Fineness Ratio Research Articles

Effect of sand granulometry on the egg hatchling success of the sea turtle Caretta caretta

The environmental characteristics of nesting sites of sea turtles may directly interfere with the egg hatchling success. The objective of the present study was to evaluate the factors that affect the success of hatchling in the nests of the loggerhead sea turtle (Caretta caretta). Data from 37 nests of C. caretta from the coast of Mata de São João, Bahia, northeastern Brazil, were obtained from TAMAR, Sauípe station. Samples of sand were collected in each nest to determine the granulometry. A significant negative relationship was found between the stillborn rate and the fine sand ratio (r2 = 0.119; p = 0.036), indicating that a larger fraction of fine sand had a positive effect on nest hatchling success. The egg laying date also had a significant influence on the rate of stillbirths (r2 = 0.163; p = 0.013), with a trend towards a higher stillbirth rate, the later the laying date of the eggs. There is indication that the transfer of eggs to sites with more favorable characteristics may be considered as a potential alternative to increase the hatchling success rate of C. caretta eggs.

Preparation and microstructure of fly ash geopolymer paste backfill material

As a new paste backfill material, geopolymer cemented coal gangue-fly ash backfill is prepared from fly ash geopolymer and spontaneous combustion gangue and can be beneficial to the cleaner production of coal mines and coal-fired power plants. A new mixing technique, in which a small amount of fly ash was mixed with cement, slag and water and allowed to react for a period of time before an aggregate and residual fly ash were added, was proposed. The influences of the solid mass concentration, the fine gangue ratio and the fly ash content on the workability and strength of the paste backfill material were analyzed, and ratio optimization was carried out using the response surface method, multi-objective multi-verse optimization and the desirability function approach. The results show that the optimal mixture is obtained when the mass concentration is 79.65%, the fine gangue rate is 57.19%, and the fly ash content is 15.67% of the total mass. The new mixing technique makes the fly ash more active to stimulate the early formation of calcium silicate gel and calcium silicate hydrate gel that improve the aggregate formation strength. In the later stage, amorphous hydrated calcium aluminate gel-coated ettringite and calcium carbonate formed a flocculation structure between the fly ash particles that gradually formed a condensation-crystallization structure. The research results can make extensive use of fly ash and gangue to promote cleaner production.

Experimental investigation of microstructural changes in soils eroded by suffusion using X-ray tomography

Internal erosion is a complex phenomenon which represents one of the main risks to the safety of earthen hydraulic structures such as embankment dams, dikes or levees. Its occurrence may cause instability and failure of these structures with consequences that can be dramatic. The specific mode of erosion by suffusion is the one characterized by seepage flow-induced erosion, and the subsequent migration of the finest soil particles through the surrounding soil matrix mostly constituted of large grains. Such a phenomenon can lead to a modification of the initial microstructure and, hence, to a change in the physical, hydraulic and mechanical properties of the soil. A direct comparison of the mechanical behaviour of soil before and after erosion is often used to investigate the impact of internal erosion on soil strength (shear strength at peak and critical state) using triaxial tests. However, the obtained results are somehow contradictory, as for instance in Chang’s study (Chang and Zhang in Geotech Test J 34(6):579–589, 2011), where it is concluded that the drained strength of eroded soil decreases compared to non-eroded soil, while both Xiao and Shwiyhat (Geotech Test J 35(6):890–900, 2012) and Ke and Takahashi (Geotech Test J 37(2):347–364, 2014) have come to the opposite conclusion. A plausible explanation of these contradictions might be attributed to the rather heterogeneous nature of the suffusion process and to the way the coarse and fine grains are rearranged afterwards leading to a heterogeneous soil structure, a point that, for now, is not taken into account, nor even mentioned, in the existing analyses. In the present study, X-ray computed tomography (X-ray CT) is used to follow the microstructure evolution of a granular soil during a suffusion test, and, therefore, to capture the induced microstructural changes. The images obtained from X-ray CT reveal indeed that fine particles erosion is obviously not homogeneous, highlighting the existence of preferential flow paths that lead to a heterogeneous sample in terms of fine particles, void ratio and inter-granular void ratio distribution.

