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Electric vehicles (EVs) are now widely acknowledged as ideal means of transportation in future, in terms of energy conservation and environmental protection for urban governance. EV lease service is an effective measure to promote the use of EVs and has gained the support of many countries. In this article, a comprehensive pricing scheme is developed to optimize the annual operations profit for EV lease service based on mileage-based pricing (MBP), where the profit is defined as the revenue subtracted by the maintenance cost. Different from the traditional MBP for vehicle lease service, our model characterizes how the grade level of EVs affects the maintenance cost after each failure. Moreover, the lease service is modeled as a queuing system where each consumer has the probability choosing the MBP by comparing the service value and his expense. An enumerative algorithm is developed to find the optimal pricing as well as analyze the influence of parameters on the optimal profit. The algorithm is implemented in the pricing of an EV lease company in China. The results show that the optimal pricing will increase with service rate, consumer arrival rate, and the service value from lessor, but decrease with waiting cost of consumers. Differential pricing strategies are also proposed to resolve the conflict goals of lessors and consumers, which can further boost lessors’ profit and raise consumers’ satisfaction level. The results show that MBP with differential pricing strategies will increase profit between 2.3% and 69.8%, comparing with cases without differential pricing strategies.

PurposeServitization is a business transformation that increases service provision in manufacturers. This study aims to empirically examine how a manufacturer's global supply chain dependence and its power positions affect its servitization output.Design/methodology/approachThis study employs secondary longitudinal datasets and econometric specifications to test the relationship between global supply chain dependence and servitization. It further examines the moderating roles of the firm's market power and the degree of being principal customers and principal suppliers. Heterogeneity analyses are performed to verify the robustness of the results.FindingsThe findings indicate that fewer global suppliers and more global customers contribute to a higher level of servitization. The negative effect of global supplier dependence is mitigated when manufacturers have less market power and are the principal customers for most of their suppliers. The positive effect of global customer dependence is stronger when manufacturers have less market power and their customers are less dependent on the manufacturers.Research limitations/implicationsData mixing manufacturing and service inputs and data on public US manufacturers may restrict the generalizability of the findings. Nonetheless, the study urges future research to focus more on other countries/markets.Practical implicationsThis study encourages manufacturers who servitize their businesses to connect with more global customers and fewer global suppliers and manage powers among stakeholders. Other recommendations for policymakers and industry associations are also proposed.Originality/valueThis study is the first to explore the impacts of the global supply chain dependence on servitization. Multiple-level findings offer important implications for researchers and practitioners.

After a long period of water flooding development, oilfields will enter the production stage of "high water cut, high recovery degree, and low oil recovery rate". On the one hand, due to the displacement effect of the water injection, some oil layers already reached the water flooding limit. On the other hand, due to the effect of reservoir heterogeneity, dominant seepage channels, and imperfect injection-production well pattern, some oil layers are enriched with a large amount of remaining oil. Unbalanced production of reservoirs and difficulty in development and adjustment are common problems in mature oilfields. Mature multi-layer oilfields generally develop many sets of oil-bearing layers vertically. After a long water injection period, the water-flood law and the remaining oil distribution are complex, and the production of different well patterns or strata varies greatly. Through strata and well pattern reorganization, combined with the evaluation results of water flooding adjustment potential, some reservoir engineers and researchers established a stereoscopic development adjustment mode for enhanced oil recovery in mature multi-layer oilfields. This paper summarizes the main technologies of stereoscopic development adjustment mode for enhanced oil recovery in mature multi-layer oilfields. The main technologies of stereoscopic development adjustment mode include research on the remaining oil distribution, evaluation of water flooding adjustment potential, selection of tertiary oil recovery methods, reorganization of strata and well pattern, and optimization of timing from water flooding to tertiary oil recovery, etc. For strata with low water flooding adjustment potential, the tertiary oil recovery well pattern is reorganized and tertiary oil recovery is adopted to improve oil recovery. For strata with large water flooding adjustment potential, the water drive well pattern is reorganized and water flooding development is used to excavate the remaining oil. As for strata with general water flooding adjustment potential, the tertiary oil recovery well pattern is reorganized and water flooding development is used to excavate the remaining oil first, and then transfer to tertiary oil recovery at the proper time. The stereoscopic development adjustment mode is applied to test block K of Q reservoir which is a mature multi-layer oilfield. After stereoscopic development adjustment, the development effect of test block K meliorates. It is estimated that the EOR will be increased by more than 8% after stereoscopic development adjustment in test block K.

