| 1. |
- Amorim, Pedro, et al.
(författare)
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Customer Preferences for Delivery Service Attributes in Attended Home Delivery
- 2024
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Ingår i: Management science. - 0025-1909 .- 1526-5501.
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Tidskriftsartikel (refereegranskat)abstract
- Retailers face increasing competitive pressure to determine how best to deliver products purchased online to the end customer. Grocery retailers often require attended home delivery where the customer must be present to receive the delivery. For attended home delivery to function, the retailer and customer must agree on a delivery time slot that works for both parties. Using online data from a grocery retailer, we observe customer preferences for three delivery service attributes associated with each time slot: speed, precision, and timing. We define speed as the expected time between the placement of an order and its delivery, precision as the duration of the offered time slot, and timing as the availability of choices across times of the day and days of the week. We show that customers not only value speed as an attribute of delivery service but that precision and timing are also key drivers of the customer's time slot selection process. We also observe substantial customer heterogeneity in the willingness of customers to pay for time slots. Customers that differ in their loyalty to the retailer, basket value, basket size, and basket composition exhibit distinct differences in their willingness to pay. We show that retailers with the capability to tailor their time slot offerings to specific customer segments have the potential to generate approximately 9% more shipping revenue than those who cannot. Our findings inform practitioners seeking to design competitive fulfillment strategies and academics customer behavior in the attended home context.
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| 2. |
- Bharali, Ritukesh, 1991, et al.
(författare)
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A micromorphic phase-field model for brittle and quasi-brittle fracture
- 2024
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Ingår i: Computational Mechanics. - 1432-0924 .- 0178-7675. ; 73:3, s. 579-598
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Tidskriftsartikel (refereegranskat)abstract
- In this manuscript, a robust and variationally consistent technique is proposed for local treatment of the phase-field fracture irreversibility. This technique involves an extension of the phase-field fracture energy functional through a micromorphic approach. Consequently, the phase-field is transformed into a local variable, while a micromorphic variable regularizes the problem. The local nature of the phase-field variable enables an easier implementation of its irreversibility using a pointwise 'max' with system level precision. Unlike the popular history variable approach, which also enforces local fracture irreversibility, the micromorphic approach yields a variationally consistent framework. The efficacy of the micromorphic approach in phase-field fracture modelling is demonstrated in this work with numerical experiments on benchmark brittle and quasi-brittle fracture problems in linear elastic media. Furthermore, the extensibility of the micromorphic phase-field fracture model toward smultiphysics problems is demonstrated. To that end, a theoretical extension is carried out for modelling hydraulic fracture, and relevant numerical experiments exhibiting crack merging are presented. The source code as well as the data set accompanying this work would be made available on GitHub (https://github.com/ritukeshbharali/ falcon).
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| 3. |
- Jonsson, Simon, 1987-, et al.
(författare)
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Studying the rate-dependence of Essential Work of Fracture in press hardening steels
- 2024
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The automotive industry is currently in a paradigm shift transferring the fleet over from internal combustion vehicles to battery electric vehicles (BEV). This introduces new challenges when designing the Body-In-White (BIW) since it is essential to protect the heavy and energy-dense battery in a crash scenario. Press hardening steels (PHS) have emerged as an excellent choice when designing crash safety parts due to their high-strength and forming flexibility. It is however crucial to evaluate the crash performance of the selected materials before producing parts. Component testing is cumbersome, and it is difficult to separate material behaviour from other influences such as spot welds. Fracture toughness measured in the frame of fracture mechanics using the Essential Work of Fracture (EWF) has emerged as an interesting tool to rationalise crash performance of steel sheet designs. The EWF has previously been shown to increase, sometimes substantially, with increasing strain rate, but the cause of this is still largely unknown. For high strain rates, adiabatic heating can have a significant effect on the mechanical and fracture properties, especially for steel grades with metastable austenite. However, the rate dependence is still evident for press hardened martensitic steel grades. In this work, quasi-static and high-speed EWF experiments are performed on two PHS grades designed for anti-intrusion and energy absorption, respectively. The thermals are monitored using infrared thermography to study the adiabatic heating and thus the thermal environment in the FPZ during EWF at high-loading rates. The results are compared and discussed.
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| 4. |
- Ansin, Caroline, 1996, et al.
