Conical Segment Research Articles

Free and forced vibration of ring-stiffened conical–cylindrical shells with arbitrary boundary conditions

An analytic method is presented to analyze free and forced vibration characteristics of ring-stiffened combined conical–cylindrical shells with arbitrary boundary conditions, e.g. classical and elastic ones. The combined shell is firstly divided into multiple substructures according to the junctions of shell–shell and shell–plate, and/or the location of driving point. Then, Flügge theory is adopted to describe the motions of the cylindrical and conical segments. Instead of adopting the smeared out method and treating the ring stiffeners as beams, the stiffeners with rectangular cross-section are treated as discrete members and the equations of motion of annular plate are used to describe the motion of stiffeners. Power series, wave functions and Bessel functions are used to express the displacement functions of conical segment, cylindrical segment and annular plate, respectively. Lastly, boundary conditions and continuity conditions between adjacent substructures are used to assemble the final governing equation. Results of present method show good agreement with the results in literature and the results calculated by finite element method (FEM). In addition, the influences of boundary conditions and ring stiffeners on the free vibration are studied. The effects of direction of external force and bulkheads on the forced vibration are also discussed.

Morphology of the Alimentary Canal of the Leafhopper Cicadella viridis (Hemiptera: Cicadellidae)

The blue-green sharpshooter Cicadella viridis (Linnaeus) (Hemiptera: Cicadellidae) is a significant pest and disease vector of some economically important plants in some parts of its range in the Palearctic and Oriental regions. Its alimentary canal was examined using the light and electron microscopes. The alimentary canal was differentiated into the esophagus, filter chamber, external midgut section, and hindgut. The filter chamber contained a sheath and a filter organ; the former externally surrounding the latter. The filter organ was composed of the anterior and posterior ends of the midgut (internal midgut section), internal proximal ends of the Malpighian tubules, and internal proximal end of the ileum. Two types of cells constituting the internal anterior end of the midgut possessed morphologically different basal infoldings and apical microvilli. Cells of the internal posterior end of the midgut contained concentric structures tentatively identified as modified basal plasma membranes, whereas plasma membranes of the internal proximal ends of Malpighian tubules invaginated into narrow sinuate basal infoldings, though both organs had similar reduced cytoplasm. The external midgut section was divided into a conical segment and a midgut loop. The conical segment cells, which were packed with mitochondria, possessed regularly arranged dense microvilli and shallow infoldings. The midgut loop was subdivided into two regions: 1) an anterior segment, with cells containing abundant electron-lucent secretory granules, ribosome-like particles, and sparse rough endoplasmic reticulum; and 2) a posterior segment, having numerous mitochondria, some lysosome-like granules, well-developed basal infoldings, and apical microvilli. The hindgut emerged from the posterior of the filter chamber and was composed of a pear-shaped rectum and a long narrow ileum. Its cells possessed apical leaflets associated with mitochondria. Microorganisms existing between lamina of the extracellular matrix, in a clearing of ileum cytoplasm and muscle fibers, are probably pathogenic.

Morphology and ultrastructure of the alimentary canal of the cicada Platypleura kaempferi (Hemiptera: Cicadidae)

AbstractThe alimentary canal of cicada Platypleura kaempferi is described. It comprises the oesophagus, filter chamber, external midgut section and hindgut. The elongate oesophagus expands posteriorly, with its posterior end constricting to become a bulb. The filter chamber consists of two parts: a very thin sheath and a filter organ. The filter organ is composed of the anterior and posterior ends of the midgut (internal midgut section), and the internal proximal ends of the Malpighian tubules. The external midgut section differentiates into a collapsed sac and a midgut loop. The latter is divided into three distinct segments. The hindgut contains a dilated rectum and a long narrow ileum. The distal portions of the four Malpighian tubules are enclosed in a peritoneal sheath together with the distal ileum before reaching to the rectum. Ultrastructurally, the oesophagus and the hindgut are lined with a cuticle. The filter chamber sheath consists of cells with large irregular nuclei. Filamentous substances coat the microvilli of the cells of the internal midgut section. The posterior end of the midgut comprises two types of cells, with the first type of cells containing many vesicles and scattered elements of rough endoplasmic reticulum. The anterior and posterior segments of the midgut loop cells have ferritin‐like granules. The ileum cells have well‐developed apical leaflets associated with mitochondria. Accumulations of virus‐like particles enclosed in the membrane are observed in the esophagus, conical segment, mid‐ and posterior segments of the midgut loop.

