An integrated production-inventory system in a multi-stage multi-firm supply chain

We first generalize a number of integrated models with/without lot streaming and with/without complete backorders under the integer–multiplier coordination mechanism, and then individually derive the optimal solution to the three- and four-stage model, using algebraic methods of complete squares and perfect squares. We subsequently deduce optimal expressions for some well-known models. For our model, we check that the optimal solution, which is algebraically derived, is a global one. We present three numerical examples for illustrative purposes. We finally suggest some future research work involving extension or modification of the generalized model.     

A generalized algebraic model for optimizing inventory decisions in a multi-stage complex supply chain

In this paper, we deal with more generalized inventory coordination mechanism in an n-stage, multi-customer, non-serial supply chain, where we extend and generalize pervious works that use algebraic methods to optimize this coordinated supply chain. We establish the recursive expressions for this multi-variable optimization problem. These expressions are used for the derivation of the optimal replenishment policy and the development of the solution algorithm. Further, we describe a simple procedure that can help in sharing the coordination cost benefits to induce all stages to adopt the inventory coordination mechanism. We provide a numerical example for illustrative purposes.     

Supply chain coordination through rebate induced contracts

In this paper three different types of rebate induced contract namely direct-rebate and revenue sharing contract; downward direct rebate contract; direct-rebate and effort sharing contract are proposed for supply chain coordination perspective. Effectiveness and flexibility of proposed contracts under linear and iso-elastic demand are discussed analytically. It is shown that under certain conditions both manufacturer and retailer can gain more profit by means of appropriate coordination contracts. Several important implications are derived analytically to point out relationship among characteristically different contracts. Results are illustrated with numerical examples.     

A technical note on “Optimizing inventory decisions in a multi-stage multi-customer supply chain”

We first generalize Khouja [Khouja, M., 2003. Optimizing inventory decisions in a multi-stage multi-customer supply chain. Transportation Research Part E: Logistics and Transportation Review 39 (3), 193–208] integrated model considering the integer multipliers mechanism and next individually derive the optimal solution to the three- and four-stage model using the perfect squares method, which is a simple algebraic approach so that ordinary readers unfamiliar with differential calculus can understand the optimal solution procedure with ease. We subsequently deduce the optimal expressions for Khouja (2003) and Cárdenas-Barrón [Cárdenas-Barrón, L.E., 2007. Optimal inventory decisions in a multi-stage multi-customer supply chain: a note. Transportation Research Part E: Logistics and Transportation Review 43 (5), 647–654] model, and identify the associated errors in Khouja (2003). We present two numerical examples for illustrative purposes. We finally shed light on some future research by extending or modifying the generalized model.     

Prospects for shared electric velomobility: Profiling potential adopters at a multi-campus university

Electric velomobility (e-velomobility) encompasses human movement using electric-assisted bicycles (pedelecs, or e-bikes), and the associated practices, systems and technologies. It is emerging as an active mode in developed economies. Electric bicycle sharing (EBS) schemes can attain higher per-vehicle use time and provide more equitable access than personal ownership. University campuses are ideal testing beds for such systems as young and lower-income groups are present there. The goal of this study is to understand the segmentation of the market for a hypothetical electric bicycle sharing scheme located in a multi-campus university. A cross-sectional survey was conducted at a multi-campus university in South East Queensland, Australia. Motives, reasons, and intention of students and staff for potential future use of a potential campus-based EBS scheme were revealed. Three distinctive potential user groups with varied modal, socio-demographic, and psychological characteristics emerged in the clustering analysis, namely: “multimodal enthusiasts” (28%), “car-loving pragmatics” (46%), and “car-loving skeptics” (26%). We identify the key market segments and potential adopters' demographics (residential location, country of origin, income, and academic major). Our results indicate that respondents who are more multimodal, especially those cycling often and with shared mobility experiences, are more positive about using e-bike sharing. Largely mono-modal car users tend to be more negative toward the scheme. International students also tend to be more positive. The individual preferences and attitudes toward campus-based shared e-velomobility, as revealed in this paper, provide important insights for planners, policymakers and sharing operators seeking to launch or improve uptake of such schemes.     

