The Triple‐A supply chain (Lee 2004) has become one of the most influential concepts for practitioners and researchers in supply chain management. It stipulates that supply chains should strive to ...improve along the dimensions of agility, adaptability, and alignment, as opposed to focusing exclusively on cost and efficiency improvements. While various strategies have since been adopted across different industries to foster the Triple‐A, the digitalization movement poses both new challenges and opportunities for developing Triple‐A supply chains. In this article, we shall discuss an emerging mode of supply chain innovation, known as the consumer‐to‐manufacturer (C2M) model, and how it enables new possibilities for achieving Triple‐A “digital” supply chains. C2M establishes digital links between end consumers and upstream manufacturers and product designers, and provides a variety of tactics to shorten the information flow process of the supply chain. Our discussion focuses on the implementation of C2M at JD.com, a leading online retailer in China.
Abstract
Predictable stereoselective formation of supramolecular assembly is generally believed to be an important but complicated process. Here, we show that point chirality of a ligand decisively ...influences its supramolecular assembly behavior. We designed three closely related chiral ligands with different point chiralities, and observe their self-assembly into europium (Eu) tetrametallic tetrahedral cages. One ligand exhibits a highly diastereoselective assembly into homochiral (either ΔΔΔΔ or ΛΛΛΛ) Eu tetrahedral cages whereas the two other ligands, with two different approaches of loosened point chirality, lead to a significant breakdown of the diastereoselectivity to generate a mixture of (ΔΔΔΔ and ΛΛΛΛ) isomers. The cages are highly emissive (luminescence quantum yields of 16(1) to 18(1)%) and exhibit impressive circularly polarized luminescence properties (|
g
lum
|: up to 0.16). With in-depth studies, we present an example that correlates the nonlinear enhancement of the chiroptical response to the nonlinearity dependence on point chirality.
Recent development of new technologies and data analytics has unleashed the so-called smart city (SC) movement, which has been transforming the ways that cities (and their services) operate. This ...movement is in line with the operations management (OM) community’s pursuit of innovative research questions, and part of our community has already started working on this exciting area of SC OM. In this article, we shall discuss (i) the potential contribution that OM can make to the SC movement, that is, how OM research may help inform discussion and decision making in the public and private sectors. In particular, the core principle of making cities
smarter
is in line with the OM literature. We then discuss (ii) how and why SC operations can be an interesting topic that possibly expands the scope and depth of OM theory, through drawing links to the existing and new streams of OM literature. Finally, we present (iii) a few promising research directions and examples, in domains such as energy, transportation (mobility), and retail.
In this paper, we develop distribution-free models that solve the appointment sequencing and scheduling problem by assuming only moments information of job durations. We show that our min-max ...appointment scheduling models, which minimize the worst-case expected waiting and overtime costs out of all probability distributions with the given marginal moments, can be exactly formulated as tractable conic programs. These formulations are obtained by exploiting hidden convexity of the problem. In the special case where only the first two marginal moments are given, the problem can be reformulated as a second-order cone program. Based on the structural properties of this formulation, under a mild condition, we derive the optimal time allowances in closed form and prove that it is optimal to sequence jobs in increasing order of job duration variance. We also prove similar results regarding the optimal time allowances and sequence for the case where only means and supports of job durations are known.
This paper was accepted by Dimitris Bertsimas, optimization
.
Electric vehicles (EVs) have been proposed as a key technology to help cut down the massive greenhouse gas emissions from the transportation sector. Unfortunately, because of the limited capacity of ...batteries, typical EVs can only travel for about 100 miles on a single charge and require hours to be recharged. The industry has proposed a novel solution centered around the use of "swapping stations," at which depleted batteries can be exchanged for recharged ones in the middle of long trips. The possible success of this solution hinges on the ability of the charging service provider to deploy a cost-effective infrastructure network, given only limited information regarding adoption rates. We develop robust optimization models that aid the planning process for deploying battery-swapping infrastructure. Using these models, we study the potential impacts of battery standardization and technology advancements on the optimal infrastructure deployment strategy.
This paper was accepted by Dimitris Bertsimas, optimization.
This review aimed to summarize the currently available premium evidence to determine the effect of virtual reality (VR) on executive function (EF) in older adults with mild cognitive impairment ...(MCI), and to detect what level of immersive VR would be the most beneficial.
Five electronic databases, namely, PubMed, Embase, PsycINFO, CINAHL, and Cochrane Library were searched. Our research team screened the studies and extracted data according to our inclusion criteria. The methodological quality of each study was rated using the PEDro scale. When three or more studies reported the same outcome, a meta-analysis was conducted using Review Manager 5.4.1.
