Increase In Length Ratio Research Articles

Transcriptomic Responses and Larval-Stage Growth of Protandrous Yellowfin Seabream (Acanthopagrus Latus) to Different Polyethylene Microplastics Exposure.

Polyethylene microplastics (PE-MPs) were widespread in the marine environment; thus, their influences on marine hermaphroditic fish cannot be ignored. This study intends to evaluate the adverse biological effects of two different sources of PE, identified by Raman spectroscopy, on protandrous yellowfin seabream (Acanthopagrus latus) larvae. Growth retardation, brain lesions, head/body length ratio increase, and neuroendocrine system disorders were found, and growth and neuroendocrine regulation-related genes such as sstr2, ghrb, irs1, UGT2B15, UGT2C1, drd4a, esr2b, hsd3b7, and hsd17b2 were identified. PE microbeads (100 μm) showed more severe tissue damage on fish, while environmental PE fibers (500-2500 μm) showed more imperceptible adverse effects. There were 218 DEGs up-regulated and 147 DEGs down-regulated in the environmental PE group, while 1284 (up) and 1267 (down) DEGs were identified in the virgin PE group. PE-MP stress influenced physiological processes like growth and neuroendocrine regulation and cholesterol-steroid metabolism, and caused tissue damage in the fish larvae. The study highlights the effects of environmental PE exposure on hermaphroditic protandrous fish.

Numerical simulation and experimental study on the compression performance of a double layer cross-lattice-core sandwich structure

Lattice sandwich structures are widely used in many engineering fields for their excellent mechanical properties, such as aerospace, transportation, construction and so on. In this paper, a new type of double layer cross-lattice-core sandwich structure is proposed. Firstly, based on the nonlinear finite element software ABAQUS, a finite element numerical simulation analysis is processed to the sandwich structure unite cell under flat compression. The deflection pattern, load-displacement curve and internal energy-displacement curve are obtained to discuss the compression performance of the unite cell with some specific geometric parameters, such as arm length ratio, clamped angle and thickness of the cross-lattice-core. It is found that the compression performance of the lattice sandwich structure with an arm length ratio of 1 and an included angle of 90° is optimal. The energy absorption effect decreases slightly with the increases of the arm length ratio increases, which will be greatly reduced when the core angle is lower than 90°. Then the unite cell model of the structure is prepared using 3D printing technology, and its compression performance is investigated by flat compression tests and verified in comparison with the numerical analysis results. Finally, the load-bearing property of the structure is further verified by compression analysis of a plate structure consisting of several unite cells. The results provide a reference for the design and engineering application of the structure.

Characterization of the tree length structure of the Nectarine tree before flowering by metric measurements in Sefrou, Morocco

This study aims to describe the architecture of Nectarine fruit trees located in Sefrou region. This characterization concerned the length variation of all the tree structure before flowering by metric exhaustive and non-destructive measurements. The study conducted on Nectarine variety of Spring Bright, by measuring 10 trunk, 40 frames, 157 1st underframe, 280 2nd underframe, 361 3rd underframe, 308 4th underframe, 134 5th underframe and 1250 of mixed branches, that have been labelled and numbered. The characterization of the tree revealed the underlying logic of the plant’s construction, The lengths, decrease from scaffold to 5th level under frame but it experiences a 357% increase in length ratio for the mixed branch due to its role as the primary fructification structure. This type of distribution is logic for the goblet training pruning program. The mean number of structure evolution was (scaffold) 4/(1st level) 4/(2nd level)1/3rd level 2/(mixt branch) 9 . The raw length data was not homogeneous probably due to the pruning effect, so they were grouped in three to four class to enhance the homogeneity.

Computational study to predict the thermal performance and optimal design parameters of a T-shaped fin subjected to natural convection

The present paper aims to predict the optimal design parameters of a T-shaped fin subjected to natural convection using constructal theory. Both analytical and computational investigations are performed to determine its thermal performance for a wide range of thermo-physical and geometric parameters. Power law type temperature-dependent heat transfer coefficient is assumed for natural convection. For analytical solution Adomian decomposition method is adopted to evaluate the temperature distribution in both the stem and flange part of the fin. A numerical scheme called finite difference method is implemented to validate the analytical results. The temperature distribution obtained from the computational analysis using ANSYS FLUENT 14.0 is lower than that obtained from the analytical calculations. Moreover, the actual heat transfer rate is also compared between the two methods which reveal that the computational analysis gives higher value as compared to the analytical results. Further, optimization study has also been carried out in a generalized way so that either the fin volume or the heat transfer rate can be taken as a constraint. It is found that with the increase in length ratio, the optimum effectiveness is obtained at a higher value of aspect ratio whereas the optimum efficiency is obtained at a lower value of it. Though, a decrease in thickness ratio predicts a higher value of actual dimensionless heat transfer rate.