Numerical Strength Analysis of a Complex, Steel Shell Structure/ Numeryczna Analiza Wytrzymałosciowa Pewnej Złożonej, Stalowej Konstrukcji Powłokowej

Abstract The paper deals with the numerical modelling of a complex, steel shell structure. The part under analysis is the upper segment of a steel pylon, which consists of several cylindrical shells and one conical segment. Particular parts of the structure are welded together. Geometrical and loading data calculations were performed for the particular material for both an ideally elastic case and an elasto-plastic case. The conclusion that the structural member analysed required strengthening were drawn on the basis of these results. The structural modification was proposed and additional calculations for this modified structure were also performed. Introduced additional shell elements locked the mechanism of plastic flow. The proposed modification can be treated as a possible strengthening concept. The whole analysis was performed by means of the ABAQUS system but some stages of calculations were also verified by the COSMOS/M system.

Free vibration of laminated orthotropic conical shell on Pasternak foundation by a domain decomposition method

By a domain decomposition method, free vibration characteristics of laminated orthotropic conical shells resting on Pasternak foundations are analyzed. The conical shell is divided into some conical shell segments in the meridional direction and separated from the geometric boundary and Pasternak foundation; the theoretical model is formulated based on a modified variational functional which includes energy of each conical shell segment, interface potentials (including the boundary potentials) and the energy due to the Pasternak foundation. Numerical comparisons with those published results are made to validate the high accuracy of the present method. The variation of the energy contribution of the shell with different thickness-to-radius ratio, cone angle and fibre orientation against various circumferential wave numbers are presented to help better understand the vibrational characteristics. Moreover, the effects of elastic foundation, boundary condition, stacking sequence and the variations in physical parameters of the shells on the natural frequencies are also investigated.

Anatomy and fine structure of the alimentary canal of the spittlebug Lepyronia coleopterata (L.) (Hemiptera: Cercopoidea)

The alimentary canal of the spittlebug Lepyronia coleopterata (L.) differentiates into esophagus, filter chamber, midgut (conical segment, tubular midgut), and hindgut (ileum, rectum). The filter chamber is composed of the anterior extremity of the midgut, posterior extremity of the midgut, proximal Malpighian tubules, and proximal ileum; it is externally enveloped by a thin cellular sheath and thick muscle layers. The sac-like anterior extremity of the midgut is coiled around by the posterior extremity of the midgut and proximal Malpighian tubules. The tubular midgut is subdivided into an anterior tubular midgut, mid-midgut, posterior tubular midgut, and distal tubular midgut. Four Malpighian tubules run alongside the ileum, and each terminates in a rod closely attached to the rectum. Ultrastructurally, the esophagus is lined with a cuticle and enveloped by circular muscles; its cytoplasm contains virus-like fine granules of high electron-density. The anterior extremity of the midgut consists of two cellular types: (1) thin epithelia with well-developed and regularly arranged microvilli, and (2) large cuboidal cells with short and sparse microvilli. Cells of the posterior extremity of the midgut have regularly arranged microvilli and shallow basal infoldings devoid of mitochondria. Cells of the proximal Malpighian tubule possess concentric granules of different electron-density. The internal proximal ileum lined with a cuticle facing the lumen and contains secretory vesicles in its cytoplasm. Dense and long microvilli at the apical border of the conical segment cells are coated with abundant electron-dense fine granules. Cells of the anterior tubular midgut contain spherical secretory granules, oval secretory vesicles of different size, and autophagic vacuoles. Ferritin-like granules exist in the mid-midgut cells. The posterior tubular midgut consists of two cellular types: 1) cells with shallow and bulb-shaped basal infoldings containing numerous mitochondria, homocentric secretory granules, and fine electron-dense granules, and 2) cells with well-developed basal infoldings and regularly-arranged apical microvilli containing vesicles filled with fine granular materials. Cells of the distal tubular midgut are similar to those of the conical segment, but lack electron-dense fine granules coating the microvilli apex. Filamentous materials coat the microvilli of the conical segment, anterior and posterior extremities of the midgut, which are possibly the perimicrovillar membrane closely related to the nutrient absorption. The lumen of the hindgut is lined with a cuticle, beneath which are cells with poorly-developed infoldings possessing numerous mitochondria. Single-membraned or double-membraned microorganisms exist in the anterior and posterior extremities of the midgut, proximal Malpighian tubule and ileum; these are probably symbiotic.