Foam flooding has been widely studied and implemented in recent years to alleviate reservoir heterogeneity and increase oil recovery. Previously, foam flooding was employed for conformance control and improving sweep efficiency, and little attention was paid to displacement efficiency. Thus, foam flooding usually had a poor ability to trip off oil film. Moreover, the effectiveness of many of the foam pilots lasted only a few months, and, in some cases, only a few weeks, which limited the long-term development of foam in field applications as the time to maximize effectiveness was too short. In this paper, a foam pilot selection, formulation design, and N2 foam pilot implementation are presented towards providing an effective method for transforming the development mode after water flooding in low-permeability reservoirs. Two well groups (two injection wells and 17 production wells) were screened as candidates for the N2 foam pilot. Laboratory investigations included bulk foam screening, imbibition recovery, and natural core flooding tests. One formulation of eight tested (No. 6) showed excellent foam properties as well as a strong ability to strip oil from sand, and natural core scale work under reservoir conditions resulted in a total recovery of 66.92%, with an incremental recovery of 25.25% by N2 foam after water flooding. The pilot was deployed using a new injection strategy of a surfactant alternating gas method in which surfactant was injected into water for 1 d at a normal injection rate followed by N2 injection for 1 d at a large injection rate. A positive response was observed after injection for approximately 1.5 months, daily oil production climbed sharply, and water cut also decreased after processing of 1% of pore volume with foam solution. Moreover, production was sustained for 18 months after foam injection, which resulted in approximately 4375 t of incremental oil. The foam pilot was successful in addressing the challenges associated with dominant channel and low displacement efficiency of water flooding in low permeability sand reservoirs.

When a fixed number of support vector machines (SVMs) are taken as the base learners, an attempt to diversify them should be encouraged to achieve a satisfactory ensemble. In this article, by means of a negative agreement learning (NAL) strategy, a new SVM-based ensemble framework is proposed to simultaneously enhance the diversity of SVMs in the ensemble and suppress the training error of the ensemble. The proposed ensemble framework is theoretically derived to have distinctive merits: 1) the ensemble and each of its individual SVM base learner are trained in a joint manner rather than in an independent manner and 2) the NAL strategy facilitates the formulation of the ensemble of SVMs as one single SVM; thus, abundant advances in the training of SVM can be conveniently applied to the proposed ensemble learning of SVMs and there is no need to design special optimization techniques for the involved ensemble learning. Extensive experimental studies demonstrate the effectiveness of the proposed ensemble framework of SVMs.

Graphene-based photodetectors have attracted significant attention for high-speed optical communication due to their large bandwidth, compact footprint, and compatibility with silicon-based photonics platform. Large-bandwidth silicon-based optical coherent receivers are crucial elements for large-capacity optical communication networks with advanced modulation formats. Here, we propose and experimentally demonstrate an integrated optical coherent receiver based on a 90-degree optical hybrid and graphene-on-plasmonic slot waveguide photodetectors, featuring a compact footprint and a large bandwidth far exceeding 67 GHz. Combined with the balanced detection, 90 Gbit/s binary phase-shift keying signal is received with a promoted signal-to-noise ratio. Moreover, receptions of 200 Gbit/s quadrature phase-shift keying and 240 Gbit/s 16 quadrature amplitude modulation signals on a single-polarization carrier are realized with a low additional power consumption below 14 fJ/bit. This graphene-based optical coherent receiver will promise potential applications in 400-Gigabit Ethernet and 800-Gigabit Ethernet technology, paving another route for future high-speed coherent optical communication networks., Graphene-based photodetectors have many advantages for applications. Here, the authors demonstrate a high-speed optical coherent receiver for optical communications based on graphene-on-plasmonic slot waveguide photodetectors.

Manufacturing servitization has become a major trend in industry that is implemented by so called integrated production and service systems (IPSSs) to offer not only products but also their associated services. In this study, we explore the capacity allocation policy for an IPSS that consists of a manufacturing facility and a service center. The IPSS serves two classes of customers, each demanding a specific product produced at the manufacturing facility and, subsequently, the associated service offered by the service center. We formulate this problem of resource allocation as a Markov decision process. Our analysis suggests that it is optimal to serve the customer with the larger cost saving rate and slower service rate, where the cost saving rate equals service rate times the sum of holding cost and waiting cost. Then we explore production control policies coupled with optimal service ones. We demonstrate that, with light service traffic, the system under the optimal production policy becomes similar to a make‐to‐stock system. Such a system can effectively hedge the system uncertainty. Therefore, the optimal production policy for the IPSS is also a hedging point policy. Under this policy, switching and idling curves split the state space into three regions: one without any production, the two others for production of two type products, respectively. We also discuss the optimal control policies of the two extensions of the IPSS (one with multiple types of product and customers, and the other with a single product and two classes of customers) and find that the characters of the optimal production and service policy still hold. Finally, we develop three heuristic integrated scheduling policies. Numerical experiments show that one is very effective.