Straight Portion Research Articles

Influence of particle shape on pebble transport in a mixed sand and gravel beach during low energy conditions: Implications for nourishment projects

Beach nourishments using coarse-gravel sediments are becoming a frequent practice to buffer coastal erosion, but usually little attention is spent on fill material characteristics. A better understanding of the influence of sediment characteristics on transport is crucial to establish the best compatibility of fill material with native beach sediments. Pebble transport is here investigated by means of the RFID tracing technique. The main purpose of the experiment was to verify whether the prevalent shapes populating the beach (disks and spheres) show a different transport under low energy conditions. Tracers were injected in a small and straight portion of a mixed sand and gravel beach, deploying couples of marked particles of the same size (one sphere and one disk-shaped pebble on the main geomorphic elements of the beach face), in order to avoid size influence on transport. Tracer recovery was undertaken 6 and 24 h after the injection and wave characteristics were measured during the whole experiment duration by means of a S4 directional wave gauge. After 6 h the marked pebbles underwent significant displacement with a prevalent longshore component, which became evident after 24 h. The swash zone proved to be the most dynamic area of the beach. Spheres covered longer distances and resulted more dynamic than disks, thanks to their capability to roll-over in the swash zone. Lately, many experiments have been carried out with marked pebbles, but this is the first time that an experiment is conceived to prove how shape influences pebble transport. Disks are more subject to burial and due to their higher dynamicity spheres are preferred to disks for nourishment fill material. A fill material comprised of spheres is regularly responding to hydrodynamic forces and can positively speed up the beach recovery after storms especially in highly dynamic systems like pocket beaches, typically subjected to beach rotation processes. The results show an implication for coastal managers having to choose fill sources for replenishments.

When integration sparsification fails: Banded Galerkin discretizations for Hermite functions, rational Chebyshev functions and sinh-mapped Fourier functions on an infinite domain, and Chebyshev methods for solutions with C[formula omitted] endpoint singularities

Chebyshev polynomial spectral methods are very accurate, but are plagued by the cost and ill-conditioning of dense discretization matrices. Modified schemes, collectively known as “integration sparsification”, have mollified these problems by discretizing the highest derivative as a diagonal matrix. Here, we examine five case studies where the highest derivative diagonalization fails. Nevertheless, we show that Galerkin discretizations do yield banded matrices that retain most of the advantages of “integration sparsification”. Symbolic computer algebra greatly extends the reach of spectral methods. When spectral methods are implemented using exact rational arithmetic, as is possible for small truncation N in Maple, Mathematica and their ilk, roundoff error is irrelevant, and sparsification failure is not worrisome. When the discretization contains a parameter L, symbolic algebra spectral methods return, as answer to an eigenproblem, not discrete numbers but rather a plane algebraic curve defined as the zero set of a bivariate polynomial P(λ,L); the optimal approximations to the eigenvalues λj are in the middle of the straight portions of the zero contours of P(λ;L) where the isolines are parallel to the L axis.

