Iso-level tool path planning for free-form surfaces

The aim of tool path planning is to maximize the efficiency against some given precision criteria. In practice, scallop height should be kept constant to avoid unnecessary cutting, while the tool path should be smooth enough to maintain a high feed rate. However, iso-scallop and smoothness often conflict with each other. Existing methods smooth iso-scallop paths one-by-one, which make the final tool path far from being globally optimal. This paper proposes a new framework for tool path optimization. It views a family of iso-level curves of a scalar function defined over the surface as tool path so that desired tool path can be generated by finding the function that minimizes certain energy functional and different objectives can be considered simultaneously. We use the framework to plan globally optimal tool path with respect to iso-scallop and smoothness. The energy functionals for planning iso-scallop, smoothness, and optimal tool path are respectively derived, and the path topology is studied too. Experimental results are given to show effectiveness of the proposed methods

Tool path planning based on conformal parameterization for meshes

AbstractThe similarity property of conformal parameterization makes it able to locally preserve the shapes between a surface and its parameter domain, as opposed to common parameterization methods. A parametric tool path planning method is proposed in this paper through such parameterization of triangular meshes which is furthermore based on the geodesic on meshes. The parameterization has the properties of local similarity and free boundary which are exploited to simplify the formulas for computing path parameters, which play a fundamentally important role in tool path planning, and keep the path boundary-conformed and smooth. Experimental results are given to illustrate the effectiveness of the proposed methods, as well as the error analysis

Research of piezoelectric acoustic liner

The piezoelectric acoustic liner is a new type of acoustic liner that uses piezoelectric patches to replace the traditional mechanical structure. Its working principle is to change the resonator volume of acoustic liner by inverse piezoelectric effect. In this paper, the finite element method is used to analyze the deformation of piezoelectric patches and the acoustic performance of piezoelectric acoustic liner, when the piezoelectric patch deformation is 0.1 mm, the noise elimination frequency band offset of the acoustic liner is about 30 Hz, and related experiments are designed. The experimental results confirm that noise elimination frequency range of piezoelectric acoustic liner is 1100 Hz to 1300 Hz within the voltage range of 0 V to 200 V

Adenovirus-mediated sphingomyelin synthase 2 increases atherosclerotic lesions in ApoE KO mice

<p>Abstract</p> <p>Background</p> <p>Sphingomyelin synthase 2 (SMS2) contributes to de novo sphingomyelin (SM) biosynthesis. Its activity is related to SM levels in the plasma and the cell membrane. In this study, we investigated the possibility of a direct relationship between SMS and atherosclerosis.</p> <p>Methods</p> <p>The Adenovirus containing SMS2 gene was given into 10-week ApoE KO C57BL/6J mice by femoral intravenous injection. In the control group, the Adenovirus containing GFP was given. To confirm this model, we took both mRNA level examination (RT-PCR) and protein level examination (SMS activity assay).</p> <p>Result</p> <p>We generated recombinant adenovirus vectors containing either human SMS2 cDNA (AdV-SMS2) or GFP cDNA (AdV-GFP). On day six after intravenous infusion of 2 × 10¹¹particle numbers into ten-week-old apoE KO mice, AdV-SMS2 treatment significantly increased liver SMS2 mRNA levels and SMS activity (by 2.7-fold, 2.3-fold, p < 0.001, respectively), compared to AdV-GFP treated mice. Moreover, plasma total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), and sphingomyelin (SM) levels were significantly increased by 39% (p < 0.05), 42% (p < 0.05), 68% (p < 0.001), and 45% (p < 0.05), respectively. Plasma high-density lipoprotein cholesterol (HDL-C), phosphatidylcholine (PC), and PC/SM ratio were decreased by 42% (p < 0.05), 18% (p < 0.05), and 45% (p < 0.05), respectively. On day 30, the atherosclerotic lesions on the aortic arch of AdV-SMS2 treated mice were increased, and the lesion areas on the whole aorta and in the aortic root were significantly increased (p < 0.001). Furthermore, the collagen content in the aorta root was significantly decreased (p < 0.01).</p> <p>Conclusions</p> <p>Our results present direct morphological evidence for the pro-atherogenic capabilities of SMS2. SMS2 could be a potential target for treating atherosclerosis.</p

Degradation of Toxic Organic Contaminants by Graphene Cathode in an Electro‐Fenton System

A novel composite electrode was constructed by pressing graphene and CuO, using a cathode in an electro‐Fenton (EF) system. Cyclic voltammetry, charge/discharge curve and electrochemical impedance spectroscopy (EIS) were used to characterize the composite electrode. The degradation of a toxic organic contaminant, Terramycin, by EF system was studied in an undivided electrolysis cell. The possible degradation products of Terramycin were studied by a Fourier transform‐infrared spectrum, and the findings showed that the structure of Terramycin was damaged. The variations of hydrogen peroxide and the relative content of hydroxyl radical (.OH) during the degradation process were traced by enzyme catalysis method and fluorescence spectrometry. The results showed that the electro‐catalytic degradation of Terramycin occurred by an ·OH radical mechanism. More importantly, this as‐prepared cathode was very stable and could be reused without any catalytic activity decrease, suggesting its potential application in the wastewater treatment

Severe Maternal Hyperglycemia Exacerbates the Development of Insulin Resistance and Fatty Liver in the Offspring on High Fat Diet

Background. Adverse maternal environments may predispose the offspring to metabolic syndrome in adulthoods, but the underlying mechanism has not been fully understood. Methods. Maternal hyperglycemia was induced by streptozotocin (STZ) injection while control (CON) rats received citrate buffer. Litters were adjusted to eight pups per dam and then weaned to standard diet. Since 13 weeks old, a subset of offspring from STZ and CON dams were switched to high fat diet (HFD) for another 13 weeks. Glucose and insulin tolerance tests (GTT and ITT) and insulin secretion assay were performed; serum levels of lipids and leptin were measured. Hepatic fat accumulation and islet area were evaluated through haematoxylin and eosin staining. Results. STZ offspring exhibited lower survival rate, lower birth weights, and growth inhibition which persisted throughout the study. STZ offspring on HFD showed more severe impairment in GTT and ITT, and more profound hepatic steatosis and more severe hyperlipidemia compared with CON-HFD rats. Conclusions. Offspring from diabetic dams would be prone to exhibit low birth weight and postnatal growth inhibition, but could maintain normal glucose tolerance and insulin sensitivity. HFD accelerates development of insulin resistance in the offspring of diabetic dams mainly via a compensatory response of islets