PuzzleFlex: kinematic motion of chains with loose joints

This paper presents a method of computing free motions of a planar assembly of rigid bodies connected by loose joints. Joints are modeled using local distance constraints, which are then linearized with respect to configuration space velocities, yielding a linear programming formulation that allows analysis of systems with thousands of rigid bodies. Potential applications include analysis of collections of modular robots, structural stability perturbation analysis, tolerance analysis for mechanical systems, and formation control of mobile robots.Comment: Accepted at the 2020 IEEE International Conference on Robotics and Automation (ICRA

Discovery of Plant Viruses From Tea Plant (Camellia sinensis (L.) O. Kuntze) by Metagenomic Sequencing

The tea plant (Camellia sinensis (L.) O. Kuntze) is an economically important woody species. In this study, we collected 26 tea plant samples with typical discoloration symptoms from different tea gardens and performed metagenomic analysis based on next-generation sequencing. Homology annotation and PCR sequencing validation finally identified seven kinds of plant viruses from tea plant. Based on abundance distribution analysis, the two most abundant plant viruses were highlighted. Genetic characterization suggested that they are two novel virus species with relatively high homology to Blueberry necrotic ring blotch virus and American plum line pattern virus. We named the newly discovered viruses tea plant necrotic ring blotch virus (TPNRBV) and tea plant line pattern virus (TPLPV). Evolutionary relationship analysis indicated that TPNRBV and TPLPV should be grouped into the Blunervirus and the Ilarvirus genera, respectively. TPLPV might have same genome activation process with known ilarviruses based on sequence analysis. Moreover, specific primers for both viruses detection were designed and validated. The symptoms and ultrastructure of TPNRBV infected leaves were first recorded. Virus detections in the symptomatic and asymptomatic tissues from field plants showing tea plant necrotic ring blotch disease suggest that TPNRBV has a systemic movement feature. In summary, we first identified seven kinds of putative plant viruses by metagenomic analysis and report two novel viruses being latent pathogens to tea plant. The results will advance our understanding of tea plant virology and have significance for the genetic breeding of tea plants in the future

Prediction of Air Pollutants Concentration Based on an Extreme Learning Machine: The Case of Hong Kong

With the development of the economy and society all over the world, most metropolitan cities are experiencing elevated concentrations of ground-level air pollutants. It is urgent to predict and evaluate the concentration of air pollutants for some local environmental or health agencies. Feed-forward artificial neural networks have been widely used in the prediction of air pollutants concentration. However, there are some drawbacks, such as the low convergence rate and the local minimum. The extreme learning machine for single hidden layer feed-forward neural networks tends to provide good generalization performance at an extremely fast learning speed. The major sources of air pollutants in Hong Kong are mobile, stationary, and from trans-boundary sources. We propose predicting the concentration of air pollutants by the use of trained extreme learning machines based on the data obtained from eight air quality parameters in two monitoring stations, including Sham Shui Po and Tap Mun in Hong Kong for six years. The experimental results show that our proposed algorithm performs better on the Hong Kong data both quantitatively and qualitatively. Particularly, our algorithm shows better predictive ability, with R 2 increased and root mean square error values decreased respectively

Transformation of Inclusions in Solid GCr15 Bearing Steels During Heat Treatment

Laboratory heating experiments with a varied holding time of GCr15 bearing steels at 1498 K were performed to study the transformation of inclusions in solid GCr15 bearing steels during high temperature diffusion processes. Heating experiments at 1573 and 1648 K were also carried out to study the effect of these heating temperatures. Experimental results showed that inclusions transformed from Al2O3-CaO-(MgO) to Al2O3-CaS-(MgO-CaO) when the heat treatment was in the range of 1498 to 1648 K due to reactions between Al and S in the steel matrix and CaO in the inclusions. This is in good agreement with thermodynamic calculations. Moreover, the size of the inclusions hardly changed after heat treatment. The transformation rate of the inclusions depended strongly on both the heating temperature and the size of the inclusions. Kinetic analyses on the transformation of inclusions during heat treatment were performed based on a simplified analytical model. The mass transfer coefficients of CaO and CaS in inclusions were calculated, which ranged from 0.73 × 10−10 to 4.48 × 10−10 m/s