Rayleigh-Ritz method-based analysis of dry coupled horizontal-torsional-warping vibration of rectelliptic open-section containership bare-hulls

The coupled horizontal-torsional-warping vibration of a thin-walled open-section 7800 TEU container ship bare-hull, modelled as a non-uniform girder, is analysed by the efficient energy-based Rayleigh-Ritz method, in order to generate the dry asymmetric vibration frequencies. Since the centre of gravity is within the hull and the shear centre is below the keel, the horizontal and torsional modes of vibration are highly coupled. An open section is also prone to warping. In a novel attempt, the bare-hull geometry is generated mathematically, using section-wise closed-form semi super-ellipses (Lame’s curves). The main dimensions, weight distributions, and fineness ratios are preserved, and closed-form expressions of sectional properties become available in the process. The hull has arbitrarily (non-mathematically) varying mass, bending stiffness, warping stiffness, and shear stiffness distributions along the length. The non-uniform beam modeshape in horizontal/torsional vibration is assumed to be a weighted sum of the uniform beam horizontal/torsional modeshapes. Several benchmark cases of simpler geometry have been analysed first, for both torsion-warping vibration, and coupled horizontal-torsional-warping vibration. Pontoon approximation of the containership has been analysed and validated. Subsequently, the coupled dry vibration frequencies are obtained for the open deck non-uniform girder, and compared with published results.

Improvement of semi-resolved CFD-DEM model for seepage-induced fine-particle migration: Eliminate limitation on mesh refinement

The semi-resolved CFD-DEM model, proposed in our previous paper (Cheng et al., 2018) for the modelling of seepage-induced fine-particle migration through coarse skeleton in gap-graded soils, is improved through using Gaussian-based weighting function for fine particle-fluid coupling based on locally averaging theory. By doing so, it eliminates the limitation on fine particle-fluid mesh size ratio and thereby facilitates capturing detailed flow pattern through the coarse skeleton by refining fluid meshes. The improved semi-resolved CFD-DEM model is validated by Particle Image Velocimetry results of velocity field of fine glass beads migration through a simple coarse skeleton.

Control of Aerodynamic Drag and Heating of Nose Cones Through Taper Spikes

The present work numerically and experimentally investigates Mach 5.8 flow past passively modified nose cone configurations such as taper/stepped taper spiked, spherically blunted, and parabolic nose cones at a fineness ratio of 3.6 and zero angle of attack in order to determine the best passively modified geometry that provides the control of both the aerodynamic drag coefficient and surface heat flux. The velocity vectors show the flow directions/recirculation zones and so on at the root of the taper as well as stepped taper spikes, whereas the Mach number contours show the features of shock in front of the taper/stepped taper spikes as well as the nose tip of the taper/stepped taper spiked blunted and parabolic nose cones. The present study reveals that the “stepped taper spiked parabolic nose cone” configuration provides lowest aerodynamic drag coefficient and surface heat flux as compared with all the other nose cone configurations investigated. The modifications in the flow/shock features such as the conversion of strong curved shock into weaker oblique shock waves, flow deceleration, and so on, at the root of the spike due to backward-facing steps in “stepped taper spiked parabolic nose cone” may be the reason for achieving lower aerodynamic drag/heating.

Use of roller compaction and fines recycling process in the preparation of erlotinib hydrochloride tablets

This study focuses on improving the manufacturing process for a generic immediate-release tablet containing erlotinib hydrochloride by adding a fines recycling process during roller compaction. Due to the large fraction of small-sized API particles, the starting powder mixture was inconsistently fed into the roller compactor. Consequently, poorly flowing granules with a high ratio of fines were produced. A fines recycling step was, therefore, added to the existing roller compaction process to minimize the risks caused by the poor granule flow. A laboratory scale roller compactor and a tablet simulator were used to prepare granules at various process conditions. The effect of dry granulation parameters on size distribution, API distribution, powder flow, compaction properties, and dissolution profile was evaluated. The granule batch after fines recycling had markedly improved size distribution and flowability while maintaining acceptable tablet tensile strength and rapid dissolution profile. The application of the fines recycling process at commercial scale resulted in reliable dissolution performance and batch-to-batch consistency, which were further confirmed by bioequivalence to the reference product. Understanding how granule properties are impacted by the fines recycling process may enable fine-tuning of the dry granulation process for optimal product quality.

