Oval Holes Research Articles

Stress analysis of an elastic plate with an opening or notches under tension based on the concept of general systems

The paper presents a method of calculation dealing with plane stress problems, based on the concept of general systems theory. The first part makes a proposal for calculating the stresses and the stress concentration factor of an elastic plate with a circular hole under tension. The remainder describes its application to similar problems, such as an elastic plate with an elliptical hole, an oval hole and semi-circular notches under tension. The stresses at any point in a plate are calculated from the effect of the stresses on the boundaries. General systems theory suggests state object evolves at discrete times. The deformation of the plate is supposed to take a few steps along the time axis, though the real deformation finishes at one step. The results were compared with analytical solutions and/or experimental results.

Anatomie fonctionnelle du nerf trijumeau

The cranial nerve (CN) V is a mixed nerve that consists primarily of sensory neurons. It exits the brain on the lateral surface of the pons, entering the trigeminal ganglion within a few millimeters. Three major branches emerge from the trigeminal ganglion. The first division (V1, the ophthalmic nerve) exits the cranium through the superior orbital fissure, entering the orbit to innervate the globe and skin in the area above the eye and forehead. The second division (V2, the maxillary nerve) exits through a round hole, the foramen rotundum, into a space posterior to the orbit, the pterygopalatine fossa. It then re-enters a canal running inferior to the orbit, the infraorbital canal, and exits through a small hole, the infraorbital foramen, to innervate the skin below the eye and above the mouth. The third division (V3, the mandibular nerve) exits the cranium through an oval hole, the foramen ovale. The third division also has an additional motor component, which may run in a separate fascial compartment. Most fibers travel directly to their target tissues. Sensory axons innervate skin on the lateral side of the head, the tongue, and the mucosal wall of the oral cavity. Motor fibers innervate the muscles that are attached to the mandible. Some sensory axons enter in the mandible to innervate the teeth and emerge from the mental foramen to innervate the skin of the lower jaw.

Ultrathin self-assembled fibrin sheets

Fibrin polymerizes into the fibrous network that is the major structural component of blood clots and thrombi. We demonstrate that fibrin from three different species can also spontaneously polymerize into extensive, molecularly thin, 2D sheets. Sheet assembly occurs in physiologic buffers on both hydrophobic and hydrophilic surfaces, but is routinely observed only when polymerized using very low concentrations of fibrinogen and thrombin. Sheets may have been missed in previous studies because they may be very short-lived at higher concentrations of fibrinogen and thrombin, and their thinness makes them very difficult to detect. We were able to distinguish fluorescently labeled fibrin sheets by polymerizing fibrin onto micro-patterned structured surfaces that suspended polymers 10 microm above and parallel to the cover-glass surface. We used a combined fluorescence/atomic force microscope system to determine that sheets were approximately 5 nm thick, flat, elastic and mechanically continuous. Video microscopy of assembling sheets showed that they could polymerize across 25-microm channels at hundreds of microm(2)/sec (approximately 10(13) subunits/s x M), an apparent rate constant many times greater than those of other protein polymers. Structural transitions from sheets to fibers were observed by fluorescence, transmission, and scanning electron microscopy. Sheets appeared to fold and roll up into larger fibers, and also to develop oval holes to form fiber networks that were "pre-attached" to the substrate and other fibers. We propose a model of fiber formation from sheets and compare it with current models of end-wise polymerization from protofibrils. Sheets could be an unanticipated factor in clot formation and adhesion in vivo, and are a unique material in their own right.

