Tying Method Research Articles

Consistent mesh tying methods for topologically distinct discretized surfaces in non‐linear solid mechanics

AbstractThis work presents a new technique for joining dissimilar meshes in non‐linear finite element analysis, with the novel result that the adjoining surfaces do not need to be spatially coincident for patch tests to be passed. The work builds in some sense on results previously presented by Dohrmann et al. (International Journal for Numerical Methods in Engineering 1991; 40:1205), but considerably generalizes upon the results presented there. Most importantly, it is shown that consistency of the tied finite element formulation may be achieved such that implementation of element formulations is not affected, through the use of a three‐field variational principle applied over the contacting region. A key conclusion of the work is that although the approach advocated bears some resemblance to mortar element schemes for contact analysis (see, for example, McDevitt and Laursen, International Journal for Numerical Methods in Engineering 2000; 48:1525), a straightforward application of a mortaring scheme is not sufficient to guarantee patch test passage when dissimilar meshing of curved surfaces leads to local open volumes (or overlaps) between tied surfaces in their reference configurations. The proposed algorithm is demonstrated through a number of numerical examples performed within a matrix‐free non‐linear equation solving framework. Published in 2003 by John Wiley & Sons, Ltd.

Laparoscopic intracorporeal square-to-slip knot

We review a laparoscopic, intracorporeal technique of securing the square knot. It is useful when a surgeon’s knot is insufficient to maintain tissue approximation. Advantages include the use of standard tying methods, lack of extracorporeal knot creation or need for a pushing device, and ability to secure the knot in difficult locations.

Distribution-free dispersion tests for data with ties

It is proposed that statistics for comparing dispersion (i.e., spread, scale; e.g., variance) when data are tied should be tie-centered. For statistics which are score sums, this means that if the highest score (indicating the least difference from a center of the data) is assigned to the. median when there are no ties, then the median should have the highest score when there are ties. Using standard methods for ties, most popular dispersion rank test statistics are not tie-centered, e.g., the Ansari- Bradley, Mood and Siegel-Tukey statistics. A new tie-centered rank test statistic with a Wilcoxon distribution is proposed for ordered categorical data. For data consisting of meaningful point values with many ties, the Fligner- Killeen test is proposed. Exact tests and random cut-points tests can be done with these statistics, and cluster sampling can be accommodated.

Laparoscopic suturing evaluation among surgical residents.

Laparoscopic suturing is an integral part of advanced laparoscopic surgery training. The objective of this study was to evaluate the performance and preference of surgical residents performing intracorporeal and extracorporeal knot-tying techniques using conventional and Endo Stitch instruments. The residents were also evaluated on their suturing techniques using conventional instruments, the Endo Stitch, and the Suture Assistant. Using an inanimate laparoscopic trainer model, 39 residents were evaluated as they performed laparoscopic knot tying exercises. Endpoints of the study were execution time and subjective preference of surgical residents with respect to the type of instrument used for knot tying. Forty-three residents were evaluated as they performed laparoscopic suturing exercises with three different types of suturing instruments using the same endpoints. The intracorporeal technique was the preferred (89%) method of knot tying among surgical residents. The time for completion of laparoscopic suturing was significantly (P < 0.05) shorter with the Endo Stitch (114 +/- 64 s) than with the conventional instrument (206 +/- 107 s) or the Suture Assistant (151 +/- 70 s). Residents preferred the use of the Endo Stitch in all three categories for suturing, knot tying, and handling. The Endo Stitch enhanced laparoscopic skills and was the preferred instrument for laparoscopic knot tying and suturing among surgical residents.

Speaker adaptation of acoustic models using correlations of training transfer vectors

The authors proposed for acoustic models based on the hidden Markov model a method that involves applying constraints to the model structure and tying the model's parameters in order to improve the training efficiency. Conventionally, the tied structure of an acoustic model is, mostly, defined by tying several adjacent parameters and expressing them with a single representative parameter. This method can be regarded as a tying method based on the parameters' values, under the assumption that adjacent parameters, usually, exhibit similar behavior. As opposed to this concept, the current study proposes a tied structure with consideration of transfer (movement) of parameters. A large volume of training data was used to measure transfer of each parameter during training, and tying relationships regarding the transfer vectors were organized between parameters performing statistically similar movements. In particular, in the current study, the authors concentrated on mean vectors of fundamental distributions and followed movements of these mean vectors during training of initial models (speaker-independent models) by acoustic data from different speakers. The structure was defined by identifying the mean vectors characterized by strong correlation of movements during training, and tying their corresponding transfer vectors. Speaker adaptation tests confirmed high training efficiency of the model obtained as a result of this tying. © 2000 Scripta Technica, Syst Comp Jpn, 31(14): 74–82, 2000

