Genetic algorithm for the cargo shunting cooperation between two hub-and-spoke logistics networks

Purpose: The overstocked goods flow in the hub of hub-and-spoke logistics network should be disposed of in time, to reduce delay loss and improve the utilization rate of logistics network resources. The problem we need to solve is to let logistics network cooperate by sharing network resources to shunt goods from one hub-and-spoke network to another hub-and-spoke network. Design/methodology/approach: This paper proposes the hub shunting cooperation between two hub-and-spoke networks. Firstly, a hybrid integer programming model was established to describe the problem, and then a multi-layer genetic algorithm was designed to solve it and two hub-and-spoke networks are expressed by different gene segments encoded by genes. The network data of two third-party logistics companies in southern and northern China are used for example analysis at the last step. Findings: The hub-and-spoke networks of the two companies were constructed simultaneously. The transfer cost coefficient between two networks and the volume of cargo flow in the network have an impact on the computation of hubs that needed to be shunt and the corresponding cooperation hubs in the other network. Originality/value: Previous researches on hub-and-spoke logistics network focus on one logistics network, while we study the cooperation and interaction between two hub-and-spoke networks. It shows that two hub-and-spoke network can cooperate across the network to shunt the goods in the hub and improve the operation efficiency of the logistics network.Peer Reviewe

Incremental Optimization of Hub and Spoke Network for the Spokes’ Numbers and Flow

Hub and spoke network problem is solved as part of a strategic decision making process which may have a profound effect on the future of enterprises. In view of the existing network structure, as time goes on, the number of spokes and the flow change because of different sources of uncertainty. Hence, the incremental optimization of hub and spoke network problem is considered in this paper, and the policy makers should adopt a series of strategies to cope with the change, such as setting up new hubs, adjusting the capacity level of original hubs, or closing some original hubs. The objective is to minimize the total cost, which includes the setup costs for the new hubs, the closure costs, and the adjustment costs for the original hubs as well as the flow routing costs. Two mixed-integer linear programming formulations are proposed and analyzed for this problem. China Deppon Logistics as an example is performed to present computational analysis, and we analyze the changes in the solutions driven by the number of spokes and the flow. The tests also allow an analysis to consider the effect of variation in parameters on network

One-pot fabrication of magnetic fluorinated carbon nanotubes adsorbent for efficient extraction of perfluoroalkyl carboxylic acids and perfluoroalkyl sulfonic acids in environmental water samples

Abstract(#br)Efficient extraction of perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) is challenging due to their highly fluorinated property. Based on the particular characters of PFCAs and PFSAs, a new type of magnetic fluorinated carbon nanotubes adsorbent (MFCA) for magnetic solid phase extraction (MSPE) was fabricated facilely using one-pot hydrothermal approach. The morphology, structure and magnetic properties of the prepared MFCA were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometry. It was observed that the resultant adsorbent possessed satisfactory superparamagnetism and saturation magnetism. Furthermore, the MFCA exhibited excellent enrichment performance for target PFCAs and PFSAs by means of fluorous-fluorous, hydrophobic and hydrogen bonding interactions. Under the most favorable preparation and extraction conditions, the proposed MFCA/MSPE was combined with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to quantify ultra trace target analytes in environmental water samples. The limits of detection (S/N = 3) of PFCAs and PFSAs were 0.010–0.036 ng/L and 0.024–0.50 ng/L, respectively. In addition, the introduced approach also displayed other features such as quick extraction procedure, wide linear dynamic ranges, excellent method precision and eco-friendliness. Finally, the concentrations of PFCAs and PFSAs in tap, river, lake and waste water samples were successfully measured by isotope internal standard calibration curve method

Six Thallus Surface Types of Coralline Algae with Descriptions of Two New Records of Amphiroa beauvoisii and Neogoniolithon setchellii in Sanya reef, China

Coralline algae are globally distributed calcifying species and play critical ecological roles to marine ecosystems by contributing significantly to their structural complexity and diversity. Thallus surface types of historical samples in Sanya coral reef reserve were studied based on the scanning electron microscope (SEM) method. Our results show six thallus surface types within the study area: Corallina-type, Jania-type, Leptophytum-type, Phymatolithon-type, Pneophyllum-type, and Spongites-type. The Phymatolithon-type is the dominant surface type in Sanya reefs. Two new record species in the region are described: Amphiroa beauvoisii and Neogoniolithon setchellii. Although thallus surface types provide useful diagnostics characters for distinguishing coralline algae at tribe or subfamily level, species identification needs to refer to the reproductive features. This is the first surface study of coralline algae in the South China Sea. This result provides the baseline data needed for the monitoring and management of reef-building organisms of coral reef in China

Study on Target Detection & Recognition Using Laser 3D Vision Systems for Automatic Ship Loader

This paper purposes a solution of the target detection and identification for automatic ship loader. For automatic ship loaders, the operation target should be detected and identified continuously and real-timely. By using the laser measurement systems (LMS), the ship cargo holds and the bulk cargo can be rebuilt as a group of 3D points. Then the image processing algorithm can identify the positions, sizes and shapes of the cargo holds and the bulk cargo from the 3D points. Based on the target information identified by the image processing algorithm, the ship loader can finish the loading operation automatically. At last, this paper describes and analyzes the experiment of the cargo height detection using LMS in Coal Terminal of Tianjin Port