Interaction of flange and web slenderness, overstrength factor and proposed stiffener arrangements for long links

This paper is aimed to investigate the interaction of flange and web slenderness ratio, overstrength factor and also to improve the behavior of long links. Pursuant to these goals, 150 numerical models of different long links were developed and exposed to cyclic loading protocol mandated by AISC 341. Link length ratio, flange and web slenderness and stiffener configurations are selected as parameters. The results revealed that the flange slenderness ratio can be relaxed to 0.38(E/Fy)0.5 for long links if the web slenderness ratio is <1.5 (E/Fy)0.5. The shear capacity of long links decreases as the link length ratio increases. The results of shear capacity showed the overstrength factor required by AISC 341 overestimates the shear capacity; therefore, two different equations to predict the overstrength factor for long links are proposed. The stiffener configuration recommended by AISC 341 limits the potential of long links. To mitigate this drawback, different stiffener configurations are proposed to empower the behavior of long links. Using additional one stiffener at each link ends can enhance shear strength, energy dissipation and plastic rotation capacities by 25%, 447% and 322%, respectively. When two additional stiffeners are introduced, these ratios modify to 29%, 479% and 332%. Moreover, rupture index values are utilized to verify proposed stiffener configurations further.

Numerical simulation of segmented ratio in bismuth telluride and skutterudites for waste heat recovery

The thermoelectric performance of the segmented annular thermoelectric generators with the bismuth telluride and skutterudites has been investigated. The effect of the length ratio of the hot-segment leg to total length leg on the thermoelectric performance of the segmented annular thermoelectric generators is analysed and discussed and the optimization design of the annular thermoelectric generator with bismuth telluride and skutterudites as the materials with high thermoelectric performance is obtained. The result of the thermoelectric performance with the manipulated variable of the increase of length ratio, the output power, output voltage and efficiency of the segmented annular thermoelectric generators increase at the beginning then decrease afterwards. Additionally, to compare with the single bismuth telluride and skutterudites annular thermoelectric generators, the output voltage, output power and the conversion efficiency of the segmented annular thermoelectric generators can be improved twice. Lastly, the thermoelectric performance of the segmented annular thermoelectric generators operating in the changes of the temperature. The result has proved that as the temperature increase, the thermoelectric performance of the annular thermoelectric generator will also increase. Hence, the acquired results may be given some useful applications of the bismuth telluride and skutterudites on the segmented annular thermoelectric generators for waste heat recovery.

Research on the Hole Length Ratio of Fan-Shaped Holes in Flat Plate Film Cooling

To study the influence of different hole length ratios on the flow structure and film cooling efficiency, a calculation model of fan-shaped hole was constructed and numerically studied. The effect of different hole length ratios on the cooling efficiency under different blowing ratios was compared and analyzed. The results showed that as the blowing ratio increases, the overall average efficiency of most of the hole length ratio cases first increases and then decreases. Only in the case with a cylindrical part length/total length ratio of 0.5 did the efficiency continue to increase. When the blowing ratio is small, the spanwise average efficiency of each hole length ratio case is closer, but the flow structure and efficiency distribution are quite different. For the medium blowing ratio, the overall average efficiency of the small hole length ratio case is higher, and the efficiency decreases as the hole length ratio increases. When the cylindrical part length/total length ratio is further increased to 1, the cooling efficiency region basically converges into a spanwise narrow region. For larger blowing ratio conditions, after 10D after the hole outlet, the case with a cylindrical part length/total length of 0.5 is more efficient.

High performance energy harvesting from flow-induced vibrations in trapezoidal oscillators

Flow-induced vibrations (FIVs) are of great interest in various engineering fields. Although FIVs possibly cause some undesirable response and fatigue damage, they can also be used to harvest hydraulic and wind energy. This paper investigated the effects of the attack angle (α) and length ratio (d/D) of a trapezoidal oscillator on the FIV response and energy harvesting capability. The experimental results illustrate the occurrence of a full interaction between the vortex-induced vibration (VIV) and galloping at α = 0° and α = 90°. The attack angle and length ratio greatly influence the energy harvesting. In general, a trapezoidal oscillator at α = 0° exhibits better energy harvesting than that at α = 90°. At α = 0°, the triangular oscillator gains the maximum amplitude of 0.703D with an output voltage of 10.407 V, harvested power of 24.056 mW, and harvesting efficiency of 12.151%. Nevertheless, the performance is reduced as the length ratio increases. At α = 90°, a trapezoidal oscillator with d/D = 0.5 is considered as the best one for energy harvesting. The computational fluid dynamics (CFD) analysis indicates that the displacement is highly related to the transferred energy between the oscillator and the fluid. A greater amount of transferred energy is the main cause of larger displacement, resulting in a more disordered vortex shedding. Finally, it is recommended to install a triangular oscillator at α = 0° to deliver optimal energy harvesting.

