Scheduling Check-in Staff with Hierarchical Skills and Weekly Rotation Shifts

The paper aims to schedule check-in staff with hierarchical skills as well as day and night shifts in weekly rotation.That shift ensures staff work at day in a week and at night for the next week.The existing approaches do not deal with the shift constraint.To address this,the proposed algorithm firstly guarantees the day and night shifts by designing a data copy tactic,and then introduces two algorithms to generate staff assignment in a polynomial time.The first algorithm is to yield an initial solution efficiently,whereas the second incrementally updates that solution to cut off working hours.The key idea of the two algorithms is to utilize a block Gibbs sampling with replacement to simultaneously exchange multiple staff assignment.Experimental results indicate that the proposed algorithm reduces at least 15.6 total working hours than the baselines.

Development of a Model for International Traveler’s Check-In Process Using Arena Software Tool

The increasing demand for airline services amidst limited resources results in passenger dissatisfaction and dwindling revenue for airports and airlines. The dynamics of service demand and resource supply results in check-in issues for the stakeholders in the commercial aviation industry. This has the effect of impacting negatively on service performance, cost of operations, customer satisfaction, and overall throughput. Hence, this paper modelled the travelers’ check-in process at the “D Wing” of the Departure Section of Murtala Muhammed International Airport (MMIA), Ikeja, using Arena Software Tool. The work was carried out by determining the parameters of the queues at designated service points in the check-in process. The primary data required to develop the model were acquired by direct observation of passenger flow and oral interview. Thus, the average check-in time was determined. Thereafter, a model of the international check-in system of the MMIA was developed using Arena software in combination with Microsoft Office tools. The data collected were therefore inputted into the model and simulated;the real result was compared with the simulation result of 133 completions and there was no significant difference. The result showed that the model is a representation of the real system under study. Further work will be tailored towards simulation (i.e. the model will be subjected to experimentation in order to have different scenario).

Simulation of a Model for International Traveler’s Check-In Process Using Arena Software Tool

With the current situation of insecurity in Nigeria and the worsening condition of Nigerian roads, there is increasing demand for air travel. This increasing demand for airline services amidst limited resources results in passenger dissatisfaction and reduction of revenue for airports and airlines. The dynamics of service demand and resource supply result in check-in issues for all the stakeholders in the commercial aviation industry. Hence, this research simulated the developed model for travelers’ check-in process at the “D Wing” of the Departure Section of Murtala Muhammed International Airport (MMIA), Ikeja, using Arena Software Tool. The simulation of the developed model was carried out by varying five different configurations of the servers with respect to the baggage weighing machines and passenger profiling devices to obtain the minimum average check-in time (ACT) for the process, with each configuration undergoing 133 completions of simulation runs. The result of the experimentation revealed that the 3 × 3 × 4 configuration of servers produced the smallest ACT of 18.25 minutes. This translates to a difference of about 58 minutes from the 76.16 minutes ACT of the real system;representing about 76% improvement in the check-in time of passengers. This study contributed to knowledge by revealing that the main choke points in the MMIA check-in system occur at the baggage weighing and passenger profiling areas as against the check-in counter sub-section as advanced by previous works. Furthermore, the research added value to knowledge by creating a balance between customer satisfaction and cost of operations thereby accommodating the interests of the passenger and the operator who are the two main stakeholders in the commercial aviation industry.

燃料理化特性与进气压力耦合对碳氢化合物排放的影响

通过一台改进的单缸轻型柴油机,研究3种进气压力(120、150和180 kPa)下燃料的滞燃期、十六烷值与进气压力的耦合对柴油机碳氢化合物(HC)排放的影响。使用纯柴油(B00)、B20燃料(按质量分数混合20%正丁醇和80%纯柴油的燃料)和B20+EHN(B20中添加0.7%质量分数的2-乙基己基硝酸盐)作为燃料进行实验研究。对B00和B20+EHN的碳氢排放进行比较,可知在进气氧浓度高于13%时,HC排放差值几乎不随进气氧浓度发生变化,不同压力的HC排放差异基本维持在0~1 g/(kw·h)范围内。对B20和B20+EHN的碳氢排放进行比较,可知在120、150和180 kPa的入口压力下,临界氧浓度分别为16%、15%和13%,缸内燃烧温度和燃烧持续期是影响两种燃料HC排放差异的主要因素,当进气氧浓度值低于各进气压力下的临界点时,不同的十六烷值引起的缸内燃烧温度差异加大了HC排放的差异,随着氧浓度的降低,缸内燃烧温度的影响程度增大。