Treatment of femoral and tibial diaphyseal nonunions using reamed intramedullary nailing without bone graft

Intramedullary nailing has long been used successfully in the treatment of aseptic nonunions of the femur and tibia. However, recently the efficacy of reamed intramedullary nailing in the treatment of nonunions of the femur has been questioned by some publications reporting unfavourable results. The purpose of this study is to evaluate the treatment results of femoral and tibial diaphyseal nonunions with intramedullary nailing. We retrospectively reviewed thirty-two patients with femoral or tibial diaphyseal nonunions who were treated with reamed intramedullary nailing between May 2002 and April 2006. Fixation status at the time of treatment were nail in twenty-eight patients (12 femurs, 16 tibiae), plate in three cases (2 femurs, 1 tibia), no implant in one femur. We used a dynamically locked, reamed intramedullary nailing. Only in bone defects greater than 50% of the cortical diameter and more than 2 cm in length was open bone grafting performed. Solid union was achieved in 93% (fourteen of fifteen) of femoral nonunions and 94% (sixteen of seventeen) of tibial nonunions. Our protocol with a dynamically locked, reamed nailing with the use of an oval hole and no open bone grafting for a defect less than 50% of the diameter and immediate weight bearing was successful in the treatment of femoral and tibial diaphyseal nonunions.

Mud Design To Prevent Circulation Losses

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 105449, "Design of Well Barriers To Combat Circulation Losses," by Bernt S. Aadnoy, SPE, Mesfin Belayneh, SPE, and Miguel Arriado, U. of Stavanger, and Roar Flateboe, BP plc, prepared for the 2007 SPE/IADC Drilling Conference, Amsterdam, 20–22 February. The full-length paper summarizes a 10-year research program in borehole fracturing and mud design. Numerous experiments were conducted with oil- and water-based drilling fluids to understand better the mechanisms that lead to circulation losses. A new mechanistic model for fracturing is presented that is different from other recent models, and the model was verified with laboratory experiments. The model defines optimal barrier filtrate loss to place particles in the loss zone. Selected laboratory experiments are presented that demonstrate that borehole fracturing resistance can be improved significantly by changing mud composition. Introduction Recognizing that borehole-stability mechanisms are not understood fully, research carried out during the past 10 years has focused on the fundamental physics and chemistry. Fig. 1 shows a fracturing cell where specially prepared hollow concrete cores are fractured. The setup also allows for mud circulation to ensure that mud particles are well distributed inside the hole. The cell is rated to 69 MPa, and the axial load, confining pressure, and borehole pressure can be varied independently. Many oil- and water-based drilling fluids were tested as well as novel ideas such as changing rock wettability or creating other chemical barriers. Cores with circular, oval, and triangular holes were tested to study effects of hole geometry. Fig. 2 shows typical results from the fracturing experiments. The commonly used Kirsch equation defines the theoretical fracture pressure in a nonpenetrating situation such as when using drilling muds. Only one of the three measured fracture pressures agrees with the theoretical model, and the other two are much larger. Several conclusions came out of this research.The theoretical Kirsch model underestimates the fracture pressure in general.There is significant variation in fracture pressure, depending on mud quality. This shows that the fracture pressure can be increased by designing a better mud. Several devices were constructed to study the mud and its filter cake. Fig. 3 shows a mud cell with six outlets to simulate fractures of various dimensions. The mud is circulated with a low-pressure pump to develop a filter cake across the slots. Then, a high-pressure pump increases the pressure until the mudcake breaks down. In this way, the stability and strength of the mudcake can be studied. Common muds and additives were used, and the observation was made that reducing the number of additives often results in a better mud. Nonpetroleum products also were studied to look for improvements.

Fitting Oval Pegs Into Round Holes

A study of qualitative researchers who have submitted and/or published their research in top-tier North American organizational and management journals reveals the evaluative criteria-in-use at these journals. Specifically, when asked to take the perspective of an (a) author, (b) evaluator (reviewer or editor), and (c) judge of the comparisons between qualitative and quantitative research, three publication tensions were evident. The author offers the metaphor of ``fitting a round peg into an oval hole'' as a means of capturing these tensions and as a vehicle for organizing the various ways these tensions can be managed.

