Reference Element Research Articles

Symbolic Evaluation of hp‐FEM Element Matrices

AbstractIn this paper we consider higher order shape functions for finite elements on a triangle. On the reference element Dubiner‐like ansatz functions based on suitable integrated Jacobi polynomials are chosen. It can be proved that the corresponding mass and stiffness matrices are sparse for all polynomial degree p. Due to the orthogonal relations between Jacobi polynomials the exact values of the entries of mass and stiffness matrix can be determined. Using symbolic computation, we can find simple recurrence relations which allow us to compute the remaining nonzero entries in optimal arithmetic complexity.

Zirconium as a suitable reference element for estimating potentially toxic element enrichment in treated wastewater discharge vicinity.

The suitability of a reference element or normalizer used in assessing soil contamination levels using enrichment factor (EF) is important for soil quality assessment and monitoring. This study evaluated the results of using three reference elements Ti, Fe, and Zr for EF determination of Rb and Sr in soils within treated wastewater discharge vicinity, Central Botswana. The upper continental crust (UCC), world average values (WAV), and the local background values (LBV) were used in EF assessment of eight pedons. The elemental concentrations of the soils were determined with portable X-ray fluorescence (pXRF) analyzer. Relationships between the elements were strongly significant between Rb and Ti (r = 0.600, p < 0.01), Rb and Fe (r = 0.735, p < 0.01), Sr and Ti (r = 0.545, p < 0.01), and Sr and Fe (r = 0.841, p < 0.01). Second-level correlation analysis between contamination factor (CF) and EF levels showed Zr as the best reference element for Rb and Sr in the soils. Results from this study provide baseline knowledge necessary for contamination assessment and monitoring of soils with similar environmental conditions.

Mediação no ensino médio público: uma abordagem interdisciplinar entre o direito à educação e a antropologia jurídica, a partir do pensamento de Étienne Le Roy

Nesta pesquisa interdisciplinar entre o direito à Educação, em seu âmbito constitucional, e a Antropologia Jurídica, a partir da Teoria do Multijuridismo proposta por Étienne Le Roy, buscou-se sustentar a hipótese de que em relações sociais continuadas, a mediação ocorre mais nos limites dos modelos de conduta e comportamento e sistemas de disposições duráveis do que da regulação estatal. O artigo desenvolve-se por meio da análise comparativa entre dispositivos legais de interesse do ensino médio público e os principais elementos do referencial teórico, em especial a noção de juridicidade e a mediação. Os resultados obtidos, ainda que parciais, indicam que a comprovação da hipótese inicial demanda maior aprofundamento teórico e pesquisa de campo. Contudo, os mesmos resultados indicam o grande potencial de contribuição da obra de Étienne Le Roy para o desvelamento de novas formas de abordagem e concreção da regulação estatal da Educação do Brasil.

Multiple self-cleaning paper-based electrochemical ratiometric biosensor based on the inner reference probe and exonuclease III-assisted signal amplification strategy

Rapid and accurate detection of nucleic acids plays a major role in biological research and clinical diagnostics. Here, a 3D multiple self-cleaning electrochemical ratiometric microfluidic paper-based analytical device (SER-μPAD) has been constructed for manganese super oxide dismutase (MnSOD) gene detection on the basis of the inner reference probe and exonuclease Ш (Exo Ш)-assisted analytes recycling amplification method. To simplify manual operations, a multipath self-cleaning tab that could manipulate fluid transport was introduced into the paper-based device, realizing time-programmable self-cleaning of the electrode. For achieving sensitive detection of MnSOD gene, the methylene blue (MB)-modified capture probe (CP) as the inner reference element was first self-assembled on triangular Au nanosheets modified paper working electrode to provide a built-in correction and improve the detection accuracy. When MnSOD gene existed, it hybridized with the hairpin-structured signal probe, triggering the cyclic amplification with the assistance of Exo Ш selective digestion to engender numerous residual DNA labeled with ferrocene (Fc) that could be captured on electrode surface by CPs. Hence, the Fc tags were close to the electrode surface, resulting in the oxidation peak current of Fc (IFc) increase, while that of MB (IMB) was constant on account of the unchanged distance between the MB tags and the electrode. The value of IFc/IMB was linear with MnSOD gene concentration from 10 nM to 1200 nM, and the detection limit was 3.91 nM. This strategy provides an accurate, robust, and sensitive method for nucleic acids detection and shows great potential in the construction of portable devices.

