Discontinuous Research Articles

A color representation of two-dimensional discontinuous seismic structures

We present a computational procedure to represent with colors two-dimensional piecewise continuous functions. Seismic wave velocities are used as examples. Vertically and laterally heterogeneous layers are separated by structural discontinuities. Vertical lines divide each layer into trapezoidal cells; the non-parallel sides are the interfaces. A bivariate function is parametrized by assigning a value to each trapezoid vertex. The value at any point inside a trapezoid is obtained by linear interpolations applied along the non parallel sides up to the vertical line passing through the point and, then, along this line. Based in this already reported interpolation scheme, the procedure searches at each layer for points associated with a specific value range of the seismic parameter being represented; the resulting contiguous points define on area which is filled with a unique color from a palette. This procedure gives an accurate representation of a smooth, bivariate function with finite step discontinuities along layer interfaces, and does not introduce spurious features in the interpolation/smoothing numerical process.

Modeling and design of a capacitive microwave power sensor for X-band applications based on GaAs technology

In the work, modeling and design of a capacitive microwave power sensor employing the MEMS plate with clamped–clamped and free–free edges are presented. A novel analytical model of the sensor is established in detail. Through the function of mode shapes presented, the natural frequency can be solved by the Rayleigh–Ritz method. And based on the generalized coordinate introduced, the displacement of the plate with the irradiation of microwave power can be solved. Furthermore, the sensitivity for the power is also derived. Then the detailed consideration of the design and simulation of the microwave characteristic of the sensor are also presented. The linearly graded ground planar in the coplanar waveguide is employed to avoid step discontinuity. The fabrication process is compatible with GaAs MMIC technology completely, also described in detail. The measurement of the proposed sensor indicates a sensitivity of 7.2 fF W−1 and superior return and insertion losses (S11 and S21), less than −22.16 dB and −0.25 dB, respectively, up to 12 GHz, suggesting that it can be available for microwave power detecting in the X-band frequency range.

Inhibiting effects on invasion and metastasis of melanoma by CXCR4 gene silence in nude mice

Objective To study the inhibiting effects on the invasion and metastasis of melanoma by CXCR4 gene silence in nude mice.Methods The CXCR4 specific recombinant plasmid vector was constructed and transfected into the cultured MV3 cell line with lipofectamine.The models of subcutaneous melanoma in nude mice were established with MV3 cells.The nude mouse model of lung metastasis was established by injection of MV3 cells into the tail vein.The animals were sacrificed at 8weeks after the melanoma cells injection.CXCR4-shRNA plasmid vectors were discontinuously injected directly into the established tumor and vein.The changes of weight and size of the tumors and the mice body weight during the therapy were calculated respectively.Histological observation was performed to evaluate the presence and number of metastatic tumors.Results The subcutaneous melanoma tumors in nude mice were established successfully.The growth of tumors in the CXCR4-shRNA injected nude mice was inhibitted obviously through tumor growth curve. There were significant differences between negative shRNA control nude mice and blank control nude mice (P＜0.01).Melanoma cells with CXCR4 shRNA permanent transfection had a much lower lung and brain and liver metastatic potential in nude mice than control cells and mock control cells in vivo.Conclusions CXCR4 gene silencing mediated by shRNA significantly suppresses the growth of MV3 cell in vitro.Silencing of CXCR4 mediated by shRNA can also effectively decrease the metastatic potential of lung and liver and brain. Key words: Melanoma; Chemokin receptor CXCR4; Gene silencing; Tumor metastasis

A nodal discontinuous Galerkin method for computational aeroacoustics and comparison with finite difference schemes

A nodal discontinuous Galerkin formulation, which is based on Lagrange polynomials basis, is used to directly simulate the acoustic wave propagation. Two test problems of wave propagation with initial disturbance consisting of a Gaussian profile or rectangular pulse are investigated. We evaluate the performance of the schemes in short, intermediate, and long waves. Moreover, the comparisons of numerical results between the nodal discontinuous Galerkin method and finite difference type schemes are performed, which indicate that the numerical solution obtained using nodal discontinuous Galerkin method with a pure central flux has obvious high frequency oscillations for initial disturbance consisting of rectangular pulse, which is the same as those obtained using finite difference type schemes without artificial selective damping. If an upwind flux is adopted, spurious waves are eliminated effectively except for the location of discontinuities. When a limiter is used, obviously the spurious short waves are almost completely removed. The quality of the computed solution has greatly improved.