Establishing a new rat model of central venous sinus thrombosis and analyzing its pathophysiological and apoptotic changes

This study aims to establish a new animal model of cerebral venous sinus thrombosis (CVST) and to investigate the pathophysiological and apoptotic changes of CVST.Fifty-eight adult Sprague–Dawley rats were used in the present study. They were randomized into three groups, namely control (n=6), embolism (n=26) and sham-operated (n=26) groups. In the embolism group, a self-made plastic graft was inserted in the superior sagittal sinus of each rat during the operation. Each plastic graft had a total length of 0.4cm, its conical anterior segment had the largest diameter of 0.12cm and its posterior segment became gradually thin and flat with a width of 0.2cm and length of 0.1cm. In both the embolism and the sham-operation groups, the rat brains were resected at 6h, 1, 3, and 5 days post-surgery. Gross observation and water content of samples were assessed. Immunohistochemistry for caspase 3, Bcl-2 and Bax were also performed.In the embolism group, cerebral edema reached a peak level at 6h after surgery and then gradually recovered. Significant elevated positive rates of caspase 3, Bcl-2 and Bax after embolism operation were observed, reaching peaks at 1 day time point. Yet, Bcl-2/Bax decrease significantly during the follow-up, indicating apoptosis induction in embolism operation group.The new rat CVST model made by inserting a solid graft into the superior sagittal sinus is reproducible and reliable. Apoptosis plays a crucial role during the development of CVST pathophysiology.

Numerical and experimental study on liquid-solid flow in a hydrocyclone

Hydrocyclones are widely used in industry, of which the geometrical design using CFD techniques is gaining more popularity in recent years. In this study, the Euler-Euler approach and the Reynolds stress model are applied to simulate the liquid-solid flowfield in a hydrocyclone. The methodology is validated by a good agreement between experimental data and numerical results. Within the research range, the simulation indicates that the liquid-solid separation mainly occurs in the conical segment, and increasing conical height or decreasing cylindrical height helps to improve the grade efficiencies of solid particles. Based on these results, two of the same hydrocyclones are designed and installed in series to establish a liquid-solid separation system. Many experiments are then conducted under different conditions, in which the effects of the water cut and the second hydrocyclone on the separation are investigated. The results also confirm that smaller solid particles are more susceptible to the inlet conditions, and the second hydrocyclone plays a more important role as the water cut reduces.

Aerodynamic performances of hypersonic aircrafts with surface mass transfer

The results of investigations related to aerodynamic performances of a high-speed aircraft model, the body of which is designed in the form of rotary solids consisting of different combinations of conical bodies, for example, with permeable conical blunt-nosed body, if there is an active thermal protection, central cylindrical or poorly conical segment and with conical tailplane have been presented in the work. The profiles of pressure distribution over the body’s surface under different angles of attack have been obtained. These profiles make it possible to obtain information about the dynamic performance of the aircraft and reactive drag.

Equivalent mechanical model for seismic forces in combined tanks subjected to vertical earthquake excitation

Liquid-storage tanks with circular cross sections are commonly built with a combined vessel consisting of a truncated cone and a superimposed top cylindrical cap. Unlike cylindrical tanks, combined tanks are characterized by the inclination of the walls of the conical segment. As a result, compressive meridional stresses are induced in the shell by the hydrostatic pressure of the contained fluid and the hydrodynamic pressure associated with vertical ground excitation. The current paper aims at identifying the dynamic characteristics of liquid-filled combined tanks subjected to vertical ground excitation. Numerical analysis is conducted based on a coupled finite-boundary element formulation that accounts for the associated fluid–structure interaction. An equivalent model is developed to duplicate forces induced in liquid-filled combined vessels subjected to vertical base excitation. The proposed model accounts for the flexibility of the vessel walls. Meanwhile, the contained fluid is idealized as rigid and flexible components. The proposed equivalent model provides a simplified tool to predict seismically-induced forces in liquid-filled vessels subjected to vertical earthquake excitation.

