A periodic packing mode of trickle-bed reactor (TBR) for the gas limited reaction was proposed. Hy-drogenation of 2-ethylanthraquinone over Pd/Al2O3 in a laboratory-scale TBR was taken as a test reaction for determini...A periodic packing mode of trickle-bed reactor (TBR) for the gas limited reaction was proposed. Hy-drogenation of 2-ethylanthraquinone over Pd/Al2O3 in a laboratory-scale TBR was taken as a test reaction for determining whether the periodic packing mode is advantageous. The effects of operating conditions and packing type on TBR performance were experimentally examined to demonstrate the cause-effect relationships. A mathe-matic model of TBR considering axial dispersion and fractional wetting was developed to quantitatively illuminate the reason of performance enhancement.展开更多
For fragile products,packaging requires cushioning protection to prevent irreversible damage from accidental falls,transportation impacts,and other causes.The new polyurethane foam(PUF)material demonstrates superior c...For fragile products,packaging requires cushioning protection to prevent irreversible damage from accidental falls,transportation impacts,and other causes.The new polyurethane foam(PUF)material demonstrates superior cushioning and vibration isolation performance in practical applications,effectively minimizing damage from vibrations.Drop and vibration experiments were conducted on packages comprising novel PUF,expandable polyethylene,ethylene-vinyl acetate copolymer foam,and bracelets.Results verify that the new PUF material outperforms in cushioning and vibration isolation,as observed from the acceleration response.Furthermore,a random vibration analysis of a packaging unit involving different thicknesses of PUF materials and bracelets reveals the enhanced vibration isolation effect within a specific thickness range.The vibration results of the bracelet’s outer packaging align closely with finite element simulation results,validating the effectiveness of designing and optimizing the outer packaging.Through finite element simulation,deeper understanding and prediction of the bracelet’s vibration response under various conditions is achieved,facilitating optimized packaging design for better protection and vibration damping.展开更多
Both distillation performance and hydrodynamic study for backmixing by tracer technique were carried out in a high-pressure packed column with 0.15 m inner diameter over a wide range of operating conditions. Isobutane...Both distillation performance and hydrodynamic study for backmixing by tracer technique were carried out in a high-pressure packed column with 0.15 m inner diameter over a wide range of operating conditions. Isobutane and n-pentane are employed as test mixture in the distillation experiment and air/water is used for the hydrodynamic study. The column is installed with Mellapak 350Y structured packing and the total packing height is 2.0 m. With the increasing operating pressure, the separation efficiency increases slightly while the F-factor corresponding to the maximum efficiency at each pressure is descending. It is noted that, at all operating pressures, with the increase of F-factor, the packing efficiency is slightly higher up to the flooding point. The application of SRP model to high-pressure distillation gives much lower values of HTUOG than those obtained experimentally. An additional term, the height of mixing unit, is introduced to correct the SRP model and improve its accuracy at high pressure. From the tracer experiments, the height of mixing unit for gas phase was found to be larger than that for the liquid phase. From this viewpoint, it is believed that the gas phase backmixing gives more unfavorable influence on the separation efficiency in comparison with liquid phase.展开更多
A composite composed of waste package poly（vinyl chloride）（WPVC） and organic montmorillonite（OMMT） was prepared by coextrusion, which is used for modifying asphalt. The micromorphology of the WPVC/OMMT composite...A composite composed of waste package poly（vinyl chloride）（WPVC） and organic montmorillonite（OMMT） was prepared by coextrusion, which is used for modifying asphalt. The micromorphology of the WPVC/OMMT composite and its effect on the macroscopic properties of asphalt were studied using a fluorescent microscope and an X-ray diffractometer（XRD）. The introduction of OMMT allows the WPVC to be good dispersed in the asphalt matrix, as demonstrated by differential scanning calorimetry（DSC） and Fourier transform infrared spectroscopy（FTIR） analysis. The results indicate that asphalt modified by WPVC/OMMT composites with low OMMT content results in better high-temperature storage stability and physical properties of modified asphalt.展开更多
The first fit decreasing (FFD) heuristic algorithm is one of the most famous and moststudied methods for an approximative solution of the bin-packing problem. For a list L, letOPT(L) denote the minimal number of bins ...The first fit decreasing (FFD) heuristic algorithm is one of the most famous and moststudied methods for an approximative solution of the bin-packing problem. For a list L, letOPT(L) denote the minimal number of bins into which L can be packed, and let FFD(L)denote the number of bins used by FFD. Johnson showed that for every list L, FFD(L)≤11/9OPT(L)+4. His proof required more than 100 pages. Later, Baker gave a much shorterand simpler proof for FFD(L)≤11/9OPT(L)+3. His proof required 22 pages. In this paper,we give a proof for FFD(L)≤11/9 OPT(L)+1. The proof is much simpler than the previousones.展开更多
Ⅰ. INTRODUCTION Since the last century, a lot of scholars in various fields, including the well-known scientists Woolaston, Thomson (Lord Kelvin) and Bernal were interested in the packing of equal spheres, as it is o...Ⅰ. INTRODUCTION Since the last century, a lot of scholars in various fields, including the well-known scientists Woolaston, Thomson (Lord Kelvin) and Bernal were interested in the packing of equal spheres, as it is of very important significance in theory and practice.展开更多
基金the State Key Development Program for Basic Research of China (No. G2000048005) the SINOPEC (No.X503023).
