Degrees Of Deflection Research Articles

Study on high-pressure hydrogen leakage characteristics under different shapes of nozzles

In this paper, numerical simulations and experimental methods are utilized to investigate the near-field jet structures and far-field concentration distributions after the release of circular, equilateral triangular, square, and rectangular (AR2, AR4, AR8) nozzles. For all nozzle shapes, the hydrogen concentration along the jet centerline is inversely proportional to the distance from the nozzle. Circular nozzles exhibit the slowest decay of hydrogen concentration along the jet centerline, while rectangular nozzles show the fastest decay. Under the studied pressures, the concentration distributions along the jet centerline after the release of all nozzles are summarized into an equation. For the near-field jet structure, all nozzle except the circular nozzle experience varying degrees of deflection. When the aspect ratio is greater than or equal to 4, the Mach disk cannot be formed. An empirical formula for the position of the shock waves of the rectangular nozzle jet is proposed.

In vitro Comparison of the Mechanical and Optical Characteristics of 5 Disposable Flexible Ureteroscopes

Introduction: Disposable (single-use) flexible ureteroscopes are alternatives to reusable ureteroscopes. With their superior surgical efficacy and safety in the presence of upper urinary calculi, disposable ureteroscopes aim to overcome the main limitations of conventional reusable ureteroscopes. However, studies on the performance of the most recently developed models of single-use flexible ureteroscopes are scarce. This study aimed to compare the in vitro performance of several recently introduced, single-use, flexible ureteroscopes. Methods: Five disposable flexible ureteroscopes were tested in vitro to evaluate their mechanical and optical characteristics. To this end, their degrees of deflection, irrigation flow rates, and image qualities were investigated. The models examined were Innovex US31-B12, OTU-100RR, Redpine RP-U-C12, Sciavita SUV-2A-B, and Seplou URS3016E. Their performance was also compared with that of a reusable flexible ureteroscope, Olympus URV-F. Results: The OTU device had the highest degrees of deflection and the smallest loop diameter of the disposable ureteroscopes. The single-use ureteroscopes had identical image resolutions at a distance of 1 cm. The Innovex and Redpine devices had the best color representation. Conclusions: Of the tested disposable ureteroscopes, the OTU device had the best mechanical attributes, given its small loop diameter, high deflection angles, and low irrigation flow loss. As to their optical properties, the resolutions of all 5 single-use models were identical at an image distance of 1 cm.

Micromechanical study of nano-cutting metal-ceramic WC/Cu by diamond tools

In this paper, the effect of the distribution of ceramic particles WC in Cu matrix on the nano-cutting behavior was investigated using molecular dynamics, and the cutting force, friction coefficient, machined surface quality, sub-surface damage depth, atomic displacement and internal defects were systematically studied, and the performance comparison at different cutting speeds was also investigated. It was found that due to the location of the WC phase, the overall removal of the material by the tool can be divided into the following three ways: When WC particles are above the cutting plane, there is less fluctuation in cutting forces and friction coefficients, and less impact on machined surface and subsurface damage; When the WC particles are below the cutting plane, the fluctuation of cutting force and friction coefficient is slow. Meanwhile, shallow craters are produced at the WC location; When the center of mass of WC particles is on the same level as the cutting plane, the cutting force and friction coefficient fluctuate drastically, the quality of the machined surface deteriorates sharply, and at the same time the hard particles pulled out by the tool remain on the machined surface. It was also found that the WC particles underwent different degrees of counterclockwise deflection in the three stages and caused a diversion of the atomic displacement in front of the tool. In addition, different degrees of dislocation plugging are formed between the WC and the tool at different positions, and the density of dislocation lines increases, which makes the substrate near the WC particles strengthened.

