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Photo courtesy of vision china

　　Our reporter Fu Lili

　　Recently, according to media reports, like most large retailers, Wal-Mart stores in the United States are planning to replace paper labels on shelves with small electronic screens, so that prices can be changed quickly and at low cost. But the conversion from paper to screen faces another problem — — The screen needs power. At present, Wal-Mart is cooperating with Osiya Company to adopt the technology of "long-distance charging", also known as "charging in the air" (Cota) to solve this problem.

　　Charging from a distance sounds amazing. What is its principle and how is it realized?

　　"Collecting" electromagnetic energy from space to realize charging

　　"Wal-Mart this ‘ Charging in the air ’ The principle of is not profound, it is ‘ Wireless charging ’ A specific application of technology. " Recently, Yan Huaizhi, director of the Institute of Computer Network and Countermeasure of Beijing Institute of Technology, said in an interview with a reporter from Science and Technology Daily.

　　Yan Huaizhi introduced that the so-called wireless charging refers to the wireless transmission technology of electric energy realized by non-physical contact.

　　The idea of wireless energy transmission has a long history. As early as more than 100 years ago, Tesla proposed the idea of realizing global wireless power supply through the atmospheric ionosphere.

　　The law of conservation and transformation of energy is universally applicable in nature, and electromagnetic space is no exception, which can be proved by Lenz’s law. The essence of Lenz’s law is that "the magnetic field of induced current always hinders the change of magnetic flux that causes induced current." When the magnetic flux in the coil increases, the direction of the induced current is opposite to that of the magnetic field generated by it, while when the magnetic flux in the coil decreases, the direction of the induced current is the same as that of the magnetic field generated by it. Because electromagnetic induction also follows the law of energy conservation and transformation, people can realize energy transformation and propagation through electromagnetic induction.

　　"Specifically, Wal-Mart’s charging method from a distance is that an electric energy transmitter provides an energy source and emits a certain frequency spectrum in a specific direction range, thus creating a three-dimensional electromagnetic energy space." Yan Huaizhi explained that electronic equipment in the space covered by the RF signal can receive the signal if it is equipped with a signal receiving device with the corresponding frequency spectrum, so as to realize electromagnetic induction with the transmitter, thus "collecting" the electromagnetic energy transmitted by the transmitter through the air from a distance and realizing wireless charging of the receiving electronic device.

　　Wei Zhiqing, an associate professor at the School of Information and Communication Engineering of Beijing University of Posts and Telecommunications, further explained that the working principle of Wal-Mart’s air charging equipment is similar to that of WiFi and Bluetooth, and it consists of a transmitter and multiple receivers. Hundreds of micro antennas are integrated in the transmitter, while the receiver is only the size of a coin and is installed on the equipment that needs charging. The receiver will send a request signal for charging to the transmitter when the power is low. After receiving the request signal, the transmitter will charge the equipment at a frequency of 100Hz per second. In the APP that controls charging, you can specify charging devices and charging strategies (for example, give priority to charging devices with low power), and you can charge up to 32 devices at the same time.

　　Yan Huaizhi said that the distance and charging time that people care about this kind of charging technology can reach mainly depends on two factors, one is the transmitting power of the wireless spectrum of the transmitting device, and the other is the transmitting frequency of the wireless spectrum.

　　According to reports, the laboratory prototype system of Wal-Mart’s air charging device is CotaTile, with the transmitting power of 20 watts, the receiving power of equipment at a distance of 1 meter is about 6 watts, and the receiving power of equipment at a distance of 2 meters is 2 to 3 watts, which can charge equipment at a distance of 10 meters at the farthest.

　　You can also see these wireless charging technologies.

　　In addition to this way of charging from a distance, there are many commonly used wireless charging methods.

　　Yan Huaizhi introduced that the first is electromagnetic induction technology wireless charging, also known as Qi standard wireless charging. At present, this method is mostly used for wireless charging of the latest models of Xiaomi, Huawei and Apple on the market. The user can put the mobile phone on the charging base to charge without charging cable.