Impact of Element Pattern on the Performance of GNSS Power-Inversion Adaptive Arrays

Power-inversion (PI) adaptive arrays are widely used in Global Navigation Satellite System (GNSS) receivers for interference mitigation. The effects of element patterns on the performance of PI adaptive arrays are investigated in this paper. To this end, the performance of adaptive arrays is investigated by Monte Carlo simulations, using CST Microwave Studio (Dassault Systems, Vélizy-Villacoublay, France) to calculate the radiation patterns of circular microstrip elements which are used to compute the adaptive weight and the adaptive array gain. It is shown that the performance of PI adaptive arrays is mainly dependent on the gain pattern of the reference antenna element rather than the non-reference elements because the algorithm essentially pushes the elements into an unequal position. Furthermore, the results show that the impact of mutual coupling on the performance of the antenna array can be associated with the radiation patterns of the reference element, which is helpful in selecting the optimum reference element without increasing computational complexity, especially for small GNSS arrays.

The influence of body mass on its elemental status

The study is devoted to assessing the effectiveness of the developed methodology for the multivariate analysis of the mutual influence when identifying of the elemental status of an organism. In a multidimensional space, the coordinates of which are the concentrations of elements, patients with the same body mass are located on the hyperplane. In order to carry out calculations related to the assessment of the influence of mass, it is necessary to break up a cloud of patient data on the hyperplates in increments of mass. As a reference element, when estimating the distance of the calculated point for each hyperplate, the beam of norms is chosen as introduced in the previous study, and the angle of rotation of the beam drawn to the calculated point is measured from the intersection line of the plane of equal mass and the plane of a given concentration. The calculations take into account only areas of high or low concentration of the element. In this case, the intersection lines of the plane of equal mass and the planes of a given concentration of each element form a set of rays on the plane of equal mass. The position of the calculated point in relation to this population allows us to assess the degree and direction of the influence of the selected element on all others. The advantage of the developed technique is the reduction of multidimensional analysis to the evaluation of two parameters - distance and angle of rotation.

Identificación de conflictos de uso de suelo para la planificación del crecimiento urbano: ciudad Cuauhtémoc, Chihuahua (México)

Esta investigación incorpora nuevas formas de análisis para la planificación y desarrollo urbano en Ciudad Cuauhtémoc, Chihuahua (México), aportando elementos de referencia mediante la identificación de zonas con potencialidad y limitaciones para el uso de suelo urbano, así como para las actividades agrarias y de conservación. El objetivo general fue identificar los principales conflictos entre los usos y coberturas de suelo para determinar las áreas de mayor aptitud territorial para el crecimiento de la ciudad. Para este propósito se utilizó el modelo Land Use Conflict Identification Strategy (LUCIS) con el fin de entender el significado espacial del estatus de las políticas de uso de suelo, incluyendo los patrones urbanos probables asociados con las tendencias agrarias y de conservación. En el caso de estudio se estima un total de 149.139 habitantes para el año 2030, lo que representa la necesidad de 392,42 hectáreas adicionales para albergar el crecimiento poblacional. Para ello de las 16.272,21 hectáreas que tiene el límite de población, el 38% se asignaron a la categoría de agraria, el 11,95% a suelos de conservación y el 49,67% a suelo urbano (incluyendo el área urbana existente). Existe una porción importante del área que se encuentra en conflicto entre los diferentes usos de suelo. Se concluye que la integración de un modelo de resolución de conflictos de cobertura y uso de suelo representa una solución práctica que contribuye a la mejora de los procesos de planificación del desarrollo urbano.

Speckle pattern shifting deflectometry based on digital image correlation.