Time delay in the mixed pump two-stage cascade erbium-doped fiber

This thesis mainly focuses on the study of slow light under the mixed pump two-stage cascade erbium-doped fiber. Compared with previous studies, we adopt different pump optical fiber connections in structure and this structure can produce larger time delay. We specifically explore the relationship between modulation frequency, group velocity and time delay under different pump ratios. We find that the time delay gradually increases and the group velocity gradually decreases as the pump ratio M (M = P1480:P980) decreases. We also study length ratio and time delay at different frequencies. With the increase of length ratio N (N = L1:L2, L1 and L2 represent the length of the first and second cascaded optical fibers, respectively), the time delay all increases at different frequencies, and the time delay changes significantly at low frequencies.

Numerical evaluation on the decaying swirling flow in a multi-lobed swirl generator

Accurate predictions of decaying swirling flow behavior in the multi-lobed swirl generator (MLSG) are essential for certain engineering applications. In this study, decaying swirling flow characteristics in an MLSG are examined using the Computational Fluid Dynamics (CFD) technique with a Reynolds stress turbulence model (RSM). The effects of different lobe numbers (n) and pitch length ratios (P/D) on swirl intensity, pressure drop, friction factor coefficient, and decay rate are observed with Reynolds number from 50,000 to 125,000. Combined with the pressure loss, the efficiency of swirl induction is evaluated by introducing a swirl effectiveness (SE) evaluation criterion. The initial swirl intensity is shown to first increases and then decreases as lobe number increases. The maximum value is obtained at lobe number n = 4. The pitch length ratios P/D corresponding to the optimal SE value obtained from different lobe also differ. The optimal SE value is achieved at n = 4 and P/D = 8. The friction factor ratio f s/f p decreases as pitch length ratio increases, but the decreasing trend decelerates over time. Correlations based on the numerical predictions of friction factor ratio f s/f p and decay rate β are presented accordingly.

Numerical and experimental investigations of the sloshing modal properties of sloped-bottom tuned liquid dampers for structural vibration control

Tuned liquid dampers (TLDs) utilize the liquid sloshing to damp vibrations of civil and mechanical structures. Rectangular tank with flat-bottom has been widely used for passive structural control. A recent experimental study, on the other hand, indicates that a TLD with sloped bottom achieves better performance than its flat-bottom counterpart, considering the improved vibration mitigation and reduced liquid mass. This work investigates the sloshing modal properties (sloshing frequencies and sloshing mode shapes) of sloped-bottom TLD using finite difference method, which is validated by full-scale tests. It is observed that the sloshing mode shapes are quite different comparing the shallow-water sloped-bottom TLD with the deep-water one. To further reveal the influence of damper geometries on the sloshing modal properties of the sloped-bottom TLD, three different geometrical parameters have been considered for parametric study, e.g. the mean water level of the liquid, the slope angle, and the ratio between the horizontal projection length of the slope and the total bottom length. It is found that the sloshing eigenfrequencies increase as the mean water level increases, as the slope angle decreases and as the length ratio increases. The eigenfrequencies vary with damper geometries in a nonlinear manner, and the results from flat-bottom TLD always act as upper limit of those from sloped-bottom TLD. The developed numerical model in the present study can be used for tuning and preliminary design of structural-mounted sloped-bottom TLDs.

Experimental and analytical study of lightweight floor system built-up with cold-formed profile steel sheet and hot-rolled steel plate (CFPSS-HRSP)

The focus of the present research is to develop a reusable and recyclable lightweight floor system fabricated with cold-formed profiled steel sheet (CFPSS) and hot-rolled steel plate (HRSP) connected through bolts. This paper presents the results of eighteen medium-scale specimens fabricated with varying lengths, bolt spacings and thickness to evaluate the flexural and failure behavior under three-point bending. The proposed system was fabricated in two phases; phase I was based on single CFPSS, whereas phase II was based on double thickness by nesting two CFPSS on top of each other. The test results indicate that phase II specimens carried 50 to 80% more load than the phase I specimens. It can be noted that the decrease in experimental load ratio correlated well with the increase in length ratio for phase II specimens. However, a higher variation of up to 18% in moment capacity was observed in phase I specimens whereas the corresponding phase II specimens, showed a variation of up to 8%. Besides, it was also observed that the mode of failure for phase I and phase II specimens varied with specimen length, CFPSS thickness and spacing between the bolts in a lightweight panel system. An analytical approach was developed based on the modified form of Newmark's equation along with a theoretical approach (up to yield). The average analytical deflection closely matched with the moderate length while the shorter and longer length specimens slightly deviated from the experimental results in both the phases.

