A construction and improvement heuristic for a liquefied natural gas inventory routing problem

We present a large scale ship routing and inventory management problem for a producer and distributor of liquefied natural gas (LNG). The problem contains multiple products, inventory and berth capacity at the loading port and a heterogeneous fleet of ships. The goal is to create an annual delivery program to fulfill the producer’s long-term contracts at minimum cost, while maximizing the revenue from selling LNG in the spot market. To solve this problem we have developed a construction and improvement heuristic (CIH).The CIH is a multi-start local search heuristic that constructs a set of solutions using a greedy insertion procedure. The solutions are then improved using either a first-descent neighborhood search, branch-and-bound on a mathematical formulation, or both. Tests on real-life instances show that the CIH provides good solutions in a short amount of time.     

Planar-Based Visual Inertial Navigation: Observability Analysis and Motion Estimation

In this paper, we address the problem of ego-motion estimation by fusing visual and inertial information. The hardware consists of an inertial measurement unit (IMU) and a monocular camera. The camera provides visual observations in the form of features on a horizontal plane. Exploiting the geometric constraint of features on the plane into visual and inertial data, we propose a novel closed form measurement model for this system. Our first contribution in this paper is an observability analysis of the proposed planar-based visual inertial navigation system (VINS). In particular, we prove that the system has only three unobservable states corresponding to global translations parallel to the plane, and rotation around the gravity vector. Hence, compared to general VINS, an advantage of using features on the horizontal plane is that the vertical translation along the normal of the plane becomes observable. As the second contribution, we present a state-space formulation for the pose estimation in the analyzed system and solve it via a modified unscented Kalman filter (UKF). Finally, the findings of the theoretical analysis and 6-DoF motion estimation are validated by simulations as well as using experimental data.     

Consumer adoption of RFID-enabled services. Applying an extended UTAUT model

In this article, an extended version of the unified theory of acceptance and use of technology (UTAUT) is applied to explore the significance of various antecedents of acceptance of eight versions of a radio frequency identification (RFID) enabled service. The results show significant influences from performance expectancy, effort expectancy and technology anxiety on attitude to use RFID-enabled services, while facilitating conditions and attitude to use both have significant influences on intention to use the services. Looking into potential moderating influences, gender moderates most of the relationships in the model while age and experience with identification technology do not seem to be relevant moderators. Exploring the potential moderating influence of context experience, experience of the service context is found to moderate some of the relationships in the model. Managerial implications point to the importance of developing useful and user-friendly services and of communicating the user friendliness to potential customers to avoid the potential negative influence of technology anxiety. Service development and market communication should be sensitive to gender and context experience.     

Double Mutant Cycles as a Tool to Address Folding,Binding, and Allostery

Quantitative measurement of intramolecular and intermolecular interactions in protein structure is an elusive task, not easy to address experimentally. The phenomenon denoted ‘energetic coupling’ describes short- and long-range interactions between two residues in a protein system. A powerful method to identify and quantitatively characterize long-range interactions and allosteric networks in proteins or protein–ligand complexes is called double-mutant cycles analysis. In this review we describe the thermodynamic principles and basic equations that underlie the double mutant cycle methodology, its fields of application and latest employments, and caveats and pitfalls that the experimentalists must consider. In particular, we show how double mutant cycles can be a powerful tool to investigate allosteric mechanisms in protein binding reactions as well as elusive states in protein folding pathways.     

Uncertainty and the ranking of economics journals

Scientometrics - Journal rankings often show significant changes compared to previous rankings. This gives rise to the question of how well estimated the rank of a journal is. In this contribution,...