Evaluation of Auto-Ignition Characteristics of Diesel Surrogate Fuels with the Same Derived Cetane Numbers at Changed Thermodynamic Environments

The ignition tendency of diesel fuels is highly sensitive to ambient conditions and fuel properties.In this study,the ignition characteristics of different diesel surrogate fuels with the same derived cetane numbers(DCN)were measured and compared in varied thermodynamic and oxidizing environments.The combustion pressures,heat release rates,ignition delays,and combustion delays of the test fuels were compared.The experimental results showed that the diesel surrogate fuels with the same DCNs exhibit similar ignition propensity at standard DCN test conditions.Further,for the test conditions of high cetane fuels,high ambient temperatures,and suficient oxygen concentrations,surrogate fuels with the same DCN have similar ignition behaviors,and using the DCN to evaluate fuel ignition tendency is appropriate.However,for the test conditions of low cetane fuels,low ambient temperatures,and reduced oxygen concentrations,different ignition behaviors are observed for the surrogate fuels with the same DCN,so at these conditions using DCN as the evaluation index for fuel ignition tendency may lead to higher uncertainty.

Descriptors-based machine-learning prediction of cetane number using quantitative structure–property relationship

The physicochemical properties of liquid alternative fuels are important but difficult to measure/predict, especially when complex surrogate fuels are concerned. In the present work, machine learning is used to develop quantitative structure–property relationship models. The fuel chemical structure is represented by molecular descriptors, allowing the linking of important features of the fuel composition and key properties of fuel utilization. Feature selection is employed to select the most relevant features that describe the chemical structure of the fuel and several machine learning algorithms are tested to construct interpretable models. The effectiveness of the methodology is demonstrated through the development of accurate and interpretable predictive models for cetane numbers, with a focus on understanding the link between molecular structure and fuel properties. In this context, matrix-based descriptors and descriptors related to the number of atoms in the molecule are directly linked with the cetane number of hydrocarbons. Furthermore, the results showed that molecular connectivity indices play a role in the cetane number for aromatic molecules. Also, the methodology is extended to predict the cetane number of ester and ether molecules, leveraging the design of alternative fuels towards fully sustainable fuel utilization.

加氢裂化装置加工渣油加氢柴油的工业试验

为实现渣油加氢柴油的高附加值利用,发挥加氢裂化装置在压减柴油产量方面的作用,开展了加氢裂化装置加工渣油加氢柴油的工业试验。加氢裂化装置负荷率为56%,掺炼21.4%的渣油加氢柴油后,部分渣油加氢柴油可以转化为非柴油组分,表观转化率为48.34%;加氢裂化柴油产品的硫、氮质量分数未受明显的影响,分别为1.3μg/g和低于0.3μg/g,相对于柴油加氢改质装置的柴油产品性质略有改善;加氢裂化柴油产品十六烷值为62.7,提高了17左右;柴油总产量降低14.09 t/h。采用加氢裂化装置加工渣油加氢柴油,优化了渣油加氢柴油加工路线,有效压减柴油组分,提高了柴油产品质量,为渣油加氢柴油的高附加值利用提供工业案例。

焦化汽柴油加氢装置掺炼重芳烃油的工业实践

某石化企业生产的催化裂化柴油(LCO)、C_(10)+重芳烃(HAB)产量大,性质差。为解决重芳烃油加工难问题,将部分LCO和HAB改至焦化汽柴油加氢装置进行加工,并开展了不同比例下掺炼重芳烃油工业试验,对比分析不同工况下原料性质、主要操作参数、产品性质、物料平衡等方面数据的变化。结果表明,在入口氢分压7.0 MPa、入口氢油体积比530~580条件下,掺炼约8%HAB后,可以得到硫质量分数7.3μg g、十六烷值49.2、多环芳烃质量分数6%的优质柴油调合组分。在低压、低氢油比条件下,较低反应温度即可使得芳烃饱和反应达到平衡,并可根据平衡转化率调整重芳烃掺入量。