Friction in perspective

In the past, most frictional resistance studies have been conducted in a steady state condition that does not simulate the dynamics of the oral environment. Various oral functions as chewing, swallowing, speaking, etc, as well as the oral tissues contacting any orthodontic appliances, result in periodic, repetitive, minute relative motion at the bracket/arch wire interfaces several thousand times each day. This in turn affects the normal forces at the interfaces, and because frictional resistance is directly proportional to the normal force, a pilot study was undertaken to emulate the dynamic environment of the oral cavity and its effect on frictional resistance. Tests of a limited sample of stainless steel arch wires and brackets typically used in sliding mechanics revealed that frictional resistance was effectively reduced to zero each time minute relative movements occurred at the bracket/arch wire interfaces. Factors such as the degree of dental tipping, relative arch wire/slot clearances, and method of tying, did not have a measurable effect on frictional resistance in the simulated dynamics of the oral environment. (Am J Orthod Dentofacial Orthop 1999;115:619-27)

New Effective Potentials Extraction Method for the Interaction between Cations and Water

A very simple method for the extraction of effective interaction potentials from ab initio calculations was proposed (Periole et al. J. Phys. Chem. 1997, 101, 5018), and simple two-body cation−water interaction potentials were derived for several cations, Li+, Na+, K+, Be2+, Mg2+, and Ca2+, using two facts: first, water molecules in the close vicinity of cations are strongly structured and present a constrained orientation towards the ion; second, at larger distances the ion-water interaction is mainly electrostatic. In the present work, an extension to Rb+ and Sr2+ and some refinements of this method are presented. In particular, we explore the most adequate way of including the nonadditivity and polarization effects that arise from the ion-water-water and water-water interactions. The potentials obtained with the new extraction methods are compared with the empirical potentials of Åqvist (Åqvist, J. J. Phys. Chem. 1990, 94, 8021) that were adjusted to reproduce experimental data. Those obtained with the exploration−TIE method are also tested by performing molecular dynamics simulations of the various cation−water systems and the results are found to be in good agreement with experimental data. In particular, they yield cation hydration free energy differences (ΔG values) that are, in general, in good accordance with experimental figures. This latter method is ideally suited and easy to apply to obtain effective interaction potentials for molecular systems with restricted geometric conditions that appear in numerical simulations, either Monte Carlo or molecular dynamics.

Laparoscopic suturing and knot tying: the Indian rope trick.

Laparoscopic suturing and knot tying require a lot of patience and practice and can be difficult, time consuming, and frustrating in spite of the advances made in the fields of instrumentation, optics, and imaging. The new technique described here is an effort to make the procedure simpler by providing extracorporeal control of one limb of the suture. It involves percutaneous placement of the needle end of the suture in the abdomen and its removal using a modified 10 cm long cloth-sewing needle. The part of the suture hanging from the abdominal wall helps in the formation and the tying of both the extracorporeal and the intracorporeal knots. The extracorporeal knot is just pulled in percutaneously to make it intracorporeal and can be tightened easily without a knot pusher. The loop for making the intracorporeal knot is formed in one of three ways, and the half hitch or the surgeon's knot can be tightened by pulling one end extracorporeally and the other intracorporeally. The technique has now been used for 36 laparoscopic procedures (8 transperitoneal and 28 retroperitoneal), including cholestectomy, varicocelectomy, ureterolithotomy, pyelolithotomy, pyeloplasty, and nephropexy. Compared with the conventional method of laparoscopic suturing and knot tying, it was found to be easier to learn.

