INFLUENCE OF MAN-MACHINE RATIO ON SYSTEM PERFORMANCE OF ONE-PERSON-MULTI-MACHINE SERIES PRODUCTION LINE

The one-person-multi-machine assignment is a typical feature of lean production systems. The major disadvantage of this type of assignment is that it could cause system delay due to human failure. Therefore, it is important to analyze the degree of efficiency loss among machines caused by interference between operators and machines. In this paper, a methodology is developed based on the decomposition technique. The whole U-shape production line is modeled as several subsystems where the efficiency loss mentioned above can be treated as machine failure. Hence, each subsystem can be simplified as an unreliable workstation with a certain failure rate. With finite buffers between consecutive subsystems, the influence of human failure can be analyzed and verified with an industry-based case study. Data was collected from an automotive electronics plant as well as corresponding computational and simulation test results. Statistics show that the method developed in this paper will make contributions to solving industrial problems

An Automatic and Accurate Method for Marking Ground Control Points in Unmanned Aerial Vehicle Photogrammetry

Owing to the rapid development of unmanned aerial vehicle (UAV) technology and various photogrammetric software, UAV photogrammetry projects are becoming increasingly automated. However, marking ground control points (GCPs) in current UAV surveys still generally needs to be manually completed, which brings the problem of inefficiency and human error. Based on the characteristics of UAV photogrammetry, a novel type of circular coded target with its identification and decoding algorithm is proposed to realize an automatic and accurate approach for marking GCPs. UAV survey experiments validate the feasibility of the proposed method, which has comparative advantages in efficiency, robustness, and accuracy over traditional targets. Additionally, we conducted experiments to discuss the effects of projection size and viewing angle, number of coded bits, and environmental conditions on the proposed method. The results show that it can achieve robust identification and accurate positioning even under challenging conditions, and a smaller number of coded bits is recommended for better robustness

Batch-based traceability for pork: A mobile solution with 2D barcode technology

As an animal-derived food, pork provides Chinese consumers with important nutritional value. The frequent safety incidents related to pork-made food have led the government and public advocate that a traceability system is as an effective means of controlling food quality and safety. This paper thus introduces a mobile pork quality and safety tracing system based on 2D (two-dimensional) barcode (also known as QR code) technology. First, literature search and field observations are used to evaluate the business processes in pork supply chain and key traceability information in the system. Then, a mobile solution based on 2D barcode technology for information collection, transformation, and delivery is designed. Finally, a pilot implementation in Jilin Province’s Meat and Meat Products Safety Traceability and Regulatory Digitization Project is reported. The traceability system was integrated with the government supervision system to achieve the supervision and traceability of pork from source to table. Implementation results reveal that the system can realize batch-based traceability of pork, which greatly decreases traceability system cost. Additionally, the information verification mechanism between upstream and downstream players, as well as the full participation of consumers, enterprises, and the government, significantly improve the credibility of the traced information

A (1.4 + epsilon)-Approximation Algorithm for the 2-Max-Duo Problem

The maximum duo-preservation string mapping (Max-Duo) problem is the complement of the well studied minimum common string partition (MCSP) problem, both of which have applications in many fields including text compression and bioinformatics. k-Max-Duo is the restricted version of Max-Duo, where every letter of the alphabet occurs at most k times in each of the strings, which is readily reduced into the well known maximum independent set (MIS) problem on a graph of maximum degree Delta le 6(k-1). In particular, 2-Max-Duo can then be approximated arbitrarily close to 1.8 using the state-of-the-art approximation algorithm for the MIS problem. 2-Max-Duo was proved APX-hard and very recently a (1.6 + epsilon)-approximation was claimed, for any epsilon > 0. In this paper, we present a vertex-degree reduction technique, based on which, we show that 2-Max-Duo can be approximated arbitrarily close to 1.4

Study on Resourceful Treatment and Carbon Reduction Intensity of Metro Shield Slag: An Example of a Tunnel Interval of Shenzhen Line 13