Novel Approach of Airfoil Shape Representation Using Modified Finite Element Method for Morphing Trailing Edge

This study presents a novel approach to parameterize the geometry of a morphing trailing-edge flap that allows its aerodynamics to be optimized while capturing the expected structural behavior of the flap. This approach is based on the finite frame element method, whereby the initial flap surface is defined as a structure with constraints that are similar to those of a morphing flap with passive skin. The initial shape is modified by placing a series of distributed loads on the surface. The finite frame element method is modified with rigid rotation corrections to maintain the initial element length without requiring nonlinear calculations and to achieve accurate surface-length results by only solving the linear FEM equations twice. The proposed method enables the shape of the morphing flaps to be rapidly formulated while maintaining the initial upper surface-length and trailing-edge angle. The constraints are inherently integrated into the algorithm, eliminating the need for unnecessary feasibility checks during the aerodynamic optimization. By using the proposed airfoil parameterization method, a case study was conducted by using a genetic algorithm to optimize the lift-to-drag ratio of the NACA 23012 airfoil flap starting at 0.7c with 10 degrees of deflection. The optimizer resulted in a structurally feasible morphing flap that achieved a 10% increase in the lift-to-drag ratio in the optimized angle of attack range.

Mixed-mode fracture model to quantify local toughness in nacre-like alumina

With the progress of ceramic engineering, tough technical ceramics such as nacre-like alumina now exhibit complex fracture patterns with high degrees of deflection, branching and bridging. If these mechanisms highly contribute to improving crack resistance, the crack geometries go beyond the hypotheses assumed in standard techniques to quantify toughness, making it difficult to understand the mechanisms responsible for crack propagation. We report a robust local solution based on a combination of analytical formulas and finite element analysis to accurately estimate the effective stress intensity factors at the tips of multiple deflected cracks. The influence of sample size on local R-curves is analysed and shown to be less important relative to standard methods. We use this method to evaluate the direct influence of zirconia nanoparticles in the nacre-like structure and highlight the role of these findings in the understanding of mechanical response and future optimisation of highly textured tough ceramics.

Rolling bearing condition monitoring method based on multi-feature information fusion

In machining operations, the misalignment of the bearing assembly or imbalanced load often leads to deflection and failure of the tool spindle. The use of single feature information does not accurately monitor the complex working conditions. Considering this, this paper proposes a rolling bearing running condition monitoring method which is based on multiple feature information. Firstly, a multi-dimensional feature matrix is obtained by extracting the features of a single type of raw data in the time domain, frequency domain, and time-frequency domain, and then the dimensionality of the matrix is reduced by principal component analysis (PCA). An entropy weight improved the D-S(EWID-S) evidence theory is proposed. By updating the initial evidence source, and applying the Euclidean distance of the spatial centroid, the fusion results were evaluated. Finally, a test rig for eccentric bearing load operation is developed to obtain the vibration signals at two distinct locations and to confirm the proposed method. The test results show that the condition monitoring method based on the PCA and EWID-S evidence theory can effectively identify the bearing operating at different degrees of deflection. At the same time, by comparing with other improved D-S evidence theory methods, it is verified that this method has more advantages in information fusion and bearing condition monitoring.

Application of dorsal foot hexagonal flap for reconstruction of web space in fourth and fifth toe syndactyly combined with polydactyly

To explore the application of the dorsal foot hexagonal flap for reconstruction of the web space in the fourth and fifth toe syndactyly combined with polydactyly. Between May 2016 and October 2019, 27 patients (34 feet) with the fourth and fifth toe syndactyly combined with polydactyly were treated, including 12 males and 15 females with an average age of 22.8 months (range, 10 months to 8 years). There were 7 bilateral feet and 20 unilateral foot. Twenty-four of which were incomplete and 10 were complete syndactyly of the fourth and fifth toes, and the fifth toes showed various degrees of fibular deflection. All the 34 feet were treated with one-stage reconstruction of the toe web with the dorsal foot hexagonal flap, and the correction of the fibular deviation of the fifth toe was made by removing the tibial polydactyly and using the articular surface dressing or wedge osteotomy. All wounds healed by first intention without skin-frafting. All patients were followed up 6-36 months (mean, 18 months). There was no flexion contracture and obvious scar hyperplasia in all the patients, and the width and slope of the toe webs were normal. Three of the 34 webs developed web creep, and the rest of the toe webs were normal in depth. All 34 feet were corrected with peroneal fibular deviation, and the function of toe flexion was good. All parents of the children were satisfied with the outcome. The reconstruction of toe webs with dorsal foot hexagonal flaps for the treatment of the fourth and fifth toes syndactyly combined with polydactyly requires no skin graft. The operation is simple with high survival rate of the flap, the appearance and function of the toes are good, and the effectiveness is satisfactory.

