End Shape Research Articles

The Effect of Passive Base Ventilation on the Aerodynamic Drag of a Generic SUV Vehicle

Sports Utility Vehicles (SUVs) typically have a blunt rear end shape (for design and practicality), however this is not beneficial for aerodynamic drag. Drag can be reduced by a number of passive and active methods such as tapering and blowing into the base. In an effort to combine these effects and to reduce the drag of a visually square geometry slots have been introduced in the upper side and roof trailing edges of a squareback geometry, to take air from the freestream and passively injects it into the base of the vehicle to effectively create a tapered body. This investigation has been conducted in the Loughborough University’s Large Wind Tunnel with the ¼ scale generic SUV model. The basic aerodynamic effect of a range of body tapers and straight slots have been assessed for 0° yaw. This includes force and pressure measurements for most configurations. The slots generate useful, but small, drag reductions with the best configurations giving reductions in drag coefficient (Cd) of approximately 0.01, whereas the best taper configurations reduce Cd by close to 0.035. The slots also have a tendency to modify the lift.

Wind pressures on different roof shapes of a finite height circular cylinder

The effects of finite cylinder free end shape on the mean and fluctuating wind pressures were investigated experimentally and numerically by using three different roof shapes: flat, conical and hemispherical. The pressure distributions on the roofs and the side walls of the finite cylinders partially immersed in a simulated atmospheric boundary layer have been obtained for three different roof shapes. Realizable <TEX>$k-{\varepsilon}$</TEX> turbulence model was used for numerical simulations. Change in roof shapes has caused significant differences on the pressure distributions. When compared the pressure distributions on the different roofs, it is seen from the results that hemispherical roof has the most critical pressure field among the others. It is found a good agreement between numerical and experimental results.

Study of compound hydroforming of profiled tubes

Abstract This study is to propose a loading scheme combined with die crushing and axial feeding to manufacture a profiled tube with different end shapes. Carbon steel of SPFC590Y is used as the tube material. The flow stresses of SPFC590Y steel tube at room temperature are obtained by tensile tests. A finite element software DYNAFORM is adopted to simulate the plastic deformation of the profiled tube during hydroforming and crushing processes. The effects of forming schedules on the formability and thickness distributions of the products are discussed. Finally, a profiled die set and a rectangular punch head are designed and manufactured, and experiments of hydroforming and crushing processes of ERW steel tubes are conducted using a self-designed hydroforming machine. Experimental results of product shapes and thickness distributions are compared with the simulation results to verify the validity of the finite element modelling and the designed loading schedules.

Screening for bacterial wilt resistance of bell pepper under sick field conditions and morphological characterization

The present investigation was carried out on 46 genotypes of bell pepper to study bacterial wilt resistant genotypes and their morphological characterization under natural sick field conditions at Palampur aiming at the development of high-yielding, bacterial wilt (Ralstonia solanacearum) resistant lines of bell pepper. Based upon the mean performance, genotypes DPCBWR-14-39, DPCBWR-14-36, DPCBWR-14-31, DPCBWR-14-35, DPCBWR-14-11, DPCBWR-14-7 and DPCBWR-14-29 were found to be top yielders and resistant to bacterial wilt disease. All the genotypes taken for study were found to be resistant and moderately resistant to bacterial wilt disease except DPCBWR-14-22, DPCBWR-14-23, DPCBWR-14-34, DPCBWR-14-37 and DPCBWR14–43. Bell pepper germplasm contained sufficient genetic variability and can be used for crop improvement. Coincidently, among the top five high yielding progenies most showed green group (GG), blocky fruit shape, pendent fruit position, cordate fruit shape at pedicel end and sunken fruit shape at blossom end. Thus, these genotypes can be further used for breeding programmes and can be directly used after multi-location testing as these possess inherent ability to high yielding alongwith bacterial wilt resistance.

