Jacobs Engineering Group Inc., is an international engineering, architecture, and construction firm with offices located around the world. As a publicly traded company with 66,000 employees and 2014 revenues of more than $12 billion, Jacobs offers support to industrial, commercial, and government clients across multiple markets. In 2014, Jacobs was named by Forbes as one of America's 100 Most Trustworthy Companies. Annual revenues have made Jacobs Engineering a Fortune 500 Company. Wikipedia.
Elgala H.,Jacobs Engineering |
Mesleh R.,University of Tabuk |
Haas H.,University of Edinburgh
IEEE Communications Magazine | Year: 2011
In recent years, interest in optical wireless (OW) as a promising complementary technology for RF technology has gained new momentum fueled by significant deployments in solid state lighting technology. This article aims at reviewing and summarizing recent advancements in OW communication, with the main focus on indoor deployment scenarios. This includes a discussion of challenges, potential applications, state of the art, and prospects. Related issues covered in this article are duplex transmission, multiple access, MAC protocols, and link capacity improvements. © 2011 IEEE.
Mukhopadhyay B.,Jacobs Engineering
Hydrological Processes | Year: 2013
A prevailing perception is that the glaciers and perennial snow and ice covered areas (SCAP) or in the Himalayan region are fast contracting. However, systematic studies providing the quantitative estimates of SCAP as a function of time within individual river basins are lacking. The importance of meltwater in river flows varies greatly from one river basin to another, yet the actual estimates of those contributions are largely unknown. This study bridges such knowledge gaps for the upper-middle Brahmaputra Basin by using best available digital cartographic and remotely sensed snow cover data. We find that when the entire basin is considered, SCAP decreased from 7637±764 in 1980 to 4298±1422km2 in 1992. However, it has increased to 7160±2248km2 in 2000. From 2000 to 2010, the SCAP has remained nearly constant around a mean of 10052±1468km2. The same trend is observed within individual physiographic zones of the basin. Such increase in SCAP is due to the increase in the precipitation over the middle Brahmaputra Basin and the Nyainquentanglha Mountains, as observed in station records. The incursion of moist air through the Brahmaputra valley to the higher elevations within the Nyainquentanglha Mountains causes snowfall during pre-monsoonal and post-monsoonal seasons and an expansion of the SCAP. Glacial expansions in the Nyainquentanglha Mountains have also been observed in other recent studies. In addition to the increase in precipitation and SCAP, another manifestation of climate change observed in this basin is the increasing temperature with a mean annual trend of +0.28°C/decade. The hydrologic consequences of the observed effects of climate change are expected to be an insignificant change in streamflows in the watersheds drained by the upper Brahmaputra River but a perceptible increase in river discharges in the watersheds drained by the middle Brahmaputra River and its tributaries, particularly within the upper and lower catchments of the middle Brahmaputra Basin. © 2012 John Wiley & Sons, Ltd.
Llewellyn Smith S.G.,Jacobs Engineering
Physica D: Nonlinear Phenomena | Year: 2011
The equations of motion of point vortices embedded in incompressible flow go back to Kirchhoff. They are a paradigm of reduction of an infinite-dimensional dynamical system, namely the incompressible Euler equation, to a finite-dimensional system, and have been called a "classical applied mathematical playground". The equation of motion for a point vortex can be viewed as the statement that the translational velocity of the point vortex is obtained by removing the leading-order singularity due to the point vortex when computing its velocity. The approaches used to obtain this result are reviewed, along with their history and limitations. A formulation that can be extended to study the motion of higher singularities (e.g. dipoles) is then presented. Extensions to more complex physical situations are also discussed. © 2011 Elsevier B.V. All rights reserved.
Mukhopadhyay B.,Jacobs Engineering
Journal of Hydrology | Year: 2012
In river basins where melt water from snow and ice constitutes a dominant component of stream discharge during summer, degradation or reduction of perennial snow and ice covered areas (SCA P) has a profound effect on stream water availability in those basins. Degradation of SCA P that includes glaciers is a globally widespread phenomenon observed in the recently past decades; its cause has been attributed to global warming and its consequence is expected to dramatically alter the flow regimes of the rivers draining the terrains. The predicted change in flow regime is an initial increase in summer flows in the early decades of 21st century followed by sharp decline of the same during the later parts of the century. Estimation of SCA P within the Upper Indus Basin (UIB), straddling the western ranges of the Greater Himalayas, Karakoram Mountains, and the eastern mountain ranges of the Hindu Kush, shows that from 1992 to 2010 there has been about 2.15% reduction in SCA P. A spatially distributed basin-scale stream water availability model is presented to calculate monthly river discharges at critical hydrologic junctions within UIB. Model calculations for the years 1992, 2000, and 2008, show that due to the degradation of the SCA P within the basin, there has been significant decrease in summer discharges at various hydrologic junctions. The percentage decline in flows varies from 10% to 22%, depending on the locations of the junctions within the basin. The space-dependence of these variations reflects differential degradation of SCA P in various parts of the basin. Furthermore, the time of peak discharge at all of the hydrological junctions has shifted from middle/late summer to late spring/early summer as another outcome of SCA P reduction. Such temporal shifting of nival regimes to early part of warmer season has also been predicted by global warming models. However, the case study presented here for a major Himalayan river basin demonstrates that such shifting of peak discharge in the time domain can also take place simply due to retreat of the equilibrium line. Thus, the effects of a warming climate have possibly been already set within UIB. Instead of experiencing an increased pulse of summer flows for the next few decades, summer flows within this basin are expected to decline. Changes in the timing of peak flows can have adverse effects on multipurpose water resources management without appropriate adaptation and mitigation measures. Monthly average stream flow data with 35. year period of record from a key gauging station support the findings of the model results. Similarly, digital maps of SCA P at different time periods within a key catchment of UIB, containing one of the major glaciers, show retreat of glacial lobes and significant decrease in total SCA P taking place during the past decades. © 2011 Elsevier B.V.
Teeling H.,Max Planck Institute for Marine Microbiology |
Glockner F.O.,Jacobs Engineering
Briefings in Bioinformatics | Year: 2012
Metagenomics has become an indispensable tool for studying the diversity and metabolic potential of environmental microbes, whose bulk is as yet non-cultivable. Continual progress in next-generation sequencing allows for generating increasingly large metagenomes and studying multiple metagenomes over time or space. Recently, a new type of holistic ecosystem study has emerged that seeks to combine metagenomics with biodiversity, meta-expression and contextual data. Such 'ecosystems biology' approaches bear the potential to not only advance our understanding of environmental microbes to a new level but also impose challenges due to increasing data complexities, in particular with respect to bioinformatic post-processing. This mini review aims to address selected opportunities and challenges of modern metagenomics from a bioinformatics perspective and hopefully will serve as a useful resource for microbial ecologists and bioinformaticians alike. © The Author 2012. Published by Oxford University Press.