Influence of Bionic Circular Groove Blade Surface on Wear Performance

In order to improve the anti-wear performance of a double-vane self-priming centrifugal pump during two-phase flow transfer, the construction of a streamline groove structure at the outlet end of the suction side of the vane, based on the bionic principle, is proposed. Different pump characteristics are analysed to investigate the effect of different bionic groove spacing on the resistance to particle wear and the mechanism of improvement of the bionic grooves. The results show that the effect of the bionic blades on the hydraulic characteristics of the pump is within the allowable error (±1.4%). The circular groove structure with different spacing produces a difference in the pressure distribution on the blade. At the same particle concentration, with the increase in the groove spacing distance, the average wear of the blades first decreases and then increases; the average wear rate at the spacing of 7 mm is the smallest. At a particle concentration of 90 kg/m3, the average wear rate at a groove spacing of 7 mm is ~0.63 × 10−4 kg/s∙m2, and the wear area is mainly found in the middle of the blade. The reason why the bionic blade improves the anti-wear performance of the pump is due to the reverse vortex zone in the groove, which changes the particle trajectory and collision frequency. The bionic grooves with a diameter of 2 mm and a spacing of 7 mm significantly reduce the average wear rate of the pump at different particle concentrations, while maintaining hydraulic performance

Enhanced Heavy Metal Tolerance and Accumulation by Transgenic Sugar Beets Expressing Streptococcus thermophilus StGCS-GS in the Presence of Cd, Zn and Cu Alone or in Combination.

Phytoremediation is a promising means of ameliorating heavy metal pollution through the use of transgenic plants as artificial hyperaccumulators. A novel Streptococcus thermophilus γ-glutamylcysteine synthetase-glutathione synthetase (StGCS-GS) that synthesizes glutathione (GSH) with limited feedback inhibition was overexpressed in sugar beet (Beta vulgaris L.), yielding three transgenic lines (s2, s4 and s5) with enhanced tolerance to different concentrations of cadmium, zinc and copper, as indicated by their increased biomass, root length and relative growth compared with wild-type plants. Transgenic sugar beets accumulated more Cd, Zn and Cu ions in shoots than wild-type, as well as higher GSH and phytochelatin (PC) levels under different heavy metal stresses. This enhanced heavy metal tolerance and increased accumulation were likely due to the increased expression of StGCS-GS and consequent overproduction of both GSH and PC. Furthermore, when multiple heavy metal ions were present at the same time, transgenic sugar beets overexpressing StGCS-GS resisted two or three of the metal combinations (50 μM Cd-Zn, Cd-Cu, Zn-Cu and Cd-Zn-Cu), with greater absorption in shoots. Additionally, there was no obvious competition between metals. Overall, the results demonstrate the explicit role of StGCS-GS in enhancing Cd, Zn and Cu tolerance and accumulation in transgenic sugar beet, which may represent a highly promising new tool for phytoremediation

Dynamic coverage control design of multi-agent systems under ellipse sensing regions

summary:This paper studies the dynamic coverage control problem for cooperative region reconnaissance where a group of agents are required to reconnoitre a given region. The main challenge of this problem is that the sensing region of each agent is an ellipse. This modeling results in asymmetric(directed) interactions among agents. First, the region reconnaissance is formulated as a coverage problem, where each point in the given region should be surveyed until a preset level is achieved. Then, a coverage control law is designed that minimizes coverage performance index by finite switches between nominal control laws and perturbation control law. Finally, numerical simulations are provided to indicate the efficiency of the proposed control law

Understanding bike trip patterns leveraging bike sharing system open data

International audienceBike sharing systems are booming globally as a green and flexible transportationmode, but the flexibility also brings difficulties in keeping the bike stations balanced with enough bikes and docks. Understanding the spatio-temporal bike trip patterns in a bike sharing system, such as the popular trip origins and destinations during rush hours, is important for researchers to design models for bike scheduling and station management. However, due to privacy and operational concerns, bike trip data are usually not publicly available in many cities. Instead, the station feeds about real-time bike and dock number in stations are usually public, which we refer to as bike sharing system open data. In this paper, we propose an approach to infer the spatio-temporal bike trip patterns from the public station feeds. Since the number of possible trips (i.e., origin-destination station pairs) is much larger than the number of stations, we define the trip inference as an ill-posed inverse problem. To solve this problem, we identify the sparsity and locality properties of bike trip patterns, and propose a sparse and weighted regularization model to impose both properties in the solution. We evaluate our method using real-world data fromWashington, D.C. and New York City. Results show that our method can effectively infer the spatio-temporal bike trip patterns and outperform the baselines in both cities

Container Throughput Estimation Leveraging Ship GPS Traces and Open Data

Traditionally, the port container throughput, a crucial measurement of regional economic development, was manually collected by port authorities. This requires a large amount of human effort and often delays publication of this important figure. In this paper, by leveraging ubiquitous positioning techniques and open data, we propose a two-phase approach to estimation of port container throughput in real-time. First, we obtain the number of container ships arriving at berth by analyzing the ships' GPS traces. Then we estimate the throughput of each ship, in terms of number of containers transshipped, by considering the ship's berthing time, capacity, length, breadth, and crane operation performance, as extracted from different data sources. Evaluation results using real-world datasets from Hong Kong and Singapore show that the proposed approach not only estimates the container throughput quite accurately, but also outperforms the baseline method significantly

Influence of Bionic Circular Groove Blade Surface on Wear Performance

In order to improve the anti-wear performance of a double-vane self-priming centrifugal pump during two-phase flow transfer, the construction of a streamline groove structure at the outlet end of the suction side of the vane, based on the bionic principle, is proposed. Different pump characteristics are analysed to investigate the effect of different bionic groove spacing on the resistance to particle wear and the mechanism of improvement of the bionic grooves. The results show that the effect of the bionic blades on the hydraulic characteristics of the pump is within the allowable error (±1.4%). The circular groove structure with different spacing produces a difference in the pressure distribution on the blade. At the same particle concentration, with the increase in the groove spacing distance, the average wear of the blades first decreases and then increases; the average wear rate at the spacing of 7 mm is the smallest. At a particle concentration of 90 kg/m3, the average wear rate at a groove spacing of 7 mm is ~0.63 × 10−4 kg/s∙m2, and the wear area is mainly found in the middle of the blade. The reason why the bionic blade improves the anti-wear performance of the pump is due to the reverse vortex zone in the groove, which changes the particle trajectory and collision frequency. The bionic grooves with a diameter of 2 mm and a spacing of 7 mm significantly reduce the average wear rate of the pump at different particle concentrations, while maintaining hydraulic performance