Seam Length Research Articles

電磁圧接回路におけるインダクタンスの影響

Magnetic pulse welding is effective for lap-joining similar and dissimilar sheet metals such as Al/Al, Cu/Cu, and Al/Cu. A discharge circuit is used for the seam welding. It is composed of a flat one-turn coil and an energy-storing capacitor bank. The coil is an important component to obtain a high-density magnetic flux, and is made of one copper alloy plate, instead of a winding. The influence of the seam length of a sheet metal has been confirmed by welding an aluminum sheet to another aluminum sheet. It has been clarified that magnetic pulse welding is suitable for joining a sheet metal with increasing seam length, because the effective inductance increases with increasing seam length. As a result of investigating the transfer quantity of the electric energy from a capacitor to a coil, it has been found that magnetic pulse welding with a high energy efficiency can be used to join sheet metals if the transfer coefficient is large. On the basis of the experimental results, the influence of the remaining inductance on the transfer coefficient is calculated. A decrease in the remaining inductance adds to the welding capability of equipment and reduces the electric energy consumption.

Design and Testing of the Copper Pipe and Aluminum Pipe Welding Control System

The copper - aluminum pipe has been widely used in the refrigeration industry. And the welding quality becomes the focus. A PLC control system was developed to accurately control the resistance welding process of the Cu-Al pipe. The welding voltage was adjusted by a couple of silicon controlled rectifiers (SCR). To restrain the effect of network voltage fluctuation on the welding heat generation, it was obtained that the experimental relationship of the angle of flow and the network voltage, and fitted to a quadratic polynomial equation. Therefore, the control system can calculate the exactly the angle of flow value according to the current network voltage. The experiment results show that the error of the welding heat generation is limited in 5% when the network voltage fluctuates in the range of 380V ±10%. And the SEM and EDS analyzing results suggests that the welding seam length is more than 5mm, and there is hardly eutectic composition.

Skinning 3D meshes

A planar parameterization of 3D surfaces is useful for many applications. The applicability of the parameterization depends on how well it preserves the surface geometry (angles, distances, and areas). For most surface meshes there is no parameterization which preserves the geometry exactly. The distortion usually increases with the rise in surface complexity. For highly complicated surfaces the distortion can become so strong as to make the parameterization unusable for application’s purposes. A solution is to partition the surface or introduce cuts in a way which will reduce the distortion. This article presents a new method for cutting seams in 3D mesh surfaces. The addition of seams reduces the surface complexity and hence reduces the metric distortion produced by the parameterization. Seams often introduce additional constraints on the application for which the parameterization is used, hence their length should be minimal. The presented method minimizes the seam length while reducing the parameterization distortion to acceptable level.

Determining reaction abilities of sewing machine operators in joining curved seams

In accordance with his/her psycho‐physical abilities and degree of skill, regulating system in the operator's brain will match the speed of sewing operations, e.g. actual machine stitching speed, using a simple movement of the foot, to adapt it to his/her sensory and motoric reaction abilities. Workpiece in sewing is fed employing three degrees of freedom movement, i.e. using three independent regulating circuits: position of the seam, edges and workpiece layer length. Cybernetic bases of the regulating system man‐machine‐workpiece are presented, as well as the development of the necessary and maximum possible sewing machine operator's reactions in joining curved seams. The procedure is explained by constructing a mathematical model and obtaining the equations used in calculating necessary and maximum operator's reaction abilities. Measurements necessary were performed in the Department of Clothing Technology, Faculty of Textile Technology, University of Zagreb, using modern measuring equipment while garment‐sewing processes were recorded under actual in‐plant conditions. The results obtained were computer‐processed and a 3D graphic representation was obtained together with a mathematical model appropriate to calculate interdependence of the mentioned parameters. Appropriate software package was developed, which allows a quick, accurate and continuous determination of normal machine‐hand times, as dependent on all the influential parameters.

