High Power, Continuous-wave Supercontinuum Generation in Highly Nonlinear Fibers Pumped with High Order, Cascaded Raman Fiber Amplifiers

A novel method for efficient generation of high power, equalized continuous-wave supercontinuum source in an all conventional silica fiber architecture is demonstrated. Highly nonlinear fiber (HNLF) is pumped in its anomalous dispersion region using a novel, high power, L-band laser. The L-band laser encompasses a 6th order cascaded Raman amplifier which is pumped with a high power Ytterbium doped fiber laser and amplifies a low-power, tunable L-band seed source. The supercontinuum generated 35W of power with ~40% efficiency. The Supercontinuum spectrum was measured to have a high degree of flatness of better than 5 dB over 400 nm of bandwidth (1.3 - 1.7 micron, limited by spectrum analyzer range) and a power spectral density in this region of >50 mW/nm. The extent of the SC spectrum is estimated to be upto 2 micronComment: 6 pages, 5 figure

High Power, Tunable, Continuous-Wave Fiber Lasers in the L-band using Cascaded Raman Amplifiers

We demonstrate a high power, all-fiber, tunable laser source that can operate in the L-band region. A low power, tunable input laser is amplified with a recently proposed, high efficiency, 6th order cascaded Raman amplifier. The proposed system is scalable and overcomes the limitations of Erbium and Erbium-Ytterbium co-doped fiber lasers for power scaling. A tunable Erbium-Ytterbium co-doped fiber ring laser generating ~0.5W of power and tunable in the 1560-1590 nm wavelength range is utilized as the seed source. The output from the seed laser is amplified to ~24 W using 6th order cascaded Raman amplification. A high power Yb laser operating at 1117nm is used as the pump laser for driving the Raman conversions. The operating wavelength of the demonstrated laser in the eye-safe, atmospherically transparent region enables high power free-space applications. In addition, this source enables other interesting applications such as high power supercontinuum generation with conventional silica fibers.Comment: 6 pages, 5 figure

High power, fixed and tunable wavelength, Grating-free Cascaded Raman fiber Lasers

Cascaded Raman lasers enable high powers at various wavelength bands inaccessible with conventional rare-earth doped lasers. The input and output wavelengths of conventional implementations are fixed by the constituent fiber gratings necessary for cascaded Raman conversion. We demonstrate here, a simple architecture for high power, fixed and wavelength tunable, grating-free, cascaded Raman conversion between different wavelength bands. The architecture is based on the recently proposed distributed feedback Raman lasers. Here, we implement a module which converts the Ytterbium band to the eye-safe 1.5micron region. We demonstrate pump-limited output powers of over 30W in fixed and continuously wavelength tunable configurations.Comment: 6 pages, 5 figures, final versio

Investigation of bioclimatic design features in vernacular architecture of Northeast India: Case studies of Assam-type houses and stilt houses (Chang Ghar) in Assam, India

Bioclimatic design features in the buildings are based on surrounding geography and climate to create comfortable and healthy spaces. These features are observed in the vernacular architecture styles across the regions of India. Various bioclimatic design strategies are also observed in Northeast India; however, they are less focused when compared to other regions of India. Therefore, this paper attempts to investigate bioclimatic features in the vernacular architecture of Northeast India, wherein it focuses on two typologies, i.e., Assam-type house and Stilt houses (Chang Ghar). A qualitative analysis based on the site surveys was done to identify bioclimatic features used in the two selected typologies. The parameters selected to investigate bioclimatic features include the type of construction materials and methods used; the spatial arrangement of spaces; orientation and layout of the building; wall thickness; nearby open spaces; vegetation and water bodies; openings and ventilation; window to wall ratio; plinth height; design and material of shading devices; structure, height, and material of ceiling, any other special features. Overall, the results indicated that Assam-type houses and stilt houses are highly responsive to the local climate, utilizes locally available materials (bamboo, wood, and mud), and reflects the living style, customs, and socio-economic conditions. The outcome of this qualitative study was the identification of multiple bioclimatic features observed in both typologies. The recommendations from this study can act as a reference for designing buildings that shall promote sustainable built environments as per United Nations Sustainable Development Goal number 11 (Sustainable cities and communities)

Predicting prognosis in large cohort of decompensated cirrhosis of liver (DCLD)- a machine learning (ML) approach

