Flexible Slots Research Articles

Scheduling and loading problem for multiple, identical dry kilns

The drying of sawn lumber is one of the major processing steps in sawmills with high production volumes. Existing publications on kiln drying analyse and improve technological conditions, while this paper focuses on the scheduling and loading planning with time availability of the individual dried packages. To improve dry kiln scheduling for multiple and identical kilns in large softwood processing sawmills, heuristic approaches are developed that generate kiln allocation plans according to existing production specifications. The aim is to minimise total tardiness for the drying of all sawn lumber packages while considering technological and capacity restrictions. These heuristics calculate the position, time and kiln for each package, thus solving scheduling and loading problems caused by capacity and stacking limitations. Several heuristic approaches are illustrated and tested with actual production data. In addition, the difference between static and dynamic scheduling for group and batch generation is analysed. Further improvements are possible through: drying of different lumber assortments in one batch, outsourcing the drying of special assortments or investing in supplementary kilns for drying smaller volumes within more flexible time slots.

Dynamic pricing of flexible time slots for attended home delivery

In e-commerce, customers are usually offered a menu of home delivery time windows of which they need to select exactly one, even though at least some customers may be more flexible. To exploit the flexibility of such customers, we propose to introduce flexible delivery time slots, defined as any combination of such regular time windows (not necessarily adjacent). In selecting a flexible time slot (out of a set of windows that form the flexible product), the customer agrees to be informed only shortly prior to the dispatching of the delivery vehicle in which regular time window the goods will arrive. In return for providing this flexibility, the company may offer the customer a reduced delivery charge and/or highlight the environmental benefits. Our framework also can accommodate customized flexible slots where customers can self-select a set of regular slots in which a delivery may take place.The vehicle routing problem (VRP) in the presence of flexible time slots bookings corresponds to a VRP with multiple time windows. We build on literature on demand management and vehicle routing for attended home delivery, as well as on flexible products. These two concepts have not yet been combined, and indeed the results from the flexible products literature do not carry over directly because future expected vehicle routing implications need to be taken into account. The main methodological contribution is the development of a tractable linear programming formulation that links demand management decisions and routing cost implications, whilst accounting for customer choice behavior. The output of this linear program provides information on the (approximate) opportunity cost associated with specific orders and informs a tractable dynamic pricing policy for regular and flexible slots. Numerical experiments, based on realistically-sized scenarios, indicate that expected profit may increase significantly depending on demand intensity when adding flexible slots rather than using only regular slots.

The prosody of formulaic expression in the IBM/Lancaster Spoken English Corpus

This article examines the distribution of the nucleus around selected formulaic expressions in the IBM/Lancaster Spoken English Corpus (SEC). The study reveals the presence of a positional bias such that formulaic expressions found at the end of intonation units are more likely to receive the nucleus than those found at the beginning. Amongst the formulaic expressions located at the end of intonation units, 70 percent have the nucleus assigned to the last lexical word of the expressions. For the remaining cases, the obligatory nuclei are found either on the lexical words immediately preceding the expressions or on the first words, the degree words or the flexible slots within the expressions. The study shows how prosodically annotated corpora may facilitate research on the prosody of formulaic expressions. At the same time, it also raises awareness of the issues confronting this new research avenue.

Second Language Learners' Contiguous and Discontiguous Multi‐Word Unit Use Over Time

ABSTRACTResearch has described the key role of formulaic language use in both written and spoken communication (Schmitt, 2004; Wray, 2002), as well as in relation to L2 learning (Ellis, Simpson–Vlach, & Maynard, 2008). Relatively few studies have examined related fixed and semifixed multi‐word units (MWUs), which comprise fixed parts with the potential for flexible slots in L2 learners' language use over time. Building upon the corpus linguistic methodology of concgramming and usage‐based linguistic research on a construction‐based developmental sequence in language acquisition, this article describes learners' multi‐word inventories through the analysis of a learner corpus of out‐of‐class instant messaging and blog use in a U.S. high school advanced placement Spanish language course. We examined this corpus using concgram analysis of phraseological tendencies to document related MWUs used in fixed and schematic fashion. Patterns in student language use are described in terms of meaningful permutations of constituency variation over time. Related patterns used by different learners are analyzed and discussed in light of methodological considerations in tracking second language use and the pedagogical implications of the concgramming approach to MWUs.