Freeze-casting porous chitosan ureteral stents for improved drainage

As a new strategy for improved urinary drainage, in parallel to the potential for additional functions such as drug release and self-removal, highly porous chitosan stents are manufactured by radial, bi-directional freeze-casting. Inserting the porous stent in to a silicone tube to emulate its placement in the ureter shows that it is shape conforming and remains safely positioned in place, also during flow tests, including those performed in a peristaltic pump. Cyclic compression tests on fully-hydrated porous stents reveal high stent resilience and close to full elastic recovery upon unloading. The drainage performance of the chitosan stent is evaluated, using effective viscosity in addition to volumetric flow and flux; the porous stent’s performance is compared to that of the straight portion of a commercial 8 Fr double-J stent which possesses, in its otherwise solid tube wall, regularly spaced holes along its length. Both the porous and the 8 Fr stent show higher effective viscosities, when tested in the silicone tube. The performance of the porous stent improves considerably more (47.5%) than that of the 8 Fr stent (30.6%) upon removal from the tube, illustrating the effectiveness of the radially aligned porosity for drainage. We conclude that the newly-developed porous chitosan ureteral stent merits further in vitro and in vivo assessment of its promise as an alternative and complement to currently available medical devices. Statement of SignificanceNo papers, to date, report on porous ureteral stents, which we propose as a new strategy for improved urinary drainage. The highly porous chitosan stents of our study are manufactured by radial, bi-directional freeze casting. Cyclic compression tests on fully-hydrated porous stents revealed high stent resilience and close to full recovery upon unloading. The drainage performance of the chitosan is evaluated, using effective viscosity in addition to volumetric flow and flux, and compared to that of the straight portion of a commercial 8 Fr double-J stent. The performance of the porous stent improves considerably more (47.5%) than that of the 8 Fr stent (30.6%) upon removal from the tube, illustrating the effectiveness of the radially aligned porosity for drainage. While further studies are required to explore other potential benefits of the porous stent design such as antimicrobial behavior, drug release, and biodegradability, we conclude that the newly-developed porous chitosan ureteral stent has considerable potential as a medical device.

Performance of a buried pipeline along the dip of a slope experiencing accidental sliding

Contrary to highways, major pipelines often have to be installed crossing hills or mountain ridges, following the dip of the slope. Slope movements that may be triggered by an earthquake, heavy rainfall, an excavation at its toe, or long-term creep, constitute major hazards that must be considered in design. This paper studies numerically the interaction of a steel pipeline with a rotational slide originating at the crest of a slope and evolving in the direction of the pipeline axis. Different pipeline-slide mechanisms are examined: a reference slide taking place in a rather shallow slope in which the sliding surface crosses the pipe over its straight portion, a deeper scenario where the toe of the slide interacts with the bottom elbow element of the pipeline, and two much steeper scenarios. A two-step finite-element methodology is developed and validated against several published experiments. The analysis simulates realistically the soil sliding process and all possible modes of pipeline failure. The pipeline performance is discussed for a range of internal pressure scenarios: from empty to full operating at maximum allowable pressure (pmax). It is found that the relative position of the slip-line to the pipeline axis (at their intersection) determines the amount of bending induced in the pipeline and eventually the vulnerability of the installation. For empty pipes the prevailing failure mode is inward buckling, whereas pressurised pipelines rupture at larger displacements due to excessive accumulation of tensile strains. When the slip-line of the sliding mass crosses the toe of the slope, excessive bending is experienced at the lower bend of the installation, which is translated into a compressive force, invariably speeding up pipeline failure. Here the failure mode is always buckling: inward for non-pressurised pipes and outward for non-zero internal pressures.

A splice site variant in INPP5E causes diffuse cystic renal dysplasia and hepatic fibrosis in dogs.

Ciliopathies presenting as inherited hepatorenal fibrocystic disorders are rare in humans and in dogs. We describe here a novel lethal ciliopathy in Norwich Terrier puppies that was diagnosed at necropsy and characterized as diffuse cystic renal disease and hepatic fibrosis. The histopathological findings were typical for cystic renal dysplasia in which the cysts were located in the straight portion of the proximal tubule, and thin descending and ascending limbs of Henle’s loop. The pedigree of the affected puppies was suggestive of an autosomal recessive inheritance and therefore, whole exome sequencing and homozygosity mapping were used for identification of the causative variant. The analyses revealed a case-specific homozygous splice donor site variant in a cilia related gene, INPP5E: c.1572+5G>A. Association of the variant with the defect was validated in a large cohort of Norwich Terriers with 3 cases and 480 controls, the carrier frequency being 6%. We observed that the identified variant introduces a novel splice site in INPP5E causing a frameshift and formation of a premature stop codon. In conclusion, our results suggest that the INPP5E: c.1572+5G>A variant is causal for the ciliopathy in Norwich Terriers. Therefore, genetic testing can be carried out in the future for the eradication of the disease from the breed.

