After gas drainage,the outburst seam is dry and,consequently,during subsequent mechanized mining,unwanted dust production is extensive.Because the hard dustfall typically has a small particle size it contains a high p...After gas drainage,the outburst seam is dry and,consequently,during subsequent mechanized mining,unwanted dust production is extensive.Because the hard dustfall typically has a small particle size it contains a high percentage of respirable dust.Considering these factors,this paper improved the efficiency of dustfall by reducing the surface tension of the liquid used as a wetting agent,then configuring five kinds of wetting agents by adopting various doses and types of surfactants,neutral inorganic salts and chemical additives,etc.After purchasing DA-85 and SRJ-1 wetting agent,the surface tension and critical micelle concentration of seven kinds of wetting agents were measured using the capillary rise method.Wetting agent A was confirmed to have the best comprehensive effect.The experiments were optimized by measuring and comparatively analyzing contact angles of pure water,SRJ-1 wetting agent and wetting agent A on the surface of different coal samples using a contact angle measurement instrument(HARKESPCA).By comparative analysis,dust-proof effects of seam,dynamic pressure water infusion and highpressure spray in the tunneling face at the Daning coal mine using pure water,wetting agent SRJ-1and A,it was determined that after using wetting agent A,the average dust concentration in the place of the mining machine driver,10 m and 110 m away from the tunneling front is approximately 300 mg/m^3,240 mg/m^3 and 100 mg/m^3,respectively.This practice increased the dust-proof efficiency dramatically and achieved a good comprehensive dust-proof effect.展开更多
This scientific paper is a comparative analysis of two mathematical conjectures. The newly proposed -3(-n) - 1 Remer conjecture and how it is related to and a proof of the more well known 3n + 1 Collatz conjecture. An...This scientific paper is a comparative analysis of two mathematical conjectures. The newly proposed -3(-n) - 1 Remer conjecture and how it is related to and a proof of the more well known 3n + 1 Collatz conjecture. An overview of both conjectures and their respective iterative processes will be presented. Showcasing their unique properties and behavior to each other. Through a detailed comparison, we highlight the similarities and differences between these two conjectures and discuss their significance in the field of mathematics. And how they prove each other to be true.展开更多
Effect of dust charge fluctuations on Kelvin-Helmholtz (K-H) instability driven by sheared dust flow is investigated in magnetised three-component cold dusty plasma. It is found that the dust charge fluctuations have ...Effect of dust charge fluctuations on Kelvin-Helmholtz (K-H) instability driven by sheared dust flow is investigated in magnetised three-component cold dusty plasma. It is found that the dust charge fluctuations have little effect on the tenuous dust plasma in low-frequency perturbation. For a dense dust plasma, the maximum damping rate of the perturbed wave due to dust charge fluctuations will reach the order of dusty charging frequency. It will affect the existence of the K-H instability in the long wave length perturbation.展开更多
Based upon broad-band CCD observation data of comet Hale-Bopp obtained by a 60cm telescope at Xinglong Station of Beijing Astronomical Observatory during March-August, 1996, the photometric results of comet Hale-Bopp ...Based upon broad-band CCD observation data of comet Hale-Bopp obtained by a 60cm telescope at Xinglong Station of Beijing Astronomical Observatory during March-August, 1996, the photometric results of comet Hale-Bopp are reported. Using the photometric results, the dust production rate, radius and mass of nucleus of comet Hale-Bopp are estimated as follows: dM/dt～1.5×10 5 kgs -1, R n～35.5km, and M n～5.65×10 16kg.展开更多
The three measurement periods: the TOMS Nimbus-7 TOMSN7L3 v008 from 1978 to 1993, the TOMS EP TOMSEPL3 v008 from 1996 to 2005 and the OMI OMTO3d v003 from 2004 to 2008 have allowed the presence of dust to be observed ...The three measurement periods: the TOMS Nimbus-7 TOMSN7L3 v008 from 1978 to 1993, the TOMS EP TOMSEPL3 v008 from 1996 to 2005 and the OMI OMTO3d v003 from 2004 to 2008 have allowed the presence of dust to be observed in the 10°North to 20°North latitudinal band (10 - 20 band) of Africa. The 10 - 20 band has a permanent dust presence. The AERONET data show AOD peaks exceeding 2 in Senegal and Niger (on an AOD scale). The statistical study reveals intra-annual relationships in deposition. In Senegal, a significant deposition is observed.展开更多
The equilibrium potential of fluffy dust grains in plasma are calculated for comet P/Halley and comet P/G-Z. It is found that the dust equilibrium potential linearly correlates with the logarithm of electron density. ...The equilibrium potential of fluffy dust grains in plasma are calculated for comet P/Halley and comet P/G-Z. It is found that the dust equilibrium potential linearly correlates with the logarithm of electron density. We propose this relationship can also be applied to comet Hale-Bopp.展开更多