Finally, 14 randomized controlled trials with a total of 518 participants were included. VR training had an overall positive effect on cognitive flexibility, global cognitive function, attention, and short-term memory compared to the control groups. Additionally, semi-immersive VR was more effective in improving cognitive flexibility compared to the other two types of VR. The application of non-immersive level of VR had a significant effect on global cognitive function, attention, short-term memory, and cognitive flexibility.
VR may be effective in improving EF in older adults with MCI. However, the level of immersive VR that would be the most beneficial on EF still needs to be investigated with a greater number of well-designed studies.
University brand (UniBrand) is a recent concept, and its theoretical modelling is still somewhat inadequate. This paper examines how perceived service quality affects UniBrand performance, UniBrand ...image and behavioural intention. Using an online student survey, the present study obtained 528 usable responses. The conceptual model was validated using structural equation modelling. The study makes an innovative theoretical contribution by establishing a relationship between experience-centric brand performance and brand image, and the antecedents and consequences of this link. In addition, student satisfaction and trust were demonstrated to mediate the relationship between perceived service quality, brand performance, brand image and behavioural intention in a higher education context. However, there were no moderating effects of gender or mode-of-study on the model, confirming that the model is invariant across these variables. Overall, this model suggests the importance of experience-centric service quality attributes and how they affect university branding strategies for sustained positive intentions.
AtHKT1 is a sodium (Na(+)) transporter that functions in mediating tolerance to salt stress. To investigate the membrane targeting of AtHKT1 and its expression at the translational level, antibodies ...were generated against peptides corresponding to the first pore of AtHKT1. Immunoelectron microscopy studies using anti-AtHKT1 antibodies demonstrate that AtHKT1 is targeted to the plasma membrane in xylem parenchyma cells in leaves. AtHKT1 expression in xylem parenchyma cells was also confirmed by AtHKT1 promoter-GUS reporter gene analyses. Interestingly, AtHKT1 disruption alleles caused large increases in the Na(+) content of the xylem sap and conversely reduced the Na(+) content of the phloem sap. The athkt1 mutant alleles had a smaller and inverse influence on the potassium (K(+)) content compared with the Na(+) content of the xylem, suggesting that K(+) transport may be indirectly affected. The expression of AtHKT1 was modulated not only by the concentrations of Na(+) and K(+) but also by the osmolality of non-ionic compounds. These findings show that AtHKT1 selectively unloads sodium directly from xylem vessels to xylem parenchyma cells. AtHKT1 mediates osmolality balance between xylem vessels and xylem parenchyma cells under saline conditions. Thus AtHKT1 reduces the sodium content in xylem vessels and leaves, thereby playing a central role in protecting plant leaves from salinity stress.
Transportation network vulnerability envelope (TNVE), constituted by the upper and lower bounds of network performance among all possible disruption scenarios, has recently been proposed as a ...systematic tool to characterize the impact of simultaneous disruptions of multiple links in a transportation network. Both pessimistic and optimistic cases and the possible range of disruption consequences can be revealed by the TNVE, which can be modeled as a unified optimization problem without the need to enumerate and evaluate all possible disruption scenarios. Specifically, the TNVE problem can be formulated as a binary integer bi-level program (BLP), in which the upper-level problem maximizes/minimizes the remaining network performance under a given number of disrupted links, and the lower-level problem adopts the shortest path problem to check the post-disruption connectivity of each origin–destination (O-D) pair while circumventing the cumbersome path enumeration or path set pre-generation. However, the binary integer BLP is computationally intractable, which hinders the applications of TNVE in practice. This study aims to develop an efficient method based on the random key genetic algorithm (RKGA) for determining the TNVE under simultaneous multi-link disruptions. The main features and benefits of the proposed method include: (a) it simultaneously solves the upper- and lower-bound problems at the same time while guaranteeing the feasibility of all solutions in the solution procedure; (b) it improves the computational efficiency to ensure the applicability to real transportation networks; and (c) it can provide a variety of alternative solutions in addition to the single optimal one, which facilitates the derivation of TNVE buffer and identification of sub-important links. These benefits make the proposed method efficient and effective for solving the TNVE problem. The applicability of the proposed method is demonstrated with small and medium-sized networks, as well as a large-scale real road network. Numerical experiments are conducted to illustrate the usage of TNVE for vulnerability analysis of transportation networks.
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