English

National Highways of Bangladesh, where majority of fatal accident takes place, are considered as the accident-prone location. Statistics revealed that despite some major initiatives undertaken to improve road safety, death rate at National Highways of Bangladesh is quite high compared to other developed as well as developing nations. To understand the relationship between injury severity and accident factors, investigation concentrate on different influential factors are responsible for injury severity. Micro Computer Accident Analysis Packages (MAAP5), data of Bangladesh Police from 2004-2015, is used in this investigation to identify the probability of fatal and grievous injury. Preliminary analysis revealed that almost 80% accident recorded as fatal accident and majority of the accidents occurred in fair-weather condition, at straight portion of the road, in non-rush hour and in broad daylight. Conversely, three level of injury severity (dependent variables) was considered in the econometric analysis namely, fatal, grievous and simple injury. Ordered Probit Model examined the dependent variables based on several explanatory variables such as time factors, road geometry, environmental conditions, vehicle categories, driver attitudes, passenger and pedestrian behavior. Considering different level of independent variables, it is found that under the heading of collision type, hit Pedestrian is the statistically significant variable that creates severe injury. Considering vehicle characteristics, non-motorized vehicle, bus and motorcycle was found to be the most vulnerable group of road users in Bangladesh and the probability of fatal injury is much higher for vehicle with multiple defects. This investigation also pointed on some remedial measures that will help the decision maker to set up long as well as short term strategies. For instance, installation of physical barrier at the accident-prone location will minimize the pedestrian fatalities and isolation of non-motorized vehicle and motorcyclist from main carriageway, which would dramatically reduce injury severity on highways. Finally, this investigation also provides some specific guideline for future steps on injury severity analysis in Highways of Bangladesh. Key words: National Highway, Fatal Accident, Ordered Probit Model, Variables

Identifying the dominant physical processes for mixing in full-scale raceway tanks

Abstract Open racetrack flumes represent the most common reactor for algae cultivation in the biodiesel industry, however, despite numerous experimental and numerical studies into reactor modifications, conditions remain suboptimal for algal growth. In response, a full-scale racetrack flume was constructed at the Ecohydraulics and Ecomorphodynamics Laboratory at the University of Illinois. Experiments on the racetrack flume were conducted for various depth and velocity conditions, using acoustic doppler velocimetry and surface particle velocimetry to characterize mean and turbulent velocity statistics, and dissolved oxygen measurements to investigate the effect of turbulent structures on gas transfer at the water-air interface. Longitudinal bed modifications were introduced to induce secondary flows in the straight portions of the flume. Semicircular and triangular bars of two different sizes were tested in an effort to increase the transfer velocity at the free surface. A range of flow structures were observed including secondary currents of Prandtl's first and second kinds, vortex shedding off of bend vanes, and periodic oscillations in surface lateral currents. Findings indicate that bend dynamics introduce the strongest and most resilient flow structures, and any attempt to induce vertical mixing or accelerate transfer velocities at the free surface will need to utilize or overwhelm these existing structures.

