Complex adaptive systems Miller, John H; Miller, John H; Page, Scott E
2009., 20091128, 2009, 2007, 2007-01-01, 20070101, Letnik:
14
eBook
This book provides the first clear, comprehensive, and accessible account of complex adaptive social systems, by two of the field's leading authorities. Such systems--whether political parties, stock ...markets, or ant colonies--present some of the most intriguing theoretical and practical challenges confronting the social sciences. Engagingly written, and balancing technical detail with intuitive explanations,Complex Adaptive Systemsfocuses on the key tools and ideas that have emerged in the field since the mid-1990s, as well as the techniques needed to investigate such systems. It provides a detailed introduction to concepts such as emergence, self-organized criticality, automata, networks, diversity, adaptation, and feedback. It also demonstrates how complex adaptive systems can be explored using methods ranging from mathematics to computational models of adaptive agents.
John Miller and Scott Page show how to combine ideas from economics, political science, biology, physics, and computer science to illuminate topics in organization, adaptation, decentralization, and robustness. They also demonstrate how the usual extremes used in modeling can be fruitfully transcended.
Electrochemical capacitor (EC) applications have broadened tremendously since EC energy storage devices were introduced in 1978. Then typical applications operated below 10 V at power levels below ...1 W. Today many EC applications operate at voltages approaching 1000 V at power levels above 100 kW. This paper briefly reviews EC energy storage technology, shows representative applications using EC storage, and describes engineering approaches to design EC storage systems. Comparisons are made among storage systems designed to meet the same application power requirement but using different commercial electrochemical capacitor products.
•Electrochemical capacitors are used today in a broad range of applications.•Approaches presented for the design of capacitor storage systems.•No single commercial product offers superior performance in all applications.
Valuing Reversible Energy Storage Miller, John R.
Science (American Association for the Advancement of Science),
03/2012, Letnik:
335, Številka:
6074
Journal Article
Recenzirano
A process based on laser-converted graphene is used to fabricate high-value energy storage material.
The development of new materials that provide the capability of high-performance energy storage ...combined with flexibility of fabrication opens up the possibility of a wide range of technological applications. On page 1326 of this issue, El-Kady
et al.
(
1
) describe thin and highly flexible electrochemical capacitors (ECs) that were created by means of a very simple and innovative process. Unlike the usual approaches of making thin graphene electrodes that start with a particulate and use roll-coating, screen printing, or ink-jet printing (
2
), their process involves focusing a low-power laser onto a thin graphene oxide deposit to convert it into graphene. The incorporation of graphene in electrodes created with mechanical processes tends to be in agglomerates that provide little performance advantage over traditional particulate-activated carbon electrodes. El-Kady
et al.
's approach also contrasts with plasma-assisted chemical vapor deposition processes that have been used to grow vertically oriented graphene nanosheet electrodes (
3
). Although graphene structures grown by such methods are well-formed and offer performance advantages over traditional activated carbon materials, they require complicated vacuum process equipment, plus the graphene growth rate is very slow (
4
). The somewhat simple EC electrode fabrication process reported by El-Kady
et al.
therefore appears to circumvent many of the difficulties encountered with traditional processes.
•Electrochemical capacitors provide highly-reversible energy storage.•Specialized meetings held to advance electrochemical capacitor technology.•Perspective view presented on electrochemical ...capacitor technology.
Electrochemical capacitors, a type of capacitor also known by the product names Supercapacitor or Ultracapacitor, can provide short-term energy storage in a wide range of applications. These capacitors are powerful, have extremely high cycle life, store energy efficiently, and operate with unexcelled reliability. This article discusses highly-reversible energy storage, presents electrochemical capacitor basics, and identifies several resources that may be useful to a researcher who wishes to participate in this technology arena. A perspective on the future of electrochemical capacitor technology is offered.
Management of patients with femoroacetabular impingement and moderate (Tönnis grade 2) osteoarthritis remains a debated topic. Outcomes show that such patients can benefit from hip arthroscopy, yet ...the improvement may not be as favorable as desired. Although certain factors, such as Tönnis grade 3 hip OA, older age, higher body mass index, bipolar cartilage defects, and joint space less than 2 mm, may influence surgeons to avoid arthroscopic treatment, the threshold for grade 2 OA is not as clear. Moreover, although radiographs may appear similar in patients with Tönnis grade 2, there may be a wide range of chondral damage seen arthroscopically. Thus, until higher-level studies are performed, it is the responsibility of the surgeon to delineate appropriate treatment strategies for individual patients in this category, and most of all, it is crucial for surgeons to set reasonable expectations for patients when considering hip arthroscopy. This highlights the importance of careful preoperative evaluation and patient education.
