Three-Dimensional CFD Simulations of Start-Up Processes of a Pump-Turbine Considering Governor Regulation

The pumped-storage power station is an efficient stability regulator of the power grid. However, due to the instability of the pump-turbine in the S-shaped characteristic region, rotational speed fluctuation is easy to occur in the speed no-load condition, making synchronization with and connection to the grid difficult. To investigate the key factors of these difficult grid connections, the start-up processes of a practical pump-turbine under the lowest head condition were simulated by using the three-dimensional CFD method, in which the governor regulating equations with different regulating parameters were integrated successfully. The results show that the working points oscillate with the fluctuations of rotational speed, discharge, and torque, and different regulating parameters have a significant influence on the dynamic histories. In addition, the internal flow patterns, especially the backflows at the runner inlet, keep apparent values at the middle span (0.5 span) but have regular transitions near the shroud side (0.7–0.8 span). The faster the guide vanes adjust, the faster the backflows change, and the larger the macro parameters fluctuate. Overall, the instability of the start-up is the result of the periodical evolutions of backflows at the runner inlet, because the trend and period of the radial velocities at different inlet span locations are consistent with those of the discharge.

Simplification algorithm of denture point cloud based on feature preserving

Due to the point cloud of oral scan denture has a large amount of data and redundant points. A point cloud simplification algorithm based on feature preserving is proposed to solve the problem that the feature preserving is incomplete when processing point cloud data and cavities occur in relatively flat regions. Firstly, the algorithm uses kd-tree to construct the point cloud spatial topological to search the k-Neighborhood of the sampling point. On the basis of that to calculate the curvature of each point, the angle between the normal vector, the distance from the point to the neighborhood centroid, as well as the standard deviation and the average distance from the point to the neighborhood on this basis, therefore, the detailed features of point cloud can be extracted by multi-feature extraction and threshold determination. For the non-characteristic region, the non-characteristic point cloud is spatially divided through Octree to obtain the K-value of K-means clustering algorithm and the initial clustering center point. The simplified results of non-characteristic regions are obtained after further subdivision. Finally, the extracted detail features and the reduced result of non-featured region will be merged to obtain the final simplification result. The experimental results show that the algorithm can retain the characteristic information of point cloud model better, and effectively avoid the phenomenon of holes in the simplification process. The simplified results have better smoothness, simplicity and precision, and are of high practical value.

Experimental and Computational analysis of springback in dual phase steels

In this work the comfortability of dual-phase automotive steel DP600 is studied through uniaxial tensile tests and V-die bending tests in different directions relative to the rolling direction. A microstructural analysis was also carried out in each characteristic region of the deformation zone, evidencing the changes in the morphology of the microstructure grains. Additionally, the plastic anisotropy of the material was studied by implementing the constitutive anisotropy models known as Hill-48 and Barlat-89. The results showed an increase in elastic recovery at 45 ° and 90 ° from the rolling direction. This variation can be attributed to the morphology of the martensite that created preferential location zones within the material during the rolling process. The two models Hill-48 and Barlat-89 correctly describe the yield surface and the plastic anisotropy obtained in the experimental tests carried out. The simulation using the finite element method and the Hill-48 model gave satisfactory results in the prediction of the elastic recovery as compared to the experimental results obtained with the V-die bending test.

Evaluation of aromatic amino acids as potential biomarkers in breast cancer by Raman spectroscopy analysis

The scope of the work undertaken in this paper was to explore the feasibility and reliability of using the Raman signature of aromatic amino acids as a marker in the detection of the presence of breast cancer and perhaps, even the prediction of cancer development in very early stages of cancer onset. To be able to assess this hypothesis, we collected most recent and relevant literature in which Raman spectroscopy was used as an analytical tool in the evaluation of breast cell lines and breast tissue, re-analyzed all the Raman spectra, and extracted all spectral bands from each spectrum that were indicative of aromatic amino acids. The criteria for the consideration of the various papers for this study, and hence, the inclusion of the data that they contained were two-fold: (1) The papers had to focus on the characterization of breast tissue with Raman spectroscopy, and (2) the spectra provided within these papers included the spectral range of 500–1200 cm−1, which constitutes the characteristic region for aromatic amino acid vibrational modes. After all the papers that satisfied these criteria were collected, the relevant spectra from each paper were extracted, processed, normalized. All data were then plotted without bias in order to decide whether there is a pattern that can shed light on a possible diagnostic classification. Remarkably, we have been able to demonstrate that cancerous breast tissues and cells decidedly exhibit overexpression of aromatic amino acids and that the difference between the extent of their presence in cancerous cells and healthy cells is overwhelming. On the basis of this analysis, we conclude that it is possible to use the signature Raman bands of aromatic amino acids as a biomarker for the detection, evaluation and diagnosis of breast cancer.