Investigation on Chip Formation during Machining Using Finite Element Modeling

Titanium alloys are desirable materials for aerospace industry because of their excellent combination of high specific strength, lightweight, fracture resistant characteristics, and general corrosion resistance. Therefore, the chip morphology is very important in the study of machinability of metals as well as the study of cutting tool wear. The chips are generally classified into four groups: continuous chips, chips with built-up-edges (BUE), discontinuous chips and serrated chips. . The chip morphology and segmentation play a predominant role in determining machinability and tool wear during the machining process. The mechanics of segmented chip formation during orthogonal cutting of titanium alloy Ti–6Al–4V are studied in detail with the aid of high-speed imaging of the chip formation zone. The finite element model of chip formation of Ti–6Al–4V is suggested as a discontinuous type chip at lower cutting speeds developing into a continuous, but segmented, chip at higher cutting speeds. The prediction by using finite-element modeling method and simulation process in machining while create chips formation can contribute in reducing the cost of manufacturing in terms of prolongs the cutting tool life and machining time saving.

Effect of environmental conditions on field welding of precast concrete connections

A research study was conducted to investigate the quality of welded connections between precast concrete components made under environmental conditions typically encountered in precast concrete construction. The effects of wind, humidity, tempera- ture, and surface moisture on the quality of shielded metal arc welds (SMAWs) were examined. The study focused on ASTM A36 Type 304 stainless steel and ASTM A36 galvanized steel plates. Weld surfaces and cross sections were examined visually and with optical microscopy. The results of the examinations were com- pared with limits for various weld discontinuities in accordance with American Welding Society specifica- tions D1.1 and D1.6. In addition, tests were performed to assess the impact of environmental conditions on strength. The results showed that good quality SMAW welds can be made in wind up to 35 mph (56 kph), in temperatures as low as -10 °F (-23.3 °C), and under wet conditions. In general, acceptable welds were fabricated under the variety of environmental condi- tions examined. Various types of discontinuities were observed but were not found to cause a significant reduction in the transverse shear strength of the welds.

The study of the insulin secretory function of the bioartificial pancreas in vitro

Objective To explore the impact of insulin secretory function of adult islet cells from barium-alginate microencapsulation in vitro. Methods After weighting the pancreas,human pancreatic islets were isolated with type V collagenase and purified by Ficoll's discontinuous density gradient centrifugation.The islet cell yield and purity were evaluated with microscope by DTZ staining.Human islets were coated by barium-alginate microencapsulation,and the viability was assessed by insulin release assay in vitro.Results After isolation,the average number of islet was about 3600 ±447 per gram pancreas.It was about 2140±207 after purification with more than 70％ purity.At day 2,4 and 6 after islet cell culture in vitro,basal insulin concentrations from the culture medium was measured,and the mean insulin concentration (mU/L) in media of the microencapsulated islet group at 2nd,4th and 6th day were 3.302±1.63、3.504±1.10 and 2.921±1.13 respectively,and those non-microencapsulated islet group were 3.814 ± 1.49、4.175 ±1.60、3.617± 1.34.There were no significant differences between these two groups (P＞0.05).Conclusions The bioartificial pancreas has effective insulin secretory function in vitro without being affected by barium-alginate microencapsulation. Key words: Bioartificial pancreas; Islet; Insulin,secretory

Runge–Kutta discontinuous Galerkin method for the approximation of Baer and Nunziato type multiphase models

A high-order numerical method is developed for the computation of compressible multiphase flows. The model we use is based on the Baer and Nunziato type systems [4]. Among all the other available models in the literature, these systems present the advantage to be able to simulate either interface or mixture problems. Nevertheless, they still raise some issues, mainly based on their non-conservative feature. The numerical method we propose is a discontinuous Galerkin type. In this work, the interior side integrals are computed thanks to [2]. Robustness and high order of accuracy of the method are proved on classical interface problems, but also on suitably derived analytical solutions.

On the interpolation of discontinuous functions

Given a sequence of real numbers, we consider its subsequences converging to possibly different limits and associate to each of them an index of convergence which depends on the density of the associated subsequences. This index turns out to be useful for a detailed description of some phenomena in interpolation theory at points of discontinuity of the first kind. In particular we give some applications to Lagrange operators on Chebyshev nodes of the first and the second kind and Shepard operators.