Effect of material properties on deformation behavior in incremental tube-burring process using a bar tool

To enhance the formability, product quality and process flexibility of large branched tubing, a new incremental burring process for manufacturing branched tubing without welding has been developed. A highly significant processing path using a bar tool is proposed that is based on the forming characteristics of two conventional forming processes, namely, the rigid plug pullout method and the T-drill method. In this paper, a suitable tooling path and the effect of the tubular material properties on the incremental tube-burring process to achieve a more uniform thickness distribution at the edge of branched tubing has been investigated using a simulation. In the analysis, the tubular material used for branched tubing was the aluminum alloy, A5083-O, with a diameter of 400 mm and wall thickness of 6.0 mm, while an oval hole in the mother tube had a major axis of 360 mm and a minor axis of 194 mm. A bar tool with a diameter of 65 mm was used for the incremental tube-burring method. This burring model was analyzed using an explicit finite element method code. This method consists of three processes: (i) the oval hole is expanded by moving a bar tool keeping vertical tool condition nearby minor axis area, (ii) the oval hole is deformed and flanged-up at major axis by rocking and raising a bar tool, (iii) the oval hole is expanded out and flanged-up to the desired diameter of the branched tubing. The thickness reduction ratio distribution at the edge of branched tubing is influenced by material properties such as the n -value, the transverse anisotropy, and the planar anisotropy. The validity of this simulation model was also verified by comparing with experimental results.

Accuracy Improvement in Injection Molding Using Milling-Combined Laser Metal Sintered Mold

Effective cooling channels have been installed in the injection mold during the process of milling-combined laser metal sintering. In the case of molding a flat piece with multiple ribs, it is difficult to insert cooling channels between the ribs by conventional machining. Because the heat remains between the ribs, the piece shrinks after the molding to form a warp on the flat surface. Using milling-combined laser metal sintering, oval holes were fabricated between the ribs and they were connected in a spiral loop. The temperature around the ribs became uniform and the warp on the flat surface of the molded specimen reduced compared with that molded in the mold made by conventional method using milling and electro-discharge machining. Simulation of the mold temperature and the warp by commercial software showed the same tendency on the change of the warp with the mold type and the cooling temperature conditions. Therefore, the accuracy of the molded specimen is improved by inserting cooling channels in the mold where heat accumulates using a milling-combined laser metal sintering and the effect can be evaluated by a simulation.

Parasitization of aphids on cauliflower seed crop in relation to their population build-up in mid-hills of Himachal Pradesh.

Continuous monitoring of aphid population on cauliflower seed crop from December to April revealed an increase in infested plants (23 to 48%). aphid population (8 to 131/plant) and parasitization (I to 3.8%) during January to mid-March, followed by a decline in aphid infestation and further increase in parasitization (to 7.4%) till April 6, despite prominence of coccinellid activity (0.8-9.5 beetles/plant). There was concomitant occurrence of Brevicoryne brassicae (Linnaeus) and Myzus persica (Sulzer), the former being predominant (65.3%) and their parasitization varied from 0.7-8.3 (av. 3.6 and 8-8.2 per cent (av. 4.4). respectively. Intra-plant distribution indicated that aphid infestation was maximum on inner whorl of leaves. followed by middle and outcr whorls. but number of mummified aphids did not vary significantly in respect of position of leaves. During mid-March to early-April also, H. brassicae outnumbered M. persicae on terminal bolts and thcil' parasitizlltion was 27.4 and 14.5 per cent. From the mummies of aphids collected from the cabbage fields during Decemher. and May-June, the arasitoid Diaeretiella rapae (M'Intosh) (Aphidiidae) and thc hypeqlanlsitoid Pachyneuron aphids (Bouche) (Pteromalidae) emerged. but the emergence was poor (5.6 and 6.3% respectively), The mummics from which the parasitoid emerged were bigger with oval and uniform emergence holes around cornicles than the mummies from which hyperparasitoid emerged, The emergence holes or the lattel was irregular, smaller and often towards anterior side of the body,

Ambesh???s T-Dagger??: A New Device for Quick Bedside Percutaneous Dilational Tracheostomy

