Covid19 has spread globally. when the Covid-19 pandemic occurs, schools must be closed or partially opened, which affects teaching and learning. Educational innovations to deal with epidemics such as Covid-19 and other urgent epidemics are very important.Because some areas of mathematics are still incomplete today, this makes current technical tools such as online calculators Wolfram Alfa and Symbolab unable to direct solve certain Solution of triangle problems. This book also pres...

Quarantine for all asymptomatic strategy is incorrect in most high infection Covid-19 countries. Covid-19 surges in Italy (2020) and Taiwan (June 2022) are repeating the same mistakes made in Wuhan (China). This strategy will accumulate more asymptomatic high viral load super-spreaders and cause longer period of high infection. However, China's strict zero-coronavirus strategy is difficult to replicate in other high-infection Omicron countries because it is a costly strategy. Peter Chew's ...

The new covid-19 mutants usually have a higher transmission rate, the maximum positive rate must be lower to ensure that the undetected virus covid-19 carriers are low and the country is controlled. Different countries may face high infection with different covid-19 mutants, Therefore, each country must have a specific maximum positive rate based on its country’s covid-19 mutant. This study will create a general formula to determine the maximum positive rate for each country based on its c...

This book uniquely combines the authors’ personal experiences, deep cultural and professional experience of living and working in Russia and the former USSR, and interest and experience with language and computational analysis, to shed light on a highly contemporary question: what is motivating conflict and unrest in Russia and its surrounding countries? How does Russian government suppression of information manifest in practice today, and how does it fit into the historical cultural patte...

Makers around the globe are building low-cost devices to monitor the environment, and with this hands-on guide, so can you. Through succinct tutorials, illustrations, and clear step-by-step instructions, you’ll learn how to create gadgets for examining the quality of our atmosphere, using Arduino and several inexpensive sensors.Detect harmful gases, dust particles such as smoke and smog, and upper atmospheric haze—substances and conditions that are often invisible to your senses. Y...

**WINNER OF THE 2026 PULITZER PRIZE FOR OPINION WRITINGWINNER OF THE 2017 NATIONAL BOOK AWARD IN NONFICTIONWINNER OF THE NEW YORK PUBLIC LIBRARY'S HELEN BERNSTEIN BOOK AWARD**The essential journalist and bestselling biographer of Vladimir Putin reveals how, in the space of a generation, Russia surrendered to a more virulent and invincible new strain of autocracy.Award-winning journalist Masha Gessen's understanding of the events and forces t...

This book gives the basics of radio and how it is used. If you are interested in learning more about radio and radio communications this manual would be a good starting point for learning about it.

Fiona Hill and other U.S. public servants have been recognized as Guardians of the Year in TIME's 2019 Person of the Year issue.From the KGB to the Kremlin: a multidimensional portrait of the man at war with the West.Where do Vladimir Putin's ideas come from? How does he look at the outside world? What does he want, and how far is he willing to go?The great lesson of the outbreak of World War I in 1914 was the danger of misreading the statements, actio...

**From renowned foreign policy expert Angela Stent comes a dissection of how Putin created a paranoid and polarized world—and increased Russia's status on the global stage."Putin's World is the definitive guide to understanding the tangled history of post-Cold War Russia and its place in the world. Angela Stent offers a thoughtful, sober, and elegantly-written perspective that could not be more timely." —US Ambassador William J. Burns**How did Russia manage to emer...

What stands between you, the amateur radio operator, and all the other amateur radio operators in the world?Antennas. Yours, theirs…and propagation conditions between.In other words, you can have the most advanced transceiver, coupled with the most powerful amplifier on the market, if you know too little about how antenna systems work and about radio wave propagation, you risk spending your time and money for naught.This e-book is the first of a ser...

What additional challenge is there to HF communications besides:Overcoming often adverse propagation conditions;Establishing solid contacts in the cacophony of pileups when conditions are good;Acquiring the necessary operating skills?Finding space to install a large HF antenna, that's what!This e-book, with its many illustrations, will supply some of the most viable HF antenna solutions for restricted spaces, and exp...

Piping and Pipeline Calculations Manual is a "no nonsense" guide to the principle intentions of the codes or standards and provides advice on compliance. After using this book the reader should come away with a clear understanding of how piping systems fail and what the code requires the designer, manufacturer, fabricator, supplier, erector, examiner, inspector, and owner to do to prevent such failures. The focus of the book is to enhance participants' understanding and application of the ...