Mechanical splicing of superelastic Cu–Al–Mn alloy bars with headed ends

This paper examines the feasibility of mechanical splicing using a steel coupler to connect headed ends of superelastic Cu–Al–Mn alloy (Camalloy) bars and steel reinforcing bars to be used in concrete structures. Although threading of Camalloy is as easy as that of steel, mechanical splicing using threaded ends requires machining of Camalloy bars into dog-bone shape to avoid brittle fracture at the threaded ends. The machining process requires significant time and cost and wastes substantial amount of the material. This paper attempts to resolve this issue by applying mechanical splicing using steel couplers to connect headed ends of Camalloy and steel reinforcing bars. To study its feasibility, we prepare 3 specimens wherein both ends of each Camalloy bar (13 mm diameter and 300 mm length) are connected to steel reinforcing bars. The specimens are tested under monotonic, single-cycle, and full-cycle tension loading conditions. From these tests, we observed (1) excellent superelasticity with recoverable strain of around 6% and (2) large ductility with fracture strain of over 19%. It should be emphasized here that, in all the specimens, ductile fracture occurred at the locations apart from the headed ends. This is in sharp contrast with brittle fracture of headed superelastic Ni–Ti SMA bars, most of which took place around the headed ends. From the results of the microstructural analysis, we identified the following reasons for avoiding brittle fracture at the headed ends: (1) Precipitation hardening increases the strength around the boundary between the straight and headed (tapered) portions, where stress concentration takes place. (2) The strength of the straight portion does not increase significantly up to the ductile fracture if its grain orientation is close to 〈0 0 1〉.

Prediction of railway wheel wear and its influence on the vehicle dynamics in a specific operating sector of Indian railways network

In railway operations, wear prediction due to wheel-rail interaction is crucial for different aspects such as running stability, passenger safety and comfort, life cycle optimization and maintenance scheduling. In this article, wheel wear is estimated through co-simulation between multi-body vehicle dynamic model developed in Adams™ VI-Rail™ software and wear evolution model developed in MATLAB® software. Semi-Hertzian/STRIPES approach and modified Kalker's FASTSIM approach are used for calculating normal and tangential stresses, respectively. The contact patch obtained from dynamic analysis is discretized into strips and variations of contact angle and spin for each strip, although small, are taken into account. Archard's wear formulation is applied for each strip within the contact patch. The wheel profiles are smoothened and are updated at intervals for further dynamic analysis. This way, the outputs from dynamic analysis (contact patches, creep forces, etc.) are input to the wear evolution model and the outputs from the wear evolution model (worn wheel profiles) are fed to the dynamic analysis. The wear at the flange and tread portions of the wheels during the normal service condition in an operational track sector between two major rail stations in India, containing curved and straight portions, speed variation (acceleration and braking), and corresponding track configurations (super-elevation, irregularities, etc.) are estimated and the wheel re-profiling schedule was obtained. In addition, the influences of the various stages of wheel wear on the dynamic responses such as curving performance, critical speed and ride comfort of the railway vehicle on the simulated test track are evaluated to justify the maintenance/wheel re-profiling schedule.

Estimation of Maximum Pressure Stress Intensity in a Welding Tee

The required thickness of welding tees is neither specified in ASME (2012, “Factory-Made Wrought Buttwelding Fittings,” American Society of Mechanical Engineers, New York, Standard No. B16.9-2012) nor is a clear calculation method provided in codes such as ASME (2016, “Process Piping,” American Society of Mechanical Engineers, New York, Standard No. B31.3-2016). This can lead to uncertainty regarding the pressure capacity of a tee fitting, particularly one that has suffered from erosion or corrosion. Code methods including area replacement (ASME, 2016, “Process Piping,” American Society of Mechanical Engineers, New York, Standard No. B31.3-2016) or pressure-area (ASME, 2015, “Boiler and Pressure Vessel Code Section VIII Division 2,” American Society of Mechanical Engineers, New York, Standard No. BPVC-VIII-2-2015; BSI, 2014, “Unfired Pressure Vessels Part 3: Design,” BSI, London, UK, Standard No. BS EN 13445-3) do not directly account for the effect which the curvature of the crotch region may have on the stress state in the tee. The approach adopted in this work is to liken the geometry of the tee crotch to the intrados of a torus or pipe bend. The shell theory applicable to the torus is adapted for the tee in order to derive a relationship for circumferential membrane stress. An equivalent tube radius is assigned by determining the local radius of shell curvature in the plane passing through the crotch center of the curvature. The actual stresses in the tee crotch are significantly reduced by the adjoining straight portions. This effect is difficult to quantify theoretically and has thus been investigated by means of finite element analysis (FEA)-based assessments. An empirical relationship was then established providing a conservative correlation between the theoretical stresses and the program calculated local stress intensities.

