Journal articles: 'HEMISPHERICAL TIP'

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DAVIES, KERRIE A., WEIMIN YE, GARY S. TAYLOR, SONJA SCHEFFER, F. BARTHOLOMAEUS, and ROBIN M. GIBLIN-DAVIS. "Nematodes from galls on Myrtaceae. XI. Descriptions of five new species of Fergusobia from Australia." Zootaxa 4399, no. 1 (March 20, 2018): 1. http://dx.doi.org/10.11646/zootaxa.4399.1.1.

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Five new species of Fergusobia are described. Fergusobia janetae Davies n. sp. is characterized by the combination of an arcuate to straight, spindle-shaped parthenogenetic female with a relatively small oesophageal gland, an extensile uterus and a conoid tail, an arcuate infective female with a bluntly rounded tail tip, and a C-shaped male with an arcuate to angular spicule and bursa arising at more than 90% of body length. Fergusobia robustae Davies n. sp. is characterized by the combination of a small, C-shaped parthenogenetic female with a short cylindroid tail with a broadly rounded tip; an arcuate to C-shaped, relatively broad, infective female with a tail tip that is almost hemispherical; and an arcuate male with a strong angular spicule and a bursa arising at 30–40% of body length. Fergusobia pruinosae Davies n. sp. is characterized by the combination of a medium sized, open C-shaped, parthenogenetic female in which the cuticle does not swell upon fixation, with a strongly sclerotised stylet, with a more or less narrowly conoid tail with a bluntly or broadly rounded tip; infective female that is arcuate to J-shaped with a notched tail tip; and open C-shaped males with stout, angular spicules and bursa arising near the secretory/excretory pore. Fergusobia pauciflorae Davies n. sp. is characterized by the combination of a medium sized, arcuate, parthenogenetic female with a small stylet, and a conoid tail with a bluntly rounded tip; a small, open C to J-shaped infective female with a broadly rounded to almost hemispherical tail tip; and straight to arcuate males with stout, angular spicules and bursa at ~70% of body length anterior to the cloaca. Fergusobia obliquae Davies n. sp. has a relatively broad, arcuate, parthenogenetic female having a small but strongly sclerotised stylet, and a short conoid tail with a bluntly rounded tip; an arcuate, infective female with an almost hemispherical tail tip; and C-shaped males with arcuate to angular (not heavily sclerotised) spicules and bursa arising 50–80% of body length anterior to tail. Sequencing of the 18S and 28S rDNA domains for F. janetae n. sp. and of mitochondrial DNA cytochrome oxidase subunit I (mtCOI) for F. pauciflorae n. sp. confirm that they are distinct species.

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Christman, Locke. "Optimization of LaB6 Cathode Tip Shape for Maximum Brightness Over Lifetime." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 430–31. http://dx.doi.org/10.1017/s0424820100180902.

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LaB6 cathodes are widely used as high brightness cathodes in electron microscopy and are capable of providing about five times the brightness of a tungsten hairpin filament. It is desirable to optimize the shape of the LaB6 tip to provide the highest possible brightness and to insure that this high level of brightness is maintained over the life of the cathode.It is well known that a high brightness electron beam is important in obtaining ultimate resolution in electron microscopy. Brightness is defined as the current density per unit solid angle, or amperes per square centimeter per steradian, in the electron beam. In electron microscopy, one would like to obtain the maximum possible brightness for the particular electron gun. Brightness is a conserved quantity, meaning that as the beam traverses the column, brightness can not be gained, only lost. Therefore, one must begin with the brightest possible cathode in order to obtain the best possible electron beam brightness.Much work has been done to determine the optimum LaB6 cathode tip shape and crystallographic orientation which will provide the highest brightness over cathode lifetime. The purpose of this is to review some of the previous results, present further data, and draw conclusions as to the optimum LaB6 cathode tip shape for high sustained brightness over cathode life. Nearly all commercially available LaB6 cathodes for electron microscopy employ an axially oriented LaB6 <100> crystal with a conical tip. Most are made with a full cone angle of 2α=90° (Figure 1). Some have a small radius, hemispherical point at the apex of the cone, while others simply have a small diameter truncation (flat) on top of the cone. The geometrical parameters affecting cathode brightness which will be considered here are hemispherical tip radius (R) and flat diameter (ϕ). Of primary interest is the dependence of brightness over lifetime with the variation of these parameters, and the comparison between the hemispherical and the flat tips.

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Roy, T., and R. Balasubramaniam. "Effect of various factors influencing the generation of hemispherical micro features using non-conformal RMEDM." Journal of Micromanufacturing 2, no. 2 (April 1, 2019): 110–22. http://dx.doi.org/10.1177/2516598419829593.

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Non-conformal reverse micro electrical discharge machining (NC-RMEDM) is a variant of conventional RMEDM developed by the present authors wherein modification in the tool is carried out to generate different shapes of micro features. In this study, the effect of various factors like flat bottom and taper bottom hole, inversing the position of tool and workpiece and changing the hole depth have been experimentally investigated to determine the optimal combination required for generating hemispherical shaped micro features. It was found that hemispherical shaped micro feature can be generated by employing tapered bottom blind hole as tool. Buoyancy assisted machining (BAM) with traverse of workpiece (anode) downwards into the tool (cathode) and vice versa, i.e., buoyancy opposed machining (BOM) with traverse of tool downwards into the workpiece were carried out to study the generation of hemispherical micro feature based on inversion of electrode positions. Although both BAM and BOM generated hemispherical shaped feature, BAM is preferred due to reduced machining time as opposed to BOM. Also, increasing the hole depths led to altering the shape of micro feature from hemispherical to cylindrical with hemispherical end and coni-spherical end. An array of hemispherical micro features was fabricated based on the finding from this study, and surface roughness analysis was carried out which showed that irrespective of the position of micro feature on the array, surface roughness at the tip and base of the micro feature is lower as compared to side portion.

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Yao, Tao, Shu-Dao Zhou, Min Wang, Song Ye, and Yang-Chun Zhang. "Optimal Design of Hemispherical 7-Hole Probe Tip With Perpendicular Holes." IEEE Access 9 (2021): 85101–8. http://dx.doi.org/10.1109/access.2021.3087613.

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Hollis, Brian R. "Correlation of Recent and Historical Hemispherical Nose Tip Distributed Roughness Transition Data." Journal of Spacecraft and Rockets 56, no. 3 (May 2019): 664–86. http://dx.doi.org/10.2514/1.a34219.

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FASOULAS, J., and Z. DOULGERI. "ACTIVE CONTROL OF ROLLING MANOEUVRES OF A ROBOTIC FINGER WITH HEMISPHERICAL TIP." International Journal of Humanoid Robotics 07, no. 01 (March 2010): 183–212. http://dx.doi.org/10.1142/s0219843610002039.

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In this paper we are concerned with the problem of sensory motor coordination of a robotic finger in order to evoke rolling maneuvers in a force-positioning task on a flat rigid surface. We use two different approaches to modeling the reaction of the soft fingertip with the contacted surface. Firstly, we assume that the environment imposes a purely kinematic rolling constraint on the end-effector motion in the tangent direction of the contacted surface. This implies no energy transfer or dissipation between the fingertip and the environment due to frictional forces. On the other hand, we assume that it is feasible for the fingertip to slip in which case pure rolling motion could be disturbed. The two different models are subsequently used to show by simulation that control laws, which have been designed on a rolling constraint dynamic model for frictional forces, fail to perform rolling in various environments. An extra control input that uses a reference rolling trajectory that is state dependent is proposed, which, if superimposed on a conventional force-position control law, can achieve rolling even on a surface with low friction characteristics. The proposed feedback signal does not utilize the modeling information in the control formulation, and thus permits easy implementation. Finally, the total controller is shown to achieve asymptotic convergence to the desired force-positioning task by simultaneously evoking pure rolling motion for the fingertip.