多式联运数据交换区块链技术应用研究

针对多式联运数据交换中存在的数据中心化、作业协同效率不高等问题,对铁水联运、公铁联运过程中数据交换需求进行分析,阐述多式联运和区块链技术在数据共享、信任机制、安全机制和合约机制等方面的契合点,提出基于区块链的包括基础层、区块链核心层、应用服务层、应用接口和业务层的总体架构方案,设计基于联盟链的网络架构方式,模拟基于区块链技术的铁水联运运单流转过程,以实现共享数据的去中心化,提高多式联运作业的协同性和安全可靠性,促进多式联运"一单制"建设。     

Optimizing inventory decisions in a multi-stage multi-customer supply chain

Most supply chain models focus on two-stage chains in which vendors supply material to one customer. In this paper, we formulate a three-stage supply chain model where a firm can supply many customers. We deal with three inventory coordination mechanisms between chain members and solve a cost minimization model for each. We show that some of the coordination mechanisms can result in a significantly lower total cost than matching production and delivery along the chain. We provide some insights into when the added complexity of the second and third coordination mechanisms lead to significant cost reductions.     

Railway trip speeds and areal coverage. The emperor’s new clothes of effectivity?

Europe’s railways have experienced a general decline in the second half of the 20th century and a renaissance since the 1980s. Total network length has decreased fundamentally while high-speed rail (HSR) line construction has soared since then. Accordingly HSR has stipulated a lot of research, but only recently HSR’s impacts on settlement structure and transport regimes have been studied in depth. We embrace a passenger’s point of view and utilize a generalized overview model for illustrating the trade-offs between trip speeds of complete trip chains, access/egress legs and mainline trip lengths. In order to estimate input parameters, an overview of railway network and settlement structure of Austria is empirically derived. In four scenarios, we vary these input parameters to study the impact of timetable integration, speed upgrades on mainlines and access/egress modes on trip speed in the Austrian case. Our results show that travel speed advantages of mainline speed increases are quickly countervailed by access/egress improvements or timetable integration improvements. We conclude that finding harmonized optimum speeds, introducing clock-face timetable design and improving access/egress modes are promising strategies in comparison to unscrutinized further maximization of mainline travel speed levels at the expense of feeder/distributor lines quality.     

New regional aviation policy in India: Early indicators and lessons learnt

In this article, we study the new regional aviation policy of India along with data collected on the performance of the scheme since its introduction in 2016. The scheme has multiple objectives. First, it wants to increase footprints of civil aviation to unserved and underserved airports of India. Second, it intends to make flying more affordable. It comes out, the aviation market in the country has expanded due to the addition of new routes under the scheme but data indicates that there is a regional imbalance in the performance of the scheme. Moreover, there are still questions on the long term sustainability of many routes and finding a solution for neglect of some priority regions. We have identified economic and commercial challenges that need to be addressed for the program to achieve its goals. The insights gathered during the study can be generalized and policy makers and managers of remote area air-connectivity schemes of different countries should find them useful.     

Inequalities in the London bicycle sharing system revisited: impacts of extending the scheme to poorer areas but then doubling prices

Cycling confers transport, health and environmental benefits, and bicycle sharing systems are an increasingly popular means of promoting urban cycling. Following the launch of the London bicycle sharing system (LBSS) in 2010, women and residents of deprived areas were under-represented among initial users. This paper examines how the profile of users has changed across the scheme’s first 3 years, using total-population registration and usage data. We find that women still make fewer than 20% of all ‘registered-use’ LBSS trips, although evidence from elsewhere suggests that the introduction of ‘casual’ use has encouraged a higher overall female share of trips. The proportion of trips by registered users from ‘highly-deprived areas’ (in the top tenth nationally for income deprivation) rose from 6% to 12%. This was due not only to the 2012 LBSS extension to some of London’s poorest areas, but also to a steadily increasing share of trips by residents of highly-deprived areas in the original LBSS zone. Indirect evidence suggests, however, that the twofold increase in LBSS prices in January 2013 has disproportionately discouraged casual-use trips among residents of poorer areas. We conclude that residents in deprived areas can and do use bicycle sharing systems if these are built in their local areas, and may do so progressively more over time, but only if the schemes remain affordable relative to other modes.     