The effect of laser fiber on the damage of the working channel of a flexible ureteroscope

IntroductionFlexible ureteroscopy involves expensive equipment that is expensive to repair. This study aimed to investigate the effects of cleavage by various tools on the laser fiber tip and to determine the extent of damage incurred to the laser passing through the working channel and firing at different degrees of deflection. Materials and methodsWe investigated the effect of cleavage on Lumenis Slimline reusable fibers (272 and 365 μm) as performed by four cleavage tools: a scribe pen, a surgical blade, suture scissors, and ceramic scissors. Following cleavage, we recorded the pattern of light dispersion and power output. The laser fibers passed through the working channel at various. ResultsThe ceramic scissors provided the best pattern of light dispersion and the highest power output. The suture scissors provided unacceptable levels of light dispersion. The 272 μm fiber was able to pass through the working channel at 30 and 45 degrees of deflection. The 365 μm laser fiber was only able to pass through the working channel at 30 degrees of deflection. There was no breakage of the laser fiber at any of the degrees of deflection evaluated. ConclusionsAnalysis showed that the ceramic scissors were the best tool for cleaving Lumenis Slimline reusable fibers and that suture scissors were unacceptable. We also found that the deflection angle that causes damage to the working channel by laser insertion is dependent on both the size of the laser fiber and the degree of bending. Firing the laser during scope deflection could be performed safely at any degree of deflection, even with a high laser power of 40 W for a duration of 30 s

Sodium alginate-chitosan hydrogel-based soft ionic artificial muscle with different moisture content

Due to the efficiency of ion movement is greatly affected by moisture environment, this article explores the effects of the changing the moisture content of the self-degraded ionic hydrogel-based electrolyte layer made of sodium alginate and chitosan on the improvement of the electromechanical properties of the soft ionic actuator. Specifically, sodium alginate-chitosan ionic hydrogel-based soft ionic actuator is fabricated and analyzed by voltammetry analysis, AC impedance, charge and discharge, electrical conductivity, displacement, and output force. Furthermore, the further application of this soft ionic actuator on bionic flytrap is developed and discussed. The results show that soft ionic actuator with the moisture content of 78.64% has the best electromechanical properties. Furthermore, soft ionic actuators with different moisture contents show different degrees of deflection due to the shift of the anions to the cathode under charged conditions. Therefore, it can be found that moisture content is beneficial to improve the electromechanical properties of ionic hydrogel-based soft artificial muscle.

The mechanical behaviors and energy absorption mechanisms of Al–Cu–Mn alloy under dynamic penetration at wide temperature ranges and large angles

The dynamic behaviors of 2A12 aluminum alloy under dynamic impact and its energy absorption mechanisms under dynamic penetration at wide temperature ranges and large angles were examined using experiments, simulations and theoretical model predictions; a mathematical dynamic energy absorption model was established based on the results of these experiments and simulations. The results indicate that, at impact temperatures lower than 150 °C, the strain rate hardening of the material prevailed; at impact temperatures higher than 250 °C, the strain rate hardening of the material appeared to be regionalized. At different penetration angles, the bullet displayed different degrees of deflection and the bullet hole also appeared in different forms: At penetration angles lower than 20°, the bullet was inversely deflected and the bullet hole was V-shaped; at penetration angles higher than 40°, the bullet hole looked like a convex or concave thumb. Errors between the simulated and numerically calculated energy absorption efficiencies were within the permissible limit of error in all cases, and were all smaller than 10% when the penetration angle was higher than 30°. This suggests that our mathematical dynamic energy absorption model is more accurate in predicting larger penetration angles.

