Scientists develop new spacecraft outer protective materials

The academician team of Yu Shuhong, China University of Science and Technology, developed a new type of spacecraft outer protective material – polyimide-nano-macular composite film. This new material has been significantly improved due to its unique bionic design, and its mechanical properties and extreme environmental tolerance are significantly improved, which is expected to replace existing polyimide-based composite film materials. This results have been published in "Advanced Materials".

The polyimide film is a perfect material of the space detector "protective clothing" due to its excellent mechanical properties, excellent thermal stability and protruding chemical resistance. However, like other hydrocarbon polymers, the material is extremely susceptible to atomic oxygen attack in the space environment, causing its physical and mechanical properties to drop sharply, and there is currently no good solution. In addition, cosmic radiation and space debris impact also bring severe tests to their stability.

Yu Shuhong team is inspired by natural pearl mother’s "brick-mud" layered structure, using the pre-mechanical properties and ultraviolet mask function and can be prepared as a structural element, with polyimide precursor The polyimide-nanocomposite film is co-assembled, and the superior intrinsic characteristics of mica make up for the lack of polyimide. Different from the conventionally imitation pearl layer nanocomposite film, researchers have double-layer pearl layer structures by changing group distribution ratios, with a two-layer pearl layer structure, with a more dense nammother piece. This design strategy not only achieves effective improvement in material mechanical properties, but also facing atomic oxygen, ultraviolet radiation and spatial debris or the like.

Studies have shown that the tensile strength, Young’s modulus and surface hardness of this novel bionic composite film are 125 MPa, 2.2 Gpa and 0.37 GPpa, 45%, 100%, respectively, 100%, respectively, 100%, respectively, 100%, respectively, 100%, respectively, 100% And 68%, its performance is significantly better than the polyimide-mica composite film of the pure polyimide film, a single layer of pearl mother structure, and a polyimide-based composite containing conventional reports. In addition, its anti-ultraviolet aging and high temperature stability are also significantly improved.

The industry believes that this research proposed unique double imitation pearl mother structure design strategy, providing new ideas for designing other high-performance nanocomposites. (Guiyun An)

PIXEL 6 is safer than iPhone 12?

The latest report shows that Google Pixel 6 is safer than iPhone 12.

In September 2021, OMDIA researchers evaluated mobile equipment security, conducted investigations to 1520 smartphone users in 10 countries, including Apple, Google, Samsung and millet mobile phones. The results show that the Pixel 6 mobile phone running Android 12 is safer than the iPhone 12 running iOS 15.

? Identity protection

As the user’s most concerned security feature, Google Pixel 6 mobile phone has the highest score of identity protection because of the most identity options. Users can also choose one-time password, FIDO, push notification, etc., and Apple iPhone 12 is only dualistic certification. Apple iCloud is the largest of the industry is also the most successful double factor safety deployment example, Xiaomi and Samsung equipment also require users to register the corresponding account.

? Security update

Security updates are used to rate the time of security updates. Pixel 6 is also the highest, because Google mobile phone strictly provides five-year security update, although the iPhone does not give specific time, but general support time is 5 to 6 years. Samsung Galaxy S21 Ultra mobile phone provides a 4-year firmware update, Xiaomi provides two-year security update to all mobile phones, providing new devices for 4 years of security updates.

?cyber security

In the iPhone, both the web terminals and third-party applications may see the transmitted data during the data transfer process. However, from the Android 7 system, the third party APP on the Android device established a secure connection to the pre-installed certificate. Pixel is the only device that provides users with disabling 2G options because 2G security vulnerabilities are more than 3G, 4G, 5G.

Hardware security

These phones use different forms of hardware-based security. All mainstream Android devices use a trusted enforcement environment (TEE), which can be isolated from the operating system of the device to protect the sensitive data. Although there is no TEE in Apple devices, there are Secure Enclave Processors to protect and store sensitive information. The QUALCOMM SOC used by XIAOMI MI 11 5G has a security processing unit. Samsung S21 Ultra also has similar security processors and memory. The Tensor secure kernel of Pixel 6 fuses the new Titan M2 chip and trusted execution environment Tee.

? Anti-malware

Samsung, Google, Xiaomi equipment has built-in anti-malware solutions, which can protect and detect malware. Although Apple uses a shop, you can load an application outside the app store.

