester polyol-Renewable source based smart PU coatings containing quinoline (corrosion inhibitor) encapsulated polyurea microcapsules for enhance anticorrosive property

Marathe, R.,Tatiya, P.,Chaudhari, A.,Lee, J.,Mahulikar, P.,Sohn, D.,Gite, V. Elsevier 2015 INDUSTRIAL CROPS AND PRODUCTS Vol.77 No.-

In this article, we represent preparation of renewable source based smart polyurethane coatings reacting polyols prepared by acetylation of neem oil with different diisocyanates in presence of encapsulated corrosion inhibitor. The structures of polyols were confirmed by Fourier transfer infra-red and nuclear magnetic resonance spectroscopic techniques. The prepared polyols were used to form polyurethane coatings by treating with diisocyanates such as methylene phenyl, dicyclohexylmethane, and isophorone diisocyanates. Further, conversion of polyurethane to smart coatings was carried by incorporation of encapsulated form of quinoline as a corrosion inhibitor. Coatings were characterized for their thermal stability and physico-chemical properties by suitable sophisticated techniques. Anticorrosive properties of the smart coatings were studied by exposing them to corrosive medias like 0.5M HCl and 3.5% NaCl solutions. Incorporation of encapsulated corrosion inhibitor into the neem oil based smart PU coatings shown enhanced anticorrosive property. Finding of this study also shown encapsulated form of commercial corrosion inhibitor can be extended for other PU coatings.

Long-Term Functional Outcomes of Endoscopic Decompression with Destandau Technique for Lumbar Canal Stenosis

Gupta Saransh,Marathe Nandan,Chhabra Harvinder Singh,Destandau Jean 대한척추외과학회 2021 Asian Spine Journal Vol.15 No.4

Study Design: Retrospective study of patients with lumbar canal stenosis (LCS) operated using endoscopic unilateral laminotomy with bilateral decompression (ULBD).Purpose: This study aimed to provide a detailed description of the technique of endoscopic decompression in LCS along with a description of the surgical anatomy and its advantages. We also discuss the clinical outcomes in patients operated using this technique.Overview of Literature: In 1999, the results with the use of microscopic ULBD were published. Microscopic/microendoscopic decompression using tubular retractor system showed good to excellent results in studies that compared such techniques with midline decompression. The first description of the use of endoscope in spine surgery was in 1988 when it was used for discectomy. With advancements and familiarity with the techniques, full endoscopic surgery has found application in LCS treatment.Methods: The clinical records of 953 patients who were operated between 1998 and 2008 were analyzed in 2018. Along with patient characteristics, information about return to daily activities, complication rates, and functional outcomes using Prolo score was assessed.Results: L4–L5 was the most common level for which surgery was performed. Two-level decompression was performed in 116 patients; 89.5% patients were able to return to their daily activities after 2 weeks. Functional outcomes as per the Prolo score were reported by patients as excellent, good, and poor in 89.85%, 1.59%, and 8.55%, respectively. Repeat surgery was required at same level in 16 patients and at a different level in 21 patients. Total 605 patients (63.49%) were symptom-free during the 70-month followup, while 344 complained of residual back pain, and four complained of persistent leg pain.Conclusions: ULBD using the Endospine system achieves adequate decompression in most cases and is a good alternative to open laminectomy, with the advantage of avoiding damage to the structural integrity of the spine and preserving soft tissue attachments.

Comparison of Various Methods to Mitigate the Flicker Level of DFIG in Considering the Effect of Grid Conditions

Yun-Seong Kim,Aditya Marathe,Dong-Jun Won 전력전자학회 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.4

The short circuit ratio (SCR) of a given grid is able to show the stability of the system in the case of unwanted elements, such as wind turbulence. This paper presents the simulation of a model of the doubly fed induction generator in the simulation software PSCAD/EMTDC. This model has been used to study flicker during continuous operation and the effect of SCR and grid impedance angle on flicker emission. Simulation results show that compensation of the stator reactive power is an effective method to considerably reduce the flicker levels, irrespective of the grid conditions.

Comparison of Various Methods to Mitigate the Flicker Level of DFIG in Considering the Effect of Grid Conditions

Kim, Yun-Seong,Marathe, Aditya,Won, Dong-Jun The Korean Institute of Power Electronics 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.4

The short circuit ratio (SCR) of a given grid is able to show the stability of the system in the case of unwanted elements, such as wind turbulence. This paper presents the simulation of a model of the doubly fed induction generator in the simulation software PSCAD/EMTDC. This model has been used to study flicker during continuous operation and the effect of SCR and grid impedance angle on flicker emission. Simulation results show that compensation of the stator reactive power is an effective method to considerably reduce the flicker levels, irrespective of the grid conditions.