Segregation behavior of binary mixtures of cylindrical particles with different length ratios in the rotating drum

AbstractParticle shape impacts the flow behavior of granular material but this effect is still far from being fully understood. Using discrete element method, the current work explores the segregation phenomena of the binary mixtures of cylindrical particles (differing in length but with the same diameter) in the three‐dimensional rotating drum operating in the rolling regime, with each cylindrical particle fully represented by the superquadric equation. The important characteristics and the effect of length ratio on the flow dynamics of the binary mixtures are discussed. Some trends are in sync with those of binary mixtures of spherical particles. Unique to nonspherical particles is the orientation of particles, with results indicating that the cylindrical particles align their major axes perpendicular to the drum axis and this behavior becomes more significant for large particles when the length ratio increases. The length‐induced radial segregation causes the orientation of large cylindrical particles to be less uniform.

Free vibration of a fluid-conveying nanotube constructed by carbon nanotube and boron nitride nanotube

The free vibration of a fluid-conveying nanotube composed of carbon nanotube and boron nitride (BN) nanotube is studied in this paper. The nonlocal Euler-Bernoulli beam model is adopted to describe the transverse displacement of the hybrid nanotube, and the governing equation is segmented because of the material properties' change at the junction. Then the dynamic stiffness method is used to solve the governing equation, and we investigated the effects of length ratio and nonlocal parameter on the vibration behavior and stability of the fluid-conveying hybrid nanotube. It can be concluded that the instability of the nanotube is significantly dependent on the length ratio and the nonlocal parameter. The increase of length ratio or nonlocal parameter will both make the system more unstable, in particularly, the nonlocal parameter has a great effect on the second-mode divergence. And we also find that the extra support at the junction will lead a great increment to the first two order frequencies and critical flow velocity.

On shoaling of solitary waves

One of the classic analytical predictions of shoaling-wave amplification is Green’s law – the wave amplitude grows proportional to $h^{-1/4}$, where $h$ is the local water depth. Green’s law is valid for linear shallow-water waves unidirectionally propagating in a gradually varying water depth. On the other hand, conservation of mechanical energy shows that the shoaling-wave amplitude of a solitary wave grows like $a\propto h^{-1}$, if the waveform maintains its solitary-wave identity. Nonetheless, some recent laboratory and field measurements indicate that growth of long waves during shoaling is slower than what is predicted by Green’s law. Obvious missing factors in Green’s law are the nonlinearity and frequency-dispersion effects as well as wave reflection from the beach, whereas the adiabatic shoaling process does not recognize the transformation of the waveform on a beach of finite slope and length. Here we first examine this problem analytically based on the variable-coefficient perturbed Korteweg–de Vries equation. Three analytical solutions for different limits are obtained: (1) Green’s law for the linear and non-dispersive limit, (2) the slower amplitude growth rate for the linear and dispersive limit, as well as (3) nonlinear and non-dispersive limit. Then, in order to characterize the shoaling behaviours for a variety of incident wave and beach conditions, we implement a fifth-order pseudo-spectral numerical model for the full water-wave Euler theory. We found that Green’s law is not the norm but is limited to small incident-wave amplitudes when the wavelength is still small in comparison to the beach length scale. In general, the wave amplification rate during shoaling does not follow a power law. When the incident wave is finite, the shoaling amplification becomes faster than that of Green’s law when the ratio of the wavelength to the beach length is small, but becomes slower when the length ratio increases. We also found that the incident wave starts to amplify prior to its crest arriving at the beach toe due to the wave reflection. Other prominent characteristics and behaviours of solitary-wave shoaling are discussed.

The energy absorption of rectangular and slotted windowed tubes under axial crushing

In this paper, rectangular and slotted windows were introduced to thin-walled square tubes to improve the crashworthiness of tubular structures. Four one-windowed tubes, twelve three-windowed tubes and two conventional tubes were studied by quasi-static axial crushing tests and numerical simulations. Optical measurement system MatchID was employed to achieve full-field strain measurement. The results showed that the collapse modes of conventional tubes belonged to symmetric mode, while the others were irregular mode. In addition, the introduction of windows could effectively reduce the initial peak load and increase the crush force efficiency (CFE) over conventional tube. However, the SEAs of windowed tubes did not necessarily improve even though large mass reduction for windowed tubes. The initial peak load is inclined to decrease with the increase in area ratio (η, defined as the ratio between the windowed area and the surface area of conventional tube). Furthermore, it was found that cracks appeared in numerous specimens in the tests due to welding. And with the increase in length ratio (λ, defined as the ratio between the length of all cracks in one tube and the tube height), CFE and SEA had a decreasing trend, while length ratio had little effect on initial peak load.