The equilibrium potential and dust fragmentation criterion of fluffy dust grains in plasma are calculated for comet P/Halley . It is found that the dust grain acquires its largest negative potential and disruptive pro...The equilibrium potential and dust fragmentation criterion of fluffy dust grains in plasma are calculated for comet P/Halley . It is found that the dust grain acquires its largest negative potential and disruptive probability about 50,000km from the comet where the dust mass spectrum measured by the spacecraft took a great change.展开更多
The observed linear polarization data of comet Hyakutake are studied at wavelengths λ=0.365 μm,λ=0.485 μm and 0.684μm through simulations using Ballistic Particle-Cluster Aggregate and Ballistic Cluster-Cluster A...The observed linear polarization data of comet Hyakutake are studied at wavelengths λ=0.365 μm,λ=0.485 μm and 0.684μm through simulations using Ballistic Particle-Cluster Aggregate and Ballistic Cluster-Cluster Aggregate aggregates of 128 spherical monomers.We first found that the size parameter of the monomer,x ～ 1.56-1.70,turned out to be the most suitable which provides the best fits to the observed dust scattering properties at three wavelengths：λ=0.365 μm,0.485μm and 0.684μm.Thus,the effective radius of the aggregate （r） lies in the range 0.45 μm ≤ r ≤ 0.49 μm at λ=0.365 μm;0.60 μm ≤ r ≤ 0.66 μm at λ=0.485 μm and 0.88 μm ≤ r ≤ 0.94 μm at λ=0.684 μm.Now using superposition T-MATRIX code and the power-law size distribution,n（r） ～ r-3,the best-fitting values of complex refractive indices are calculated for the observed polarization data at the above three wavelengths.The best-fitting complex refractive indices （n,k） are found to be （1.745,0.095） at λ=0.365 μm,（1.743,0.100） at λ=0.485 μm and （1.695,0.100） at λ=0.684 μm.The refractive indices derived from the present analysis correspond to a mixture of both silicates and organics,which are in good agreement with the in situ measurement of comets by different spacecraft.展开更多
An observational result from March 12 to April 15 for comet Hale-Bopp is given in this paper. During this period a fan-shaped erupted region with angular extent of about 100 degrees near the nucleus was seen continual...An observational result from March 12 to April 15 for comet Hale-Bopp is given in this paper. During this period a fan-shaped erupted region with angular extent of about 100 degrees near the nucleus was seen continually. In addition, a shell structure with at most 5 layers often appeared. It is found that these layers were equal-spaced with a distance of about 2×10 4 km and were moving outward with a speed of about 35 m/s. It is suggested that this phenomenon was possibly a kind of wave created by charged attogram dust grains erupted from the nucleus, which collided with either the solar wind or material of the coma. The propagation period of the wave was about 6 days but the spin of the Comet Hale-Bopp could be very slow and the period was about 3 yr. This spin movement had the opposite direction as its orbital motion.展开更多
基金partly supported by the National Natural Science Foundation of China (No.51404263)the National Natural Science Foundation of Jiangsu Province (No.BK20130203)+3 种基金the Coal Mine Joint Funds of the National Natural Science Foundation of China (No.51134023)the State Key Laboratory Cultivation Base for Gas Geology and Gas Control (No.WS2013A05)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)the independent study for State Key Laboratory of Coal Resources and Safe Mining,China University of Mining and Technology (No.SKLCRSM09X04)
文摘After gas drainage,the outburst seam is dry and,consequently,during subsequent mechanized mining,unwanted dust production is extensive.Because the hard dustfall typically has a small particle size it contains a high percentage of respirable dust.Considering these factors,this paper improved the efficiency of dustfall by reducing the surface tension of the liquid used as a wetting agent,then configuring five kinds of wetting agents by adopting various doses and types of surfactants,neutral inorganic salts and chemical additives,etc.After purchasing DA-85 and SRJ-1 wetting agent,the surface tension and critical micelle concentration of seven kinds of wetting agents were measured using the capillary rise method.Wetting agent A was confirmed to have the best comprehensive effect.The experiments were optimized by measuring and comparatively analyzing contact angles of pure water,SRJ-1 wetting agent and wetting agent A on the surface of different coal samples using a contact angle measurement instrument(HARKESPCA).By comparative analysis,dust-proof effects of seam,dynamic pressure water infusion and highpressure spray in the tunneling face at the Daning coal mine using pure water,wetting agent SRJ-1and A,it was determined that after using wetting agent A,the average dust concentration in the place of the mining machine driver,10 m and 110 m away from the tunneling front is approximately 300 mg/m^3,240 mg/m^3 and 100 mg/m^3,respectively.This practice increased the dust-proof efficiency dramatically and achieved a good comprehensive dust-proof effect.
