401 research outputs found
Low loss transmission in negative curvature optical fibers with elliptical capillary tubes
No full textRegular and nested negative curvature optical fibers with elliptical capillary tubes have been proposed in this paper for ultralow loss guidance at the telecommunication wavelength. Finite element modeling shows that these fibers can have lower loss compared to their counterparts with circular tubes. These hollow core fibers with low loss and large bandwidth can have huge potential applications in data transmission, sensing, high power delivery, and serve as an ideal platform for the study of a wide variety of nonlinear optical effects
A Novel Technique Based on Deep Learning and a Synthetic Target Database for Classification of Urban Areas in PolSAR Data
No full textThe classification of urban areas in polarimetric synthetic aperture radar (PolSAR) data is a challenging task. Moreover, urban structures oriented away from the radar line of sight pose an additional complexity in the classification process. The characterization of such areas is important for disaster relief and urban sprawl monitoring applications. In this paper, a novel technique based on deep learning is proposed, which leverages a synthetic target database for data augmentation. The PolSAR dataset is rotated by uniform steps and collated to form a reference database. A stacked autoencoder network is used to transform the information in the augmented dataset into a compact representation. This significantly improves the generalization capabilities of the network. Finally, the classification is performed by a multilayer perceptron network. The modular architecture allows for easy optimization of the hyperparameters. The synthetic target database is created and the classification performance is evaluated on an L-band airborne UAVSAR dataset and L-band space-borne ALOS-2 dataset acquired over San Francisco, USA. The proposed technique shows an overall accuracy of 91.3%. An improvement over state-of-the-art techniques is achieved, especially in urban areas rotated away from the radar line of sight
Reading Slant During Covid-19: A Contrarian List
No full textToday's academia is obsessed about writing and speaking gobbledygook. At least most of the time. It has little time in sitting still and actually reading fiction, poetry and say, Wittgenstein. One pretends to say fancy things about these authors but one does not actually read books anymore. COVID 19 Lockdown prompted this author to answer queries from students and peers about a reading list. So prepare a wide ranging list he did which covers everything from the version of Mahabharata one ought to read to novels on celibacy. But then he chose to publish at Prabuddha Bharata over all other platforms because the Ramakrishna Mission has the finances to keep this list alive 200 years hence. This was written during COVID 19 Lockdown in India at the end of April, 2020. Nirad C Chaudhuri insisted on making a good bibliography in his magnum opus. This author follows Nirad C Chaudhuri in quietly speaking about how Harold Bloom plagiarised the Late Professor John Senior's reading list. The list also comments on Romanticism and the art of writing itself. The list on Hinduism is truly contrarian. One hopes that this list survives when GoodReads and other Listopias are no longer. Today's academia is obsessed about writing and speaking gobbledygook. At least most of the time. It has little time in sitting still and actually reading fiction, poetry and say, Wittgenstein. One pretends to say fancy things about these authors but one does not actually read books anymore. COVID 19 Lockdown prompted this author to answer queries from students and peers about a reading list. So prepare a wide ranging list he did which covers everything from the version of Mahabharata one ought to read to novels on celibacy. But then he chose to publish at Prabuddha Bharata over all other platforms because the Ramakrishna Mission has the finances to keep this list alive 200 years hence. This was written during COVID 19 Lockdown in India at the end of April, 2020. Nirad C Chaudhuri insisted on making a good bibliography in his magnum opus. This author follows Nirad C Chaudhuri in quietly speaking about how Harold Bloom plagiarised the Late Professor John Senior's reading list. The list also comments on Romanticism and the art of writing itself. The list on Hinduism is truly contrarian. One hopes that this list survives when GoodReads and other Listopias are no longer. These COVID 19 days, while the First world is mooning over syllabi for their kids and third and fourth world folks like me are tackling Umphan; I chose to prepare a new kind of syllabus. A syllabus which is not merely a list. In these days of incessant and meaningless webinars which my students can only spread memes about and only the poor and doctors will actually travel to white nations which are killing their own; here's a list which ends with Hindu classics which are contrarian. Nirad C Chaudhuri, a much maligned man in India and a forgotten polyglot in white privileged academia said we must first prepare a bibliography. So, Figure it out. I used some of the Hindu resources on recognition mentioned here and tried to work on Stephen King; a privileged white tenure track person from Trumpland just snowballed me. Now, this list is syllabi and also just a list of a bunch of books to read during Lockdowns which will be more common in the future because COVID 19, as Dr Fauci tells us; is here to stay. Even if one COVID 19 person is there; then along with Ebola, my white privileged tenure track fiends; off you go to gagaland. We in India already know these diseases. Go figure it out