Background and aims: Onset of decompensation in cirrhosis is associated with poor outcome. The current clinico-biochemical tools have limited accuracy in predicting outcomes reliably. Identifying the predictors with precision model on the big data using artificial intelligence may improve predictability. We aimed to develop a machine learning (ML) based prognostic model for predicting 90 day survival in patients of cirrhosis presenting with decompensation. Method: We analysed electronic medical records retrospectively of hospitalised cirrhosis patients at the ILBS, with a complete 90-day follow-up. Clinical data, laboratory parameters and organ involvement were serially noted. AI-modelling was done after appropriate mining, feature engineering, splitted randomly into train and testsets (20:80). The class imbalance problem was handled by random over-sampling technique, to make balanced 50:50 ratios. After 10- fold cross validation, 3 repetitions and grid search for optimal hyper parameters, the XGB-CV model was chosen. AUC was the primary selection criteria and confusion matrix was used to compare AUCs between AI-models and existing indices; CTP and MELD-score. Results: Total of 6326 patients [mean age 48.2 ± 11.5 years, 84% male, Mean CTP 10.4 ± 2.2 and MELD Na-30.4 ± 11.9, alcohol 49.4%] were included. Ninety day mortality was 29.2%. Acute insult was identified in 80% cases; of which extra-hepatic 49%, hepatic 46% and unknown 5% cases respectively. The XGB-CV model had the best accuracy for prediction of 90 days event in the train set 0.90 (0.90–0.93), validation set 0.80 (0.79–0.81) and for overall dataset 0.80 (0.79– 0.81). The AUC of the XGB-CV model was better than CTP and MELD Na-score by 16% and 15% respectively. The prediction model considered 43 variables; 18 of which predicted the outcome, and 10 maximum contributors are shown in concordance classifier. The most contributors to poor outcome included, index presentation as HE, diagnosis of AD/ACLF/ESLD, PT-INR, serum creatinine, total bilirubin, acute insult etiology, prior decompensation, acute hepatic or extrahepatic insult, leukocyte count and present duration of illness. In the Decision Tree Model, the presence of HE, PT-INR and syndromic diagnosis of AD or ACLF/ESLD was able to stratify the patients into low (22%), intermediate (23–46%) and high risk (\u3e75%) of mortality at 90 days. Conclusion: The AI based current model developed using a large data base of CLD patients presenting with decompensation immensely adds to the current indices of liver disease severity and can stratify patients at admission. Simple ML algorithms using HE and INR besides syndromic presentation, could help treatment decisions and prognostication

Unsupervised Extractive News Articles Summarization leveraging Statistical, Topic-Modelling and Graph-based Approaches

Due to the presence of large amounts of data and its exponential level generation, the manual approach of summarization takes more time, is biased, and needs linguistic professional experts. To avoid these substantial issues or to generate a succinct summary report, automatic text summarization is very much important. Three different approaches namely the statistical approach such as Term Frequency Inverse Document Frequency(TF-IDF), the topic modeling approach such as Latent Semantic Analysis (LSA), and graph-based approaches such as TextRank were applied to generate a concise summary for the benchmark the British Broadcasting Corporation (BBC) news articles summarization dataset. The domain-specific implementations of each approach in the five domains of the dataset and domain-agnostic prospects were explored in the paper while drawing various insights. The generated summaries were evaluated using the Recall-Oriented Understudy for Gisting Evaluation (ROUGE) framework, leveraging precision, recall, and f-measure metrics. The approaches were not only able to achieve a commendable ROUGE score but also outperform the previous works on the datase

Investigation of bioclimatic design features in vernacular architecture of Northeast India: Case studies of Assam-type houses and stilt houses (Chang Ghar) in Assam, India

664-673Bioclimatic design features in the buildings are based on surrounding geography and climate to create comfortable and healthy spaces. These features are observed in the vernacular architecture styles across the regions of India. Various bioclimatic design strategies are also observed in Northeast India; however, they are less focused when compared to other regions of India. Therefore, this paper attempts to investigate bioclimatic features in the vernacular architecture of Northeast India, wherein it focuses on two typologies, i.e., Assam-type house and Stilt houses (Chang Ghar). A qualitative analysis based on the site surveys was done to identify bioclimatic features used in the two selected typologies. The parameters selected to investigate bioclimatic features include the type of construction materials and methods used; the spatial arrangement of spaces; orientation and layout of the building; wall thickness; nearby open spaces; vegetation and water bodies; openings and ventilation; window to wall ratio; plinth height; design and material of shading devices; structure, height, and material of ceiling, any other special features. Overall, the results indicated that Assam-type houses and stilt houses are highly responsive to the local climate, utilizes locally available materials (bamboo, wood, and mud), and reflects the living style, customs, and socio-economic conditions. The outcome of this qualitative study was the identification of multiple bioclimatic features observed in both typologies. The recommendations from this study can act as a reference for designing buildings that shall promote sustainable built environments as per United Nations Sustainable Development Goal number 11 (Sustainable cities and communities)