质量平衡法测定正十六烷纯度

质量平衡法是基于被测物质质量分数总和为100%的前提下(全部杂质未知),通过气相色谱面积归一法计算正十六烷的有机纯度,卡尔·费休库伦法测定水分含量,色谱法测定挥发组分的含量,ICP-MS测定不挥发组分的含量。扣除测得杂质后,即得正十六烷的纯度。该方法为纯度定值的基准方法、广泛应用于正十六烷等有机物的纯度定值。

红外光谱法测定柴油中硝酸酯型十六烷值改进剂的含量

本文主要研究硝酸酯型十六烷值改进剂提升柴油的十六烷值效果,含不同浓度的硝酸酯型十六烷值改进剂的定性结果;利用红外光谱法原理研究一种柴油中该类型改进剂的定量方法,校正曲线的相关系数为0.9999,0.025%的精密度为7.7%,0.050%的精密度为9.9%,绝对偏差在0.000%~0.005%之间;比较不同方法测定硝酸酯型十六烷值改进剂,红外光谱法和分光光度计法。

GC-MS测定中间馏分油烃类分子组成研究与应用

基于操作简便、普及度高的气相色谱-四极杆质谱(GC-MS),利用模拟碳数切割与碳数校正,建立快速分析中间馏分油烃类碳数分布分子组成表征方法。该方法与测定中间馏分油烃类族组成标准分析方法NB/SH/T 0606—2019使用相同的仪器配置,在不增加硬件设备与分析时间的条件下,30 min即可同时得到烃类族组成、碳数分布以及正、异构链烷烃碳数分布等分子组成信息。利用该方法测定的碳数分布数据与配置软电离源的气相色谱-场电离飞行时间质谱(GC-FI TOFMS)测定数据基本一致。利用烃类分子组成计算出的碳、氢元素含量与标准分析方法NB/SH/T 0656—2017的测定结果相符。根据GC-MS测定的烃类分子组成数据,预测了45个柴油的十六烷值,预测值与实测值的偏差在±2.0之间。建立的表征方法解决了以往只有使用配置软电离源的中高分辨率质谱才能实现中间馏分油烃类分子组成表征的难题,在保障数据质量的前提下,降低了仪器成本,节省了实验时间,提高了分析效率。

基于FT-IR快速预测车用柴油十六烷值

车用柴油十六烷值是衡量柴油在压燃式发动机中发火性能的重要指标,也是车用柴油出厂时的关键质量指标之一。利用FTIR光谱和化学计量学方法建立车用柴油十六烷值的核偏最小二乘法定量分析模型,相关系数R为0.97,均偏差为0.05,标准差0.05,说明模型建立的方法较好。进一步对模型进行验证和评价,验证集的20个样品的十六烷值相关系数R为0.95,预测均方差(RMSEP)为0.44。说明模型的预测效果很好,能满足生产中车用柴油检测精度基本要求,所建的数学模型具有良好的预测能力,可以达到常规分析方法的精度要求。

CFR F-5十六烷值机校验方法研究

十六烷值机是用于测试柴油在压燃发动机着火时十六烷值的专业设备。本文详细介绍了其校验方法的重要性和方案设计,并通过大量校验实验验证可行性、有效性。实验证明:该方法可有效提高行业在柴油十六烷值检测领域的技术水平。

柴油十六烷值改进剂研究新进展

对国内外柴油十六烷值改进剂的研究进展进行了综合论述,主要有含氮化合物和含氧化合物两大类别,金属类十六烷值改进剂也初露端倪。同时,简述了十六烷值改进剂的感受性、复配现象,对十六烷值改进剂作用的一般机理进行了阐述。通过综述,对十六烷值改进剂的发展方向作出了合理预测。

