Triangular Bar Research Articles

A cosmic ray muons tomography system with triangular bar plastic scintillator detectors and improved 3D image reconstruction algorithm: A simulation study

PurposeMuons are characterized by a strong penetrating ability and can travel through thousands of meters of rock, making them ideal to image large volumes and substances typically impenetrable to, for example, electrons and photons. The feasibility of 3D image reconstruction and material identification based on a cosmic ray muons tomography (MT) system with triangular bar plastic scintillator detectors has been verified in this paper. Our prototype shows potential application value and the authors wish to apply this prototype system to 3D imaging. In addition, an MT experiment with the same detector system is also in progress. MethodsA simulation based on GEANT4 was developed to study cosmic ray muons' physical processes and motion trails. The yield and transportation of optical photons scintillated in each triangular bar of the detector system were reproduced. An image reconstruction algorithm and correction method based on muon scattering, which differs from the conventional PoCA algorithm, has been developed based on simulation data and verified by experimental data. ResultsAccording to the simulation result, the detector system’s position resolution is below 1 ∼ mm in simulation and 2 mm in the experiment. A relatively legible 3D image of lead bricks in size of 20 cm × 5 cm × 10 cm used our inversion algorithm can be presented below 1× 104 effective events, which takes 16 h of acquisition time experimentally. ConclusionThe proposed method is a potential candidate to monitor the cosmic ray MT accurately. Monte Carlo simulations have been performed to discuss the application of the detector and the simulation results have indicated that the detector can be used in cosmic ray MT. The cosmic ray MT experiment is currently underway. Furthermore, the proposal also has the potential to scan the earth, buildings, and other structures of interest including for instance computerized imaging in an archaeological framework.

Anti-galling β-SiC coating dies for fine cold forging of titanium

β-SiC coating die and punch were employed for forging of titanium wire to triangular bar in high reduction of thickness by 35 %. CNC (computer numerical control) stamper was utilized to describe the elasto-plastic behavior of titanium wire in dry forging. Precise analyses on the contact interface between SiC coating and titanium work were made to investigate the mass transfer of metallic titanium as well as titanium oxide debris particles onto SiC coating surface. In particular, element mapping and Raman spectroscopic analyses were performed to describe the formation of thin titanium oxide film as well as the agglomeration of unbound carbon on the SiC coating punch.

EXTENDED BOUSSINESQ EQUATIONS FOR WAVES IN TWO POROUS LAYERS

In this study we continue the work of Vu et al. (2018) [Coastal Eng. 139, 85-97] to develop an extended Boussinesq model that predicts the propagation of water waves in two porous layers. The first and second layer can be a water layer or a porous layer. The inertial and drag resistances are considered in the developed model. After being successfully validated against the analytical solutions, the model is used to simulate waves propagating over a submerged triangular porous bar. The numerical results show good agreement with the physical experimental data of Hsiao et al. (1998) [Proc. Royal Society of London A 458, 1291-1322].

Moisture Sorption and Desorption in Epoxy Composites Reinforced with Triangular and V-Shaped Bars: Determination of Diffusion Coefficient and Effect of Varied Factors

Sorption and desorption of moisture in epoxy composites reinforced with triangular and V-shaped bar fillers were studied. Epoxy was reinforced with vinyl ester bar assemblies fabricated according to 4 varied factors: bar orientation relative to diffusion direction (pointed or base side), bar alignment (parallel or staggered), spacing between bars (1 or 5 mm), and bar cross-sectional shape (triangular or V-shaped). Unlike previous studies, the bar fillers were initially coated with small amount of epoxy resin to improve wetting during fabrication of composites. Moisture uptake and loss of composites during one-side exposure to water vapor (50% relative humidity at 60°C) and hot air (60°C), respectively, were monitored with time. Experimental results show weight change of composites during moisture sorption and desorption varies linearly with square root of exposure time. Diffusion coefficients of composites were determined by assuming the material to be semi-infinite and fitting a mathematical solution to Fick’s second law of diffusion to weight change data. Results show diffusion coefficient of composites during moisture sorption is increased when bars are oriented pointed relative to diffusion direction, aligned parallel, spaced at 1 mm, and has triangular cross-sectional shape. However, during desorption, the diffusion coefficient is increased when base side of bars are exposed and when the bars are aligned staggered. The observed effects of factors on moisture diffusion coefficients of epoxy composites during sorption and desorption are discussed in relation to path length, available diffusion area, and status of epoxy/vinyl ester interphase before and after moisture sorption in composites.