? Safety backup

The end-to-end encryption of the data that is backed up to the cloud can be implemented in the Pixel 6 phone. Data is encrypted during storage and transmission, even if Google does not access and decode. Millet and Apple devices have different levels of encryption, but it is impossible to ensure that the cloud service provider cannot access backup data. End-to-end encryption of Apple-sensitive information is only available for dualistic authentication.

? Lost equipment

Each vendor provides information based on web-based tools to locate, trigger, locked, and clears information about theft device. But only Google and Apple have developed a corresponding mobile app. Xiaomi also provides an optional feature that is positioned by mobile phones, but only Google’s Find My Device App is downloaded separately.

Physical access control

All participating equipment provides different types of biological access control, including facial recognition, fingerprint recognition, and the like. Most equipment vendors provide temporary ban biometric options, but Xiaomi MIUI 12 system no longer provides this option.

? Anti-fishing protection

The anti-fishing protection function is seen by consumers as a very important mobile phone security feature. Google’s Messaging App requires users to apply spam protection features, which is closed by default. If this feature is not turned on, SMS fishing attempts will not be marked. Similarly, in the millet MI browser, there is no warning after the fishing link is clicked. The enhanced anti-fishing protection function of the Chrome browser is not open by default, and users can enhance security protection by using Google App. Apple iPhone 12 can detect phishing attacks in the Safari browser, and the device has a function of intercepting harassment phones. Use Google Safety Browse (Safe Browsing) can detect fishing and malware URLs. In the Pixel device running Android 12, there is an additional anti-fishing detection, and suspicious news in the third-party message app, the user will receive a warning message.

Reference and Source: https: //

Not a ancestral treasure knife design: Samsung S22 accessories exposure

The current image flagship camera is getting more and more shocked. How to do it is really difficult, Samsung next-generation flagship S22 is not exposed soon, using "treasure knife" camera design, netizens straightTall tall.

Later, S22 Ultra’s real machine map was also exposed, and the camera did not use this integrated treasure knife design, but each lens, the flash is independently designed.

Recently, some of the Samsung S22’s partial accessories are exposed, such as mobile shells, tempered films, however, some mobile phone shells camera portions use this kind of treasure knife design, some people may have not seen the tri-machine, and received misleading of mobile phone shell design, think reallyThe machine camera is also like this.

If this is the case, the small partner who doesn’t like the treasure knife camera can be honest. [Dog Head] …

Simple understanding of laser principle, learn a knowledge point daily

Laser, it should be said to be a household name, but if you really ask what is laser, I am afraid there will not be too many people to say it accurately. Laser, English is Laser, this Chinese name is very controversial, "Lease", "Thunder", "Light Edge", "Light Surplus Amplifier", how to call it, It seems that there is nothing to hear the word laser, I think that there is a relationship with the radium of the lady. Now I think is that it is one of the translations of Laser. Fortunately, there is the finals of Qian Xue Sen, this thing is also an official Chinese name. . The word Laser comes from the English first letters of five vocabulary.Light Amplification by Stimulated Emission of RadiationDirect translation is called the exciter radiation amplifier, although it is not like the cooling of the laser, but for the scientific research dogs of our related majors, this full name is very refined, the principle of laser production.

If you want to mention the principle of laser, you can’t really be anxious. You have to go around a big bend. If you come over, you will have a little stimulus for students who don’t know this.

The principle of laser must be said from the particle energy in the substance, and must be a specific particles in some particular substances, there are two or more energy states, sometimes in high energy, exciting, sometimes Low energy, like two or three o’clock in the morning.

When the particles are relaxed from high energy into low energy, the loss of loss is radiated in the form of photons.

The light source such as an incandescent lamp is emitted by spontaneous radiation. The number of high energy particles after power is increased, and spontaneous radiation occurs very frequently.

This process is calledSpontaneous radiationIt should be easy to see here, which is not a laser, although it is also light, it is not a laser, anyway is not a laser.

Spontaneous radiation is very tone, if the laser photon is like the military parade in Tiananmen Square, the spontaneous radiation photon is like a group of dissembled wild dogs, there is no organization of discipline, and its occurs, sometimes Come, sometimes chaos.

Since the excitement particles will lose energy to be slight, then, will it be exciting to get energy through some approach? The answer is affirmative, similar to the radiation process, the low energy particles will keep the passenger passing the photons, seeing the right will "hijack", sweep the energy of the photons, used to rise to high energy This process is calledAttractive absorption.

