A differential memristive synapse circuit for on-line learning in neuromorphic computing systems

Spike-based learning with memristive devices in neuromorphic computing architectures typically uses learning circuits that require overlapping pulses from pre- and post-synaptic nodes. This imposes severe constraints on the length of the pulses transmitted in the network, and on the network's throughput. Furthermore, most of these circuits do not decouple the currents flowing through memristive devices from the one stimulating the target neuron. This can be a problem when using devices with high conductance values, because of the resulting large currents. In this paper we propose a novel circuit that decouples the current produced by the memristive device from the one used to stimulate the post-synaptic neuron, by using a novel differential scheme based on the Gilbert normalizer circuit. We show how this circuit is useful for reducing the effect of variability in the memristive devices, and how it is ideally suited for spike-based learning mechanisms that do not require overlapping pre- and post-synaptic pulses. We demonstrate the features of the proposed synapse circuit with SPICE simulations, and validate its learning properties with high-level behavioral network simulations which use a stochastic gradient descent learning rule in two classification tasks.Comment: 18 Pages main text, 9 pages of supplementary text, 19 figures. Patente

A neuromorphic systems approach to in-memory computing with non-ideal memristive devices: From mitigation to exploitation

Memristive devices represent a promising technology for building neuromorphic electronic systems. In addition to their compactness and non-volatility features, they are characterized by computationally relevant physical properties, such as state-dependence, non-linear conductance changes, and intrinsic variability in both their switching threshold and conductance values, that make them ideal devices for emulating the bio-physics of real synapses. In this paper we present a spiking neural network architecture that supports the use of memristive devices as synaptic elements, and propose mixed-signal analog-digital interfacing circuits which mitigate the effect of variability in their conductance values and exploit their variability in the switching threshold, for implementing stochastic learning. The effect of device variability is mitigated by using pairs of memristive devices configured in a complementary push-pull mechanism and interfaced to a current-mode normalizer circuit. The stochastic learning mechanism is obtained by mapping the desired change in synaptic weight into a corresponding switching probability that is derived from the intrinsic stochastic behavior of memristive devices. We demonstrate the features of the CMOS circuits and apply the architecture proposed to a standard neural network hand-written digit classification benchmark based on the MNIST data-set. We evaluate the performance of the approach proposed on this benchmark using behavioral-level spiking neural network simulation, showing both the effect of the reduction in conductance variability produced by the current-mode normalizer circuit, and the increase in performance as a function of the number of memristive devices used in each synapse.Comment: 13 pages, 12 figures, accepted for Faraday Discussion

Instabilities of Decelerating Flow

This paper numerically investigates the instability characteristics of decelerating flows. The flow dynamics and temporal evolution of coherent structures in a diverging section with mild spatial pressure gradient are analyzed using numerical experiments with Incompact3d code. The unsteady nature of flow and adverse pressure gradient is the reason for inflectional velocity profiles, results into boundary layer separation and instability with reverse flow and later on it leads to vortex formation. Vortex formation time is found by vortex Reynold's number. Time of first vortex formation, non-dimensional vortex formation times with Reynold's number etc. are validated with an experimental results.Comment: Proceedings of the 25th National and 3rd International ISHMT-ASTFE Heat and Mass Transfer Conference (IHMTC-2019

Progress in superconductivity: The Indian Scenario

India has made rapid progress in the field of high temperature superconductivity, beginning at the time of publication of the Zeitschrift fur Physik paper by Bednorz and Muller. Phase 1 of the program was conceived by the Department of Science & Technology of the Government of India. It consisted of 42 projects in the area of basic research, 23 projects in applications and 4 short-term demonstration studies. The second phase started in October 1991 and will run through March 1995. It consists of 50 basic research programs and 24 application programs. The total investment, mainly consisting of infrastructural development to supplement existing facilities and hiring younger people, has amounted to about Indian Rupees 40 crores, equivalent to about US$13 million. The expenditure for the period 1992-1997 shall be up to about Rs. 27 crores, equivalent to about US$ 9 million. The basic idea is to keep pace with developments around the world

Marine fish landings in Odisha during 2016 - An overview

The state of Odisha has a long coast line of 480 km with numerous fisheries harbours and fish landing centres like Paradeep, Bahabalapur, Dhamra, Atharabanki, Nuagarh, Bada Arjipally etc. According to Marine Fisheries Census 2010, there are 1.14 lakh fishermen families with 3.95 lakh fisherfolk engaged in actual fishing activities. In 2016, the marine fish production in Odisha was 1.17 lakh tonnes (t) showing a decrease of 17% over the previous year

