This year, the level of science has been constantly refreshed
●The recognition accuracy rate of the storage and calculation integrated architecture on the handwritten digit set reaches 96.19%
●As of 21.00 on December 14, the "Tianwen-1" probe has been in orbit for 144 days, with a flight mileage of approximately 360 million kilometers and a distance of more than 100 million kilometers from the earth
●Chang'e-5 has gone through 11 phases and 23 days of on-orbit work, collecting about 1731 grams of lunar samples and returning to Earth
● "Struggle" has created a new record of 10,909 meters for manned deep diving in China
●Calculating the "Gaussian Bose sampling" problem, processing 10 billion samples, "Nine Chapters" only takes 10 hours, and supercomputers require 120 billion years
●China and Nepal jointly announced the "new height" of Mount Everest-88.886 meters
The year 2020 will be an extraordinary year. In this year, the sudden new crown pneumonia epidemic disrupted the rhythm of people's lives and work, but the struggling pace of the scientific community has never stopped, and in the process of fighting hard, it has become more and more courageous.
"Tianwen 1" started a new journey for mankind to explore Mars, Chang'e 5 brought back gifts from the moon, and "Struggle" created a new record for China's manned deep diving... This year, scientists are searching up and down. Light up the wider world and open up a brand new world on the road of chasing truth. The sea is the mainstay, and as science continues to be refreshed, a more exciting future is unfolding before our eyes.
Our reporter Fu Lili
"Tianqin No. 1" passed technical on-orbit verification
Every technical index is better than the mission target
The "Tianqin-1" satellite is the first technical verification satellite of my country's "Tianqin" gravitational wave detection program. Its core task is to verify space inertial reference technology, which is one of the core technologies in the space gravitational wave detection technology system, including The three key technologies of high-precision inertial sensing, micron-level continuous adjustable micro-propulsion and drag-free control, as well as high-precision laser interferometry technology, high-stability temperature control technology and high-precision center of mass control technology.
On January 18, good news came from Institute 502 of the Fifth Academy of China Aerospace Science and Technology Corporation. According to the analysis of the latest test results, the "Tianqin-1" satellite has successfully completed the flight verification without towing control.
According to reports, tow-free control refers to the force that eliminates all interference with the satellite except gravity, including sunlight pressure, atmospheric resistance, etc., to ensure that the satellite is in a "super quiet and super stable" state.
Drag-free control is divided into acceleration mode and relative displacement mode.
Since it is necessary to always ensure that the satellite is not interfered by forces other than gravity, drag-free control faces greater challenges from model establishment, algorithm design to satellite platform control.
From the flight data, in the acceleration mode, after the implementation of the drag-free control, the influence of the external interference force of the "Tianqin-1" satellite on the acceleration is reduced to less than one 400 millionth of the gravitational acceleration, which is better than the ESA "GOCE" (Detection of Gravity Field and Steady Ocean Circulation) One-300 millionth of satellite is much smaller than the acceleration caused by yawning.
The successful verification of the towing-free control technology of the "Tianqin-1" satellite in orbit shows that my country has taken a solid step towards space gravitational wave detection, but there is still a certain distance from the real gravitational wave detection application.
On May 21st, Luo Jun, the chief scientist of my country’s space gravitational wave detection "Tianqin Project", said that after multiple evaluations, all the six major technologies of the "Tianqin-1" satellite passed the on-orbit verification, and each technical index was better than the mission target .
Multi-array memristor storage-calculation integrated system comes out
Break the computing power bottleneck and meet the high demand of complex tasks
In February, the team of Professor Qian He and Wu Huaqiang from the Institute of Microelectronics of Tsinghua University and Beijing Future Chip Technology Innovation Center and their collaborators announced that they had successfully developed the world’s first multi-array memristor storage-calculation integrated system. The energy efficiency of the product neural network is two orders of magnitude higher than that of the graphics processor chip, which breaks through the limitations of the traditional computing framework to a certain extent, greatly increases the computing power of computing equipment, and reduces the power consumption of traditional chips by 100 times.
Related results were published in the journal Nature.
How to use the integration of computing and storage to break through the AI computing power bottleneck is a hot spot in domestic and foreign scientific research in recent years.
Finding the right hardware is one of the foundations for increasing computing power.
The team successfully fabricated high-performance memristor arrays by optimizing materials and device structures.
In order to solve the problem of the decrease in system recognition accuracy caused by the non-ideal characteristics of the device, they proposed a new hybrid training algorithm, which only needs to train the neural network with fewer image samples and fine-tune the partial weights of the last layer of the network. Make the recognition accuracy rate of the storage and calculation integrated architecture on the handwritten digit set reach 96.19%.
