The last two decades have witnessed several advances in microfabrication technologies and electronics, leading to the development of small, low-power devices for wireless sensing, data transmission, actuation, and medical implants. Unfortunately, the actual implementation of such devices in their respective environment has been hindered by the lack of scalable energy sources that are necessary to power and maintain them. Batteries, which remain the most commonly used power sources, have not kept pace with the demands of these devices, especially in terms of energy density. In light of this challenge, the concept of vibratory energy harvesting has flourished in recent years as a possible alternative to provide a continuous power supply. While linear vibratory energy harvesters have received the majority of the literature’s attention, a significant body of the current research activity is focused on the concept of purposeful inclusion of nonlinearities for broadband transduction. When compared to their linear resonant counterparts, nonlinear energy harvesters have a wider steady-state frequency bandwidth, leading to a common belief that they can be utilized to improve performance in ambient environments. Through a review of the open literature, this paper highlights the role of nonlinearities in the transduction of energy harvesters under different types of excitations and investigates the conditions, in terms of excitation nature and potential shape, under which such nonlinearities can be beneficial for energy harvesting. [DOI: 10.1115/1.4026278]

On the Role of Nonlinearities in Vibratory Energy Harvesting: A Critical Review and Discussion

In gripping accounts of true cases, surgeon Atul Gawande explores the power and the limits of medicine, offering an unflinching view from the scalpel's edge. Complications lays bare a science not in its idealized form but as it actually is--uncertain, perplexing, and profoundly human. "Complications "is a 2002 National Book Award Finalist for Nonfiction.

Complications: A Surgeon's Notes on an Imperfect Science

The ongoing emission of greenhouse gases (GHGs) is triggering changes in many climate hazards that can impact humanity. We found traceable evidence for 467 pathways by which human health, water, food, economy, infrastructure and security have been recently impacted by climate hazards such as warming, heatwaves, precipitation, drought, floods, fires, storms, sea-level rise and changes in natural land cover and ocean chemistry. By 2100, the world’s population will be exposed concurrently to the equivalent of the largest magnitude in one of these hazards if emmisions are aggressively reduced, or three if they are not, with some tropical coastal areas facing up to six simultaneous hazards. These findings highlight the fact that GHG emissions pose a broad threat to humanity by intensifying multiple hazards to which humanity is vulnerable.

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Broad threat to humanity from cumulative climate hazards intensified by greenhouse gas emissions

Fuzzy ahp approach for selecting the suitable bridge construction method

A review of risk management through BIM and BIM-related technologies

Over 500 failures of bridge structures in the United States between 1989 and 2000 were studied. The age of the failed bridges ranged from 1 year (during construction) to 157 years, with an average of 52.5 years. The most frequent causes of bridge failures were attributed to floods and collisions. Flood and scour, with the major flood disaster in 1993, contributed to the frequency peak of bridge failures (almost 53% of all failures). Bridge overload and lateral impact forces from trucks, barges/ships, and trains constitute 20% of the total bridge failures. Other frequent principal causes are design, detailing, construction, material, and maintenance. Comparison made among three periods of similar studies (1977–1981, 1982–1988, and 1989–2000) revealed almost similar trends, with most failures occurring during the bridge’s service life. Also, human-induced external events occurred frequently in all three periods, but were most dominant in the first and third periods. Technological advances in information sys...

Analysis of recent bridge failures in the united states

A total of 225 building failures in the United States from 1989 to 2000 were recorded in this study. The result shows that failures of low-rise buildings constitute about 63% of all cases, followed by multistory buildings as a distant second. In terms of their functions, apartments are the most frequent to fail. External events and construction and maintenance deficiencies have been identified as the most frequent principal causes. External events include rain, wind, snow, vehicular impact, and collision. Construction deficiencies encompass improper renovation, unplanned demolition, poor workmanship, and unsafe excavation operations. Maintenance deficiencies are associated with building deterioration that was overlooked and improperly maintained. A comparative analysis conducted between this study and two previous studies indicates an inclined trend of relative failure occurrences of low-rise and multistory buildings. The study also suggests that, despite the recent enhancement of information technology, current sources of information are still incomplete. The creation of new complete databases, further improvement of information sources, and their dissemination through the Internet are deemed essential to prevent building failures from recurring.

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Kumalasari Wardhana

Papers

Analysis of recent bridge failures in the united states

Study of recent building failures in the United States

Closure of "Study of Recent Building Failures in the United States"