Beijing, China

Beijing Institute of Technology , is a co-educational public university, located in Beijing, China. Established in 1940 in Yan'an, the university is now under the direct administration of the Ministry of Industry and Information Technology.As a member university of National Key Universities, “Project 211” and “Project 985”, it has been given priority for development from the Chinese government, the Commission of Science, Technology and Industry for National Defense, the Ministry of Education and the Beijing Government. Wikipedia.


Time filter

Source Type

The present disclosure is to provide a divided-aperture laser differential confocal Brillouin-Raman spectrum measuring method and the device thereof, which belongs to microscopic spectrum imaging field. By using the abandoned Rayleigh scattering light in the traditional confocal Raman spectrum detection, a divided-aperture laser differential confocal microscopy is constructed to realize high resolution imaging of three-dimensional geometrical structure of the measured sample. In addition, the characteristic that the zero-crossing point of the divided-aperture laser differential confocal imaging device accurately corresponds to the focus of objective is used to control the spectrum detector to accurately capture the excited Raman spectrum information excited at the focus of the objective, thereby achieving the detection of micro-area geometrical structure and spectrum information of the measured sample with high-spatial resolution, that is achieving mapping-spectrum with high-spatial resolution, and balancing resolution and measuring range. By complementing the advantages of confocal Raman spectrum detecting technology and confocal Brillouin spectrum detecting technology, the confocal spectrum detecting solution which detects the Raman spectrum and Brillouin spectrum at the same time is designed, the multi-property parameters of materials are measured and decoupled in composite.


A method for simulating a posture of a flexible cable based on a spring-mass model combining bending and torsion includes: establishing a physical property model of the cable, wherein a torsion property is represented by a torsion spring attached at each 55 cable segment; obtaining an initial position of each discrete mass point based on a total length of the cable and the number of the cable segments; identifying discrete mass points at both ends as fixed points, and obtaining their position information; calculating stress information of other discrete mass points whose position information is not determined based on the physical property model; sequentially calculating 10 10 equilibrium positions of the other discrete mass points by using the stress information and the initial positions to obtain their the position information; and simulating a stable posture of the cable based on the position information of the fixed points and the other discrete mass points.


Patent
Beijing Institute of Technology | Date: 2017-01-09

The invention relates to a method for reducing the PAPR in FRFT-OFDM systems, which belongs to the field of broadband wireless digital communications technology. The method is based on fractional random phase sequence and fractional circular convolution theorem, which can effectively reduce the PAPR of the system. The method of the invention has the advantages of simple system implementation and low computational complexity. In this method, the PAPR of the system can be effectively reduced while maintaining the reliability of the system. When the number of candidate signals is the same, the PAPR performance of the present method was found to be almost the same as that of SLM and better than that of PTS. More importantly, the present method has lower computational complexity than that of SLM and PTS methods.


Patent
Beijing Institute of Technology | Date: 2016-10-14

The present invention provides a system and a method for reducing the space charge effect in a linear ion trap. The system includes a linear ion trap, a first AC power supply, a second AC power supply, and a RF power supply. The linear ion trap includes four identical electrode rods, where two poles of the first AC power supply are respectively connected to two of the electrode rods, and two poles of the second AC power supply are respectively connected to the other two electrode rods. Two poles of the RF power supply are respectively connected to the first AC power supply and the second AC power supply. The first AC power supply and the second AC power supply provide sinusoidal AC signals. The present invention reduces the resolution decrease caused by the space charge effect, thereby improving analytical performance in mass spectroscopy.


News Article | May 19, 2017
Site: www.techradar.com

Every Star Wars fan understands the importance of a hologram – those messages could mean life or death in a galaxy far, far away. For years, optical engineers have been trying to create freestanding holograms – three-dimensional images created with lasers – and have achieved some success, like the virtual image of Tupac Shakur at Coachella 2012 or, more recently, the hologram of French presidential candidate Jean-Luc Melenchon. But these aren’t true holograms, they’re near approximations. To create perfect holograms, a medium of certain thickness needs to be modified in such a way that different sections reflect light in different phases. That thickness has usually been around a few millimeters at the minimum. A team of Australian and Chinese scientists, however, have created the ‘world’s thinnest hologram’ on a medium that’s 1,000 times thinner than a human hair. Led by RMIT University's Distinguished Professor Min Gu, the team used a 25-nanometer-thick material called a topological thin film insulator and carefully controlled lasers to encode a holographic image that can be viewed without the aid of 3D goggles. The technology is apparently simple and, thanks to its nano-scale size, could well be integrated into consumer electronics like smartphones, tablets and television sets, ushering in a new age of three-dimensional entertainment and communication. "Conventional computer-generated holograms are too big for electronic devices but our ultrathin hologram overcomes those size barriers," Professor Gu explained. "Our nano-hologram is also fabricated using a simple and fast direct laser writing system, which makes our design suitable for large-scale uses and mass manufacture." It’s needs to be noted that the prototype created by the team doesn't produce freestanding holograms. Instead, the technology manipulates light like any standard flat hologram, but produces phase shift at much higher resolutions for more detailed images that appear to pop off the surface. Citing examples for uses for this technology, Professor Gu added, "Integrating holography into everyday electronics would make screen size irrelevant – a pop-up 3D hologram can display a wealth of data that doesn't neatly fit on a phone or watch. From medical diagnostics to education, data storage, defence and cyber security, 3D holography has the potential to transform a range of industries and this research brings that revolution one critical step closer." "The next stage for this research will be developing a rigid thin film that could be laid onto an LCD screen to enable 3D holographic display,” added Dr Zengyi Yue from Beijing Institute of Technology (BIT), who is part of the Chinese team working with RMIT. “This involves shrinking our nano-hologram's pixel size, making it at least 10 times smaller.” So, how long before our smartphones get 3D display capabilities? Gu says that would depend on money matters. “If there’s a proper partner, in five years’ time we could see some real products.”