Desorption Behavior of Epoxy/Amine-Coated Polyester Triangular Bar Composites Pre-Exposed to Acid Environment

Epoxy/amine-coated polyester triangular bar composites were fabricated and exposed to 5 wt% hydrochloric acid (HCl) solution at 40 °C. The weight loss characteristics of pre-exposed composites in heated air at 40 °C under forced convection were studied as function of size, spacing, alignment, and orientation of triangular bars. The diffusion coefficient of composites during desorption increases when the bars are oriented flat and are aligned in parallel. The same result is observed when the size of triangular bars is increased, and when spacing between bars is decreased. These results are attributed to the presence of epoxy/polyester interphase regions, which are more accessible when the triangular bars are oriented flat and aligned parallel, have larger size, and have smaller spacing. These interphase regions are preferred conduits of water during desorption of composites. The diffusion coefficients of composites being higher than the values of epoxy and polyester resins further confirm the effect of interphase regions. Among the factors, orientation of triangular bars has the highest influence on the desorption behavior of epoxy composites.

Quantum-Inspired Evolutionary Algorithm for Topology Optimization of Modular Cabled-Trusses

This article proposes an alternative optimization framework applied to topology optimization of modular lightweight cabled-truss structures. These structures are described as a system of intrinsically positioned cables and triangular bar formations jointed at their ends by hinged connections to form a rigid framework. The optimized topologies are determined through a stochastic discrete optimization procedure that uses ground structure approach, nonlinear finite element analysis, and quantum-inspired evolutionary algorithms. The optimization searches for optimal mass reduction with minimal losses in stiffness, such relation, is expressed by the stiffness-to-mass ratio parameter. Nonlinear finite element analysis is used to evaluate the static structural response. In order to decrease computation time, kinematically instable and structurally invalid individuals are filtered before evaluation. Modular design approach is taken into consideration to reduce the number of design variables and increase the productibility of cabled-trusses. Symmetric structural response is desired since in several mechanical applications forces can assume different directions during the working cycle. A modular ground structure with 300 elements is optimized, and optimal truss and cabled-truss topologies are compared. Complementary analyses comprise the investigation of the structural performance under different number of modules and slenderness ratios. The results indicate that the proposed optimization framework leads to optimized structures. In addition, it was observed that cabled trusses presented significant improvements in structural performance when compared with trusses.

Generalized complex variable boundary integral equation for stress fields and torsional rigidity in torsion problems

Theory of complex variables is a very powerful mathematical technique for solving two-dimensional problems satisfying the Laplace equation. On the basis of the conventional Cauchy integral formula, the conventional complex variable boundary integral equation (CVBIE) can be constructed. The limitation is that the conventional CVBIE is only suitable for holomorphic (analytic) functions, however. To solve for a complex-valued harmonic-function pair without satisfying the Cauchy–Riemann equations, we propose a new boundary element method (BEM) based on the general Cauchy integral formula. The general Cauchy integral formula is derived by using the Borel–Pompeiu formula. The difference between the present CVBIE and the conventional CVBIE is that the former one has two boundary integrals instead of only one boundary integral in the latter one. When the unknown field is a holomorphic function, the present CVBIE can be reduced to the conventional CVBIE. Therefore, the conventional Cauchy integral formula can be viewed as a special case applicable to a holomorphic function. To examine the present CVBIE, we consider several torsion problems in this paper since the two shear stress fields satisfy the Laplace equation but do not satisfy the Cauchy–Riemann equations. Using the present CVBIE, we can directly solve the stress fields and the torsional rigidity simultaneously. Finally, several examples, including a circular bar containing an eccentric inclusion (with dissimilar materials) or hole, a circular bar, elliptical bar, equilateral triangular bar, rectangular bar, asteroid bar and circular bar with keyway, were demonstrated to check the validity of the present method.