The advent of optical coherence tomography (OCT) revolutionized both clinical assessment and research of vitreoretinal conditions. Since then, extraordinary advances have been made in this imaging ...technology, including the relatively recent development of swept-source OCT (SS-OCT). SS-OCT enables a fast scan rate and utilizes a tunable swept laser, thus enabling the incorporation of longer wavelengths than conventional spectral-domain devices. These features enable imaging of larger areas with reduced motion artifact, and a better visualization of the choroidal vasculature, respectively. Building on the principles of OCT, swept-source OCT has also been applied to OCT angiography (SS-OCTA), thus enabling a non-invasive in depth-resolved imaging of the retinal and choroidal microvasculature. Despite their advantages, the widespread use of SS-OCT and SS-OCTA remains relatively limited.
In this review, we summarize the technical details, advantages and limitations of SS-OCT and SS-OCTA, with a particular emphasis on their relevance for the study of retinal conditions. Additionally, we comprehensively review relevant studies performed to date to the study of retinal health and disease, and highlight current gaps in knowledge and opportunities to take advantage of swept source technology to improve our current understanding of many medical and surgical chorioretinal conditions. We anticipate that SS-OCT and SS-OCTA will continue to evolve rapidly, contributing to a paradigm shift to more widespread adoption of new imaging technology to clinical practice.
•Swept source (SS) OCT/OCTA provide high speed and deep resolution.•These features allow simultaneous imaging of the vitreous, retina and choroid.•We critically reviewed SS-OCT/SS-OCTA applications to studying vitreoretinal conditions.•Wider use of SS-OCT/OCTA can increase the current understanding of retinal diseases.
Additive manufacturing (AM) has rapidly emerged as a disruptive technology to build mechanical parts, enabling increased design complexity, low-cost customization and an ever-increasing range of ...materials. Yet these capabilities have also created an immense challenge in optimizing the large number of process parameters in order achieve a high-performance part. This is especially true for AM of soft, deformable materials and for liquid-like resins that require experimental printing methods. Here, we developed an expert-guided optimization (EGO) strategy to provide structure in exploring and improving the 3D printing of liquid polydimethylsiloxane (PDMS) elastomer resin. EGO uses three steps, starting first with expert screening to select the parameter space, factors, and factor levels. Second is a hill-climbing algorithm to search the parameter space defined by the expert for the best set of parameters. Third is expert decision making to try new factors or a new parameter space to improve on the best current solution. We applied the algorithm to two calibration objects, a hollow cylinder and a five-sided hollow cube that were evaluated based on a multi-factor scoring system. The optimum print settings were then used to print complex PDMS and epoxy 3D objects, including a twisted vase, water drop, toe, and ear, at a level of detail and fidelity previously not obtained.
High-latitude ecosystems have the capacity to release large amounts of carbon dioxide (CO₂) to the atmosphere in response to increasing temperatures, representing a potentially significant positive ...feedback within the climate system. Here, we combine aircraft and tower observations of atmospheric CO₂ with remote sensing data and meteorological products to derive temporally and spatially resolved year-round CO₂ fluxes across Alaska during 2012–2014. We find that tundra ecosystems were a net source of CO₂ to the atmosphere annually, with especially high rates of respiration during early winter (October through December). Long-term records at Barrow, AK, suggest that CO₂ emission rates from North Slope tundra have increased during the October through December period by 73% ± 11% since 1975, and are correlated with rising summer temperatures. Together, these results imply increasing early winter respiration and net annual emission of CO₂ in Alaska, in response to climate warming. Our results provide evidence that the decadal-scale increase in the amplitude of the CO₂ seasonal cycle may be linked with increasing biogenic emissions in the Arctic, following the growing season. Early winter respiration was not well simulated by the Earth System Models used to forecast future carbon fluxes in recent climate assessments. Therefore, these assessments may underestimate the carbon release from Arctic soils in response to a warming climate.
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