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Wibowo, Edy, Sutisna, Naily Ulya, and Mamat Rokhmat. "Spin Direction of a Hemispherical Object." Physics Teacher 61, no. 3 (March 2023): 222–23. http://dx.doi.org/10.1119/5.0048889.

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When rotating a ball using a hand [Figs. 1(a) and (b)], the fingers that touch the ball’s outer surface will exert frictional forces on the ball. These frictional forces cause torques on the ball so that the ball spins in the same direction as the finger’s rotational direction. If the finger rotates clockwise, the ball’s rotational direction will also be clockwise and vice versa. When the ball is cut into half, it is rotated similarly to when spinning a full ball. Thus, we can easily guess that its direction of rotation will be the same as when circling a full ball. What if the ball is spun differently? The half ball is spun using one fingertip from the bottom center of the inside, as shown in Figs. 1(c) and (d). What is the direction of rotation of the half ball? Would it be the same as when the ball is rotated from the outside? It turns out that the spin direction of the half ball is the opposite of the finger’s spin direction. The same result was observed when using a pen or a stick to rotate the half ball from the center base [Fig. 1(d) and supplemental video. Finally, suppose we shift the finger’s tip to any location so that it will no longer be at the center of the bottom of the object. In that case, the half ball’s rotation direction is similar to the one of the finger or stick. Why does this happen? In this paper, the answer to this question is presented.

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Ahmida, Mahmoud Abdelrazek, Mahmoud Abdelrazek Ahmida, Abdlmanam S. A. Elmaryami, Farag Gait Abelrahman Boukhrias, and Ahmed M. Ahmed El Menshaz. "Investigation of Using Physical Optical Reflectivity Probes in Evaluating and Monitoring Powder Mixtures of Sugar and Slag." Instrumentation Mesure Métrologie 21, no. 2 (April 30, 2022): 43–48. http://dx.doi.org/10.18280/i2m.210202.

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A preliminary investigation of some factors which can affect the reflected light intensity from granular and icing sugar has been carried out using an end viewing hemispherical tip probe. It is found that the reflectance is strongly dependent on the size range of the sugar particles, with the finer particles being more reflective. This property could be very useful in monitoring segregation in mixtures of mono-colored powders having different size distributions. Force applied to the probe will also affect the intensity readings. A layered mixture of sugar and slag powder was used to compare the sampling performance of the above probe with a side viewing wedge tip probe. Calibration curves for reflected light intensity versus percent slag concentration are obtained for two types of slag.

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DAVIES, KERRIE, ROBIN GIBLIN-DAVIS, WEIMIN YE, GARY TAYLOR, and KELLEY THOMAS. "Nematodes from galls on Myrtaceae. III. Fergusobia from flower bud and stigma galls on Eucalyptus, with descriptions of four new species." Zootaxa 3532, no. 1 (October 31, 2012): 1. http://dx.doi.org/10.11646/zootaxa.3532.1.1.

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Four new species of Fergusobia from flower bud galls and a stigma gall on Eucalyptus spp. in Australia are described. Fer-gusobia eugenioidae Davies n. sp. is characterised by having an arcuate, open C or C-shaped parthenogenetic female witha conoid tail, an arcuate to open C-shaped infective female with a hooked tail region and a broadly rounded tail tip, andarcuate or open C-shaped males with angular spicules and short bursa. Fergusobia fasciculosae Davies n. sp. is character-ised by the combination of an arcuate parthenogenetic female with a short, broadly conoid tail, an open C-shaped infectivefemale with a hemispherical tail tip, and J-shaped males with angular spicules and short peloderan bursa. This is the firstFergusobia/Fergusonina association to be described from flower stigma galls. Fergusobia juliae Davies n. sp. is character-ised by the combination of an arcuate to C-shaped parthenogenetic female with a short, broadly conoid tail, a J-shaped in-fective female with a hooked tail region, a cuticular plate around the vulva, and a broadly rounded tail tip, and J-shapedmales with angular spicules and short peloderan bursa. Fergusobia morrisae Davies n. sp. has a C-shaped parthenogeneticfemale with a narrowly conoid tail, an arcuate or J-shaped infective female with most curvature behind the vulva and a shorttail with an almost hemispherical tip, and arcuate or J-shaped males with strongly sclerotised, angular spicules and a longpeloderan bursa. Other known similar forms of Fergusobia/Fergusonina flower bud galls from Eucalyptus spp. are outlinedand the larval shield morphology of their associated mutualistic fly species is discussed where known. An inventory of allknown Fergusobia/Fergusonina associations from flower bud galls from Eucalyptus spp. is presented. Molecular analysisof Fergusobia nematodes was inferred from DNA sequencing of 28S rDNA D2/D3 domains and a portion of mitochondrial DNA cytochrome oxidase subunit I (mtCOI). Possible evolutionary relationships are discussed.

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Tembhurnikar, Payal, Akash Jadhav, and Devabrata Sahoo. "Effect of intermediate aerodisk mounted sharp tip spike on the drag reduction over a hemispherical body at Mach 2.0." FME Transactions 48, no. 4 (2020): 779–86. http://dx.doi.org/10.5937/fme2004779t.

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Reduction of forebody drag in high speed flying vehicles such as rockets and missiles are of high research interest in the present time. In the present research, drag reduction obtained by using an intermediate aerodisk mounted sharp tip spike has been investigated using computational studies at Mach number of 2.0. The flowfield over a hemispherical blunt body with an intermediate aerodisk mounted sharp tip spike is investigated at zero degree angle of attack and the amount of drag reduction obtained is then compared with that of a conventional sharp tip spike mounted hemisphere. The presence of an intermediate aerodisk changes the flow physics and shock system over the blunt body. The change in the system of shock waves by mounting an intermediate aerodisk results in a higher percentage (20% higher) of drag reduction generated by the blunt spiked body moving at a supersonic speed of Mach 2.0. Use of intermediate aerodisk proves to be beneficial in terms of drag reduction for spike lengths ranging beyond the critical length.

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Pang, S. S., and A. A. Kailasam. "A Study of Impact Response of Composite Pipe." Journal of Energy Resources Technology 113, no. 3 (September 1, 1991): 182–88. http://dx.doi.org/10.1115/1.2905802.

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The objective of this study was to gain a better understanding of the low-velocity impact phenomena of composite pipe. The focus was on test method development, and material and damage characterization. A drop weight tower tester was designed in this investigation. The dynamic tests were conducted using three different impactor geometries, velocities, and masses. It was found that the damage was localized and on the outer surface of the pipe in the case of the conical and wedge tip impactors. On the other hand, the damage zone was larger than the impact zone for the hemispherical impactor, and cracks were first seen within the inner surface of the pipe. This implies that the hemispherical tip impactor caused more damage to the pipe than the conical or wedge tips. The energy absorbed slightly increased with an increase in velocity or in mass. The contact period for the conical impactor was the longest. The velocity and mass of the impactor had only a slight effect on that period. The wedge impactor generated the largest peak force. The energy absorbed by the two composite pipes under low-velocity impact was studied. The specimen-1, Derakane 411-45 resin with less glass fiber, seemed to absorb more energy compared to the specimen-2, Derakane 470-36 resin with more glass fiber. In addition, the specimen-2 exhibited a slightly higher maximum impact force. Therefore, impact response is sensitive to fiber content.