　　Wei Zhiqing said that its working principle is that the wireless charging base and the mobile phone are respectively equipped with a transmitting coil and a receiving coil. By using electromagnetic induction, when they are close, the transmitting coil in the charging base is connected with alternating current to generate an alternating magnetic field, and the change of the magnetic field makes the receiving coil generate current, thus transferring energy from the transmitting end to the receiving end, that is, supplying power to the mobile phone from the charging base. The advantage of this method is that the charging efficiency is high, and the charging efficiency of smart phone can reach 80%. The disadvantage is that the charging distance is short, so it is usually necessary to put the phone close to the charging base.

　　Secondly, electromagnetic resonance wireless charging, which uses resonant devices to make the transmitter and receiver reach the same frequency, and the same resonant frequency is a necessary condition for energy transfer, and electromagnetic energy can be exchanged through magnetic resonance. Compared with electromagnetic induction, the advantage of this method is that there is no need to "cling". The charging distance of smart phones can reach 10 cm, but its charging efficiency is slightly lower, usually less than 70%.

　　In addition, there is wireless radio frequency technology, which uses space electric field as energy transmission medium and generates alternating current under the action of alternating electromagnetic field, thus realizing long-distance wireless transmission of electric energy. The advantage of this method is long charging distance, but the disadvantage is strong electromagnetic radiation and low conversion efficiency.

　　Although "wireless" is good, it faces many challenges.

　　"Compared with wired charging, the advantages of wireless charging are very unique, including the convenience of use, the security of transmission, the compactness of the device and the integration of the environment, but there are also many challenges, which are embodied in both technical and non-technical aspects." Yan Huaizhi said that technically, wireless charging involves technical problems such as wireless transmission of power signals, high-frequency conversion, coupling coil design, system collaborative control, electromagnetic shielding and electromagnetic interference. For example, although close-range RFID devices, smart phones, tablets, smart watches, hearing AIDS, etc., to long-distance drones and even spacecraft in space, they can be charged in the air. However, due to the principle of electromagnetic induction, any factors that damage or weaken the propagation of electromagnetic spectrum signals, such as electromagnetic shielding, insufficient power and unstable frequency, will have a fatal impact on it. On the non-technical level, there are problems such as high cost of wireless charging equipment, difficulty in unifying technical standards, and public doubts about electromagnetic radiation.

　　But he believes that these problems will be effectively solved with the further development of technology.

　　Wei Zhiqing added that the biggest problem of wireless charging is the low charging efficiency, which generally only supports 5W charging power, and the slightly faster charging power is only 7.5W. In addition, regarding the public’s concerns about the electromagnetic radiation that may be brought by wireless charging, it is necessary for enterprises and evaluation institutions to conduct rigorous experiments and extensive popularization of science, so as to dispel public concerns. Due to the wide charging range of wireless charging, it will have broad application prospects in the field of Internet of Things in the future.

△ The first cross-ocean mid-ridge ocean electromagnetic method joint detection profile in China

　　Recently, the research team of south china sea institute of oceanology cooperated with the researchers of China Geo University (Beijing) to conduct the first cross-ocean mid-ridge deep-sea artificial source electromagnetic and magnetotelluric joint detection profile experiment in China at the depth of about 4,000m in the central basin of the South China Sea through the electromagnetic transmitting and receiving equipment independently developed by China. The whole section is nearly 100 kilometers long, with 16 receiving measuring points, and good electromagnetic data are obtained. This experiment marks a further breakthrough in China’s high-power artificial source electromagnetic detection technology under complex deep-sea terrain conditions.

　　Marine electromagnetic method is an important method to detect the geological structure of the seabed. At present, a few units from the United States and Europe have mature technology and equipment to carry out joint detection of artificial sources and magnetotelluric methods in the deep sea. In the past 20 years, with the long-term unremitting efforts of researchers from many domestic units, China has made important progress in the fields of submarine electromagnetic field observation, high-power artificial source launch, electromagnetic offshore operation technology, data analysis and processing.