Tensor fascia lata muscle pedicle grafting for avascular necrosis femoral head

Background: Osteonecrosis of femoral head (AVN) is a disabling condition with ill-defined etiology and pathogenesis. In more than 60% it leads to osteoarthritis of hip joint. Treatment for this condition includes both operative and non-operative methods with variable success rates. Surgical options being aimed at both conservation of femoral head and arthroplasty of hip joint. Aim of our study was to evaluate the efficacy of tensor fascia lata muscle pedicle grafting in the management of osteonecrosis of femoral head.Methods: 27 cases with a mean age of 38.7 years (range from 24 to 52) who underwent tensor fascia lata muscle pedicle grafting in the management of  osteonecrosis  of femoral head were prospectively evaluated with a  mean follow up period of  7.3 years (range from 3 to 12 years). Watson-Jones approach was used in all patients. Average hospital stay was 12 days. Harris hip score was used for the evaluation of clinical outcome.Results: In our series of 27 cases, the Harris hip score was excellent (90-100) in 19, good (80-89) in 5, fair (70-79) in 2 and  poor  (<70) in 1 case at final follow up.Conclusions: Tensor fascia lata muscle pedicle grafting is an effective, technically easier, pain relieving head-preserving procedure and will improve outcome in properly selected patients with osteonecrosis of femoral head.

Training Manual Species Identification

This manual has been prepared as a supplementary reference material for the training programme on “Species Identification” conducted as a part of Component – III of Fisheries Management for Sustainable Livelihood (FIMSUL), Phase II, a project supported by the World Bank and implemented by the Department of Fisheries, Government of Tamil Nadu. The training programme was organized by Fishery Resources Assessment Division of ICAR-Central Marine Fisheries Research Institute, Kochi during 20th March to 1st April 2017

Trends in Agricultural Information Management: Web 2.0 and Social Networking

Examining the recent trends Agricultural Information Management, it can be observed that, the advances in technologies, particularly Internet technologies have changed the way information is accessed and disseminated. There is a shift towards more dynamic applications and more interactivity between users. This current shift in web technologies is commonly known currently as Web 2.0. As internet technology has evolved from Web 1.0 to Web 2.0, the manner in which information is generated, accessed, organized, and disseminated has changed. Some of the attributes of Web 2.0 include the growth of social networks, bidirectional communication and significant diversity in types of content. Web 2.0 as a term used to describe websites and services where the content is created partially or entirely by the users. The term Web 2.0 was conceptualized and introduced by Tim O'Reilly and Dale Dougherty. Tim O'Reilly defined web 2.0 as: "the business revolution in the computer industry caused by the move to the internet as platform, and an attempt to understand the rules for success on that new platform

FISH@CMFRI: Training cum workshop on effective use of high performance computing in research with facility for integrated-modeling Simulation and High-end analytics

A high performance computing facility (FISH@CMFRI) with multi-core computing and expansive scalability of big data analytics/streaming data processing architecture was developed at AKMU,ICAR-CMFRI(RoomNo.108) with the following specifications: Computing Capacity:3TFLOPS; No.of Computer Nodes: 4; Total No.of Processors:8; Total No.of Cores:96; Memory per node:64GB;Total RAM:256GB;Total Usable Storage Capacity:4TB;Primary Interconnect:10Gbps Ethernet; Administration and ManagementNetwork: 1Gbps Ethernet; Operating System: Linux RHE

Short and Long-Term Sensitivity of Lab-Scale Thermocline Based Thermal Storage to Flow Disturbances

Molten-salt thermocline-based systems are a low-cost option for single-tank thermal energy storage in concentrated solar power plants. Due to the high variability in solar energy availability, these energy storage devices are subject to transient heat loads during charging that can affect the storage efficiency. Numerical simulations were conducted to analyze the stability characteristics of a lab-scale thermocline tank subject to a flow disturbance during charging under different operating temperatures. The charging process was first simulated at a constant Reynolds number for three different Atwood numbers; a stably stratified fluid layer develops inside the storage tank in all cases. A flow disturbance was then introduced at the inlet of the stratified thermocline tank by inserting colder fluid for a short period of time. The disturbance interacts with the thermocline and causes oscillations and mixing. The thermocline oscillations are under-damped and lead to an increase in thermocline region thickness. The transient behavior of the thermocline and the decay rate in its oscillations were analyzed; the damping time depends on the Atwood number. The persistence of flow disturbance effects during long-term cyclical operation was also investigated. Several charge/discharge cycles were simulated at constant Reynolds number to obtain a time-periodic thermal response for each Atwood number. The characteristic flow disturbance was introduced at the inlet during a single charging process, and the thermocline region was observed during several subsequent charge/discharge cycles to assess the long-term temporal attenuation of the disturbance. The thermocline almost fully recovers to the time-periodic behavior after a single cycle