The Dosage of Superplasticizer in Cemented Coal Waste Backfill Material Based on Response Surface Methodology

Cemented coal waste backfill material (CCWBM) is developed for backfilling the goaf in coal mines. As fresh CCWBM slurry is generally transported into underground openings through a pipeline, the fluidity of fresh slurry becomes one of the most important properties. Adding superplasticizer is considered to improve the flow performance of the slurry without alerting the mechanical performance of filling body. The dosage of superplasticizer (SP) is related to filling cost, thus response surface methodology (RSM) is adopted to study the influence of material composition on SP when target slump is 250 mm. The effects of fly ash content, fine gangue ratio, and mass concentration on SP are analyzed using the software of Design-Expert and central composite design (CCD), and models are established for SP. Results show that the SP model coincides greatly with the test results and can be applied to analyze and predict SP in CCWBM. Mass concentration, fly ash content, and fine gangue ratio influence SP from high to low. The interaction of fine gangue ratio and mass concentration between SP is the most significant. The fact that the improved aggregate space model can be applied to analyze the fluidity of CCWBM is proved too. The research results provide guidance for the design and preparation of CCWBM with favourable performance and low cost in practical production.

The Mystery behind the Fine Structure Constant Contracted Radius Ratio Divided by the Mass Ratio? A Possible Atomist Interpretation

This paper examines various alternatives for what the fine structure constant might represent. In particular, we look at an alternative where the fine structure constant represents the radius ratio divided by the mass ratio of the electron, versus the proton as newly suggested by Koshy [1], but derived and interpreted here based on Haug atomism (see [2]). This ratio is remarkably close to the fine structure constant, and it is a dimensionless number. We also examine alternatives including the proton mass divided by the Higgs mass, which appears to be another possible candidate for what the fine structure constant might represent.

Coronary artery calcium and the competing long-term risk of cardiovascular vs. cancer mortality: the CAC Consortium.

Coronary artery calcium (CAC) is the strongest predictor of cardiovascular disease (CVD), yet is also associated with chronic non-CVD such as cancer. We performed this analysis in order to describe the association of CAC with CVD vs. cancer mortality. The CAC Consortium is comprised of 66636 scans performed in asymptomatic patients without known CVD. The mean age was 54 ± 11 years and 67% of participants were men. Cause of death was ascertained from death certificates. The association of CAC with cause-specific mortality was calculated using Fine and Gray sub-distribution hazard ratio (SHR) models, which account for competing causes of death. There were 3158 deaths over a median 12 ± 4 years follow-up (37% cancer and 32% CVD). Cancer was the leading cause of death when CAC = 0 (50%) with CVD overtaking cancer when baseline CAC >300. Compared to participants with CAC = 0, the SHR for CVD mortality was 1.44 [95% confidence interval (CI) 1.14-1.81], 2.26 (95% CI 1.76-2.90), and 3.68 (95% CI 2.90-4.67) for patients with CAC 1-99, 100-299, and ≥300, and the SHR for cancer was 1.04 (95% CI 0.88-1.23), 1.19 (95% CI 0.98-1.46), and 1.30 (95% CI 1.07-1.58). Cancer was the leading cause of death for patients with baseline CAC = 0, whereas CVD overtook cancer above a threshold of CAC >300. These results argue for a focused approach for patients at the extremes of CAC scoring while suggesting that combined CVD and cancer primary prevention strategies for patients with intermediate CAC scores may significantly decrease mortality from the two leading causes of death.