(författare)
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Fast simulation of 3D elastic response for wheel–rail contact loading using Proper Generalized Decomposition
- 2023
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Ingår i: Computer Methods in Applied Mechanics and Engineering. - 0045-7825. ; 417
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Tidskriftsartikel (refereegranskat)abstract
- To increase computational efficiency, we adopt Proper Generalized Decomposition (PGD) to solve a reduced-order problem of the displacement field for a three-dimensional rail head exposed to different contact scenarios. The three-dimensional solid rail head is modeled as a two-dimensional cross-section, with the coordinate along the rail being treated as a parameter in the PGD approximation. A novel feature is that this allows us to solve the full three-dimensional model with a nearly two-dimensional computational effort. Additionally, we incorporate the distributed contact load predicted from dynamic vehicle-track simulations as extra coordinates in the PGD formulation, using a semi-Hertzian contact model. The problem is formulated in two ways; one general ansatz which considers the treatment of numerous parameters, some of which exhibit a linear influence, and a linear ansatz where multiple PGD solutions are solved for. In particular, situations where certain parameters become invariant are handled. We assess the accuracy and efficiency of the proposed strategy through a series of verification examples. It is shown that the PGD solution converges towards the FE solution with reduced computational cost. Furthermore, solving for the PGD approximation based on load parameterization in an offline stage allows expedient handling of the wheel-rail contact problem online.
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| 5. |
- Baldauf, Christoph, 1990-
(författare)
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Empirical Essays on Retail Logistics and Customer Behavior
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Retail logistics is responsible for making products available to end customers. Traditionally, this was facilitated through a network of brick and mortar stores that customers visit to buy items. However, the advent of online and omnichannel retail started to challenge this established system. Modern-day customers increasingly buy a product not solely for its features but also for how, and how fast, the item is delivered and/or returned. Such customer behavior shows that retail logistics often is the decisive factor when searching for, purchasing, and using goods and services. Consequently, logistics performance has become increasingly important for marketing performance. This is in stark contrast to logistics (often) outdated characterization as a back-office operation focusing on cost-effectiveness and lead-time reductions. To overcome the prevailing cost focus, more knowledge is needed that is based on the incorporation of customer behavior into operations management models to demonstrate to retailers the elevated role of logistics in retail today. Therefore, the overall purpose of this dissertation is to contribute to a better understanding of the relevance of logistics in online and omnichannel retail, and its impact on customer behavior.This purpose is explored in four research articles that examine the relevance of logistics from various angles. Article I is a systematic literature review synthesizing empirical literature on the impact of logistics on customer purchase, repurchase, and return behavior in online and omnichannel retail. Article II analyzes how carrying a stock-keeping unit in inventory at the warehouse affects its sales in online retail. Article III investigates how an online retailer’s change in return policy to free returns increases purchases from customers, but also the volume of items being returned to the retailer. Finally, Article IV examines how a buy-online-return-to-store policy in omnichannel retail impacts store performance.The theoretical contributions to the literature are as follows. First, the dissertation illustrates the relevance of logistics in retail today by showing how logistics does not only impact the cost side of a business but also customer behavior and, hence, the demand side. Second, the research highlights the integrative approach that retailers need to adopt between the marketing and operations functions to operate successfully, as action taken by one business function increasingly impacts the other. Third, the dissertation accentuates the role of people in operations management research. It emphasizes how customer behavior is impacted by retail logistics, and thus adds to a better understanding of how people affect real-life operational processes.
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| 6. |
- Baldauf, Christoph, et al.
(författare)
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Where to Cut the Long Tail? The Value of Carrying Inventory in Online Retail
- 2023
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Ingår i: Management science. - 0025-1909 .- 1526-5501.
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Tidskriftsartikel (refereegranskat)abstract
- One advantage of online retail is that a large number of products can be displayed at low cost. However, online retailers must decide which of these products to carry in inventory (stock items), and which to order from suppliers when a customer places an order (non-stock items). In this paper, we empirically investigate how carrying a product in inventory affects its online sales. We use data from a European furniture and interior design retailer consisting of daily sales transactions and inventory data covering 18 months. We use a quasi-natural experiment—random transitions of products in and out of inventory at the retailer's central warehouse—to estimate the causal effect of carrying inventory on sales. Our results show a strong and statistically significant increase in sales, of on average 65%, associated with having the product available in stock. More interestingly, this effect differs between products and is moderated by the price of the product: Sales of more expensive products are less sensitive to the product being in stock. We use these results to draw insights on which types of items to carry in inventory.
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| 7. |
- Börjesson, Elias, 1992, et al.
