Concave Nose Research Articles

Shapes of the fastest fish and optimal underwater and floating hulls

A streamlined shape of the best swimmers removes the boundary-layer separation and ensures a laminar flow pattern. The fastest fish have a very sharp convex nose (rostrum), the purpose of which remains unclear. The bodies of revolution similar to their shapes are analyzed in steady underwater and floating motion. The sources and sinks were located on the axis of symmetry and above the water surface to estimate the pressure on the body and the vertical velocities on the water surface. It was shown that the flow patterns on a special shaped body with concave nose has no stagnation points and ensure small values of the water surface elevation. These fact allow diminishing the maximum pressure on the surface and wave drag. Special shapes with the sharp concave nose and negative pressure gradients on their surface could be parts of the low drag underwater and floating hulls.

Fastest Fish Shapes and Optimal Supercavitating and Hypersonic Bodies of Revolution

Background. The best swimmers have a streamlined shape that provides a flow pattern without boundary layer separation and delays the laminar-to-turbulent transition. Their shape itself could be the reason of small drag and high locomotion velocity. The fastest fish, e.g., sailfish, swordfish, black marlin, etc. have another feature of their shape – a very sharp nose – rostrum, the purpose of which remains unclear. Popular belief that the rostrum is used by these predators to pierce their prey is often disputed. Objective. In this study, we analyze the hydrodynamic aspects of the rostrum presence and the possible use of similar hulls for supercavitating underwater vehicles and fast penetration into water. We illustrate that shapes with the very sharp nose could be useful for hypersonic motion in order to eliminate overheating of the vehicle fuselage. Methods. We use the known exact solutions of the Euler equations for the incompressible fluid to simulate the pressure distribution on the bodies of revolution with a sharp nose. The slender body theory is used to simulate the supercavitation and the axisymmetric air flows at high Mach numbers. Results. Bodies of revolution with a rostrum similar to trunks of the fastest fish (sailfish, swordfish, black marlin) and corresponding pressure ant temperature coefficients were calculated. The proposed shapes ensure no stagnation points and no high pressures and temperatures on their noses at sub- and supersonic speeds both in water and air. The drag on such bodies of revolution was estimated for attached, supercavitating and supersonic flow patterns. Conclusions. A method of calculation of axisymmetric bodies without stagnation points on their surface was proposed. This peculiarity of the shape allows diminishing the maximum pressure and temperature on the nose without a significant increase in drag. Such shapes with the sharp concave nose could be recommended for high-speed attached and supercavitating bodies of revolution and for the hypersonic motion.

Physical characteristics of the Uyghurs: anthropometric data from Kashgar

Before the Sui and Tang Dynasties, the Mediterranean type of the European race had been the main ethnic type of the ancient inhabitants of Kashgar. After moving westward to Xinjiang, the Uyghurs of the North Asian Mongolian race started to have long-term integration with other ethnic groups and gradually formed the Uyghurs. At present, the ethnographic characteristics of Uyghur have been a concern for a while. In this study, 560 subjects (273 males and 287 females) were selected and measured using anthropometric methods in Kashgar, the region most representative of the Uyghurs. The study showed that Uyghur individuals have obvious Eurasian characteristics, with South Asian and North Asian features also being identified in this region. However, East Asian type features were rarer in the Uyghur. According to physical characteristics indexes, Kashgar Uyghur males and females are of medium height and heavier weight; with rounder, taller heads and narrower faces that are mesorrhine; they are also wider in chest and shoulder with relatively long trunks. Males have medium head breadth and leg length whereas females possess narrow head breadth and shorter leg length. Among the 13 ethnic groups in China, Uyghur males were found to have a medium nasal root length and extraocular angle as well as reduced Mongolian fold and concave nose. Meanwhile, it is common for Uyghur females to have a high external eye angle, medium concave nose and dorsal rate, a high round ear lobe rate and low nasal base upturn rate. The Uyghur in southern Xinjiang are closer to the East Asian type than the Uyghur in northern Xinjiang. The head and nose features of Uyghur in southern Xinjiang are more similar to those from Mongolia. In case of facial features, the northern Uyghur and Mongolian are relatively close. There is a high incidence of wrinkles on the upper eyelids presented in Uyghur adults, with some people having Mongolian folds, a higher possibility of outer corners than inner corners, and mostly brown eye color. Together this suggests that Uyghur adults have the basic characteristics of the Mongolian race. Uyghur and East Asian ethnic groups are relatively close in face breadth, head length, morphological facial height and head breadth. Due to the fact that Uyghur individuals have rounder and taller heads accompanied by relatively long upper bodies and short legs, they can be considered to have the basic characteristics of an Oriental population. Both the Asian Oriental ethnic group features and Eurasian population characteristics are found in the Uyghur group in terms of their physical type. Among the various types in East Asia, Uyghur adults are closer to the East Asian type, while having certain characteristics of the South Asian and North Asian type. The physical characteristics of the Uyghur may potentially reflect the historical process of multi-ethnic integration.