Bovine mastitis: prevalence, risk factors and isolation of Staphylococcus aureus in dairy herds at Hawassa milk shed, South Ethiopia

BackgroundMastitis is a disease of major economic importance in dairy industry worldwide. It is of particular concern in developing countries like Ethiopia, where milk and milk products are scarce. The objectives of the study were to estimate the prevalence of mastitis, identify the cow-and herd-level potential risk factors and isolate Staphylococcus aureus, one of etiological agents for contagious mastitis, from cows positive for mastitis. A total of 529 lactating cows selected randomly from 95 herds were screened by California mastitis test (CMT) for sub-clinical mastitis. Also 172 milk samples collected from CMT positive cows were cultured for isolation of S. aureus.ResultsBased on CMT result and clinical examination, the prevalence of mastitis at herd-level was 74.7% (95% CI: 64.5, 82.8). The corresponding cow-level prevalence was 62.6% (95% CI: 58.3, 66.7), of which 59.2 and 3.4% were sub-clinical and clinical mastitis cases, respectively. S. aureus was isolated from 51.2% of the milk samples cultured and 73.2% of the herds affected with mastitis. In the multivariable logistic regression model, the herd-level factors significantly associated (p < 0.05) with the presence of mastitis were herd size, bedding material, and milking mastitic cows last, while at cow-level, breed, parity, stage of lactation, udder and leg hygiene, and teat end shape were noted to have a significant effect on mastitis occurrence.ConclusionThe very high prevalence of mastitis, more importantly the sub-clinical one, in the herds examined revealed the huge potential economic loss the sector suffers. Perhaps this was attributed to lack of implementation of the routine mastitis prevention and control practices by all of the herd owners. The findings of this study warrants the need for strategic approach including dairy extension that focus on enhancing dairy farmers’ awareness and practice of hygienic milking, regular screening for sub-clinical mastitis, dry cow therapy and culling of chronically infected cows.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-016-0905-3) contains supplementary material, which is available to authorized users.

Agromorphological genetic diversity of Spanish traditional melons

The variability of 62 Spanish landraces (and two hybrids used as reference) was described by analysing 39 morphological traits and eight SSR makers. Results showed that 81% of the examined genetic pool belonged to the inodorus type. Spanish traditional melons presented fruits from flattened and globular shapes to elliptical. Rind colour varied from pale green, almost white and yellow to dark green and almost black. Rind texture varied from smooth to intensely wrinkled. Spanish landraces also had larger fruits (average fruit weight ~2.6 kg) and longer vegetative cycles (117 days to maturity) compared to landraces from other geographical origins. Farmers seem to have focused on selection towards large fruits, which usually requires the longest production cycles. Fruit colour, size and shape seemed to have been determinant in varietal selection. Hierarchical clustering resulted in two main groups (climacteric and non-climacteric). The largest group was composed of 60 accessions of non-climacteric types, which includes the most demanded by national markets, ‘Piel de Sapo’, which fruits were characterized by an ovate or elliptical shape, a green rind, big spots and stains distributed over the whole fruit, a rounded blossom end shape and a very pointed stem end shape. The study demonstrates that the Spanish genetic pool is much more diverse. Wide variability was found in a geographical area with vast historical importance in melon farming. These evaluations has allowed the identification of several uniform groups of non-climacteric cultivars (‘Piel de Sapo’, ‘Mochuelo’, ‘Tendral’, Yellow/White, Winter and Black groups) and a set of highly variable climacteric ones. However, many accessions with singular properties remain unclassified, demonstrating the morphological variability of the studied collection. Melons in Spain have wide variability together with a vast historical importance on farms. Some fruit types, or at least some morphological characters reflected by painters during centuries, have reached the present. The present study confirmed the need to preserve these irreplaceable genetic resources and continue their study and evaluation for valuable traits which could enhance farmer’s opportunities for entering new markets.