A new direction in laparoscopic suturing and knot tying

An intracorporeal knot can be tied using instruments, employing a method that mimics the actions of the hooked index finger as used in the one‐handed, hand tie, of open surgery. The short end of the suture, when held in the instrument jaws, can be looped around the bite section of the suture. This rotation is facilitated by a spiral spur member, which is affixed to the instrument jaw, and which captures the bite. For maximum efficiency one uses paired left and right instruments, where the spiral spurs are directed clockwise and anticlockwise, respectively. Instrument rotation and minimal instrument transfers are required for this technique. The surgical half‐hitch can be created by two entirely different actions, the instrument‐ or the hand‐tied method. Each of these methods could be considered to be the converse of the other. Ergonomically designed instruments are essential for laparoscopic surgery. A role for instrument axial rotation is recognized and extended in this new method of laparoscopic knot tying. This novel technique contrasts with all known knotting methods.

A new device and method for extracorporeal knot tying in laparoscopic surgery.

Advances in laparoscopic suturing will be facilitated by the ability to tie knots rapidly and effectively. A new device is presented that enhances extracorporeal laparoscopic knot tying, using familiar surgeon's or square knots in any size or type of suture material. It speeds knot formation and allows precise control of knot placement in a wide variety of applications.

Calculation of stress intensity factors of surface cracks in complex structures: Application of efficient computer program EPAS-J1

A finite element computer program EPAS-J1 was developed to calculate the stress intensity factors of three-dimensional cracks. In this program, the stress intensity factor is determined by the virtual crack extension method together with the distorted elements allocated along the crack front. The program also includes the connection elements based on the Lagrange multiplier concept to connect such different kinds of elements as the solid and shell elements, or the shell and beam elements. For the structure including the three-dimensional surface cracks, the solid elements are employed only at the neighborhood of the surface crack, while the remainder of the structure is modeled by the shell or beam elements since the crack singularity is very local. Computer storage and computational time can be highly reduced with the application of the above modeling for calculation of the stress intensity factors of the three-dimensional surface cracks, because the three-dimensional solid elements are required only around the crack front. Several numerical analyses were performed by the EPAS-J1 program. At first, the accuracies of the connection element and the virtual crack extension method were confirmed using the simple structures. Compared with other techniques of connecting different kinds of elements such as the tying method or the method using an anisotropic plate element, it is found that the present connection element provides better results than the others. It is also found that the virtual crack extension method provided the accurate stress intensity factor. Furthermore, the results are also presented for the stress intensity factor analyses of cylinders with longitudinal or circumferential surface cracks using the combination of various kinds of elements together with the connection elements.

Additional Techniques and Safety Hints for Climbing Tall Trees, and Some Equipment and Information Sources

This paper comments on tree-climbing methods presented by Perry (1978) and gives alternative techniques, safety hints, and sources for more information and equipment used in rope and descending. DONALD PERRY'S (1978) PAPER describing a method for climbing tall rain forest trees is welcome in that it introduces tropical biologists to specialized techniques known mostly to cavers and rockclimbers. A potential hazard exists, however, if persons lacking experience with such techniques are to learn them from Perry's paper and then apply them without further guidance. The purpose of this paper is to point out one specific lapse of safety precautions in Perry's paper, to give several tips on the safe use of rope-ascending techniques, and to point out a few reliable sources of equipment and information on such techniques. The techniques described here have been used by the author during 10 years of vertical caving and rockclimbing, and in two seasons of climbing tropical forest trees in the course of a study of the bat falcon (Falco rufigalaris). Figure 1 of Perry's paper shows non-locking carabiners (steel or aluminum snap-links) linking the jumars (mechanical ascenders) to the slings which support the climber. This practice should never be permitted, as non-locking carabiners can be accidentally opened by contact with rope, limbs, etc., resulting in a fall. Furthermore, the use of evenlocking carabiners should be avoided whenever it is possible to eliminate them by affixing slings directly to the ascenders by means of a girth hitch (fig. 2d) or other suitable knot. The philosophy of anyone using climbing equipment should be to minimize the number of links in the system, since each link is a potential site for equipment or operator failure. As a rule, any carabiner linking the climber to his/her or rappeling gear should be of the locking variety. Steel-locking carabiners are preferable to aluminum ones for this application, as the latter may experience damage to threads as a result of the harness sling hanging up on the collar of the locking mechanism. This problem can also be elimi1Present address: Department of Zoology, University of California, Davis, California 95616, U.S.A. nated by attaching the sling to the carabiner by means of a girth hitch (fig. 2d) which prevents back-and-forth movement of the sling which can result in the hanging-up referred to. If locking carabiners are not available, two regular carabiners should be used in combination, with the gates on opposite sides. Another important safeguard is to have more than one ascender linked to the climber's harness so that the failure of one ascender or sling will not result in a fall. This may be achieved in Perry's system by adding a loop of webbing or rope connecting the lower (feet) jumar to the parachute harness. This loop should be long enough to be slack during normal operations but will prevent a fall should the upper ascender or its sling fail. While this type of ascender has been known to disengage inadvertently from the climbing rope, primarily when the climber is ascending along a horizontal or diagonal rope, it is, nonetheless, probably the safest and most versatile mechanical ascender available and is enjoyable to use with the proper precautions. Though a person may prefer to use mechanical ascenders such as the jumars pictured by Perry, anyone using such ascenders should also be aware of the method for tying and using prusik knots. These knots can be made of manila, nylon, or polypropylene ropes which are relatively cheap and available in the most remote villages. Thus, this system has the advantages of economy and utility in unanticipated ascents or emergencies. If frequently inspected for wear and replaced judiciously, prusik knots are probably safer than mechanical ascenders; many cavers use them as their sole means of ascent. Prusik knots work as slip-knots; they can be moved up or down the rope after a quick loosening motion, but catch and hold when weight is applied. Though some systems employ only two knots, the three-knot system is inherently safer as it provides an additional 286 BIOTROPICA 13(4): 286-291 1981 This content downloaded from 157.55.39.153 on Mon, 19 Sep 2016 04:39:18 UTC All use subject to http://about.jstor.org/terms

