Position Of Groove Research Articles

Large-scaled line plasma production by evanescent microwave

Long line-shaped microwave plasma has been generated, in helium and argon gas pressure, over a pressure range of 1–50 torr. To this end, waves of 2.45 GHz are fed into a narrow flat rectangular waveguide, through a tapered waveguide. The power of microwave is coupled to the discharge gas through a linear-slot antenna. The discharge is realized in a rectangular Pyrex tube, placed-in along the slot groove position. In this configuration the microwave is cut off, but the evanescent wave with a long wavelength is propagated and employed to produce the plasma. Measurements of the field distribution in the waveguide revealed that the wavelength of the excited field increases as waveguide width decreased to a width close to the cut-off width of 61.3 mm. The relative intensities of He I lines show very high uniformity along the whole line plasma length, and helium excitation temperatures were in the range of 3000–5000 K.

Heat Transfer and Friction Characteristics Optimization with Compound Turbulators in Roughened Ducts

AbstractThe use of artificial roughness or turbulence promoters on a surface is an effective technique to enhance the rate of heat transfer of the fluid flowing in a duct. In this study, a computer code has been developed to perform a numerical simulation for optimizing the shape of two-dimensional channel with periodic ribs mounted on the bottom wall to enhance turbulent heat transfer. The Reynolds-Averaged Navier-Stokes analysis is used as a numerical technique and the SST k-(ω) turbulent model with near-wall treatment as a turbulent model. The simulations were performed for two rib shapes, trapezoidal with decreasing height in the flow direction with and without grooves between the ribs. The results are validated by comparing with existing experimental data and semi-empirical correlations. The Reynolds number, pitch-to-rib high ratio and relative groove position are chosen as design variables. The effects of roughness parameters on Nusselt number and friction factor have been discussed and the conditions for the best performance have been determined and presented.

Numerical Simulation and Experiment of Self-Piercing Riveting with Solid Rivet Joining Multi-Layer Aluminum Sheets

Numerical simulation and experiment of self-piercing riveting with solid rivet joining multi-layer aluminum sheets are carried out in this paper. The forming process of the riveting and the distribution of stress are analyzed, the results show that the simulation is consistent with the experiment. The results of experiment prove that the transition point of the cone-shaped head of the solid rivet, the size and position of groove affect directly the quality of riveting. The fillet at the transition point of the cone-shaped head of the solid rivet can decline the maximum stress of the rivet. When the distance between the center of groove and bottom of rivet is about three quarters of the bottom sheet thickness, the bottom sheet of self-piercing does not fall off. The self-piercing riveting with solid rivet joining multi-layer aluminum sheets is feasible.

Thermo-hydrodynamic performance of grooved oil journal bearing

Steady state thermo-hydrodynamic analysis and its comparison at five different feeding locations of an axial grooved oil journal bearing is obtained theoretically. Reynolds equation is solved simultaneously along with the energy equation and heat conduction equation in bush and shaft. From parametric study it is found that 12° feeding groove position is better in comparison to other feeding locations. Feeding from the bottom is very less preferable since the load capacity is lesser and temperature development is more. It is very difficult to obtain the solution due to numeric instability when the bearing operates at higher eccentricity ratio.

Influence of groove in metallic subwavelength slit on transmission properties

The influence of the structure and position of groove in a two-dimensional metallic subwavelength slit on transmission properties has been studied with the finite-difference time-domain method. The whole structure of slit with perpendicular groove could be regard as a LC oscillation circuit. The capacitance and inductance of this oscillation circuit will be altered when the structure of groove varies，so that the resonant transmission peaks shift. And the drive source of circuit changes when the position of groove moves along the slit, as a result the distribution of electromagnetic filed in the structure is changed also. So the resonant transmission peaks are split. In this paper， the change of resonant transmission peaks as each parameter of the groove changes is analyzed with the principle of LC resonance.