System-based modelling of a foiling catamaran

In the last decades, the use of foils on sailing yacht has highly increased. Whether they are mono or multihull, yachts are using foils to reduce their drag forces and then, to increase their speeds in a large range of wind and sea conditions. Several CFD-based studies have already been carried out in order to optimize the foil's shape and location on the hull, but feedbacks on the yacht's behavior is mainly given by the crew when sailing at sea. The aim of the present paper is to propose a complementary and faster approach that could help to predict and quantify the yacht behavior in calm water and in waves while sailing under foil's action. This approach is well known as a system-based modelling and is a mathematical method that leads to understand the complexity of a system from the study of its interactions in their entirety. The paper will present the ability of the system-based approach to predict the attitude of a catamaran while performing maneuvers such as turning circles with 35 degrees of rudder deflection and zigzag tests 10-10 and 20-20 for different initial Froude numbers and foil's shapes.

Characterization of environmental loads related concrete pavement deflection behavior using Light Detection and Ranging technology

Repeated deflection behavior resulting from temperature and moisture variations across concrete pavement depth causes curling and warping of Portland cement concrete (PCC) pavement systems. Although curling and warping issues have been investigated extensively, there are no standardized methods or procedures currently available to characterize the degree/magnitude of this in situ environmental load-related deflection. This study discusses the development of a detailed procedure for assessing environmental load-related deflection of concrete pavement using a Light Detection and Ranging (LiDAR) system. LiDAR systems have been recognized as an advanced technology for transportation infrastructure inspection but have not been widely investigated for measuring environmental load-related deflection of concrete pavements. In this study, field surveys were conducted on six identified concrete pavement sites in Iowa by scanning the concrete slab surfaces using the stationary LiDAR instrument. Based on dense point cloud data obtained by the LiDAR instrument, a data processing algorithm was developed to obtain the degrees of environmental load-related deflection. The degrees of deflection obtained were correlated to variations in pavement performance, mix design, pavement design, and construction details at each site. The results and findings from this study describe a potentially novel method of using LiDAR system for environmental load-related deflection characterization of concrete pavement.

Cylindrical cross-axis flexural pivots

The cylindrical cross-axis flexural pivot (CCAFP) is proposed as an ultra-compact flexure capable of being integrated into hollow cylindrical shafts, enabling shaft motion without inhibiting cables or other components inside the shaft. Mechanism geometry, materials, and manufacturing are proposed and the results analyzed and tested. A parametric finite element model of the CCAFP was created to analyze the force-deflection and strain-deflection relationships and the predicted behavior was verified by experiment. Analytic models of stress-limiting cam-surfaces suggest even larger motions may be possible when not limited by current practical constraints. The CCAFP is demonstrated and tested at multiple size scales and in multiple materials, ranging from 28.6mm diameter 4130 steel (achieving 9 degrees of angular deflection) to 3mm diameter NiTi (achieving an angular deflection of 85 degrees). The results are generalized to apply to a range of applications, and the CCAFP particularly shows promise for implementation in minimally invasive surgical instruments to decrease instrument size while maintaining instrument performance.

Fiberoptic Contact-Force Sensing Electrophysiological Catheters: How Precise Is the Technology?

Contact-force (CF) sensing catheters are increasingly used in electrophysiological procedures due to their efficacy and safety profile. As data about the accuracy of fiberoptic CF technology are scarce, we sought to quantify it using in vitro experiments. A force sensor was built with a flexible membrane to allow exact reference force measurements for each set of experiments. A TactiCath Quartz (TCQ) ablation catheter was brought in contact with the force sensor membrane in order to compare the TCQ force measurements to sensor reference force measurements. Measurements were performed at different tip angles (0°/perpendicular contact, 45°, 90°/parallel contact), with fluid irrigation, different degrees of catheter deflection, and using a sheath. The accuracy of the TCQ force measurements was 0.9 ± 0.9 g (0°), 0.8 ± 0.8 g (45°) and 1.2 ± 1.3 g (90°), 0.8 ± 0.7 g (irrigation), 0.8 ± 0.8 g (deflection), and 0.8 ± 0.9 g (sheath); this was not significantly different among all experimental conditions. The precision was ≤3.8%. CF measurements using a fiberoptic sensing technology show a high level of accuracy and precision, without being significantly influenced by tip angle, fluid irrigation, catheter deflection or use of a sheath.