News Article | May 18, 2017
Site: www.sciencedaily.com

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday electronics like smart phones, computers and TVs. Interactive 3D holograms are a staple of science fiction -- from Star Wars to Avatar -- but the challenge for scientists trying to turn them into reality is developing holograms that are thin enough to work with modern electronics. Now a pioneering team led by RMIT University's Distinguished Professor Min Gu has designed a nano-hologram that is simple to make, can be seen without 3D goggles and is 1000 times thinner than a human hair. "Conventional computer-generated holograms are too big for electronic devices but our ultrathin hologram overcomes those size barriers," Gu said. "Our nano-hologram is also fabricated using a simple and fast direct laser writing system, which makes our design suitable for large-scale uses and mass manufacture. "Integrating holography into everyday electronics would make screen size irrelevant -- a pop-up 3D hologram can display a wealth of data that doesn't neatly fit on a phone or watch. "From medical diagnostics to education, data storage, defence and cyber security, 3D holography has the potential to transform a range of industries and this research brings that revolution one critical step closer." Conventional holograms modulate the phase of light to give the illusion of three-dimensional depth. But to generate enough phase shifts, those holograms need to be at the thickness of optical wavelengths. The RMIT research team, working with the Beijing Institute of Technology (BIT), has broken this thickness limit with a 25 nanometre hologram based on a topological insulator material -- a novel quantum material that holds the low refractive index in the surface layer but the ultrahigh refractive index in the bulk. The topological insulator thin film acts as an intrinsic optical resonant cavity, which can enhance the phase shifts for holographic imaging. Dr Zengyi Yue, who co-authored the paper with BIT's Gaolei Xue, said: "The next stage for this research will be developing a rigid thin film that could be laid onto an LCD screen to enable 3D holographic display. "This involves shrinking our nano-hologram's pixel size, making it at least 10 times smaller. "But beyond that, we are looking to create flexible and elastic thin films that could be used on a whole range of surfaces, opening up the horizons of holographic applications."


News Article | May 18, 2017
Site: www.eurekalert.org

Nano-hologram paves way for integration of 3-D holography into everyday electronics An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday electronics like smart phones, computers and TVs. Interactive 3D holograms are a staple of science fiction - from Star Wars to Avatar - but the challenge for scientists trying to turn them into reality is developing holograms that are thin enough to work with modern electronics. Now a pioneering team led by RMIT University's Distinguished Professor Min Gu has designed a nano-hologram that is simple to make, can be seen without 3D goggles and is 1000 times thinner than a human hair. "Conventional computer-generated holograms are too big for electronic devices but our ultrathin hologram overcomes those size barriers," Gu said. "Our nano-hologram is also fabricated using a simple and fast direct laser writing system, which makes our design suitable for large-scale uses and mass manufacture. "Integrating holography into everyday electronics would make screen size irrelevant - a pop-up 3D hologram can display a wealth of data that doesn't neatly fit on a phone or watch. "From medical diagnostics to education, data storage, defence and cyber security, 3D holography has the potential to transform a range of industries and this research brings that revolution one critical step closer." Conventional holograms modulate the phase of light to give the illusion of three-dimensional depth. But to generate enough phase shifts, those holograms need to be at the thickness of optical wavelengths. The RMIT research team, working with the Beijing Institute of Technology (BIT), has broken this thickness limit with a 25 nanometre hologram based on a topological insulator material - a novel quantum material that holds the low refractive index in the surface layer but the ultrahigh refractive index in the bulk. The topological insulator thin film acts as an intrinsic optical resonant cavity, which can enhance the phase shifts for holographic imaging. Dr Zengyi Yue, who co-authored the paper with BIT's Gaolei Xue, said: "The next stage for this research will be developing a rigid thin film that could be laid onto an LCD screen to enable 3D holographic display. "This involves shrinking our nano-hologram's pixel size, making it at least 10 times smaller. "But beyond that, we are looking to create flexible and elastic thin films that could be used on a whole range of surfaces, opening up the horizons of holographic applications." The research is published in the journal Nature Communications (DOI 10.1038/NCOMMS15354) on 18 May.


