Electrification of a city bus network—An optimization model for cost-effective placing of charging infrastructure and battery sizing of fast-charging electric bus systems

The deployment of battery-powered electric bus systems within the public transportation sector plays an important role in increasing energy efficiency and abating emissions. Rising attention is given to bus systems using fast charging technology. This concept requires a comprehensive infrastructure to equip bus routes with charging stations. The combination of charging infrastructure and bus batteries needs a reliable energy supply to maintain a stable bus operation even under demanding conditions. An efficient layout of the charging infrastructure and an appropriate dimensioning of battery capacity are crucial to minimize the total cost of ownership and to enable an energetically feasible bus operation. In this work, the central issue of jointly optimizing the charging infrastructure and battery capacity is described by a capacitated set covering problem. A mixed-integer linear optimization model is developed to determine the minimum number and location of required charging stations for a bus network as well as the adequate battery capacity for each bus line. The bus energy consumption for each route segment is determined based on individual route, bus type, traffic, and other information. Different scenarios are examined in order to assess the influence of charging power, climate, and changing operating conditions. The findings reveal significant differences in terms of required infrastructure. Moreover, the results highlight a trade-off between battery capacity and charging infrastructure under different operational and infrastructure conditions. This paper addresses upcoming challenges for transport authorities during the electrification process of the bus fleets and sharpens the focus on infrastructural issues related to the fast charging concept.     

转杯纱方巾织物浆纱工艺研究

针对转杯纱的特点和方巾产品的最终用途,选用合理的浆料配方和浆纱工艺对其地经纱和毛经纱分别进行了上浆,不仅满足了织造要求,且实现了方巾产品的手感柔软和良好的吸水性。     

Disaggregation and consolidation of imperfect quality shipments in an extended EPQ model

We consider a standard economic production quantity (EPQ) model. Due to manufacturing variability, a fraction P of the produced inventory will have imperfect quality, where P is a random variable with a known distribution. We consider a 100% inspection policy and further assume that the inspection rate is larger than that of production. Thus, all imperfect quality items will be detected by the end of the production cycle. For such an augmented EPQ model, we first derive the new optimal production quantity assuming that the imperfect quality items are salvaged once at the end of every production cycle. Then, we extend this base model to allow for disaggregating the shipments of imperfect quality items during a single production run. Finally, we consider aggregating (or consolidating) the shipments of imperfect items over multiple production runs. Under both scenarios we derive closed-form expressions for both the economic production quantity and the batching policy, and show that our desegregation/consolidation schemes can lead to significant cost savings over the base model.     

含电动汽车的光/储/燃充电站最优容量配置及经济性分析

针对城市居民区充电难状况,建立一种包含光伏电池、燃料电池和储能蓄电池的电动汽车充电站容量配置模型。以成本最小化和负荷方差最小化为目标,采用NSGA-Ⅱ(二代非支配排序遗传算法)对模型进行求解。对于求得的可行解,首先使用净现值法对部分解进行经济性评估,然后采取峰谷负荷差率进行进一步评估,经过两轮筛选得出最优解。仿真算例验证了模型及评估方法的可行性。     

烯基琥珀酸酐（ASA）用于中性造纸施胶剂施胶性能及应用趋势

烯基琥珀酸酐(ASA)应用于中性造纸施胶可改变我国传统的松香酸性施胶效果和性能,显著提高纸张的防水性、拉力强度,增加纸张的耐磨性和白度,可生产出能长期保存的高质量纸张,并可以保护造纸设备和环境。     

Dynamic lot sizing problem with continuous-time Markovian production cost

This paper develops a polynomial algorithm for obtaining dynamic economic lot sizes in a single product multiperiod production system with the objective of minimizing total production and inventory costs over T periods. It is assumed that production costs are linear, inventory costs are concave, setup costs are zero and backlogging is not permitted in all periods. Moreover, the unit production cost is a stochastic variable, which is evolved according to a continuous-time Markov process over the planning horizon. The model is formulated as a stochastic dynamic programming (DP) optimization with the state variable being unit production cost. Then, it is solved using the backward dynamic programming approach. To justify the application of the proposed model, two practical cases are presented.     

The importance of understanding the shape of diverse ethnic female consumers for developing jeans sizing systems

This study has been conducted to investigate the fit issues related to the current apparel pants and jeans sizing system for diverse consumers, identifying body shape differences among ethnic groups. A total of 1335 women in a certain size range (Misses figure type sizes 2–20) were selected in the study. A Misses figure type size category is commonly used for adult women of average proportion and height. First, the body dimension differences among ethnic groups were examined with a single factor analysis of variance. Second, the fit of pants and jeans for the diverse consumers within the same size category was examined with the current standard sizing system, ASTM D5585 for adult female Misses figure type sizes 2–20. Three cases were programmed within a database: When each consumer selects a size for a pair of jeans based on (1) waist size; (2) hip size; and (3) waist height (usually pants length). And last, the results were analysed with fit comparison plots. Current jean consumers are racially diversified in the US and globally as well. This study revealed that ethnic groups had different fit problems and significant body shape differences. Even within the same figure type size category, a variety of body dimensions existed in each ethnic group. According to the fit problem assessment in this study, consumers within the same body figure type size category could not find the right fit of the pants and jeans within the current sizing system. Half of the female consumers could not find a garment to fit based on waist height (pants length) because the current sizing systems overlooked the effect of diverse consumers. This study will be useful for standardizing organizations to modify current sizing systems for diverse ethnic consumer groups as a demographic factor so that apparel companies could provide better quality of fit for their consumers in the global and local market.     

Container fleet sizing and empty repositioning in liner shipping systems

This paper considers the joint container fleet sizing and empty container repositioning problem in multi-vessel, multi-port and multi-voyage shipping systems with dynamic, uncertain and imbalanced customer demands. The objective is to minimize the expected total costs including inventory-holding costs, lifting-on/lifting-off costs, transportation costs, repositioning costs, and lost-sale penalty costs. A simulation-based optimization tool is developed to optimize the container fleet size and the parameterized empty repositioning policy simultaneously. The optimization procedure is based on Genetic Algorithms and Evolutionary Strategy combined with an adjustment mechanism. Case studies are given to demonstrate the results.     

Three-stage airline fleet planning model

One of the main factors affecting airline success is bringing supply and demand as closely together as possible. In order to achieve this goal, an airline needs to adopt an appropriate methodological approach for the fleet planning process. Selection of an aircraft for operating a defined route network is a key element which has a direct impact on the increase of an airline's profitability and on the reduction of an airline's costs. The objective of this paper is to develop a robust model for fleet planning that deals with both fleet size and fleet composition problems for airlines operating on short haul and medium haul routes. The three-stage model for fleet planning involves approximate fleet composition, fleet sizing and aircraft type selection based on fuzzy logic, heuristic and analytic approaches, and multi-criteria decision making, respectively. This model is exemplified with a hypothetical airline based at Belgrade Airport.