Grapevine Propagation. VI. Variations on Standard Field Budding

Rootstocks budded with refrigerated budwood in the fall and tied with rubber budding strips gave a higher take than those tied with plastic tape. Rootstocks budded with fresh budwood in the fall had equally successful takes regardless of method of tying. Budded vines tied with plastic tape and decapitated early gave an earlier bud push and shoot growth.

Activity Measurements of the Binary Mn-Base Molten Alloys by the TIE Method

Activity Measurements of the Binary Mn-Base Molten Alloys by the TIE Method

A New Continuous-string Method of Plant Tying in Greenhouses1

Abstract A new method for supporting plants in a greenhouse reduces labor time for such training by 66%. The method utilizes a continuous string tied to overhead hooks and looped around the base of the plants by a tube held by an operator who stands on the ground.

Measurements of Activities of Silver in Silver-Bismuth Molten Alloys by the TIE Method

Measurements of Activities of Silver in Silver-Bismuth Molten Alloys by the TIE Method

Activity Measurements of the PbO&amp;ndash;SiO&lt;SUB&gt;2&lt;/SUB&gt; Melts by the TIE Method

Activity Measurements of the PbO&amp;ndash;SiO&lt;SUB&gt;2&lt;/SUB&gt; Melts by the TIE Method

Comparison of several methods of blanching cauliflower curds on labor requirement and yield and quality of curds

This investigation was made to seek for the efficient methods of blanching cauliflower curds, comparing several methods on labor reauirement and yield and quality of curds.Labor requirement of blanching curds was the lowest by breaking two outer leaves and folding them over the curds and was the highest by tying the wrapper leaves together at the top with rice straws or polyethylene tapes. Tying by rubber bands was medium in efficiency.Size of the curds by methods of broken leaves was distinctly larger than that by tying methods. Breaking two outer leaves had not practically any effect on the size of curds, compared with the curds of intact plants.Whiteness of curds was significantly affected by methods of blanching. Proportion of pure white curds was much higher on blanching by broken leaves than on blanching by tying.Thus blanching by broken leaves was shown to excel other tying methods in labor efficiency and yield and quality of curds harvested.

Measurements of Activities of Sulfur in the Bismuth-Sulfur Melts by the TIE Method

Measurements of Activities of Sulfur in the Bismuth-Sulfur Melts by the TIE Method

Activity Measurements of Binary Pb&amp;ndash;X Molten Alloys by the TIE Method

Activity Measurements of Binary Pb&amp;ndash;X Molten Alloys by the TIE Method