羊骨基活性炭对溶液中Pb(Ⅱ)的吸附性能

采用本实验室自制的羊骨基活性炭,研究其在不同吸附时间、不同溶液初始浓度、不同投加量、溶液不同的pH值条件下对Pb(Ⅱ)的吸附规律。结果表明:当Pb(Ⅱ)溶液的初始浓度为80mg/L、活性炭投加量为0.10g、吸附时间为6h、溶液温度为45℃时,羊骨基活性炭对Pb(Ⅱ)的去除率高达99%。利用Langmuir吸附等温模型和Freundlich吸附等温模型对其吸附性能的表征得出:羊骨基活性炭对溶液中Pb(Ⅱ)的吸附行为符合Langmuir吸附等温模型和Freundlich吸附等温模型,并且吸附等温曲线在Brunauer五种类型的等温吸附线中比较符合多分子层吸附等温线。     

Determination of optimum processing conditions for hot‐air roasting of hulled sesame seeds using response surface methodology

Sesame paste (tahin) is produced by milling hulled, roasted, sesame seeds. In this study, a hot‐air roasting process for the production of sesame paste was optimised by response surface methodology (RSM) over a range of air temperatures (120–180 °C) for various times (30–60 min). The colour parameters (L, a and b values), browning index (BI), hardness, fracturability and moisture content of the seeds were used as response parameters to develop predictive models and optimise the roasting process. Increases in roasting temperature and time caused increases in the a and b values and in the BI. The hardness and fracturability of seeds also decreased with increasing roasting temperature and time. The quadratic and linear models developed by RSM adequately described the changes in the colour values and textural parameters, respectively. The result of RSM analysis showed that all colour parameters and textural parameters should be used to monitor the roasting of sesame seeds in a hot‐air roaster. To obtain the desired colour and texture, the optimum roasting range for production of sesame paste was determined as 155–170 °C for 40–60 min. Copyright © 2006 Society of Chemical Industry     

Biosorption of lanthanum and cerium from aqueous solutions by Platanus orientalis leaf powder

The biosorption of lanthanum and cerium by leaves powder of Platanus orientalis was separately determined at varying experimental conditions using a batch technique. The effects of initial pH, contact time, initial metal ion concentration and temperature were investigated. The Langmuir and Freundlich isotherms were applied to represent the adsorption process. Langmuir isotherm fits the experimental data quite well. The Langmuir monolayer capacity of the sorbent is 28.65mg g^− 1 and 32.05mg g^− 1 for La and Ce(III), respectively. Thermodynamic parameters such as standard enthalpy (ΔH°), entropy (ΔS°) and free energy (ΔG°) were calculated from the slope and intercept of the plots of lnK_d versus 1/T. The results indicated that sorption was endothermic and spontaneous in nature. The work reveals that powdered leaf of Platanus orientalis is a good choice as a biosorbent for the recovery of lanthanum and cerium from aqueous solution.     

Increasing production rate in U-type assembly lines with sequence-dependent set-up times

U-shaped assembly lines are commonly used in just-in-time production systems as they have some advantages over straight lines. Although maximizing production rates on these lines by assigning tasks to stations is common practice in industrial environments, studies on the stated assembly line balancing problem are limited. This article deals with maximizing the production rate on U-shaped assembly lines under sequence-dependent set-up times. Sequence-dependent set-up times mean that after a task is performed, a set-up time, the duration of which depends on adjacent tasks, is required to start the next task operation. These set-ups are considered by dividing them into two groups, named forward and backward set-ups, to make the problem more practical. Two heuristics based on simulated annealing and genetic algorithms are improved beside the mathematical model. Experimental results show that solving the stated problem using the mathematical model is nearly impossible, while heuristics may obtain solutions that have acceptable deviations from the lower bounds.     

A mass spectrometry method for quantitative and kinetic analysis of gas release from nuclear materials and its application to helium desorption from UO2 and fission gas release from irradiated fuel

A new system has been developed to determine absolute quantities of gas (mainly noble gases) released during thermal desorption in the range from 10^?12 to 10^?5 mol with a precision of few percent. The system is actually designed for simultaneous measurement of gaseous elements like He, Xe, Kr, thermally released from nuclear fuel samples and also allows the determination of the release kinetics as a function of time. This system, called Quantitative GAs MEasurement System (Q-GAMES), is based on the principle of collecting, purifying and spiking the sample gas in a “high-pressure” chamber, and continuous sampling of the gas for mass spectrometric analysis without sample depletion during the experiment. It is equipped with its own spike generator and with different gas purification systems. It is shown that this system fulfills the requirement to work with two existing very high-temperature gas desorption facilities for nuclear materials. This paper describes the Q-GAMES principle, the spiking system, its calibration, its operative mode, the different quantification techniques, as well as its technical data, in combination with some examples of typical application.     