Investigation of a new sheet metal shear cutting tool design to increase the part quality by superposed compression stress

Nowadays, a major criterion for the quality of shear cut workpieces is characterised by a smooth final cutting surface. Normally, this surface only can be manufactured by using fine cutting or trimming technology. Major disadvantage of these processes is the complex tooling design caused by a double-acting press and corresponding tool layout. Content of this study is to investigate the impact of a new sheet metal cutting tool design, also called concave nosed punch design, to increase the clean-cut portion in conventional shear cutting. The investigation focuses on sheet metal materials DP600, DC03 and HC420LA with a thickness of 1mm. Using FEA-Software DEFORM 2D, the models of conventional cutting and cutting with new tool design were mapped by comparing cutting surface results and stress distribution in the shearing zone. The main criterion of the optimization of tool design focuses on an enlarged clean-cut area along the cutting surface compared to conventional shear cutting. New tool design shows in numerical investigation a significant increase of clear-cut surface up to 73% compared to conventional cutting surfaces disclosing 35% when using tools according to standard design rules. With the result of the punch optimization in the numerical investigation, two cutting punches with different web widths were manufactured and experimentally investigated. The focus of the experimental investigation was the comparison of the cutting characteristics of smooth cut portion and cutting burr. The influence of the cutting clearance between 5% and 15% on the clean cut portion and the burr was investigated. Metallurgical micrographs show a significant increase in the percentage of smooth cut portion when punching with the new cutting method presented here. For DC03, these concave nose punch design was able to achieve smooth cut percentages of up to 95%. However, using this new punch design, it is possible to sheet metal materials revealing a noticeably performed shearing surface quality.

Numerical investigation on the thermal protection mechanism for blunt body with forward-facing cavity

Numerical experiments are carried out using the standard hypersonic ballistic-type model (HB-2) to investigate the effect of forward-facing cavity on the aerodynamic heating. A general concept is proposed which utilizes the flow disturbances generated passively in the nosed subsonic region to weaken the detached shock wave. Several aspects are mainly studied, including shock shape and standoff distance, surface heat flux and pressure, flowfield feature and cooling mechanism. The numerical results indicate that shock strength and standoff distance increase with an increase in the L/D ratio of the cavity. Interestingly, a bulge structure of the detached shock associated with a deep cavity is observed for the first time. Local surface heat flux and pressure around the concave nose are much lower respectively than those at the stagnation point of the baseline model. In addition, both surface heat and pressure reductions are proportional to the L/D ratio. A negative heating phenomenon may occur in the vicinity of a sharp lip or on the base wall of a deep cavity. If the L/D ratio exceeds 0.7, the detached shock appears as a self-sustained oscillation which can be referred to as the cooling mechanism.