To the Editor: Since the rejuvenation of interest in the percutaneous dilational tracheostomy in 1985, a number of percutaneous dilational tracheostomy kits have been made available. The commonly used percutaneous dilational tracheostomy kits are Ciaglia’s serial dilators, Griggs guidewire dilating forceps, Ciaglia Blue Rhino, and Frova’s PercTwist (1–4). Each kit has several advantages and disadvantages. Further efforts are underway to develop a percutaneous tracheostomy kit that is easy to operate and has minimal potential complications. Recently, Ambesh’s T-Dagger, a new percutaneous dilational tracheostomy device (patent pending), has been introduced. It is here described in brief. Ambesh’s T-Dagger is a T-shaped, semi-rigid device made up of polyvinyl chloride (Fig. 1). The shaft of Ambesh’s T-Dagger is smoothly curved at approximately a 30° angle, is elliptical in cross-section; it has a number of oval holes. These holes are meant to provide to-and-fro airflow during ventilation when the shaft lies inside the tracheal lumen during stoma formation. The elliptical shape of the T-Dagger should provide sufficient room for ventilation without air trapping and the passage of fiberoptic bronchoscope into the trachea. The tapered sides of the Ambesh’s T-Dagger shaft should reduce the difficulty in its insertion during tracheal stoma formation. The distal end of the T-Dagger is incorporated with a 5-cm long Teflon guide catheter and the proximal end has two shoulders for a better grip. A J-tip guidewire can be passed through a tunnel of the shaft and the guide catheter to facilitate tracheal stoma formation over it. The inherent design of the device should form adequate size of tracheal stoma for respective sizes of tracheostomy tube and overdilation of tracheal stoma is not possible. Ambesh’s T-Dagger is available in two sizes for 7-mm and 7.5-mm and 8-mm and 8.5-mm tracheostomy tube sizes. Economically, it is much cheaper than the Ciaglia’s Blue Rhino.Figure 1.: Percutaneous tracheostomy kit with Ambesh’s T-Dagger.The steps of forming the percutaneous dilational tracheostomy with Ambesh’s T-Dagger are essentially the same as with the Ciaglia’s Blue Rhino except that the introduction of a separate guide catheter is not required. After a 1-cm transverse skin incision at the intended tracheostomy site, the trachea is punctured with the cannula on the needle and the J-tip guidewire is inserted. A small tracheal stoma is formed with a 14-gauge initial dilator. Ambesh’s T-Dagger is now loaded over the guidewire and advanced, preferably with both the hands holding its shoulder, until its proximal mark lies inside the tracheal lumen. The Ambesh’s T-Dagger is then removed, leaving the guidewire in situ. An appropriately sized tracheostomy tube with its obturator can be introduced over the guidewire. The obturator and guidewire is removed, the tracheal cuff is inflated, and air entry into lungs is confirmed on ventilation. As with other percutaneous dilational tracheostomy techniques, fiberoptic bronchoscopic assistance is advisable. Sushil P. Ambesh, MD Chandra K. Pandey, MD Department of Anesthesiology Sanjay Gandhi Post Graduate Institute of Medical Sciences Lucknow, India [email protected]

Can the Proximal Femoral Nail be Improved?

The Proximal Femoral Nail® (PFN) has an extra hip pin in the head–neck fragment, to prevent rotation of the fracture fragments. However, this hip pin brought along two unexpected complications: medial migration and cutout. In order to reduce the risk of migration and cutout, the hip pin should bear no or minimal load. For this reason, a modified PFN (mPFN) prototype was developed, with an oval instead of a round hole in the nail through which the hip pin passes. Under load–bearing conditions the hip pin could angulate, thereby reducing its load, but maintaining its antirotational function. A multicenter observational study was initiated, to investigate the handling of the mPFN, the stability and strength of the construct, the incidence and type of implant–related complications, and whether the angulating hip pin concept functioned in clinical practice. In six European teaching hospitals 250 patients with unstable trochanteric fractures were included and treated with the mPFN prototype. Handling was found to be equal to the use of the regular PFN. No breakage of the nail at the side of the oval hole was documented. The cutout risk was practically, but not completely, eliminated, if reduction of the fracture and position of fixation were adequate. Medial migration was no longer documented. The angulation concept with the oval hole in the intramedullary nail of the mPFN worked in clinical practice, and helped further reducing the risk of specific implant–related complications.