△ Combined detection equipment and schematic diagram of marine electromagnetic method

　　Sun Zhen, the person in charge of the project, said that all the electromagnetic transmitting and receiving equipment independently developed by Chinese scientists was used in this voyage. In order to carry out this experiment, the project team prepared for four years. Wang Meng, an associate professor at China Geo University (Beijing), said that this joint exploration has realized the long-term observation of multi-component natural source electromagnetic field in the deep seabed, and also successfully realized the launching operation of towed high-power artificial electromagnetic source near the seabed, which effectively supplemented the high-frequency natural source electromagnetic signal absorbed by the extremely thick highly conductive seawater layer.

　　The joint exploration of ocean electromagnetic method across the mid-ocean ridge was carried out by the south china sea institute of oceanology Comprehensive Geophysical Research Ship "Experiment 6". This exploration has achieved the goal of simultaneously detecting the resistivity structure of shallow crust and deep mantle with one geophysical profile, which will significantly enhance China’s ability to detect seabed geological structure and resources by using ocean electromagnetic method.

　　(Headquarters CCTV reporter Shuai Junquan Chuerjia)

The replacement of new energy sources with electricity is actually nothing new.

In 1896, Hartford Electric Light Company, born in Hartford, Connecticut, USA, introduced an electric van with replaceable batteries. The buyer only bought the vehicle, but did not include the battery, and then paid the charging and maintenance fee by mileage when using it.

The specific business model is that vehicles are sold to users by GeVeCo (a subsidiary of General Electric), and HELCO is responsible for holding and providing battery packs to consumers. As for users, they buy HELCO’s power exchange service in the form of monthly fee. From 1910 to 1924, HELCO’s power exchange service provided electric trucks with a cruising range of more than 6 million miles.

Nowadays, looking at the power exchange technology of new energy vehicles is more like a "technical revival" that lasted for nearly a hundred years. In the field of commercial vehicles, there are State Grid, Yutong Bus, Beiqi New Energy and other enterprises, while in the field of passenger cars, there are Weilai.

Today, most new energy vehicles have not yet achieved "separation of vehicles and electricity". In 2017, the technology of power exchange was explored, and the first power exchange station was put into operation in 2018. In more than six years, Weilai has built 2,435 power exchange stations nationwide. In these six years, many car companies only chose to follow up on a small number of models.

Even so, Weilai iterated the power station changing technology to the fourth generation. The fourth generation power station, which was officially launched in Guangzhou not long ago, comes standard with six ultra-wide-angle laser radars and four Orin X chips, and supports one-button automatic power exchange and independent power exchange when leaving the vehicle.

Compared with the previous generation, the speed of power exchange is increased by 22%, the fastest time is only 2 minutes and 24 seconds, the number of battery positions is increased to 23, and the maximum number of daily services can reach 480 times.

Moreover, the new power exchange station can also support multi-brand sharing power exchange, including Ledao, which makes many people daydream about the power exchange of more models.

However, in order to make more models have the ability to exchange electricity, it is necessary to build a large enough stage to introduce other car companies and ecological partners.

On November 21, 2023, Changan Automobile announced that it had reached a cooperation with Weilai, and the two sides would jointly research and develop battery-changing vehicles, battery-changing technologies and unified standards. Weilai’s battery-changing camp was expanded for the first time.

However, people’s real re-examination of this alliance may have originated from the dialogue between Li Bin and He Xiaopeng in early May this year. At that time, He Xiaopeng personally visited Li Bin and said that when Weilai replaced more than 5,000 power stations, he would consider joining the power exchange mode.

Soon after, FAW announced that it had reached a strategic cooperation with Weilai for charging and replacing electricity.

Today, the power exchange alliance has seven car partners, including Changan, Geely, Chery, Jianghuai, FAW, GAC and Lotus, as well as energy and power enterprises such as "Three Barrels of Oil", Shell, State Grid, China Southern Power Grid, Wanneng Group, Zhongan Energy, Contemporary Amperex Technology Co., Limited, Zhongchuang Singapore Airlines and Longji Green Energy, with considerable influence.

However, Yang Chao, assistant vice president of Weilai and head of energy product development, told Leifeng. com "New Smart Drive" more than once that Weilai hopes to realize the scale of power exchange infrastructure and share the power exchange mode with the whole China automobile industry, hoping that more brands will join the TV exchange family, so that more users can enjoy the more convenient experience of adding power than refueling.