Crystalline silicon optical fibers with low optical loss
No full textPolycrystalline silicon core optical fibers have been fabricated by modified thermal annealing of amorphous silicon chemically deposited at high pressure. The resulting fibers have small-diameter cores, a geometry advantageous for optical guidance. Moreover, the combination of chemical deposition and annealing avoids difficulties associated with undesired transfer of oxygen impurities to the silicon core from the molten cladding during the drawing process. The high aspect ratio of the amorphous silicon core and the presence of the silica cladding surrounding make the design rules for annealing to optimize their polycrystalline structure different from those of conventional amorphous silicon films. We find that optimization of the annealing allows for an increase in the polycrystalline grain size and decrease in the defects in the silicon core. A low optical loss of less than 1 dB/cm at a wavelength of 2.2 µm is thus realized, much lower than that reported for small core size (<10 µm) crystalline silicon fibers and comparable to the loss in many planar semiconductor waveguides. This loss is just below the threshold of 1 dB/cm often considered necessary for many photonic and optoelectronic applications at near to mid-infrared wavelengths in areas such as nonlinear photonics, lasers, and in-fiber photodetectors. Further reduction in optical losses as deposition and annealing techniques are improved can be anticipated
Exploring the effect of the core boundary curvature in hollow antiresonant fibers
No full textThrough numerical simulations, we systematically study the leakage loss properties of a simplified novel hollow antiresonant fiber in which the core is surrounded by semi-elliptical elements. These studies lead to new insight into the effect of the curvature of the core boundary in antiresonant fibers. We observe in particular that in our design, there exists an optimum curvature of the elements—which we quantify simply through the aspect ratio of the ellipses—for which the fiber’s leakage loss is minimized. Furthermore, it is shown that elliptical elements can lead to orders of magnitude loss reduction as compared with similar fibers with circular ones
AMERICAN GOTHIC MAINSTREAM FICTION
No full textThis is my (Subhasis Chattopadhyay's) draft of PhD pre-submission. Dr. Scriver has (had) put it up online in her blog and I found it today, that is 1:06 pm, 28th May, 2017. I am grateful to her since intellectual ideas can otherwise be hijacked. She has done a wonderful editorial job. I want to make it clear that the author of the blog post is Dr. Scriver and not I. But in the Add Contributor here I cannot insert her name as the author so I have out her as an editor which is incorrect. Her blog-post though is in the public domain. Please see http://prairiemary.blogspot.in/2013/03/it-was-all-very-unexpected-and.htm
Data for "Exploring the effect of the core boundary curvature in hollow antiresonant fibers"
No full textData used for figures in the paper:
Van Putten, Lieke et al (2016) Exploring the Effect of the Core Boundary Curvature in Hollow Antiresonant Fibers. Photonic Technology Letters.
Excel data files
Figure 3a and 3b are the leakage loss and ratio of power in the cladding for each structure. Figure 4 contains the data used to compare the loss using air-filled and glass-filled structures. Figure 6 is the data that shows the ratio of the contribution to the leakage loss for the different boundary areas on the fiber (figure6b) as well as the corresponding leakage loss at the tested frequency (figure6a).</span
Reading Slant During Covid-19: A Contrarian List
No full textToday's academia is obsessed about writing and speaking gobbledygook. At least most of the time. It has little time in sitting still and actually reading fiction, poetry and say, Wittgenstein. One pretends to say fancy things about these authors but one does not actually read books anymore. COVID 19 Lockdown prompted this author to answer queries from students and peers about a reading list. So prepare a wide ranging list he did which covers everything from the version of Mahabharata one ought to read to novels on celibacy. But then he chose to publish at Prabuddha Bharata over all other platforms because the Ramakrishna Mission has the finances to keep this list alive 200 years hence. This was written during COVID 19 Lockdown in India at the end of April, 2020. Nirad C Chaudhuri insisted on making a good bibliography in his magnum opus. This author follows Nirad C Chaudhuri in quietly speaking about how Harold Bloom plagiarised the Late Professor John Senior's reading list. The list also comments on Romanticism and the art of writing itself. The list on Hinduism is truly contrarian. One hopes that this list survives when GoodReads and other Listopias are no longer. Today's academia is obsessed about writing and speaking gobbledygook. At least most of the time. It has little time in sitting