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Irvine, CA, United States

Mahalingam A.,Indian Institute of Technology Madras | Kashyap R.,Cushman and Wakefield India Pvt. Ltd. | Mahajan C.,ECC
Automation in Construction | Year: 2010

4D CAD models that integrate physical 3D elements with time, have been used to visualize construction processes in several projects worldwide. 4D models have been used and have been shown to have benefits over processes that span the entire lifecycle of a project such as collaboration with stakeholders, making design decisions, assessing project constructability, identifying spatial conflicts in construction and so on. Despite these benefits, several organizational and project-specific barriers have hindered the widespread adoption of 4D CAD. In order to reconcile the theoretical benefits of 4D models with the practical difficulties faced in implementation, there is an urgent need to explore the implementation of 4D models on construction sites as well as the perceptions of intended users/beneficiaries towards this implementation. This paper aims to address this need and contribute to our understanding of how 4D models must be introduced, positioned and implemented on construction sites, so as to maximize both their acceptability and their usefulness. We describe two 4D models of infrastructure projects and two 4D models of commercial projects that have been built and implemented. Through a process of structured and unstructured interviewing the paper gauges the response of project participants across various organizational levels on each of these projects as to the usefulness of 4D in project planning and control. Through qualitative and statistical analysis of the data we establish that 4D CAD is likely to be most beneficial in the project shaping or planning stage and in the construction stage. In the project shaping stage, 4D CAD is likely to be particularly useful in communicating construction plans and processes to clients, while during the construction phase, 4D CAD is likely to be particularly useful in comparing the constructability of work methods visually in order to detect conflicts or clashes, and as a visual tool for contractors, clients, subcontractors and vendors to review and plan project progress. Further, upper management and site workers are more likely to use and derive benefits from the visualization of processes using 4D given their lack of site related knowledge or skills, while construction professionals who are more construction-savvy are more likely to appreciate and benefit from the analytical and planning aids that 4D simulations provide during the construction phase. However, it is likely that despite these benefits 4D CAD models might not diffuse through the construction industry unless 4D modelling and analysis is integrated into existing project planning approaches. The paper concludes with a brief discussion on future 4D software development that seeks to bring about such integration and leverages the benefits of 4D CAD to bring about improved operational efficiencies on construction sites. © 2009 Elsevier B.V. All rights reserved. Source


Anderson S.,ECC
Concrete (London) | Year: 2010

Some of the significant benefits of tilt-up construction and site-up cast concrete wall panels were utilized to undertake a project to construct a new Marine Forces Reserve HQ for the US Marine Corps In New Orleans. The US$110 million, four-storey, 411,000ft2 MarForRes building formed the main part of the Federal City complex being developed in New Orleans on the west bank of the Mississippi River. Woodward Design+Build was selected as the design-builder for Phase I of Federal City that included construction of the new facility for the Marine Forces Reserve. Support functions included provisions for 1400 residential units, a child care center, food services, athletic and recreational facilities, security, five educational institutions spanning elementary to college level, and a town center. The concept also planned on establishing an aesthetically attractive, campus-type environment on the installation that was to improve working environment significantly. Source


Azhagurajan A.,Mepco Schlenk Engineering College, Sivakasi | Selvakumar N.,Mepco Schlenk Engineering College, Sivakasi | Mohammed Yasin M.,ECC
Process Safety Progress | Year: 2012

The minimum ignition energy (MIE) of dust clouds is required to assess the electrostatic ignition risk. Recently, the growing number of accidents shows that fire and explosions occurring in fireworks industry are due to electrostatic discharge (ESD). The objective of the this paper is to discuss the various practical concerns during the handling of flash powders of various compositions containing potassium nitrate, sulfur, and aluminum in fireworks. These powders form dust clouds and cause fires and explosions because the MIEs of these dust clouds are very low. This study is carried out with powders of various sizes ranging from micron and nanometer. The measurements are done by using a 1.2-L Hartmann apparatus. The experimental results show that the MIEs for flash powders are in the range from 89.2 to 19.8 mJ for micron- and nano-sized particles. The experimental results are given for various changes, such as: electrode gap, electrode material, and dust concentration, dust composition, etc. If the nano flash powder is mixed with micron powders, the MIE is greatly reduced, and it becomes extremely combustible. Therefore, it is imperative for fireworks manufacturers, or anyone handling these dusts, to take precautionary measures to prevent fires and explosions involving ESDs. © 2011 American Institute of Chemical Engineers (AIChE). Source


