A NOVEL SCHEME OF STRAIN-CONSTRUCTED POINT INTERPOLATION METHOD FOR STATIC AND DYNAMIC MECHANICS PROBLEMS

This paper presents a new scheme of strain-constructed point interpolation method (SC-PIM) for static, free and forced vibration analysis of solids and structures using triangular cells. In the present scheme, displacement fields are assumed using shape functions created via the point interpolation method (PIM), which possess the Kronecker delta property facilitating the straightforward enforcement of displacement boundary conditions. Using the generalized gradient smoothing technique, the "smoothed" strains at the middle points of the cells edges are first obtained using the corresponding edge-based smoothing domains and the assumed displacement field. In each triangular background cell, the strains at the vertices are assigned using these smoothed strains in a proper manner, and then piecewisely linear strain fields are constructed by the linear interpolation for each sub-triangular cell using the edge-based "smoothed" strains. With the assumed displacements and constructed linear strain fields, the discretized system equations are created using the Strain Constructed Galerkin (SC-Galerkin) weak form. A number of benchmark numerical examples, including the standard patch test, static, free and forced vibration problems, have been studied and intensive numerical results have demonstrated that the present method possesses the following properties: (1) it works well with the simplest triangular mesh, no additional degrees of freedom and parameters are introduced and very easy to implement; (2) it is at least linearly conforming; (3) it possesses a close-to-exact stiffness: it is much stiffer than the "overly-soft" node-based smoothed point interpolation method (NS-PIM) and much softer than the "overly-stiff" FEM model; (4) the results of the present method are of superconvergence and ultraaccuracy: about one order of magnitude more accurate than those of the linear FEM; (5) there are no spurious non-zeros energy modes found and it is also temporally stable, hence the present method works well for dynamic problems

Comparison of the Therapeutic Effects of Acupuncture at PC6 and ST36 for Chronic Myocardial Ischemia

We aimed to compare the differences of the effects on chronic myocardial ischemia (MI) of acupuncture at PC6 and ST36. The chronic MI model of minipigs was created by implanting an Ameroid constrictor on the left anterior descending coronary artery (LAD) and then two weeks’ acupuncture was stimulated at PC6 or ST36, respectively. The results showed that both acupoints’ stimulation decreased the serous cardiac troponin T (cTnT) and ischemia modified albumin (IMA) significantly and improved the ischemic ECG changes. The amplitude of pathological Q wave in the PC6 group decreased more significantly than that of the ST36 group. The cardiovascular magnetic resonance imaging (cMRI) results showed that the decreased left ventricular ejection fraction (LVEF) was not improved obviously in both groups. The left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV) enlarged progressively even after acupuncture. The left ventricular wall mass (LVWM) in the ST36 group increased more obviously than that of the PC6 group, which paralleled the decreasing angiotensin II (Ang II) concentration in the plasma. These results suggested that acupuncture at PC6 or ST36 was effective for protecting the myocardium from chronic ischemic injury, and the effect of PC6 seemed to be better

Study on the Conventional Performance and Microscopic Properties of PPA/SBS-Modified Bio-Mixed Asphalt

To promote the construction of environmentally friendly, sustainable pavements and solve the impact of the scarcity of asphalt resources on highway development, bio-mixed asphalt (BMA) modified by SBS and polyphosphoric acid (PPA) was prepared, and the influence of the ratio of bio-asphalt (BA) replacing petroleum asphalt on different PPA/SBS blending schemes was explored through conventional property tests. According to each PPA/SBS blending scheme, the optimal replacement ratio of bio-asphalt was optimized, and the microstructure and distribution morphology of different PPA/SBS-modified BMA were evaluated. Conventional property test results show that with the same PPA/SBS content, the replacement ratio of bio-asphalt has a significant impact on the conventional performance of composite-modified asphalt, but the appropriate replacement ratio of bio-asphalt can improve the storage stability and conventional performance of composite-modified asphalt; in micromorphological analysis, it was found that the number of bee-like structures on the surface of the modified BMA decreased significantly, which indicated that the molecular heterogeneity of various components in the asphalt was reduced. In addition, bio-asphalt changed the particle morphology and improved the dispersity of SBS in asphalt. The composite-modified BMA had a lower SBS content, but its conventional performance was still excellent—so it has significant application prospects in road engineering

LA-ICP-MS U–Pb Dating of Cenozoic Rutile Inclusions in the Yuanjiang Marble-Hosted Ruby Deposit, Ailao Shan Complex, Southwest China

Among the marble-hosted ruby deposits in the Himalayan tectonic belt, which yields the highest-quality rubies in the world, the Yuanjiang deposit is the only economically viable one located in China. More attempts are necessary to put constraints on the ore-forming age of these marble-hosted ruby deposits. Here, we dated rutile inclusions in the Yuanjiang rubies using the LA-ICP-MS U–Pb method, which yielded a lower intercept 206Pb/238U age of 20.2 ± 1.2 Ma on the Tera-Wasserburg plot, close to the 22.5–22.2 Ma 40Ar/39Ar ages of phlogopite from the ruby host matrix assemblage. Our U–Pb rutile age put a constraint on the cooling history of the Yuanjiang rubies deposit. The new rutile age is consistent with our previous model that shows the ca. 28–22 Ma left lateral shearing plays an important role in transporting the ruby deposit toward the surface. This study provides the first example of in-situ U–Pb dating of rutile in the Himalayan tectonic belt, demonstrating the great potential of U–Pb rutile geochronology for Cenozoic mineral deposits