The efficiency of energy supplement has always been an important factor for consumers to buy new energy vehicles. From the market feedback, the sales growth rate of plug-in hybrid extended-range new energy vehicles has also obviously accelerated.

According to the statistics of the Association, the sales volume of hybrid (including extended range) new energy vehicles in May this year was 308,773, a year-on-year growth rate of 61.1%; The sales volume of pure electric new energy vehicles was 495,825, with a year-on-year growth rate of 27.6%.

In Yang Chao’s view,The reason for the slowdown in the sales of pure electric vehicles is the fuel tank (energy replenishment efficiency).However, there are different technical paths for pure electric vehicles to improve the charging efficiency, such as overcharge +CTB(Cell To Body), battery replacement and so on.

The reason why Weilai set up a power exchange alliance and cooperated with many car manufacturers is actually that it hopes to conduct some benign discussions on the future development direction of pure electric vehicles.

At first, this kind of discussion only existed inside Weilai, focusing on several managers from the State Grid and some Weilai suppliers.However, after more than a year’s efforts, the leaders of all enterprises in the power exchange alliance have reached a consensus and will seriously consider this issue.

Yang Chao believes that this is only the first step, but even so, it has great positive significance:Because through Weilai’s efforts, at least more car companies will realize that what kind of energy supplement scheme pure electric vehicles will adopt in the future requires not only serious thinking, but also pre-research in the next generation of vehicles, and more importantly, how to realize applications more quickly in the current scenario, which will have a chain effect on the whole industry.

However, in his mind, he still has his own ideas about the form of changing power stations in the future.

He told Leifeng. com(WeChat official account: Leifeng. com)"New Smart Drive", just like gas stations, has formed a complete power exchange network in the whole country, which can be operated by the state, enterprises or third parties. The battery also has a set of standard system, and there are several different types of batteries to choose from for different models or mileage requirements. Under such a system, car companies develop models without unnecessary consumption of batteries.

On the contrary, car companies can carry out in-depth exploration in the dimensions of safety, application service, reliability, vehicle intelligence and automatic driving, and hand over the matter of energy replenishment to social resources to solve. Only in the specific practice process, Wei Lai’s team found that the choice of social resources-overcharge scheme can not solve the problem of power grid, nor can it solve the problem of sustainable development, and Wei Lai believes that changing electricity will be the "ultimate scheme" for new energy.

Of course, behind this kind of industry recognition, in fact, different manufacturers compete for battery standards.

In the communication with many car companies, Yang Chao was asked countless times such as "Tesla and BYD have no power exchange business, why others’ sales are very good". For Weilai, even if you tell these friends that your sales are really driven by the power exchange business, it is easy to be questioned.

Therefore, on the one hand, Weilai suggested that these friends conduct user surveys to see how many consumers chose Weilai out of the ability to change electricity.

On the other hand, it launched a new brand-Ledao. Since its birth, Ledao has been highly anticipated, because its sales will influence the promotion of power exchange technology to a certain extent.

Launching vehicle models is an important strategic layout for Weilai to verify and promote its power exchange mode, while the previous experience of fast pile filling shows from another angle that in order to speed up the promotion of a new technology, the most important thing is to formulate industry standards.

According to Yang Chao, Weilai, as an organizational unit or an important participant in China, has participated in the formulation of more than 30 power exchange standards, including the formulation of key standards such as safety, system composition and terminology interpretation.

In addition, Wei Lai also presided over the formulation of some IEC (International Electrotechnical Commission) standards together with State Grid. In IEC, it is rare for Chinese to preside over the formulation of standards.

Yang Chao explained that power exchange technology is a brand-new technology in Europe, and there is no specific standard. In order to ensure that all services meet local standards and regulations, Weilai and relevant European institutions jointly formulated industry standards, which gradually evolved into IEC standards.

Yang Chao said that all standards were originally formulated for safety reasons. Although there is a certain foundation in Europe at present, it is necessary to further strengthen this sense of existence to attract more European enterprises to participate in this process and jointly promote the improvement of standards.