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Manavi, Tejaswini, Masooma Ijaz, Sajjad Soleimani, Junaid Zafar, Faisal Sharif, and Haroon Zafar. "Experimental Analysis of Transseptal Puncture to Investigate the Mechanical Properties of Fossa Ovalis." Applied Sciences 13, no. 2 (January 13, 2023): 1065. http://dx.doi.org/10.3390/app13021065.

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Background/Objective: Optimization of needle characteristics for trans-septal puncture is of paramount importance to reduce the extent of tissue deformation. This was achieved by studying the mechanical behavior of fossa ovalis (FO) in lamb hearts. The fossa ovalis tissue samples obtained after dissection were subjected to experimental indentation and tensile tests to determine tissue deformation. Methods: Lamb hearts (n = 20) were dissected to obtain fossa ovalis tissue samples. These were subjected to indentation and tensile tests to determine the puncture and rupture forces respectively. Indentation tests were performed using two different indenters: A steel indenter with a hemispherical tip and a Brockenbrough (BRK) needle (bevel tip). Tensile tests were formed using Zwick Roell (Z005) tensile machine at 100 N load cell. ImageJ analysis was also performed to determine the diameter and shape of FO. Results: Indentation results demonstrated that the hemispherical indenter requires a greater punch force compared to the puncture force with the BRK needle. The mean punch force of the hemispherical indenter (15.57 N) was nearly 3 times greater than the puncture force of the BRK needle (5.47 N). Variations between the two indenters provide an insight into the importance of device geometry on trans-septal procedures. The tensile test results illustrated a typical failure pattern with a toe region, linear region, and failure region. The mean rupture force determined was 10.51 N. ImageJ analysis confirmed an oval shape of FO and the diameters measured were in the range 9.0–15.3 mm. Conclusions: The mechanical aspects of fossa ovalis in lamb hearts were successfully studied through a series of experimental indentation and tensile tests. This study serves as a guide to dissecting the challenging FO sample. The procedures for indentation and tensile tests are detailed with common experimental challenges encountered addressed. The correlation of the parameters involved in these experimental tests to the collagen fiber orientation in tissues is also discussed, providing an insight into the deformation of tissues and variations in fiber orientation before and after trans-septal procedures.

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Wang, Xu, Yiwu Fang, Munawar Maria, Jianfeng Gu, and Jianjun Ge. "Description of Bursaphelenchus rockyi n. sp. (Nematoda: Aphelenchoididae) in peat moss from Russia." Nematology 21, no. 3 (2019): 253–65. http://dx.doi.org/10.1163/15685411-00003211.

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Summary Bursaphelenchus rockyi n. sp., isolated in Peking, China, from peat moss imported from Russia, is described. It is characterised by a lateral field with four lines, excretory pore located at the base of the nerve ring or slightly posterior, spicule 15.9 (15.1-17.3) μm long along the chord and with high condylus and a rounded tip, rostrum triangular or conical with bluntly pointed tip, lamina curvature becoming more pronounced at 60% of total length, six caudal papillae with P3 and P4 adjacent to each other, bursa small, starting posterior to P4, vulval lips hemispherical and protruding, and tail conical with finely rounded or mucronated terminus. The new species belongs to the fungivorus-group and is most similar to B. arthuri, B. arthuroides, B. fungivorus and B. seani, but can be distinguished from related species by morphological and sequencing results.

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MIZUTANI, Katsumi, Kai EGASHIRA, Kazuo MURATA, and Masanori ITOH. "Fabrication of Hemispherical Tool Tip of Ultra Small Diameter via Electrode Wear Phenomenon in EDM." Denki Kako Gakkaishi 40, no. 93 (2006): 36–41. http://dx.doi.org/10.2526/jseme.40.36.

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Koelling, S., N. Innocenti, A. Schulze, M. Gilbert, A. K. Kambham, and W. Vandervorst. "In-situ observation of non-hemispherical tip shape formation during laser-assisted atom probe tomography." Journal of Applied Physics 109, no. 10 (May 15, 2011): 104909. http://dx.doi.org/10.1063/1.3592339.

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Yuvaraj, S., R. Malayalamurthi, S. Gokulprasath, and K. Venkatesh Raja. "Assessment of contact parameters of soft splined hemispherical finger-tip pressed against a concave profile." Materials Research Express 5, no. 6 (June 26, 2018): 065319. http://dx.doi.org/10.1088/2053-1591/aac259.

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Xie, Gongnan, and Bengt Sundén. "Numerical predictions of augmented heat transfer of an internal blade tip-wall by hemispherical dimples." International Journal of Heat and Mass Transfer 53, no. 25-26 (December 2010): 5639–50. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2010.08.019.

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Yuvaraj, S., R. Malayalamurthi, and K. Venkatesh Raja. "Assessment of the contact behavior of a soft hemispherical finger tip in curved profile grasping." International Journal of Materials Research 107, no. 9 (September 15, 2016): 777–82. http://dx.doi.org/10.3139/146.111410.

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Takino, Hideo, Kazuya Yamamura, Yasuhisa Sano, and Yuzo Mori. "Shape correction of optical surfaces using plasma chemical vaporization machining with a hemispherical tip electrode." Applied Optics 51, no. 3 (January 20, 2012): 401. http://dx.doi.org/10.1364/ao.51.000401.

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DOONAN, J. H., D. J. COVE, and C. W. LLOYD. "Microtubules and microfilaments in tip growth: evidence that microtubules impose polarity on protonemal growth in Physcomitrella patens." Journal of Cell Science 89, no. 4 (April 1, 1988): 533–40. http://dx.doi.org/10.1242/jcs.89.4.533.

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In this study we compare the contributions of Factin and microtubules to tip growth in filamentous cells of the moss Physcomitrella patens. In tip growth, expansion seems to be restricted to the hemispherical apical dome. Cytoskeletal elements have been suspected, from drug studies, to be involved in this but electron microscopy has generally not confirmed the presence of an apical cytoskeleton. However, in a previous immunofluorescence study we reported that microtubules could be seen to focus upon the apical dome in tip cells of the moss P. patens. In the present investigation F-actin has also been detected at the apices of these cells. Anti-cytoskeletal drugs were therefore used to differentiate between the roles of actin filaments and microtubules in tip growth. At high concentrations (30μM), the herbicide cremart de-polymerized microtubules and caused tip swelling. F-actin was still present under such conditions but its fragmentation by cytochalasin D suppressed this herbicide-induced swelling. On its own, cytochalasin D arrested tip growth without causing swollen tips. At lower concentrations, cremart disorganized microtubules rather than causing their complete depolymerization. Under these conditions, new but swollen growing points were initiated along the filament. The addition of taxol to cremart-treated filaments tended to reduce swelling and to re-polarize outgrowth. With particular combinations of these drugs, multiple lateral out-growths were initiated in the vicinity of the nucleus. It is concluded: (1) that F-actin is present at the tips of Physcomitrella caulonemal apical cells; (2) that unfragmented F-actin is necessary for outgrowth; (3) that even disorganized microtubules permit some degree of outgrowth but that an unperturbed distribution of axial microtubules, focussing upon an apex, is essential in order to impose tubular shape and directionality upon expansion.

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Qu, Jian, Yi Liu, Yan Li, Jinjian Li, and Songhe Meng. "Microfluidic Chip with Fiber-Tip Sensors for Synchronously Monitoring Concentration and Temperature of Glucose Solutions." Sensors 23, no. 5 (February 23, 2023): 2478. http://dx.doi.org/10.3390/s23052478.

