A new variant of the min-cost bin covering problem (min-cost BCP) has been proposed, in which each item has two parameters, capacity and cost. For the offline min-cost BCP, we have presented an algorithm C-FF1. It has...
详细信息
A new variant of the min-cost bin covering problem (min-cost BCP) has been proposed, in which each item has two parameters, capacity and cost. For the offline min-cost BCP, we have presented an algorithm C-FF1. It has been proved that the C-FF1 algorithm has an asymptotic worst-case performance ratio of 1/2. For the online min-cost BCP, we have also presented an online algorithm C-FF2 with an absolute worst-case ratio 1/2. Moreover, we have provided lower worst-case bounds of any online and offline algorithms.
The isothermal phase diagram of the Cu2O-Al2O3-SiO2 ternary system at 1150℃ was reported for the samples which were prepared from sol-gel method and quenched by water after being heated at 1150℃ for 12 h. Based on t...
详细信息
The isothermal phase diagram of the Cu2O-Al2O3-SiO2 ternary system at 1150℃ was reported for the samples which were prepared from sol-gel method and quenched by water after being heated at 1150℃ for 12 h. Based on the conventional X-ray powder diffraction （XRD） and in situ high-temperature XRD quantitative analysis,in addition to scanning electron microscopy measurement,the phase identification was achieved. Combining the deduction from the component phase diagrams of the binary systems using the phase equilibrium theorem,the primary isothermal phase diagram was plotted over the composition area Cu2O-mullite-SiO2. In this area,the approximate composition areas of two two-phase regions and one three-phase region,（L2＋Cr）,（L2＋M）,and （L1＋L2＋Tr）,were determined. Moreover,the precise composition areas of both of the three-phase regions （L2＋Cr＋M） and （L2＋M＋A） were determined according to the results of conventional and in situ high-temperature XRD quantitative analysis by Rietveld method.
A promising catalyst, KNaY was prepared by an ion exchange method with aqueous potassium chloride solution, Compared with NaY, KNaY was an effective catalyst for the dehydration of methyl lactate to methyl acrylate. U...
详细信息
A promising catalyst, KNaY was prepared by an ion exchange method with aqueous potassium chloride solution, Compared with NaY, KNaY was an effective catalyst for the dehydration of methyl lactate to methyl acrylate. Under the optimized conditions, an improved yield of 37.9 mol% was achieved.
Reentrant impulse in the myocardium is considered to be a major factor promoting electrophysiological abnormalities or even leading to ventricular tachycardias (VTs) and ventricular fibrillations (VFs). Tip trajectory...
详细信息
Reentrant impulse in the myocardium is considered to be a major factor promoting electrophysiological abnormalities or even leading to ventricular tachycardias (VTs) and ventricular fibrillations (VFs). Tip trajectory of the reentrant wave can reflect stability of the electrical propagation and area of the reentrant movement, thereby being considered as one of the most concerned parameters in studying electrical activities during VT/VF. The purpose of the present study is to propose a practical method to find out tip trajectories using a computational approach. In this study Luo-Rudy 1991 mathematical model of the ventricular cell was used. The operator splitting method was utilized to integrate the partial differential equations in the two-dimensional tissue. And spiral waves were initiated by the cut wave front technique. Through experiments we found it was difficult to find out the tips by finding intersection of the two isovoltage lines as proposed in most papers. Therefore, we suggested that tip points were detected by seeking the shortest distance of the two adjacent isovoltage contour lines. The results showed that tip trajectories of these spiral waves found in our way were very near to the tips observed, implying validation of our method in measuring tip trajectories in cardiac reentry.
Porous sol-gel glass of CaO-SiO2-P2O5 system with macropores larger than 100 μm was prepared by adding stearic acid as pore former when the sintering was carried out at 700 ℃ for *** sol-gel porous glass shows an am...
详细信息
Porous sol-gel glass of CaO-SiO2-P2O5 system with macropores larger than 100 μm was prepared by adding stearic acid as pore former when the sintering was carried out at 700 ℃ for *** sol-gel porous glass shows an amorphous structure. The diameter of the pore created by pore former varies from 100 to 300 μm, and macroporous glass has a narrow and small pore size distribution in mesoporous scale. The porosity and pore size of macroporous bioactive glass can be controlled.