Balancing Multi-Manned Assembly Lines With Walking Workers: Problem Definition,Mathematical Formulation,and an Electromagnetic Field Optimisation Algorithm

Assembly lines are widely used in industrial environments that produce standardised products in high volumes. Multi-manned assembly line is a special version of them that allows simultaneous operation of more than one worker at the same workstation. These lines are widely used in large-sized product manufacturing since they have many advantages over the simple one. This article has dealt with multi-manned assembly line balancing problem with walking workers for minimising the number of workers and workstations as the first and second objectives, respectively. A linear mixed-integer programming formulation of the problem has been firstly addressed after the problem definition is given. Besides that, a metaheuristic based on electromagnetic field optimisation algorithm has been improved. In addition to the classical electromagnetic field optimisation algorithm, a regeneration strategy has been applied to enhance diversification. A particle swarm optimisation algorithm from assembly line balancing literature has been modified to compare with the proposed algorithm. A group of test instances from many precedence diagrams were generated for evaluating the performances of all solution methods. Deviations from lower bound values of the number of workers/workstations and the number of optimal solutions obtained by these methods are concerned as performance criteria. The results obtained by the proposed programming formulations have been also compared with the solutions obtained by the traditional mathematical model of the multi-manned assembly line. Through the experimental results, the performance of the metaheuristic has been found very satisfactory according to the number of obtained optimal solutions and deviations from lower bound values.     

A priority rule-based constructive heuristic and an improvement method for balancing assembly lines with parallel multi-manned workstations

Assembly lines of big-size products such as buses, trucks and helicopters are very different from the lines studied in the literature. These products’ manufacturing processes have a lot of tasks most of which have long task times. Since traditional assembly line models including only one worker in each station (i.e. simple assembly lines) or at most two workers (two-sided assembly lines) may not be suitable for manufacturing these type of products, they need much larger shop floor for a number of stations and long product flow times. In this study, an assembly line balancing problem (ALBP) with parallel multi-manned stations is considered. Following the problem definition, a mixed integer programming formulation is developed. A detailed study of priority rules for simple ALBPs is also presented, and a new efficient constructive heuristic algorithm based on priority rules is proposed. In order to improve solutions found by the constructive heuristic, a genetic algorithm-based solution procedure is also presented. Benchmark instances in the literature are solved by using the proposed mathematical programming formulation. It has been seen that only some of the small-size instances can be solved optimally by this way. So the efficiency of the proposed heuristic method is verified in small-size instances whose optimal solutions are found. For medium- and big-size instances, heuristics’ results and CPU times are demonstrated. A comparative evaluation with a branch and bound algorithm that can be found in the literature is also carried out, and results are presented.     

新疆棉杆基生物油的组成及其结构性能分析

以棉杆为原料,N2作保护气,用管式热解炉对棉杆进行热解的生物油进行成分分析及结构性能分析。用酸度计、毛细管粘度计、石油产品的水分试验器、热重分析(TG-DTG)来确定生物油的结构性能。用红外分析(IR)、气质联用(GC-MS)确定其组分。制备的生物油的水含量2%、pH为3.88、密度为1013.9 kg/m3、运动粘度为2.114 mm2/s;由热重分析结果可知:生物油在140~200℃左右发生一次重量突变,温度200℃以上时达到稳定状态;用红外分析检测出生物油主要有羟基O-H、C=C、C-H、C-O、C=O等官能团;通过GC-MS分析确定的生物油的主要成分包括酸、醇、醛、酮、酚、醚、酯、含氮化合物以及各种复杂的多官能团有机物和少量的含氟、硼、硫、碘的化合物。     

Optimization of removal of lead from bearing-lead anode slime

An optimization process is conducted by the Taguchi experimental design method for removal of lead from decopperized anode slime in aqueous Na₂CO₃/HNO₃ media. The effects of parameters such as reaction temperature, Na₂CO₃ concentration, solid–liquid ratio and reaction period on the conversion are studied. It is seen that the most important parameters affecting the conversion of lead sulphate to lead carbonate are solid–liquid ratio and reaction period. The optimum conversion conditions for process are found to be solid–liquid ratio of 0.05 g/mL, reaction period of 600 s, reaction temperature of 50 °C and Na₂CO₃ concentration of 2 M. Under optimal conditions, the experimental results put out that the conversion of lead sulphate at the 95% confidence level can be 97%, approximately.