Fracture energy and mechanical characteristics of self-compacting concretes including waste bladder tyre

Management of solid wastes is one of the most important environmental problems in the world. Waste tyres are also one of these solid wastes. The growing number of waste tyres that are stocked every year brings problems in respect of human health, environmental pollution, and also causes esthetical problems. The main purpose of this study is to investigate the effect of waste tyre addition on self-compacting concretes’ mechanical characteristics and fracture properties under bending. In this study, waste bladder tyres (RA) mechanically cut in 25, 50 and 75mm lengths were used by volumetric replacement of coarse aggregates in self-compacting concretes (SCC). Unit weight, flow, J-ring, column segregation, water absorption, 28days of compressive strength, ultrasound pulse velocity and fracture energy tests were applied on concretes obtained by replacement of coarse aggregates in 5%, 10% and 15% ratios by volume. Also, Scanning Electronic Microscope (SEM) and Energy Distribution Spectroscopy (EDS) analyses of the samples were examined. In the study, it was determined that RA replacement decreases unit weight of fresh concrete; when RA length ratio increases, it becomes difficult for the concrete to pass through reinforcement openings; in hardened concrete samples dry unit weight decreases; 10% fibre addition increases compressive strength values; after the ultrasonic pulse velocity measurement, the concretes are included in “good” quality concrete classifications. As a conclusion, it was determined that 25mm long 10% rubber aggregate replacement to self-compacting concretes can give optimum results.

Coherence property of mid-infrared supercontinuum generation in tapered chalcogenide fibers with different structures

We have numerically investigated the coherence property of mid-infrared supercontinuum generation in tapered step-index chalcogenide fibers with different structures. The pump source is a 4 μm laser with pulse width of 500 fs and peak power of 1 kW. The length ratio is the ratio of transition region length near the laser input to the other transition region length near the output. We calculate the bandwidth and the spectrally averaged coherence of the supercontinuum spectra generated in fibers with different length ratios under the same pumping condition. Numerical results show that as the length ratio increases, the bandwidth decreases from 4.84 μm to 4.11 μm while the spectrally averaged coherence increases from 0.53 to 0.9 and then jitters near the maximum. The length ratio within 1–1.5 is preferable to keep a balance between bandwidth and coherence.

Computerized Adaptive Testing: The Capitalization on Chance Problem

This paper describes several simulation studies that examine the effects of capitalization on chance in the selection of items and the ability estimation in CAT, employing the 3-parameter logistic model. In order to generate different estimation errors for the item parameters, the calibration sample size was manipulated (N = 500, 1000 and 2000 subjects) as was the ratio of item bank size to test length (banks of 197 and 788 items, test lengths of 20 and 40 items), both in a CAT and in a random test. Results show that capitalization on chance is particularly serious in CAT, as revealed by the large positive bias found in the small sample calibration conditions. For broad ranges of theta, the overestimation of the precision (asymptotic Se) reaches levels of 40%, something that does not occur with the RMSE (theta). The problem is greater as the item bank size to test length ratio increases. Potential solutions were tested in a second study, where two exposure control methods were incorporated into the item selection algorithm. Some alternative solutions are discussed.

Characteristics of thickness distribution of tailor-welded tube hydroforming

Both experimental and mechanical analyses were carried out to investigate the characteristics of thickness distribution for tailor-welded tube (TWT) hydroforming with dissimilar thickness. Then, the effects of weld-seam position and thickness difference were also revealed. A multiple-diameter tube was formed to reveal the characteristics and the regularity of thickness distribution during TWT hydroforming. It is indicated that there are obvious fluctuations in thickness distribution though the TWTs have the same expansion ratio. The thinning ratio of thinner tube is bigger than that of thicker tube especially in the zone closed to the weld-seam. The difference in thinning ratio between two tube segments can reach 9%. Consequently, sudden and large fluctuation of thickness appears in the zone nearby the weld-seam. The difference in thinning ratio between thinner and thicker tubes enlarges as the thickness difference increases, but improves as length ratio increases. Different strain states are the main reason to induce nonuniform thickness distribution. The difference in thickness is the main reason to induce different strain states on thinner and thicker tubes.