Dear Editor,This letter investigates the problem of multi-dimension formation tracking(MDFT)for the cross-domain unmanned systems,including several interconnected agents,namely,unmanned aerial vehicles(UAVs)and unmann...Dear Editor,This letter investigates the problem of multi-dimension formation tracking(MDFT)for the cross-domain unmanned systems,including several interconnected agents,namely,unmanned aerial vehicles(UAVs)and unmanned surface vehicles(USVs).We assume that each agent suffers from by the mixed constraints on its velocity,control input and Euler angle.Solving the MDFT problem implies that 1)The virtual state of each USV is determined in the earth coordinate by expanding its 2D work space to the 3D space.展开更多
North and west China has abundant coal resources, however, such resources make these regions prone to serious mine fire disasters. Although the copious sand and fly ash resources found in these areas can be used as fi...North and west China has abundant coal resources, however, such resources make these regions prone to serious mine fire disasters. Although the copious sand and fly ash resources found in these areas can be used as fire-fighting materials, conventional grouting is expensive because of water shortage and loess particles. A new compound material(i.e., a sand-suspended colloid), which comprises a mineral inorganic gel and an organic polymer, is developed in the current study to improve the quality of sand injection and reduce water wastage when grouting. The new material can steadily suspend the sand, through the addition of a small amount of colloid yielding steady sand-suspended slurry. The process of producing the slurry is convenient and quick, overcoming the shortage of sand-suspending thickeners which need heat and are difficult to produce. The space work model based on the theory of the double-electric layer is established to study the suspended mechanism of the solid particles in the sand-suspended colloid.The dispersion effect of the sand-suspended colloid is demonstrated by the incorporation of the electrostatic effect by the double-electric layer and the steric hindrance effect on the sand particles, ensuring the stability of the colloid system and the steady suspension of sand particles in the sand-suspended colloid.Mechanical analysis indicates that the sand is suspended steadily under the condition that the rock sand particles stress on the lower part of the fluid is less than the yield stress of the colloid. Finally, the fireprevention technology of sand suspension was applied and tested in the Daliuta Coal Mine, achieving successful results.展开更多
Scientists from Zhejiang University have developed a new kind of self-cleaning glass. It uses electric fields to remove dust and dirt, changing how we keep our living and working spaces clean. This groundbreaking inve...Scientists from Zhejiang University have developed a new kind of self-cleaning glass. It uses electric fields to remove dust and dirt, changing how we keep our living and working spaces clean. This groundbreaking invention marks a significant advancement in the field of materials science and has the potential to reshape various industries, ranging from construction to automotive sector, with its great benefits.展开更多
基金supported in part by the National Natural Science Foundation of China(62073301,62373162,62473349,U24A20268,62233007)the Shenzhen Science and Technology Program(JCYJ20240813114007010).
文摘Dear Editor,This letter investigates the problem of multi-dimension formation tracking(MDFT)for the cross-domain unmanned systems,including several interconnected agents,namely,unmanned aerial vehicles(UAVs)and unmanned surface vehicles(USVs).We assume that each agent suffers from by the mixed constraints on its velocity,control input and Euler angle.Solving the MDFT problem implies that 1)The virtual state of each USV is determined in the earth coordinate by expanding its 2D work space to the 3D space.
基金support of the research funds provided by the National Natural Science Foundation of China (Nos. 51304071, 51304073)the Open Projects of State Key Laboratory of Coal Resources and Safe Mining, China University of Mining & Technology of China (No. 12KF02)
文摘North and west China has abundant coal resources, however, such resources make these regions prone to serious mine fire disasters. Although the copious sand and fly ash resources found in these areas can be used as fire-fighting materials, conventional grouting is expensive because of water shortage and loess particles. A new compound material(i.e., a sand-suspended colloid), which comprises a mineral inorganic gel and an organic polymer, is developed in the current study to improve the quality of sand injection and reduce water wastage when grouting. The new material can steadily suspend the sand, through the addition of a small amount of colloid yielding steady sand-suspended slurry. The process of producing the slurry is convenient and quick, overcoming the shortage of sand-suspending thickeners which need heat and are difficult to produce. The space work model based on the theory of the double-electric layer is established to study the suspended mechanism of the solid particles in the sand-suspended colloid.The dispersion effect of the sand-suspended colloid is demonstrated by the incorporation of the electrostatic effect by the double-electric layer and the steric hindrance effect on the sand particles, ensuring the stability of the colloid system and the steady suspension of sand particles in the sand-suspended colloid.Mechanical analysis indicates that the sand is suspended steadily under the condition that the rock sand particles stress on the lower part of the fluid is less than the yield stress of the colloid. Finally, the fireprevention technology of sand suspension was applied and tested in the Daliuta Coal Mine, achieving successful results.
文摘Scientists from Zhejiang University have developed a new kind of self-cleaning glass. It uses electric fields to remove dust and dirt, changing how we keep our living and working spaces clean. This groundbreaking invention marks a significant advancement in the field of materials science and has the potential to reshape various industries, ranging from construction to automotive sector, with its great benefits.