Modelling a spade rudder as a hollow two-way tapered Kirchhoff’s plate : free dry and wet vibration study with numerical verification

A semi-analytical approach to free dry and wet vibration of a trapezoidal, 2-way tapered, pivoted hollow spade rudder is presented. The rudder is modeled as a hollow Kirchhoff’s plate, with a NACA0018 profile chord section. The rudder pivot is modeled as a combination of a translational spring and a rotational spring. The span-wise and chord-wise non-uniform beam vibration is first analyzed by the Rayleigh-Ritz method, to establish the non-uniform beam modeshapes, which act as admissible functions to the Galerkin’s method for plate vibration. Eigenvalue analysis generates the plate natural frequencies and the plate modeshapes. Alternately, uniform beam modeshapes themselves are used as admissible functions into the Galerkin’s method. Frequencies are analyzed for various pivot positions, taper ratios, and NACA sections. For the wet vibration, constant strength source distribution technique is used to generate the added mass of a 2D aerofoil. Also, 3D panel method is used to generate the modal added masses, and hence the wet natural frequencies. The added mass coefficient is generated for various aerofoil fineness ratios, pivot fixities, taper ratios, aspect ratios.

A dual-mode variable optical power splitter using a Digital Spatial Light Modulator and a variable focus lens

This paper describes the design of a variable optical power splitter which splits input optical signal power into variable ratios between two output ports. The proposed design is a hybrid scheme which uses a conventional Digital Spatial Light Modulator (DSLM) and a tunable focus Electrically Tunable Lens (ETL). The proposed splitter has an inherent dual-mode of operation and is capable of operating in a DSLM-only, ETL-only or a hybrid DSLM/ETL mode depending on the desired accuracy of the power split ratio. We show that the improved power splitter design can potentially offer a fine split ratio control through additional ETL focal length control. Moreover, it eliminates the need of ascertaining an exact random image pattern through hit-and-trial for an exact split ratio in a DSLM-only splitter mode. The DSLM is used to obtain the closest value to the desired split ratio using a fixed circular pattern with a variable radius while the ETL is tuned for further fine-tuning the split ratio in order to get closer to the required value. We also show that a dual-mode control delivers multiple possible solutions for any desired split ratio. Experimental results validate the working of the proposed splitter design.

Investigation of properties and performances of Polyvinyl Alcohol (PVA) fiber-reinforced rubber concrete

In this study, the Polyvinyl Alcohol (PVA) fiber was introduced to improve the performance of the rubberized concrete. This study experimentally investigated the mechanical performance and durability of Polyvinyl Alcohol (PVA) fiber-reinforced rubber concrete. The waste rubber particles (mesh size #10–#30) were selected to partially replace fine aggregates in the plain concrete. In addition, the rubber particles were pre-treated with an alkali solution to enhance the interface bond with cement paste. The fiber-reinforced rubber concrete samples were prepared with different fine aggregate replacement ratios based on the volume of fine aggregate (15%, 20%, and 25%) and a selected fiber content (0.5% based on the total volume of the mixture). For those samples, the mechanical properties, including compressive strength, flexural behavior, and fracture energy were evaluated to compare with control samples. The results showed that fiber-reinforced samples can largely improve the post-cracking extension and fracture energy. The results of electrical resistivity test indicated the reduced permeability in the fiber-reinforced rubber concrete. The durability performance including Alkali-Silica reaction (ASR) expansion, drying shrinkage and freeze-thaw resistance were also investigated and compared with the control samples. All the durability performances were enhanced through rubber stress release and fiber crack bridging. Therefore, the PVA-fiber reinforced rubber concrete can improve durability and ductility of cementitious materials for structure construction and also can facilitate the recycling of waste rubber into cementitious materials.

Differences in the uptake and bioconcentration of dichlorodiphenyltrichloroethane by eight vegetable cultivars and their health risk assessments

Dichlorodiphenyltrichloroethane (DDT) is not easily degraded in soils, which will pose a threat to human health. We investigated the differences of eight vegetables' capacity to take up DDT, removing DDT from soil, and tolerating DDT (monitoring the responses of growth, root morphology and photosynthesis of vegetables to DDT). These vegetables included Chinese mustard (two genotypes, B.jf and B,jm), napa cabbage (two genotypes, B.coz and B.coc) and Bok choy (four genotypes, B.cz, B.cq, B.cs and B.chg). The results demonstrated that 5 mg kg−1 DDT did not display significant effects on the growth of most vegetables in this study. As compared to the control, 5 mg kg−1 DDT significantly increased the shoot and root biomass, the fine root numbers, and the fine root ratio for the genotype of B.chg. However, 5 mg kg−1 DDT exposure showed a negative effect on the shoot growth of two genotypes of napa cabbage. In general, 5 mg kg−1 DDT did not significantly affect the photosynthesis and root morphology of most vegetables in this study. Consuming these vegetables had a low non-cancer health risk, but showed a high cancer health risk. In addition, among the eight vegetables, B.chg accumulated less DDT in the edible parts and had low values of HRnon-cancer and HRcancer for consuming these vegetables containing DDT. Planting these vegetables might promote the degradation of DDT reducing its residual amount in soil.