文摘This scientific paper is a comparative analysis of two mathematical conjectures. The newly proposed -3(-n) - 1 Remer conjecture and how it is related to and a proof of the more well known 3n + 1 Collatz conjecture. An overview of both conjectures and their respective iterative processes will be presented. Showcasing their unique properties and behavior to each other. Through a detailed comparison, we highlight the similarities and differences between these two conjectures and discuss their significance in the field of mathematics. And how they prove each other to be true.
文摘Effect of dust charge fluctuations on Kelvin-Helmholtz (K-H) instability driven by sheared dust flow is investigated in magnetised three-component cold dusty plasma. It is found that the dust charge fluctuations have little effect on the tenuous dust plasma in low-frequency perturbation. For a dense dust plasma, the maximum damping rate of the perturbed wave due to dust charge fluctuations will reach the order of dusty charging frequency. It will affect the existence of the K-H instability in the long wave length perturbation.
文摘Based upon broad-band CCD observation data of comet Hale-Bopp obtained by a 60cm telescope at Xinglong Station of Beijing Astronomical Observatory during March-August, 1996, the photometric results of comet Hale-Bopp are reported. Using the photometric results, the dust production rate, radius and mass of nucleus of comet Hale-Bopp are estimated as follows: dM/dt～1.5×10 5 kgs -1, R n～35.5km, and M n～5.65×10 16kg.
文摘The three measurement periods: the TOMS Nimbus-7 TOMSN7L3 v008 from 1978 to 1993, the TOMS EP TOMSEPL3 v008 from 1996 to 2005 and the OMI OMTO3d v003 from 2004 to 2008 have allowed the presence of dust to be observed in the 10°North to 20°North latitudinal band (10 - 20 band) of Africa. The 10 - 20 band has a permanent dust presence. The AERONET data show AOD peaks exceeding 2 in Senegal and Niger (on an AOD scale). The statistical study reveals intra-annual relationships in deposition. In Senegal, a significant deposition is observed.
基金theNationalNaturalScienceFoundationofChinaUnderGrant (No .199730 18& 196 5 30 0 1)
文摘The equilibrium potential of fluffy dust grains in plasma are calculated for comet P/Halley and comet P/G-Z. It is found that the dust equilibrium potential linearly correlates with the logarithm of electron density. We propose this relationship can also be applied to comet Hale-Bopp.
基金theNationalNaturalScienceFoundationofChina (No .196 5 30 0 1)
文摘The equilibrium potential and dust fragmentation criterion of fluffy dust grains in plasma are calculated for comet P/Halley . It is found that the dust grain acquires its largest negative potential and disruptive probability about 50,000km from the comet where the dust mass spectrum measured by the spacecraft took a great change.
文摘The observed linear polarization data of comet Hyakutake are studied at wavelengths λ=0.365 μm,λ=0.485 μm and 0.684μm through simulations using Ballistic Particle-Cluster Aggregate and Ballistic Cluster-Cluster Aggregate aggregates of 128 spherical monomers.We first found that the size parameter of the monomer,x ～ 1.56-1.70,turned out to be the most suitable which provides the best fits to the observed dust scattering properties at three wavelengths：λ=0.365 μm,0.485μm and 0.684μm.Thus,the effective radius of the aggregate （r） lies in the range 0.45 μm ≤ r ≤ 0.49 μm at λ=0.365 μm;0.60 μm ≤ r ≤ 0.66 μm at λ=0.485 μm and 0.88 μm ≤ r ≤ 0.94 μm at λ=0.684 μm.Now using superposition T-MATRIX code and the power-law size distribution,n（r） ～ r-3,the best-fitting values of complex refractive indices are calculated for the observed polarization data at the above three wavelengths.The best-fitting complex refractive indices （n,k） are found to be （1.745,0.095） at λ=0.365 μm,（1.743,0.100） at λ=0.485 μm and （1.695,0.100） at λ=0.684 μm.The refractive indices derived from the present analysis correspond to a mixture of both silicates and organics,which are in good agreement with the in situ measurement of comets by different spacecraft.
文摘An observational result from March 12 to April 15 for comet Hale-Bopp is given in this paper. During this period a fan-shaped erupted region with angular extent of about 100 degrees near the nucleus was seen continually. In addition, a shell structure with at most 5 layers often appeared. It is found that these layers were equal-spaced with a distance of about 2×10 4 km and were moving outward with a speed of about 35 m/s. It is suggested that this phenomenon was possibly a kind of wave created by charged attogram dust grains erupted from the nucleus, which collided with either the solar wind or material of the coma. The propagation period of the wave was about 6 days but the spin of the Comet Hale-Bopp could be very slow and the period was about 3 yr. This spin movement had the opposite direction as its orbital motion.