(författare)
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Variationally consistent homogenisation of plates
- 2023
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Ingår i: Computer Methods in Applied Mechanics and Engineering. - 0045-7825. ; 413
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Tidskriftsartikel (refereegranskat)abstract
- Advanced fibre composite materials are often used for weight-efficient thin-walled designs, making a plate-based modelling approach suitable for their structural assessment. However, as the sub-structural geometrical features of these materials govern much of their behaviour, a multi-scale approach is necessary. A related challenge, however, is that the in-plane variation of these sub-structural features may be much larger than the total thickness of the material, whereby tailored homogenisation techniques for shell elements are needed. Existing frameworks for plate- and shell-based homogenisation are typically developed using second-order homogenisation in combination with the Hill–Mandel (macro-homogeneity) condition. However, it has been reported in the literature that this approach can lead to kinematic inconsistencies in the macro- to micro-scale transition. One inconsistency that is commonly reported, is the inability to correctly account for the macro-scale transverse shear behaviour on the sub-scale level. In this contribution, we show how the method of Variationally Consistent Homogenisation (VCH) can be used to develop a homogenisation framework for Reissner-Mindlin plate elements, which guarantees kinematically consistent prolongation and homogenisation operations. The homogenisation approach is demonstrated in four numerical examples, where it is shown that the method accurately homogenise the effective sectional plate stiffnesses of homogeneous and heterogeneous sub-structures.
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| 8. |
- Carlstedt, David, 1984, et al.
(författare)
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Variationally consistent modeling of a sensor-actuator based on shape-morphing from electro-chemical–mechanical interactions
- 2023
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Ingår i: Journal of the Mechanics and Physics of Solids. - 0022-5096. ; 179
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Tidskriftsartikel (refereegranskat)abstract
- This paper concerns the computational modeling of a class of carbon fiber composites, known as shape-morphing and strain-sensing composites. The actuating and sensing performance of such (smart) materials is achieved by the interplay between electrochemistry and mechanics, in particular the ability of carbon fibers to (de)intercalate Li-ions repeatedly. We focus on the actuation and sensing properties of a beam in conjunction with the appropriate “through-the-thickness” properties. Thus, the electro-chemo-mechanical analysis is essentially two-dimensional, and it is possible to rely heavily on the results in Carlstedt et al. (2020). More specifically, the cross-sectional design is composed of two electrodes, consisting of (partly) lithiated carbon fibers embedded in structural battery electrolyte (SBE), on either side of a separator. As a result, the modeling is hierarchical in the sense that (macroscale) beam action is combined with electro-chemo-mechanical interaction along the beam. The setup is able to work as sensor or actuator depending on the choice of control (and response) variables. Although quite idealized, this design allows for a qualitative investigation. In this paper we demonstrate the capability of the developed framework to simulate both the actuator and sensor modes. As proof of concept, we show that both modes of functionality can be captured using the developed framework. For the actuator mode, the predicted deformation is found to be in close agreement with experimental data. Further, the sensor-mode is found to agree with experimental data available in the literature.
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| 9. |
- Hultqvist, Adam, et al.
(författare)
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Sn1-xGexOy and Zn1-xGexOy by Atomic Layer Deposition-Growth Dynamics, Film Properties, and Compositional Tuning for Charge Selective Transport in (Ag,Cu)(In,Ga)Se2 Solar Cells
- 2023
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Ingår i: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 6:19, s. 9824-9836
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Tidskriftsartikel (refereegranskat)abstract
- Two inorganic electron-selective layers (ESLs), Sn1-xGexOy (TGO) and Zn1-xGexOy (ZGO), were developed by using atomic layer deposition (ALD) with in situ quartz crystal monitoring. To ensure (Ag,Cu)(In,Ga)Se-2 (ACIGS) solar cell compatibility, a 120 degrees C ALD process was developed for GeOy using Ge(N(CH3)(2))(4) and H2O as precursors. In the ALD supercycle approach, the GeOy ALD cycle was interchanged with either ZnO or SnOy cycles to deposit TGO and ZGO with varying conduction band positions (Ec), respectively. The material properties were experimentally verified using X-ray photoelectron spectroscopy and optical absorption and by employing these films as ESLs in ACIGS solar cells. There, the open-circuit voltage initially increased as the Ge content of the TGO and ZGO films increased due to the ESL E-c simultaneously shifting up from the low position in ZnO or SnOy to match the ACIGS E-c. As the Ge content increased further, the fill factor (FF) of these devices decreased since the ESL E-c became positioned significantly above the ACIGS E-c, forming an energy barrier as seen from ACIGS. As a result, the efficiency of the ACIGS solar cell peaked for an intermediate Ge content for both TGO and ZGO. Using good TGO and ZGO compositions in ACIGS solar cells gave efficiencies of up to 14.8 and 17.0%, respectively, which were lower than the reference best cell efficiencies of up to 19.5% for CdS and 18.2% for Zn1-xSnxOy (ZTO). ZGO was, however, able to shift its Ec further up than ZTO, making it a potent ESL for high-band-gap absorbers. Based on the results, we listed a few key properties that are required for a good ACIGS solar cell ESL and gave a few suggestions on how they are linked to the previous success of ZTO.
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| 10. |
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