Quantitative transportation assessment in simulated curved canals after large apical preparations

Aim: To evaluate the ability of rotary (ProTaper Universal [PTU] and ProTaper Next [PTN]), reciprocating (Reciproc [R] and WaveOne [WO]) and adaptive (Twisted File Adaptive [TFA]) systems in maintaining the original canal profile in straight and curved parts after apical preparations up to size 40. Methods: Resin blocks with simulated curved canals were randomly assigned to five groups: PTU, PTN, R, WO and TFA. Images were captured from each block before and after canal preparation (n=10). Assessment of canal transportation was obtained for the straight and curved parts of the canal. ANOVA followed by Tukey’s test was used (α = 5%). Results: Transportation values were increased at the curved part (P = .00). For both canal levels, TFA system induced the lowest mean of canal transportation followed by PTN, R, WO and PTU systems. At the straight portion, transportation for R and TFA systems were similar (P > .05), and these values were significantly lower than for WO, PTN and PTU (P = .00). At the curved portion, TFA resulted in less canal transportation, followed by PTN, R, WO and PTU systems (P = .00). Conclusions: TFA system produced less canal transportation than other systems tested during large apical preparations.

Effects of Stacked Layers and Stacked Configurations on Wire Sweep and Wire Sag of Advanced Overhang/Pyramid Stacked Packages

Overhang and/or pyramid stacked packages are the trend in the semiconductor industry. As the stacked layers increase drastically, the wire sweep and wire sag problems become more and more serious. Based on some types of frequently used stacked configurations, their corresponding wire sweep and wire sag stiffness and deflections are investigated for extra-high stacked layers. Two typical profiles of Q_loop and S_loop wire bonds are included in this study. However, wire sweep and wire sag have to be considered in two different design aspects. For wire sweep, we have the conclusion that the maximum wire sweep deflections always occur near the central segment of a wire bond. As for the wire sag, the maximum wire sag may take place in the center region of the straight portion of a wire bond. The result shows that the deflections of wire sag can be reduced significantly by simply shifting the position of the kink or bend created within a wire bond. Finally, we have concluded that a stacked configuration with smallest bond span may be the preferred selection for the concerns of wire sweep and wire sag issues.

Redescription ofAllobenedenia dischizosepta(Suriano, 1975) n. comb. (Monogenoidea: Capsalidae: Trochopodinae) from the Gills of Argentine Sea Basses (Acanthistius) in the Southwestern Atlantic Ocean

We herein redescribe Allobenedenia dischizosepta (Suriano, 1975) n. comb. (Monogenoidea: Capsalidae) based on light microscopic analysis of the holotype and 18 paratypes from the gill of Acanthistius brasilianus (Cuvier, 1828) (Perciformes: Serranidae) along with light and scanning electron microscopy of 25 newly collected specimens from the gill of Acanthistius patachonicus (Jenyns, 1842) (new host record) in the southwestern Atlantic Ocean off Argentina. Contradicting the original description of this species and its generic diagnosis, all specimens had 5 loculi (2 anterior plus 3 posterior loculi) plus 5 corresponding haptoral septa only (central loculus absent). The original description of this species erroneously specified 6 loculi, including 2 small anterolateral loculi. Because A. dischizosepta was the type species for Tetrasepta Suriano, 1975 and because it fits the diagnosis of Allobenedenia Yamaguti, 1963, the genus therefore is regarded a junior synonym of Allobenedenia. Allobenedenia dischizosepta differs from its congeners by lacking a haptoral peduncle as well as by having 5 haptoral loculi, accessory sclerites that lack a conspicuous dorsal protuberance and that are weakly bifid, by posssesing robust anterior hamuli that are strongly recurved for half of their total length, by having a male accessory gland reservoir in the extreme posterior portion of the penis sac and lateral to the vitelline reservoir abutting the ovary, and by the presence of a straight (not coiled) proximal portion of the ejaculatory duct within the penis sac.

