Bow Angle Research Articles

Surgical tips of intramedullary nailing in severely bowed femurs in atypical femur fractures: Simulation with 3D printed model

IntroductionThe surgical management of atypical femoral fractures (AFFs) is complex in cases with severe bowing of the femur, being associated with a high rate of failure. Our first aim was to use preoperative templating and 3D printed model characterise the technical difficulties associated with use of current commercially available intramedullary nail (IMN) systems for the management of AFFs with severe bowing. Our second aim was to use outcomes of our 3D printing analysis to define technical criteria to overcome these problems. Material and MethodsThe modelled femur with 3D printing had an anterior bowing curvature radius of 772mm and an angle of lateral bowing of 15.4°. Nine commercially available IMN systems were evaluated in terms of position of the nail within the medullary canal, occurrence of perforation of femoral cortex by the distal tip of the nail, and location of the site of perforation relative to the knee joint. The following IMN systems were evaluated: unreamed femoral nail (UFN), cannulated femoral nail (CFN), Sirus nail, right and left expert Asian femoral nail (A2FN), right and left Zimmer Natural Nail (ZNN), proximal femoral nail anti-rotation (PFNA), and Zimmer Cephalomedullary Nail (CMN). ResultsAlong the sagittal plane, the UFN, CFN and Sirus systems were acceptably contained within the medullary canal, as well as the “opposite side” A2FN and ZNN. Only the Sirus IMN system was contained along the coronal plane. The distal part of the all other IMN systems perforated the anterior cortex of the femur, at distances ranging between 2.8 and 11.7cm above the distal end of the femoral condyles. Using simulated fracture reduction in the 3D printed model, none of the 9 IMN systems provided acceptable anatomical reduction of the fracture. A residual gap in fragment position and translation was provided by the “opposite side” ZNN, followed by the UFN and Sirus systems. ConclusionCommercially available IMN systems showed mismatch with severely bowed femurs. Our simulation supports that fit of these systems can be improved using an IMN system with a small radius of curvature and diameter, and by applying specific operative procedures.

Tibial Stems in Revision Total Knee Arthroplasty: Is There an Anatomic Conflict?

Tibial stems are frequently used in revision total knee arthroplasty (TKA). We investigated the effect of tibial stems on final component alignment and tray position. Thirty 3D reconstructed cadaveric tibial models were classified according to canal bow angle. After virtual implantation of 120 mm and 200 mm stemmed tibial components, deviation from native mechanical axis was measured. Tibial alignment valgus malposition of up to three degrees occurred and most pronounced with 120 mm stems. Canal alignment using 200 mm stems deviated tray position medially and posteriorly. Mild to moderate valgus bowing of the tibial canal is not uncommon (57% in our series) possibly leading to valgus malalignment. Anatomic conflict between the tibial mechanical axis and intramedullary canal can exist, with alignment and tray placement implications.

Analysis of a log periodic nano-antenna for multi-resonant broadband field enhancement and the Purcell factor

Broadband nano-antennas play a central role in many areas of science and technology. However, a more intuitive understanding for rational design of nano-antennas with broadband response is desirable. A log periodic nano-antenna was studied in the paper. The finite-difference time-domain method was used to explore the spectral characteristics of the log periodic nano-antenna by the excitation mode of reception and emission. The effects of geometry on field enhancement and the Purcell factor were systematically described and investigated. The field enhancement of the nano-antenna can be tuned by geometric parameters such as the outer radius, the tooth angle, and the ratio of the radial sizes of successive teeth, which provide control over both the spectral resonance position and the field enhancement peak amplitude. The Purcell factor mainly depends on the outer radius, the tooth angle, and the bow angle. In addition, multi-resonant field enhancement was analyzed in detail by conformal transformation. Furthermore, a careful comparison of the characteristics of a bowtie nano-antenna demonstrated that the log periodic nano-antenna has considerable potential for multi-resonant field enhancement and improvement of the Purcell factor. The results provide a promising prospect for designing and optimizing the log periodic nano-antenna in a broad range of wavelengths.