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Monitoring the properties of fluids in microfluidic chips often requires complex open-space optics technology and expensive equipment. In this work, we introduce dual-parameter optical sensors with fiber tips into the microfluidic chip. Multiple sensors were distributed in each channel of the chip, which enabled the real-time monitoring of the concentration and temperature of the microfluidics. The temperature sensitivity and glucose concentration sensitivity could reach 314 pm/°C and −0.678 dB/(g/L), respectively. The hemispherical probe hardly affected the microfluidic flow field. The integrated technology combined the optical fiber sensor with the microfluidic chip and was low cost with high performance. Therefore, we believe that the proposed microfluidic chip integrated with the optical sensor is beneficial for drug discovery, pathological research and material science investigation. The integrated technology has great application potential for micro total analysis systems (μ-TAS).

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Rolland, Nicolas, François Vurpillot, Sébastien Duguay, Baishakhi Mazumder, James S. Speck, and Didier Blavette. "New Atom Probe Tomography Reconstruction Algorithm for Multilayered Samples: Beyond the Hemispherical Constraint." Microscopy and Microanalysis 23, no. 2 (March 22, 2017): 247–54. http://dx.doi.org/10.1017/s1431927617000253.

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AbstractAccuracy of atom probe tomography measurements is strongly degraded by the presence of phases that have different evaporation fields. In particular, when there are perpendicular interfaces to the tip axis in the specimen, layers thicknesses are systematically biased and the resolution is degraded near the interfaces. Based on an analytical model of field evaporated emitter end-form, a new algorithm dedicated to the 3D reconstruction of multilayered samples was developed. Simulations of field evaporation of bilayer were performed to evaluate the effectiveness of the new algorithm. Compared to the standard state-of-the-art reconstruction methods, the present approach provides much more accurate analyzed volume, and the resolution is clearly improved near the interface. The ability of the algorithm to handle experimental data was also demonstrated. It is shown that the standard algorithm applied to the same data can commit an error on the layers thicknesses up to a factor 2. This new method is not constrained by the classical hemispherical specimen shape assumption.

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Kennefick, C. M. "Constrained Cavitation and Fast Fracture at Metal-ceramic Interfaces at Elevated Temperatures." Journal of Materials Research 14, no. 4 (April 1999): 1306–15. http://dx.doi.org/10.1557/jmr.1999.0178.

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Processes that constrain or promote cavity growth and fast fracture at elevated temperatures are examined. Solutions are given for the stress caused by inhomogeneous deposition of matter in metal-ceramic and alumina grain boundaries and for the tensile stress near the top of a hemispherical pore during pore growth. Velocities of dislocation climb that could promote fast fracture are calculated for elastic stresses acting upon dislocations arising from both a crack tip and interface repulsion. The rates for the atomic diffusive processes and the magnitudes of stresses resulting from them are found to agree well with experimental rate of pore growth, and new data on pore growth and fracture at an aluminum-sapphire interface are presented.

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Azwan, Syed Mohd Saiful, Yahya Mohd Yazid, Ayob Amran, and Behzad Abdi. "Quasi-Static Indentation Behaviour of Glass Fibre Reinforced Polymer." Advanced Materials Research 970 (June 2014): 317–19. http://dx.doi.org/10.4028/www.scientific.net/amr.970.317.

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Fibre reinforced polymer (FRP) plates subject to quasi-static indentation loading were studied. The plates were fabricated from three layers of chopped strand mat glass fibre and polyester resin using vacuum infusion process. Indentation tests were conducted on the plates with loading rates of 1 mm/min, 10 mm/min, 100 mm/min and 500 mm/min using a hemispherical tip indenter with diameter 12.5 mm. The plates were clamped in a square fixture with an unsupported space of 100 mm × 100 mm. The loads and deflections at the indented location were measured to give energy absorption-deflection curves. The results showed that the loading rate has a large effect on the indentation behaviour and energy absorbed.

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Novak, A. V., V. R. Novak, and A. V. Rumyantsev. "Features of the Manufacturing Process of Silicon Tips for Cantilevers." Proceedings of Universities. Electronics 26, no. 3-4 (2021): 234–45. http://dx.doi.org/10.24151/1561-5405-2021-26-3-4-234-245.

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Sample surface examination in atomic force microscopy is carried out using cantilevers having the form of elastic consoles with sharp needle (tip) at the free end. Quality of images obtained from atomic force microscope (AFM) heavily depends on tip sharpness degree. Silicon cantilevers made based on wet anisotropic etching are widely used in atomic force microscopy. This paper studies the dependence of the shape and size of the resulting tip on the concentration of KOH in the solution, as well as the effect of pyrogenic oxidation and oxidation in a dry oxygen atmosphere on the sharpness of the tip during the sharpening process. It was shown that when 70 % concentration is used, tips with the highest aspect ratio and maximum height are obtained. In this case, the shape of the needle is an octagonal pyramid, the lateral faces of which are formed by eight crystallographic planes from {311} and {131}. It was found that in a two-stage sharpening process, consisting of pyrogenic oxidation and oxidation in a dry oxygen atmosphere, it is possible to form sufficiently sharp probes with a tip radius of 2–5 nm and an apex angle of 14–24°. It has been established that a one-stage sharpening process based on pyrogenic oxidation provides only the production of probes with a radius of about 14 nm. Comparative tests of the manufactured probes in obtaining AFM images of a test sample of a polycrystalline silicon film with hemispherical grains (HSG-Si) were presented. Research study has revealed that such a statistical parameter as the relative increment of the surface area Sdr is the most sensitive to probe sharpness for surfaces of the HSG-Si film type.

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Harada, Takeshi, and Takuya Semba. "A Truing Technique of Flattening Diamond Grains for Fabricating Microstructures with Fine Surfaces." Key Engineering Materials 389-390 (September 2008): 350–55. http://dx.doi.org/10.4028/www.scientific.net/kem.389-390.350.

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A truing technique that can be used to shape the tip of an electroformed diamond tool into a hemisphere and flatten diamond grains on the tool working surface at the same level as the bond face was developed. A polycrystalline diamond disk whose top surface roughened by electrical discharge machining was partially flattened by grinding was used as a truer. Diamond grains on the tool working surface were successfully flattened along the hemispherical tool profile when the grains mesh size of #1000 was employed. In addition, a grinding test using glasslike carbon as a work material revealed that a surface roughness of less than 50 nm Rz could be obtained in both cases when moving the tool on contour and scanning paths.

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Ismail, Mohd Fadzli, Aidah Jumahat, Nurulnatisya Ahmad, and Muhammad Hussain Ismail. "Low Velocity Impact of Aluminium Foam - Glass Fibre Reinforced Plastic Sandwich Panels." Advanced Materials Research 1113 (July 2015): 74–79. http://dx.doi.org/10.4028/www.scientific.net/amr.1113.74.

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Sandwich structures with metal foams core are widely used in various engineering applications due to their special properties of high-strength and high-stiffness to weight ratio when compared to the properties of pure material systems. Sandwich structures have the capability to resist impact loads which make them favorable for energy absorber application. The aim of this research is to investigate the impact properties of aluminium foam sandwiched with glass fibre reinforced plastic (GFRP). Drop weight impact test was conducted using hemispherical impactor tip at velocity of 6.7 m/s by striking the samples with and without face-sheets. The result showed that the GFRP and aluminium foam core sandwich panel exhibited promising energy absorption properties, corresponding to the highest specific energy absorption value observed.

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Mehta, R. C. "Numerical simulation of the flow field over conical, disc and flat spiked body at Mach 6." Aeronautical Journal 114, no. 1154 (April 2010): 225–36. http://dx.doi.org/10.1017/s0001924000003675.