Design of an Ureteropyeloscope1

Kidney stones are a hard mass of insoluble calcium deposits found in the urinary system [1]. Depending on the location of the stones, they may cause discomfort and their removal eases the patient from it [1]. Ureteroscopy is a urologic treatment which often uses minimally invasive instruments to access the regions where the stones are located [2]. Minimally invasive procedures have benefited from technological advancements resulting in shorter recovery time and reduced patient scarring. This paper discusses the design of an ureteropyeloscope. The design of the ureteropyeloscope is based on clinical and mechanical requirements. The conceptual design of the ureteropyeloscope is evaluated in-silico and via simulations. The results of the simulations are given and discussed to evaluate the working parameters and conditions. Objectives of the study are as follows:

Biomechanical Evaluation of Subtalar Fusion: The Influence of Screw Configuration and Placement

Common surgical procedures for subtalar fusion include joint resection, autologous bone grafting, and osteosynthesis with screws in a parallel screw configuration. Although fusion is a routine procedure, the reported rates of nonunion have been high. The present study assessed different screw configurations in terms of their rotational and bending stability in an artificial bone model and cadaver bone. Arthrodesis was always performed with 2 screws. Three different screw configurations were tested: parallel, counter-parallel, and a delta configuration. Two different screw designs were used: a cannulated, partially threaded screw (6.5-mm and 8.0-mm diameter) and a solid screw with a different thread design. Eight experimental groups were investigated as pilot studies in artificial bones and then 3 groups in cadaver bones. The parameters were the primary stiffness and deflection of the construct for loads simulating the internal–external rotation and supination–pronation. Delta positioning of the screws resulted in the greatest biomechanical stiffness and the lowest degrees of deflection of the arthrodesis in the artificial bones and cadaver bones. Increasing the screw diameter from 6.5 to 8.0 mm resulted in no additional stability of the arthrodesis in the artificial bones. The results of the present study have indicated that the delta configuration for arthrodesis results in the greatest construct stiffness and lower relative deflection between the talus and calcaneus in the positions tested.

Multistrand, Fast Reaction, Shape Memory Alloy System for Uninhabited Aerial Vehicle Flight Control

This paper details an investigation of shape memory alloy (SMA) filaments which are used to drive a flight control system with precision control in a real flight environment. An antagonistic SMA actuator was developed with an integrated demodulator circuit from a JR NES 911 subscale UAV actuator. Most SMA actuator studies concentrate on modeling the open-loop characteristics of such a system with full actuator performance modeling. This paper is a bit different in that it is very practically oriented and centered on development of a flight-capable system which solves the most tricky, practical problems associated with using SMA filaments for aircraft flight control. By using well-tuned feedback loops, it is shown that intermediate SMA performance prediction is not appropriate for flight control system (FCS) design. Rather, capturing the peak behavior is far more important, along with appropriate feedback loop design. To prove the system, an SMA actuator was designed and installed in the fuselage of a 2 m uninhabited aerial vehicle (UAV) and used to control the rudder through slips and coordinated turns. The actuator was capable of 20 degrees of positive and negative deflection and was capable of 7.5 in-oz (5.29 N cm) of torque at a bandwidth of 2.8 Hz.

Study Effect of Deflection on the Progress of Cracking in Aluminum with Different Heat Treatment