Secondary motion in three-dimensional branching networks

A major aim of the present work is to understand and thoroughly document the generation, the three-dimensional distribution, and the evolution of the secondary motion as the fluid progresses downstream through a branched network. Six generations (G0-G5) of branches (involving 63 straight portions and 31 bifurcation modules) are computed in one go; such computational challenges are rarely taken in the literature. More than 30 × 106 computational elements are employed for high precision of computed results and fine quality of the flow visualization diagrams. The study of co-planar vis-à-vis non-planar space-filling configurations establishes a quantitative evaluation of the dependence of the fluid dynamics on the three-dimensional arrangement of the same individual branches. As compared to the secondary motion in a simple curved pipe, three distinctive features, viz., the change of shape and size of the flow-cross-section, the division of non-uniform primary flow in a bifurcation module, and repeated switchover from clockwise to anticlockwise curvature and vice versa in the flow path, make the present situation more complex. It is shown that the straight portions in the network, in general, attenuate the secondary motion, while the three-dimensionally complex bifurcation modules generate secondary motion and may alter the number, arrangement, and structure of vortices. A comprehensive picture of the evolution of quantitative flow visualizations of the secondary motion is achieved by constructing contours of secondary velocity [Formula: see text], streamwise vorticity [Formula: see text], and [Formula: see text] iso-surfaces. It is demonstrated, for example, that for in-plane configuration, the vortices on any plane appear in pair (i.e., for each clockwise rotating vortex, there is an otherwise identical anticlockwise vortex), whereas the vortices on a plane for the out-of-plane configuration may be dissimilar, and there may even be an odd number of vortices. We have formulated three new parameters (ES/P , [Formula: see text], and [Formula: see text]) for a quantitative description of the overall features of the secondary flow field. [Formula: see text] represents a non-uniformity index of the secondary flow in an individual branch, ES/P represents the mass-flow-averaged relative kinetic energy of the secondary motion in an individual branch, and [Formula: see text] provides a measure of the non-uniformity of the secondary flow between various branches of the same generation Gn. The repeated enhancement of the secondary kinetic energy in the bifurcation modules is responsible for the occurrence of significant values of ES/P even in generation G5. For both configurations, it is found that for any bifurcation module, the value of ES/P is greater in that daughter branch in which the mass-flow rate is greater. Even though the various contour plots of the complex secondary flow structure appear visually very different from one another, the values of [Formula: see text] are found to lie within a small range ([Formula: see text]) for the six-generation networks studied. It is shown that [Formula: see text] grows as the generation number Gn increases. It is established that the out-of-plane configuration, in general, creates more secondary kinetic energy (higher ES/P ), a similar level of non-uniformity in the secondary flow in an individual branch (similar [Formula: see text]), and a significantly lower level of non-uniformity in the distribution of secondary motion among various branches of the same generation (much lower [Formula: see text]), as compared to the in-plane arrangement of the same branches.

A Normalized Transfer Matrix Method for the Free Vibration of Stepped Beams: Comparison with Experimental and FE(3D) Methods

The exact solution for multistepped Timoshenko beam is derived using a set of fundamental solutions. This set of solutions is derived to normalize the solution at the origin of the coordinates. The start, end, and intermediate boundary conditions involve concentrated masses and linear and rotational elastic supports. The beam start, end, and intermediate equations are assembled using the present normalized transfer matrix (NTM). The advantage of this method is that it is quicker than the standard method because the size of the complete system coefficient matrix is 4 × 4. In addition, during the assembly of this matrix, there are no inverse matrix steps required. The validity of this method is tested by comparing the results of the current method with the literature. Then the validity of the exact stepped analysis is checked using experimental and FE(3D) methods. The experimental results for stepped beams with single step and two steps, for sixteen different test samples, are in excellent agreement with those of the three-dimensional finite element FE(3D). The comparison between the NTM method and the finite element method results shows that the modal percentage deviation is increased when a beam step location coincides with a peak point in the mode shape. Meanwhile, the deviation decreases when a beam step location coincides with a straight portion in the mode shape.