Bowtie nanoantennas with symmetry breaking

Surface plasmon resonances of optical bowtie nanoantennas with symmetry breaking are studied numerically using the finite-element method. Beginning with both x -axial and y -axial symmetry, bowtie structures are reshaped by varying two parameters (edge lengths and bow angles) to create various symmetries to achieve controllable resonant modes and gap enhancement in the visible and infrared wavelength range. The four edges’ coupling is the main factor contributing to the final fundamental resonances. Double fundamental resonances can be achieved in bowtie structures with x -axial or y -axial symmetry. These properties can guide both the engineering and the fabrication of plasmonic nanoantennas.

A case study of scaling multiple parameters by the violin

This article will present a single case study of the acoustic attributes of sound production techniques that are involved in the expansion of performance practice with the violin. In this study, four elements were chosen from the multidimensional network involved in playing a normal tone, and then each was intentionally decoupled from ordinario. These elements (bow speed, bow placement, bow angle, and bow portion) were scaled between minimal and maximal values for any single parameter. Then, between minimal and maximal values, a series of scalar degrees were chosen to more or less uniformly link these extremes. This article will present acoustical attributes of these methods and discuss implications for musical usage. This study found that decoupling of any single parameter will result in perceptible differences that range from timbral to dynamical (sound) class change.

Modelling archers’ scores at different distances to quantify score loss due to equipment selection and technique errors

Archers lose score through parameters that vary either linearly or quadratically with distance to the target. An archer’s arrow group on the target can be modelled using a normal distribution with the standard deviation depending upon the archer’s skill level and the distance to the target. Structuring the standard deviation to include both a component that varies linearly with distance and another that varies quadratically with distance provides a mechanism to quantify the impact on the archer’s score of various technique and equipment errors. In this article, the impact of wind drift and variable lateral bow angle (bow cant) have been quantified using the archer’s scores at target distances of 70 and 50 m, together with simulation using a Monte Carlo technique.

Assessment of whipping and springing on a large container vessel

Wave induced vibrations increase the fatigue and extreme loading, but this is normally neglected in design. The industry view on this is changing. Wave induced vibrations are often divided into springing and whipping, and their relative contribution to fatigue and extreme loading varies depending on ship design. When it comes to displacement vessels, the contribution from whipping on fatigue and extreme loading is particularly high for certain container vessels. A large modern design container vessel with high bow flare angle and high service speed has been considered. The container vessel was equipped with a hull monitoring system from a recognized supplier of HMON systems. The vessel has been operating between Asia and Europe for a few years and valuable data has been collected. Also model tests have been carried out of this vessel to investigate fatigue and extreme loading, but model tests are often limited to head seas. For the full scale measurements, the correlation between stress data and wind data has been investigated. The wave and vibration damage are shown versus heading and Beaufort strength to indicate general trends. The wind data has also been compared to North Atlantic design environment. Even though it has been shown that the encountered wind data has been much less severe than in North Atlantic, the extreme loading defined by IACS URS11 is significantly exceeded when whipping is included. If whipping may contribute to collapse, then proper seamanship may be useful in order to limit the extreme loading. The vibration damage is also observed to be high from head to beam seas, and even present in stern seas, but fatigue damage in general is low on this East Asia to Europe trade.

Vessel Wave Wake Characterisation Using Wavelet Analysis

This work focuses on characterising vessel wave wake (wash) using wavelet analysis when a vessel is operating in the sub-critical and critical zone. Such characterisation complements other wash characteristics: Froude depth number, bow wave angle, solitons and decay coefficient. The examination of experimental results indicates that differences in characteristics with respect to water depth, Froude depth number, vessel displacement, hull form and soliton generation can be identified through wavelet analysis. The results demonstrate “proof of concept” that wavelet analysis is a powerful tool for characterising vessel wash and captures the effects of key operational and vessel changes.