Discrete chaotic systems are used for bi-directlonal secure communication. Both sides of communication keep sending signals to achieve their synchronization, and then recover the messages. However, the third side with...
详细信息
Discrete chaotic systems are used for bi-directlonal secure communication. Both sides of communication keep sending signals to achieve their synchronization, and then recover the messages. However, the third side without keys cannot get useful information. Known-plaintext attack is also engaged to analyze this method, and the simulation results show that the proposed method can reach high security performance.
Control parameters of original differential evolution （DE） are kept fixed throughout the entire evolutionary process. However, it is not an easy task to properly set control parameters in DE for different optiinizat...
详细信息
Control parameters of original differential evolution （DE） are kept fixed throughout the entire evolutionary process. However, it is not an easy task to properly set control parameters in DE for different optiinization problems. According to the relative position of two different individual vectors selected to generate a difference vector in the searching place, a self-adapting strategy for the scale factor F of the difference vector is proposed. In terms of the convergence status of the target vector in the current population, a self-adapting crossover probability constant CR strategy is proposed. Therefore, good target vectors have a lower CFI while worse target vectors have a large CFI. At the same time, the mutation operator is modified to improve the convergence speed. The performance of these proposed approaches are studied with the use of some benchmark problems and applied to the trajectory planning of a three-joint redundant manipulator. Finally, the experiment results show that the proposed approaches can greatly improve robustness and convergence speed.
The fact that outburst traffic in industrial Ethemet was focused on that would bring self-similar phenomenon leading to the delay increase of the cyclical data, and a hybrid priority queue schedule model was proposed ...
详细信息
The fact that outburst traffic in industrial Ethemet was focused on that would bring self-similar phenomenon leading to the delay increase of the cyclical data, and a hybrid priority queue schedule model was proposed in which the outburst data was given the highest priority. Some properties of the self-similar outburst data were proved by network calculus, and its service curve scheduled by the switch was gained. And then the performance of the scheduling algorithm was obtained. The simulation results are close to those calculated by using network calculus model. Some results are of actual significance to the construction of switched industrial Ethernet.
A two-stage process has been developed to generate the silica-based macromonomer through surface-modification of silica with polymerizable vinyl groups. The silica surfaces were treated with excess 2,4-toluene diisocy...
详细信息
A two-stage process has been developed to generate the silica-based macromonomer through surface-modification of silica with polymerizable vinyl groups. The silica surfaces were treated with excess 2,4-toluene diisocynate (TDI), after which the residual isocyanate groups were converted into polymerizable vinyl groups by reaction with hydroxypropylacrylate (HPA). Thus, polystyrene/silica nanocomposites were prepared by conventional radical copolymerization of styrene with silica macromonomer. The main effecting factors, such as ratios of styrene to the macromonomer, together with polymerization time on the copolymerization were studied in detail. FTIR, DSC and TGA were utilized to characterize the nanocomposites. Experimental results revealed that the silica nanoparticles act as cross-linking points in the polystytene/silica nanocomposites, and the glass transition temperatures of the nanocomposites are higher than that of the corresponding pure polystyrene. The glass transition temperatures of nanocomposites increased with the increasing of silica contents, which were further ascertained by DSC.
The polyamide 6(PA6)/SiO_(2) nanocomposites were prepared by in situ polymerization and the rheological behaviors were *** morphology of resultant materials was characterized by scanning electron microscopy(SEM)and th...
详细信息
The polyamide 6(PA6)/SiO_(2) nanocomposites were prepared by in situ polymerization and the rheological behaviors were *** morphology of resultant materials was characterized by scanning electron microscopy(SEM)and the rheological behaviors were characterized by capillary *** results showed that the SiO_(2) particle size was around 50 nm and the particles dispersed evenly in PA6 *** nanocomposites were pesudoplastic fluids and the apparent viscosities of nanocomposites increased initially and then decreased with the increase in nano-SiO_(2) content at the same *** non-Newtonian indexes of nanocomposites were smaller than those of pure *** the increase in nano-SiO_(2) content the apparent viscous activation energies of nanocomposites increased initially and then *** rheological behaviors revealed that there were strong interactions between PA6 macromolecule chains and nano-SiO_(2) particles.
暂无评论