Scheduling distributed flowshops with flexible assembly and set-up time to minimise makespan

The scheduling problems under distributed production or flexible assembly settings have achieved increasing attention in recent years. This paper considers scheduling the integration of these two environments and proposes an original distributed flowshop scheduling problem with flexible assembly and set-up time. Distributed production stage is deployed several homogeneous flowshop factories that process the jobs to be assembled into final products in the flexible assembly stage. The objective is to find a schedule, including a production subschedule for jobs and an assembly subschedule for products, to minimise the makespan. Such a scheduling problem involves four successive decisions: assigning jobs to production factories, sequencing jobs at every factory, designating an assembly machine for each product and sequencing products on each assembly machine. The computational model is first established, and then a constructive heuristic (TPHS) and two hybrid metaheuristics (HVNS and HPSO) are proposed. Numerical experiments have been carried out and results validate the algorithmic feasibility and effectiveness. TPHS can obtain reasonable solutions in a shorter time, while metaheuristics can report better solutions using more yet acceptable time. HPSO is statistically comparable yet less robust compared with HVNS for small-scale instances. For the large-scale case, HPSO outperforms HVNS on both effectiveness and robustness.     

高质量浓度曲拉通X-100对煤泥浮选的抑制效应及机理

表面活性剂在煤泥浮选领域中应用广泛,且表面活性剂常被用于煤泥浮选促进剂,本文从另一个方面探究了表面活性剂在过量的情况下对煤泥浮选的抑制效应及其机理。以低灰煤粒和表面活性剂曲拉通X-100为研究对象,采用X射线光电子能谱(XPS)表征曲拉通X-100在煤表面的吸附状态,静态接触角测定仪测定曲拉通X-100对煤表面疏水性的影响,并探究了不同质量浓度曲拉通X-100液滴在煤粒表面的润湿与铺展情况,采用诱导时间测量仪分析不同质量浓度曲拉通X-100水溶液中的气泡与煤粒的黏附情况,最后通过紫外分光光度计定量表征浮选槽中残留曲拉通X-100质量浓度与不同浮选时间下浮选结果的对应关系。结果表明:高质量浓度曲拉通X-100会抑制煤粒上浮,随着浮选试验的进行,曲拉通X-100质量浓度逐渐降低,低质量浓度曲拉通X-100会促进煤粒被上浮气泡黏附而浮出;高质量浓度曲拉通X-100能够在煤粒表面发生有效吸附,该吸附属于物理吸附,且在一定程度上提高了煤表面的疏水性;高质量浓度曲拉通X-100水溶液更容易润湿煤表面,从而减缓了气泡-煤粒黏附过程中的液膜薄化与破裂速率;在高质量浓度曲拉通X-100水溶液中,气泡表面因罩盖有曲拉通X-100分子,导致气泡表面发生改性,难以与煤粒发生有效黏附。高质量浓度曲拉通X-100主要通过对气泡改性,以及减缓气泡与煤粒碰撞-黏附过程中的液膜薄化-破裂速率来抑制煤粒的浮选。     

On the feasibility of on-farm biogas-to-electricity conversion: To what extent is solid oxide fuel cells durability a threat to break even the initial investment?

Despite their promising features, adverse economic feasibility still hamper SOFCs wide implementation and this effect is emphasized as long as the system size is reduced. According to previous investigations, the biogas pre-treatment section represents a burden for the economic viability. Aiming at reducing the extent of installation costs in SOFC-based configurations, biogas partial upgrading through CO₂ gas-separation membranes is put forth as innovative solution against reforming. This innovative system concept is expected to make SOFCs more cost-effective, yet resulting feeding gas might cause a quicker SOFC performance decay. Besides solving this trade-off, the economic viability results strongly sensitive to subsidiary electricity prices in force according to the regulatory framework.This paper presents a comparative economic assessment regarding biogas-to-electricity conversion via Solid Oxide fuel cells (SOFCs) and mature technologies as internal combustion engines (ICEs). Results highlighted that, the innovative SOFC system is far more viable than reforming-based one, exhibiting a reasonable payback time, with an adequate subsidized electricity sale price (4 and 5 years for small/medium and large-size plants respectively when subsidy is 0.28 €/kWh), up to 1%_1000h degradation rate. On the other hand, whilst considering a SOFC degradation rate of 0.03%_1000h, the reforming-based system appears feasible only on large-size plants, yet recovering the initial capital expenditure in 9 years. Moreover, once the break-even point is reached, the gain in the net revenue produced by the innovative system is amplified in the event of small-size installation. This allows the possibility to undertake the risk of higher degradation rates (up to 2%_1000h) without jeopardizing the economic profitability. Therefore, in the present regulatory framework and under current capital costs projections, the innovative SOFC system appears as much profitable as ICE mature technology. Such effort in the design of the fuel pre-treatment unit can lever SOFC broad spreading into the market of small biogas producers.     