Innovation and survival of exporters: A contingency perspective

We challenge the traditional view that innovations always help exporters prosper in competitive international market, by developing and testing the premise that the relationship between innovation and export performance is contingent on some important firm-specific idiosyncrasies. With a large dataset of Chinese firms, the empirical results demonstrate that innovation could be detrimental to exporter survival. Such negative effect is more pronounced for firms that have weak profitability and high outstanding receivables, and also for those without foreign ownership. Nonetheless, we also observe a positive relationship between innovation and survival in highly profitable exporters. By identifying the negative rather than conventionally assumed positive effect of innovation, and the conditions under which innovation facilitates or impedes exporter survival, this paper contributes to the literature on the relationship between innovation and export in the context of emerging markets. Our findings have important implications for how managers develop innovation strategy to compete in the export market

Comparison of the efficacy and safety of Transarterial chemoembolization with and without Apatinib for the treatment of BCLC stage C hepatocellular carcinoma

Abstract Background Hepatocellular carcinoma (HCC) is a common cancer worldwide, with a poor prognosis. Most patients are diagnosed at advanced stages and are only eligible for palliative therapy. Therefore, this study aimed to evaluate the safety and efficacy of transcatheter arterial chemoembolization (TACE) combined with apatinib (TACE-apatinib) treatment and TACE-alone treatment for Barcelona Clinic Liver Cancer stage C HCC. Methods We retrospectively reviewed 80 consecutive patients with BCLC stage C HCC who received TACE-apatinib or TACE-alone as the initial treatment. We compared the clinical and laboratory outcomes, imaging findings at 1 and 3 months after TACE, tumor response, time to progression (TTP), overall survival (OS), and adverse events between both groups. Results The overall response rate was higher in the TACE-apatinib group than in the TACE-alone group at 1 and 3 months after treatment (66.7% vs 39.6%, respectively, P = 0.020; 45.8% vs 17.6%, respectively, P = 0.021). The median TTP and OS in the TACE-apatinib group were longer than those of the TACE-alone group (TTP: 6.3 months vs 3.5 months, respectively, P = 0.002; OS: 13.0 months vs 9.9 months, respectively, P = 0.041). Apatinib-associated side effects such as hypertension, hand-foot syndrome, oral ulcers, proteinuria, and diarrhea were more prevalent in the TACE-apatinib group than in TACE-alone group (P < 0.05). Conclusion Compared to TACE-alone treatment, TACE-apatinib increased the TTP, OS, and tumor-response rate at 1 and 3 months after treatment of BCLC stage C HCC without any significant increase in severe adverse events

Dependence of the Clogging Possibility of the Submerged Entry Nozzle during Steel Continuous Casting Process on the Liquid Fraction of Non-Metallic Inclusions in the Molten Al-Killed Ca-Treated Steel

In the current study, the nozzle clogging behavior and inclusion composition in Al-killed Ca-treated steels were observed to investigate the relationship between the liquid fraction of non-metallic inclusions and the clogging possibility of the submerged entry nozzle. Clogging materials were mainly MgO-Al2O3 with less than 20% liquid phases, while most of the inclusions were full liquid CaO-Al2O3-MgO in tundish at the casting temperature. Thus, it was proposed that the nozzle clogging can be effectively avoided by modification of solid inclusions to partial liquid ones rather than full liquid ones. There was a critical value of liquid fraction of inclusions causing the nozzle clogging. A critical condition of the inclusion attachment on the nozzle wall was a function of cos&theta;N&minus;S+cos&theta;I&minus;S&lt;0. With the increase of T.Ca content in steel, the evolution route of inclusions was solid MgO-Al2O3&rarr;liquid CaO-Al2O3-MgO&rarr;solid CaS and CaO. To avoid the clogging of the submerged entry nozzle (SEN) under the current casting condition, the appropriate T.Ca concentration range in Al-killed Ca-treated steels can be enlarged from the 100% liquid inclusion zone of 10&ndash;14 ppm to the 20% liquid inclusion zone of 4&ndash;38 ppm