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Abstract A forward facing spike attached to a hemispherical body significantly changes its flow field and influences aerodynamic drag and wall heat flux in a high speed flow. The dynamic pressure in the recirculation area is highly reduced and this leads to the decrease in the aerodynamic drag and heat load on the surface. Consequently, the geometry, that is, the length and shape of the spike, has to be simulated in order to obtain a large conical recirculation region in front of the blunt body to get beneficial drag reduction. It is, therefore, a potential candidate for aerodynamic drag reduction for a future high speed vehicle. Axisymmetric compressible laminar Navier-Stokes equations are solved using a finite volume discretisation in conjunction with a multistage Runge-Kutta time stepping scheme. The effect of the spike length and shape, and the spike nose configuration on the reduction of drag is numerically evaluated at Mach 6 at a zero angle-of-attack. The computed density contours agree well with the schlieren images. Additional modification to the tip of the spike to get different types of flow field such as the formation of a shock wave, separation area and reattachment point are examined. The spike geometries include the conical spike, the flat-disk spike and the hemispherical disk spike of different length to diameter ratios attached to the blunt body.

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29

Lavella, Mario, Daniele Botto, and Muzio M. Gola. "Fretting Damage of Contact Interfaces of CMSX 4 with and without T800 Coating." Key Engineering Materials 417-418 (October 2009): 553–56. http://dx.doi.org/10.4028/www.scientific.net/kem.417-418.553.

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Fretting fatigue is a complex phenomenon that occurs at component interfaces undergoing low amplitude oscillation and high contact pressure. In turbomachinery fretting occurs also at the blade tip interfaces where shrouds are machined with the aim to reduce the blade resonant vibration amplitude. The aim of this study is to investigate the damage by fretting on CMSX4 superalloy interfaces with and without plasma sprayed T800 coating. The contact pair is a hemispherical surface on a flat surface. The hysteresis cycles, namely the contact force against the relative displacement, have been measured through the experiment. The worn surfaces have been characterized by three-dimensional optical interferometry and SEM analysis. After 3×106 and 10×106 fretting cycles the surface without coating shows surface cracks and large change in the contact parameters.

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30

Castillo, Pablo, Ebrahim Pourjam, Juan E. Palomares-Rius, Mohammad Reza Atighi, Carolina Cantalapiedra-Navarrete, and Majid Pedram. "Molecular and morphological characterisations of two new species of Rotylenchus (Nematoda: Hoplolaimidae) from Iran." Nematology 13, no. 8 (2011): 951–64. http://dx.doi.org/10.1163/138855411x571795.

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AbstractTwo new amphimictic species, Rotylenchus iranicus n. sp. and R. conicaudatus n. sp., are described. Rotylenchus iranicus n. sp. is characterised mainly by an offset hemispherical lip region with 5-6, rarely 7, annuli, stylet 39-44 μm long, vulva located at 53-65% and rounded tail with 4-9 annuli and typical smooth tip. Morphologically this species is related to R. montanus, R. provincialis and R. aqualamus. Rotylenchus conicaudatus n. sp. is characterised mainly by a slightly offset conoid-rounded lip region with four or five, rarely six annuli, stylet 27-32 μm long, vulva located at 52-63% and conoid-rounded tail with 10-16 annuli and a typical annulated tip. Morphologically this species is related to R. pumilus, R. abnormecaudatus, R. acuspicaudatus and R. provincialis. The results of the phylogenetic analysis based on sequences of the D2-D3 expansion regions of 28S and ITS1-rRNA genes confirmed the species differentiation. Phylogenetic relationships with other species were difficult to assign using D2-D3 expansion regions of 28S. However, using ITS1-rRNA, R. conicaudatus n. sp. presented a close relationship with R. unisexus, whilst R. iranicus n. sp. was closely related to R. conicaudatus n. sp., R. unisexus, R. incultus and R. laurentinus.

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31

Zhang, Ke, Ju Ping Ren, Guo Zhi Liu, Yu Lan Tang, and Yu Hou Wu. "Simulation of Nano-Indentation of Nano SiC Ceramic Micro-Component." Materials Science Forum 675-677 (February 2011): 263–66. http://dx.doi.org/10.4028/www.scientific.net/msf.675-677.263.

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A 3D model of molecular dynamics for nanoceramic SiC is adopted to simulate the hot pressing sintering and preparation process of SiC, and mechanical properties such as density, hardness and elastic modulus are calculated. Finite element model of indentation is established based on the mechanical performance parameters from MD simulation. Conical indenter is adopted in indentation simulation. The FEM simulation results show that: Maximum equivalent stress appears at the place of indenter tip, and equivalent stress curves are appeared hemispherical. As indentation depth increases, the stress increased. As the distance of away from the indenter increases, the displacement in equivalent displacement nephogram gradually decreased until zero. During unloading process, elastic restitution is occurred. The elastic restitution in the area of below the indenter is obviously. Residual stress in the center of indentation is maximal after unloading.

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32

Sego, David C., and Norbert R. Morgenstern. "Punch indentation of polycrystalline ice." Canadian Geotechnical Journal 22, no. 2 (May 1, 1985): 226–33. http://dx.doi.org/10.1139/t85-030.

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The flow law of polycrystalline ice is extended to a general state of stress and the second stress invariant accounts for the stress dependence. Experimental evidence supports this generalized flow law. Punch indentation experimental results are analyzed using this generalized flow law and the expansion of a hemispherical cavity at the punch tip. A finite element analysis of the punch experiments supports the use of a cavity expansion zone beneath the punch.Analytical, as well as experimental, evidence of a lack of influence of depth of penetration on the punch resistances is presented. This evidence conflicts with data presented by S. S. Vyalov and co-workers in 1973 and reasons for the conflict are presented. These findings suggest that higher bearing capacity factors are applicable at the ice surface. Key words: ice, creep, flow law, punch penetration, multiaxial stress states.

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33

Patra, P., S. Gangopadhyay, and K. Goswami. "Mismatch considerations in laser diode to monomode fiber excitation via a hemispherical lens on the elliptical core fiber tip." Optik 119, no. 12 (September 2008): 596–600. http://dx.doi.org/10.1016/j.ijleo.2007.04.002.

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34

Lindner, Alberto, and Alvaro E. Migotto. "The life cycle of Clytia linearis and Clytia noliformis: metagenic campanulariids (Cnidaria: Hydrozoa) with contrasting polyp and medusa stages." Journal of the Marine Biological Association of the United Kingdom 82, no. 4 (August 2002): 541–53. http://dx.doi.org/10.1017/s0025315402005866.

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The life cycles of Clytia linearis and Clytia noliformis, two common campanulariids previously known solely from their polyp and young medusa stages, were investigated. Adult medusae of C. linearis have a bell diameter of 2·5–3·6 mm, and up to 29 tentacles. The bell is almost flat when relaxed and C-type microbasic mastigophore nematocysts form a cluster at the tip of the tentacles. Mature medusae of C. noliformis have a more hemispherical, saucer-shaped bell (3·5–4·5 mm in diameter), up to 16 tentacles, and no diagnostic nematocysts. Polyps of both species also differ in morphology, colour, and cnidome, and a possible resting structure is described for C. linearis. The relevance of characters from the perisarc and hydranths for taxonomy within the Campanulariidae is also evaluated, and whether the size of nematocysts is variable or not, and therefore appropriate for species identification.

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35

Toivola, Yvete, Andreas Stein, and Robert F. Cook. "Depth-sensing indentation response of ordered silica foam." Journal of Materials Research 19, no. 1 (January 2004): 260–71. http://dx.doi.org/10.1557/jmr.2004.19.1.260.