At the same time, the team also proposed a spatial parallel mechanism to program the same convolution kernel into multiple groups of memristor arrays. Each group of memristor arrays can process different convolution input blocks in parallel, increasing the degree of parallelism to accelerate convolution calculations.
On this basis, the team built a complete storage-calculation system composed of all hardware, integrated multiple memristor arrays in the system, and efficiently ran the convolutional neural network algorithm on the system, successfully verifying image recognition The function proves the feasibility of full hardware implementation of the storage-computing integrated architecture.
"The new storage-computing integrated architecture based on memristors can break the computing power bottleneck and meet the high demand for computing hardware for complex tasks such as artificial intelligence." said team member and professor of Tsinghua University's Advanced Chip Technology Innovation Center Wu Huaqiang.
The world's first human cell map was successfully drawn
Realize the digitization of human cells
The team of Professor Guo Guoji of Zhejiang University School of Medicine used the analysis platform independently developed to draw the first human cell map.
On March 26, the top international journal Nature published the results of this research online.
Cells are the basic unit of life.
In the past, scientists mainly used techniques such as microscopy and flow analysis to classify and identify cells of different species in nature based on several phenotypic characteristics.
The emergence of single-cell sequencing technology has brought revolutionary changes to this traditional cell cognition system.
The research team performed high-throughput single-cell sequencing analysis on 60 human tissue samples and 7 cell culture samples, and systematically mapped human cell maps spanning the embryonic and adult stages, covering eight systems, and established more than 700,000 human cells. A single-cell transcriptome database has identified more than 100 cell types and more than 800 cell subtypes of the human body, developed a single-cell comparison system, and built a human cell blueprint website.
Guo Guoji introduced that this work is, in a nutshell, the digitization of human cells.
Use a digital matrix to describe the characteristics of each cell and classify them systematically.
In addition, many previously unknown cell types were defined and some special expression patterns were discovered.
Through the human cell atlas, the team found that a variety of adult epithelial, endothelial and stromal cells also play the role of immune cells in tissues.
In addition, through cross-period and cross-tissue cell atlas analysis, the team revealed a universal mammalian cell fate determination mechanism: the transcriptional status of stem cells and progenitor cells is mixed and random, while the transcriptional status of differentiated and mature cells becomes different. Clear and stable, that is to say, cell differentiation has undergone a development process from chaos to order.
This research is the first to comprehensively analyze the types of human cells in embryos and adulthood at the single-cell level. The research data will become a treasure house of resources for exploring the mechanism of cell fate determination, and will also have a profound impact on the identification of normal and diseased cell states of the human body.
In the future, clinicians are expected to identify abnormal cell states and origins by referring to normal cells.
"Tianwen-1" starts a new journey of Mars exploration
Complete the three goals of "surround, land, and patrol detection" at one time
On July 23, my country successfully launched the first Mars exploration mission "Tianwen No. 1" probe with the Long March 5 Yaosi carrier rocket at the China Wenchang Space Launch Site on the northeast coast of Hainan Island. The rocket successfully sent the probe into a predetermined orbit. Starting the journey of exploring Mars is the first step in my country's autonomous planetary exploration.
The international exploration of Mars started in the 1960s.
As of the end of June 2020, humans have carried out more than 40 missions to Mars, of which 24 were successful.
Although my country’s first Mars exploration mission started late, it has a high starting point and a large span. From the beginning of the project, it aimed at the current world advanced level to determine the mission goal. It clearly proposed that it will complete the three major "surround, landing, and patrol exploration" through one launch for the first time in the world. aims.
If this goal can be successfully achieved, my country will become the second country in the world to independently master Mars landing patrol detection technology.
According to reports, a successful launch is only the first step of the mission. The mission's flight process includes six stages: launch, ground fire transfer, Mars capture, Mars mooring, off-orbit landing, and scientific exploration.
Compared with lunar exploration, Mars exploration missions are more difficult.
Because Mars is relatively far away from the Earth, it has high requirements for launching, orbiting, control, communication, and power technologies.
As of 21:00 on December 14, the "Tianwen-1" probe has been in orbit for 144 days, with a flight mileage of about 360 million kilometers, a distance of more than 100 million kilometers from the earth, and a distance of about 12 million kilometers from Mars. The flight is in good condition.
Chang'e 5 went to the moon to "dig earth"
Writing a new chapter in human lunar exploration
On November 24, China's lunar exploration project Chang'e-5 probe successfully lifted into space at the Wenchang Space Launch Site, starting China's first return trip to sample extraterrestrial objects.
This is the sixth mission of the lunar exploration project, and it is also one of the most complex and difficult missions in my country's aerospace industry so far.
