A fast simulated annealing method for batching precedence-constrained customer orders in a warehouse

Batching customer orders in a warehouse can result in considerable savings in order pickers’ travel distances. Many picker-to-parts warehouses have precedence constraints in picking a customer order. In this paper a joint order-batching and picker routing method is introduced to solve this combined precedence-constrained routing and order-batching problem. It consists of two sub-algorithms: an optimal A^∗-algorithm for the routing; and a simulated annealing algorithm for the batching which estimates the savings gained from batching more than two customer orders to avoid unnecessary routing. For batches of three customer orders, the introduced algorithm produces results with an error of less than 1.2% compared to the optimal solution. It also compares well to other heuristics from literature. A data set from a large Finnish order picking warehouse is rerouted and rebatched resulting in savings of over 5000 kilometres or 16% in travel distance in 3 months compared to the current method.     

Consistent cost sharing

A new concept of consistency for cost sharing solutions is discussed, analyzed, and related to the homonymous and natural property within the rationing context. Main result is that the isomorphism in Moulin and Shenker (J Econ Theory 64:178–201, 1994) pairs each additive and consistent single-valued mechanism with a corresponding monotonic and consistent rationing method. Then this answers the open question in Moulin (Econometrica 68:643–684, 2000; Handbook of social choice and welfare. Handbooks in economics, pp 289–357, 2002) whether such notion for cost sharing exists. The conclusion is that renown solutions like the average and serial cost sharing mechanisms are consistent, whereas the Shapley–Shubik mechanism is not. Average cost sharing is the only strongly consistent element in this class. The two subclasses of incremental and parametric cost sharing mechanisms are further analyzed as refinement of the main result.     

Bisphosphine based hetero-capsules for the encapsulation of transition metals

Just mixing of solutions of tetracationic diphosphine ligands and tetraanionic calix[4]arene building blocks leads to the formation of supramolecular heterocapsules that coordinate a palladium metal within the cavity of the assembly, giving rise to a new class of potential supramolecular transition metal catalysts.     

High-resolution electron tomography study of an industrial Ni-Mo/gamma-Al2O3 hydrotreating catalyst

The growing demand for high-quality transportation fuels requires their cost-effective production by hydrodesulfurization of crude oils using heterogeneous catalysts. To study the three-dimensional (3D) structure of such a commercial, sulfided Ni-Mo/gamma-Al2O3 catalyst, electron tomography was applied. The MoS2 particles form an interconnected complex structure within the mesopores of the alumina support. Spatial organization, morphology, and orientation of the MoS2 particles in the pores were resolved with sufficient accuracy to display the 6-A-spaced MoS2 crystal planes. The proximity of the MoS2 edge planes and more loosely interacting MoS2 basal planes to the alumina support showed the presence of pores smaller than 3 nm, which was confirmed by physisorption experiments. The actual shape of the MoS2 particles cannot be described by simple models as derived from studies on model catalysts. Electron tomography is a unique tool to study the actual 3D structure of complex industrial catalysts with sub-nanometer resolution.     

A Twistorial Approach to Integrability in SYM

While the achievements in the study of Super Yang‐Mills through the application of integrability are impressive, the precise origins of the exact solvability remain shrouded in mystery. In this note, we propose that viewing the problem through the lens of twistor theory should help to clarify the reasons for integrability. We illustrate the power of this approach by rederiving the model's one‐loop spin chain dilatation operator in the SO(6) sector.     

Linear production with transport of products,resources and technology

This paper considers linear production situations with a finite number of production facilities, each with its own production technology and market prices. The economic agents control resources at the different facilities. Transport of resources, products and technology is restricted. Sufficient conditions for the corresponding TU-game to be balanced are discussed. In this we extend the results of Owen (1975), Granot (1986) and Curiel, Derks, and Tijs (1989). An example is presented in some detail.This research is sponsored by the Foundation for the Promotion of Research in Economic Sciences, which is part of the Dutch Organization for Scientific Research (NWO).     

Diphosphine Capsules for Transition‐Metal Encapsulation

Self‐assembly and characterization of novel heterodimeric diphosphine capsules formed by multiple ionic interactions and composed of one tetracationic diphosphine ligand and one complementary tetraanionic calix[4]arene are described. Encapsulation of a palladium atom within a diphosphine capsule is achieved successfully by using the metal complex of the tetracationic diphosphine ligand for the assembly process. In this templated approach to metal encapsulation, the transition‐metal complex is an integrated part of the capsule with the transition metal located inside the capsule and is not involved in the assembly process. We present two approaches for capsule assembly by mixing solutions of the precharged building blocks in methanol and mixing solutions of the neutral building blocks in methanol. The scope of the diphosphine capsules and the metallodiphosphine capsules is easily extended by applying tetracationic diphosphine ligands with different backbones (ethylene, diphenyl ether, and xanthene) and cationic binding motifs (p‐C₆H₄‐CH₂‐ammonium, m‐C₆H₄‐ammonium, and m‐C₆H₄‐guanidinium). These tetracationic building blocks with different flexibilities and shapes readily associate into capsules with the proper capsular structure, as is indicated by ¹H NMR spectroscopy, 1D NOESY, ESI‐MS, and modeling studies.     

Validity of the Einstein relation in disordered organic semiconductors

It is controversial whether energetic disorder in semiconductors is already sufficient to violate the classical Einstein relation, even in the case of thermal equilibrium. We demonstrate that the Einstein relation is violated only under nonequilibrium conditions due to deeply trapped carriers, as in diffusion-driven current measurements on organic single-carrier diodes. Removal of these deeply trapped carriers by recombination unambiguously proves the validity of the Einstein relation in disordered semiconductors in thermal (quasi)equilibrium.     

The forgotten sons: Warehousing systems for brick-and-mortar retail chains

Warehouses are an inevitable component in any supply chain and a vividly investigated object of research. Much attention, however, is absorbed by warehousing systems dedicated to the special needs of online retailers in the business-to-consumer segment. Due to the ever increasing sales volumes of e-commerce this focus seems self-evident, but a much larger fraction of retail sales are still realized by traditional brick-and-mortar stores. The special needs of warehouses servicing these stores are focused in this paper. While e-commerce warehouses face low-volume-high-mix picking orders, because private households tend to order just a few pieces per order from a large assortment, distribution centers of retail chains rather have to process high-volume-low-mix orders. We elaborate the basic requirements within both business segments and identify suited warehousing systems for brick-and-mortar stores (e.g., fully-automated case picking). The setup of each identified warehousing system is described, elementary decision problems are discussed, and the existing literature is surveyed. Furthermore, we identify future research needs.