In the designing of many mechanical parts especially in the aerospace, naval, automotive industry, military, etc., one of the most important designing stages which needs special attention is investigating the Fatigue Damage, because the reasons for most of the fractures which happen during the service is the phenomenon of Fatigue. However, there is no visible evident change in the structure of the parts; it seems that the fracture happens quite suddenly and without any prior alerts. The stages of fatigue are the nucleation of crack on surface (for most metals) and propagation towards the inside of the part until the fracture. It is important to investigate the progress of the cracks in different materials and different heat treatment and end finishing under various loadings and in different environmental and service conditions of the parts in order to estimate the life of the parts according to the phenomenon of Fatigue. The aim of this article is to calculate the crack growth rate in aluminum sheets with different treatment such as extrusion and forging that are cracked with different degrees of deflection. For this purpose cracked different 7075 and 7050 Aluminum alloy plates (with an elliptical crack in the middle of the plate) with the ratio of great diagonal to short diagonal of the ellipse as 1, 9, 1/9, 5 and 1/5 were simulated by a software named ‘AFGROW’. Then the crack growth rates in aluminum parts are analyzed applying same conditions (defining the coefficients of Forman’s equation). Finally by comparing the result curves from the analyses in each group of materials with certain treatment, the effect of the degree of cracks deflection and the growth rate is discussed. Also for a specific notch, the crack growth rates in aluminum sheets are compared.

Debonding force and deformation of two multi-stranded lingual retainer wires bonded to incisor enamel: an in vitro study

The aim of the study was to examine, in vitro, the effect of a vertical force on the debond force and deformation of two multi-stranded wires bonded to the lingual enamel of lower incisor teeth. Two different stainless steel wires were used, 0.016 × 0.022 inch (Bond-A-Braid® Reliance Orthodontic Products) and a three-stranded 0.0175 inch wire (Ortho Technology). An in vitro model was used to simulate a vertical force at the interdental wire. Twenty-six pairs of incisors were placed in two groups. A 15 mm length of wire was bonded to the lingual surfaces of each pair of incisors using a common bonding technique. A vertical force was applied to the midpoint of the interdental wire, using an Instron universal testing machine. The failure characteristics examined included the maximum force for debond, the degree of wire deformation, and the site of failure. Significance was predetermined at P < 0.05 and multiple comparisons indicated no significant differences (P = 0.147) in the initial mean bond strength between the 0.0175 inch (41.44 N) and 0.016 × 0.022 inch (37.70 N) wires. The main failure type for both the initial and second debond events was fracture of composite bond at the wire-composite interface, cohesive failure. Both wires exhibited similar mean degrees of deflection of 1.30 and 1.51 mm for the 0.0175 inch and 0.016 × 0.022 inch wires, respectively. Rebonding to enamel resulted in significantly lower (P = 0.001) mean bond strength for both wires, 0.0175 inch (13.86 N) and 0.016 × 0.022 inch (14.17 N) in comparison with the initial bond strength. Rebonding to previously bonded enamel may be unpredictable and may lead to higher failure rates of bonded lingual retainers.

Characterization of Primary Cilia in Human Airway Smooth Muscle Cells

Considerable evidence indicates a key role for primary cilia of mammalian cells in mechanochemical sensing. Dysfunctions of primary cilia have been linked to the pathogenesis of several human diseases. However, cilia-related research has been limited to a few cell and tissue types; to our knowledge, no literature exists on primary cilia in airway smooth muscle (ASM). The aim of this study was to characterize primary cilia in human ASM. Primary cilia of human bronchial smooth muscle cells (HBSMCs) were examined using immunofluorescence confocal microscopy, and scanning and transmission electron microscopy. HBSMC migration and injury repair were examined by scratch-wound and epidermal growth factor (EGF)-induced migration assays. Cross-sectional images of normal human bronchi revealed that primary cilia of HBSMCs within each ASM bundle aggregated at the same horizontal level, forming a "cilium layer." Individual cilia of HBSMCs projected into extracellular matrix and exhibited varying degrees of deflection. Mechanochemical sensing molecules, polycystins, and alpha2-, alpha5-, and beta1-integrins were enriched in cilia, as was EGF receptor, known to activate jointly with integrins during cell migration. Migration assays demonstrated a ciliary contribution to HBSMC migration and wound repair. The primary cilia of ASM cells exert a role in sensing and transducing extracellular mechanochemical signals and in ASM injury repair. Defects in ASM ciliary function could potentially affect airway wall maintenance and/or remodeling, possibly relating to the genesis of bronchiectasis in autosomal dominant polycystic kidney disease, a disease of ciliopathy.