Air channel testing of thermally bonded PVC geomembrane seams

Polyvinyl chloride (PVC) possesses excellent thermal welding characteristics, such as a wide thermal seaming range and the absence of a need for surface preparation such as grinding. The focus of this study was to utilise these welding characteristics to develop a procedure for air channel testing of dual track thermal seams and recommend that destructive testing of PVC geomembranes be reduced and possibly discontinued. This is possible because of the development of a relationship between thermally welded seam burst strength and seam peel strength for a given sheet temperature. To develop this relationship, test welds were created using hot air and wedge welders at two different geomembrane temperatures, two different geomembrane thicknesses, three welding speeds, and three welding temperatures. The 72 seams created were evaluated by conducting ASTM D 6392 peel strength tests at room temperature (22.8°C) and a burst test developed herein at three different sheet temperatures. This paper presents the test results, which illustrate the importance of welding temperature and speed. The test results are also used to develop a relationship between seam peel strength and burst pressure, which can then be used to conduct field burst tests to ensure the specified seam peel strength(s) are satisfied along the entire seam length instead of over the limited seam length used in destructive tests.

Air channel testing of thermally bonded PVC geomembrane seams

Polyvinyl chloride (PVC) possesses excellent thermal welding characteristics, such as a wide thermal seaming range and the absence of a need for surface preparation such as grinding. The focus of this study was to utilise these welding characteristics to develop a procedure for air channel testing of dual track thermal seams and recommend that destructive testing of PVC geomembranes be reduced and possibly discontinued. This is possible because of the development of a relationship between thermally welded seam burst strength and seam peel strength for a given sheet temperature. To develop this relationship, test welds were created using hot air and wedge welders at two different geomembrane temperatures, two different geomembrane thicknesses, three welding speeds, and three welding temperatures. The 72 seams created were evaluated by conducting ASTM D 6392 peel strength tests at room temperature (22.8°C) and a burst test developed herein at three different sheet temperatures. This paper presents the test results, which illustrate the importance of welding temperature and speed. The test results are also used to develop a relationship between seam peel strength and burst pressure, which can then be used to conduct field burst tests to ensure the specified seam peel strength(s) are satisfied along the entire seam length instead of over the limited seam length used in destructive tests.

Phagocytosis by Acanthamoebacastellanii: ionic strength dependence of the probability of cell attachment; ingestion and contact seam morphology

The phagocytosis of glutaraldehyde-fixed horse erythrocytes by Acanthamoeba castellanii has been examined in iso-osmolal phosphate buffered saline/sucrose suspending phases of ionic strength, I, ranging from 0.17 to 0.0017. The erythrocytes were exposed, at a ratio of 15:1, to 5×10 6 amoeba in 0.2 ml volumes. The average number of erythrocytes forming a contact with an amoeba over 30 min ( T 30) was well described by T 30=5.2 exp(−0.112× I −0.5). The index of the exponential ‘probability of attachment’ term may also be expressed in terms of either surface potential ( ψ 0) or the Debye length ( κ −1). The probability term is formally similar to a Bolzmann factor. Electron microscopy showed that contact spreading of the amoeba over the erythrocyte took place by formation of discrete contacts and that the lateral separation distance between contacts was 0.66, 1.36 and 1.59 μm for ionic strengths 0.17, 0.052 and 0.0017, respectively. The direction of change in lateral contact separation distance was consistent with published changes in focal contact separation when amoeba move over glass or when human erythrocyte–erythrocyte adhesion occurs in different ionic strength media. The direction was also consistent with interfacial instability theory predictions for the dependence of localised membrane contact formation on interaction potential. The proportion of attached cells that were subsequently ingested correlated more strongly with the number of contacts formed along the cell–cell contact region (seam) than with the seam length at different ionic strengths.

