Improved SVR Method for Predicting the Cutting Force of a TBM Cutter Using Linear Cutting Machine Test Data

Mengmeng Hu,Biao Li,Bo Zhang,Ruirui Wang,Lei Chen 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.11

This research introduces a support vector regression (SVR) method to predict the cutting forces acting on the constant cross section (CCS) disc cutter, including the normal force (FN) and rolling force (FR), based on linear cutting machine (LCM) test data. To improve the prediction effect, an improved SVR-Outlier Detection (SVR-OD) method and an Additional Input Variable (AIV) method are proposed. After removing the outliers, 148 typical LCM test samples form the training set. Here, 70 samples from the Hangzhou No.2 Water Supply Channel constitute the test set. The prediction results show that the Root-mean-squared Relative Error (RMRE) values of the normal force and rolling force are 19.5% and 24.8%, respectively, and the corresponding determination coefficients are 0.845 and 0.807, respectively. For the prediction of the peak cutting force with an important reference to tunnel boring machine (TBM) design, the proportions of samples with an Absolute Relative Error (ARE) value of less than 20% for FN and FR are 9/10 and 7/7, respectively. The above prediction results are better than those of the common SVR method; thus, the developed method can effectively simulate the cutting force required by a rock mass with good integrity. The cutting force prediction using LCM test data is feasible and practical. In addition, the comparison of the prediction results between the improved SVR and common SVR methods shows that the improved SVR-OD and AIV methods play an active role in improving the prediction accuracy of the SVR method.

Graphene oxide nanosheets to improve permeability and selectivity of PIM-1 membrane for carbon dioxide separation

Mengmeng Chen,Faizal Soyekwo,Qiugen Zhang,Chuan Hu,Aimei Zhu,Qinglin Liu 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.63 No.-

Polymers of intrinsic microporosity (PIMs) have attracted increasing interest in gas separation membranes due to their high permeability. However, the moderate selectivity limits their wide applications in CO2 separation. Herein we report a facile strategy to improve simultaneously the permeability and CO2 selectivity of PIMs membrane using the prepared PIM-1/graphene oxide (GO) nanosheets mixed matrix membrane. The GO nanosheets improves the hydrophilicity and surface roughness of PIM-1 membrane whereas the uniform assembly of GO nanosheets in the PIM-1 matrix creates the hydrophilic/hydrophobic microphase segregation in the membrane. The as-prepared mixed matrix membrane is also very porous and has a pore size of about 0.78 nm. The combination of these properties significantly contributes to the enhancement of the gas separation performance of PIM-1 membrane, with the resultant membrane exhibiting an exceptionally high CO2 permeability of up to 6169 barrer as well as a high CO2/N2 selectivity of 123.5, which is more than 7 times that of the pure PIM-1 membrane. The developed PIM-1/GO mixed matrix membrane should have a wide application in the CO2 separation.

Alterations in antioxidant function and cell apoptosis in duck spleen exposed to molybdenum and/or cadmium

Mengmeng Zhang,Junrong Luo,Caiying Zhang,Huabin Cao,Bing Xia,Guoliang Hu 대한수의학회 2017 Journal of Veterinary Science Vol.18 No.2

To investigate the effects of molybdenum (Mo) and/or cadmium (Cd) on antioxidant function and the apoptosis-related genes in duck spleens. Sixty healthy 11-day-old ducks were randomly divided into six groups of 10 ducks (control, low Mo group, high Mo, Cd, low Mo + Cd, and high Mo + Cd groups). All were fed a basal diet containing low or high dietary doses of Mo and/or Cd. Relative spleen weight, antioxidant indices, apoptosis-related gene mRNA expression levels, and ultrastructural changes were evaluated after 120 days. The results showed that the relative spleen weight decreased significantly in the high Mo + Cd treatment group which compared with control group. Malondialdehyde levels increased and xanthine oxidase and catalase activities decreased in the Mo and/or Cd groups compared with levels in the control group. Bak-1 and Caspase-3 expressions were upregulated in the high Mo + Cd group, while Bcl-2 was downregulated. In addition, mitochondrial crest fracture, swelling, vacuolation, deformed nuclei, and karyopyknosis in both Mo + Cd treated groups were more severe than in the other groups. The results suggest that Mo and/or Cd can induce oxidative stress and apoptosis of spleen via effects on the mitochondrial intrinsic pathway. Moreover, the results indicate the two elements have a possible synergistic relationship.

miR-30c regulates proliferation, apoptosis and differentiation via the Shh signaling pathway in P19 cells

Xuehua Liu,Mengmeng Li,Yuzhu Peng,Xiaoshan Hu,Jing Xu,Shasha Zhu,Zhangbin Yu,Shuping Han 생화학분자생물학회 2016 Experimental and molecular medicine Vol.48 No.-

MicroRNAs (miRNAs) are small, non-coding single-stranded RNAs that suppress protein expression by binding to the 3′ untranslated regions of their target genes. Many studies have shown that miRNAs have important roles in congenital heart diseases (CHDs) by regulating gene expression and signaling pathways. We previously found that miR-30c was highly expressed in the heart tissues of aborted embryos with ventricular septal defects. Therefore, this study aimed to explore the effects of miR-30c in CHDs. miR-30c was overexpressed or knocked down in P19 cells, a myocardial cell model that is widely used to study cardiogenesis. We found that miR-30c overexpression not only increased cell proliferation by promoting cell entry into S phase but also suppressed cell apoptosis. In addition, we found that miR-30c inhibited dimethyl sulfoxide-induced differentiation of P19 cells. miR-30c knockdown, in contrast, inhibited cell proliferation and increased apoptosis and differentiation. The Sonic hedgehog (Shh) signaling pathway is essential for normal embryonic development. Western blotting and luciferase assays revealed that Gli2, a transcriptional factor that has essential roles in the Shh signaling pathway, was a potential target gene of miR-30c. Ptch1, another important player in the Shh signaling pathway and a transcriptional target of Gli2, was downregulated by miR-30c overexpression and upregulated by miR-30c knockdown. Collectively, our study revealed that miR-30c suppressed P19 cell differentiation by inhibiting the Shh signaling pathway and altered the balance between cell proliferation and apoptosis, which may result in embryonic cardiac malfunctions.