A method based on digital image correlation (DIC) for the surface shape measurement of specular surface by shifting a speckle pattern, which is displayed on an LCD screen, is proposed in this paper. With this method, the deformed information of test surface is encoded within the displacement distribution between the two recorded speckle images before and after the speckle pattern shifted. The displacement distribution is calculated by the DIC algorithm, then the slope data and the surface shape are obtained. The principle and algorithm of speckle pattern shifting deflectometry (SPSD) are described in detail. The correctness and feasibility of the proposed method are verified by simulation, and the source of error is analyzed as well. Finally, the shape of an acrylic plastic plate and a silicon wafer are measured. The experimental result of the proposed method is compared with that of PMD, and the figure error is around 1μm RMS with a measured diameter of about 100mm. This method has the advantages of fast measurement, simple device, low cost and needlessness of reference element. It provides a new approach to measure the shape of specular surface.

High order direct Arbitrary-Lagrangian-Eulerian (ALE) PNPM schemes with WENO Adaptive-Order reconstruction on unstructured meshes

In this work we present a conservative WENO Adaptive Order (AO) reconstruction operator applied to an explicit one-step Arbitrary-Lagrangian-Eulerian (ALE) discontinuous Galerkin (DG) method. The spatial order of accuracy is improved by reconstructing higher order piecewise polynomials of degree M>N, starting from the underlying polynomial solution of degree N provided by the DG scheme. High order of accuracy in time is achieved by the ADER approach, making use of an element-local space-time Galerkin finite element predictor that arises from a one-step time integration procedure. As a result, space-time polynomials of order M+1 are obtained and used to perform the time evolution of the numerical solution adopting a fully explicit DG scheme.To maintain algorithm simplicity, the mesh motion is restricted to be carried out using straight lines, hence the old mesh configuration at time tn is connected with the new one at time tn+1 via space-time segments, which result in space-time control volumes on which the governing equations have to be integrated in order to obtain the time evolution of the discrete solution. Our algorithm falls into the category of direct Arbitrary-Lagrangian-Eulerian (ALE) schemes, where the governing PDE system is directly discretized relying on a space-time conservation formulation and which already takes into account the new grid geometry directly during the computation of the numerical fluxes. A local rezoning strategy might be used in order to locally optimize the mesh quality and avoiding the generation of invalid elements with negative determinant. The proposed approach reduces to direct ALE finite volume schemes if N=0, while explicit direct ALE DG schemes are recovered in the case of N=M.In order to stabilize the DG solution, an a priori WENO based limiting technique is employed, that makes use of the numerical solution inside the element under consideration and its neighbor cells to find a less oscillatory polynomial approximation. By using a modal basis in a reference element, the evaluation of the oscillation indicators is very easily and efficiently carried out, hence allowing higher order modes to be properly limited, while leaving the zero-th order mode untouched for ensuring conservation.Numerical convergence rates for 2≤N,M≤4 are presented as well as a wide set of benchmark test problems for hydrodynamics on moving and fixed unstructured meshes.

Determination of Heavy Metal Geochemical Baseline Values and Its Accumulation in Soils of the Luanhe River Basin, Chengde

A total of 351 surface soil samples (0-20 cm) were collected from the Luanhe River Basin in Chengde City (a typical area of concentrated mineral resources) and analyzed for 12 heavy metals (Cu, Ni, Cd, Cr, Pb, Zn, Hg, V, Ti, Mn, As, and Co). The geochemical baseline values of the heavy metals were determined using the reference element method and the cumulative frequency curve method. Furthermore, the spatial structure and distribution characteristics of the heavy metals were assessed based on PCA and geostatistical analysis. The accumulation of heavy metal pollution in different types of soil and in association with different land use patterns was also evaluated using a geological accumulative index. The results showed that the geochemical baseline values of V, Ti, Cd, Pb, Mn, and Co in the surface soils of the Luanhe River Basin were higher than their background values for Hebei Province. In contrast, the geochemical baseline values of As, Zn, Cr, Cu, Ni, and Hg were lower than their background values. The average accumulation index of the surface soils followed the order of Cd > Pb > Cu > Ti > Mn > Zn > Cr > Ni > Co > V > Hg > As. More than 80% of the soil samples were categorized as having no accumulation or moderate accumulation of Pb, Ti, V, As, and Co, while over 70% of the soil samples were categorized as having no accumulation or moderate accumulation of Hg, Mn, Ni, Cu, As, Cd, and Cr. With respect to different soil types, the average accumulation index of heavy metals followed the order of fluvo-aquic soil>cinnamon soil>brown soil. With respect to land use types, the accumulation index of heavy metals followed the order of industrial and mining land > shrub forest land > agricultural land > woodland and grassland. The accumulation of Pb and Cd in the surface soils of agricultural land was relatively high in comparison to the other elements, with 27.69% and 25.38% of the samples being above the moderate accumulation level, respectively. The iron group elements Ti, V, Co, Ni, and Cr are likely to derive from naturally high geological background sources, while the spatial patterns of Cd, Pb, Zn, Mn, Cu, and As were associated with the combination of parent material and anthropogenic inputs. The accumulation of Hg was mainly influenced by human activities.