Influence of nose contours on aesthetic perception of maxillary incisor inclination in smiling facial profile of Indian subcontinent people

PurposeThis study was aimed to evaluate the perception of maxillary incisor inclination (MxI) on smiling facial profile with respect to various nose contours by orthodontists, general dentists and laypeople. Materials and methodsOne male and one female smiling facial profile photograph with a Class I occlusion on skeletal Class I jaw bases with normal profile were digitized. Each photograph was altered by changing the incisor inclination (+5°, +10°, −5°, −10°) and nose contour (straight, convex & concave) to obtain 15 photographs and were randomly distributed among the three groups to score the attractiveness using visual analogue scale. ResultsSignificant differences (P<0.05) were detected when each photograph's ratings were compared. Convex nose contour with any MxI was rated as aesthetically unattractive by orthodontists whereas in concave nose subjects up to 5° labial inclination was preferred (P value 0.4440). Among the dentists and laypeople group up to 10° of lingual inclination in convex nose subjects and 5° of both labial and lingual inclinations in concave nose subjects were rated as attractive. ConclusionChange in the nose contour showed a statistically significant change in the aesthetic perception of maxillary incisor inclination among all the three groups.

On the impact of a concave nosed axisymmetric body on a free surface

We report on an experimental study of the vertical impact of a concave nosed axisymmetric body on a free surface. Previous studies have shown that bodies with a convex nose, like a sphere, produce a well defined splash with a relatively large cavity behind the model. In contrast, we find that with a concave nose, there is hardly a splash and the cavity extent is greatly reduced. This may be explained by the fact that in the concave nosed case, the initial impact is between a confined air pocket and the free surface unlike in the convex nosed case. From measurements of the unsteady pressure in the concave nose portion, we show that in this case, the maximum pressures are significantly lower than the classically expected “water hammer” pressures and also lower than those generally measured on other geometries. Thus, the presence of an air pocket in the case of a concave nosed body adds an interesting dimension to the classical problem of impact of solid bodies on to a free surface.

Streamlining of Bridge Piers as Scour Countermeasures

Pier streamlining is proposed as a flow-altering countermeasure to local scour for newly proposed piers. To obtain the optimal geometry, it is necessary to investigate the effect of the horizontal profile and vertical profile on the flow pattern around the piers. In a separate paper, the effect of the cross section was studied, and the optimal cross section was obtained. Continuing the effort, this paper investigates the effect of vertical profile curvatures. To achieve this goal, Bézier curves were used to parameterize the vertical curvatures. Fifty-one three-dimensional computational fluid dynamics models with different curvatures for the pier's vertical profile were constructed by varying the Bézier parameters and computed by COMSOL. All pier models in the flume had the same block ratio to ensure that results from test cases were comparable. Analysis and comparison of the simulation results showed that both a concave (or sloped) nose and a concave sidewall reduced the maximum shear stress around piers and that increasing the concave curvature of the sidewall enhanced the reduction effect. Increasing the concave curvature of the nose, however, tended to diminish the reduction effect. The practical implications from the findings are discussed in this paper.

FACE PROFILE RECOGNITION AND IDENTIFICATION

Since the early 1990's face Recognition Technology (FRT) became anactive research area. Most of the current profile recognition algorithmsdepend on the correct detection of fiducial points and the determination ofrelationships among these fiducial points. Unfortunately, some featuressuch as concave nose, lips, flat chin, etc. make detection of such pointsdifficult and unreliable. Also the number and position of fiducial pointsvary when pose changes even for the same person. In this paper, acurvature-proposed technique is presented, which does not require theextraction of all the fiducial points, but uses information contained in theprofile. The nearest neighbor interpolation method is used to smooth theprofile and then the curvature of the interpolated profile is computed.Using the curvature coefficient values, the fiducial points, such as nasion,chin, and forehead can be reliably extracted using a fast and simplemethod. Then an Euclidean distance method is applied to match the faceprofile based on the curvature coefficient values.Experiments are performed on collected 50 clients with different ages, inpublic area. Each had three shots differences in time capture andilluminations, getting total of 150 images database, recognition rate of96.67% and conclusion are presented and discussed.