A slender drop in a nonlinear extensional flow

The deformation of a slender drop in a nonlinear axisymmetric extensional and creeping flow has been theoretically studied. This problem, which was first suggested by Sherwood (J. Fluid Mech., vol. 144, 1984, pp. 281–295), is being revisited, and new results are presented. The problem is governed by three dimensionless parameters: the capillary number ($\mathit{Ca}\gg 1$), the viscosity ratio ($\unicode[STIX]{x1D706}\ll 1$), and the nonlinear intensity of the flow ($E\ll 1$). Contrary to linear extensional flow ($E=0$), where the local radius of the drop decreases monotonically (in the positive $z$ direction), in a nonlinear extensional flow ($E\neq 0$), two possible steady shapes exist: steady shapes (stable or unstable) with the local radius decreasing monotonically, and steady shapes (unstable) where the local radius of the drop has a local maximum, besides the one at the centre of the drop. Similar to linear extensional flow, the addition of nonlinear extensional effects does not change the end shape of the steady drop, which has pointed ends. A stability analysis has been done to distinguish between stable and unstable steady shapes and to determine the breakup point. Time-dependent studies reveal three types of breakup mechanism: a centre pinching mode, indefinite elongation, and a mechanism that remind us of tip-streaming, where a cusp is developed at the end of the drop.

Large scale fabrication of nitrogen vacancy-embedded diamond nanostructures for single-photon source applications**Project supported by the National Key Research and Development Plan of China (Grant No. 2016YFA0200402), the National Natural Science Foundation of China (Grants Nos. 11574369, 11574368, 91323304, 11174362, and 51272278), and the FP7 Marie Curie Action (project No. 295208) sponsored by the European Commission.

Some color centers in diamond can serve as quantum bits which can be manipulated with microwave pulses and read out with laser, even at room temperature. However, the photon collection efficiency of bulk diamond is greatly reduced by refraction at the diamond/air interface. To address this issue, we fabricated arrays of diamond nanostructures, differing in both diameter and top end shape, with HSQ and Cr as the etching mask materials, aiming toward large scale fabrication of single-photon sources with enhanced collection efficiency made of nitrogen vacancy (NV) embedded diamond. With a mixture of O2 and CHF3 gas plasma, diamond pillars with diameters down to 45 nm were obtained. The top end shape evolution has been represented with a simple model. The tests of size dependent single-photon properties confirmed an improved single-photon collection efficiency enhancement, larger than tenfold, and a mild decrease of decoherence time with decreasing pillar diameter was observed as expected. These results provide useful information for future applications of nanostructured diamond as a single-photon source.

Monotonic and hysteretic pullout behavior of superelastic SMA fibers with different anchorages

Abstract The aim of this study is to assess the pullout resistance of superelastic shape memory alloy (SMA) short fibers with different end shapes, which provide different anchoring actions, through monotonic and hysteretic pullout tests. For this study, NiTi superelastic SMA wire with a diameter of 1.0 mm was prepared and cut by a length of 40 mm to make SMA short fibers. Four types of SMA fibers with different end shapes were manufactured namely: 1) straight end shape, 2) crimped end, 3) bended end with L-shape, and 4) spearhead end. The straight end-shaped fiber was one without any anchoring action on the end part. The crimped fiber had grooves on the two sides manufactured by crimping an end part of 5 mm. The end-bended fiber had an L-shaped end with a 30° bending angle. The fiber with a spearhead was manufactured by pressing the end part of 5 mm. The pullout tests of the fibers from the mortar matrix were first monotonically conducted with displacement control, and the hysteretic pullout behavior was obtained by 4 cyclic loadings. The L-shaped fibers increased the pullout resistance significantly compared with the straight and crimped fibers. However, they did not reach the upper plateau stress of the SMA fiber to induce state transformation. Only the fibers with a spearhead end exceeded the stress for the state transformation because they provided sufficient anchoring resistance due to the spearhead. The maximum pullout resistance of the spearhead fiber was 3.74 times that of the L-shaped fiber. Moreover, they showed flag-shaped behavior during the hysteretic tests.

Impact of udder and teat morphometry on udder health in Tharparkar cows under climatic condition of hot arid region of Thar Desert.

