Analysis of the geometrical dependence of auxetic behavior in reentrant structures by finite elements

Materials with a negative Poisson＇s ratio（PR）are called auxetics;they are characterized by expansion/contraction when tensioned/compressed.Given this counterintuitive behavior,they present very particular characteristics and mechanical behavior.Geometrical models have been developed to justify and artificiall reproduce such materials＇ auxetic behavior.The focus of this study is the exploration of a reentrant model by analyzing the variation in the PR of reentrant structures as a function of geometrical and base material parameters.It is shown that,even in the presence of protruding ribs,there may not be auxetic behavior,and this depends on the geometry of each reentrant structure.Values determined for these parameters can be helpful as approximate reference data in the design and fabrication of auxetic lattices using reentrant geometries.

A simplified two-dimensional boundary element method with arbitrary uniform mean flow

To reduce computational costs, an improved form of the frequency domain boundary element method（BEM） is proposed for two-dimensional radiation and propagation acoustic problems in a subsonic uniform flow with arbitrary orientation. The boundary integral equation（BIE） representation solves the two-dimensional convected Helmholtz equation（CHE） and its fundamental solution, which must satisfy a new Sommerfeld radiation condition（SRC） in the physical space. In order to facilitate conventional formulations, the variables of the advanced form are expressed only in terms of the acoustic pressure as well as its normal and tangential derivatives, and their multiplication operators are based on the convected Green＇s kernel and its modified derivative. The proposed approach significantly reduces the CPU times of classical computational codes for modeling acoustic domains with arbitrary mean flow. It is validated by a comparison with the analytical solutions for the sound radiation problems of monopole,dipole and quadrupole sources in the presence of a subsonic uniform flow with arbitrary orientation.

Non Degeneration of Fibonacci Series, Pascal’s Elements and Hex Series

Generally Fibonacci series and Lucas series are the same, they converge to golden ratio. After I read Fibonacci series, I thought, is there or are there any series which converges to golden ratio. Because of that I explored the inter relations of Fibonacci series when I was intent on Fibonacci series in my difference parallelogram. In which, I found there is no degeneration on Fibonacci series. In my thought, Pascal triangle seemed like a lower triangular matrix, so I tried to find the inverse for that. In inverse form, there is no change against original form of Pascal elements matrix. One day I played with ring magnets, which forms hexagonal shapes. Number of rings which forms Hexagonal shape gives Hex series. In this paper, I give the general formula for generating various types of Fibonacci series and its non-degeneration, how Pascal elements maintain its identities and which shapes formed by hex numbers by difference and matrices.

Development of China's Public Health as an Essential Element of Human Rights

September 2017 Contents Preface Ensuring People’s Right to Health Based on China’s Conditions Continuous Improvement of Health Environment and Conditions Public Health Service Capability Improving Steadily Great Improvement in the Quality of Medical and Health Services Improvement of the National Medical Security System

Breakthrough in the China's Separation Technology for Extraction of Rare Earth Elements

Separation technology of rare earth elements （REEs）, as the critical step in the separation process, had long been fraught with technical difficulty. A research project conducted by Baotou Shibo Rare Earth Extraction ＆ Equipment Co. Ltd., Baotou REE Research Institute, and Baotou Steel ＆ REE Group Hi-Tech Co. Ltd （Inner Mongolia）, has successfully solved the problem using a centrifugal extractor and advanced techniques to achieve a key breakthrough.

Variations in wood tratis in micro and macro propagated plantation woods of Populus deltoides Bartr. ex Marsh

The paper presents a comparison between intra-ramet, intra-clonal and inter-clonal variations in girth at breast height (gbh), fiber length, fiber diameter, wall thickness, vessel element length, vessel element diameter and specific gravity in the ramets of L34, G3 and S7C15 clones of Populus deltoides at the age of 6 years old produced from planting material grown by macro- and micro-propagation techniques. Variance ratio (F) test indicated that intra-ramet variations were non-significant for all the characters except specific gravity for height in L34 for macro and specific gravity and vessel element diameter for radial locations for micro, and fiber length for G3 (micro) for height, and specific gravity for radial location and fiber length for height for S7C15 clone for both the techniques. The clone L34 showed the significantly higher girth followed by G3 and S7C15. The variations were significant for girth, vessel element length and specific gravity between the wood produced from planting stocks grown by two techniques. Intra-clonal variations were significant for fiber length, fiber diameter and vessel element length. In general wood element’s dimensions and specific gravity increased from bottom to top and pith to periphery radial locations. G3 clone was different from the L34 and S7C15 clone for the wood traits. The three different clones of Populus deltoides showed variability in wood anatomical properties and specific gravity in the woods grown from macro- and micro-propagated planting stock. So, the plantation raised by two techniques could not produce similar type of wood even from the same clone. G3 clone was the exception as it did not show variation in wood traits for two techniques. Intra-clonal variations in all the three clones of P. deltoides indicated that wood traits were not stable within the population of same clone grown by either method.

Can Persistent Children Hyperglycemia Be Induced by Causes Other Than Pancreas Failure?

In this work, children’s persistent hyperglycemia has been revised using the available literature to support the proposed reasoning. Based on this study, we have shown that the human glycemic management system must be seen as coupled and integrated by four subsystems, namely, production system, consumption system, distribution system, control system, and also it should be seen as coupled to external noxious factors/stressors, if not we show that the glycemic homeostasis analysis might be defective and might induce, in many cases, a misdiagnosis of the causes of the persistent hyperglycemia under consideration. Also, in this work, some considerations were presented to show that anomalies in the cerebral glycemic control through the glucose sensor neurons might be a possible cause/origin of some of the glycemic abnormalities and dysfunctions (however, not only the known related hypoglycemia but also hyperglycemia) that occur in childhood. Finally, it is shown that persistent novel external noxious factors of modernity or noxious factors already known, but amplified by modernity, such as persistent stress, media induced fears, and phobias, environmental pollution, and electromagnetic pollution, can and should also be considered as possible precursors for the development of anomalies in the juvenile homeostatic glycemic system that might well be, if intense and persistent, the driver of the worldwide observed T1DM epidemic events.

Algorithm for the layout of a piezoelectric element in an elastic medium providing the maximal piezoelectric effect within a specified frequency range

An algorithm for the layout of a piezoelectric that provides the most efficient performance within a specified range of vibration frequencies is proposed in this paper.This algorithm is based on the consideration of a special parameter within the area of a piezoelectric element’s possible location.This parameter characterizes the superposition of electromechanical coupling coefficients’for all the natural vibration frequencies included in a specified frequency range.The condition for defining the best option for location of the piezoelectric element in the case of several equivalent positions is specified.The efficiency of the proposed algorithm is shown numerically.The electromechanical coupling coefficients were calculated numerically based on solution to the problem of natural vibrations for electroelastic bodies using a finite element method.The calculations were performed to define the best location for a single piezoelectric element at the surface of a thin-walled shell having a half-cylindrical shape.The results are presented for natural vibration frequencies within the frequency range from 0 up to 1100 Hz.The numerical results were obtained by solving the problem of natural vibrations with a finite element method using the ANSYS software package.