Next, Weilai will further optimize the design of standards, integrate more excellent standards from different enterprises or institutions (such as China Power Research Institute and China Automobile Research Institute) for the market to choose from, and at the same time open its own Konw how to promote the unification and improvement of relevant standards for power exchange technology.

Yang Chao said,The establishment of many standards takes quite a long period. For example, the nature, size, capacity, connector, battery management, adaptability of the three power systems, etc., all need to take time to demonstrate and analyze.Different manufacturers in the alliance have their own design specifications, and if they want to reach an agreement, they need technical compromises.

"This is like a unified charging port for mobile phones. How many years did it take?"

Yang Chao said that it is not that anyone with a loud voice or a strong ability can complete it dramatically in a short time, but what Wei Lai can do is to verify it realistically and coordinate within the alliance until someone is willing (compromise). Just lean together as much as possible. Wei Lai hopes to prove that he can do it first and then help more people.

As we all know, whether it is a charging pile or a power station, the cost is often high when car companies directly participate in the operation. It is easier to "get what you need" with the help of social resources. According to Yang Chao, Weilai has already reached a cooperation with Zhongan Energy in Anhui Province to promote the construction of 1,000 storage, charging and exchange stations based on Anhui and radiating the Yangtze River Delta and the whole country.

The first power exchange station jointly built by Weilai and Zhongan Energy was officially launched in Luoji Service Area of G40 Hushan Expressway in Lu ‘an City, Anhui Province on June 13th, which is also the first Weilai fourth generation power exchange station launched in Anhui Province.

Yang Chao said that Weilai has been exploring the possibility of cooperation with the government. On the one hand, the operation and maintenance cost of changing power stations is high. On the other hand, besides economic benefits, Weilai has wider cooperation space with the local government and can get more policy or other support. Next, it may reach similar cooperation with the Wuhan Municipal Government.

Overseas, the layout of Weilai is also very suitable for the actual situation of the country.

For example, in Denmark, where the power grid construction is not perfect, the power exchange station originally used to serve the automobile business has also played a role in alleviating the pressure on the local power grid. By charging during the wave valley period and discharging during the peak period, many power exchange stations even achieved a profit of more than 4,000 euros per day. To this end, Weilai also specially adjusted the construction strategy of power exchange stations in Denmark, and built more power exchange stations in places where electricity consumption fluctuated to adjust the local electricity consumption situation.

In Hungary, Weilai was originally affected by the epidemic and the transportation cost was high, so it opened a local factory, and then completed some assembly tests of vehicles in China, and left the rest of the work to the Hungarian factory, which greatly reduced the cost.

Hungary was originally short of natural resources, so the government is very interested in the energy storage project derived from Weilai Power Exchange Station, hoping to further cooperate with Weilai, and Weilai also intends to promote the power exchange station integrating electricity exchange and energy storage to the whole of Europe through the pilot project with Hungary.

According to Yang Chao, Weilai has projects in Denmark, the Netherlands and Hungary, and has also cooperated with some universities in Germany.

As the batteries of the first batch of electric vehicles gradually reach the limit of service life, how to recycle and reuse the batteries reasonably has become the focus of the industry.

As an advocate of power exchange technology, Weilai will also face this problem directly, and the power exchange station, as a natural "battery maintenance center", can play a positive role in prolonging the service life of batteries through more reasonable and optimized management of battery storage environment and charging power.

According to Yang Chao, Weilai is currently promoting the life-cycle management technology of batteries to extend the service life of batteries as much as possible, and at the same time, it has also invested in research and development of technologies related to automatic disassembly and refined recycling of batteries to maximize the value of batteries. With the opening of the power exchange network, there are many stories told by Wei Lai to exchange electricity.

The original article of Leifeng. com is prohibited from being reproduced without authorization. See the instructions for reprinting for details.

The latest news of H7N9 avian influenza: Another H7N9 patient died in Shanghai. The latest death toll in Shanghai is 16, and 33 people have been diagnosed with infection. According to the website of the State Health Planning Commission and media reports, as of June 27, 2013, 40 cases of H7N9 deaths were reported in mainland China. According to a study by the School of Medicine of the University of Hong Kong, the H7N9 epidemic has not passed, and it may reappear this fall.