CT feature of microcarcinoma of thyroid

Objective To evaluate the imaging feature of microcarcinoma of thyroid with CT.Methods CT findings of 50 lesions in 47 patients with microcarcinoma of thyroid ( dimeter,0.5 to 1.0 cm) were retrospectively analyzed.All of the patients had pathological diagnosis.Results Of the 50 lesions,38 lesions showed homogeneous low density on non-enhanced CT and various degree of enhancement on postcontrast CT. Thirty-three lesions showed discontinuous edge of the thyroids on non-enhanced CT. The boundary of 30 lesions became unclear on post-contrast CT relative to non-enhanced CT and the extension of low density of lesions decreased. Theshape of 31 lesions were irregular. Fifteen lesions showed calcifications,with granular calcifications in 13 lesions.Ten lesions were complicated with thyroiditis.Conclusions Irregular shape,discontinuous edge of the thyroids,the shrinkage of low density of lesions on post-contrast CT relative to non-enhanced CT,granular calcifications and multiple small lymph node around lesions indicate the diagnosis of microcarcinoma of the thyroid.It should be noted that thyroiditis can cover up microcarcinoma of thyroid. Key words: Thyroid neoplasms; Tomography,X-ray computed

Boundary Integral Computation of Elastic Water Resisting Key Strata under the Condition of Discontinuous Load

Boundary Integral Computation of Elastic Water Resisting Key Strata under the Condition of Discontinuous Load

ENHANCING THE MASS SENSITIVITY OF NANOCANTILEVER

In the present work, dynamic frequency analysis of different nanostructures like nanobelt, nanotube etc., which can be attached to a conventional micro cantilever, is performed for estimating the mass sensitivity using finite element analysis. It is found that compared to rectangular bar and cylinder shape, tube shape gives higher sensitivity and is explained on the basis of distribution of effective mass. In the case of nanocantilever, it is found that by introducing a step discontinuity along the length of the cantilever, mass sensitivity can be enhanced. It is also proved that mass sensitivity is highly dependent on the position of mass loading in cantilever based mass sensors.

Discontinuity surfaces recorded in shallow-marine platform carbonates: an example from the Early Jurassic of the Velebit Mt. (Croatia)

Discontinuity surfaces of different types and scales are common in successions of shallow-marine carbonate platforms because sediments there are deposited close to the sea level and therefore are sensitive to any significant physico-chemical changes of environmental factors. Discontinuity surfaces indicate breaks in sedimentation under subaqueous or subaerial conditions. Most discontinuities in shallow-marine carbonate successions are on a bed-scale, and can be determined only by analysis of sedimentologic, diagenetic, taphonomic, and ichnologic features of the rock. The study of small-scale discontinuities has been carried out on two Lower Jurassic successions of the Velebit Mt. Depending upon their common features and environment of formation, three groups of discontinuities are distinguished on simple bedding planes: subaerial exposure surfaces, erosion surfaces, and omission surfaces. The distribution of discontinuity types in both successions is evaluated. Exposure surfaces prevail in both sections, and four units (relatively thin intervals of the sedimentary record) with abundant subaerial exposures are recognized. Dated by biostratigraphy, these units are of earliest Sinemurian, middle Early Sinemurian, earliest Pliensbachian, and late Early Pliensbachian age. Omission surfaces are the least common type of discontinuity. Thickness variations of high-frequency peritidal and shallow subtidal shallowing-upward cycles, highlighted by the Fischer plots show a very similar long-term trend for the two sections. The units with common subaerial exposure surfaces coincide with the falling limb of the Fischer plots and the section with common omission surfaces coincides with the rising limb of the plots. The studied discontinuities are formed by autocyclic and/or allocyclic processes operating on the shallow platform, but the units with abundant subaerial exposures invoke allogenic forcing of the sedimentary record. The use of the units with abundant discontinuities instead of a single surface has proven useful for the correlation of the studied shallow-platform deposits because one type of discontinuity may change laterally into another type or features of different discontinuity types can be superimposed.

