363 research outputs found
CAMPP Pandemic Preparedness: Landing on a short runway
No full text<p>This is Sumit Chanda's presentation at the monthly [virtual] Antiviral Drug Discovery (AViDD) Open Science Forum on 2024-01-17. Their talk is titled "CAMPP Pandemic Preparedness: Landing on a short runway."<br><br>You can find a recording of their talk on the [AViDD Open Science Forum Youtube page](https://www.youtube.com/channel/UCDwwIkoBVkqzVYn0t5AWmeQ/featured)<br><br>Sumit Chanda is a part of the CAMPP AViDD Center.</p>
CAMPP Pandemic Preparedness: Landing on a short runway
No full text<p>This is Sumit Chanda's presentation at the monthly [virtual] Antiviral Drug Discovery (AViDD) Open Science Forum on 2024-01-17. Their talk is titled CAMPP Pandemic Preparedness: Landing on a short runway."<br><br>You can find a recording of their talk on the AViDD Open Science Forum Youtube page: https://youtu.be/1V8ZQqYofNE</p>
<p>Sumit Chanda is a part of the CAMPP AViDD Center.</p>
A probability-based approach for the analysis of large-scale RNAi screens
No full textThis is the companion web site for publication:König R, Chiang CY, Tu BP, Yan SF, DeJesus PD, Romero A, Bergauer T, Orth A, Krueger U, Zhou Y, Chanda SK. A probability-based approach for the analysis of large-scale RNAi screens. Nat Methods. 2007 Oct;4(10):847-9. doi: 10.1038/nmeth1089. Epub 2007 Sep 9. PMID: 17828270.Download and unzip the file, open RSA/index.html to browse the self-contained web site.</div
Performance analysis of the WiNC2R platform:
No full textA Cognitive Radio (CR) is an intelligent transceiver device, able to support multiple technologies, dynamic re-configurability, ease of programming and collaboration with other CR devices to improve the communication efficiency. The two key requirements for an efficient CR implementation are flexibility in operation/programming and speed.
WiNC2R (Winlab Network Centric Cognitive Radio) achieves high speed of operation using its hardware platform and flexibility using its software-configurable architecture. The current WiNC2R architecture implements an 802.11a-like OFDM flow. We evaluate the WiNC2R hardware architecture to see the modularity in the architecture, separation of data and control flow and the performance in terms of latency and throughput. To test the system, the Xilinx Bus Functional Model environment, which is designed to test the IBM standard bus-architecture-based hardware systems, is used. We use a simple ALOHA protocol in the MAC layer to communicate between two WiNC2R nodes and evaluate the performance under the best-case scenario, where the performance is only hindered by the architecture itself rather than external conditions like channel state.
The results of our basic experiments showed that for a single OFDM 802.11a-like flow, the Unit Control Modules (UCM) were idle for almost 80% of the total processing time.
We then tested the WiNC2R system to study the effects of changing the frame size. It was seen that the latencies in the WiNC2R transmitter are frame-size dependent while those in the receiver mainly depend on the size of the data in the last chunk rather than the size of the whole frame. We suggest that chunk size should be 2 OFDM symbols, and chunking be moved to MAC layer for better performance. We give analytical estimates of resulting performance improvement. In the next experiment, we describe virtualization in the WiNC2R by adding more flows. We describe the steps to implement the additional flows and estimate maximum number of concurrent flows possible.
In the last analysis, we show the effect of operating clock frequency on the performance. We prove that at 250 MHz operating frequency and 2 OFDM symbols per chunk, the current WiNC2R implementation will be able to satisfy the SIFS criterion.M.S.Includes bibliographical references (p. 72-73)by Sumit Satarka
The Mechanical Properties of a Pulverized Fuel Ash Blended Cement Paste.