Examination of Chaotic Structures in Semiconductor or Alloy Voltage Time-Series: A Complex Network Approach for the Case of TlInTe2

This paper proposes a method for examining chaotic structures in semiconductor or alloy voltage oscillation time-series, and focuses on the case of the TlInTe2 semiconductor. The available voltage time-series are characterized by instabilities in negative differential resistance in the current–voltage characteristic region, and are primarily chaotic in nature. The analysis uses a complex network analysis of the time-series and applies the visibility graph algorithm to transform the available time-series into a graph so that the topological properties of the graph can be studied instead of the source time-series. The results reveal a hybrid lattice-like configuration and a major hierarchical structure corresponding to scale-free characteristics in the topology of the visibility graph, which is in accordance with the default hybrid chaotic and semi-periodic structure of the time-series. A novel conceptualization of community detection based on modularity optimization is applied to the available time-series and reveals two major communities that are able to be related to the pair-wise attractor of the voltage oscillations’ phase portrait of the TlInTe2 time-series. Additionally, the network analysis reveals which network measures are more able to preserve the chaotic properties of the source time-series. This analysis reveals metric information that is able to supplement the qualitative phase-space information. Overall, this paper proposes a complex network analysis of the time-series as a method for dealing with the complexity of semiconductor and alloy physics.

Three-Dimensional Reconstruction of Fleece Fabric Surface for Thickness Evaluation

Aiming at solving the problem of manually measuring the fabric surface thickness, this paper proposes a three-dimensional (3D) reconstruction method based on the tangential two-dimensional (2D) sequence images. Firstly, the characteristic region of the fabric surface is extracted. Secondly, the image is splitting based on the maximum between-class variance method. Thirdly, the splitting image is processed by the morphological method. Fourthly, the canny operator is used to obtain the edge detection for calculating the edge contour coordinate. Finally, the surf function is used to reconstruct the 3D model of the fabric surface. To evaluate the performance of the proposed 3D model, the thickness and relief degree of the fabric surface are used, and the comparison between the proposed method and the manual measurement is carried out. The results demonstrate that, under a reasonable relief degree condition, the proposed method is more effective to evaluate the thickness of the fabric surface and the estimated thickness is more accurate than the manually measured one.

Muhammad Arif Jati Purnomo TANAH SEBAGAI BAHAN PEWARNA PURBA YANG RAMAH LINGKUNGAN

Traces of “ ancient colors “ have begun to be known to humans since humans still live in caves. Some artifactsfrom the past are still displayed beautifully in several caves scattered throughout the world with conditions thatare still very good. This means that the colors depicted on the cave walls are still very clearly visible in thedirection of the colors such as red, white, black and brown. They have used natural coloring agents derivedfrom biotic and abiotic natural resources, such as animals, plants and mineral rocks Ancient colors becamean inspiration idea for researchers to conduct more in-depth research on materials and techniques by utilizingrocks or minerals that are around us. Stone, soil, bones, mixed with animal oil or fat can become coloringagents that have their own characteristics. It is possible to develop the potential of ancient colors that exist(plants, animals, soil, water, and rocks / minerals) in the batik center area of Sragen Regency to be exploredinto batik works of a characteristic region. The purpose of this Artistic (Art creation) research is to create anatural coloring formula from ancient rocks as an environmentally friendly natural dye for batik and its applicationto batik cloth.

Modeling of threshold effects in social systems based on nonlinear dynamics

This study proposes a model of threshold effects in social processes under conflict conditions. A model based on the diffusion equation of Langevin is developed. A solution of the system of equations for a divergent diffusion type is given. Using the example of two interactingconflicting groups of individuals, we have identified the characteristic patterns of social conflict in the social system in terms of threshold effects and determined the effect the social distance in society has in development of similar processes with regard to the external influence, dissipation, and random factors. We have demonstrated how the phase portrait of the system qualitatively changes as the parameters of the control function of the social conflict change in terms of threshold effects. Using the analysis data of the resulting phase portraits, we have concluded about the existence of a characteristic region of sustainability determined by the transition processes in terms of the threshold effect in the social system, within which it is relatively stable.

Methods of the matrix analysis and graphic ranking of the array of the experimental IR spectroscopy data in studying the inter-component processes in the mixture of pheniramine maleate and naproxen

A widespread use of complex pharmacotherapy entails the necessity of studying the processes occurred in pharmaceutical mixtures. IR spectroscopy is one of the methods used to assess the stability of substances. To increase the efficiency of interpretation of the IR spectra of mixtures, a method combining matrix methods and graphic ranking of the array of experimental data has been developed. This approach has been tested for the analysis of model mixtures of pharmaceutical substances naproxen and pheniramine maleate. Absorption spectra were obtained on an Avatar 360 FT-IR ESP Fourier transform spectrometer (Nicolet, USA) using an ATR (primary attenuation total reflection) attachment Smart Perfbmer (optical crystal ZnSe; spectral range 1.35 - 26.6 pm, 7400 - 375 cm4). The obtained IR spectra were processed using Thermo Scientific Specta embedded software. Graphs for graphical ranking were plotted in the coordinates of the mixture heating temperature —relative frequency intensity. The points on the graph represent the relative intensity of the bands for a mixture kept at a certain temperature, whereas the curves with which they are connected reflect the processes occurring in the structure of the substance. Common trends in the relative intensity for different frequencies (at the same temperature) and/or for a number of frequencies of a certain characteristic region, indicates the unidirectionality of the process. Graphic ranking is applied to the characteristic bands of pyridine and aliphatic nitrogen of pheniramine maleate and characteristic frequencies of the intermolecular hydrogen bond and carbonyl group of naproxen. We also used the method of mathematical ranking of the matrices of transmittance values. For the characteristic bands of the studied compounds, a combined use of graphical and mathematical ranking allowed us to infer a change in the structure of naproxen and pheniramine maleate under the impact of elevated temperatures: the salt of pheniramine and maleic acid in aliphatic nitrogen has one structural conformation, whereas the binding force depends on the temperature.