Grid converters are the key player in renewable energy integration. The high penetration of renewable energy systems is calling for new more stringent grid requirements. As a consequence, the grid ...converters should be able to exhibit advanced functions like: dynamic control of active and reactive power, operation within a wide range of voltage and frequency, voltage ride-through capability, reactive current injection during faults, grid services support.This book explains the topologies, modulation and control of grid converters for both photovoltaic and wind power applications. In addition to power electronics, this book focuses on the specific applications in photovoltaic wind power systems where grid condition is an essential factor.With a review of the most recent grid requirements for photovoltaic and wind power systems, the book discusses these other relevant issues:modern grid inverter topologies for photovoltaic and wind turbines islanding detection methods for photovoltaic systems synchronization techniques based on second order generalized integrators (SOGI) advanced synchronization techniques with robust operation under grid unbalance condition grid filter design and active damping techniques power control under grid fault conditions, considering both positive and negative sequences Grid Converters for Photovoltaic and Wind Power Systemsis intended as a coursebook for graduated students with a background in electrical engineering and also for professionals in the evolving renewable energy industry. For people from academia interested in adopting the course, a set of slides is available for download from the website. www.wiley.com/go/grid_converters
Written by an antenna engineer turned professor who has worked at Apple, Nokia and Amphenol,<i>Antenna Design for Mobile Devices</i>is a comprehensive guide for fresh and intermediate ...engineers involved in antenna design. The book instructs readers through all aspects of real world antenna designs, which includes how to make a stable antenna fixture, designing various types of antennas, designing an antenna with good manufacturability, using various matching technique to improve antenna performance, setting up production measurement for mass manufacturing, and making antenna SAR and HAC compliant. Most popular antenna categories, such as internal PIFA, integral IFA, internal folded monopole, ceramic antennas, stubby antennas and whip stubby antennas, are introduced in the book. The book focuses on the basic principle of each kind of antenna and emphasizes on key parameters of antenna optimization. Complimentary matching software, which accompanies the book, is provided so readers can practice various antenna matching technique and design matching circuits for real projects. <ul> <li>A one-stop design reference containing all an engineer needs when designing antennas</li> <li>Accessible to readers of many levels, from introductory to specialist</li> <li>Presents shortcuts for engineers who lack antenna knowledge but need no-hassle techniques for designing simple antennas</li> <li>Contains hands-on knowledge not available in other books</li> <li>Written by a practicing expert who has hired and trained numerous engineers</li> <li>Incorporates the various techniques used by pure-play antenna firms, established mobile device brands, and new entrants to the mobile space</li> <li>Comes with antenna matching software written by the author, which can be used for practice and real-world projects</li> <li>Presentation slides with lecture notes available for instructor use</li> </ul> <p>This book is targeted at practicing antenna engineers, particularly those focusing on mobile devices, as well as researchers and academics looking to keep up with this quick-changing field. Engineering managers will find it to be a helpful guide for teaching new hires, while new hires, by using the book themselves, will be able to quickly gain expert-level proficiencies. The book is also suitable for wireless network equipment engineers, who desire a stronger sense of antenna principles, as well as electronic engineering students studying electromagnetics. Readers should possess a basic undergraduate-level understanding of electromagnetic theory.<br /> Companion website for the book:<br /> <a href="http://www.wiley.com/go/zhangantenna">http://www.wiley.com/go/zhangantenna</a></p>
AimNeonatal infections carry a heavy burden of morbidity and mortality. Poor practice can result in unintentional colonisation of medical equipment with potentially pathogenic organisms. This study ...will determine the prevalence and type of bacterial contamination on exposed neonatal resuscitation equipment in different clinical settings and explore simple measures to reduce contamination risk.MethodsA survey determined the rates of resuscitation equipment usage. All environmentally-exposed items were identified on resuscitaires hospital-wide and swabbed for bacterial contamination. A new cleaning and storage policy was implemented and the prevalence of environmentally-exposed equipment re-measured post-intervention.ResultsResuscitation equipment was used in 28% of neonatal deliveries. Bacterial colony forming units were present on 44% of the 236 exposed equipment pieces swabbed. There was no significant difference in contamination rates between equipment types. Coagulase negative staphylococcus was the most prevalent species (59 pieces, 25%) followed by Escherichia coli and Enterobacter cloacae (20 pieces, 9% each). Opened items stored inside plastic remained sterile, whilst those in low-use areas had significantly less contamination than those in high-use areas (22% vs 51%, P < 0.05). Implementing a simple educational program led to a significant reduction in environmentally-exposed equipment (79% reduction, P < 0.01).ConclusionsPathogenic bacteria can colonise commonly used pieces of neonatal resuscitation equipment. Whilst the clinical significance remains uncertain, equipment should be kept packaged until required and discarded once open, even if unused. Standardising cleaning policies result in rapid and significant improvements in equipment storage conditions, reducing microbial colonisation opportunities.
