An Analysis of Scale Invariance in Object Detection - SNIP

An analysis of different techniques for recognizing and detecting objects under extreme scale variation is presented. Scale specific and scale invariant design of detectors are compared by training them with different configurations of input data. By evaluating the performance of different network architectures for classifying small objects on ImageNet, we show that CNNs are not robust to changes in scale. Based on this analysis, we propose to train and test detectors on the same scales of an image-pyramid. Since small and large objects are difficult to recognize at smaller and larger scales respectively, we present a novel training scheme called Scale Normalization for Image Pyramids (SNIP) which selectively back-propagates the gradients of object instances of different sizes as a function of the image scale. On the COCO dataset, our single model performance is 45.7% and an ensemble of 3 networks obtains an mAP of 48.3%. We use off-the-shelf ImageNet-1000 pre-trained models and only train with bounding box supervision. Our submission won the Best Student Entry in the COCO 2017 challenge. Code will be made available at \url{http://bit.ly/2yXVg4c}.Comment: CVPR 2018, camera ready versio

Underdeveloped Spot Markets and Futures Trading: The Soya Oil Exchange in India

Abstract The limited presence of futures exchanges in developing countries where commodity markets fall short of the ideal underscore the importance of understanding the relation between spot and futures markets. The paper examines the exceptional success of the soya oil contract at the National Board of Trade (NBOT) in India. The paper asks whether the NBOT contract exhibits the fundamental features of mature futures markets in terms of its use by hedgers. If the market offers arbitrage opportunities to hedgers and if such activity is significant, then the activities of commercial firms should affect the returns to their hedging portfolio i.e., change in basis. This insight is developed into an examination of the impact of soya oil imports on the basis. Despite the lack of key market institutions such as certified warehouses and centralized spot prices, the NBOT contract compares well with mature exchanges. Soya oil imports exercise a significant impact on the basis and provide enough short-term volatility to make the contract attractive to both hedgers and speculators.basis, hedging, futures market, spot markets, soya oil, Marketing, G13, Q13,

Prospects of detecting HI using redshifted 21 cm radiation at z ~ 3

Distribution of cold gas in the post-reionization era provides an important link between distribution of galaxies and the process of star formation. Redshifted 21 cm radiation from the Hyperfine transition of neutral Hydrogen allows us to probe the neutral component of cold gas, most of which is to be found in the interstellar medium of galaxies. Existing and upcoming radio telescopes can probe the large scale distribution of neutral Hydrogen via HI intensity mapping. In this paper we use an estimate of the HI power spectrum derived using an ansatz to compute the expected signal from the large scale HI distribution at z ~ 3. We find that the scale dependence of bias at small scales makes a significant difference to the expected signal even at large angular scales. We compare the predicted signal strength with the sensitivity of radio telescopes that can observe such radiation and calculate the observation time required for detecting neutral Hydrogen at these redshifts. We find that OWFA (Ooty Wide Field Array) offers the best possibility to detect neutral Hydrogen at z ~ 3 before the SKA (Square Kilometer Array) becomes operational. We find that the OWFA should be able to make a 3 sigma or a more significant detection in 2000 hours of observations at several angular scales. Calculations done using the Fisher matrix approach indicate that a 5 sigma detection of the binned HI power spectrum via measurement of the amplitude of the HI power spectrum is possible in 1000 hours (Sarkar, Bharadwaj and Ali, 2017).Comment: 13 pages, six figures. To appear in special issue on Ooty Wide Field Array (OWFA) in Journal of Astrophysics and Astronomy (March 2017

Current collection in a flowing magnetoplasma

Effects of plasma drift on the current collection by a long conducting cylinder in a magnetized plasma is studied by means of a 2 1/2 dimensional PIC code. It is found that for the drift velocity (V sub 0) perpendicular to the magnetic field (B sub 0), the electron current collected by a positive cylinder is considerably enhanced depending on the drift velocity. The distributions of plasma and the potential structure around the cylinder for several relative orientations between V sub 0 and B are presented along with the comparisons of current with and without the magnetic field. Simulations with the magnetic field in the simulation plane show that the potential structures around the cylinder are two-dimensional double layers with dimension (L) perpendicular to B much smaller than the dimension (L) parallel to B. In fact, L perpendicular is found to be approximately determined by the current limiting radius given by the Parker-Murphy model. However, it is found that the collected currents in the simulations are generally higher than those given by this model

Underdeveloped spot markets and futures trading: The Soya Oil exchange in India

The limited presence of futures exchanges in developing countries where commodity markets fall short of the ideal underscore the importance of understanding the relation between spot and futures markets. The paper examines the exceptional success of the soya oil contract at the National Board of Trade (NBOT) in India. The paper asks whether the NBOT contract exhibits the fundamental features of mature futures markets in terms of its use by hedgers. If the market offers arbitrage opportunities to hedgers and if such activity is significant, then the activities of commercial firms should affect the returns to their hedging portfolio i.e., change in basis. This insight is developed into an examination of the impact of soya oil imports on the basis. Despite the lack of key market institutions such as certified warehouses and centralized spot prices, the NBOT contract compares well with mature exchanges. Soya oil imports exercise a significant impact on the basis and provide enough short-term volatility to make the contract attractive to both hedgers and speculators.hedging, futures markets, spot markets, soya oil

Fast-AT: Fast Automatic Thumbnail Generation using Deep Neural Networks

Fast-AT is an automatic thumbnail generation system based on deep neural networks. It is a fully-convolutional deep neural network, which learns specific filters for thumbnails of different sizes and aspect ratios. During inference, the appropriate filter is selected depending on the dimensions of the target thumbnail. Unlike most previous work, Fast-AT does not utilize saliency but addresses the problem directly. In addition, it eliminates the need to conduct region search on the saliency map. The model generalizes to thumbnails of different sizes including those with extreme aspect ratios and can generate thumbnails in real time. A data set of more than 70,000 thumbnail annotations was collected to train Fast-AT. We show competitive results in comparison to existing techniques

Efficiency and distribution in contract farming:The case of Indian poultry growers

This paper is an empirical analysis of the gains from contract farming in the case of poultry production in the state of Andhra Pradesh in India. The paper finds that contract production is more efficient than noncontract production. The efficiency surplus is largely appropriated by the processor. Despite this, contract growers still gain appreciably from contracting in terms of lower risk and higher expected returns. Improved technology and production practices as well as the way in which the processor selects growers is what makes these outcomes possible. In terms of observed and unobserved characteristics, contract growers have relatively poor prospects as independent growers. With contract production, these growers achieve incomes comparable to that of independent growersContract Farming, Contracting, Poultry, Vertical Integration