On December 17, with the complete success of the Chang'e-5 mission, mankind once again obtained lunar samples in 44 years.
This mission opened a new chapter in the automatic sampling of the moon and bringing the samples back to the earth. It is of "revolutionary" significance for increasing humanity's understanding of the history of the moon.
"Digging" to the moon is a popular interpretation of the Chang'e-5 mission.
In fact, the Chang'e-5 mission will focus on achieving three major engineering goals. One is to break through a series of key technologies to improve my country's aerospace technology level; the other is to achieve the first automatic sampling and return of extraterrestrial celestial bodies and promote a major scientific and technological leap in my country; It is to improve the lunar exploration engineering system and lay a certain talent, technology and material foundation for manned moon landing and deep space exploration.
In addition, a series of scientific explorations will be carried out, such as on-site investigation and analysis of the landing zone, and analysis and research of lunar samples.
The entire mission, Chang'e-5, went through 11 phases and 23 days of on-orbit work, collecting about 1,731 grams of lunar samples and returning to Earth.
Experts said that the successful completion of the Chang'e-5 mission has achieved 5 "firsts" in the history of China's spaceflight: one is the sampling and packaging of extraterrestrial objects, the second is the takeoff of extraterrestrial objects, the third is the lunar orbital rendezvous and the fourth is carrying. The high-speed earth re-entry of samples, the fifth is the storage, analysis and research of samples.
This is a major leap in my country's space technology and provides important support for us to further understand the moon.
"Struggle" returned to sail smoothly
Set a new record for China's manned deep diving
On November 10, the Struggle set a new record of 10,909 meters for manned deep diving in China, and returned smoothly on November 28.
This indicates that my country has the ability to enter the deepest part of the world's oceans to carry out scientific exploration and research, and reflects my country's comprehensive strength in the field of marine high-tech.
The deepest known ocean, the Mariana Trench in the Western Pacific, is a plate subduction zone with active geological movement, high water pressure, low temperature, and complete darkness. It is called the "fourth pole of the earth."
Scientific research on the abyss, including the detection of the Mariana Trench, helps scientists understand the material composition and genesis of seabed organisms, mineral deposits, seamounts and volcanic rocks, and the role of deep-sea trenches in regulating climate.
The Struggle is a 10,000-meter manned submersible independently designed and integrated by my country.
Its successful development has significantly improved my country's manned deep-sea technology and equipment capabilities and independent innovation level, and provided another weapon for my country to explore the mysteries of deep-sea science, protect and rationally use marine resources.
In the second phase of the 10,000-meter sea trial mission, the sea trial team overcame difficulties such as typhoon, rain, high temperature, and high sea conditions, and conducted a number of acceptance tests. They also carried out the deep-sea video lander "Canghai" and "Struggle". Joint operations.
During the sea trial, a batch of sediment, rock and seabed biological samples were obtained.
The successful sea trial of the Struggle fully verified the various functions and performances of the submersible as well as my country’s breakthroughs in deep-sea equipment and deep-sea technology, marking my country’s entry into the first echelon of deep-sea scientific expeditions, and will be the follow-up of my country’s deep-sea sciences Research provides strong technical support.
The artificial sun begins to discharge
Speed up the pace of human exploration of future energy
On December 4th, my country’s new generation of controllable nuclear fusion research equipment "China Circulator No. 2 M" (HL-2M) was formally completed in Chengdu to discharge the magnetic phenomenon, fluid instability, and confined turbulence of ultra-high temperature plasma. Frontier research is of great significance, marking that my country has officially entered the forefront of global controllable nuclear fusion research.
It is also an important support for the International Thermonuclear Experimental Reactor Project (ITER) and will further accelerate the pace of human exploration of future energy.
Nuclear fusion polymerizes deuterium and tritium ions into helium, and the mass lost during the polymerization is converted into super energy. This is the same as the principle of solar luminescence heating, so the controllable nuclear fusion research device is also called "artificial sun".
Controllable nuclear fusion requires ultra-high temperature, ultra-high density and other conditions. Most advanced tokamak devices are used to confine plasma at 100 million degrees Celsius in a vacuum chamber through an ultra-strong magnetic field to reach the reaction conditions.
At present, the world is jointly exploring its implementation methods and building a simulation experiment platform.
HL-2M is the "artificial sun" with independent intellectual property rights, the largest scale and the highest parameters in my country.
"The discharge is to make the gas in the HL-2M vacuum chamber into a plasma state. Our researchers will perform different types of discharges on this device. The ultimate goal is to heat enough plasma to over 100 million degrees Celsius. Our Sun The core temperature is 15 to 20 million degrees Celsius, which is equivalent to nearly 10 times the temperature of the solar core. Only when the plasma is heated to more than 100 million degrees Celsius can controllable nuclear fusion be possible." Relevant researchers said.
