Synchronization in complex networks

Synchronization processes in populations of locally interacting elements are in the focus of intense research in physical, biological, chemical, technological and social systems. The many efforts devoted to understand synchronization phenomena in natural systems take now advantage of the recent theory of complex networks. In this review, we report the advances in the comprehension of synchronization phenomena when oscillating elements are constrained to interact in a complex network topology. We also overview the new emergent features coming out from the interplay between the structure and the function of the underlying pattern of connections. Extensive numerical work as well as analytical approaches to the problem are presented. Finally, we review several applications of synchronization in complex networks to different disciplines: biological systems and neuroscience, engineering and computer science, and economy and social sciences.Comment: Final version published in Physics Reports. More information available at http://synchronets.googlepages.com

Evidence for two stages of mineralization in West Africa's largest gold deposit: Obuasi, Ghana

The supergiant Obuasi gold deposit is the largest deposit in the Paleoproterozoic Birimian terranes of West Africa with 62 Moz of gold (past production + resources). The deposit is hosted in the Paleoproterozoic Kumasi Group sedimentary rocks composed of carbonaceous phyllites, slates, psammites, and volcaniclastic rocks intruded by different generations of felsic dikes and granites. A three-stage deformation history is defined for the district. The D1Ob stage is weakly recorded in the sedimentary rocks as a layer-parallel fabric and indicates that bedding parallel shearing occurred during the early stage of deformation at Obuasi. The D2Ob is the main deformation stage affecting the Obuasi district and corresponds to a NW-SE shortening. Tight to isoclinal folding, as well as intense subhorizontal stretching, occurred during D2Ob, parallel with the plane of a pervasive NE-striking subvertical foliation (S2Ob). Finally, a N-S shortening event (D3Ob) refolded previously formed structures and formed a distinct ENE-striking, variably dipping S3Ob cleavage that is domainal in nature throughout the deposit. Two economic styles of mineralization occur at Obuasi and contribute equally to the gold budget. These are (1) gold-bearing sulfides, dominantly arsenopyrite, mainly disseminated in metasedimentary rocks and (2) native gold hosted in quartz veins that are as much as 25 m wide. Microstructural evidence, such as strain shadows surrounding gold-bearing arsenopyrite parallel with S2Ob, but folded by S3Ob, indicates that the sulfides were formed during D2Ob. Concentrations of as much as 700 ppm Au are present in the epitaxial growth zones of the arsenopyrite grains. Although the large mineralized quartz veins are boudinaged and refolded (indicating their formation during D2Ob), field and microanalytical observations demonstrate that the gold in the veins is hosted in microcracks controlled by D3Ob, where the S3Ob cleavage crosscuts the quartz veins in the main ore zones. Thus, these observations constitute the first evidence for multiple stages of gold deposition at the Obuasi deposit. Futhermore, three-dimensional modeling of stratigraphy, structure, and gold orebodies highlights three major controls on oreshoot location, which are (1) contacts between volcaniclastic units and pre-D1 felsic dikes, (2) fault intersections, and (3) F3Ob fold hinges. The maximum age for the older disseminated gold event is given by the age of the granites at 2105 ± 2 Ma, which is within error of hydrothermal rutile in the granites of 2098 ± 7 Ma; the absolute age of the younger gold event is not known

Variscan and Alpine structure of the hills of Barcelona: geology in an urban area

Line 9 of the underground railway is currently being constructed in Barcelona. This undertaking necessitates tunnelling through a number of hills that are mainly made up of Paleozoic rocks, which exhibit a complex structure due to the superposition of Variscan, Mesozoic, Paleogene, and Neogene structures. We present a geological map of the hills of Barcelona originally compiled at 1:5000 scale. Unpublished field notes from surveys carried out in the 1940s and in the early 1970s were crucial for drawing up this detailed map, which together with subsurface data from public works and our study of the few remaining outcrops, enabled us to provide fresh insights into the structure of this area. We also discuss the age of the structures on the basis of cross-cutting relationships and regional considerations. Our conclusions highlight the ongoing need for a geological survey of cities given that our understanding of their geology depends on impermanent outcrops and on the recovery of lost subsurface data. These considerations call for a suitable management of the geological information in urban areas with a complex geology for planning and developing safe infrastructures

The Impact of Requirements on Systems Development Speed: A Multiple-Case Study in Automotive