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Depth-sensing indentation was applied to three-dimensionally ordered silica foams of two different pore diameters—500 nm and 850 nm—formed by colloidal crystal templating. The contact responses of indentations with Berkovich and hemispherical indentation tips are presented over a load range of 1 mN to 100 mN. Scanning electron microscopy images of residual indentation impressions showed homogeneous deformation for small loads in which the peak displacement was shallow relative to the film–substrate interface. The characteristics of the load–displacement responses changed from periodic discontinuities, associated with cell wall fracture and pore collapse, to smooth and increased stiffness, as a result of densification due to the accumulation of material under the indentation tip and proximity (and contact) of the substrate. Load–displacement responses were translated into pressure–volume space, in which the average pressure during indentation is a measure of the crushing pressure of the cell walls.

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36

Perry, Scott S., Joel W. Ager, and Gabor A. Somorjai. "Combined surface characterization and tribological (friction and wear) studies of CVD diamond films." Journal of Materials Research 8, no. 10 (October 1993): 2577–86. http://dx.doi.org/10.1557/jmr.1993.2577.

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The tribological properties of polycrystalline chemically vapor deposited (CVD) diamond films grown on silicon substrates and containing varying amounts of amorphous carbon impurities were investigated. Films were characterized by secondary electron microscopy (SEM) and atomic force microscopy (AFM) for surface morphology and roughness and by spatially resolved Raman spectroscopy for amorphous carbon (a-C) content. Friction measurements were performed with a Rockwell C hemispherical diamond tip in ultrahigh vacuum (UHV) and in ambient air. In vacuum, the friction coefficient rises monotonically from 0.6 in a region with substantial a-C to 0.85 in a region with pure diamond. Under ambient conditions, the friction coefficient is substantially lower than that in vacuum and deceases slightly (from ∼0.19 to ∼0.16) with the decreasing a-C content. Under both vacuum and ambient conditions, the friction coefficient was observed to be independent of load over the range of 0.1–0.5 N. The friction values are discussed in terms of adhesion between the diamond tip and the film. Qualitative scratch hardness measurements were performed in UHV by measuring the minimum load at which plastic deformation occurs for a single traversal of the tip. Scratch hardness is found to increase with increasing diamond content of the films. The wear mechanism of the pure diamond regions was evaluated by examining wear tracks with SEM and AFM. The wear tracks showed evidence of spalling, buckling, and grain pull-out indicative of a cohesive mode of failure (failure at grain boundaries). A decrease in surface roughness in the wear tracks indicates asperity wear. Adhesive failure at the Si substrate interface or of a phase transformation of the diamond film was not observed in this load regime.

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37

MARSTON, J. O., I. U. VAKARELSKI, and S. T. THORODDSEN. "Bubble entrapment during sphere impact onto quiescent liquid surfaces." Journal of Fluid Mechanics 680 (June 20, 2011): 660–70. http://dx.doi.org/10.1017/jfm.2011.202.

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We report observations of air bubble entrapment when a solid sphere impacts a quiescent liquid surface. Using high-speed imaging, we show that a small amount of air is entrapped at the bottom tip of the impacting sphere. This phenomenon is examined across a broad range of impact Reynolds numbers, 0.2 ≤ Re = (DU0/νl) ≤ 1.2 × 105. Initially, a thin air pocket is formed due to the lubrication pressure in the air layer between the sphere and the liquid surface. As the liquid surface deforms, the liquid contacts the sphere at a finite radius, producing a thin sheet of air which usually contracts to a nearly hemispherical bubble at the bottom tip of the sphere depending on the impact parameters and liquid properties. When a bubble is formed, the final bubble size increases slightly with the sphere diameter, decreases with impact speed but appears independent of liquid viscosity. In contrast, for the largest viscosities tested herein, the entrapped air remains in the form of a sheet, which subsequently deforms upon close approach to the base of the tank. The initial contact diameter is found to conform to scalings based on the gas Reynolds number whilst the initial thickness of the air pocket or ‘dimple’ scales with a Stokes' number incorporating the influence of the air viscosity, sphere diameter and impact speed and liquid density.

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38

Gohya, Naoko, Wan Fu Sun, Yoshifumi Amamoto, and Takuya Semba. "Electroformed Diamond Tool Adaptable to Nanometer Grinding of Cemented Carbide." Key Engineering Materials 516 (June 2012): 1–6. http://dx.doi.org/10.4028/www.scientific.net/kem.516.1.

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An electroformed diamond tool with a tool tip radius of 0.2 mm was developed to achieve a surface roughness of less than 10 nm Rz on a mould made of cemented carbide. A polycrystalline diamond disc with a primary grain size of 0.5 µm and a diameter of 15 mm was used as a truer. A concentric guide groove with a reverse profile relative to the hemispherical tool and a surface roughness of 0.5 µm Rz was preformed on the truer by laser machining and wet lapping. It was verified through a truing test that 93 % of the diamond grains on the tool working surface could be flattened when the tool was placed in elastic contact with a guide groove with a depth of 50 µm. A grinding test revealed that the tool had the potential to efficiently fabricate a ground surface with a roughness of less than 10 nm Rz on cemented carbide with a hardness of 2600 Hv.

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39

Disna Jayampathi Karunanayake, K. P., Bin Xu, and Yasushi Hoshino. "Electrostatic force acting on conductive ball between electrodes II: Cylindrical upper electrode with hemispherical tip for capturing/releasing conductive ball." Journal of Electrostatics 69, no. 6 (December 2011): 596–600. http://dx.doi.org/10.1016/j.elstat.2011.08.002.

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40

Kalimuthu, R., R. C. Mehta, and E. Rathakrishnan. "Investigation of aerodynamic coefficients at Mach 6 over conical, hemispherical and flat-face spiked body." Aeronautical Journal 121, no. 1245 (October 2, 2017): 1711–32. http://dx.doi.org/10.1017/aer.2017.100.

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ABSTRACTA forward spike attached to a blunt body significantly alters its flow field characteristics and influences aerodynamic characteristics at hypersonic flow due to formation of separated flow and re-circulation region around the spiked body. An experimental investigation was performed to measure aerodynamic forces for spikes blunt bodies with a conical, hemispherical and flat-face spike at Mach 6 and at an angle-of-attack range from 0° to 8° and length-to-diameterL/Dratio of spike varies from 0.5 to 2.0, whereLis the length of the spike andDis diameter of blunt body. The shape of the leading edge of the spiked blunt body reveals different types of flow field features in the formation of a shock wave, shear layer, flow separation, re-circulation region and re-attachment shock. They are analysed with the help of schlieren pictures. The shock distance ahead of the hemisphere and the flat-face spike is compared with the analytical solution and is showing satisfactory agreement with the schlieren pictures. The influence of geometrical parameters of the spike, the shape of the spike tip and angle-of-attack on the aerodynamic coefficients are investigated by measuring aerodynamic forces in a hypersonic wind tunnel. It is found that a maximum reduction of drag of about 77% was found for hemisphere spike ofL/D= 2.0 at zero angle-of-attack. Consideration for compensation of increased pitching moment is required to stabilise the aerodynamic forces.

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41

Kang, Myungsung, Joo-Hee Kang, Hyeonuk Park, Jun-Hyung Kim, Young-Sik Pyoun, Minjae Baek, Dong Jun Lee, et al. "Through-Thickness Microstructures and Yield Strength Enhancement for AZ31 Mg Sheets Treated by Ultrasonic Nanocrystal Surface Modification." Korean Journal of Metals and Materials 60, no. 3 (March 5, 2022): 169–79. http://dx.doi.org/10.3365/kjmm.2022.60.3.169.

