Improved biological wastewater treatment and sludge characteristics by applying magnetic field to aerobic granules

Permanent magnets with non-uniform magnetic field and an electromagnet with 3–5 mT uniform magnetic field were applied to investigate their effects on both aerobic granulation and COD and ammonium removal in reactors with less than 7% coverage of magnetic field. It was found that both types of magnets had little influence on the granulation speed and the settling ability of granular sludge at the steady state. However, the maximum specific COD degradation rate and the maximum specific NH4+-N removal rate were increased by 45–54% and 30–50%, respectively, in the magnetic fields. Mean effluent COD with the electromagnet and the permanent magnet field, respectively, at the steady state, was 28 mg l?1 and 6 mg l?1, respectively, lower than the control at a statistical significance level of alpha = 0.05. No statistically significant increase in NH4+-N removal was observed at the steady state probably due to almost complete NH4+-N removal before the end of the cycle. In addition, it was found that extracellular polymeric substances in granular sludge with electromagnet were 77% more while soluble microbial products were much less compared with the control, suggesting a positively changed metabolism of granular sludge at steady state. The results in this study indicated that low-intensity magnetic field has a great potential to be applied in granular sludge for an improved wastewater treatment

Learning from Winners: A Strategic Perspective of Improving Freelancers’ Bidding Competitiveness in Crowdsourcing

The rapid growth of crowdsourcing grants freelancers unprecedented opportunities to materialize their expertise by bidding in specific tasks. Despite lowering freelancers’ participation costs, the bidding mechanism meanwhile induces intense competition, rendering it difficult for freelancers to submit competitive bids. Although previous research has disentangled several bidding strategies, scant attention was paid to whether and how freelancers should learn to adjust their bidding strategies and improve bidding competitiveness during the journey of participating in multiple tasks. To fill in this gap, we adapt a set of bidding strategies from auction literature into the crowdsourcing context. Leveraging the lens of vicarious learning, we advance that freelancers’ learning from winners on bidding strategies will enhance their bidding competitiveness, which is moderated by task complexity. Our preliminary results suggest a significant relationship between strategic learning and bidding competitiveness, along with the moderating effect of task complexity. Expected contributions and future schemes are discussed finally

Precise Orbit and Clock Products of Galileo, BDS and QZSS from MGEX Since 2018: Comparison and PPP Validation

In recent years, the development of new constellations including Galileo, BeiDou Navigation Satellite System (BDS) and Quasi-Zenith Satellite System (QZSS) have undergone dramatic changes. Since January 2018, about 30 satellites of the new constellations have been launched and most of the new satellites have been included in the precise orbit and clock products provided by the Multi Global Navigation Satellite System (Multi-GNSS) Experiment (MGEX). Meanwhile, critical issues including antenna parameters, yaw-attitude models and solar radiation pressure models have been continuously refined for these new constellations and updated into precise MGEX orbit determination and precise clock estimation solutions. In this context, MGEX products since 2018 are herein assessed by orbit and clock comparisons among individual analysis centers (ACs), satellite laser ranging (SLR) validation and precise point positioning (PPP) solutions. Orbit comparisons showed 3D agreements of 3–5 cm for Galileo, 8–9 cm for BDS-2 inclined geosynchronous orbit (IGSO), 12–18 cm for BDS-2 medium earth orbit (MEO) satellites, 24 cm for BDS-3 MEO and 11–16 cm for QZSS IGSO satellites. SLR validations demonstrated an orbit accuracy of about 3–4 cm for Galileo and BDS-2 MEO, 5–6 cm for BDS-2 IGSO, 4–6 cm for BDS-3 MEO and 5–10 cm for QZSS IGSO satellites. Clock products from different ACs generally had a consistency of 0.1–0.3 ns for Galileo, 0.2–0.5 ns for BDS IGSO/MEO and 0.2–0.4 ns for QZSS satellites. The positioning errors of kinematic PPP in Galileo-only mode were about 17–19 mm in the north, 13–16 mm in the east and 74–81 mm in the up direction, respectively. As for BDS-only PPP, positioning accuracies of about 14, 14 and 49 mm could be achieved in kinematic mode with products from Wuhan University applied

Experimental Study of Broadcatching in BitTorrent

Abstract—Broadcatching is a promising mechanism to improve the experience of BitTorrent users by automatically downloading files advertised through RSS feeds. However, though widely used, the mechanism itself has not been well studied. In this paper, we conducted extensive experiments on PlanetLab to evaluate the performance of Broadcatching under different typical scenarios. The results demonstrated the effectiveness of the Broadcatching: it reduces the average completion time and downloading failure ratio. It also improves the overall fairness of the system: the subscribers are encouraged to share more while downloading faster, which results in the increased share ratio. Our study is the first work to systematically evaluate the benefit of Broadcatching and sheds lights on how to improve performance of BitTorrrent by manipulating peer’s behavior like Broadcatching. I