Numerical simulation on the impact dynamics of a novel rotation air hammer and experimental research

Novel rotation air hammer (NRAH) is a rock-breaking tool in the gas drilling. The rock-breaking ability of the NRAH is mainly from the collision between piston and drill bit in it. The collision makes the piston and the drill bit suffer from a high instantaneous impact stress, so that they are prone to failure. Thus, both of them are not only the most crucial parts of the NRAH, but also the easily damaged parts. So it is necessary to analyze the impact stress in them and optimize their structure to improve the security and reliability. First of all, we analyzed the working mechanism of the NRAH to understand motion and structure of the piston and the drill bit. Then we used the LS-DYNA program to analyze impact dynamics problem of the piston and the drill bit to obtain their stress change rule in the impact process. According to the structure optimization, the security coefficient of the piston and the drill bit has been obviously improved. Moreover, their energy conversion regulations were studied in the impact process of the NRAH and the last impacting velocity of the piston was computed, which can provide helpful for effective application of this tool in the field. Finally, based on the experimental study on the NRAH after the optimization, we found that its function had satisfied the design requirements as well as overall performance was improved

Loop Formulas for Description Logic Programs

Description Logic Programs (dl-programs) proposed by Eiter et al. constitute an elegant yet powerful formalism for the integration of answer set programming with description logics, for the Semantic Web. In this paper, we generalize the notions of completion and loop formulas of logic programs to description logic programs and show that the answer sets of a dl-program can be precisely captured by the models of its completion and loop formulas. Furthermore, we propose a new, alternative semantics for dl-programs, called the {\em canonical answer set semantics}, which is defined by the models of completion that satisfy what are called canonical loop formulas. A desirable property of canonical answer sets is that they are free of circular justifications. Some properties of canonical answer sets are also explored.Comment: 29 pages, 1 figures (in pdf), a short version appeared in ICLP'1

Identifying and Compensating for Feature Deviation in Imbalanced Deep Learning

We investigate learning a ConvNet classifier with class-imbalanced data. We found that a ConvNet significantly over-fits the minor classes that do not have sufficient training instances, which is quite opposite to a traditional machine learning model like logistic regression that often under-fits minor classes. We conduct a series of analysis and argue that feature deviation between the training and test instances serves as the main cause. We propose to incorporate class-dependent temperatures (CDT) in learning a ConvNet: CDT forces the minor-class instances to have larger decision values in the training phase, so as to compensate for the effect of feature deviation in the test data. We validate our approach on several benchmark datasets and achieve promising performance. We hope that our insights can inspire new ways of thinking in resolving class-imbalanced deep learning

MicroRNAs in lung cancer

Lung cancer (LC) is a serious public health problem responsible for the majority of cancer deaths and comorbidities in developed countries. Tobacco smoking is considered the main risk factor for LC; however, only a few smokers will be affected by this cancer. Current screening methods are focused on identifying the early stages of this malignancy. Thus, new data concerning the roles of microRNA alterations in inflammation, epithelial-mesenchymal transition and lung disease have increased hope about LC pathogenesis, diagnosis, treatment and prognosis. MicroRNA mechanisms include angiogenesis promotion, cell cycle regulation by modulating cellular proliferation and apoptosis, and migration and invasion inhibition. In this context, this manuscript reviews the current information about many important microRNAs as they relate to the initiation and progression of LC.info:eu-repo/semantics/publishedVersio

Hawking radiation of black holes in the z=4z = 4 Horava-Lifshitz gravity

We investigate the Hawking radiation of 3+1 and 4+1 dimensional black holes in the $z = 4$ Horava-Lifshitz gravity with fermion tunnelling. It turns out that the Hawking temperatures are recovered and are in consistence with those obtained by calculating surface gravity of the black holes. For the 3+1 dimensional black holes, the Hawking temperatures are related to the fundamental parameters of Horava-Lifshitz gravity.Comment: V2: references added, typo corrected, 16page

Rare Earth Eu Doped PtRu/C Catalysts and Their Properties for Methanol Electrooxidation

Commercially available PtRu/C catalyst was doped with Eu by chemical reduction and sintering, resulting in PtRuEux/C catalysts with different Eu contents. The catalysts were characterized by transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Results showed that Eu doping did not change the average size of the PtRu/C catalysts (ca 3 nm), and their surfaces were modified by both Eu metal and oxide. Cyclic voltammetry and chronoamperometry demonstrated that the activity of the PtRuEux/C catalysts was higher than that of commercial PtRu/C for methanol electrooxidation. Among the PtRuEux/C catalysts, PtRuEu0.3/C exhibited the best performance. The electrocatalytic oxidation of methanol on the catalyst was further investigated by in situ Fourier transform infrared (FTIR) spectroscopy at molecular level. Results indicated that the adsorbed species derived from the dissociative adsorption of methanol on the catalysts were linear. bonded CO (COL). Eu doping decreased the oxidation potential of COL and thus significantly enhanced the activity of the catalysts and their tolerance to CO.National Natural Science Foundation of China [20833005, 20828005]; Scientific Research Foundation, Ministry of Education ; Opening Foundation of the State Key Laboratory for Physical Chemistry of Solid Surface of Xiamen University ; Innovation Project of Guangxi Graduate Education, Chin

Indometacin loading and in vitro release properties from novel carbopol coated spherical mesoporous silica nanoparticles

Spherical MCM-41 silica nanosized particles were synthesized and post synthesis modified by 3-aminopropyltriethoxysilane (APTES) in order to prepare amino-functionalized carrier. Both types of silica particleswere loaded with indometacin and further coated with carbopol. The preservation of morphology and pore structure of the particles was observed by XRD, TEM and N2 physisorption. FT-IR spectroscopy revealed the interaction between carboxyl groups of indometacin and the amino groups of the functionalized MCM-41. Amino-functionalization of the carrier resulted in higher degree of indometacin loading in comparison to the parent MCM-41, 39% vs. 30%, respectively. The coating of drug loaded amino-MCM-41 silica particles with carbopol significantly reduced the initial burst release of indometacin. Both silica carriers demonstrated no cytotoxicity on HL-60 (acute myeloid leukemia) and K-562 (chronic myeloid leukemia) cell lines

Development and validation of an ELISA using a protein encoded by ORF2 antigenic domain of porcine circovirus type 2

<p>Abstract</p> <p>Background</p> <p>The capsid protein (ORF2) is a major structural protein of porcine circovirus type 2 (PCV2). A simple and reliable diagnostic method based on ORF2 protein immunoreactivity would serve as a valuable diagnostic method for detecting serum antibodies to PCV2 and monitoring PCV infection. Here, we reported an indirect enzyme-linked immunosorbent assay (I-ELISA) by using an antigenic domain (113-147AA) of ORF2-encoded antigen, expressed in <it>E. coli</it>, for diagnosis of PCV infection.</p> <p>Results</p> <p>The ELISA was performed on 288 serum samples collected from different porcine herds and compared with an indirect immunofluorescent assay (IFA). In total, 262 of 288 samples were positive as indicated by both I-ELISA and IFA. The specificity and sensitivity of I-ELISA were 87.7% and 93.57%.</p> <p>Conclusions</p> <p>This ELISA is suitable for detection and discrimination of PCV2 infection in both SPF and farm antisera.</p