A boronic acid carbon nanodots/poly(thionine) sensing platform for the accurate and reliable detection of NADH

In this work, a novel electrochemical sensing platform was designed and fabricated by the modification of boronic acid functionalized carbon nanodots (B-CNDs) and poly(thionine) (pTHI) on an electrode surface. B-CNDs can not only accelerate electron transfer but also covalently interact with cis-diol groups of dihydronicotinamide adenine dinucleotide (NADH) through functionalized boronic acid groups. Meanwhile, pTHI served as an inner reference element to provide a built-in correction, which enabled the sensor to detect NADH with high accuracy and reliability based on a ratiometric signal (∆INADH/∆ITHI). The electrochemical experimental results demonstrated that the ratiometric strategy-based sensor possessed good selectivity and high sensitivity. A linear range of 5.0 × 10−7 - 2.0 × 10−4 mol/L for NADH detection was obtained with a limit of detection of 1.5 × 10−7 mol/L. The sensor has been applied to analyze NADH in human serum samples with satisfactory results. The simple and effective ratiometric strategy reported here can be further used to prepare electrochemical sensors for selective, sensitive, and reliable detection of other cis-diol compounds.

ELEMENTOS POTENCIALMENTE TÓXICOS (Cd, Hg, Pb Y Zn) EN SUELOS IMPACTADOS POR PLANTA RECICLADORA DE PLOMO (ZACATECAS, MÉXICO), A UNA DÉCADA DE PARAR OPERACIONES

Cadmium (Cd), mercury (Hg), lead (Pb) and zinc (Zn) were analyzed in 75 samples of surrounding soils (7 km2) to a lead recycling plant out of operation in Fresnillo, Zacatecas, and five samples of a non-impacted soil to obtain the background regional values. Aluminum (Al) was used as a reference element for the calculation of enrichment factors (EF). A high variability was observed in the concentrations of Cd (0.02 - 9.11 μg/g), Hg (< D.L, - 2.91 μg/g), Pb (8.9 - 9216 μg/g) and Zn (31.2 - 465 μg/g). A high association was observed between Cd, Pb and Zn, but not with Al and Hg. There was an inverse association with the factory distance for the concentrations of Cd and Pb, but not for Hg and Zn. This indicates that the source of Cd and Pb was the recycling plant, while Hg and Zn may have other anthropogenic sources and/or a different behavior. Cd and Pb show a clear trend to accumulate towards the west-northwest direction. There was a significant decrease in Pb with respect to the maximum levels in 2004 (from 84 238 μg/g to 9216 μg/g) within the factory land. Even so, the FECd and FEPb varied from natural to contaminated and the contamination extends to ~ 0.5 km towards the W - NW. FEHg and FEZn were from natural to enriched levels. The high concentrations of Cd and Pb in and out of the occupied plant land make necessary the continuous monitoring of the impacted area given the potential transport of the dust to nearby populations.

Variational Interpolation of Functionals in Transport Theory Inverse Problems

It is known that dual representation of problems (through the main function and its adjoint in the Lagrange sense) makes it possible to formulate an effective perturbation theory on which the successive approximation method in the inverse problem theory relies. Let us suppose that according to preliminary predictions, a solution to the inverse problem (for example, the structure of medium of interest) belongs to a certain set A. Then selecting a suitable (trial, reference) element a0 as an unperturbed one and applying the perturbation theory, one can approximately describe the behavior of a solution to the forward problem in this domain and find a subset A0 that matches the measurement data best. However, as the accuracy requirements increase, the domain of applicability of the first approximation A0 is rapidly narrowing, and its expansion via addition of higher terms of the expansion complicates the solving procedure. For this reason, a number of works have searched for unperturbed approaches, including the method of variational interpolation (VI method). In this method, not one but several reference problems a1, a2,...,an are selected, from which a linear superposition of the principal function and the adjoint one is constructed, followed by determination of coefficients from the condition of stationarity of the form of the desired functional representation. This paper demonstrates application of the VI method to solving inverse problems of cosmic rays astrophysics in the simplest statement.

