【推荐3】Musical instruments range from simple to complex. They differ from one part of the world to another. But all instruments produce sound the same way, by means of vibrations (rapid back-and-forth movements). These vibrations reach our ears as sound waves.    1     Vibrations come from striking, plucking (弹或拨), and blowing on instruments, or by moving a bow across them. Faster vibrations produce higher notes.

Instruments we strike

    2     When we shake a rattle, objects inside it strike the rattle’s wall and make a sound. Instruments that make sounds by striking them have been used since the Stone Age. Striking the instrument starts the vibrations.

    3     This kind of instrument is a drum. The stretched membrane vibrates to produce the sound. Drums are found in nearly every culture around the world.

Instruments with strings

Some musical instruments, such as violins and harps, have strings that vibrate. Stretching the strings by plucking or striking makes them vibrate. Violins, violas, and cellos are played by drawing a bow across their strings. The guitar, lute, banjo, and harp have strings that are plucked with the fingers.     4     Pressing a key on the keyboard causes a string to be hit with a small hammer.

    5    

Flutes, trumpets, saxophones, and other instruments produce sound through vibrations of air. A flute sounds when we breathe air into a hole on its side or its end. By covering finger holes on the flute, we can change the pitch of the notes—how high or low the notes are.

【推荐1】The hydrogen-powered drone(无人机)，called “Qingting” in Chinese pronounced the same as the Chinese word “dragonfly”,has completed the automatic inspection of the 500 kilovolt of Wangnan Line.

It is the first time that a fuel-cell drone powered by hydrogen has been used in the national electrical power system to carry out inspection programs, meaning that hydrogen energy equipment has been firstly applied into the inspection of power grid(网).

The inspection drone traditionally is powered by lithium batteries which can last 20-30 minutes on average.There exists a certain threat to inspection safety if the drone falls out of control due to its use of large-capacity lithium battery pack, which easily leads to burn and explode. Thus, the current urgent need of inspection work for power grid requires a new kind of drone with long battery life,continuous inspection,and high security.

It is introduced that, this year State Grid Wenzhou Power Supply Company,together with Jinling Carbon Energy Digital Intelligence Technology Laboratory, finally successfully invented the first hydrogen-powered drone after half a year’s exploration and perseverance. As an electric drone taking hydrogen fuel cell to generate the power and hydrogen,hydrogen does not burn in thefuel cell during the operation of “Qingting”. Instead,it can be transformed directly into electricity by combining hydrogen and oxygen through the action of platinum-carbon catalyst in a clean and carbon-free way, and the only product is water.

It is learned that it offers power autonomy of 2 hours, about four times that of the lithium battery drone. The life of hydrogen fuel cell is more than 2000 hours,about 20 times that of the lithium battery.The battery of hydrogen fuel cell contains no heavy metal pollutants, whose materials can be recycled after destruction. It is tested that the “Qingting”drone fails to burn or explode when it falls out of control,which performs better in safety.

The success of the initial inspection of the“Qingting”drone has filled the gap of the application of hydrogen fuel in the electric power drone. Next, the company will expand the multi-directional application of hydrogen drones in inspection for power grid by carrying different functional equipment to make breakthroughs in the technical barriers. Moreover, under the national policy of actively promoting the application of clean energy, accelerating the development of hydrogen fuel cells in the field of unmanned aviation vehicles(UAVs)is of significance.

【推荐2】MUSICAL HERITAGES FROM ANCIENT CHINA

Since remote antiquity, Chinese people have used music to record their lives and describe the ideals in their hearts. Catchy tunes are not only played on precious instruments, but also visualized in carvings, paintings, and buildings. Feel free to explore here!

Han Dynasty (202 BC-AD 220)

This period marked the significant development of the manufacturing of gugin and its music. The example unearthed from the Mawangdui Han Dynasty Tomb in Changsha, Hunan province, proves that gugin had developed into the form known today during that period. It shows 7 strings and 13 markers indicating the pressing positions of overtone series.

Northern Wei Dynasty (386-534)

Buddhism and its musical culture spread extensively during this period. Buddhist temples provided places for musical activities, which were recorded in many of the existing stone carvings. Located in Gongyi, Henan province, the Grotlo Temple is famous for its reliefs representing musical events. They are precious historical materials reflecting the music characteristics of the dynasty.

Song Dynasty (960-1279)

With economic development, a variety of musical cultures emerged to meet the entertainment needs of different social classes. Part of the painting Life along the Bian River al the Pure Brightness Festival vividly reveals a storytelling performance. The painter adopted delicate techniques to truly record a street performer, whose superb skills are reflected by each listener’s show of appreciation.

Ming Dynasty (1368-1644)

At this time, traditional Chinese operas developed rapidly, promoting the formation of many singing styles. People began to enjoy operas and drama stages were built. Covering a construction area of more than 160 square meters, the Fancun village drama stage in Shanxi province provides rich materials for the study of the local folk culture.

【推荐3】Along the rocky Algerian coast, just east of where Mount Chenoua slides into the Medi-terranean, has stood Tipasa for more than 2,500 years. It is considered one of the most important archaeological sites in North Africa.

Tipasa fell into ruin in the sixth century. Both its main group of buildings on the coast and an inland monumental tomb(陵墓)surrounded by the olive trees were all forgotten. Most of the ancient city, in fact, remains buried under the ground. For the last few decades, however, what’s left of Tipasa’s past has been increasingly surrounded on three sides by the expanding modern town of Tipasa. And to the north, the waves lap ever closer.

“What’s special about Tipasa, a UNESCO-designated World Heritage Site since 1982, is its unique landscape, the shared presence of history and archaeology, culture, nature and architecture. It’s the spirit of the place,” said Lynda, who has studied Tipasa and the ongoing challenges from both rapid urbanization(城市化)and inadequate(不足的)site management.

Now, Tipasa is entering a new period, perhaps its last: It’s become a symbol of an entire continent’s heritage in great danger. In a recent Nature Climate Change paper, a team reported the results: How sea level rise is affecting nearly 300 World Heritage Sites around Africa’s roughly 20,000 miles of coastline. About 20 percent of the sites examined, including Tipasa, are already at high risk from flooding and erosion(侵蚀).By 2050 that figure is expected to more than three times.

The site’s 21st-century problems have only increased in the last two decades. UNESCO has repeatedly threatened to strip the site of World Heritage status. As recently as 2021, the organization noted a series of problems at Tipasa, such as modern building, including a proposed port, that threatened the site’s completeness.