Clickstream Big Data and “Delivery before Order Making” Mode for Online Retailers

Our research is inspired by a leading online retailer using clickstream big data to estimate customer demand and then ship items to customers or hubs near customers by a mode of “delivery before order making” (DBOM) mode. Using clickstream data to obtain advance demand information in order quantities, we integrate the forecasting with a singleitem uncapacitated dynamic lot sizing problem in a rolling-horizon environment. Using the simulated clickstream data, we evaluate the performance of DBOM mode

Optimization Method Based On Optimal Control

In this paper, we focus on a method based on optimal control to address the optimization problem. The objective is to find the optimal solution that minimizes the objective function. We transform the optimization problem into optimal control by designing an appropriate cost function. Using Pontryagin's Maximum Principle and the associated forward-backward difference equations (FBDEs), we derive the iterative update gain for the optimization. The steady system state can be considered as the solution to the optimization problem. Finally, we discuss the compelling characteristics of our method and further demonstrate its high precision, low oscillation, and applicability for finding different local minima of non-convex functions through several simulation examples

Designing public storage warehouses with high demand for revenue maximisation

International audienceThe design of public storage warehouses needs to fit market segments to increase the average revenue in an environment of high demand. This paper presents a revenue model integrated with queuing and price-demand theories to solve the design and pricing problem for public storage warehouses. We consider two demand cases in the model, which are exponential demand and piecewise linear demand. We also develop a solution based on dynamic programming techniques to solve the problem. Using data from a warehouse, we conduct numerical experiments. Results show that our approach can improve the expected revenue of public storage warehouses with high demand by 16.6% on average. We further conduct sensitivity analysis on price, and investigate the relation between revenue and price

Supply chain choice with financial constraints on the internet : Drop shipping vs. traditional channel

International audienceWhile some existing literature on e-commerce supply chains neglects financial constraints, this study analyzes channel choice on the internet between drop shipping and traditional channel in a supply chain including a wholesaler W and multiple financially constrained online retailers. Drop shipping is a new order fulfillment practice on the internet, wherein retailers focus on customer acquisition while forwarding orders to wholesalers. A traditional channel is another mode of operation that is widely used on the internet, where retailers own and handle inventory, while wholesalers extend credit conditioned on retailers’ financial status. To understand the impact of a retailer’s financial constraints on her supply chain structure on the internet, we formulate profit-maximizing inventory models for both wholesaler W and retailer R. By analyzing and comparing their expected payoffs under different channels, we find that the supply chain structure on the internet first depends on the critical fractile in a newsvendor setting, and subsequently it depends on R’s preference and capital level if the critical fractile of R is much larger than that of W. Furthermore, we discuss the choice of channel on the internet under different trade credit policies and find that W always provides two channel options conditionally under partial trade credit but may offer only one supply chain structure under full trade credit. Finally, we provide management insights by identifying the decision zones for different supply chain structures under full or partial trade credit on the internet.<br/

Study on a Transparent Similar Rock-Anchoring Structure under Impact Tests and Numerical Simulation Tests

Interface slip is one of the main failure forms of an anchor structure, but the debonding slip process of rockbolt cannot be directly observed under impact load, so it is important to study the failure mechanism of the interface debonding of an anchor structure. For this purpose, a kind of transparent similar rock-anchoring structure and a new rockbolt impact load test system were developed. The debonding process of the anchor structure was carried out based on the system and Particle Flow Code (PFC) simulation test. The main conclusions are as follows: Axial force of rockbolt decreases progressively from the load end to the other end, but the shear stress of the interfaces increases at the early stage and then decreases. The majority of shear stress is at I interface compared to shear stress at II interface. The crack in the transparent sample occurs first in the middle of the sample, then extends to the local position of the two interfaces and finally penetrates all cracks, and the debonding failure mode is dual-interface mixed. According to laboratory tests and PFC simulation tests, the crack growth process can be divided into three stages. The results of the PFC simulation tests are similar to those of the laboratory impact tests of rockbolt

Assignment rules in robotic mobile fulfilment systems for online retailers

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Optimal decisions in reducing loss rate of returnable transport items

International audienceReturnable transport items (RTI) have been commonly used due to their advantages in reducing packaging waste and improving supply chain sustainability. However, RTI loss will result in a mismatch between the products flow and the RTI supply, which will affect operational continuity. This paper studies a RTI supply chain consisting of a single manufacturer and a single retailer, assuming that the retailer can reduce RTI loss by investing in staff training. We first develop an inventory model to minimize the total cost of the system. Then we analyze the optimal decision of the closed-loop supply chain of RTI. We compare the case where the retailer invests in reducing RTI loss and the case where the retailer does not. The results show that the supply chain will be more efficient if the retailer invests in reducing RTI loss, and the total cost of the system will be reduced. However, the retailer will invest only when its cost decreases. Thereby, we consider side payments as an available incentive to stimulate the retailer to invest. Moreover, we build an asymmetric Nash bargaining model considering investment cost sharing to coordinate the RTI supply chain. We compare the total optimal cost of the manufacturer and the retailer. The results show that the system can be coordinated, and the optimal total costs of both the manufacturer and the retailer are reduced.<br/

Emergency Relief Routing Models for Injured Victims Considering Equity and Priority.

International audienceIn humanitarian aid, emergency relief routing optimization needs to consider equity and priority issues. Different from the general path selection optimization, this paper builds two models differentiated by considerations on the identical and diverse injured degrees, where the relative deprivation cost is proposed as one of the decision-making objectives to emphasize equity, and the in-transit tolerable suffering duration is employed as a type of time window constraint to highlight rescue priority. After proving the NP-hardness of our models, we design a meta-heuristic algorithm based on the ant colony optimization to accelerate the convergence speed, which is more efficient than the commonly-used genetic algorithm. Taking 2017 Houston Flood as a case, we find results by performing the experimental comparison and sensitivity analysis. First, our models have advantages in the fairness of human sufferings mitigation. Second, the role of the in-transit tolerable suffering time window cannot be ignored in humanitarian relief solutions. Various measures are encouraged to extend this type of time window for achieving better emergency relief. Finally, our proposed hybrid transportation strategy aiming at diverse injured degrees stably outperforms the separated strategy, both in operational cost control and psychological sufferings alleviation, especially when relief supplies are limited.<br/

Modeling parallel movement of lifts and vehicles in tier-captive vehicle-based warehousing systems

International audienceThis paper models and analyzes tier-captive autonomous vehicle storage and retrieval systems. While previous models assume sequential commissioning of the lift and vehicles, we propose a parallel processing policy for the system, under which an arrival transaction can request the lift and the vehicle simultaneously. To investigate the performance of this policy, we formulate a fork-join queueing network in which an arrival transaction will be split into a horizontal movement task served by the vehicle and a vertical movement task served by the lift. We develop an approximation method based on decomposition of the fork-join queueing network to estimate the system performance. We build simulation models to validate the effectiveness of analytical models. The results show that the fork-join queueing network is accurate in estimating the system performance under the parallel processing policy. Numerical experiments and a real case are carried out to compare the system response time of retrieval transactions under parallel and sequential processing policies. The results show that, in systems with less than 10 tiers, the parallel processing policy outperforms the sequential processing policy by at least 5.51%. The advantage of parallel processing policy is decreasing with the rack height and the aisle length. In systems with more than 10 tiers and a length to height ratio larger than 7, we can find a critical retrieval transaction arrival rate, below which the parallel processing policy outperforms the sequential processing policy.<br/