No full textThis thesis describes the results of an investigation carried out to compare the effects on the mechanical properties of Ordinary Portland Cement paste (OPC) when partially replaced by Pulverized Fuel Ash (OPC + 25 wt. % PFA). This was done by evaluating a number of parameters at times between 1 day and 1 year at 20 C. At comparatively early ages the OPC+PFA was found to be weaker (in flexural strength), less stiff (in three point bend), and less tough (in stress intensity factor), and vice versa at later ages. However it was also found that flexural strength and stress intensity factor displayed maxima at ~28 days. The effects of increasing the water/solids ratio and of increasing the curing temperature to 50C were also investigated. These experiments were extended to check on the validity of the above parameters in describing the fracturing process. Changing the sizes and notch depths of stress intensity factor specimens illustrated the non-applicability of linear elastic fracture mechanics (LEFM) to OPC pastes. The observation of a process zone by diffuse illumination optical microscopy (DIM), and of Pe/Pf being <100% (a measure of non-linearity in a load/displacement curve in the stress intensity factor experiments) confirmed this view. A "tied crack" model was applied to explain this behaviour up to ~28 days. Between ~28 days and one year this model had to be modified to incorporate microcrack formation due to internal stress generation and other causes which resulted from continued hydration. The OPC+PFA displayed less microcracking, which could be ascribed to consumption of calcium hydroxide in the pozzolanic reaction and the spherical nature of the PFA. The microstructure was investigated by scanning electron microscopy which gave valuable supporting evidence to the theories discussed above. Overall, the OPC+PFA gave better mechanical properties by one year
The Mechanical Properties of a Pulverized Fuel Ash Blended Cement Paste.
No full textThis thesis describes the results of an investigation carried out to compare the effects on the mechanical properties of Ordinary Portland Cement paste (OPC) when partially replaced by Pulverized Fuel Ash (OPC + 25 wt. % PFA). This was done by evaluating a number of parameters at times between 1 day and 1 year at 20 C. At comparatively early ages the OPC+PFA was found to be weaker (in flexural strength), less stiff (in three point bend), and less tough (in stress intensity factor), and vice versa at later ages. However it was also found that flexural strength and stress intensity factor displayed maxima at ~28 days. The effects of increasing the water/solids ratio and of increasing the curing temperature to 50C were also investigated. These experiments were extended to check on the validity of the above parameters in describing the fracturing process. Changing the sizes and notch depths of stress intensity factor specimens illustrated the non-applicability of linear elastic fracture mechanics (LEFM) to OPC pastes. The observation of a process zone by diffuse illumination optical microscopy (DIM), and of Pe/Pf being <100% (a measure of non-linearity in a load/displacement curve in the stress intensity factor experiments) confirmed this view. A "tied crack" model was applied to explain this behaviour up to ~28 days. Between ~28 days and one year this model had to be modified to incorporate microcrack formation due to internal stress generation and other causes which resulted from continued hydration. The OPC+PFA displayed less microcracking, which could be ascribed to consumption of calcium hydroxide in the pozzolanic reaction and the spherical nature of the PFA. The microstructure was investigated by scanning electron microscopy which gave valuable supporting evidence to the theories discussed above. Overall, the OPC+PFA gave better mechanical properties by one year
The Mechanical Properties of a Pulverized Fuel Ash Blended Cement Paste.
No full textThis thesis describes the results of an investigation carried out to compare the effects on the mechanical properties of Ordinary Portland Cement paste (OPC) when partially replaced by Pulverized Fuel Ash (OPC + 25 wt. % PFA). This was done by evaluating a number of parameters at times between 1 day and 1 year at 20 C. At comparatively early ages the OPC+PFA was found to be weaker (in flexural strength), less stiff (in three point bend), and less tough (in stress intensity factor), and vice versa at later ages. However it was also found that flexural strength and stress intensity factor displayed maxima at ~28 days. The effects of increasing the water/solids ratio and of increasing the curing temperature to 50C were also investigated. These experiments were extended to check on the validity of the above parameters in describing the fracturing process. Changing the sizes and notch depths of stress intensity factor specimens illustrated the non-applicability of linear elastic fracture mechanics (LEFM) to OPC pastes. The observation of a process zone by diffuse illumination optical microscopy (DIM), and of Pe/Pf being <100% (a measure of non-linearity in a load/displacement curve in the stress intensity factor experiments) confirmed this view. A "tied crack" model was applied to explain this behaviour up to ~28 days. Between ~28 days and one year this model had to be modified to incorporate microcrack formation due to internal stress generation and other causes which resulted from continued hydration. The OPC+PFA displayed less microcracking, which could be ascribed to consumption of calcium hydroxide in the pozzolanic reaction and the spherical nature of the PFA. The microstructure was investigated by scanning electron microscopy which gave valuable supporting evidence to the theories discussed above. Overall, the OPC+PFA gave better mechanical properties by one year
Query optimization in mobile environments
No full textWe consider the issue of optimizing queries for distributed processing in mobile environment. An interesting characteristic of mobile machines is that they depend on battery as a source of energy which may not be substantial enough. Hence, the appropriate optimization criterion in a mobile environment considers both resource utilization and energy consum- ption at the mobile client.
