Line Groove Research Articles

Cirurgia cardíaca videoassistida: resultados de um projeto pioneiro no Brasil

To demonstrate the possibilities of the use of videothoracoscopy in cardiac surgery using cardiopulmonary bypass (CPB). Between February 2006 and November 2008, 102 patients underwent consecutively minimally invasive video-assisted cardiac surgery. The cardiac pathologies approached were: mitral valvopathy (n=56), aortic (n=14), interatrial communication (IC) (n=32), six patients presented associated tricuspid insufficiency and 12 presented atrial fibrillation. The age ranged from 18 to 68 years and 57 were female. The surgical approach was: femoral arterial and venous cannulation, minithoracotomy ranging from four to six centimeters (cm) at the level of the 3 degrees or 4 degrees right intercostal space (RICS), depending on the pathology of the patient, between anterior axillary line and hemiclavicular line, submammary or right periareolar groove through the right breast and thoracoscopy. The surgical procedures were: plasty (n=20) or mitral valve replacement (n=36), aortic valve replacement (n=14), atrioseptoplasty using pericardial patch (n=32), tricuspid valve repair with rigid ring (n=6) and surgical correction of atrial fibrillation with radiofrequency (n=12). There were no complications during the procedures. There was no conversion to thoracotomy in neither case. Two patients developed atrial fibrillation in the postoperative period. There was an episode of stroke seven days after the hospital discharge and one death (0.9%) due to systemic inflammatory response syndrome (SIRS). This study demonstrates the coverage of pathologies that are possible to be approached by video-assisted cardiac surgery with cardiopulmonary bypass being a safe and effective procedure with low morbimortality. Minimally invasive video-assisted cardiac surgery is already a reality in Brazil, demonstrating excellent aesthetic and functional results.

Femtosecond laser micromachining of an Au/Cr film nanostack

Selective laser patterning of thin films in a multilayer structure is an emerging technology for the fabrication of MEMS devices. A 775-nm Ti:sapphire laser (130 fs, 1 kHz) was used to irradiate thin-film stacks with variations in the process parameters, such as the pulse energy, feed rate, and numerical aperture of the objective lens. The two layers of the Au/Cr film have the same thickness, which is about 1000 nm. They were coated on a glass substrate. By SEM, an AFM and an optical surface profiler, we investigate the morphology of a pattern including the line width, groove depth, and laser-induced periodic surface structures (LIPSSs). The ablation depth was observed to depend on the pulse energy. In addition, from the energy spectrum, we find which layer was removed completely. The experimental results show that precise micromachining with a desired stability and reproducibility can be achieved by controlling the ablation energy and the feed rate. With a different energy and feed rate, we have processed the gating and the circle, which with the smooth cutting edge and groove was consistent with the beam spatial distribution.

Experimental Investigation on Friction Performance of Mechanical Seals with a Laser-Textured Seal Face

Regular micro-surface structure in the form of micro-pores produced on the face of mechanical seals by laser technology can be used to improve the friction performance of the seal mating rings. A test rig with variable axial load was used to test laser-textured seal rings with micro-pores of various pore depth and pore ratio to study the effect of the laser-textured seal face structure parameters on the friction performance of mechanical seals. It is found that there are optimum texturing face parameters at which the friction torque and the face temperature rise of seal rings are minimum. Results of these tests show that the micro-pores on one of the seal mating faces can generate substantial hydrodynamic effect. Heat generation due to frictional contact on seal-ring surfaces is a major factor that causes deterioration of face seals and shortens their service life[1,2]. Excessive temperature rise can be avoided by improving structure of a seal surface. By means of laser technology return-flow structure, oblique line groove and spherical micro-pores are engraved on the seal face[3-5]. The research shows that substantial hydrodynamic effect can be generated between the seal faces with micro-pores[6-8]. In this study experiments are performed on laser-textured micro-pores seal faces at various axial loads to investigate the effect of the face structure and operating parameters on friction torque and face temperature rise.

Powder Blasting 에 의한 유리의 미세 홈 가공시 노즐 주사횟수의 영향

The old technique of sandblasting which has been used for decoration of glass surface has recently been developed into a powder blasting technique for brittle materials such as glass. silicon and ceramics. capable ofbr/ producing micro stmctures larger than lOO㎛. This paper describes the performance of powder blasting technique in micro-line grooving of glass and the effect of the number of nozzle scanning on the depth and width of line groove. Experimental results showed that increasing the no. of nozzle scanning resulted in the increase of depth and width in grooves. Increase of width which may cause several problcms in the precision machining results from wear of mask film. Therefore. well-controlled masking process is the most important factor for micro machining of glass with accuracy.