Hybrid optimization of cabled-trusses: Benchmarks for mechanical engineering

This paper proposes cabled-trusses benchmarks for mechanical engineering applications and provides suitable tools for modeling and optimization of cabled-trusses. These structures correspond to a system of cables and triangular bar formations jointed at their ends by hinged connections to form a rigid framework. The optimized cabled-truss is determined through a discrete optimization procedure that uses nonlinear finite element analysis, genetic algorithm, and fuzzy logic. In this work, planar and spatial trusses and cabled-trusses are optimized to achieve minimum weight designs. Also, the structural performance of the optimized structures is compared. In summary, the results show that cabled-trusses feature improvements over trusses.

Stress wave analysis of thermo-piezoelectric solid bar of polygonal cross-sections immersed in fluid

Purpose – The purpose of this paper is to study the problem of wave propagation in an infinite, homogeneous, transversely isotropic thermo-piezoelectric solid bar of polygonal (triangle, square, pentagon and hexagon) cross-section immersed in fluid is using Fourier expansion collocation method, with in the frame work of linearized, three-dimensional theory of thermo-piezoelectricity. Design/methodology/approach – A mathematical model is developed to study the wave propagation in an infinite, homogeneous, transversely isotropic thermo-piezoelectric solid bar of polygonal cross-sections immersed in fluid is studied using the three-dimensional theory of elasticity. Three displacement potential functions are introduced, to uncouple the equations of motion and the heat and electric conductions. The frequency equations are obtained for longitudinal and flexural (symmetric and antisymmetric) modes of vibration and are studied numerically for triangular, square, pentagonal and hexagonal cross-sectional bar immersed in fluid. Since the boundary is irregular in shape; it is difficult to satisfy the boundary conditions along the curved surface of the polygonal bar directly. Hence, the Fourier expansion collocation method is applied along the boundary to satisfy the boundary conditions. The roots of the frequency equations are obtained by using the secant method, applicable for complex roots. Findings – From the literature survey, it is clear that the free vibration of an infinite, homogeneous, transversely isotropic thermo-piezoelectric solid bar of polygonal cross-sectional bar immersed in fluid have not been analyzed by any of the researchers, also the previous investigations in the vibration problems of transversely isotropic thermo-piezoelectric solid bar of circular cross-sections only. So, in this paper, the wave propagation in thermo-piezoelectric cylindrical bar of polygonal cross-sections immersed in fluid are studied using the Fourier expansion collocation method. The computed non-dimensional frequencies are plotted in the form of dispersion curves and its characteristics are discussed, also a comparison is made between non-dimensional wave numbers for longitudinal and flexural modes piezoelectric, thermo-piezoelectric and thermo-piezoelectric polygonal cross-sectional bars immersed in fluid. Research limitations/implications – Wave propagation in an infinite, homogeneous, transversely isotropic thermo-piezoelectric solid bar of polygonal cross-sectional bar immersed in fluid have not been analyzed by any of the researchers, also the previous investigations in the vibration problems of transversely isotropic thermo-piezoelectric solid bar of circular cross-sections only. So, in this paper, the wave propagation in thermo-piezoelectric cylindrical bar of polygonal cross-sections immersed in fluid are studied using the Fourier expansion collocation method. The computed non-dimensional frequencies are plotted in the form of dispersion curves and its characteristics are discussed, also a comparison is made between non-dimensional wave numbers for longitudinal and flexural modes of piezoelectric, thermo-piezoelectric and thermo-piezoelectric polygonal cross-sectional bars immersed in fluid. Originality/value – The researchers have discussed the wave propagation in thermo-piezoelectric circular cylinders using three-dimensional theory of thermo-piezoelectricity, but, the researchers did not analyzed the wave propagation in an arbitrary/polygonal cross-sectional bar immersed in fluid. So, the author has studied the free vibration analysis of thermo-piezoelectric polygonal (triangle, square, pentagon and hexagon) cross-sectional bar immersed in fluid using three-dimensional theory elasticity. The problem may be extended to any kinds of cross-sections by using the proper geometrical relations.