文摘A periodic packing mode of trickle-bed reactor (TBR) for the gas limited reaction was proposed. Hy-drogenation of 2-ethylanthraquinone over Pd/Al2O3 in a laboratory-scale TBR was taken as a test reaction for determining whether the periodic packing mode is advantageous. The effects of operating conditions and packing type on TBR performance were experimentally examined to demonstrate the cause-effect relationships. A mathe-matic model of TBR considering axial dispersion and fractional wetting was developed to quantitatively illuminate the reason of performance enhancement.
基金the National Natural Science Foundation of China(Grant Numbers 12172151 and 12172149).
文摘For fragile products,packaging requires cushioning protection to prevent irreversible damage from accidental falls,transportation impacts,and other causes.The new polyurethane foam(PUF)material demonstrates superior cushioning and vibration isolation performance in practical applications,effectively minimizing damage from vibrations.Drop and vibration experiments were conducted on packages comprising novel PUF,expandable polyethylene,ethylene-vinyl acetate copolymer foam,and bracelets.Results verify that the new PUF material outperforms in cushioning and vibration isolation,as observed from the acceleration response.Furthermore,a random vibration analysis of a packaging unit involving different thicknesses of PUF materials and bracelets reveals the enhanced vibration isolation effect within a specific thickness range.The vibration results of the bracelet’s outer packaging align closely with finite element simulation results,validating the effectiveness of designing and optimizing the outer packaging.Through finite element simulation,deeper understanding and prediction of the bracelet’s vibration response under various conditions is achieved,facilitating optimized packaging design for better protection and vibration damping.
基金the National Natural Science Foundation of China (No. 20136010).
文摘Both distillation performance and hydrodynamic study for backmixing by tracer technique were carried out in a high-pressure packed column with 0.15 m inner diameter over a wide range of operating conditions. Isobutane and n-pentane are employed as test mixture in the distillation experiment and air/water is used for the hydrodynamic study. The column is installed with Mellapak 350Y structured packing and the total packing height is 2.0 m. With the increasing operating pressure, the separation efficiency increases slightly while the F-factor corresponding to the maximum efficiency at each pressure is descending. It is noted that, at all operating pressures, with the increase of F-factor, the packing efficiency is slightly higher up to the flooding point. The application of SRP model to high-pressure distillation gives much lower values of HTUOG than those obtained experimentally. An additional term, the height of mixing unit, is introduced to correct the SRP model and improve its accuracy at high pressure. From the tracer experiments, the height of mixing unit for gas phase was found to be larger than that for the liquid phase. From this viewpoint, it is believed that the gas phase backmixing gives more unfavorable influence on the separation efficiency in comparison with liquid phase.
基金financial supports from the National Natural Science Foundation of China (Grant Nos. 51172180 and 51372200)Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-12-1045)Local Service Program of Shaanxi Provincial Education Department (Grant No. 2013JC19)
文摘A composite composed of waste package poly（vinyl chloride）（WPVC） and organic montmorillonite（OMMT） was prepared by coextrusion, which is used for modifying asphalt. The micromorphology of the WPVC/OMMT composite and its effect on the macroscopic properties of asphalt were studied using a fluorescent microscope and an X-ray diffractometer（XRD）. The introduction of OMMT allows the WPVC to be good dispersed in the asphalt matrix, as demonstrated by differential scanning calorimetry（DSC） and Fourier transform infrared spectroscopy（FTIR） analysis. The results indicate that asphalt modified by WPVC/OMMT composites with low OMMT content results in better high-temperature storage stability and physical properties of modified asphalt.
文摘The first fit decreasing (FFD) heuristic algorithm is one of the most famous and moststudied methods for an approximative solution of the bin-packing problem. For a list L, letOPT(L) denote the minimal number of bins into which L can be packed, and let FFD(L)denote the number of bins used by FFD. Johnson showed that for every list L, FFD(L)≤11/9OPT(L)+4. His proof required more than 100 pages. Later, Baker gave a much shorterand simpler proof for FFD(L)≤11/9OPT(L)+3. His proof required 22 pages. In this paper,we give a proof for FFD(L)≤11/9 OPT(L)+1. The proof is much simpler than the previousones.
文摘Ⅰ. INTRODUCTION Since the last century, a lot of scholars in various fields, including the well-known scientists Woolaston, Thomson (Lord Kelvin) and Bernal were interested in the packing of equal spheres, as it is of very important significance in theory and practice.