Comparative study of larval head structures of Megaloptera (Hexapoda)

External and internal head structures of the larva of Neohermes are described in detail. The results are compared to conditions found in other representatives of Corydalidae, in Sialidae, and in Raphidioptera and Neuroptera. Corydalidae and Sialidae are mainly characterised by plesiomorphic features such as distinct frontal and coronal sutures, six stemmata, a movable labrum with a full set of muscles, a thin tentoriomandibular muscle, a distinct maxillary groove, 4-segmented maxillary palps, an oblique arrangement of the extrinsic maxillary muscles, a labium with all components except for the glossae and paraglossae, 3-segmented labial palps, and a largely complete muscle system. The partly reduced maxillary groove, the strongly elongated stipes, the apical membranous stipital collar, the close connection of the palp and galea, the subdivision of the galea, the strongly shortened palp, the bipartite tentoriocardinal and tentoriostipital muscles, the anterolateral submental notch, the lateral tentoriopharyngeal muscle, and the postgular plate are autapomorphies of Corydalidae. An additional antennomere is present in large corydalid species. The monophyly of the subfamilies Corydalinae and Chauliodinae is not supported by features of the larval head. The reduced condition of the anterior and dorsal tentorial arms and the antennal muscles, the transverse labial muscle, the loss of muscles of the salivary duct, and possibly the lateral origin of M. frontopharyngalis posterior are autapomorphies of Sialidae. The monophyly of Megaloptera is suggested by the insertion of a peg-like or spine-shaped sensillum on the antepenultimate antennomere, the vestigial salivary duct, and a verticopharyngeal muscle composed of several bundles. The distinct neck region, the parietal ridge, and the anterior position of the posterior tentorial grooves are features shared by Corydalidae and Raphidioptera. Arguments in favour of a clade comprising Megaloptera and Raphidioptera are the presence of a circular ridge anterad of the neck region, an increased number of Semper cells and retinula cells in the stemmata, the presence of a gula in adults, a similar cleaning behaviour, and molecular data. Potential autapomorphies of Neuropterida are the prognathism of the larvae and the absence of a mandibular mola. However, the polarity of these characters is unclear. A derived condition found in most groups of Endopterygota, but not in Hymenoptera, is the presence of one or two sensorial appendages on one of the intermediate antennomeres, usually the penultimate. Larval autapomorphies of Endopterygota suggested in earlier studies are confirmed for Corydalidae.

Fabrication of SiC particle reinforced composite on aluminium surface by friction stir processing

A feasibility investigation has been carried out of the formation of surface composite by uniformly distributing SiC particles 1˙25 µm in size into a surface layer of an A 1050-H24 Al plate through friction stir processing (FSP). The SiC particle was filled into a groove cut on the Al plate, covered by an Al sheet 2 mm thick, and a rotating tool was penetrated from the cover sheet so that the probe tip reached a depth beyond the groove bottom. The effects of process parameters (rotation speed and travelling speed) and applying multiple passes on the distribution of SiC particle in the nugget zone were investigated. The effects of groove size and its position relative to the tool probe were also investigated. Applying multiple passes had a great effect on the homogeneity of the SiC particle distribution. At rotation speeds of 2000–3000 rev min−1, the SiC particles tended to cluster in some places in the nugget zone. By decreasing the rotation speed to 1000–1500 rev min−1, the SiC particle was distributed in almost all the nugget zone area when the groove was 2–3 mm wide and 1˙5 mm deep. On the other hand, the stirring action of FSP was insufficient to distribute homogenously the SiC particles when the groove size was increased to 3×2 mm. By shifting the groove position towards the advancing side of the tool probe, the distribution of the SiC particles in the nugget zone became better. The defect free nugget zone with homogenously distributed SiC particles was obtained in a sample produced by FSP at rotation speeds of 1500 rev min−1 for the first pass and 1250 rev min−1 for the second and third passes. Microhardness of the nugget zone was increased to a level as high as 55 HV when the groove size was 3×1˙5 mm. The effect of the rotation speed on the particles dispersion was discussed with particular reference to the vertical material flow in the nugget zone.

Axial piston pump grooved slipper analysis by CFD simulation of three-dimensional NVS equation in cylindrical coordinates

This paper presents static and dynamic characteristics of a piston pump slipper with a groove. Three-dimensional Navier Stokes equations in cylindrical coordinates have been applied to the slipper/plate gap, including the groove. The paper presents pressure, leakage, force and torque variations when groove dimensions and position are being modified, the effect of slipper tangential velocity and turning speed are also considered. Fluid momentum interchange inside the groove is studied, since vorticity inside the groove is analysed under several working conditions. A test rig was build to compare experimental and CFD results, finding a good agreement for all of the cases studied. Flow is considered laminar and incompressible under all conditions and the slipper is considered parallel to the plate. Design instructions to optimise slipper/groove performance are also given.