Thermally Assisted Electrohydrodynamic Jet High‐Resolution Printing of High‐Molecular Weight Biopolymer 3D Structures

AbstractHigh‐molecular biodegradable and bioresorbable polymers are widely used in tissue engineering applications. In this work, a high‐resolution 3D printing technique, thermally assisted electrohydrodynamic jet (TAEJ) printing, is developed for patterning high‐molecular weight biopolymer 3D structures. Boiling point graded polyvinylpyrrolidone (PVP) and PVP/polycaprolactone biopolymer inks are prepared. The resultant effects of electrohydrodynamic force and thermal field are applied on these polymer ink, to form a stable and controllable sub‐micrometer scale jet at the needle tip. Fine jet 2D period patterns and 3D high aspect ratio structures of the biopolymer inks are directly printed using fine jet at a typical feature size of sub‐micrometer. Furthermore, TAEJ printing of 3D heterogeneous high‐molecular weight biopolymer scaffold is demonstrated. Cell culture shows high biocompatibility and cartilage regeneration in vitro, which provides a great potential for tissue engineering applications.

Study of some physical wool characterization in Arabi ewes in Erbil Governorate

This study was carried out at Private flock in Murtkah District - Erbil Governorate. Samples of wool were taken from mid-side of 72 Arabi ewes during May, 2017. to study the effect of ewes age and the sex of the lambs on the physical wool characteristics The overall means of raw fleece weight, clean fleece, fiber diameter, crimps, staple length and fiber length were 1653.75 g, 79.06%, 28.24 micron, 1.33 cm, 9.36 cm and 16.03 cm respectively. The percentages of the fibers of each of Fine, Coarse and Kemp were 52.42, 38.89 and 8.68% respectively. and S/P ratio 1.27. Age of ewe effects appeared to be significant on raw fleece weight and coarse fiber (p ≤ 0.05), also on fine fiber and (S/P) ratio (p ≤ 0.01) only, while the effects of sex of lamb were non-significant on all physical wool properties except the percentage of kemp fiber (p ≤ 0.05). Although the maximum R-square increased very little gradually in the equation to predict fleece weight depending on body weight and dimensions, the simplest equation includes body weight could be considered the most significant (P<0.01) and more reliable than others to predict fleece weight (The equation is: fleece weight = 353.41 + 31.84 (body weight). The multiple regression equations were calculated to predict clean wool percentage, staple length, fiber length, crimps, fine fiber percentage, coarse fiber percentage, and S/P ratio from fleece weight, body weight and dimensions and the maximum R-square for all characteristics were very small. Fiber diameter could be predicted using the formula of multiple regression includes body weight and length and chest depth according to the maximum R-square (P<0.01). While Kemp fiber percentage could be predicted using the formula includes body weight, fleece weight and Shoulder height. Only the simple regression equation of Fleece weight on body weight was significant (P<0.01) with R-square (0.19). The correlation coefficient was done among all studied characteristics and ranged between -0.69 (p<0.01) (between fine fiber and coarse fibers) and 0.94 (p<0.01) (between fine fiber and S/P ratio). It was concluded that wool properties of Arabi sheep were not at standard level especially in both fine and Kemp properties and need to be improved

Pretreatment of natural perlite powder by further milling to use as a supplementary cementitious material