The technique involves projecting a grayscale pattern of light and dark shapes onto a thin layer of liquid acrylate polymer placed in a plate or between two glass slides. A photoinitiator material mixed into the polymer initiates a crosslinking reaction when struck by light from an ordinary LED projector, causing a solid film to form. A light-absorbing dye in the polymer serves as a regulator for the light. Due to the complicated interaction between the evolution of the polymer network and volume shrinkage during photo curing, areas of the polymer that receive less light exhibit more apparent bending behavior. When the newly-created polymer film is removed from the liquid polymer, the stress created in the film by the differential shrinkage causes the folding to begin. To make the most complex origami structures, the researchers shine light onto both sides of the structures. Origami structures produced so far include tiny tables, capsules, flowers, birds and the traditional miura-ori fold—all about a half-inch in size. The origami structures could have applications in soft robots, microelectronics, soft actuators, mechanical metamaterials and biomedical devices. "The basic idea of our method is to utilize the volume shrinkage phenomenon during photo-polymerization," said Jerry Qi, a professor in the Woodruff School of Mechanical Engineering at Georgia Tech. "During a specific type of photopolymerization, frontal photopolymerization, the liquid resin is cured continuously from the side under light irradiation toward the inner side. This creates a non-uniform stress field that drives the film to bend along the direction of light path." Details of the work are scheduled to be published April 28 in the journal Science Advances. The research was supported by the National Science Foundation, the Air Force Office of Scientific Research and the Chinese Scholarship Council. It is believed to be the first application to create self-folding origami structures through the control of volume shrinkage during patterned photopolymerization. The process that creates the shrinkage phenomenon is considered harmful in other uses of the polymer. "Volume shrinkage of polymer was always assumed to be detrimental in the fabrication of composites and in the conventional 3-D printing technology," said Daining Fang, a co-author of the paper and a professor at Peking University when the research was done. "Our work shows that with a change of perspective, this phenomenon can become quite useful." Fang is now at Beijing Institute of Technology. To make the most complex shapes with bending in both directions, the researchers can flip the patterned film over to create crosslinking on the other side. "We have developed two types of fabrication processes," said Zeang Zhao, a Ph.D. student at Georgia Tech and Peking University. "In the first one, you can just shine the light pattern towards a layer of liquid resin, and then you will get the origami structure. In the second one, you may need to flip the layer and shine a second pattern. This second process gives you much wider design freedom." Light is shined onto the film for five to ten seconds, which produces a film about 200 microns thick. "The areas that receive light become solid; the other parts of the pattern remain liquid, and the structure can then be removed from the liquid polymer," said Qi. "The technique is very simple." Frontal photopolymerization is a process in which a polymer film is continuously cured from one side in a thick layer of liquid resin. In the presence of strong light attenuation, the solidification front initiates at the surface upon illumination and propagates toward the liquid side as the irradiation time increases. The process can be delicately tuned by controlling the illumination time and the light intensity, and the method has been used to fabricate microfluidic devices and synthesize microparticles. The researchers used poly(ethylene glycol) diacrylate in this demonstration, but the technique should work with a broad range of photocurable polymers. An orange dye was used in the demonstration, but other dyes could produce structures in a range of different colors. For the proof-of-principle, Zhao created a PowerPoint pattern by hand. To scale the process up, the system could be connected to a computer-aided design (CAD) tool for generating more precise grayscale patterns. Qi believes the technique could be used to produce structures as much as an inch in size. "The self-folding requires relatively thin films which might not be possible in larger structures," he said. Added Qi, "We have developed a simple approach to fold a thin sheet of polymer into complicated three-dimensional origami structures. Our approach is not limited by specific materials, and the patterning is so simple that anybody with PowerPoint and a projector could do it." More information: "Origami by frontal photopolymerization," Science Advances  28 Apr 2017: Vol. 3, no. 4, e1602326 DOI: 10.1126/sciadv.1602326, http://advances.sciencemag.org/content/3/4/e1602326