Stripe stabilization in vertical Bloch line memory

Partially grooved, long, rectangular grooves on the garnet surface were used to stabilize minor loop stripes in a vertical Bloch line memory. These stripes reside beneath the stripe confinement groove. The test chip contained 10 or 20 minor loop grooves, 10 read/write (r/w) gate grooves, and a major line groove. The film thickness was 4.76 μm, and the groove was 0.5 μm deep. Each minor loop groove was 500 μm long, four widths were tried: 3.5, 4, 4.5, and 5 μm. Two groove periods were tried: 10 and 20 μm. For stripe initialization, a bubble was nucleated in every minor loop groove by a single current pulse at a 90 Oe bias field. As the bias field was decreased slowly, bubbles began to stripe out at 80 Oe. At 75 Oe, all 10 stripes were stretched to the full groove length. These stripes were stable at bias fields between 70 and 80 Oe. Stripes decreased in length at higher fields, and escaped from the confinement groove at low fields. When stripes escaped from the groove, it always occured from the end not facing a r/w gate groove. These bias field values and the stripe-escape asymmetry are confirmed by computer simulation.

片面狭開先ＭＡＧ溶接法の研究 ＩＩＩ 裏波制御溶接方法の開発

The authors have been carrying out practical studies on one-side narrow-gap MAG with DCEN polarity. In the previous paper, observation of Uranami bead shapes and determination of suitable range of condition for Uranami Welding were carried out and it was made clear that Uranami beads without defect could be achieved over a wide range of conditions with this method. However, in case of long weld line and changing groove width, it became clear too that fine adjustment of conditions (mainly adjustment of speed) would be necessary in order to achieve constant shapes of Uranami bead all along the weld line.Consequently, the relationships between arc phenomena in Uranami welding and shapes of Uranami bead were observed, and it was found that the shape of the Uranami bead was dependent on the speed and the wave pattern of the current. Based on these results, a new Uranami welding control method was developed. In this method, a control signal which was obtained by monitoring the current with a micro-computer, was used to adjust the speed continuously in order to achieve a good Uranami bead.Application of this control system to one-side narrow-gap MAG with DCEN polarity confirmed that uniform Uranami beads could be obtained even if the root gap varies from 9 to 12 mm.

Dielectric image line groove antennas for millimeter waves, Part I: Theoretical background

Dielectric image line groove antennas are very useful for the application in the millimeter-wave region. In this first part of a two-part paper, three different types of groove discontinuities under a dielectric image line for application in millimeterwave antennas are investigated: the equivalent circuits of 1) a slot discontinuity in a metallic ground plane and 2) a slot discontinuity in the metallization of a substrate material under a dielectric image line are derived theoretically using an approximation for the electromagnetic fields of the slots. 3)The equivalent circuit of cylindrical holes in a metallic ground plane under a dielectric image line is derived from measurements. The results are used to synthesize millimeterwave dielectric image line antenna arrays as described in part II of the paper.

標準尺測定の際の傾斜照明の影響

An analysis is given of a systematic error in the measurement of standard scales, the positional shift of graduation line images produced by the micrometer-microscope, which is caused by the imperfect adjustment of the illuminating system of the microscope. Many experiments show that the amount of the shift is nearly proportional to the incident angle of illuminating light to the graduated surface within a range of 3°. This paper point out two causes of the shift. The one is imperfect focusing of the graduation line image which is analyzed theoretically. The other is related to the micro-geometrical form of the line groove and it is found that the aspect of the shift is very complicated. However, the line on metal surface, ruled with a diamond tool has larger shift than that of the line on glass surface coated by a thin metallic film.

The Technique of the Boyne Carvings

The prudent contributor to a Festschrift will select some subject about which he thinks he knows as much as the professor who is to receive it. That is peculiarly difficult here because of the vast range of Professor Childe's knowledge, both in time and space, far exceeding the present contributor's. This Note is offered as a grateful tribute from one of the many who have been intellectually enriched by his writings and encouraged by his devotion to scholarship. It is little more than an amplification and criticism of the Abbé Breuil's classic Presidential Address to the Prehistoric Society of East Anglia, delivered in 1934; but on the strength of observations made in August and September, 1955, I have come to different conclusions.The Abbé Breuil detected five successive techniques, all of them found on the stones of the Boyne Tombs:(1) Incised thin lines (pl. XIX, B).(2) Picked grooves left rough (pl. XVIII).(3, a) Picked grooves afterwards rubbed smooth; in this and the preceding group ‘it is invariably the line (groove) itself on which the pattern depends, which gives and is the design’.(3, b) Picked areas which ‘only define the limits of the pattern, the surface, left in relief by the cutting down of the background, constituting the actual design’ (pl. xx, B).(4) Rectilinear patterns where also the pattern is residual, consisting of raised ribs, forming triangles or lozenges, left standing by picking away the surrounding surface (pl. xx, A).