A Particle Swarm Optimization Algorithm for Neighbor Selection in Peer-to-Peer Networks

Peer-to-peer (P2P) topology has significant influence on the performance, search efficiency and functionality, and scalability of the application. In this paper, we propose a Particle Swarm Optimization (PSO) approach to the problem of Neighbor Selection (NS) in P2P Networks. Each particle encodes the upper half of the peer-connection matrix through the undirected graph, which reduces the search space dimension. The results indicate that PSO usually required shorter time to obtain better results than Genetic Algorithm (GA), specially for large scale problems. 1

Effect of short-term aging on rheological properties of bio-asphalt/SBS/PPA composite modified asphalt

Substituting petroleum asphalt with bio-asphalt produced by biological waste recycling can mitigate the dependence on non-renewable resource oil. This study aimed to investigate the effectiveness of bio-asphalt as a substitute for petroleum asphalt by analyzing its rheological properties. Therefore, in this study, modified asphalt was prepared using styrene-butadiene-styrene copolymer (SBS), polyphosphoric acid (PPA), and bio-asphalt (BA) as modifiers, and the short-term aging test of the modified asphalt was carried out. Then the rheological properties of the modified asphalt were analyzed through the Temperature Scanning (TS) test, the Multiple Stress Creep Recovery (MSCR) test, and the Bending Beam Rheometer (BBR) test; finally, the Fourier Transform infrared spectroscopy (FTIR) test, Fluorescence Microscopy (FM) test to study the modification mechanism and microscopic characteristics of asphalt. The results show that adding BA improved the low-temperature rheological properties of modified asphalt while reducing the high-temperature rheological properties of PPA modified asphalt. The BA, SBS, and PPA combination exhibited excellent performance in high and low-temperature conditions. The short-term aging process enhances the high-temperature rutting resistance of modified asphalt but adversely affects its low-temperature performance. Fluorescence microscopy tests have demonstrated that BA improves the compatibility of SBS and PPA in asphalt. Meanwhile, FTIR has revealed that BA and SBS are physically mixed, and BA and PPA undergo a chemical reaction. This study suggests that BA could be a viable and sustainable alternative to petroleum asphalt, with promising performance characteristics when combined with SBS and PPA modifiers

Numerical Prediction of Ship Resistance Based on Volume of Fluid Implicit Multi-Step Method

The Volume of Fluid (VOF) method is used in two-phase fluid flow problems of ship hydrodynamic calculations, to capture the motion and distribution of the gas–liquid free surface. To ensure solution stability and accuracy, numerical simulations typically require separate mesh refinement for the free surface or a reduced time step, resulting in a significant increase in solution time. This study aims to compare the drag and vessel attitude change calculations of the VOF implicit multi-step method with the traditional single-step method, and to verify the feasibility of the method in the numerical prediction of ship resistance and flow field analysis. The results show that an implicit multi-step method with a reasonable number of internal iterations could obtain results close to those of the single-step method with a reduced time step, and the error in trim angle was relatively large, about 2%, but the solving time was only about half that of the latter. The method could also capture the shape and location of waves on the hull, especially in the vicinity of the ship, while the distribution of the waves in the far field differed from those in the experiments to some extent

Raman spectroscopy analysis of the biochemical characteristics of molecules associated with the malignant transformation of gastric mucosa.

OBJECTIVE: The purpose of this study was to comparatively analyze the signature Raman spectra of genomic DNA, nuclei, and tissue of normal gastric mucosa and gastric cancer and to investigate the biochemical transformation of molecules associated with gastric mucosa malignancy. METHOD: Genomic DNA, nuclei, and tissue from normal gastric mucosa and gastric cancer were analyzed by Raman spectroscopy. RESULTS: 1) The Raman spectrum of gastric cancer genomic DNA showed that two peaks appeared, one at approximately 1090 cm-1 with a higher intensity than the peak at 1050 cm-1 in the spectrum. Characteristic peaks appeared at 950 cm-1, 1010 cm-1, and 1100-1600 cm-1. 2) Using a hematoxylin and eosin (H&E)-stained section, the intensity of the characteristic peak of nucleic acids at 1085 cm-1 was increased and shifted to 1088 cm-1 in cancer cells. The relative intensity of the characteristic peaks of nucleoproteins at 755 cm-1 and 1607 cm-1 was significantly increased in cancer cells compared with normal cells. 3) Compared with normal tissues, the peak representing PO2- symmetric stretching vibration shifted from 1088 cm-1 to 1083 cm-1 in cancer tissue, and the characteristic peak for collagen at 938 cm-1 shifted to 944 cm-1. In addition, an extra characteristic peak indicating C = C stretching vibration appeared at 1379 cm-1 in the lipid spectrum in cancer tissue. CONCLUSIONS: The position, intensity, and shape of peaks in the Raman spectra of DNA, nuclei, and tissue from gastric cancer were significantly different compared with those of normal cells. These results indicate that the DNA phosphate backbone becomes unstable in cancer cells and might be broken; the relative content of histones is increased and stable; the relative collagen content is reduced, facilitating cancer cell metastasis; and the relative content of unsaturated fatty acids is increased, increasing the mobility of the plasma membrane of cancer cells