Prevention of subclinical mastitis (SCM) is an important tool for sustainable dairying and implementing higher production level in animals. The present investigation involved a total of 397 quarters of milk examination of 105 indigenous Tharparkar cows at Livestock Research Centre, Chandan located in the Jaisalmer district of Rajasthan in Thar Desert to study the impact of udder and teat morphometry on udder health. Udder health was examined by somatic cell count to check the status of subclinical mastitis while udder and teat morphometry of 90 udder and 386 quarters, i.e., udder shape and depth, teat end shape, teat length, and teat diameter were examined at individual animal level and quarter level. Data were collected from the record register maintained at the farm and data evaluated by parity (no. of lactation) and stage of lactation. On analysis of variance, result revealed the significantly (P < 0.05) higher incidence of SCM was for pendulous shape udder in respect of regular udder, as well as for inverted and flat teat end shape in respect of pointed teat end shape. Large teat length and upper depth animals had significantly (P < 0.05) more incidence of SCM as compared to small and medium teat length and udder depth group, respectively. Thick teat diameter group animals were significantly (P < 0.01) more prone to infection as compared to medium and thin teat diameter group animals. So, it can be concluded that selection for optimum udder and teat morphometry in breeding program may help to reduce susceptibility for intramammary infections in Tharparkar cows. Microbiological study of milk samples could be helpful in the nearby future for identification of subclinical mastitis.

Genetic Diversity, Population Structure, and Heritability of Fruit Traits in Capsicum annuum.

Cultivated pepper (Capsicum annuum) is a phenotypically diverse species grown throughout the world. Wild and landrace peppers are typically small-fruited and pungent, but contain many important traits such as insect and disease resistance. Cultivated peppers vary dramatically in size, shape, pungency, and color, and often lack resistance traits. Fruit characteristics (e.g. shape and pericarp thickness) are major determinants for cultivar selection, and their association with disease susceptibility can reduce breeding efficacy. This study evaluated a diverse collection of peppers for mature fruit phenotypic traits, correlation among fruit traits and Phytophthora fruit rot resistance, genetic diversity, population structure, and trait broad sense heritability. Significant differences within all fruit phenotype categories were detected among pepper lines. Fruit from Europe had the thickest pericarp, and fruit from Ecuador had the thinnest. For fruit shape index, fruit from Africa had the highest index, while fruit from Europe had the lowest. Five genetic clusters were detected in the pepper population and were significantly associated with fruit thickness, end shape, and fruit shape index. The genetic differentiation between clusters ranged from little to very great differentiation when grouped by the predefined categories. Broad sense heritability for fruit traits ranged from 0.56 (shoulder height) to 0.98 (pericarp thickness). When correlations among fruit phenotypes and fruit disease were evaluated, fruit shape index was negatively correlated with pericarp thickness, and positively correlated with fruit perimeter. Pepper fruit pericarp, perimeter, and width had a slight positive correlation with Phytophthora fruit rot, whereas fruit shape index had a slight negative correlation.

Property and Shape Modulation of Carbon Fibers Using Lasers.

An exciting challenge is to create unduloid-reinforcing fibers with tailored dimensions to produce synthetic composites with improved toughness and increased ductility. Continuous carbon fibers, the state-of-the-art reinforcement for structural composites, were modified via controlled laser irradiation to result in expanded outwardly tapered regions, as well as fibers with Q-tip (cotton-bud) end shapes. A pulsed laser treatment was used to introduce damage at the single carbon fiber level, creating expanded regions at predetermined points along the lengths of continuous carbon fibers, while maintaining much of their stiffness. The range of produced shapes was quantified and correlated to single fiber tensile properties. Mapped Raman spectroscopy was used to elucidate the local compositional and structural changes. Irradiation conditions were adjusted to create a swollen weakened region, such that fiber failure occurred in the laser treated region producing two fiber ends with outwardly tapered ends. Loading the tapered fibers allows for viscoelastic energy dissipation during fiber pull-out by enhanced friction as the fibers plough through a matrix. In these tapered fibers, diameters were locally increased up to 53%, forming outward taper angles of up to 1.8°. The tensile strength and strain to failure of the modified fibers were significantly reduced, by 75% and 55%, respectively, ensuring localization of the break in the expanded region; however, the fiber stiffness was only reduced by 17%. Using harsher irradiation conditions, carbon fibers were completely cut, resulting in cotton-bud fiber end shapes. Single fiber pull-out tests performed using these fibers revealed a 6.75-fold increase in work of pull-out compared to pristine carbon fibers. Controlled laser irradiation is a route to modify the shape of continuous carbon fibers along their lengths, as well as to cut them into controlled lengths leaving tapered or cotton-bud shapes.