A STABLE DESIGN OF COAXIAL ADAPTOR FOR RADIAL LINE SLOT ANTENNA

A new design of feed for radial line slot antenna (RLSA) is presented. For better impedance match to the waveguide the effect of the various feed parameters is analyzed and their design sensitivity is studied. This paper emphasizes the advantages of using feed with a funnel below the connector entry and a conical segment over the entering probe.

A New Soldier-Producing Aphid Species,Pseudoregma baenzigeri,sp. nov., from Northern Thailand

Pseudoregma baenzigeri, sp. nov., is described from northern Thailand. This species forms dense, huge colonies on shoots of the bamboo Dendrocalamus sp., and produces many first-instar, pseudoscorpion-like soldiers. Alate sexuparae were found from the end of September to mid October. Two syrphids, Eupeodes sp. A (allied to E. confrater) and Dideoides chrysotoxoides, and the pyralid Dipha aphidivora were recorded as predators of P. baenzigeri. The aphids were also likely to be eaten by some rodents. The apterous adult, nymphs, soldier and alate sexupara of P. baenzigeri can be distinguished from those of the other congeners by the longer, conical ultimate rostral segment. A tentative key to the species of Pseudoregma living on bamboo is provided.

Damage Tolerance of Large Shell Structures

Progressive damage and fracture of large shell structures is investigated. A computer model is used for the assessment of structural response, progressive fracture resistance, and defect/damage tolerance characteristics. Critical locations of a stiffened conical shell segment are identified. Defective and defect-free computer models are simulated to evaluate structural damage/defect tolerance. Safe pressurization levels are assessed for the retention of structural integrity at the presence of damage/defects. Damage initiation, growth, accumulation, and propagation to fracture are included in the simulations. Damage propagation and burst pressures for defective and defect-free shells are compared to evaluate damage tolerance. Design implications with regard to defect and damage tolerance of a large steel pressure vessel are examined.

Analysis of fluted conical shell roofs using the finite-element method

The finite-element method is used to obtain an elastic linear analysis of a fluted shell roof. A finite element in the form of a conical segment is developed. The element's displacement fields are in terms of curvilinear coordinates, satisfy the exact requirement of rigid body modes of deformation and has six degrees of freedom at each of the four corner nodes. The roof is made up of several conical segments joined together along lines of generators. To satisfy equilibrium and compatibility along these junctions and to reduce computational time the stiffness matrix for any element next to these lines is developed in a special way. The coordinates of the nodes along these lines are transformed into a global coordinate system while leaving the other nodes of these elements to have their original curvilinear directions. The results are compared with a finite-difference solution and a parametric study is carried out to find the effect of varying the geometry of the roof on the level of deflections and stresses.

Impulse responses and effective lengths for brass instruments

A brass instrument has three major parts: an input segment, a cylindrical or conical central segment, and a bell. (The latter two are often treated together.) It is conceptually useful to isolate the input segment from the rest of the air column and study the acoustical behavior of that complete segment rather than its components. Features in time- and frequency-domain plots can be correlated very easily with each other and with the physical structure. Combining the input segment’s time-domain behavior with that for the rest of the air column yields some novel impulse responses for use with any model of the lip reed [R. D. Ayers, J. Acoust. Soc. Am. 100, 1190–1198 (1996)]. In the frequency domain, effective lengths for the input segment and the rest of the air column can be combined to give a useful indicator for the degree of harmonic alignment among the input impedance peaks [R. D. Ayers, J. Acoust. Soc. Am. 98, 81–87 (1995)]. Specific examples in both domains will be discussed.

On Some Coupled Quasi-fixed Points Theorems

Some existence theorems are known for coupled quasi-fixed points of nonlinear mixed monotone operators from ak-fold conical segment [u0,v0] into a real Banach space, wherek=1 or 2. In this note, we extend those results to an arbitrary but finitekby a simple but nontrivial iterative mechanism. Interestingly enough, for mixed monotone operators withk≥3 folds, the Lipschitz condition ensuring the uniqueness of their fixed points is as simple as the cases ofk≤2.