Comparison of the Shaping Ability of WaveOne Reciprocating Files with or without Glide Path in Simulated Curved S-shaped Root Canals.

Objectives:The aim was to compare the shaping ability of WaveOne reciprocating files with or without glide path in simulated curved S-shaped root canals.Materials and Methods:Forty ISO #15, 0.02 taper, clear resin Endo Training Bloc-S blocks were studied. The simulated curved S-shaped canals were dyed using ink, preinstrumentation images were scanned, and resin blocks were prepared and divided into Group A: PathFile and WaveOne and Group B: WaveOne. All canals were postoperatively scanned. Pre- and postoperative images were superimposed and evaluated at 12 defined measuring points. The efficacy of the systems was compared based on the amount and direction of canal transportation, centering ability, amount of material removed, and presence of canal aberrations. Mann–Whitney U-test and independent t-test were used for statistical comparison.Results:Both systems produced transportation at all levels and straightened the curved S-shaped canals. No significant differences in the amount and direction of transportation and amount of material removed were observed between the groups at each level (P > 0.05). However, Group A had significantly greater centering ability at the coronal straight zone (P = 0.018) and apical curvature (P = 0.014) levels than did Group B. Moreover, Group B showed more canal aberrations than did Group A.Conclusion:Within the limitations of the present study, the creation of a glide path with the PathFile system improved the centering ability of the WaveOne reciprocating file in the apical and straight coronal portions of the simulated curved S-shaped root canals and reduced the incidence of canal aberrations.

Finding order in complexity: A study of the fluid dynamics in a three-dimensional branching network

The complex fluid dynamics associated with the flow in three-dimensional dichotomously branching networks is investigated. The flow physics described here is generic, though the particular flow geometry employed represents a model human bronchial tree. Up to six generations of branches (involving 63 straight portions and 31 bifurcation modules) are computed in one go; such computational challenges are rarely taken in the literature. In the present study, two branching configurations are considered side by side: the most widely studied in-plane configuration in which the centrelines of all generations lie on the same plane, and the 90∘ out-of-plane configuration in which the centreline of each generation is rotated with respect to its grandmother generation following a systematic methodology to form a space-filling three-dimensional structure. The paper develops a physical understanding of the fluid dynamics of branching networks and its dependence on the configuration (in-plane versus out-of-plane) and the extent (four, five, or six generations) of the network under consideration. The study of co-planar vis-à-vis non-planar configurations establishes a quantitative evaluation of the dependence of the fluid dynamics on the three-dimensional arrangement of the same individual branches. It is shown that apparent symmetry in the geometry of any two branches does not automatically imply symmetry in the flow field in those two branches. With the help of velocity contours, pressure contours, and distribution of mass flow in each branch, a qualitative and quantitative study is performed on the nature and evolution of flow asymmetry. The computations show that the degree of mass-flow asymmetry is smaller for the out-of-plane configuration (which is a more realistic model of a human bronchial tree) as compared to that for the in-plane configuration. The mass-flow asymmetry grows in each successive generation (starting from generation G2 for in-plane and G3 for out-of-plane configurations). In addition to mass-flow distribution, other types of asymmetries in the flow field are also analysed. It is established that, in spite of the complexity of the flow solutions, there also exists a systematic order such that it is possible to ascertain the flow field in all branches of a particular generation by determining the flow field in some systematically selected branches of that generation, indicating a possible route to the saving of computational resource and time.