still and actually reading fiction, poetry and say, Wittgenstein. One pretends to say fancy things about these authors but one does not actually read books anymore. COVID 19 Lockdown prompted this author to answer queries from students and peers about a reading list. So prepare a wide ranging list he did which covers everything from the version of Mahabharata one ought to read to novels on celibacy. But then he chose to publish at Prabuddha Bharata over all other platforms because the Ramakrishna Mission has the finances to keep this list alive 200 years hence. This was written during COVID 19 Lockdown in India at the end of April, 2020. Nirad C Chaudhuri insisted on making a good bibliography in his magnum opus. This author follows Nirad C Chaudhuri in quietly speaking about how Harold Bloom plagiarised the Late Professor John Senior's reading list. The list also comments on Romanticism and the art of writing itself. The list on Hinduism is truly contrarian. One hopes that this list survives when GoodReads and other Listopias are no longer. These COVID 19 days, while the First world is mooning over syllabi for their kids and third and fourth world folks like me are tackling Umphan; I chose to prepare a new kind of syllabus. A syllabus which is not merely a list. In these days of incessant and meaningless webinars which my students can only spread memes about and only the poor and doctors will actually travel to white nations which are killing their own; here's a list which ends with Hindu classics which are contrarian. Nirad C Chaudhuri, a much maligned man in India and a forgotten polyglot in white privileged academia said we must first prepare a bibliography. So, Figure it out. I used some of the Hindu resources on recognition mentioned here and tried to work on Stephen King; a privileged white tenure track person from Trumpland just snowballed me. Now, this list is syllabi and also just a list of a bunch of books to read during Lockdowns which will be more common in the future because COVID 19, as Dr Fauci tells us; is here to stay. Even if one COVID 19 person is there; then along with Ebola, my white privileged tenure track fiends; off you go to gagaland. We in India already know these diseases. Go figure it out
MAR-DTN: Metal Artifact Reduction Using Domain Transformation Network for Radiotherapy Planning
No full textFor the planning of radiotherapy treatments for head and neck cancers, Computed Tomography (CT) scans of the patients are typically employed. However, in patients with head and neck cancer, the quality of standard CT scans generated using kilo-Voltage (kVCT) tube potentials is severely degraded by streak artifacts occurring in the presence of metallic implants such as dental fillings. Some radiotherapy devices offer the possibility of acquiring Mega-Voltage CT (MVCT) for daily patient setup verification, due to the higher energy of X-rays used, MVCT scans are almost entirely free from artifacts making them more suitable for radiotherapy treatment planning. In this study, we leverage the advantages of kVCT scans with those of MVCT scans (artifact-free). We propose a deep learning-based approach capable of generating artifact-free MVCT images from acquired kVCT images. The outcome offers the benefits of artifact-free MVCT images with enhanced soft tissue contrast, harnessing valuable information obtained through kVCT technology for precise therapy calibration. Our proposed method employs UNet-inspired model, and is compared with adversarial learning and transformer networks. This first and unique approach achieves remarkable success, with PSNR of 30.02dB across the entire patient volume and 27.47dB in artifact-affected regions exclusively. It is worth noting that the PSNR calculation excludes the background, concentrating solely on the region of interest
Location Matters: Harnessing Spatial Information to Enhance the Segmentation of the Inferior Alveolar Canal in CBCTs
No full textThe segmentation of the Inferior Alveolar Canal (IAC) plays a central role in maxillofacial surgery, drawing significant attention in the current research. Because of their outstanding results, deep learning methods are widely adopted in the segmentation of 3D medical volumes, including the IAC in Cone Beam Computed Tomography (CBCT) data. One of the main challenges when segmenting large volumes, including those obtained through CBCT scans, arises from the use of patch-based techniques, mandatory to fit memory constraints. Such training approaches compromise neural network performance due to a reduction in the global contextual information. Performance degradation is prominently evident when the target objects are small with respect to the background, as it happens with the inferior alveolar nerve that develops across the mandible, but involves only a few voxels of the entire scan. In order to target this issue and push state-of-the-art performance in the segmentation of the IAC, we propose an innovative approach that exploits spatial information of extracted patches and integrates it into a Transformer architecture. By incorporating prior knowledge about patch location, our model improves state of the art by ~2 points on the Dice score when integrated with the standard U-Net architecture. The source code of our proposal is publicly released
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