The demand for cycle sharing: Examining the links between weather conditions,air quality levels,and cycling demand for regular and casual users

This paper examines temporal variation in the demand for cycling to understand how environmental conditions may promote or hinder active travel. The role of environmental conditions is considered in terms of the prevailing weather as well as the concentration levelof local air pollutants. Using data derived from the London Bicycle Sharing Scheme, a set of autoregressive distributed lag models are specified to explore these relationships. The models distinguish casual cyclists from regular cyclists to allow the analysis to consider the demand profiles of these two market segments separately rather than jointly. The analysis makes use of an open science approach, with the data inspected, the models applied, and the results derived being made freely available to interested parties through an online repository.The results of the models indicate that the demand of casual cyclists is more strongly linked to concurrent weather condition as compared to the demand of regular cyclists, though regular cyclists seem to be more inclined to delay trips to avoid inclement weather. The associations between cycling demand and air quality levels is mixed, with high concentrations of ozone linked with lower levels of demand from regular cyclists while high concentrations of particulate matter 10 are positively related to both regular and casual cycling demand. The findings of this paper could provide benefits to bicycle sharing system managers such as in planning the schedule of maintenance work as well as highlighting the need to inform cyclists about the actions they can take to reduce their exposure to local air pollutants.     

Service charge and capacity selection of an inland river port with location-dependent shipping cost and service congestion

The inland waterway transportation has attracted a lot of attention worldwide in the last fifteen years. This paper studies the location, service charge and capacity decision of an inland river port to maximize its revenue or profit. The cargo shippers are assumed to be uniformly distributed along the inland river and can be shipped to the junction port via pure road transportation service or transshipment service with the inland river port. The natural heterogeneity of the river’ navigational condition is modeled by a location-dependent waterway transportation cost and the service congestion on the port is captured by the M/M/1 queueing model. We analytically investigate the properties of the optimal solutions for various decision problems associated with the inland river port. The effects of the natural heterogeneity and port service congestion of those optimal solutions are investigated. Those theoretical results are carefully examined in the case study of the Yangtze River.     

The profit-maximization model for a multi-item distribution channel

This study focused on an area of emerging research: managing a multi-product and multi-echelon supply chain which produces and sells deteriorating goods in the marketplace. We formulated four profit-maximization models by considering the effects of channel coordination and a joint replenishment program on the supply-side cost control, taking into account the effect of the pricing scheme on demand and revenue increments. In addition, a profit-sharing mechanism based on channel rebates is proposed, which leads to Pareto improvements among the channel participants.     

The role of a non-profit organisation-run public bicycle-sharing programme: the case of Kitakyushu City,Japan

Public bicycle-sharing programmes (PBSPs) are experiencing enormous growth as an increasing number of cities worldwide are adopting the scheme. PBSPs are managed and operated by the private sector; by local community groups, including non-profit organisations (NPOs); and by local governments. In many Japanese cities where private bicycle sharing is high, the scale of PBSPs is relatively small, leading to challenges such as difficulty in securing funding and appointing operators. This paper proposes that NPOs may have the capacity to operate and effectively manage PBSPs in conjunction with other non-profit activities to promote community development. Using a case study approach and implementing a user perception survey, this study examines the experience of a small-scale, NPO-run PBSP in Kitakyushu City, Japan. Findings show that NPO management and operation added value to the PBSP. In addition, some users were interested in the PBSP beyond its role as a means of transport. These users tend to engage in local activities more frequently than other users. Finally, almost all of the users were satisfied with the bicycle-sharing service, regardless of their reasons for using the programme. The insights gained from these results may help improve small-scale PBSP implementation, policy, and planning, both in Japan and beyond.     

Designing optimal urban transport strategies: The role of individual policy instruments and the impact of financial constraints

This paper presents a methodology for the design of optimal transport strategies and the case study results of the methodology for the City of Edinburgh, using the two multi-modal transport/land-use models MARS and TPM. First, a range of policy instruments are optimised in turn and their relative impacts explored. Second, optimisations with and without financial constraints are performed and compared. Although both models produce similar optimal policies, the relative contribution of the instruments differs between models as does the impact on outcome indicators. It is also shown that by careful design it is possible to identify a strategy which costs no more than the do-minimum but which can generate substantial additional benefits. The optimisation methodology is found to be robust, and is able to be used with different transport models, and with and without financial constraints.     