Influence of Manufacturing Accuracy on Magnetic Field Distribution in Magnet for HTS Rotating Gantry

Because of its high curative effects and low burden on patients, carbon ion cancer therapy is becoming more widely used. The accelerated carbon ions are delivered to patients via electromagnets on a rotating gantry. One advantage of a rotating gantry is that a tumor can be irradiated with carbon ions from any direction without changing the posture of the patient. On the other hand, because of the high magnetic rigidity of carbon ions, rotating gantries for carbon cancer therapy are about three times heavier than those for proton cancer therapy, according to our estimation. Use of high-temperature superconducting (HTS) magnets has been considered for reducing the size of the rotating gantry for carbon cancer therapy. For accurate irradiation, these HTS magnets must generate high-uniformity magnetic fields, and the shape of the HTS coils was designed by 3-D analysis to generate uniform magnetic fields. In our design, saddle-shaped HTS coils were used since they can efficiently generate a magnetic field. The conductor positions and the coil end shape were optimized to generate a uniform magnetic field. On the other hand, it was difficult to maintain the HTS conductor in the designed saddle shape because it has a tapelike shape and anisotropic flexibility in bending. In this paper, the winding accuracy of the fabricated HTS saddle-shaped coil was measured, and the influence of the measurement result on the magnetic field distribution was evaluated.

Prediction and control of pillow defect in single point incremental forming using numerical simulations

Pillows formed at the center of sheets in Single point incremental forming (SPIF) are fabrication defects which adversely affect the geometrical accuracy and formability of manufactured parts. This study is focused on using FEA as a tool to predict and control pillowing in SPIF by varying tool size and shape. 3D Finite element analysis (FEA) and experiments are carried out using annealed Aluminum 1050. From FEA, it is found out that the stress/strain state in the immediate vicinity of the forming tool in the transverse direction plays a determinant role on sheet pillowing. Furthermore, pillow height increases as compression in the sheet-plane increases. The nature of in-plane stresses in the transverse direction varies from compressive to tensile as the tool-end geometry is changed from spherical to flat. Additionally, the magnitude of corresponding in-plane stresses decreases as the tool radius increases. According to measurements from the FEA model, flat end tools and large radii both retard pillow formation. However, the influence of changing tool end shape from hemispherical to flat is observed to be more important than the effect of varying tool radius, because the deformation zone remains in tension in the transverse direction while forming with flat end tools. These findings are verified by conducting a set of experiments. A fair agreement between the FEM and empirical results show that FEM can be employed as a tool to predict and control the pillow defect in SPIF.

Qualitative Inheritance of External Fruit Traits in Watermelon

Genes for watermelon [Citrullus lanatus (Thunb.) Matsumura &amp; Nakai] fruit traits have been identified since the 1930s. We conducted a study of fruit traits including fruit stripe width, stripe color, rind color, fruit shape, and blossom end shape (concave vs. convex). Ten watermelon cultivars (inbred lines) were used as parents. Several new genes or alleles were discovered. A series of alleles at the g locus is proposed to explain the inheritance of fruit rind pattern: G (medium or dark solid green), gW (wide stripe), gM (medium stripe), gN (narrow stripe), and g (solid light green or gray). The dominance series is G &gt; gW &gt; gM &gt; gN &gt; g. Another series of alleles at the ob locus is proposed for the fruit shape: allele ObE for elongate fruit, which is the most dominant; allele ObR (not the same as the o gene for round) for the round fruit; and allele ob for oblong fruit, which is the most recessive. Gene csm is proposed for the clear stripe margin in the cultivar Red-N-Sweet and is recessive to the blurred stripe margin (Csm) in ‘Crimson Sweet’, ‘Allsweet’, and ‘Tendersweet Orange Flesh’.