基于广义二次互相关的低信噪比信号时延估计

针对时延估计精度受噪声影响,导致时延估计不准确的问题,在现有广义二次相关算法的基础上,提出了一种改进的广义二次相关算法,通过将二次相关函数先做指数运算,降低噪声干扰,再将傅里叶逆变换得到的相关函数做高次方运算,达到锐化峰值提高时延正确率的目的。仿真结果表明,信噪比(SNR)在0~10 dB时,改进算法的均方根误差明显优于广义二次相关算法,正确率相比于广义二次相关算法也显著提高,且在更低SNR的情况下仍然具有一定优势。     

人工湿地-微生物电解池耦合系统的脱氮特性

实验构建了人工湿地-微生物电解池耦合系统（CW-MEC），并考察了CW-MEC在阴极有无曝气及不同水力停留时间（HRT）的条件下对生活污水的处理效果。实验结果显示，降低HRT会让CW-MEC阴极、阳极的COD去除率由91.11%±7.76%、86.58%±9.54%降低为77.81%±14.84%、81.44%±11.11%，氨氮去除率由58.54%±5.80%、58.22%±5.03%降低为48.04%±12.94%、48.27%±13.40%；阴极增加曝气会让CW-MEC阴极、阳极的COD去除率分别提高到89.51%±3.92%、82.40%±1.63%，阴极氨氮去除率提高到71.51%±16.44%，而阳极氨氮去除率不受影响；增加阴极曝气条件后，系统阴、阳极开始有硝酸盐氮积累，而CW-MEC阴极的硝酸盐氮含量明显低于对照组（CW-MFC）；通过电化学性能分析，相对于CW-MFC系统，CW-MEC具有更低的内阻；通过微生物多样性分析，CW-MEC系统具有更丰富的微生物多样性。     

超深溜井爆破一次成井技术实践

为解决溜井掘进效率低、安全性差等问题，以柿竹园多金属矿掘进出矿溜井为例，提出了爆破一次成井技术，根据矿山具体爆破条件，设计了布孔参数、装药结构和起爆顺序等。实践表明，爆破一次成井技术施工天井效果良好，溜井贯穿上下2个分段，与设计相符，相较于普通法施工天井，节约成本30.7%，节约时间58.3%，经济效益显著，施工周期短，且安全性好，值得在其他类似矿山推广应用。     

基于词法特征的恶意域名快速检测算法

针对互联网中恶意域名攻击事件频发，现有域名检测方法实时性不强的问题，提出一种基于词法特征的恶意域名快速检测算法。该算法根据恶意域名的特点，首先将所有待测域名按照长度进行正则化处理后赋予权值；然后利用聚类算法将待测域名划分成多个小组，并利用改进的堆排序算法按照组内权值总和计算各域名小组优先级，根据优先级降序依次计算各域名小组中每一域名与黑名单上域名之间的编辑距离；最后依据编辑距离值快速判定恶意域名。算法运行结果表明，基于词法特征的恶意域名快速检测算法与单一使用域名语义和单一使用域名词法的恶意域名检测算法相比，准确率分别提高1.7%与2.5%，检测速率分别提高13.9%与6.8%，具有更高的准确率和实时性。     

Distributed Control Strategy with Smith's Predictor in a Pilot-Scale Diabatic Distillation Unit

Intrinsic characteristics of distillation such as dead time and high nonlinearities do not allow the complete elimination of transient times when any external disturbance or set-point change occurs. Thus, aiming at the use of easy-tuning systems, a distributed-action control in trays of a diabatic distillation unit with Smith's predictor was implemented in the Simulink environment to further reduce transient times and out-of-specification product. The distributed-action strategy with Smith's predictor led to a reduction of 33.3 min (33 %) in the transient time of the top temperature control loop and 66 % in out-of-specification product, when compared with the conventional strategy, and thus is shown to be an efficient approach to increasing the productivity of distillation plants.