At present, the scale of subway construction in Chinese cities has reached a new height, and the shield slag produced by it has also surged year by year. Untreated subway shield slag not only occupies the space resources of the country, but also carries CO2, which causes negative impacts on the environment and which, as a result, is not conducive to the realization of the goal of the national “double-carbon” strategy. Therefore, how to effectively manage the shield slag produced by subway construction has become a scientific problem that needs to be solved urgently. In order to scientifically dispose of metro shield slag and quantify the carbon reduction intensity of its disposal, based on the new shield slag integrated recycling technology, and taking a tunnel interval of Shenzhen Line 13 as an example, this study systematically sorted out the shield slag disposal process, clarified the management path of the on-site resource utilization of slag, and quantitatively compared the carbon emissions before and after the treatment as well as carbon reduction intensity. The results show that the on-site disposal process is basically feasible, and that, it is possible to achieve a shield structure slag reduction of resource products and mud cake water content of less than 40% of the target, in the case of 160,000 m3 of shield structure slag resource utilization after a total carbon reduction of about 4240.13 t CO2, of which each preparation of 1 m3 of recycled bricks can bring about a benefit of carbon reduction of 240.09 kg CO2. Compared with the conventional mud head truck slag disposal, shield structure slag resource utilization can save a utilization cost of about 10.4 million yuan, meaning that, in terms of economic and social levels, this method can achieve good benefits. This case verifies the feasibility of the new technology, and the results of the study can provide experience for other metro projects’ shield slag resource utilization, and provide stakeholders with a shield slag recycling management strategy for government departments to scientifically formulate metro shield slag management policy to provide data support

Highly hydrophilic carbon nanoparticles: uptake mechanism by mammalian and plant cells

As one of the carbon based materials, the potential application of carbon nanoparticles (CNPs) has emerged in the promotion of plant growth. However, knowledge on the biological mechanism of how the CNPs interact with plant cells is limited. In this study, nanostructures of CNPs were examined. The particles exhibited particulate morphology and their size distribution was in the range of 18 to 70 nm, with an average size of 30 nm. Hydrophilic groups of COOH and OH were present on the surface of CNPs, and CNPs showed the common feature of graphitic sp(2) hybridization carbons. The CNPs were determined to be biocompatible with these two cell lines, mammalian cells (A549 cells) and plant cells (BY-2 cells). The COOH groups on the surface of CNPs were functionalized via covalent binding with a fluorescent dye for improvement of the fluorescence. The fluorescent carbon nanoparticles (FCNPs) were found to cross the cell membrane and enter cells (A549 cells and BY-2 cells) in an energy-dependent manner. Subsequently, the mechanism of FCNPs interaction with the cell membrane was evaluated in the presence of inhibitors that specifically affect different endocytosis membrane proteins. The FCNPs mainly entered A549 cells through caveolin-mediated endocytosis and macropinocytosis, and clathrin-dependent endocytosis was also involved in the transportation of the FCNPs. Clathrin-independent endocytosis mediated in the internalization of FCNPs in BY-2 cells. The way FCNPs entering cells will provide a fundamental understanding of the influence of CNPs on cell membrane

Revisiting Late Pleistocene Loess–Paleosol Sequences in the Azov Sea Region of Russia : Chronostratigraphy and Paleoenvironmental Record

Loess-paleosol sequences are the most intensively studied terrestrial archives used for the reconstruction of Late Pleistocene environmental and climatic changes in the Azov Sea region, southwest Russia. Here we present a refined chronostratigraphy and a multiproxy record of Late Pleistocene environmental dynamics of the most complete and representative loess–paleosol sequences (Beglitsa and Chumbur-Kosa sections) from the Azov Sea region. We propose a new chronostratigraphy following the Chinese and Danubean loess stratigraphic models that refines the subdivision of the Last Interglacial paleosol (S1) complex in two Azov Sea sites, resolve the uncertainty of the stratigraphic position of the weakly developed paleosol (L1SSm) in Beglitsa section, and allow for direct correlation of the Azov Sea sections with those in the Danube Basin and the Chinese Loess Plateau. More importantly, it may serve as a basis for better constraining local and regional chronostratigraphic correlations, and facilitate the interpretation of climatic connections and possible forcing mechanisms responsible for the climatic trends in the region. In addition, a general succession of environmental dynamics is reconstructed from these two vital sections, which is broadly consistent with other loess records in the Dnieper Lowland and Lower Danube Basin, demonstrating similar climatic trends at Glacial–Interglacial time scales. Furthermore, our results have important implications for the chronostratigraphic representativeness of Beglitsa as a key regional loess section and for the reconstruction of the temporal and spatial evolution of Late Pleistocene climate in the Azov Sea region