Specification and positioning of parasegment grooves in Drosophila

Developmental boundaries ensure that cells fated to participate in a particular structure are brought together or maintained at the appropriate locale within developing embryos. Parasegment grooves mark the position of boundaries that separate every segment of the Drosophila embryo into anterior and posterior compartments. Here, we dissect the genetic hierarchy that controls the formation of this morphological landmark. We report that primary segment polarity genes ( engrailed, hedgehog and wingless) are not involved in specifying the position of parasegment grooves. Wingless signalling plays only a permissive role by triggering the formation of grooves at cellular interfaces defined by the ON/OFF state of expression of the earlier acting pair-rule genes eve and ftz. We suggest that the transcription factors encoded by these genes activate two programmes in parallel: a cell fate programme mediated by segment polarity genes and a boundary/epithelial integrity programme mediated by unknown target genes.

The false and the true bifid condyles

The bifid mandibular condyle has been described as a condition of unknown ætiology and uncertain pathogenesis. Many see it as the product of accidental trauma or forceps delivery, with the two heads occurring one behind the other in the sagittal plane. In bioanthropological literature, “bifid condyle” often describes pitting in the sagittal plane, dividing the condyle mediolaterally. We examined 38 male and 16 female pre-European-contact Pacific islanders’ adult mandibles, and 24 male and 29 female modern Indian mandibles, recording frequency, prominence and position of any condylar groove in both coronal and sagittal planes. We report the tenth known case of a bilaterally-bifid condyle. A groove was found almost twice as likely to occur on the left condyle of the Indians than of the Pacific Islanders, but equally likely to occur on the right side of both groups. That same finding applied to males and females. In order to avoid terminological ambiguity, we suggest that the term “bifid condyle” should be reserved for describing multiple condyles in the sagittal plane only – the true bifid condyle. An hypothesis is offered for the occurrence of the groove in the sagittal plane.

DEFECT DETECTION WITHIN A PIPE USING ULTRASOUND EXCITED THERMOGRAPHY

An UET (ultrasound excited thermography) has been used for several years for a remote non-destructive testing in the automotive and aircraft industry. It provides a thermo sonic image for a defect detection. A thermograhy is based On a propagation and a reflection of a thermal wave, which is launched from the surface into the inspected sample by an absorption of a modulated radiation. For an energy deposition to a sample, the UET uses an ultrasound excited vibration energy as an internal heat source. In this paper the applicability of the UET for a realtime defect detection is described. Measurements were performed on two kinds of pipes made from a copper and a CFRP material. In the interior of the CFRP pipe (70mm diameter), a groove (width - 6mm, depth - 2.7mm, and length - 70mm) was engraved by a milling. In the case of the copper pipe, a defect was made with a groove (width - 2mm, depth - 1mm, and length - 110 mm) by the same method. An ultrasonic vibration energy of a pulsed type is injected into the exterior side of the pipe. A hot spot, which is a small area around the defect was considerably heated up when compared to the other intact areas, was observed. A test On a damaged copper pipe produced a thermo sonic image, which was an excellent image contrast when compared to a CFRP pipe. Test on a CFRP pipe with a subsurface defect revealed a thermo sonic image at the groove position which was a relatively weak contrast.

Bone Landmarks Are More Reliable Than Tensioned Gaps in TKA Component Alignment

Two distinct techniques have been used to achieve alignment and ligament balance in TKA. We hypothesized a bone landmark technique would result in normal alignment, stability, and load-bearing characteristics and that the tensioned gap technique results in malalignment. We studied 12 normal cadaveric knees (six with each technique) for stability, alignment, load-bearing stress transfer characteristics, and patellar groove position after TKA. The tensioned gap technique used tensioners to establish equal loads in the medial and lateral ligaments at 90 degrees flexion and to resect the posterior femoral surfaces parallel to the cut tibial surfaces. The bone landmarks technique aligns the anterior and posterior femoral cuts perpendicular to the median sagittal plane as defined by the anteroposterior axis and then resects bone to match implant thickness. The tensioned gap technique maintained nearly equal laxity medially and laterally but the knee shifted into varus malalignment in flexion. Compressive stress in the knee shifted medially in flexion, and the patellar groove shifted laterally. The bone landmarks technique produced near normal varus and valgus and rotational stability; alignment, patellar groove position, and load transfer characteristics remained near normal throughout flexion.