Replacing a portion of ordinary Portland cement (OPC) with natural pozzolans may be an effective solution to reduce the carbon footprint of the concrete industry and construction costs, and to improve concrete durability in general terms. However, some natural pozzolans, such as perlite, need to be pretreated to be reactive enough and satisfy the minimum standard qualifications of the concrete industry. This research investigated the effectiveness of milling of natural perlite as an alternative to calcination, which is the more common reactivation method. For this purpose, the effects of replacing OPC with natural perlite powder (NPP) were studied at three different levels of fineness and replacement ratios. A variety of tests for the mechanical and transport properties of the concrete were carried out, including a compressive strength test, a surface electrical resistivity test, a water penetration test, a rapid chloride permeability test, and a rapid chloride migration test. These tests conducted on 14 different types of concrete mixtures with various ratios of water-to-cementitious materials (W/Cm), cement content, and replacement ratios. The results demonstrated that increasing the fineness of natural perlite could be an effective method to reactivate NPP, leading to almost the same compressive strength while improving the transport properties significantly.

Influence of Replacement Rate of Fine Aggregate by Blast Furnace Slag Sand on Fresh Properties of Mortar

For enlarging and promoting usage of blast furnace slag sand and improving construction performance of concrete with it, the behavior of the mortar under both static and dynamic, using vibrator, conditions were confirmed from the viewpoint of plastic viscosity, filling property and bleeding rate. As the results, within the scope of this experiment, by investigating the mixing ratio at which the plastic viscosity changes from the vibration plasticity viscosity obtained by the feather penetration type viscosity measurement test, it was considered that the appropriate fine aggregate mixing ratio can be estimated. Furthermore, the pore water pressure was measured for a sample in which the mixing ratio of the fine aggregate was changed, and the possibility of evaluating the fresh properties from the tendency of disappearance of pore water pressure after stopping the vibration was indicated.

Effect of fineness and replacement ratio of ground fly ash on properties of blended cement mortar

This study presents an experimental investigation on the effect of ground fly ash fineness and replacement ratio on properties of blended cement mortar. Class F fly ash was ground into three different fineness values of 4610 cm2/g, 5690 cm2/g, and 6300 cm2/g with ball grinding machine and used as a replacement ratios of 0%, 10%, 15%, and 20% by weight of cement to produce the blended cement mortars. Compressive strength test, water absorption, mercury intrusion porosimetry (MIP) test, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis were performed. Test results show that the use of fly ash resulted in significant improvement in compressive strength and substantial decrease in water absorption and capillary pores for blended cement mortars compared to OPC mortar. The mortars with fineness value of 5690 cm2/g and FA replacement ratio of 20% has the highest compressive strength and lowest water absorption and smallest porosity. The XRD analysis showed that Ca(OH)2 is one of the hydration products during the hydration reaction. When fly ashes were incorporated into the blended cement mortars, the intensity peaks of Ca(OH)2 in the XRD patterns decreased. The increasing replacement ratio of fly ash decreased Ca(OH)2. Based on the results, both the fly ash fineness and the fly ash replacement ratio have a significant influence on the properties of blended cement mortar.

Effect of fineness ratios of 0.75–2.0 on aerodynamic drag of freestream-aligned circular cylinders measured using a magnetic suspension and balance system

The drag coefficients of freestream-aligned circular cylinders of fineness ratios of 0.75–2.0 were investigated with a magnetic suspension and balance system (MSBS). The objective was to find the critical geometry, that is, the fineness ratio at which the drag coefficient becomes the local maximum within this ratio range. The experiments were conducted using the 1-m MSBS at the low turbulence wind tunnel at the Institute of Fluid Science, Tohoku University. The drag and base pressure coefficients of various cylinders were measured. The freestream velocity was varied to produce flows with Reynolds numbers ranging from $$0.6\times 10^5$$ to $$1.0\times 10^5$$ . The drag coefficient monotonically decreases as the fineness ratio increases and no critical geometry or local maximum of the drag coefficient is found in the range we investigated. The base pressure coefficient decreases as the fineness ratio increases. The temporal fluctuations of the base pressure of the models with fineness ratios of 0.75, 1.0, and 1.2 are approximately twice as large as that of the model with a ratio of 2.0. The relationship between the fineness ratio and the drag coefficient is similar to that between the fineness ratio and the base pressure coefficient, similar to the findings of previous studies of two-dimensional bodies.