Time-dependent performance approximation of truck handling operations at an air cargo terminal

This paper provides an analytical solution for the time-dependent performance evaluation of truck handling operations at an air cargo terminal. The demand for loading and unloading operations is highly time-dependent and stochastic for two classes of trucks. Two heterogeneous handling facilities with multiple servers are available to handle trucks assuming exponentially distributed processing times. Trucks are routed to a handling facility depending on the current state of the system upon arrival. To approximate the time-dependent behavior of such heterogeneous queueing systems, we develop a stationary backlog-carryover (SBC) approach. A numerical study compares this approach with simulations and demonstrates its applicability to real-world input data

Maximal D=2 supergravities from higher dimensions

We develop in detail the general framework of consistent Kaluza-Klein truncations from D=11 and type II supergravities to gauged maximal supergravities in two dimensions. In particular, we unveil the complete bosonic dynamics of all gauged maximal supergravities that admit a geometric uplift. Our construction relies on generalised Scherk-Schwarz reductions of E$_9$ exceptional field theory. The application to the reduction of D=11 supergravity on $S^8\times S^1$ to SO(9) gauged supergravity is presented in a companion paper.Comment: 46 pages plus appendice

Consistent truncation of eleven-dimensional supergravity on S8×S1S^8\times S^1

Eleven-dimensional supergravity on $S^8\times S^1$ is conjectured to be dual to the M-theory matrix model. We prove that the dynamics of a subset of fluctuations around this background is consistently described by D=2 SO(9) gauged maximal supergravity. We provide the full non-linear uplift formulae for all bosonic fields. We also present a further truncation to the SO(3)$\times$SO(6) invariant sector and discuss its relation to the BMN matrix model at finite temperature. The construction relies on the framework of generalised Scherk-Schwarz reductions, established for E$_9$ exceptional field theory in a companion paper. As a by-product, we severely constrain the most general gauge deformations in D=2 admitting an uplift to higher dimensions.Comment: 40 pages + appendice

Making the Newsvendor Smart – Order Quantity Optimization with ANNs for a Bakery Chain

Accurate demand forecasting is particularly crucial for products with short shelf life like bakery products. Over- and underestimation of customer demand affects not only profit margins of bakeries but is also responsible for 600,000 metric tons of food waste every year in Germany. To solve this problem, we develop an IT artifact based on artificial neural networks, which is automating the manual order process and capable of reducing costs as well as food waste. To test and evaluate our artifact, we cooperated with an SME bakery chain from Germany. The bakery chain runs 40 points of sale (POS) in southern Germany. After algorithm based reconstructing and cleaning of the censored sales data, we compare two different data-driven newsvendor approaches for this inventory problem. We show that both models are able to significantly improve the forecast quality (cost savings up to 30%) compared to human planners

Sufficient optimality conditions for bilinear optimal control of the linear damped wave equation

In this paper we discuss sufficient optimality conditions for an optimal control problem for the linear damped wave equation with the damping parameter as the control. We address the case that the control enters quadratic in the cost function as well as the singular case that the control enters affine. For the non-singular case we consider strong and weak local minima , in the singular case we derive sufficient optimality conditions for weak local minima. Thereby, we take advantage of the Goh transformation applying techniques recently established in Aronna, Bonnans, and Kröner [Math. Program. 168(1):717–757, 2018] and [INRIA research report, 2017]. Moreover, a numerical example for the singular case is presented

Structure of the VipA/B Type VI Secretion Complex Suggests a Contraction-State-Specific Recycling Mechanism

The bacterial type VI secretion system is a multicomponent molecular machine directed against eukaryotic host cells and competing bacteria. An intracellular contractile tubular structure that bears functional homology with bacteriophage tails is pivotal for ejection of pathogenic effectors. Here, we present the 6 A cryoelectron microscopy structure of the contracted Vibrio cholerae tubule consisting of the proteins VipA and VipB. We localized VipA and VipB in the protomer and identified structural homology between the C-terminal segment of VipB and the tail-sheath protein of T4 phages. We propose that homologous segments in VipB and T4 phages mediate tubule contraction. We show that in type VI secretion, contraction leads to exposure of the ClpV recognition motif, which is embedded in the type VI-specific four-helix-bundle N-domain of VipB. Disaggregation of the tubules by the AAA+ protein ClpV and recycling of the VipA/B subunits are thereby limited to the contracted state

Dispute Settlement for Labour Provisions in EU Free Trade Agreements: Rethinking Current Approaches

While labour provisions have been inserted in a number of EU free trade agreements (FTAs), extant clauses are widely perceived as ineffective. This article argues that there is a need to rethink the dispute settlement mechanisms related to labour provisions if their effectiveness is to be increased. It proceeds in three steps. First, we look at the current state of the art of labour provisions in EU FTAs in terms of legal design and practice and argue that the current arrangements are ill-equipped to foster compliance with labour standards. Second, we explore avenues to enhance the design of FTA labour provisions by reconsidering basic elements of the dispute settlement structure. Examining US FTA labour provisions, we highlight the importance of a formal complaint mechanism, on the one hand, and the availability of economic sanctions, on the other. Based on a review of existing practice, we contend, however, that these elements alone are not sufficient to effectively enforce FTA labour provisions. We argue that for FTA labour provisions to be effective, the current state-to-state model of dispute settlement needs to be complemented by a third-party-state dimension and that, additionally, there are good reasons to consider a third party–third party dispute settlement component. We ground these reflections in experiences with already existing instruments in other areas, namely investor-state dispute settlement and voluntary sustainability standards. Thirdly, we discuss options to better connect the dispute settlement mechanisms of FTA labour provisions to other international instruments for labour standards protection with a view to creating synergies and avoiding fragmentation between the different regimes. The focus here is on the International Labour Organization’s supervisory mechanism and the framework of the OECD Guidelines for Multinational Enterprises

Monitoring of multiple fabrication parameters of electrospun polymer fibers using mueller matrix analysis

Electrospun polymer fiber mats feature versatile applications in tissue engineering, drug delivery, water treatment and chemical processes. The orientation of fibers within these mats is a crucial factor that significantly influences their properties and performance. However, the analysis of fiber samples using scanning electron microscopy (SEM) has limitations such as time consumption, fixed assembly, and restricted field of vision. Therefore, a fast and reliable method for qualitative measurements of fiber orientation is required. Mueller matrix polarimetry, a well-established method for measuring orientation of chemical and biological species, was employed in this case. We investigated the effect of four important parameters of the electrospinning process, namely collector speed, applied voltage, needle-to-collector distance, and solution concentration, on fiber orientation using Mueller matrix polarimetry thus extending the range of parameters analyzed. Measurements were performed using two extreme values and a central optimized value for each fabrication parameter. Changes in matrix values were observed for each fabrication parameter, and their correlation with fiber orientation was analyzed based on the Lu-Chipman decomposition. The results were compared with SEM images, which served as the ground truth, and showed overall good agreement. In the future, the analysis of electrospun polymer fibers can be done by using Mueller matrix polarimetry as alternative to current technology and fabrication parameters, including solution concentration for the first time in this context and the production can quickly be adjusted based on the outcome of the measurements