Heat transfer and friction characteristics for artificially roughened ducts with compound turbulators

An experimental investigation on heat and fluid flow characteristics of fully developed turbulent flow in a rectangular duct having repeated integral transverse chamfered rib-groove roughness on one broad wall has been carried out. Experiments encompassed the Reynolds number range of 3000–21,000; relative roughness pitch of 4.5–10, chamfer angle of 5°–30°, relative groove position of 0.3–0.6 and relative roughness height of 0.022–0.04. The effect of roughness parameters on Nusselt number and friction factor have been discussed and the results are compared with the results of square rib-grooved and smooth duct under similar flow conditions. The conditions for the best performance have been determined. Correlations for the Nusselt number and friction factor have been developed as a function of roughness parameters and flow Reynolds number.

Second law optimization of a solar air heater having chamfered rib–groove roughness on absorber plate

Artificially roughened solar air heaters perform better than the plane ones under the same operating conditions. However, artificial roughness leads to even more fluid pressure thereby increasing the pumping power. The entropy generation in the duct of solar air heater having repeated transverse chamfered rib–groove roughness on one broad wall is studied numerically. Roughness parameters, viz., relative roughness pitch P/ e, relative roughness height e/ D h relative groove position g/ P, chamfer angle φ and flow Reynolds number Re have a combined effect on the heat transfer as well as fluid friction. The entropy generation is minimized and reasonably optimized designs of roughness are found.

Development of the profile ring rolling process for large slewing rings of alloy steels

In this study, a profile ring rolling process for large slewing rings of alloy steels is developed. A profile ring with a round groove located asymmetrically on the outside is rolled. The process is simulated by finite element method. General-purpose commercial finite element analysis software, MSC.SuperForm, is used. Experiments are carried out at an industrial ring rolling machine and compared with the analysis. By choosing the method that the height in the axial direction of the initial ring blanks is set higher than products and lowered by using conical rolls during the process, it is attempted to develop process to make a large slewing ring at a single ring rolling operation. To do this, the process is analyzed using the finite element analysis method and an experiment to make the real profile ring is carried out. In the case that the round groove on the outside is located at upper side, the position of the round groove moves downward and sidewall tilts. This phenomenon is predicted relatively well at the finite element analysis. It is recommended that the round groove on the outside is located at lower side.

The trochlea is medialized by total knee arthroplasty: An intraoperative assessment in 61 patients

Background A medialization of the femoral component in a total knee arthroplasty (TKA) causes abnormal patellar tracking, which could result in patellar instability, pain, wear, and failure. Previous reports defined medialization in relation to the neutral position of the femoral component, but omitted to compare it to the anatomical position of the trochlea. We assessed intraoperatively whether there is a systematic error of the position of the prosthetic groove relative to the anatomical trochlea.Material and methods A special instrument was developed to measure consecutively the mediolateral position of the anatomical trochlea and the mediolateral position of the prosthetic groove. 3 experienced knee surgeons determined the mediolateral error of the prosthetic groove in primary TKAs in 61 patients.Results There was a significant medial error of the prosthetic groove relative to the preoperative position of the trochlea, with a mean medial error of 2.5 mm (SD 3.3)Interpretation Our findings indicate that the trochlea is medialized by TKA. Because a conscious medialization of the femoral component in a TKA produces abnormal patellar tracking patterns, further investigations will be needed to analyze the clinical consequences of this medialization of the trochlea.