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An ultrasonic nanocrystal surface modification (UNSM) technique was applied to a 1-mm thick AZ31 magnesium sheet. UNSM is a relatively new surface modification technique in which a hard, hemispherical tip (2.38 mm in diameter) strikes the surface at an ultrasonic frequency to induce plastically deformed gradient microstructures and deep compressive residual stresses through the thickness. After the UNSM treatment, the through-thickness microstructures were thoroughly investigated using electron microscopy and electron backscatter diffraction analysis. The through-thickness microstructures revealed zones that were severely deformed (down to 200 µm from the surface) and twin-dominated (200~300 µm deep from the surface). The severely deformed zone consisted of shear banding, grain subdivision and reorientation, due to the strong plastic deformation, accompanied by the formation of {10<math xmlns="http://www.w3.org/1998/Math/MathML"><mover accent='true'><mn>1</mn><mo>−</mo></mover></math>2} tensile twins (despite compressive strikes by the hemispherical tip), {10<math xmlns="http://www.w3.org/1998/Math/MathML"><mover accent='true'><mn>1</mn><mo>−</mo></mover></math>1}-{10<math xmlns="http://www.w3.org/1998/Math/MathML"><mover accent='true'><mn>1</mn><mo>−</mo></mover></math>2} double twins and {10<math xmlns="http://www.w3.org/1998/Math/MathML"><mover accent='true'><mn>1</mn><mo>−</mo></mover></math>1} compression twins. The cause for tensile twinning was examined through a literature survey. In the twin-dominated zone, the twining activity prevailed as the slip activity gradually decayed through the thickness. The UNSM-induced hardness and microstructure enhancement was found to be effective down to about 300~400 μm deep from the surface. Finally, the source of the increase in yield strength after the UNSM treatment of the AZ31 sheet was analyzed, and focused on individual cases of microstructural enhancement in the severely deformed zone and the twin zone, and the compressive residual stress.

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42

Wang, Lei, Zi-mei Dong, Guang-wen Chen, Ronald Sluys, and De-zeng Liu. "Integrative descriptions of two new species of Dugesia from Hainan Island, China (Platyhelminthes, Tricladida, Dugesiidae)." ZooKeys 1028 (April 5, 2021): 1–28. http://dx.doi.org/10.3897/zookeys.1028.60838.

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Two new species of the genus Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from Hainan Island of China are described on the basis of morphological, karyological and molecular data. Dugesia semiglobosa Chen & Dong, sp. nov. is mainly characterized by a hemispherical, asymmetrical penis papilla with ventrally displaced ejaculatory duct opening terminally at tip of penis papilla; vasa deferentia separately opening into mid-dorsal portion of intrabulbar seminal vesicle; two diaphragms in the ejaculatory duct; copulatory bursa formed by expansion of bursal canal, lined with complex stratified epithelium, which projects through opening in bursa towards intestine, without having open communication with the gut; mixoploid chromosome complement diploid (2n = 16) and triploid (3n = 24), with metacentric chromosomes. Dugesia majuscula Chen & Dong, sp. nov. is mainly characterized by oviducts opening asymmetrically into female reproductive system; hyperplasic ovaries; expanded posterior section of bursal canal; vasa deferentia separately opening into mid-dorsal portion of seminal vesicle; asymmetrical penis papilla due to ventral course of ejaculatory duct, which has subterminal and dorsal opening at tip papilla; mixoploid chromosome complement diploid (2n = 16) and triploid (3n = 24); chromosomes metacentric. Apart from their anatomy, separate species status of the two new species is supported also by their genetic distances and by their positions in the phylogenetic tree. The sexualization process may have been induced by the lower temperatures, in comparison with their natural habitat, under which the worms were cultured in the laboratory.

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43

DAVIES, KERRIE, ROBIN GIBLIN-DAVIS, WEIMIN YE, GARY TAYLOR, and KELLEY THOMAS. "Nematodes from galls on Myrtaceae. II. Fergusobia/Fergusonina from small axillary bud ('stem') and leaf ('pea') galls in Australia, with descriptions of two new species." Zootaxa 3415, no. 1 (August 9, 2012): 1. http://dx.doi.org/10.11646/zootaxa.3415.1.1.

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Two new species of Fergusobia, collected from small multilocular axillary vegetative bud ('stem') and unilocular leaf 'pea' galls on, respectively, Eucalyptus camaldulensis from South Australia, and an unknown species of Corymbia growing in sub-coastal north-eastern NSW, Australia, are described. Fergusobia camaldulensae n. sp. Davies is characterized morphologically by an almost straight to open-C shaped parthenogenetic female with a broadly conoid tail, an arcuate infective female with a hemispherical tail tip, and males of varying shape with weakly sclerotised angular spicules and bursa arising at mid-body length. Fergusobia rileyi n. sp. Davies is characterized morphologically by the combination of an almost straight to arcuate parthenogenetic female with a broadly conoid tail, an arcuate infective female with relatively narrow tail with a pointed tip, and arcuate males with arcuate spicules, a relatively slender tail, and long peloderan bursa. These species are associated with larvae of undescribed fly species having dorsal shields of the 'transverse bars' form or lacking. Other apparently related forms of Fergusobia/Fergusonina associations from small 'stem' and 'shoot' galls and unilocular leaf 'pea' galls are reported, the larval shield morphology of their associated mutualistic fly species is discussed where known, and their possible relationships are outlined. DNA sequence analyses of the domain 2 and 3 segments of the large subunit rDNA gene (D2/D3) and mitochondrial DNA cytochrome oxidase subunit 1 (mtCOI) supported the new species status and their phylogenetic relationships with other sequenced species in Fergusobia.

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44

Yamane, Sôichi, and Yosiaki Itô. "Nest Architecture of the Australian Paper WaspRopalidia Romandi Cabeti, With a Note on its Developmental Process (Hymenoptera: Vespidae)." Psyche: A Journal of Entomology 101, no. 3-4 (1994): 145–58. http://dx.doi.org/10.1155/1994/92839.

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Nest architecture ofRopalidia romandi cabetiwas described, based on 2 incipient (an active and an abandoned) nests and 3 developed ones. Developed nests were spherical, or hemispherical when built under flat surfaces, consisted of several to more than 10 horizontal combs with oval or irregular shapes. Each comb was suspended by many pedicels from the upper one. Since several combs were simultaneously constructed at the same story, they often produced irregular interconnections that caused complex stair-like, or “semispiral” structures. Combs were entirely surrounded by an outer envelope with a small entrance hole at the lower tip. The envelope was probably constructed after the first group of combs had been completed. Materials for both cells and envelope were plant fibers glued together with salivary secretion. The surface of envelope was more thickly coated with the secretion than cell walls. The largest nest had about 30,000 cells in more than l0 stories of combs that had a surface area of 1,933 cm2. Its dimensions were 21.5 cm in longer diameter and 17.5 cm in height.

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45

García-Rodríguez, R., and G. Díaz-Rodríguez. "Parallel-Distributed Model Deformation in the Fingertips for Stable Grasping and Object Manipulation." Mathematical Problems in Engineering 2012 (2012): 1–22. http://dx.doi.org/10.1155/2012/949834.

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The study on the human grip has inspired to the robotics over the past decades, which has resulted in performance improvements of robotic hands. However, current robotic hands do not have the enough dexterity to execute complex tasks. Recognizing this fact, the soft fingertips with hemispherical shape and deformation models have renewed attention of roboticists. A high-friction contact to prevent slipping and the rolling contribution between the object and fingers are some characteristics of the soft fingertips which are useful to improve the grasping stability. In this paper, the parallel distributed deformation model is used to present the dynamical model of the soft tip fingers withn-degrees of freedom. Based on the joint angular positions of the fingers, a control scheme that fuses a stable grasping and the object manipulation into a unique control signal is proposed. The force-closure conditions are defined to guarantee a stable grasping and the boundedness of the closed-loop signals is proved. Furthermore, the convergence of the contact force to its desired value is guaranteed, without any information about the radius of the fingertip. Simulation results are provided to visualize the stable grasping and the object manipulation, avoiding the gravity effect.