THE SYSTEMATICS OF STRONG LENS MODELING QUANTIFIED: THE EFFECTS OF CONSTRAINT SELECTION AND REDSHIFT INFORMATION ON MAGNIFICATION, MASS, AND MULTIPLE IMAGE PREDICTABILITY

ABSTRACT Until now, systematic errors in strong gravitational lens modeling have been acknowledged but have never been fully quantified. Here, we launch an investigation into the systematics induced by constraint selection. We model the simulated cluster Ares 362 times using random selections of image systems with and without spectroscopic redshifts and quantify the systematics using several diagnostics: image predictability, accuracy of model-predicted redshifts, enclosed mass, and magnification. We find that for models with >15 image systems, the image plane rms does not decrease significantly when more systems are added; however, the rms values quoted in the literature may be misleading as to the ability of a model to predict new multiple images. The mass is well constrained near the Einstein radius in all cases, and systematic error drops to <2% for models using >10 image systems. Magnification errors are smallest along the straight portions of the critical curve, and the value of the magnification is systematically lower near curved portions. For >15 systems, the systematic error on magnification is ∼2%. We report no trend in magnification error with the fraction of spectroscopic image systems when selecting constraints at random; however, when using the same selection of constraints, increasing this fraction up to ∼0.5 will increase model accuracy. The results suggest that the selection of constraints, rather than quantity alone, determines the accuracy of the magnification. We note that spectroscopic follow-up of at least a few image systems is crucial because models without any spectroscopic redshifts are inaccurate across all of our diagnostics.

Cut Surface Features in Various Die-Cutting Processes

Currently, the shaped parts combined with straight, concave, and convex portions are increasingly fabricated. To produce the straight portion, the shearing theory is usually applied. As well as, to produce the concave and convex portions, the punching and blanking theories are usually applied. However, with the same die-cutting process parameters, the comparison of cut surface features of straight, concave, and convex portions has not been investigated yet. Therefore, in the present research, the comparison of the cut surface features in various die-cutting processes, including shearing, blanking, and punching processes are investigated. The finite element method (FEM) was used as a tool to investigate these cut surface features. The cut surface features were investigated and clearly identified via the changes of the stress distribution analyses. The results elucidated that with the same die-cutting process parameters, the different cut surface features were obtained. Specifically, the crack formations were easily generated in the case of blanking process, following by the shearing and punching processes, respectively. Therefore, the smooth cut surface was smallest in the case of blanking process, following by the shearing and punching processes, respectively. The laboratory experiments were carried out to verify the accuracy of the FEM simulation results. Based on the cut surface features, the FEM simulation results showed good agreement with the experimental results in terms of the cut surface features. Therefore, to design the die-cutting process parameters to meet the product requirements of complicated shapes, the understanding on these working process parameters being upon the shaped parts is necessarily.

Stiffness comparison of mushroom and straight SS and TMA lingual archwires.

BackgroundThe aim of this study is to investigate the relative stiffness of straight and mushroom lingual archwires of different diameters, cross sections and alloys, plotting their load/deflection graphs and using a modified three-point bending test.MethodsFujita’s mushroom archwires and straight lingual archwires of different diameters, cross sections and alloys were derived by a virtual set-up of an equal malocclusion and were cut at their straight distal portion. These distal portions were tested using a modified three-point bending test by an Instron 4467 dynamometer and the forces, were exerted at 1-mm deflection and were compared on each resulting load/deflection curve by means of ANOVA (p < 0.05).ResultsAll upper lingual mushroom wires exerted significantly lower forces than the straight wire. Lower mushroom archwires were stiffer than their upper counterparts, which were longer and featured inset bends. In the lower arch, similar levels of forces were recorded for the two types of wire. Load-deflection curves were higher for the straight wires, and stiffness increased proportionally with their diameter.ConclusionsThe stiffness of an archwire is a function of its diameter, length and the alloy it is made from. In lower lingual wires, there is little difference in stiffness between mushroom and straight wires, but in upper wires, the straight version is considerably stiffer. The greater bearing effect exhibited by the straight wire in the working and finishing phases makes it less susceptible to bowing effect and therefore preferable for sliding mechanics during en masse retraction, particularly in the upper arch.