Collaborative study for quantification of Anisakis larvae in spiked salmon fillets (Salmo salar) by a modified Codex digestion method

A collaborative study for quantification of Anisakis larvae in spiked farmed salmon fillets was conducted by 12 laboratories in 2012, using a modified Codex method (CODEX STAN 244). N = 6 samples with a different number of Anisakis larvae including two blind duplicates were analyzed by participants. All laboratories applied the same modified digestion method with stirring speed of 500–600 rpm, using a triangular stirring bar and a maximum digestion temperature of 35 °C in order to reduce fragmentation of larvae. All participants found correctly no larvae in the control samples while the mean recovery rate of all spiked larvae was 86.6 %. The among-laboratory reproducibility was 16.5 %. Differences were noticed in the interpretation of Anisakis fragments, which occurred as a result of prolonged frozen storage of the samples.

Hybrid fuzzy-genetic system for optimising cabled-truss structures

This paper demonstrates an application of a hybrid fuzzy-genetic system in the optimisation of lightweight cabled-truss structures. These structures are described as a system of cables and triangular bar formations jointed at their ends by hinged connections to form a rigid framework. The optimised lightweight structure is determined through a stochastic discrete topology and sizing optimisation procedure that uses ground structure approach, nonlinear finite element analysis, genetic algorithm, and fuzzy logic. The latter is used to include expertise into the evolutionary search with the aim of filtering individuals with low survival possibility, thereby decreasing the total number of evaluations. This is desired because cables, which are inherently nonlinear elements, demand the use of iterative procedures for computing the structural response. Such procedures are computationally costly since the stiffness matrix is evaluated in each iteration until the structure is in equilibrium. Initially, the proposed system is applied to truss benchmarks. Next, the use of cables is investigated and the system’s performance is compared against genetic algorithms. The results indicate that the hybrid system considerably decreased the number of evaluations over genetic algorithms. Also, cabled-trusses showed a significant improvement in structural mass minimisation when compared with trusses.

Investigation of optimal position of a vortex generator in a blocked channel for heat transfer enhancement of electronic chips

A heat transfer optimization of a channel including three blocks attached to its bottom wall (i.e. electronic chips) with an inserted triangular bar acting as a vortex generator (control element) is carried out in order to maximize heat transfer rate as well as to achieve heat flux uniformity over the blocks. Genetic algorithm (GA) combined with Gaussian Process (GP) is utilized as the optimization algorithm. The Nusselt number of the samples is computed with the aid of a Navier–Stokes solver. It is shown that a well trained GP can accurately predict the Nusselt number of each block separately which matches very well with data obtained from the outputs of Navier–Stokes solver. The fitness function is defined as the summation of weighted Nusselt numbers and standard deviation term multiplied by a constant coefficient (to control the priority of homogeneity). The optimization results show that the greater value of the standard deviation multiplier, the more uniform Nusselt numbers. In addition, the optimum location of vortex generator is seen to be above the first block for which uniformity is neglected; however, it displaces from top of the first block to the top of the second block as uniformity become more important. Another conclusion obtained in the present work is that the optimal position of the vortex generator is independent of the Reynolds number.

Control of heat transfer and fluid flow using a triangular bar in heated blocks located in a channel

Control of laminar, two-dimensional, steady forced convection heat transfer and fluid flow in an isothermally heated blocks located in a channel was analyzed numerically. The channel had three blocks attached on its bottom wall. The cooling air entered the channel with uniform velocity. A triangular cross-sectional bar was used as a control element. Both the top wall of the channel and the bar were isothermal. The bar was located in two different points in the y-direction and these parameters were tested at three different Reynolds numbers ranging between (400 ≤ Re ≤ 1300). Results were also compared for no triangle case. It was obtained that insertion of a triangular cross-sectional bar enhanced the heat transfer for all Reynolds numbers and the best heat transfer was observed for the position of the bar with y = 3.5.