In this scenario, the optimal plan for a query depends on the residual battery level of the mobile client and the load at the server. We approach this problem by compiling a query into a sequence of candidate plans, such that for any state of the client-server system, the optimal plan is one of the candidate plans.
A general solution is proposed by adapting the partial order dynamic programming search algorithm (p.o dp) such that the coverset of the query is the set of candidate plans. We propose two novel algorithms, namely, the linear combinations algorithm and the linearset algorithm (referred to as the linear algorithms) that compute the linearset of a query. The linear- set of a query is an approximation to the coverset returned by p.o. dp.
We show, by means of simulation, that (1) the linearset is an excellent approximation of the coverset, (2) query compilation using the linear algorithms outperform query compilation using p.o. dp by factors ranging from 2 to 9, (3) the time taken to compile queries using the linear algorithms for the general optimization criterion is at most twice the time taken by a System R* like standard query optimizer search algorithm, and (4) the run time overhead incurred by the linear algorithms technique is minimal.
The techniques presented in the paper are of general applicability to multi-criterion optimization problems in distributed databases, where each criterion is an additive metric.Technical report lcsr-tr-21
Interactive machine learning for complex graphics selection
No full textThesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 89-91).Modern vector graphics editors support the creation of a wonderful variety of complex designs and artwork. Users produce highly realistic illustrations, stylized representational art, even nuanced data visualizations. In light of these complex graphics, selections, representations of sets of objects that users want to manipulate, become more complex as well. Direct manipulation tools that artists and designers find accessible and useful for editing graphics such as logos and icons do not have the same applicability in these more complex cases. Given that selection is the first step for nearly all editing in graphics, it is important to enable artists and designers to express these complex selections. This thesis explores the use of interactive machine learning techniques to improve direct selection interfaces. To investigate this approach, I created Insight, an interactive machine learning selection tool for making a relevant class of complex selections: visually similar objects. To make a selection, users iteratively provide examples of selection objects by clicking on them in the graphic. Insight infers a selection from the examples at each step, allowing users to quickly understand results of actions and reactively shape the complex selection. The interaction resembles the direct manipulation interactions artists and designers have found accessible, while helping express complex selections by inferring many parameter changes from simple actions. I evaluated Insight in a user study of digital designers and artists, finding that Insight enabled users to effectively and easily make complex selections not supported by state-of-the-art vector graphics editors. My results contribute to existing work by both indicating a useful approach for providing complex representation access to artists and designers, and showing a new application for interactive machine learning.by Sumit Gogia.M. Eng
<b>Numerical Analysis of Recoverable Negative Stiffness Smart Structures for Energy Absorption in Shock Isolation</b>
No full textThe recently developed Negative Stiffness Honeycomb (NSH) structures have drawn tremendous interest in the field of energy absorption and shock isolation. The smart NSH structures have the advantage of being reused multiple times, where the conventional energy absorption techniques involve permanent deformation of the material via linear or nonlinear buckling or failure mode to absorb energy. In this study, the force-displacement characteristics of NSH structure with different materials has been investigated using Finite Element Method Based Software. A comprehensive investigation was undertaken to analyze the performance of the structure as energy absorbers in displacement-controlled loading conditions. From the obtained results it was observed that the NSH structure shows good energy absorption without crushing. The energy absorption characteristics were analyzed for different flexible materials commonly used in additive manufacturing. Since the structure is recoverable after each unloading, with required specific energy absorption, these structures can be used for shock isolation in sensitive structures such as small containers, packaging, small shock absorbers etc.</p
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