Peer Effect in Spreading Network of Fake Information in Public Crisis

Xiaoxia Zhu,Mengmeng Liu,Haiju Hu 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.12

Sustained electron tunneling at unbiased metal-insulator-semiconductor triboelectric contacts

Liu, Jun,Miao, Mengmeng,Jiang, Keren,Khan, Faheem,Goswami, Ankur,McGee, Ryan,Li, Zhi,Nguyen, Lan,Hu, Zhiyu,Lee, Jungchul,Cadien, Ken,Thundat, Thomas Elsevier 2018 Nano energy Vol.48 No.-

<P><B>Abstract</B></P> <P>Generating sufficient current density for powering electronic devices remains as one of the critical challenges of mechanical energy harvesting techniques based on piezo and triboelectricity, mainly due to the high impedance of the insulating material systems. Here we report on producing sustainable tunneling current using an unbiased, triboelectrically charged metal-insulator-semiconductor (MIS) point contact system, consisting of p-type silicon, silicon oxide and a metal tip. The native thin oxide (~ 1.6 nm) on the silicon surface provides a natural pathway for quantum mechanical tunneling of the triboelectrically generated electrons into the silicon substrate. Lateral back and forth sliding motion of the tip, irrespective of the direction of motion, generates a constant direct current (d.c.) with very high current density. The measured current shows an exponential decay with the thickness of oxide layer deposited with atomic layer deposition (ALD), confirming the quantum mechanical tunneling mechanism. It is proposed that the contact potential difference enhanced by triboelectric charging provides potential difference between metal point contact and the substrate. With single metallic micro probe sliding on a moderately doped p-type silicon, an open circuit voltage (<I>V</I> <SUB>oc</SUB>) of 300–400 mV and a short-circuit direct current (<I>I</I> <SUB>sc</SUB>) of 3–5 μA (a corresponding high current density, <I>J</I>, in the order of 1–10 A/m<SUP>2</SUP>) have been observed. It is predicted from conductive-atomic force microscopy (C-AFM) experiment that the theoretical <I>J</I> can be as high as 10<SUP>4</SUP> A/m<SUP>2</SUP>. This new concept has the potential as a green energy harvesting technique where a broad range of material candidates and device configurations could be used.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Quantum mechanical tunneling at triboelectrically charged interface through ultrathin oxide layer is demonstrated. </LI> <LI> Tribo-tunneling is found to be a universal phenomenon in MIS frictional contact system. </LI> <LI> High current density <I>J</I> of 5 A/m<SUP>2</SUP> is experimentally measured in doped silicon materials at macroscale. </LI> <LI> Ultrahigh C-AFM <I>J</I> of 10<SUP>4</SUP> A/m<SUP>2</SUP> is observed due to the nano-size probe-induced high electric field. </LI> <LI> This method can be used as cost-effective triboelectric DC current generator, due to easily available silicon wafers with native oxide. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Acid–base bifunctional catalysis by a heteropolyacid and amines on the polyetheretherketone fiber for cleaner acceleration of the one-pot tandem reactions

Lijuan Jiang,Xian-Lei Shi,Yue Lv,Honghui Gong,Shuangshuang Liu,Mengmeng Du,Qianqian Hu,Keren Shi 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.113 No.-

The development of highly efficient, economical and environmentally friendly catalytic systems is ofgreat significance from the green chemistry point of view. In this paper, we presented a succinct approachto create a heterogeneous acid–base bifunctional catalyst for one-pot tandem reaction from the commerciallyavailable textile fiber. The ultra-high strength textile fiber polyetheretherketone (PEEK) was functionalizedby a post-grafting method to combine two antagonistic active functions in a synergisticcatalyst, and the resulting fiber samples were characterized in detail by morphology, mechanical properties,elemental analysis, X-ray photoelectron spectroscopy, inductively coupled plasma-atomic emissionspectrometry, X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet–visible spectrum,nuclear magnetic resonance spectroscopy and thermogravimetric analysis, and further revealed thatthe amines and the heteropolyacid were immobilized by acid–base interactions in the PEEK surface layerwith sufficient stability. Moreover, the acid–base bifunctional catalyst can be successfully applied in theacceleration of the one-pot tandem deacetalization–Knoevenagel reactions with high-efficiency (lowercatalyst dosage 0.3 mol%, higher product yields 81–92%), whereas the homogeneous catalysts wereunable to initiate the reaction due to their mutual neutralization in solution, and the catalytic mechanismwas elucidated by comparison. Furthermore, the fibrous catalyst could maintain its activities more than10 cycles with a simple post-processing, and the mediated system was capable of enlarging to the gramscale,which are envisaged for industrial operations and cleaner productions.