IUPAC Expansion from 1957 to 1975

Abstract To chemists and chemical educators, there were two important events in the ‘60s and ‘70s. First, in 1961, the agreement between physicists and chemists on the choice of carbon 12 as unique element of reference in the atomic weights table and then in 1971, the definition of mole as the seventh unit of the international system [1]. In both of these issues the Union played its role as expert to the fullest, and established solid grounds for a common language of chemistry across the world. This role is also extended to other matters at a time marked by social changes. Technological progress improved quality of life like never before and the space conquest that opened new horizons, both scientific and technological, to explore. All the while, despite the Cold War, international and interdisciplinary projects are established, and new international organizations, such as UNESCO, appear to cope with the new challenges. Alongside these organizations, the longstanding ICSU and the Union adapt themselves.

Finite element analysis of maxillary anterior teeth retraction of posterior teeth with different alveolar bone absorption heights under orthodontic force

This study applied the direct orthodontic force system to explore the applicability of the finite element method in the simulation of alveolar bone absorption and analyze periodontal stress distribution and the overall displacement trend. The horizontal balanced alveolar bones of model 2, 3 and 4 were reduced by 2, 4, and 6 mm by deleting elements in reference to the established height of the normal alveolar bone model 1. Then, stress distribution on the posterior set of teeth and initial total tooth displacement under the simulated load of 1.47 N of orthodontic force were investigated. The total displacement of posterior teeth increased and parodontium Von Mises stress gradually increased as the alveolar bone height decreased. The total displacement trend and parodontium stress drastically increased when alveolar bone absorp-tion reached the height of 4 mm. When treating patients with alveolar bone loss, stress should be avoided or drasti-cally reduced to prevent irreversible damage to periodontal tissue and to improve the quality of medical treatment.

Adaptive Sliding Mode Controller Design for a Tunable Capacitor Susceptible to Unknown Upper-Bounded Uncertainties and Disturbance

Uncertainty in physical parameters of a tunable MEMS capacitor, as the main element of MEMS AC voltage reference (VRS), is a significant matter to be regarded in order to obtain a precise output voltage which could be ruined by disturbance and noise. Even though many attempts are done to make MEMS tunable capacitor with desired precise physical characteristics and improve accuracy of values in physical parametric properties, parametric uncertainties inevitably transpire in manufacturing process due to shortcomings in micromachining procedures. Not only does this paper take into account design of a PI adaptive sliding mode controller and its application for the MEMS AC VRS in such a way that it is competent of producing a stable precise regulated output voltage in the presence of uncertainties and exogenous disturbance, but also it conquers both terms of matched and unmatched uncertainties and disturbance which their upper bounds are limited but not known. The matched and unmatched disturbance may emerge in the device dynamics because of cross-talk, inertial coercions and electrostatic disturbing forces. The matched uncertainties, such as change in stiffness and damping factors, may exist because of alteration in manufacturing process or even operational situations. The simulation yields in the article are very convincing that the controller design has demonstrated a persuasive tracking performance and has resulted in a well regulation about the pull-in working point.

Mixed beam formulation with cross-section warping for dynamic analysis of thin-walled structures