Wire Saw Process-Induced Surface Damage Characterization

Wire saw process is used to cut concrete, stone, ceramics and almost all kinds of brittle materials with low surface damage and high efficiency. Silicon wafers in semiconductor and photovoltaic industries are generally sliced using wire saw process. Wire saw process induces surface damage to the wafer surface which decreases the wafer quality and increases production costs due to post grinding and polishing. The formation of surface damage was investigated using bonded interface sectioning technique in this study. An experimental parametric study was conducted to relate the process parameters to wire bow angle, distributed wire load and surface damage depth. A non-dimensional damage index is defined which is a function of process parameters. Process recommendations are presented to increase the efficiency without increasing surface damage.

Musicians' Medicine: Musculoskeletal Problems in String Players

There is increasing attention to medical problems of musicians. Many studies find a high prevalence of work-related musculoskeletal disorders in musicians, ranging from 73.4% to 87.7%, and string players have the highest prevalence of musculoskeletal problems. This paper examines the various positions and movements of the upper extremities in string players: 1) basic postures for holding instruments, 2) movements of left upper extremity: fingering, forearm posture, high position and vibrato, 3) movements of right upper extremity: bowing, bow angles, pizzicato and other bowing techniques. These isotonic and isometric movements can lead to musculoskeletal problems in musicians. We reviewed orthopedic disorders that are specific to string players: overuse syndrome, muscle-tendon syndrome, focal dystonia, hypermobility syndrome, and compressive neuropathy. Symptoms, interrelationships with musical performances, diagnosis and treatment of these problems were then discussed.

Abrasive Distribution of the Fixed Diamond Wire in Wire Sawing Process

Fixed diamond wire saw has the advantages such as higher cutting rate and clearer operating environment over the slurry wire saw in wafering. However, the higher cost and poor sliced wafer surface are still the obstacles for the diamond wire saw to totally replace slurry wire saw. In this study, the distribution of diamond grits on the wire was investigated by numerical simulation. The results show that there is a critical value of the abrasive interval to transfer the machining mechanism from plastic plowing to brittle indentation cracking for the material removal. The value depends on both the wire tension and bow angle during the operation.

규칙파 중 갑판침입수 충격하중 감소를 위한 선수형상 설계

In this research, the relationship between the bow shape and green water phenomenon on the bow deck of an FPSO was studied using an experimental method. A 140,000 DWT FPSO was used as the objective hull form in the present research. The incident waves were regular types. The heights were 1.0 and 1.5 times the freeboard, and the length was equal in size to LBP. The wave heights and pressures on the deck were measured in experiments. Model tests were performed to determine the effects of bow flare angles, bow shapes, and a forecastle deck. The free heave and pitch conditions were applied to the models in these experiments. From the results of the model tests, an optimized bow shape was designed, which was found to decrease the green water impact loading. The results of this research could be used as fundamental data in the design of a bow shape.

Geometrical bowing and molecular orientation angle in biaxially stretched poly(ethylene terephthalate) films

AbstractThe aim of this study was to investigate in greater detail the occurrence of geometrical bowing and the average molecular orientation direction in biaxially stretched and annealed film webs and to determine possible causes for these effects at a morphological level. This involved studying the temperature‐dependent behavior of annealed and nonannealed film webs and determining the geometrical bowing and average molecular orientation direction across the working width of the film. The average molecular orientation direction was measured offline using a polarimeter and also online using a novel online orientation sensor. It was shown that the geometrical bowing correlates directly with the amount of film shrinkage in machine direction which occurs during annealing in the transverse direction orienter. In addition, a possible explanation is given for the greater increase in the molecular orientation angle at the film edges compared with the geometrical bowing. Good agreement was found between online and offline measurement of the molecular orientation angle. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

A preliminary study on the key factors contributing to the attractive lips of Chinese children

ObjectiveTo explore the aesthetic characteristics of the Chinese children lips. MethodsFrontal and profile photographs of 653 healthy children were categorized as the attractive and the unattractive by three laypersons and objectively measured for comparison. ResultsThe attractive group tended to be smaller in the upper paramedian red lip height, the lower paramedian red lip height, the midline upper red lip height, the central bow angle, and the lip angle, while greater in the Cupid's bow width. ConclusionsThinner lips seemed to be more attractive than full ones among Chinese children.