Large Deviation Principles for Random Walk Trajectories. I

This paper deals with a random walk $S_n:=\xi_1+\cdots+\xi_n$, $n=0,1,\ldots,$ in the $d$-dimensional Euclidean space ${\mathbb R}^d$, where $S_0=0$ and $\xi_k$ are independent identically distributed random vectors satisfying Cramér's moment conditions. For random polygons with nodes at the points $(\frac{k}{n},\frac{1}{x}S_k)$, $k=0,1,\ldots,n,$ we obtain the logarithmic asymptotics of the large deviation probabilities in different trajectory spaces when $x\sim \alpha_0 n$, $\alpha_0>0$, as $n\to\infty.$ The results include the so-called local and extended large deviation principles (l.d.p.'s) (see i̧te15) that hold in those cases where the “usual” l.d.p. does not apply. The paper consists of three parts. Part I has two sections. Section 1 presents the key concepts and some facts concerning the l.d.p. in arbitrary metric spaces. In section 2 we formulate the “strong” versions of the “usual” l.d.p. in the large deviation zones that were obtained earlier in [A. A. Borovkov, Theory Probab. Appl., 12 (1967), pp. 575--595], [A. A. Mogul'skii, Theory Probab. Appl., 21 (1976), pp. 300--315] for the space of continuous functions. Besides that, section 2 also contains the l.d.p. for probabilities for the random walk trajectories to hit a convex set. That result was obtained using inequalities from [A. A. Borovkov and A. A. Mogul'skii, Theory Probab. Appl., 56 (2012), pp. 21--43] and does not involve any moment conditions. Part II begins with section 3 presenting an example elucidating the need to extend both the problem formulation and the very concept of the “large deviation principle.” We introduce a new extended functional space, a metric therein, and the deviation functional (integral) of a more general kind that will be used when constructing an “extended” l.d.p. In section 4 we present and prove the key results of the paper, the local and the extended large deviation principles, for the trajectories of univariate random walks in the space ${\mathbb D}$ of functions without discontinuities of the second kind. Section 5 extends to the multivariate case all the results established in section 4. Section 6 in Part III presents results analogous to those from section 4, but now established in the space of functions of bounded variation with a metric stronger than that in $\mathbb D$. In section 7 we establish the so-called conditional large deviation principles for the trajectories of univariate random walks given the location of the walk at the terminal point. As a consequence, we obtain the Sanov's theorem on large deviations of empirical distributions.

A Study on Auxiliary Pole Installation of Concentrated Winding PMLSM with Bifurcating of Armature Teeth

Recently, linear motors have been widely researched and have been increasingly used in various industrial applications. Especially, permanent magnet linear synchronous motors(PMLSMs) have been getting the spotlight in the transportation system. A PMLSM is structurally simple and has a lot of merits such as high speed, high thrust force, etc. However, in case of a long stator system which arranges armature to the full length of transportation lines, a PMLSM has some disadvantages such as the material cost increase and long manufacturing time. Hence, in order to overcome these problems, the PMLSM with stationary discontinuous armature structure and concentrated windings was proposed. However, this method occurs undesirable cogging force by outlet edge effect. The cogging force causes thrust force ripples and generates noise and vibration. Therefore, in this paper, we proposed installation method of auxiliary pole PMLSM with concentrated winding applying bifurcating in order to reduce cogging force by the outlet edge when the armature is placed in a discontinuous arrangement. Also, we have examined characteristics of outlet edge cogging force using 2-D finite element analysis(FEA).

Searching Discontinuous and Jump Points in Physical Discontinuities with Adaptive Phase Unwrapping

AbstractThis study proposes a method of detecting discontinuous points in physical discontinuities in light intensity fringe pattern (IFP). After changing the experimental conditions, several images were captured with CCD and converted into wrapped phase maps with phase shifting technology (PST). In low-noise wrapped phase maps, discontinuous and jump points were searched directly; and in high-noise wrapped phase maps, these points were searched after filtering. Noise discontinuous points were screened by image comparison to correctly select physical discontinuous points. The location of physical discontinuities was marked according to the assembly principle to prevent diffusion on both sides along the discontinuous line by phase unwrapping from crossing the line. In doing so, the surface appearance of the specimen was phase unwrapped successfully.

Выбор рациональных параметров вибрационной очистки поверхностей просеивания при классификации материалов

В работе приводится динамическая схема вибрационной очистки поверхностей просеивания при классификации сыпучего материала. На основе анализа динамических свойств системы вибрационной очистки разработана методика и программа расчета рациональных параметров прерывистого силового возмущения. Исследованы коэффициенты динамичности системы для различных областей частот колебаний вибровозбудителя: низких и резонансных частот, высоких частот

Parallelism between central and enteric nervous system damage in experimental parkinsonism