Lack of detection of circulating skin-specific IgE autoantibodies in dogs with moderate or severe atopic dermatitis

Human patients with atopic dermatitis (AD) commonly exhibit IgE reactivity to cutaneous self-antigens. The presence of serum IgE autoantibodies appears to correlate with disease severity, and it is suspected to reflect or contribute to tissue damage. The objective of this study was to determine whether IgE autoantibodies specific for cutaneous antigens could be detected in the serum of dogs with AD. Serum was collected from 19 dogs with untreated moderate to severe AD and four specific-pathogen free (SPF) dogs. Indirect immunofluorescence was performed using normal canine skin collected at four different locations (concave ear, nose, medial thigh and lateral thorax), while Western immunoblotting was done using normal canine ear pinna epidermal and dermal extracts and reducing conditions. In both methods, IgE was detected using a monoclonal antibody specific for heat stable epitopes of canine IgE. At 1:10 dilution, specific IgE autoantibodies against cutaneous autoantigens were not detected, with either method, in AD and SPF canine sera. Either IgE autoreactivity is not associated with moderate to severe AD in dogs, or the methods employed herein were not sensitive enough to permit IgE autoantibody detection.

Two brothers with macrocephaly, progressive cerebral atrophy and abnormal white matter, severe mental retardation, and Lennox-Gastaut spectrum type epilepsy: An inherited encephalopathy of childhood?

Two brothers with severe mental retardation of unknown origin were found to share several physical anomalies, including large round head, small concave nose, downslanted palpebral fissures, and gingival hyperplasia. In addition to relative macrocephaly, magnetic resonance imaging (MRI) showed severe cerebral atrophy, especially fronto-temporally. The brothers also had a thin corpus callosum and atrophic caudate nuclei. The reduced white matter showed patchy periventricular signal intensity changes. The lateral and third ventricles were large, but the fourth ventricle was of normal size. The boys had large cisterna magna, communicating widely with the fourth ventricle, but no vermian hypoplasia. Both boys had Lennox-Gastaut spectrum type epilepsy. No chromosomal anomalies were found, despite the suggestive clinical picture. Some of the clinical findings resembled fetal alcohol effects/fetal alcohol syndrome (FAE/FAS), which was also suggested by history. Current diagnostic criteria for FAE/FAS, however, excluded full-blown FAS in these cases and failed to explain the entire clinical picture in the boys. We argue that these boys had an unidentified inherited syndrome, possibly modified by fetal alcohol exposure.

The Negritos: the Distribution of the Negritos in the Philippine Islands and Elsewhere

DR. A. B. MEYER, the distinguished Director of the Royal Zoological, Anthropological and Ethnographical Museum at Dresden, has issued as a separate volume a translation of two chapters, brought up to date, of his sumptuous folio monograph “Die Philippinen: II. Negritos” (1893). The Negritos of the Philippines are a dwarf, 1 frizzly-haired people with a black or dull copper-coloured skin. The head is on the lower limit of brachycephaly (average index about 80). The fore-head is retreating, the concave nose is broad and flat, the projecting jaw is provided with thick lips and prominent teeth. The slender body is almost entirely smooth. They are a happy, lively people to whom care seems a stranger, their greatest anxiety being the procuring of food, which consists of all things edible—fruits, roots, honey, snakes, &c. When they have provided for their wants they care for no further exertion, and love to lie in laziness and ease. Their intelligence is stated to be of a low type, and they are not able to count above five. Their songs consist of monotonous, endless unison chants. Tattooing is apparently universal, the patterns being quite simple. They are without exception monogamists. The Negritos: the Distribution of the Negritos in the Philippine Islands and Elsewhere. By A. B. Meyer. Pp. 92. (Dresden: Stengel and Co.)