News Article | April 28, 2017
Site: www.eurekalert.org

Researchers at the Georgia Institute of Technology and Peking University have found a new use for the ubiquitous PowerPoint slide: Producing self-folding three-dimensional origami structures from photocurable liquid polymers. The technique involves projecting a grayscale pattern of light and dark shapes onto a thin layer of liquid acrylate polymer placed in a plate or between two glass slides. A photoinitiator material mixed into the polymer initiates a crosslinking reaction when struck by light from an ordinary LED projector, causing a solid film to form. A light-absorbing dye in the polymer serves as a regulator for the light. Due to the complicated interaction between the evolution of the polymer network and volume shrinkage during photo curing, areas of the polymer that receive less light exhibit more apparent bending behavior. When the newly-created polymer film is removed from the liquid polymer, the stress created in the film by the differential shrinkage causes the folding to begin. To make the most complex origami structures, the researchers shine light onto both sides of the structures. Origami structures produced so far include tiny tables, capsules, flowers, birds and the traditional miura-ori fold -- all about a half-inch in size. The origami structures could have applications in soft robots, microelectronics, soft actuators, mechanical metamaterials and biomedical devices. "The basic idea of our method is to utilize the volume shrinkage phenomenon during photo-polymerization," said Jerry Qi, a professor in the Woodruff School of Mechanical Engineering at Georgia Tech. "During a specific type of photopolymerization, frontal photopolymerization, the liquid resin is cured continuously from the side under light irradiation toward the inner side. This creates a non-uniform stress field that drives the film to bend along the direction of light path." Details of the work are scheduled to be published April 28 in the journal Science Advances. The research was supported by the National Science Foundation, the Air Force Office of Scientific Research and the Chinese Scholarship Council. It is believed to be the first application to create self-folding origami structures through the control of volume shrinkage during patterned photopolymerization. The process that creates the shrinkage phenomenon is considered harmful in other uses of the polymer. "Volume shrinkage of polymer was always assumed to be detrimental in the fabrication of composites and in the conventional 3-D printing technology," said Daining Fang, a co-author of the paper and a professor at Peking University when the research was done. "Our work shows that with a change of perspective, this phenomenon can become quite useful." Fang is now at Beijing Institute of Technology. To make the most complex shapes with bending in both directions, the researchers can flip the patterned film over to create crosslinking on the other side. "We have developed two types of fabrication processes," said Zeang Zhao, a Ph.D. student at Georgia Tech and Peking University. "In the first one, you can just shine the light pattern towards a layer of liquid resin, and then you will get the origami structure. In the second one, you may need to flip the layer and shine a second pattern. This second process gives you much wider design freedom." Light is shined onto the film for five to ten seconds, which produces a film about 200 microns thick. "The areas that receive light become solid; the other parts of the pattern remain liquid, and the structure can then be removed from the liquid polymer," said Qi. "The technique is very simple." Frontal photopolymerization is a process in which a polymer film is continuously cured from one side in a thick layer of liquid resin. In the presence of strong light attenuation, the solidification front initiates at the surface upon illumination and propagates toward the liquid side as the irradiation time increases. The process can be delicately tuned by controlling the illumination time and the light intensity, and the method has been used to fabricate microfluidic devices and synthesize microparticles. The researchers used poly(ethylene glycol) diacrylate in this demonstration, but the technique should work with a broad range of photocurable polymers. An orange dye was used in the demonstration, but other dyes could produce structures in a range of different colors. For the proof-of-principle, Zhao created a PowerPoint pattern by hand. To scale the process up, the system could be connected to a computer-aided design (CAD) tool for generating more precise grayscale patterns. Qi believes the technique could be used to produce structures as much as an inch in size. "The self-folding requires relatively thin films which might not be possible in larger structures," he said. Added Qi, "We have developed a simple approach to fold a thin sheet of polymer into complicated three-dimensional origami structures. Our approach is not limited by specific materials, and the patterning is so simple that anybody with PowerPoint and a projector could do it." This research was supported by NSF awards CMMI-1462894, CMMI-1462895, and EFRI-1435452; and the Air Force Office of Scientific Research grant 15RT0885. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the sponsoring organizations.


Wei H.,Beijing Institute of Technology
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

Recently, Geng et al. proposed to allow a non-minimal coupling between quintessence and gravity in the framework of teleparallel gravity, motivated by the similar one in the framework of General Relativity (GR). They found that this non-minimally coupled quintessence in the framework of teleparallel gravity has a richer structure, and named it "teleparallel dark energy". In the present work, we note that there might be a deep and unknown connection between teleparallel dark energy and Elko spinor dark energy. Motivated by this observation and the previous results of Elko spinor dark energy, we try to study the dynamics of teleparallel dark energy. We find that there exist only some dark-energy-dominated de Sitter attractors. Unfortunately, no scaling attractor has been found, even when we allow the possible interaction between teleparallel dark energy and matter. However, we note that w at the critical points is in agreement with observations (in particular, the fact that w=-1 independently of ξ is a great advantage). © 2012 Elsevier B.V.

Loading Beijing Institute of Technology collaborators
Loading Beijing Institute of Technology collaborators