This paper presents the formulation of a three-dimensional beam finite element (FE) that accounts for cross-section warping and dynamic inertia effects. The model is the extension of an existing mixed formulation, originally developed for the static analysis of thin-walled beams, to the case of dynamic loading conditions.Four independent fields are considered to derive the element governing equations, i.e. material rigid displacements, strains and stresses and an additional displacement field, describing the out-of-plane warping displacement of the beam cross-sections. The latter is independently interpolated in the element volume by including additional degrees of freedom (DOF) to the nodal translations and rotations classically considered in beam formulations.To obtain a consistent form of the element mass matrix, the cross-section displacement shape functions are computed, relating the generalized cross-section displacement fields to the element nodal variables. In mixed FE formulations, these are not assigned a priori, as in displacement-based approaches, but are derived on the basis of material stiffness and element geometry, together with compatibility conditions. Thus, the Unit Load method is applied to deduce the expressions of the shape functions consistent with the force-based approach, assuming the simply-supported beam as reference element configuration.As opposed to the original FE model, the additional warping DOFs are not condensed-out with the definition of the element quantities but are treated as additional global unknowns. This permits a correct description of the inertia effects and ensures continuity of the warping displacement fields between adjacent FEs.Correlation studies are presented to validate the proposed model and investigate the effects of cross-section warping on the dynamic behavior of thin-walled structures. For selected specimens, the studies compare solutions obtained adopting the proposed beam element with those resulting from shell or brick FE models. Modal decompositions and time-history analyses are conducted, assuming both linear elastic and nonlinear constitutive behavior for the latter.

EVALUATING THE EFFECTIVENESS OF THE TUMOR-INITIATING STEM CELLS ERADICATION STRATEGY ON THE EXAMPLE OF HUMAN GLIOBLASTOMA CELL LINE U87

The effectiveness of the new therapeutic approach aimed at the destruction of the cancer cell community was evaluated on the immortalized human glioblastoma cell line U87. Initially, the reference elements of a new strategy for eradication of tumor-initiating stem cells were characterized. The main points of the strategy were as follows. 1) Evaluation of the TAMRA+ (tumor-initiating stem cells) presence in the population of U87 culture cells. 2) Determination of the reference time points of the DNA interstrand cross-links repair, induced by cross-linking cytostatics mitomycin C. 3) Determination of the day after initiation of therapy when TAMRA+ cells accumulate and are synchronously present in the G1/S sensitive for the treatment phase of the cell cycle. Based on the data obtained, a therapeutic regimen aimed at eradicating TAMRA+ cells (tumor-initiating stem cells) was identified. Treatment of the culture was carried out by cross-linking cytostatic mitomycin C and complex DNA preparation. Transplantation experiments showed that high experimental doses of mitomycin C (20 μg/ml) totally destroy transplantation potential of U87 cells. Diminution of mitomycin C to therapeutic doses (5 μg/ ml) clearly demonstrated effect of complex double-stranded DNA preparation to reducing of U87 tumorigenic potential. These fully confirmed the concept of developed cancer treatment technology.

Mechanical Properties of Laminated Veneer Lumber Beams Strengthened with CFRP Sheets

AbstractThis paper presents the results of the static work analysis of laminated veneer lumber (LVL) beams strengthened with carbon fabric sheets (CFRP). Tested specimens were 45mm wide, 100 mm high, and 1700 mm long. Two types of strengthening arrangements were assumed as follows: 1. One layer of sheet bonded to the bottom face; 2. U-shape half-wrapped reinforcement; both sides wrapped to half of the height of the cross-section. The reinforcement ratios were 0.22% and 0.72%, respectively. In both cases, the FRP reinforcement was bonded along the entire span of the element by means of epoxy resin. The reinforcement of the elements resulted in an increase in the bending strength by 30% and 35%, respectively, as well as an increase in the global modulus of elasticity in bending greater than 20% for both configurations (in comparison to the reference elements).

Somatic symptom disorder and health care utilization in the general population

The paper presents the analysis of the impact of silica fume content in high-performance concrete (HPC) on bond conditions along the height of tested elements. The tests were performed on the specimens made of six different HPC mixes with varying content of silica fume (0, 5 and 10% by mass of cement) and superplasticizer. The used specimens allowed for determining the changes of bond at individual levels of elements with a total height of 480 and 960 mm. The rebars in the elements were placed perpendicularly to the direction of concreting. The reference element, characterised by the parallel orientation to the direction of concreting, was also prepared. The tests indicated that the quality of bond conditions in HPC deteriorates as the distance from the formwork bottom increases. The experiment results indicate that concrete modification with silica fume can both increase and decrease the quality of bond conditions. The influence of silica fume depends on the thickness of the concrete cover, which determines the mechanism of bond failure.