How to promote sustainable public bike system from a psychological perspective?

The public bike system (PBS) has been actively promoted worldwide for the last decade. This study tried to find out policy strategies for sustainable PBS implementation targeting on the city that is under consideration of introducing bike sharing scheme. For this, the authors considered some psychological factors that may make impacts on PBS user's attitudes and hypothesized especially that individual environmental concern refers to an attitude toward environmental issues, influence an increase of their perceived value of PBS. The Norm Activation Model (NAM) is used to measure the public's environmental concern incorporating norm activation. In addition, willingness to pay (WTP) method is adopted to investigate the value of PBS individuals. Structural equation modeling (SEM) revealed that environmental concern influenced people's perception of the value of PBS. Furthermore, the positive correlation between environmental concern and awareness of consequences on cycling is observed. The study verifies how people perceive the value of a bike sharing system and how often people using a bicycle are dependent on their environmental concern. In conclusion, authors discuss how PBS could be promoted sustainably by suggesting policy strategies to enhance the perceived value of PBS and to increase bicycle use.     

铁路客运站配套停车场泊位数量计算模型

铁路客运站配套停车场主要用于停靠接、送旅客的非营运车辆和出租车与其他社会车辆。在考虑接旅客车辆在停车场停留时间、旅客列车到达时刻、乘坐接旅客车辆人数等因素的基础上,构建接旅客车辆所需泊位数计算模型,采用系数法构建送旅客车辆和其他社会车辆所需泊位数计算模型,形成停车场泊位数量计算模型。以计算石家庄客运站停车场所需泊位数量为例,通过模型应用验证,分析模型的有效性。     

An examination of the factors that impact upon multiple vehicle ownership: The case of Dublin, Ireland

This paper examines the characteristics of households with multiple car ownership in Dublin, Ireland. Data from the 2006 Census of Ireland are analysed to ascertain the characteristics of these households. The analysis of multiple car ownership presented herein examines individual specific, transport availability, and household characteristics to provide an indication of the individuals most likely to have access to more than one vehicle. Understanding the characteristics of households with more than one car is important for many reasons, such as how policies for emissions reductions or pricing regimes might affect households. Ireland, like many countries, has recently launched a number of electric vehicle and car sharing schemes. Traditionally these schemes have been aimed at reducing multiple car ownership, therefore it is important to develop an understanding of the households that would most likely give up an extra car and use a car sharing scheme or an electric vehicle. Also from a sustainability point of view, greater levels of car ownership can result in unsustainable transport patterns.This paper examines the Census data using a multinomial logit regression model to determine the relationships between multiple car ownership levels and several household characteristics. The findings of the paper demonstrate that occupation, public transport availability and residential density all have an impact upon the decision to own more than one vehicle.     

Understanding the usage of dockless bike sharing in Singapore

A new generation of bike-sharing services without docking stations is currently revolutionizing the traditional bike-sharing market as it dramatically expands around the world. This study aims at understanding the usage of new dockless bike-sharing services through the lens of Singapore's prevalent service. We collected the GPS data of all dockless bikes from one of the largest bike sharing operators in Singapore for nine consecutive days, for a total of over 14 million records. We adopted spatial autoregressive models to analyze the spatiotemporal patterns of bike usage during the study period. The models explored the impact of bike fleet size, surrounding built environment, access to public transportation, bicycle infrastructure, and weather conditions on the usage of dockless bikes. Larger bike fleet is associated with higher usage but with diminishing marginal impact. In addition, high land use mixtures, easy access to public transportation, more supportive cycling facilities, and free-ride promotions positively impact the usage of dockless bikes. The negative influence of rainfall and high temperatures on bike utilization is also exhibited. The study also offered some guidance to urban planners, policy makers, and transportation practitioners who wish to promote bike-sharing service while ensuring its sustainability.