CT changes after trochleoplasty for symptomatic trochlear dysplasia

Trochlear dysplasia is an important risk factor for patellar instability. Because of a decreased trochlear depth in combination with a low lateral femoral condyle, the patella cannot engage properly in the trochlea. Trochleoplasty is a surgical procedure, which strives to correct such bony abnormalities. The aim of this study was to describe morphological features of trochlear dysplasia and the corrective changes after trochleoplasty on CT scan. The study group consists of 17 knees with trochlear dysplasia having undergone trochleoplasty for recurrent patellofemoral dislocation at a mean age of 22.4 years. The evaluation consisted in pre- and postoperative measurements on the proximal and distal trochlea on transverse CT scans in order to determine the morphological features. We measured the transverse position and depth of the trochlear groove, the transverse position of the patella, the ratio between the posterior patellar edge and the trochlear groove, the lateral patellar inclination angle, the sulcus angle, and the lateral trochlear slope. The trochlear groove lateralised a mean of 6.1 mm in the proximal aspect and 2.5 mm in the distal aspect of the trochlea, while the patella medialised a mean of 5 mm. Preoperatively the patella was lateral in relation to the trochlear groove in 13 cases, neutral in two cases, and medial in two cases. Postoperatively it was lateral in four cases, in neutral position in seven cases, and medialised in six cases, referenced to the trochlear groove. The trochlear depth increased from 0 to 5.9 mm postoperatively in the proximal aspect of the trochlea, and from 5.5 to 8.3 mm postoperatively in the distal trochlea. The lateral patellar inclination angle decreased from a mean of 21.9 degrees to a mean of 7.8 degrees . The sulcus angle decreased from a mean of 172.1 degrees to a mean of 133 degrees in the proximal trochlea and from a mean of 141.9 degrees to a mean of 121.7 degrees in the distal trochlea. The lateral trochlear slope changed from 2.8 degrees to 22.7 degrees in the proximal and from 14.9 degrees to 26.9 degrees in the distal part of the trochlea. In the CT scan patients with trochlear dysplasia demonstrated a poor depth, or even a flat or convex trochlea with a greater sulcus and lateral trochlear slope angle, a lateralised patella to the trochlear groove with poor congruency, and a greater lateral patellar inclination angle. Trochleoplasty can correct the pathological features of trochlear dysplasia by surgically creating more normal anatomy. The goal of this surgical procedure is to steepen and lateralise the trochlear groove for a better engagement of the patella.

A Laterally Positioned Concave Trochlear Groove Prevents Patellar Dislocation

Patellofemoral instability is a disabling condition that occurs in adolescence. Recurrence after patellar dislocation has been reported in 2-50% of patients. We compared the distal femur in patients with patellofemoral instability with distal femura of a healthy cohort using mathematical quantification of two-dimensional shape variation at the same position in different knees. One hundred eight computed tomography scans from 54 patients with patellofemoral instability were compared with 197 computed tomography scans from 102 subjects with normal knees. We used principal components analysis to quantify variation in shape of the trochlear groove as it allows comparison of knees with patellofemoral instability to healthy knees. We found that subjects who had dislocated their patella had a flattened trochlear groove, whereas normal knees had a more concave groove. The position of the trochlear groove was more medial in patients with patellofemoral instability compared with normal knees. Groove position was more important than shape when predicting which patellae were likely to dislocate.

Maximum slat width for cooling efficiency of horticultural produce in wooden crates

The influence of wood package design on airflow distribution was investigated for forced-air cooling using horticultural produce simulators. The position of grooves on the container walls was tested using slat width of 100–200 mm and airflow rates ranging from 0.0005 to 0.003 m 3 kg −1 s −1. The package opening configurations were compared based on their impact on the energy added to the system using a methodology previously developed. For this purpose, apples and sweet corns were taken as examples of produce from two different extremes in the respiration activity range. For airflow rates as low as 0.0005 m 3 kg −1 s −1one groove at the bottom of the container produced a cooling process more uniform than the other one-groove configurations and even two grooves because of natural convection effect. If packing low respiration rate produce, increasing airflow rate could compromise the process energy efficiency because of air circulation obstruction for less vented containers. For high respiration rate produce enlarging open area above 2.4% would be recommended rather than increasing airflow rate to enhance cooling energy efficiency.

Heat transfer and friction characteristics of rectangular solar air heater duct using rib-grooved artificial roughness

Experimental investigation on the heat transfer and friction characteristics of rib-grooved artificial roughness on one broad heated wall of a large aspect ratio duct shows that Nusselt number can be further enhanced beyond that of ribbed duct while keeping the friction factor enhancement low. The experimental investigation encompassed the Reynolds number range from 3000 to 21,000; relative roughness height 0.0181–0.0363; relative roughness pitch 4.5–10.0, and groove position to pitch ratio 0.3–0.7. The effect of important parameters on the heat transfer coefficient and friction factor has been discussed and the results are compared with the results of ribbed and smooth duct under similar flow conditions. The present investigation clearly demonstrates that the heat transfer coefficient for rib-grooved arrangement is higher than that for the transverse ribs, whereas the friction factor is slightly higher for rib-grooved arrangement as compared to that of rectangular transverse ribs of similar rib height and rib spacing. The conditions for best performance have been determined. Correlations for Nusselt number and friction factor have been developed that predict the values within reasonable limits.