Réflexion sur les ouvrages

ABSTRACT Reflection of water waves on maritime structures is an important problem of coastal engineering. Classic reflection conditions on structures require the knowledge of an angle of incidence that is a priori unknown. In order to get rid of it, we develop a horizontal dissipative model for water waves. Dissipation is assessed from the propagation of wave in a bilayer composed of a layer of fluid covering a porous bed. The model is tested on a triangular porous bar and a rubble mound breakwater.

Dynamic problems for an elastic triangular bar under plane deformation

Dynamic problems for an elastic triangular bar under plane deformation

Torsional Characteristics of Hemp Palm Branch with Triangular Cross-Section. 2-Layerd Composite Bar.

The cross section of main frame structure is preferable to be a cylinder for plants and animals in order to adapt to their environment. There are some exceptionals. One of those is a hemp palm branch. It has an up side-down isosceles triangular shape. Since the hemp palm branch has unusually large leaves and a relatively slender branch stem as compared with other trees, the branches must be subjected a large twisting moment. A triangular cross section reinfored by a functionally graded distribution of fibers must be a solution for that problem, which can reduce the induced stress. This paper presents a torsional analysis of a triangular bar based on the 2-layerd model. Deriving an analytic solution using conformal mapping and complex warping function, the stress distributions and torque were computed. The two layerd bar reduced the maximum shear stress as compared with the one of a homogeneous bar.

Modulation of Rectangular and Triangular Bar targets by Optical Systems using Hamming Filters

The modulation in incoherent imaging systems for rectangular and triangular bar targets has been investigated using Harming apodisation filters. The results of contrast Md cutoff frequency responses have been reported with the help of certain profiles. Different apodisation parameters with different values have been used for the calculation of image modulation.

Gyrodactylus gemini n. sp. (Monogenea: Gyrodactylidae), a parasite of Semaprochilodus taeniurus (Steindachner) from the Venezuelan Amazon

Gyrodactylus gemini n. sp. (Monogenea, Gyrodactylidae) is described from the surface of the body and fins of the fish Semaprochilodus taeniurus (Steindachner) imported into Britain from the Venezuelan Amazon. The new species differs from other species of the genus, including those described from South and Central America, by having: (i) stout hamuli with straight shafts and diverging roots; (ii) marginal hooks with the sickle length larger than the width; (iii) a dorsal bar without a medial constriction; (iv) a rectangular ventral bar with short processes; (v) a triangular ventral bar membrane; and, most obviously, (vi) at least two generations which can develop two embryos simultaneously. This is the first known species of the genus Gyrodactylus from the Venezuelan Amazon and the first record of the subgenus Gyrodactylus (Gyrodactylus) from South America.

Testing abrasive wear in mineral comminution

The abrasive wear properties of materials in sliding and impact contact with solid mineral particles during the comminution process have been studied with two experimental techniques. The equipment used has a wide pressure and velocity range, and can be used to simulate the triboconditions inside pulverizers. Using the experimental apparatus, a number of different materials have been tested and classified according to their resistance to abrasive wear in rubbing contact with particulate coal. The investigation was divided into two parts. In each part the different shape of grinding bar (tested material) was used in order to focus attention on the different wear phenomena. Tests with triangular bar can provide useful information about wear properties of various materials. Apart from the maximum wear resistance, MWR, the initial drop of wear resistance, IDWR, can be determined. The value of IDWR gives information about the contribution of the brittle fracture of the sharp edges and asperities to the local wear of the bar. A comparison between industrial data and simulated tribo-testing results shows a very good correlation. This proved that the results from relatively simple rigs may be used in predicting the service life of the machine elements.

Dispersion of elastic waves in a triangular bar

It is shown that in a bar with an equilateral triangular cross-section longitudinal, torsional, and bending modes of wave propagation are possible. The first few branches of the dispersion curves for each of these modes have been calculated using the collocation method. The first branch of the longitudinal mode shows excellent agreement with experiment. The existence of an “end-resonance” is inferred from the experimental results.