Modeling of viscous damping of perforated planar microstructures. Applications in acoustics

The paper contains an analysis of the viscous damping in perforated planar microstructures that often serve as backplates or protecting surfaces in capacitive microsensors. The focus of this work is on planar surfaces containing an offset system of periodic oval holes or its limit cases: a system of circular holes or of slits. The viscous damping is calculated as the sum of squeeze film and the holes' resistances. The optimum number of holes is determined which minimizes the total viscous damping for a given percentage of open area. Graphs and formulas are provided for designing these devices. In the case the open area is higher than 15% the numerical results show that the influence of the holes' geometry (circular or oval) has a slight influence on viscous damping. As the planar structures containing oval holes assure a better protection against dust particles and water drops, they should be preferred in designing protective surfaces for microphones working in a natural environment. The obtained results also can be applied in designing other MEMS devices that use capacitive sensing such as accelerometers, micromechanical switches, resonators, and tunable microoptical interferometers.

Initial predation and parasitism by muricid whelks demonstrated by the correspondence between drilled holes and their apparent enveloper

The morphologies of drilled holes enveloped by three coexisting muricid whelks, Morula musiva, Cronia margariticola and Ergalatax contractus, were compared. The results were used to demonstrate the replacement of feeders using drilled holes, and to estimate the frequency of this occurrence in the field. In the laboratory, M. musiva made circular internal holes, whereas C. margariticola and E. contractus made oval holes, when they preyed upon the mussel Hormomya mutabilis. The maximum inner diameter of the hole correlated with the driller's shell height in all three muricid species. In the field, mussels enveloped by M. musiva had circular drilled holes, as was found in the laboratory, and the correlation between maximum diameter and enveloper's shell height was not significantly different from that found in the laboratory. In contrast, holes enveloped by C. margariticola in the field were more circular than those observed in the laboratory, and there was no correlation between maximum diameter and enveloper's shell height. Statistical analyses of these results indicated that more than half of the mussels being ingested by C. margariticola had been drilled by M. musiva, i.e. C. margariticola would often kleptoparasitize or scavenge M. musiva's prey by taking over the drilled hole. Few M. musiva would take over the holes drilled by C. margariticola or E. contractus. Furthermore, probably few M. musiva would take over the hole made by a conspecific initial drilling predator. It appears that E. contractus rarely initiates predation by drilling.

A novel locus for parietal foramina maps to chromosome 4q21-q23.

Parietal foramina [PFM], inherited usually in an autosomal dominant mode, is an extremely rare developmental defect characterized by a symmetrical, oval hole in the parietal bone. It can be present as either an isolated or a syndromic feature. PFM types 1 and 2 (PFM1 and PFM2) have been found to be caused by mutations in the MSX2 and ALX4 genes, located to chromosomes 5 and 11, respectively. After exclusion of both the above loci in a large Chinese pedigree with autosomal dominant PFM, a genome-wide search revealed a linkage of the PFM to markers at the 4q21-q23 region. The maximum LOD score from two-point linkage analysis is 3.87 for marker D4S2961. Analysis of co-segregated haplotype localized the region to a 20-cM interval that flanks D4S392 and D4S2945. Therefore, we concluded that the PFM in the family is a new PFM locus. Although three genes, BMPR1B, PP1 and IBSP, are located to 4q21-q25 and their functions are related to bone morphogenesis, no mutations were identified by sequencing analysis of their exons.