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46

Esfahani, Javad Moftakharian, Masoud Esfandeh, and Ali Reza Sabet. "Effect of Nanoclay on Quasi Static Perforation of Thin-walled Polymer Composite Laminates." Polymers and Polymer Composites 20, no. 8 (October 2012): 737–48. http://dx.doi.org/10.1177/096739111202000809.

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In this study, the penetration and perforation performance of nanoclay reinforced unsaturated polyester resin/fibreglass nanocomposite laminates have been investigated via quasi-static indentation tests using ahemispherical nose indenter. Unsaturated polyester resin (UP) was mixed with 1.5 and 3 wt.% nanoclay using a homogenizer stirrer to prepare a homogeneous mix. UP reinforced nanocomposite was then utilized to manufacture 150 × 150 mm2 laminated composite panels using 400 g/m2 glass fibre woven roving via a hand lay-up process. X-ray diffractometry, transmission electron microscopy analysis, energy-dispersive X-ray (EDXA) analysis and measurement of viscosity changes in the liquid state resin confirmed the exfoliation and the intercalation of the nanoclay by the unsaturated polyester resin system used. Quasi-static perforation tests were conducted using a surface-hardened steel indenter with a hemispherical tip at 5 and 500 mm/min load rates on nanocomposite laminated plates. Measurement of the quasi-static force as a function of indenter displacement for all the specimens showed four distinct regions, namely penetration, perforation, exit and residual frictional force. The results indicated a clear role being played by the nanoclay filler as a secondary reinforcement, in terms of higher energy absorption in all four regions.

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47

Wang, Jianyao, Zhuyong Liu, and Jiazhen Hong. "Numerical and Experimental Investigations on a Three-Dimensional Rod-Plate Impact." Shock and Vibration 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/6720186.

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There are a few numerical simulation methods available for impact problems. However, most numerical results are not validated experimentally. The goal of this paper is to examine how well the simulation results correspond to the physical reality. In this work, normal and oblique impacts of a hemispherical-tip rod on a square plate are investigated both numerically and experimentally. In the numerical approach, finite element method is used to discretize the contact bodies to describe the deformation precisely combined with the floating reference frame method to describe the rigid motion. In the experimental study, strain gauges and Laser Doppler Vibrometers are employed to measure the high-frequency impact responses. Detailed comparative studies between numerical and experimental results are performed. In the case of normal impact, great attention is given to investigate the influence of finite element mesh size on the simulation accuracy and a “Prediction-Refinement” discretization strategy is proposed for obtaining a mesh which is optimal for impact dynamics. In the case of oblique impact, the influence of Coulomb’s friction coefficient is investigated additionally. It shows that the numerical results are in good agreement with the experimental results for both normal and oblique impacts.

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48

Mandal, Himadri, Shubhendu Maiti, Tien-Lung Chiu, and Sankar Gangopadhyay. "Mismatch considerations in laser diode to single-mode circular core triangular index fiber excitation via upside down tapered hemispherical microlens on the fiber tip." Optik 168 (September 2018): 533–40. http://dx.doi.org/10.1016/j.ijleo.2018.04.115.

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49

Babitsky, L. F., and V. Yu Moskalevich. "Bionics in the Development of Agricultural Machines Taking into Account the Processed Material and the Created Devices Properties in Determining Characteristics." Herald of the Bauman Moscow State Technical University. Series Instrument Engineering, no. 1 (142) (March 2023): 4–14. http://dx.doi.org/10.18698/0236-3933-2023-1-4-14.

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The paper considers development of the new area in agricultural engineering, i.e., bionics. The purpose of the work is to elaborate methodology and technical means for determining the soil deformation index as a new characteristic of its physical and mechanical properties, which makes it possible to pass directly from the processed materials deformation properties to the shape of the working surfaces of machines created in similarity to the living dorbeetle organisms. The soil deformation index is the deformer area per unit of critical pressure on the soil. When describing the soil behavior in the deformation process, the paper proposes to use this indicator in the rheological models. The method for determining the soil deformation index provides for a smooth indentation of a hemispherical tip into the soil or earth with simultaneous fixation of its immersion depth into the soil and of the force required in penetrating to this depth. Registration of these parameters is possible both on paper in the form of a diagram and electronically in the digital form. A device for the soil deformation index determination is considered, it includes a laboratory unit with the hydraulic drive, a microscope-based unit for bionic research and a device for working in the field

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50

Davies, Kerrie A., Gary S. Taylor, Weimin Ye, Jeffrey R. Makinson, and Robin J. Adair. "First record of Fergusonina (Diptera: Fergusoninidae) and associated Fergusobia (Tylenchida: Neotylenchidae) forming galls on Leptospermum (Myrtaceae) in Australia, with descriptions of new species." Insect Systematics & Evolution 49, no. 2 (April 13, 2018): 183–206. http://dx.doi.org/10.1163/1876312x-00002166.

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A new species of fly, Fergusonina madidum Taylor sp.n. (Diptera: Fergusoninidae) from Leptospermum madidum A.R. Bean in far north Queensland and a new species of nematode, Fergusobia leptospermum Davies sp.n. (Tylenchida: Neotylenchidae) from L. laevigatum (Gaertn.) F. Muell. in southern Victoria, Australia are described. These represent the first species of the Fergusonina fly/Fergusobia nematode mutualism to be described from the genus Leptospermum (Myrtaceae). Fergusonina madidum sp.n. forms lateral and terminal multilocular shoot bud galls enclosed in subterminal leaflets. It can be distinguished from all other species of Fergusonina by the lack of dorsal setae on abdominal segment 7 of the female. Unlike most described species of Fergusonina it also lacks the posterior cross vein m-cu in the wing. It shares this character with F. giblindavisi Taylor and F. thomasi Taylor from flower bud galls on Corymbia, but both these species are large and abdominal segment 7 of females is densely setose. Its larva is unknown but from the morphology of puparia the dorsal shield comprises 3 broad transverse bands comprising lateral rows of raised ridge-like sclerotised spicules. Its associated species of nematode is not known. Fergusobia leptospermum sp.n. is associated with cryptic lateral and terminal usually unilocular shoot bud galls. It is characterised by the combination of an open to tight C-shaped parthenogenetic female having a small ‘a’ ratio, with a short but sturdy stylet, flat anterior end; huge dorsal pharyngeal gland, reproductive system with a relatively long uterus, and a sub-conoid tail with a broadly rounded tip; a C-shaped infective female with an almost hemispherical tail tip which may or may not be ventrally hooked; and an open C-shaped male with angular spicules and peloderan bursa arising near the anterior end, and a relatively long (c’ = 2.2–3.2) sub-conoid tail with a bluntly to broadly rounded tip. Its status as a distinct species is confirmed by molecular analyses. Its associated species of fly is known only from several larvae and a puparium, and remains undescribed. The dorsal shield of this Fergusonina species comprises 7 broad bands, the first six having heavily sclerotised raised ridges and the seventh with a medial field of weak spicules. The widely separated collection localities, together with the large number of species in Leptospermum suggest that the mutualism is likely to be speciose and occupy a broad geographic range on this host.

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Journal articles on the topic 'HEMISPHERICAL TIP'

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