Publisher’s Note: Effect on cross-polarization conversion by the end shape of eSRR in a multilayer metamaterial device

This PDF file contains the errata for “OE Vol. 55 Issue 04 Paper OE-2016-0328-ERR” for OE Vol. 55 Issue 04

Numerical Research of Film Boiling Heat Transfer Around a Vertical Short Cylinder With Flat or Hemispherical Ends

Film boiling is a heat transfer mechanism that might appear in different processes, such as cryogenics, metallurgical, and nuclear reactors during abnormal operating conditions, as happens during a loss of coolant accident. In this research, film boiling around a finite vertical cylinder was studied by means of computational fluid dynamics (CFD) simulations, considering six cases that include three different levels of surface temperature and two different shapes of the cylinder ends: flat and hemispherical ends. Volume of fluid (VOF) method for the treatment of multiphase flow was used, and a user-defined function was programed to consider the exchange of mass and energy between the phases. The simulations were performed with a vertical cylinder of 32 mm in diameter and 32 or 64 mm in high for flat ends or hemispherical ends, respectively, placed in a two-dimensional axisymmetric domain of 0.125 m × 0.25 m. Results obtained for the heat flux show a periodic fluctuating behavior in time as a consequence of periodical variations in the thickness of the vapor film around the cylinder. A wavy liquid–vapor interface is observed as is reported in the experimental works. The simulations results are compared with the experimental values reported in literature as well as with values obtained from correlations. The results show that the computational code used captures reasonably well the physics involved in the film boiling, being obtained that average heat flux to the case of hemispherical ends is 15.6% higher than for the case of flat ends, versus 15.2% showing experiments and 1.6% calculated combining correlations for the individual surfaces. It shows that use of correlations in this way is not appropriate in film boiling because it does not take into account the interactions between the different surfaces.

A Glial K/Cl Transporter Controls Neuronal Receptive Ending Shape by Chloride Inhibition of an rGC

Neurons receive input from the outside world or from other neurons through neuronal receptive endings (NREs). Glia envelop NREs to create specialized microenvironments; however, glial functions at these sites are poorly understood. Here, we report a molecular mechanism by which glia control NRE shape and associated animal behavior. The C.elegans AMsh glial cell ensheathes the NREs of12 neurons, including the thermosensory neuron AFD. KCC-3, a K/Cl transporter, localizes specifically to a glial microdomain surrounding AFD receptive ending microvilli, where it regulates K(+) and Cl(-) levels. Wefindthat Cl(-) ions function as direct inhibitorsofanNRE-localized receptor-guanylyl-cyclase, GCY-8, which synthesizes cyclic guanosine monophosphate (cGMP). High cGMP mediates the effects of glial KCC-3 on AFD shape by antagonizing the actinregulator WSP-1/NWASP. Components of this pathway are broadly expressed throughout the nervous system, suggesting that ionic regulation of theNRE microenvironment may be a conserved mechanism by which glia control neuron shape and function.

The effect on cross-polarization conversion by the end shape of electric split-ring resonators in a multilayer metamaterial device

The effect on cross-polarization conversion by the end shape of electric split-ring resonators in a multilayer metamaterial device

The effect on cross-polarization conversion by the end shape of electric split-ring resonators in a multilayer metamaterial device

Several types of multilayer metamaterial devices are studied to achieve cross-polarization conversion as well as subwavelength transmission enhancement. The surface current of three metamaterial layers reveals that the induced current around the apertures of the middle metal layer is the key to the physical mechanism. Furthermore, the simulated results show that the proposed devices have good performance on both the polarization conversion ratio and transmission rate. Lastly, a tunable cross-polarization conversion design is proposed and researched. These results can help to facilitate the development of high-sensitivity sensors and terahertz technology.