00/03169 CO 2 sequestration in deep coal seams: Pilot results and worldwide potential

Enhanced recovery of coal bed methane by CO2 injection (CO2-ECBM) offers the potential of increasing recovery of the gas in place relative to primary recovery methods while storing CO2. This paper describes a CO2-ECBM field trial that used a multi-lateral horizontal well with 2.3 km in seam length for injection. The trial, performed in China's Shanxi basin, involved transport of liquid CO2 to the injection site and pumping of this directly into the injection well. A u-tube sampling system was installed in a monitoring well 25 m from the main horizontal branch close to the vertical section of the injection well. This u-tube system comprised three intervals separated by inflatable packers from which gas and water samples were automatically collected and recovered to an on-site field laboratory for gas analysis. The middle interval of this packer assembly was positioned to collect fluid samples from the coal seam targeted for ECBM. At the start and towards the end of the period of CO2 injection, a pulse of non-adsorbing tracer gas was added to the CO2. There was clear breakthrough of the tracer in the middle packer interval of the monitoring well, demonstrating the good connection between the injection and monitoring wells. The CO2 composition of the gas sample from the coal seam gradually increased over time as injected CO2 migrated to the monitoring well and reached a maximum of 12%. Coal permeability, and thus CO2 injectivity, has been observed to decline during other CO2-ECBM field trials as higher adsorbing CO2 displaces reservoir methane. However in this trial there was no clear trend of decreasing injectivity with time, possibly due to the flow behaviour in the long horizontal well and the short periods of CO2 injection.

Influence of some parameters on stitching velocity of sewing

Presents the influence of seam length, normal stitching velocity of a sewing machine and a working method on stitching velocity of sewing. Results show that better stitching velocities of sewing are gained by longer length of seams and higher than normal stitching velocities of a sewing machine. Reveals the working method and type of feeding of material affect the achievement of higher stitching velocities.

Comparison between the lengths of individual osteoid seams and resorption cavities in human iliac crest cancellous bone

The current concept of bone remodelling is based on the belief that bone resorption and formation are coupled both in time and space; this implies that the surface extent of bone eroded in a bone remodelling unit would approximate to the surface extent of the osteoid seam formed subsequently. The greater total surface extent of osteoid as opposed to erosion is generally attributed to the longer life-span of bone formation, but no comparison of the length of eroded surface and osteoid seam within individual bone remodelling units has been reported. In this study we have compared the length of individual osteoid seams, resorption cavities and bone structural units in iliac crest trabecular bone obtained from normal subjects and from patients with renal osteodystrophy. Values for osteoid seam and bone packet length were significantly greater than resorption cavity length in both the normal and patient groups ( P < 0.001), the ratio of osteoid seam and eroded length being similar in the two groups (1:0.44 and 1:0.40, respectively). These results indicate that the discrepancy between total osteoid and eroded surface extent cannot be wholly explained on the basis of a longer formation life-span. Possible additional explanations include underestimation of eroded surface by light microscopic techniques, initiation of bone formation within a cavity before the completion of resorption, the presence of arrested resorption cavities, non-random distribution of resorption cavities on the trabecular surface and bone formation on quiescent bone surfaces.

Analyses and repair of defects found in the primary collector weld seams of the steam generators at loviisa nuclear power station

In conjunction with the final inspection of the Loviisa-2 steam generators, some defects were found in the austenitic weld-seams of the primary collectors. Additional inspections were subsequently performed also on site at Loviisa. Later on, corresponding weld seams in Loviisa-1, which had already been in operation for three years, were inspected. In these radiographic inspections a defect of approximately 80% of the total seam length was found. The inspections were extended to cover all upper and lower austenitic weld seams as well as the bimetallic weld seams of the steam generator collectors. Extensive fatigue and fracture analyses of the welds were performed to estimate the crack growth and the critical crack size. Although the analyses did not demand any repair, it was decided to repair the welds at once as the steam generators were decontaminated. Before the grinding and weld repair, tests were done on full-size test welds to assess repair procedures. Test samples were also cut out from some of the welds to enable metallurgical investigations for finding the reason for and nature of the defects.