Automotive\ua0manufacturers have historically adopted rigid\ua0requirements\ua0engineering processes. This allowed them to meet safety-critical\ua0requirements\ua0when producing\ua0a\ua0highly complex and differentiated product out of the integration of thousands of physical and software components. Nowadays, few software-related domains are as rapidly changing as the\ua0automotive\ua0industry.\ua0In\ua0particular, the needs of improving\ua0development\ua0speed\ua0are increasingly pushing companies\ua0in\ua0this domain toward new ways of developing software.\ua0In\ua0this paper, we investigate how the goal to increase\ua0development\ua0speed\ua0impacts how\ua0requirements\ua0are managed\ua0in\ua0the\ua0automotive\ua0domain. We start from\ua0a\ua0manager perspective, which we then complement with\ua0a\ua0more general perspective. We used\ua0a\ua0qualitative\ua0multiple-case\ua0study, organized\ua0in\ua0two steps.\ua0In\ua0the first step, we had 20 semi-structured interviews, at two\ua0automotive\ua0manufacturers. Our sampling strategy focuses on manager roles, complemented with technical specialists.\ua0In\ua0the second step, we validated our results with 12 more interviews, covering nine additional respondents and three recurring from the first step.\ua0In\ua0addition to validating our qualitative model, the second step of interviews broadens our perspective with technical experts and change managers. Our respondents indicate and rank six aspects of the current\ua0requirements\ua0engineering approach that\ua0impact\ua0development\ua0speed. These aspects include the negative\ua0impact\ua0of\ua0a\ua0requirements\ua0style dominated by safety concerns as well as decomposition of\ua0requirements\ua0over many levels of abstraction. Furthermore, the use of\ua0requirements\ua0as part of legal contracts with suppliers is seen as hindering fast collaboration. Six additional suggestions for potential improvements include domain-specific tooling, model-based\ua0requirements, test automation, and\ua0a\ua0combination of lightweight upfront\ua0requirements\ua0engineering preceding\ua0development\ua0with precise specifications post-development. Out of these 12 aspects, seven can likely be addressed as part of an ongoing agile transformation. We offer an empirical account of expectations and needs for new\ua0requirements\ua0engineering approaches\ua0in\ua0the\ua0automotive\ua0domain, necessary to coordinate hundreds of collaborating organizations developing software-intensive and potentially safety-critical\ua0systems

Spatio-temporal evolution of intraplate strike-slip faulting: the Neogene-Quaternary Kuh-e-Faghan Fault, Central Iran

Central Iran provides an ideal region to study the long-term morphotectonic response to the nucleation and propagation of intraplate faulting. In this study, a multidisciplinary approach that integrates structural and stratigraphic field investigations with apatite (U+Th)/He (AHe) thermochronometry is used to reconstruct the spatio-temporal evolution of the Kuh-e-Faghan Fault (KFF) in northeastern Central Iran. The KFF is a narrow, ca. 80 km long, deformation zone that consists of three main broadly left stepping, E-W trending, dextral fault strands that cut through the Mesozoic-Paleozoic substratum and the Neogene-Quaternary sedimentary cover. The AHe thermochronometry results indicate that the intra-fault blocks along the KFF experienced two major episodes of fault-related exhumation at ~18 Ma and ~4 Ma. The ~18 Ma faulting/exhumation episode is chiefly recorded by the structure and depositional architecture of the Neogene deposits along the KFF. A source-to-sink scenario can be reconstructed for this time frame, where topographic growth caused the synchronous erosion/exhumation of the pre-Neogene units and deposition of the eroded material in the surrounding fault-bounded continental depocenters. Successively, the KFF gradually entered a period of relative tectonic quiescence and, probably, of regional subsidence during which a thick pile of fine-grained onlapping sediments were deposited. This may have caused resetting of the He ages of apatite in the pre-Neogene and the basal Neogene successions. The ~4 Ma faulting episode caused the final exhumation of the fault system, resulting in the current fault zone and topography. The two fault-related exhumation episodes fit with the regional early Miocene collision-enhanced uplift/exhumation, and the late Miocene–early Pliocene widespread tectonic reorganization of the Iranian plateau. The reconstructed long term, spatially and temporally punctuated fault system evolution in intraplate Central Iran during Neogene-Quaternary times may reflect states of far-field stress changes at the collisional boundaries