The International Thermonuclear Fusion Experimental Reactor Project is the world’s largest and most influential international science project. my country formally signed a contract to join the project in 2006.
Scientists from France, Japan, the United States, and the United Kingdom have been conducting joint research in Chengdu for many years, and the establishment of the "Sino-French Joint Experimental Week" has promoted the progress of related scientific research around the world.
Quantum computing prototype "Nine Chapters" made a major breakthrough
Complete 100 million annual tasks of classic supercomputers in one minute
On December 4, the University of Science and Technology of China announced that the 76-photon quantum computing prototype "Nine Chapters" developed by the school's Pan Jianwei, Lu Chaoyang and other scholars will solve the mathematical algorithm "Gaussian Bose sampling" and process 50 million samples. It takes 200 seconds, and the fastest supercomputer in the world currently takes 600 million years to perform the same operation.
Related papers were published online in the international academic journal "Science".
The reviewers of "Science" magazine commented that this is "a most advanced experiment" and "a major achievement."
According to Pan Jianwei's team, the reason why this quantum computer was named "Nine Chapters" is to commemorate the ancient Chinese mathematics monograph "Nine Chapters of Arithmetic".
Quantum computers have ultra-fast parallel computing capabilities, which achieve exponential acceleration in some major problems through specific algorithms.
The "Gaussian Bose sampling" problem solved by "Nine Chapters" is one of them.
"Gaussian Bose Sampling" is an algorithm for calculating probability distribution, which can be used to encode and solve a variety of problems.
The difficulty of calculation is increasing exponentially, and it is easy to exceed the calculation capacity of current supercomputers, and it is suitable for quantum computers to explore and solve.
How powerful is the computing power of "Nine Chapters"?
Operate at room temperature (except for the photon detection part, which requires 4K low temperature), calculate the "Gaussian Bose sampling" problem, process 10 billion samples, "Nine Chapters" only need 10 hours, and supercomputers need 120 billion years-and the universe It is only about 13.7 billion years since its birth.
"The'Nine Chapters' completed the task that the classic supercomputer could only complete in 100 million years in one minute." The researchers introduced.
It has to be said that it has promoted the frontier research of global quantum computing to a new height.
Although there is still a long way to go before practical applications, it has successfully achieved a milestone breakthrough in the "superiority of quantum computing".
Mount Everest has a "new height"
Adopt "air-space-ground integration" full coverage measurement
On December 8, China and Nepal jointly announced the "new height" of Mount Everest-88.886 meters.
Prior to this, on May 27th, eight top team members of the Mount Everest elevation measurement team climbed from the north slope to the summit and completed the task of measuring the summit. The 2020 Mount Everest "height measurement" field operation successfully concluded.
It is understood that this time Mount Everest has set a number of firsts in its "height measurement".
The summit Global Navigation Satellite System (GNSS) survey relies on the Beidou satellite navigation system independently developed by China for the first time; humans carried out gravity measurement on the summit of Mount Everest for the first time to improve the height accuracy of Mount Everest; the team members stayed on the summit for 150 minutes, during which they were also carried out Measurements such as snow depth and meteorology on the summit created a new record for the length of time the Chinese stayed on the summit of Mount Everest.
According to experts, the so-called elevation refers to the distance from a point along the vertical line to the absolute base surface.
To measure elevation, first determine an "origin".
The legal starting surface for elevation in my country is the mean sea level of the Yellow Sea, and the elevation of Mount Everest is the height difference between the top rock surface and the mean sea level of the Yellow Sea.
According to reports, the height measurement of Mount Everest was carried out in sections. The leveling method was adopted from the reference point in Lhaze, Tibet to the first half of the foot of Mount Everest. A benchmark was erected every tens of meters and measured by a level. Height difference, one by one, the height difference is added up.
When the precise elevation is transferred to the intersection of the six peaks, the measurement target erected on the top of Mount Everest is used to measure the elevation difference of the peak relative to these points using the triangular elevation intersection measurement method.
Finally, the elevation of Mount Everest is determined by correcting calculations in various aspects such as gravity and atmosphere.
In addition to the basic methods of leveling and triangular elevation intersection measurement, the "height measurement" of Mount Everest can be said to be an "air-space-ground integration" full-coverage measurement, comprehensively using GNSS measurement, snow depth radar measurement, gravity measurement, satellite Various traditional and modern measurement techniques such as remote sensing and geoid refinement have made the "height" of Mount Everest more accurate.