The Treatment of Distal Metaphyseal Fractures of the Tibia with a New Nailing System: Technical Advantages and Pitfalls

Aims: Distal metaphyseal fractures of the tibia are relatively frequent and form a separate group of lesions, because of difficulties with reduction and fixation of the distal fragment. As a consequence, most fixation techniques yield unsatisfactory results. We want to describe our experience with a new nailing system, putting emphasis on technical advantages and pitfalls. Methods: Eight patients with distal metaphyseal fractures of the tibia were treated with the TriGen nailing system (Smith & Nephew, Memphis, TN, USA). The mean age of our patients was 50 years (range: 24 to 77 years). Of these 8 patients, 2 sustained an open fracture (Gustillo III a and III b). Reamed and unreamed techniques were used in 7 patients and 1 patient, respectively. No uniform strategy was adopted for distal locking. Results: Technically, the particular design of this nailing system resulted in an unexpected advantage. The oval dynamic screw hole at the distal end of the nail helped to reduce varus malalignment of distal tibia in several fractures.Both open fractures resulted in a non-union. In the first, only one screw was used for distal locking. The other was treated unreamed and the two distal screws were positioned in the frontal plane (parallel placement). The 6 closed fractures went on to uneventful healing within 3 months after injury. Two cases had a decreased mobility of the ankle joint. Conclusion: For the treatment of distal metaphyseal fractures of the tibia, the particular design of the nail we used (oval hole at the tip of the nail) provides a possible technical advantage, which is helpful to reduce varus malalignment of the distal tibia. Based on our clinical experience we recommend systematic reaming, as well as using at least two crossed screws for distal locking, in order to enhance stability.

Characteristics of various film cooling jets injected in a conduit.

In the present study, film cooling characteristics by the jets through various easy-to-make straight holes and slots have been investigated. In this experiment, seven kinds of injection geometries were used. They were circular, rectangular, elliptic and oval holes and slots, respectively.

Approximate Method for Calculating the Interference Effect of Stress Concentration between a Notch and a Crack.

In this study, the problems of interference between an oval hole and a crack in an infinite plate subjected to tension were treated. The method of analysis is an approximate method based on the principle of superposition. In this method, the effect of a small crack existing near an oval hole was treated as the effect of internal pressure expressed by a quadratic expression. The interference effects were calculated by using the present method. The coefficient of the quadratic expression were determined through the interference effects between an oval hole and a crack. KI and KII values calculated by the present method were sufficiently accurate in the practical use.

Layer Manufacturing of Heat Exchange Elements using Photochemical Machining, Electroplating and Diffusion Brazing

SUMMARYA number of heat exchanger elements for a Stirling engine were designed but found to be very difficult to manufacture using conventional technology. Each element required 1800 <lmm oval holes through a 70 mm length of the cooler. The elements were produced by repeated photochemical machining of 185 copper sheets of 0.455 mm thickness. These were electroplated with tin and joined using a process known as diffusion brazing. This paper describes the science and process of manufacturing these components. The procedure was complicated by the need to integrate spigots at each end of the cooler, which meant that some layers required selective diffusion soldering.

Residual stresses in welding circular and oval holes

Residual stresses in welding circular and oval holes

An anatomic study of the effects of dural puncture with different spinal needles.

The purpose of this study is to evaluate the effects of puncture of lumbar dura mater with needles of different sizes and with bevels of different shapes. After removal, the dura was punctured with different needles (22-, 25-, 27-, and 29-gauge Quincke, 24-gauge Sprotte, 22-gauge Whitacre, and 18-gauge Tuohy needles) and observed by stereomicroscope to examine the gross morphology. Histologic features were observed by light microscope using frozen and fixed samples stained with hematoxylin and eosin or specific methods (Masson and Weigert) to evidence elastic or collagen fibers. Puncture hole size was proportional to the size of the needle used. Quincke type needles determined oval or ellipsoidal holes; pencil-point needles determined more rounded holes. Dural retraction determined a reduction of the holes in all cases. Histologic examination revealed an irregular border of the hole, with sectioned as well as compressed fibers. The pattern of compressed but not sectioned fibers was observed more frequently in the samples punctured by pencil-point needles. This study confirms that the arrangement of dural fibers is not as uniform as previously thought. Histologic findings confirm the current opinion that pencil-point needles may be less traumatic than Quincke-type needles. The direction of the bevel of the needle does not appear to have great importance in determining the shape of the hole.