According to the Shanghai Municipal Health and Family Planning Commission on the 26th, one case of human infection with H7N9 avian influenza died in Shanghai, and no new cases appeared. As of 16: 00 on the 26th, 33 cases of human infection with H7N9 avian influenza have been confirmed in Shanghai, of which 2 cases are under active treatment, 15 cases have recovered and discharged, and 16 cases have died after treatment.

Death patient Gu Mou, male, 56 years old, from Shanghai. On April 11, he was diagnosed as a confirmed case of human infection with H7N9 avian influenza. On April 19, he was transferred to the municipal public health clinical center for diagnosis and treatment. He died in the early morning of June 26 after active rescue.

In April this year, the first adult patient with H7N9 avian influenza in Shanghai was cured and discharged.

Has H7N9 passed? HKU School of Medicine says it will reappear this autumn.

According to the latest research released by Li Ka-shing Medical College of HKU on 24th, according to the seasonal epidemic trend of avian influenza A (H5N1), H7N9 may reappear this autumn. However, studies have also shown that the fatality rate of H7N9 infection in humans is slightly lower than that of H5N1.

At the same time, it was found that the incubation period of H7N9 was 3.1 days, which was shorter than 5 and 6 days in previous studies, and it was very close to the incubation period of H5N1 of 3.3 days. Liang Zhuowei, director of the Public Health Research Center of Li Ka-shing Medical College of the University of Hong Kong, pointed out that this achievement provided an important basis for clinical judgment and the length of the isolation period after the epidemic was discovered. It is understood that the isolation period is usually twice or two and a half times the incubation period, that is, 8 or 9 days of isolation is enough.

In addition, the study also provides evidence that H7N9 only has a low possibility of human transmission. After close follow-up of 2500 cases of contacts, only four potential secondary infections were found.

Liang Zhuowei said that the possibility of human-to-human transmission is not zero, but it is very close to zero. "That is, H7N9 has once again verified our previous suspicion that the risk of human-to-human transmission is quite low. That is, in most links, the infection comes from direct contact with birds. "

Based on the experience of H5N1 and seasonal epidemic trend, the research report thinks that H7N9 may reappear this autumn, which will be an opportunity to prepare for public health measures for disease prevention and control and strengthen the response ability to disease epidemic.

Observer Network synthesizes Xinhua News and Zhongxin News.

　　Ya ‘an, Sichuan News Network, January 24th (Reporter Liu Jiahong, Li Jingzhi) On January 24th, the reporter was informed that 13 baby pandas born in Ya ‘an, the "home of pandas" after the Wenchuan earthquake made a collective appearance to pay a New Year call to the people of the whole country.

Thirteen giant pandas pay New Year greetings to the people of the whole country.

　　The Wenchuan earthquake caused the transportation, water, electricity and communication of China Conservation Giant Panda Research Center in Wolong, Sichuan Province to be paralyzed, the enclosure was seriously damaged, and 63 giant pandas were trapped. On May 18th, 2008, giant pandas were safely transferred to Ya ‘an, Sichuan, where the world’s first giant panda was found. In order to ensure the normal life of the transferred giant panda, especially the pregnant giant panda, all the researchers of the China Research Center for the Protection of Giant Panda overcame difficulties, united as one, stuck to their posts, strengthened the management of the pregnant giant panda, carried out caring breeding and training, closely observed and monitored their behavior, and gradually eliminated the psychological impact of the giant panda after the earthquake.

　　On July 6th, 2008, the giant panda "Dong Dong" gave birth to the first pair of twin panda babies safely in Ya ‘an after the earthquake. Thirteen giant panda babies were born in Ya ‘an successively. On August 8th, 2008, the world’s only "Olympic" panda baby was born in Ya ‘an, creating a myth in the history of panda breeding. At present, 13 baby giant pandas are in good health and in good growth and development.

　　On the eve of the Spring Festival of the Year of the Ox, 13 baby giant pandas in Ya ‘an, Sichuan, paid a New Year greeting to all friends at home and abroad who care about giant pandas, wishing everyone a happy New Year and good luck in the Year of the Ox! I wish the great motherland prosperity, prosperity and national security!

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