Mate S.N.,ECC
2nd International Conference on Electronics and Communication Systems, ICECS 2015 | Year: 2015

Identification problem of time varying system can be solved by conventional recursive estimation approach and wavelet based recursive estimation approach. In Wavelet based recursive estimation approach each time varying parameter is approximated by using multi-wavelet basis functions. The identification problem is then converted into time invariant system identification problem which can be solved by regression selection and parameter estimation using block LMS algorithm. This approach gives improved tracking performance for rapidly varying systems as compared to conventional recursive estimation approach by using LMS algorithm. © 2015 IEEE. Source


News Article
Site: http://phys.org/technology-news/

Plot of CPU transistor counts against dates of introduction; note the logarithmic vertical scale; the line corresponds to exponential growth with transistor count doubling every two years. Credit: Wikipedia For past several decades, the processor industry has enjoyed the benefits of chip miniaturization and the exponential increase in the number of on-chip transistors as predicted by Moore's law. However, as process technology scales to small feature sizes, precise control of fabrication processes has become increasingly difficult. As a result, 'process variation' (PV), which refers to the deviation in parameters from their nominal specifications, has greatly exacerbated. Above the nearly 350nm technology node, PV had negligible effect on processors, since the magnitude of variation was insignificant compared to the device size. However, with ongoing process scaling, the effect of PV can be seen on all metrics of interest, such as performance, energy and yield. For example, due to PV, the maximum clock frequency of different cores in a 65nm, 80-core Intel processor can vary between 5.7 GHz and 7.3 GHz. Similarly, due to PV, the timing parameters in a DDR3 DRAM device can be up to 66 percent lower than the datasheet specifications. PV can lead to as high as 9X variation in the sleep power in different instances of ARM Cortex M3 processors. In phase change memory (PCM), the write endurance of different cells can vary by up to 50X due to PV. The effect of PV also increases at low voltages and as the supply voltage continues to scale with process scaling (e.g., from 5v at 800nm to ~1.1v at 32nm process technology) or as voltage-scaling approaches become deployed for saving energy, the effect of PV is expected to worsen. In fact, a study reports chip yields reducing from nearly 90 percent at 350nm to 50 percent at the 90nm feature size. It has been estimated that if left unaddressed, PV can wipe out the performance gain obtained from an entire process technology generation. These points are highlighted in a recent survey paper titled, "A Survey Of Architectural Techniques for Managing Process Variation" by ORNL researcher Sparsh Mittal. This paper, accepted in ACM Computing Surveys 2015, investigates the impact of PV along with strategies for mitigating it in a wide range of system architectures, e.g. in CPUs, GPUs, in processor components (cache, main memory, processor core), in memory technologies (SRAM, DRAM, eDRAM, non-volatile memories e.g. PCM, resistive RAM) and in both 2D and 3D processors. The paper also summarizes some commonly used system-level techniques for managing process variation, such as task scheduling, DVFS, use of redundant storage, etc. For example, in multicore processors, the tasks can be scheduled to a core which is least affected by PV. Similarly, higher supply voltage or additional refresh operations can be provisioned for a block most affected by PV. Further, PV-affected parts (e.g. registers or cache blocks) can be disabled and normal or spare parts can instead be used. Also, the faults in PV-affected parts can be corrected by using error-correcting codes (ECC). These techniques have shown significant potential in alleviating the impact of PV on processors. As the quest of ongoing process scaling confronts the formidable challenge of rising process variation, the design of computing systems is likely to undergo a major overhaul. Crossing over these obstacles for designing variation-resilient computing systems is the challenge that awaits us in near future. More information: A Survey Of Architectural Techniques for Managing Process Variation: www.academia.edu/19490711/A_Survey_Of_Architectural_Techniques_for_Managing_Process_Variation

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