규칙파 중 갑판침입수에 미치는 선수 플레어 각도의 영향에 관한 실험적 연구

It is very important to investigate and understand the motion of a FPSO on waves because green water phenomenon occurs owing to the relative motions between incident waves and a ship on them. In this research, both experimental and some numerical approaches have been performed in head sea conditions with regular waves. As an object model of this research, a FPSO model is set free to heave and pitch during the experiments. Also, the motions of the FPSO model which are the results of the experiments are used for the corresponding numerical computations. The purpose of this study is to clarify the effect of bow flare on green water load. In this research, it is found that the amount of green water entered from the side of bow is decreased by the increase of bow flare angle. Moreover, the relation between the green water on the bow upper deck and the impact load on the vertical wall located at turrethead is investigated. The results of this research could be used as one of the fundamental data to design bow flares. Also, an optimized bow flare angle is proposed in this study.

Anthropometric measurements to design best-fit femoral stem for the Indian population.

Background:The standard commercially available marketed prostheses sometimes may not be the best fit to Indian patients because of the large anatomic variation. Orthopedic surgeons always stress the need for a proper implant–patient match in hip joint replacements, in particular, for a cementless femoral stem. The complications of mismatch are aseptic loosening, improper load distribution, and discomfort. The present study was undertaken to compare the differences in dimensions between femurs of elderly Indians and those of populations from other regions in order to solve the problem of a possible geometric mismatch between a selected implant and the hip joint as far as Indian patients are concerned.Materials and Methods:Measurements were made using computer aided design techniques on computed tomography (CT) scanned images of 98 femurs (56 left and 42 right). The software used to convert the CT images into solid models was MIMICS® (Materialize, Inc., Leuven, Belgium). The geometrical parameters, viz., the femoral head offset, femoral head center (HC), femoral head diameter, femoral head relative position, position of shaft isthmus, neck-shaft angle, bow angle, femoral neck length, canal flare index, femoral length, and canal width at various locations, were chosen to design best-fit standard femoral stems for cementless insertion. These data were compared with the published data of other countries.Results:A difference of 16.8% was found in the femoral head offset between Indian and Swiss populations, which can affect soft tissue tension and range of motion. At a distance of 20 mm above the lesser trochanter (LT), the anteroposterior (AP) canal width was found to differ by 45.4%, when compared with a French population which can affect the mechanical stability of femoral stem. Femoral dimensions of Indian male and female subjects have also been compared and differences evaluated. At the LT, the aspect ratio (ratio of mediolateral canal width and AP canal width) in case of males (1.198) is approximately13% higher than that of females (1.059).Conclusions:This study indicates a need for redesign of femoral stems. The obtained anthropometric femoral dimensions can be used to design and develop indigenous hip joint prosthesis in India. The results of this study can also be used in forensic anthropometric studies.

Slamming of ships: where are we now?