有机硝酸酯类柴油十六烷值改进剂的研究

研制了一种成分为脂环族硝酸酯的柴油十六烷值改进剂，并测定出这种改进剂的一系列理化性质。分析了有机硝酸酯缩短柴油着火滞燃期的化学动力学机理。实机研究了这种改进剂对柴油十六烷值和燃烧特性的改善效果，以及对柴油机燃油消耗量和烟度的影响。研究结果表明，脂环族硝酸酯作为柴油十六烷值改进剂具有很高的使用价值。

植物油加氢制备高十六烷值柴油组分研究进展

介绍了植物油加氢制备柴油的主要化学反应、工艺方法以及该项技术的工业化状况,分析了植物油直接加氢、先加氢后异构、直接脱羧工艺以及植物油与矿物柴油掺炼工艺的特点,阐述了各工艺采用的催化剂类型、工艺条件以及产品属性。指出了该领域存在的问题和研究方向。

基于位置签到数据的城市分层地标提取

为了及时准确地获取用于智慧位置服务的城市层次性空间知识,该文提出了一种依据签到属性显著度的差异从位置签到数据中提取城市分层地标的方法.首先,针对传统基于调查问卷的公众认知度计算方法存在的不足,该文从位置签到数据中的签到次数、签到用户数和用户影响因子3个方面入手讨论POI显著度的影响因素,进而提出了一种基于签到数据的POI显著度计算模型;然后,利用Voronoi图对POI空间作用范围进行分割并结合邻域分析与合并算法逐层迭代,形成了基于签到POI显著度与Voronoi图的分层地标提取算法;最后,以北京市的位置签到数据为例,进行了POI显著度计算与分时分层地标提取,通过与现有实体、网络地图资料的比对,验证了算法的有效性,并进一步分析了分层、分时地标反映的空间现象和规律,为个性化智慧位置服务提供城市层次性空间知识.

MHUG技术生产满足欧Ⅴ排放标准柴油的研究

从柴油烃类组成和化学反应的角度对MHUG技术的基本原理进行阐述,同时针对不同企业的多个原料构成在中试装置上开展MHUG技术生产满足欧Ⅴ排放标准要求柴油的研究。结果表明,采用MHUG技术可以生产硫含量小于10μg/g、十六烷值为51以上的清洁柴油产品,且对各种原料构成均有良好的适应性。

劣质催化裂化柴油加氢改质技术的开发及工业应用

在中型试验装置上对劣质催化裂化柴油 ,在氢分压 6.4MPa条件下进行加氢改质 ,通过应用加氢精制催化剂RN 1和加氢裂化催化剂RT 5的加氢改质工艺可以生产质量收率在 90 %～95%的优质柴油馏分 ,其十六烷值较原料可提高 1 0～ 1 5.7个单位 ,副产品石脑油馏分油的芳烃潜含量在 70 %左右。该技术于 1 998年初在武汉石油化工厂 30 0kt/a加氢改质装置上实现了首次工业应用 ,工业结果与中型结果一致。

柴油加氢改质过程烃类反应与十六烷值的关系

在固定床中型加氢实验装置上,以石家庄炼化分公司催化裂化柴油为原料,在氢分压10.0MPa、体积空速1.14h-1、氢/油体积比1000、反应温度360℃的条件下,考察了加氢改质精制段各主要烃类的化学反应过程;在氢分压10.0MPa、体积空速2.68h-1、氢/油体积比1000、精制段反应温度360℃的条件下,考察了加氢改质的改质段不同反应温度下的化学反应过程。结果表明,精制段中,芳烃的加氢饱和反应对十六烷值的正向贡献约为18.46个单位,长侧链烃类断裂为短侧链烃类的反应对十六烷值的负向贡献约为1.06个单位,正负向的综合作用使得十六烷值提高17.40个单位;改质段中,芳烃加氢饱和反应和环状烃开环裂化反应对十六烷值的正向贡献为3.93～6.60个单位,长侧链烃类断裂为短侧链烃类的反应对十六烷值的负向贡献为0.33～1.19个单位,综合作用的结果使得改质产品柴油与精制油相比十六烷值提高3.60～5.50个单位。