The Extended Mind and Network-Enabled Cognition

In thinking about the transformative potential of network technologies with respect to human cognition, it is common to see network resources as playing a largely assistive or augmentative role. In this paper we propose a somewhat more radical vision. We suggest that the informational and technological elements of a network system can, at times, constitute part of the material supervenience base for a human agent’s mental states and processes. This thesis (called the thesis of network-enabled cognition) draws its inspiration from the notion of the extended mind that has been propounded in the philosophical and cognitive science literature. Our basic claim is that network systems can do more than just augment cognition; they can also constitute part of the physical machinery that makes mind and cognition mechanistically possible. In evaluating this hypothesis, we identify a number of issues that seem to undermine the extent to which contemporary network systems, most notably the World Wide Web, can legitimately feature as part of an environmentally-extended cognitive system. Specific problems include the reliability and resilience of network-enabled devices, the accessibility of online information content, and the extent to which network-derived information is treated in the same way as information retrieved from biological memory. We argue that these apparent shortfalls do not necessarily merit the wholesale rejection of the network-enabled cognition thesis; rather, they point to the limits of the current state-of-the-art and identify the targets of many ongoing research initiatives in the network and information sciences. In addition to highlighting the importance of current research and technology development efforts, the thesis of network-enabled cognition also suggests a number of areas for future research. These include the formation and maintenance of online trust relationships, the subjective assessment of information credibility and the long-term impact of network access on human psychological and cognitive functioning. The nascent discipline of web science is, we suggest, suitably placed to begin an exploration of these issues

Additive Manufacturing of a Vehicle Brake System Component

The present project aims to study the applicability of additive manufacturing (AM) in the automotive industry, namely, the applicability of AM in car parts production. A commercial vehicle can be described as a set of systems, all integrated and communicating each other, with a common goal, move you from point A to point B as secure as possible. The present study focused on the manufacture by AM of a part from one of the systems integrated in the vehicle, namely a brake calliper, component of the brake system. The Selective Laser Melting (SLM) was the AM process that was used to manufacture the part. It is important to understand that nowadays, a great level of evolution is occurring in the automotive industry. Some new technology had its origins in the racing world. Race teams lead by the big manufacturing car companies have the know-how and the opportunities to try and develop new technologies. This leads to a development in manufacturing processes associated with new components and materials. After some perfecting, the components and manufacturing techniques used in the racing industry find its way into the commercial vehicle market, leading to the endless flow of innovation that we see nowadays. The component selected to be developed and furthermore manufactured using AM was a brake calliper, part of the braking system of a racing vehicle. The new SLM produced brake callipers will be used in the Formula Student racing platform

Impact of Pore Size on Gas Condensate Critical Properties Confined in Marcellus Shale

Gas condensate reservoirs have become an important topic of research for reservoir engineers due to the drop in gas prices in the past few years. Because of this drop, the majority of gas producers have become more interested in condensate and wet gas resources. However, gas condensate reservoirs have a unique phase behavior system and they are considered the most complicated reservoirs to develop due to the continuous composition changes. Therefore, the effects of nanopores on the critical properties of the confined gas condensate in the Marcellus Shale will be investigated in this research in order to achieve the optimum gas and condensate production and to improve reservoir management plans for this kind of reservoir.;In this study, the given fluid data were used to construct a fluid model, which was then history matched with the given experimental measurements. The shift in the critical properties of gas condensate due to the pore confinement within the reservoir was calculated based on different pore sizes of 2 nm, 4 nm, and 5 nm. Then, a phase behavior and reservoir fluid program was used to build four fluid models, three models for the confinement case and a fourth model which represents the unconfined case, by the use of Peng-Robinson equation of the state (EOS). Next, four reservoir models were constructed by using a compositional and an unconventional reservoir simulator based on the obtained fluid models, from the phase behavior & reservoir fluid program, and the geological data of the Marcellus Shale. Finally, after constructing the reservoir models, many simulation runs were carried out in order to study the impact of the pore confinement on the gas phase behavior and gas condensate reservoir\u27s performance.;This research provides an insight and an explanation regarding how to optimize the gas and condensate production and maximize the economic revenue of the unconventional resources. It was concluded that producing more condensate and sustaining high gas production rate for a longer time can be achieved through producing the hydrocarbon from the confined formation with a nanopore size around 2 nm. The pore size of 2 nm can retard the pressure drop throughout the reservoir and result in sustaining the reservoir pressure higher than the dew point pressure. However, the confinement cases of pore size of 4 nm and 5 nm were found to have a negative effect on the gas and condensate production