Helicon waves in a flaring magnetic field

Helicon wave (whistler waves bounded transversely by a magnetic field surface) propagation is investigated for a cylindrically symmetric curved (flaring) boundary using a finite-element method where the propagation region is divided into a sequence of truncated cones. In each conical segment, a local spherical coordinate system is used with the origin at the apex of the cone. A vector wave equation for the fields is formulated for a cold plasma and reduced, in spherical coordinates, to a pair of coupled partial differential equations (PDEs) for two scalar functions. The PDEs are separable for the azimuthal eigenvalue m = 0. The -dependence is a Legendre function, with non-integer eigenvalues determined by the cone angle. The dependence on the radial coordinate, x, satisfies a fourth-order ordinary differential equation (ODE). A straightforward numerical integration of the equation from to fails for large values of , because of the existence of an exponentially growing solution to the equation. Consequently, a different approach is needed. Four independent solutions, valid for , in the form of power series in x (PS) are obtained which are each asymptotically proportional to as . For x large, four asymptotic expansions (AE) are obtained in the form of series in 1/x times or . The problem then is to find four linear combinations of the four PSs, each of which approaches one of the AEs in the limit by first deriving a double-integral representation of each PS, valid for all x, and then using its limit to match each AE to a linear combination of the PSs. For special values of or 4N, N an integer) closed-form solutions (polynomials times exponentials) result that are exact representations of the solution for all x. Solutions are computed and illustrated for an outgoing wave using the closed-form solution for special values of , and as a function of and x using the PS and AE, which have a large range of overlap. The propagating solutions of the ODE are also obtained using a WKB method and are used to calculate the propagation in a slowly diverging parabola of revolution.

Ultrastructure of the digestive system of the Le fhopper Euscelidius variegatus Kirshbaum (Homoptera : Cicadellidae), with and without congenital bacterial infections

In the digestive system of Euscelidius variegatus Kirshbaum (Homoptera : (Cicadellidae), the close apposition of the anterior midgut with its posterior tabular midgut forms a filter chamber, which shunts excess water in the imbibed plant sap to the hindgut. Leafhoppers congenitally infected with a parasitic enteroform bacterium (designated BEV) had slightly atrophied digestive systems. There were numerous bacteria within the cells of the filter chamber, conical segment, and tubular midgut. Bacteria within the epithelium cells were usually enclosed within lysosomes. Epithelium cells swollen with large numbers of bacteria, had deteriorated cell membranes, and bacteria had erupted into the gut lumen. Leafhoppers not infected by BEV, harbored bacteria in the gut lumen, but not intracellularly within gut cells.

Head-loss reduction in the water-intakes/outlets of pumped-storage tower (shaft)-type power plants

1. The installation of a conical transitional segment between a tower (shaft)-type water intake-outlet and penstock affects a significant reduction in head loss in the pump mode, but has virtually no effect on the magnitude of the latter in the pump mode. 2. The existence of a conical transitional element in the pump mode appreciably lowers the discharge velocities of the flow and increases the effective height of the water-passing openings by 1.5–1.7 times when the height of the intake openings h≥0.5dp. 3. The head losses in the intake-outlet decrease in the pump mode of operation with increasing degree of expansion of the transitional diffusor segment.

Fixed point results in ordered normed spaces with applications to abstract and differential equations

In [S] fixed point results are derived for an increasing operator A: [u, U] -+ [u, 01, where [u, u] is a conical segment in an ordered Banach space with normal order cone P. As the main results, an existence a fixed point of A is proved by assuming that A( [u, u]) is weakly relatively compact and separable. If P is also minihedral, then A is shown to have least and greatest fixed points. No continuity or linearity hypotheses are imposed on A. In this paper we shall show, for instance, that if [u, u] is a conical segment in an ordered normed space E, and if A: [u, u] + [u, u] is increasing and weakly relatively order compact, then A has the least and the greatest fixed point, provided that the order cone of E is normal or A( [u, u]) is separable. Moreover, these fixed points are constructed by countable iteration processes. The so obtained fixed point results are then applied to derive results on existence of extremal or unique solutions of the operator equation