Thoroughly revised, this book provides the reader with an understanding of the principles and practices of testing and balancing (TAB) heating, ventilating, and air conditioning (HVAC) air and water ...systems. For the novice and the experienced testing and balancing technician, it is a field reference book of procedures, equations, and information tables.
Divided into five parts, Part I has general and specific balancing procedures for constant air volume systems, variable air volume systems, return air systems, and fans and fan performance. Part II covers testing and balancing fume hood systems and cleanrooms, commissioning HVAC systems, centrifugal pumps and pump performance, analog and digital controls and water balancing procedures using flow meters, system components, and temperatures. Part III covers fans, pumps, air distribution, water distribution, motors, electrical, fluid flow, psychrometrics, refrigeration, and instrument usage and care. Part IV includes equations and tables. New to this edition, Part V has information and additional test and balance procedures and graphics for chapters 1-7 and 13-14. TAB Data and Test forms are in the new addendum as well.
Provides the readers with revised information about the principles and practices of testing and balancing (TAB) heating
Represents a field reference guide for both the novice and experienced testing and balancing technician
Includes a new section with information and additional test and balance procedures and graphics
Dangers of disposable electronic devices Young, Laura; Dawson, Sue; Lavallee, David ...
Science (American Association for the Advancement of Science),
04/2024, Letnik:
384, Številka:
6694
Journal Article
Widespread shortages of personal protective equipment (PPE) during the COVID-19 pandemic have placed health care workers at risk and threatened their ability to care for patients.1 Items in shortage ...include disposable filtering facepiece respirators ("N95 masks"), filter cartridges for powered airpurifying respirators, face shields, and surgical scrubs. Many of these shortages reflect fragile international supply chains based on just-in-time manufacturing and lean inventories. Ranney et al. recently identified several promising approaches to improving national coordination of PPE supply,2 but we believe that responses to health care emergencies must also be strengthened at the community level. This is a well-recognized concept in the setting of natural disasters,3 but to our knowledge the role of fabrication of medical products such as PPE by local companies and concerned citizens (including "maker" and 3D printing communities) has not been previously considered for disease pandemics. Local fabrication during the COVID-19 crisis has largely focused on face masks, respirators, and ventilator parts but could extend in future emergencies to stretchers, custom software, and transportation. For such solutions to be useful, they must be informed by regulatory and performance standards, and hospitals must have the data needed for adoption and deployment. Shifting regulatory guidance on PPE, the introduction of products from nontraditional suppliers, and an absence ofscientific data in many guidance documents have raised concerns among health care workers that evolving PPE standards may not be based on rigorous evidence.
The coronavirus disease 2019 (COVID-19) pandemic continues to devastate US nursing homes. Adequate personal protective equipment (PPE) and staffing levels are critical to protect nursing home ...residents and staff. Despite the importance of these basic measures, few national data are available concerning the state of nursing homes with respect to these resources. This article presents results from a new national database containing data from 98 percent of US nursing homes. We find that more than one in five nursing homes reports a severe shortage of PPE and any shortage of staff. Rates of both staff and PPE shortages did not meaningfully improve from May to July 2020. Facilities with COVID-19 cases among residents and staff, as well as those serving more Medicaid recipients and those with lower quality scores, were more likely to report shortages. Policies aimed at providing resources to obtain additional direct care staff and PPE for these vulnerable nursing homes, particularly in areas with rising community COVID-19 case rates, are needed to reduce the national COVID-19 death toll.
High profile device failures have highlighted the inadequacies of current regulation. Art Sedrakyan and colleagues call for a move to a graduated model of approval and suggest a framework to achieve ...this goal
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