Parkinson’s disease (PD) is a neurodegenerative condition which affects dopaminergic neurons of the substantia nigra (SN), leading to a movement disorder. Non motor alterations occur in several viscera, in particular the gastrointestinal tract. In 9-week old C57BL mice we examined the effects of the parkinsonism-inducing neurotoxin 1-methyl, 4-phenyl, 1,2,3,6,-tetrahydropyridine (MPTP, administered either acutely or chronically) in SN and striatum, as well as in duodenum. Motor tests (open field and PaGE) were performed. One week after treatment with MPTP (acute: 20 mg/KgX3, 2h apart or chonic: 5 mg/kg x2/die, for 3 weeks), histological investigations, immunohistochemistry and immunoblotting for tyrosine hydroxylase (TH), and α-synuclein (α-syn) were carried out. Immunocytochemical investigations were analyzed under electron microscopy. Motor tests showed a failure of the PaGE test in all MPTP-treated animals, whereas no difference was found in open field test in comparison with controls. Analysis of histological sections showed some alterations consisting of slight atrophy of duodenal mucosa and glandular disarrangement only after chronic treatment. Under electron microscopy the brush border appeared discontinuous. In all MPTP-administered mice, TH immunopositivity was reduced in SN and striatum, confirming its central dopaminergic neurotoxicity. At duodenal level, TH immunostaining was lost following all MPTP treatments with a slight variation in chronic compared with acute administrations. This was confirmed by semiquantitative immunoblotting. Moreover, α-syn immunostaining was enhanced by MPTP treatment but this was way more evident following chronic administration both at central and peripheral level. Following chronic treatment α-Syn immunopositive structures were investigated under electron microscopy. Our study shows that chronic more than acute administration of MPTP induces alterations at duodenal level reminiscent of dopaminergic damage in SN and striatum. Moreover, this experimental model of parkinsonism features gastrointestinal dysfunction observed in PD patients. These findings lend substance to the concept of the enteric nervous system as a double brain which recapitulates and is an ancestry of the central nervous system.

Sarcoglycan sub-complex in WAG/Rij rats, a model of absence epilepsy: an immunofluorescence study

It is known that even in Central Nervous System the Dystrophin Glycoprotein Complex (DGC) exists but differs in composition from the DGC core present in muscle for the presence of several isoforms of dystrophin and for the existence of a sarcoglycan sub-complex which is made up only for e- and ζ-sarcoglycans; for these reasons it was called “DGC-like”. Although that, in our previous studies we have found that all sarcoglycans are present in human cerebral cortex and in different regions of rat’s brain, suggesting that the composition of the brain DGC is not different from the muscle DGC but differing just for the function. In fact, our previous data showing the colocalization between sarcoglycans and GABAA Re receptors in rat’s cerebral and cerebellar cortex, thalamus and hippocampus suggested us that in brain sarcoglycans could be associated with synaptic neurotransmission. To better understand which kind of relationship between sarcoglycans and GABAA receptors exists, we aim to investigate α-,β-,γ-,δ-,e- and ζ-sarcoglycans and the GABAA Re in the brain of the WAG/Rij rats, a model of absence epilepsy, using immunofluorescence techniques; we have observed cerebral cortex, thalamus and hippocampus, the structures mainly involved in absence epilepsy, comparing this to normal rat’s brain. Results show that the GABAA Re receptors staining pattern is different from the normal rat’s brain presenting an abnormal fluorescence distribution consisting in discontinuous clusters around the cellular body. Sarcoglycans, instead, have shown the typical “spot-like” staining pattern around the cellular body, sometimes colocalizing with GABAA Re receptor; moreover, they seem to have an higher staining pattern than normal rat’s brain. In our opinion these results, showing an alteration of GABAA Re receptor pattern distribution and a normal or increased sarcoglycans staining pattern, allow us to hypothesize that the sarcoglycans in absence epilepsy are likely to compensate for the alteration in GABAA Re receptor distribution. That support the opinion about the involvement of sarcoglycans in cellular signalling and receptor assembly regulating indirectly synaptic neurotransmission both in normal and in pathological condition.

Stress Concentration and tts Mitigation Techniques in Flat Plate with Singularities - A Critical Review

A number of analytical, numerical & experimental techniques are available for the reduction of stress concentration factor around discontinuities. Using various techniques the SCF around different discontinuities in a rectangular plate made up of different materials under different loading conditions have been reported in literature. Mitigation of stress concentration around different types of discontinuity is also reported in literature. This paper is to present an analysis and overview of emerging techniques developed for analysis as well as mitigation of stress concentration. The proposed methods in literature are compared.