Role of Additional Coronal Magnetic Resonance Imaging in Decompression and Reconstruction with or without Segment Salvage in Thoracic Spine Tuberculosis

Sudhir Srivastava,Nandan Marathe,Sunil Bhosale,Prajakta Bhide,Shaligram Purohit,Chetan Shende,Balgovind Raja 대한척추외과학회 2019 Asian Spine Journal Vol.13 No.6

Study Design: Retrospective and observational study. Purpose: The present study aimed to develop guidelines for segment salvage or sacrifice based on the amount and status of the remnant portion of the vertebra as assessed by coronal magnetic resonance imaging (MRI) in addition to sagittal and axial images in thoracic spine tuberculosis (TB). Overview of Literature: Indications for surgery have not changed significantly since the ‘middle path regimen’ was proposed by Tuli. Goals of modern surgical management of spinal TB include debridement of diseased vertebrae, spinal cord decompression, deformity correction, and spine stabilization. However, the extent of decompression has not been defined previously. Too less decompression will lead to compromised neurological recovery, whereas large extent of decompression is associated with increased surgical morbidity and longer segment to reconstruct. Methods: Sixty-five patients with thoracic spine TB were divided into two groups (segment salvage/sacrifice) based on the thickness of the subchondral bone and endplate morphology of the vertebra as seen on MRI. The operative procedure in the form of instrumentation with Hartshill loop rectangle and sublaminar wire using the simultaneous anterior posterior approach in lateral position (versatile approach) was performed. The patients were analyzed for postoperative fusion, improvement in kyphosis angle, and followed up for development of complications. Results: This method of deciding the level of fixation and segment salvage based on coronal MRI in addition to the sagittal and axial images provided good result in 64 of 65 patients, except for one patient in the segment sacrifice group who had graft buckling and resultant kyphosis. Conclusions: For segment salvage, having a clear three-dimensional idea about the viable remnant bone is important. Viable salvaged segment reduces the morbidity of the procedure, length of the construct, and unnecessary debridement without compromising on the neural recovery and fusion rate. Hence, additional cone down coronal cuts must be required when MRI is suggestive for spinal TB because it will help in the decision making.

Radiographic Analysis of the Sagittal Alignment of Spine and Pelvis in Asymptomatic Indian Population

Sangondimath Gururaj,Mallepally Abhinandan Reddy,Marathe Nandan,Salimath Suman,Chhabra Havinder Singh 대한척추외과학회 2022 Asian Spine Journal Vol.16 No.1

Study Design: This is a descriptive observational study.Purpose: The objective of this study is to analyze and document the sagittal alignment of the spine and pelvis in normal Indian adult volunteers and compare these parameters with the study population of other races and ethnicities.Overview of Literature: Given the importance of the spinopelvic parameters, there is a need to describe the parameters differentially in relation to the ethnicity of the studied individual. Very few reports have defined the normal physiological value. Ethnic differences are a significant factor not only when describing the anthropometric data but also when applying the findings to a different ethnic group. We have compared these values with other races and ethnicities so that we can know whether the principles of spinal fixation can be applied globally.Methods: In total, 100 participants were studied by using their anteroposterior and lateral radiographic images of whole of pelvic and spinal area. Additionally, various spinal and pelvic parameters were also measured. Subsequently, the outcomes were analyzed with respect to age, sex, and body mass index (BMI). The correlation between different parameters and differences in these parameters between Indians and other races/ethnicities along with population groups were also analyzed. Results: There was a significant increase in thoracic kyphosis (TK) from T1–T12 and T4–T12 with increasing age. Lumbar lordosis (LL), sacral translation (sagittal vertical axis), and pelvic tilt were significantly higher among females. Additionally, sacral slope (SS), pelvic incidence, C7 sagittal offset, and T9 sagittal offset were also higher in females. TK (T4–T12 and T1–T12), LL, SS, and pelvic incidence showed a significant correlation with BMI. As compared to European population, TK, segmental LL, and sacral translation were found to be significantly lesser in Indian population.Conclusions: There is a statistically significant difference between Indians and other races/ethnicities and population groups with respect to TK, LL, and sacral translation. The values obtained can be considered as the physiological normal values for Indian population. Importantly, these values can serve as the reference values for future studies.

Coherent hard x-ray diffractive imaging of nonisolated objects confined by an aperture

Kim, Sunam,Kim, Chan,Lee, Suyong,Marathe, Shashidhara,Noh, D. Y.,Kang, H. C.,Kim, S. S.,Sandy, A.,Narayanan, S. American Physical Society 2010 Physical review. B, Condensed matter and materials Vol.81 No.16

Computing turbulent far-wake development behind a wind turbine with and without swirl

Yingying Hu,Siva Parameswaran,Jiannan Tan,Suranga Dharmarathne,Neha Marathe,Zixi Chen,Ronald Grife,Andrew Swift 한국풍공학회 2012 Wind and Structures, An International Journal (WAS Vol.15 No.1

Modeling swirling wakes is of considerable interest to wind farm designers. The present work is an attempt to develop a computational tool to understand free, far-wake development behind a single rotating wind turbine. Besides the standard momentum and continuity equations from the boundary layer theory in two dimensions, an additional equation for the conservation of angular momentum is introduced to study axisymmetric swirl effects on wake growth. Turbulence is simulated with two options: the standard k-ε model and the Reynolds Stress transport model. A finite volume method is used to discretize the governing equations for mean flow and turbulence quantities. A marching algorithm of expanding grids is employed to enclose the growing far-wake and to solve the equations implicitly at every axial step. Axisymmetric far-wakes with/without swirl are studied at different Reynolds numbers and swirl numbers. Wake characteristics such as wake width, half radius, velocity profiles and pressure profiles are computed. Compared with the results obtained under similar flow conditions using the computational software, FLUENT, this far-wake model shows simplicity with acceptable accuracy, covering large wake regions in far-wake study.