In 1917, Einstein proposed an idea, high-energy particles, may also like to stare at the photons passing by, when there is a favorite photon road, high-energy particles will not keep them, but to release energy with it. Walk, like love. The original particles lose energy, from high energy changes to low energy, and the variation of energy will generate a superior photon with the passing photons, this process is calledExcited radiation.

Radiation is the core portion of the laser, which can be seen as light before and after the radiation is amplified, and the resulting photon is consistent with the frequency of the original photon, which is the so-called coherence.

The passed photons are two changes from one change, that is, light is enlarged. At this time, the primary school language foundation is keenly discovered that the radiation radiation is amplified. The keywords of this name have all appeared, but it is still calm. At this time, the light still cannot be called laser, and there are two important issues need Solved, it is spontaneously radiation and attachment absorption introduced by the front pad.

The first thing to overcome is attractive. If the particles of the high and low level are staring at the photons passing, it is difficult to ensure that the last thing is more hijacked or the photons that are released. And in fact, the low-level particles under natural conditions are more than high-level particles. Here, you need to join the first person-oriented intervention, that is, in a way, let the low-level particles run to the high energy level, let everyone Are exciting. At this time, there is a very Cooool name, calledParticle number inversionOrExcited state. The method of producing particle number inversion varies depending on the substance used for radiation to generate laser light, which may be energized, or light, in summary is a means of input energy.

When the excited radiation is much greater than the charge absorption, it can begin to face another mountain, spontaneous radiation. Spontaneous radiation is naturally occurring in high energy particles. In other words, there is a high energy particle, it may happen, let alone, it has raised the low energy particles to high energy, and the spontaneous radiation process is naturally stopped. So the idea of ??solving the problem is that if you want to make the radiation much greater than spontaneous radiation.

The method is to add two mirrors on both ends of the working substance of the particle number inversion state, one end is a full mirror, and the other end is a portion of the mirror, which is referred to as a resonant cavity. When the exciusal radiation occurs, the appropriate photons are repeatedly jumped between the two mirrors, multiple times, repeatedly generates electrical radiation, and continuously enhances the beam.

A portion of the mirror can be transmitted at any time, and as the radiation is contrast, the transmitted beam is constantly enhanced. Since the two-sided mirrors are located in a particular direction, there is no stable oscillating for the direction in which the direction is not suitable, so that we can see that the laser has a clear direction, which is also the result of the resonant cavity screening.

It can be seen that as long as the light in line with the requirements can form a stable shock in the cavity, it is constantly being large, which is why the laser has a clear direction, as the propagation direction does not meet the requirements of the required light is screened.

This is also the basic principle of laser, and we will be asked to remember the three major elements of laser when learning laser principles.Working substance (gain medium),Pump source (energy input),Cavity, Understand and understand this, it is also possible to understand how the laser is generated, and under this condition, it is possible to determine that many lights seen in life are not laser.

For example, when the sun is laser? This is definitely not, according to the above, the laser is not natural, the sun is emitted by nuclear gatherings, and it is not the result of the radiation radiation. This should be everyone’s consensus, there is nothing to say . Is this laser pen playing in a child? Is this a laser? This is also likely to be laser, exclude individuals to take ordinary light-emitting diode confused, many laser pens use things such as laser diodes, of course, cost is also very low, as laser, intensity, coherence, etc. It is also quoruting, after all, the use is different. Is the laser sword inside the Science Fiction Movie Star War? Although the laser cutting is now doing, let the laser only spread a certain distance, do not spread this, it can’t be done, the things in the movie can be called the telescopic diode, and it will be a light without this idea. The sword came out, the cost is not high.

I didn’t just say a bunch, this is the first time I know about it, this year’s international light days, because of the organizers of the event, I was asked to write an article about science laser. I want to revise the article, I want to revise it. I would like to revise it. Although I am related to major, it is not studying the laser, the understanding is limited. In the future, there will be some other interesting optical knowledge. Of course, it is mainly to science. Try to avoid too deep.

I hope that the people in this article are mainly some non-professional people, or undergraduates must learn laser principles, or they have not learned, and even have just read research, but even have no entry levels of laser principles. People, can qualify first, what is the principle of the laser, and then fill the flesh and blood to understand the laser or enter the research work, of course, the professionalism is also welcome to criticize. If the response or if there is any reaction, I will write some articles about fiber communication, Fourier optical, nonlinear optical, and so on.

Author: Fu Ye Lei Lei know