Literature published on the problem of ship slamming in waves is reviewed from the point of view of someone working at a ship research institute. Such an institute is confronted with rather practical questions regarding the acceptability of certain design parameters such as the acceptable amount of bow flare angle for use at sea. The importance of these questions is illustrated by noting that actual slamming or the presumed danger of slamming is the main reason for ship operators to reduce speed or to change heading. The review shows that such questions cannot yet be answered. The problem of the local effect of the impact is very complicated owing to the importance of air inclusions, bubbles in the water, compressibility of water and cavitation effects. Only a computational method properly including all these effects will give an accurate answer; also model tests will not be capable of doing this, if only because the methods to extrapolate the results of models to full scale are not yet developed. The problem of the global response of the ship to a wave impact is closer to being solved. A two-stage approach is proposed, consisting of a computational fluid dynamics method for individual impacts and an approximate method to be included in long-term simulations. However, to arrive at a realistic long-term distribution, one has to account for the seamanship of the captain; avoiding the worst conditions or adapting the ship speed and course has a large effect on the actual extremes. Research on this topic has hardly begun.

Design and Simulation of Cutting Optimization and Controller for the Diamond Multi-Wire Sawing System

The purpose of this paper is to investigate the effect of ablation parameters on the ablation characteristics for the fixed diamond multi-wire sawing by using Taguchi method. Meanwhile, using the optimal ablation parameters, we accomplish the cutting dynamic analysis and controller design of the diamond multi-wire sawing system. In this paper, we apply the Chemical Mechanical Polishing (CMP) theorem to derive the ingot profile and cutting rate equations of the diamond multi-wire sawing system. The characteristics discussed in this paper include ingot profile variance, cutting rate. The ablation parameters are tension force, wire velocity, cutting force, width of the kerf. The orthogonal array, signal-to-noise (S/N) ratio and analysis of variance (ANOVA) are employed to analyze the effect of these ablation parameters. In the meantime, we use the optimal ablation parameters to accomplish the controller design of the diamond multi-wire sawing system, include diamond high-speed control of the main roller in the cutting system, cutting rate control and the moving wire bow angle holding.

Flow fields and losses downstream of an ultra-highly loaded turbine cascade with bowed blades

For the first time, a systematic experimental investigation on flow fields and losses of an ultra-highly loaded turbine cascade with bowed blades has been conducted. Flow patterns, secondary flow vortices and vectors, losses, and yaw angles at the downstream outlet have been analysed based on the measurements. The results show that the flow fields downstream of the cascade are characterized by a complicated vortex structure including passage vortices (PVs), trailing edge vortices (TVs), and corner vortices (CVs). The high-loss cores at the cascade outlet roughly correspond to the high-vorticity regions. A −20° bow angle gives the optimal aerodynamic performance under the conditions of this work, but the overall improvement is not significant. Appropriate negative blade bowing weakens the PVs and TVs and prevents the meeting and mixing of the PVs at the midspan, hence improving the flow fields and reducing the overall losses. However, negative blade bowing also increases the flow separation in corner regions, and enhances the CVs and the accumulation of low-energy air flow. This partially counteracts the beneficial effects, making the overall improvement not significant. The pitch-averaged yaw angle at the outlet of the cascade varies dramatically over the whole span. Negative blade bowing can improve the uniformity of the yaw angle distribution at the outlet. On the contrary, positive blade bowing degrades the aerodynamic performance of the cascade.

Surface plasmon resonances in silver Bowtie nanoantennas with varied bow angles

Plasmon resonances in silver Bowtie nanoantennas have been numerically and experimentally investigated with varying the bow angle. Finite-difference time-domain simulation demonstrates one fundamental and two types of high-order resonances. With the increase in the bow angle, the peak of the fundamental resonance first blueshifts, and then redshifts. Two types of high-order resonances, which are prone to be excited at large bow angles, are assigned to the charge/current oscillations either between the corners or between the edges of the nanoprisms. Experimentally, far-field extinction measurement to lithogragphically fabricated Bowtie nanoantenna arrays corroborates our interpretation. As far as a 300 nm long, large angle silver Bowtie antenna is concerned, the resonances appear at the wavelengths of ∼830, ∼600, and ∼400 nm, respectively, in accordance with the simulation. The spectrally resolved multiple resonances illustrate the diversity of the excitation in optical nanoantennas and imply potential applications in nanophotonics.