Step Angle Research Articles

Effect of Step Depth and Angle on the Aerodynamics of a Sliding Morphing Skin

The past two decades have witnessed a growing interest among aerospace researchers and designers in aircraft morphing technology. A single aircraft with morphing wings can perform near optimum at different flight regimes by changing the geometry of its wings. With the advancements achieved in this field, a need for a reliable morphing skin is emerging. The demanding task of designing a morphing skin has to compromise between flexibility to ensure low actuation requirements, and high stiffness to carry all the aerodynamic loads. One of the viable designs that fulfills the mechanical requirements is the segmented sliding skin. In such a design, discrete panels overlap to cover the surface of the wing and slide against each other during the morphing motion. From the aerodynamic perspective, the sliding panels introduce backward-facing steps on airfoil surface. In the process of determining the optimum panels’ thickness, this paper presents a comprehensive numerical study on the effect of the step depth and angle on the aerodynamics of an airfoil with a backward-facing step employed on its lower surface. Results showed a significant improvement in the lifting capabilities of the stepped airfoil, and this improvement is directly proportional to the step depth. On the other hand, the separated flow at the step edge induced a low pressure recirculation zone that created a suction force directly proportional to the effective area of the backward-facing step. This resulted in a drag coefficient value that is directly proportional to the step depth. The aerodynamic efficiency of the stepped airfoil was degraded in terms of the lift-to-drag ratio, however decreasing the step depth largely mitigated these adverse effects. Studying different step angles showed that the step can be tilted over a wide range of angles with a negligible effect on the aerodynamics of the stepped airfoil.

Fractures of the Distal Radius: A Randomized Controlled Trial of 180 Patients Comparing Volar Locking Plates and Alternative Fixation Methods

For intra-articular and extra-articular distal radius fractures do volar locking plates (VLP) provide patients with functionally, clinically and radiologically superior results compared to fixation methods before their introduction; Kirschner wires, non-locking plates and external fixators? In this prospective, randomized controlled trial 180 participants with a median age of 65 (range 18-96) were followed up for 1 year. Outcome measures included Disability of Arm Shoulder and Hand (DASH) score, range of motion (ROM) and grip strength, radiological measurements (radial length, angle, tilt, ulnar variance and articular step) and complications. There was no statistical difference of DASH scores between groups at any time point. ROM differed at one and six weeks post operatively, favoring the VLP fixation. However these results were not sustained at 12 and 52 weeks. The results have confirmed VLP’s ability to maintain fracture reduction over 12 weeks compared to alternative fixation methods.

Compressed-sensing (CS)-based Image Deblurring Scheme with a Total Variation Regularization Penalty for Improving Image Characteristics in Digital Tomosynthesis (DTS)

In this work, we considered a compressed-sensing (CS)-based image deblurring scheme with a total-variation (TV) regularization penalty for improving image characteristics in digital tomosynthesis (DTS). We implemented the proposed image deblurring algorithm and performed a systematic simulation to demonstrate its viability. We also performed an experiment by using a table-top setup which consists of an x-ray tube operated at 90 kV p, 6 mAs and a CMOS-type flat-panel detector having a 198-μm pixel resolution. In the both simulation and experiment, 51 projection images were taken with a tomographic angle range of θ=60 o and an angle step of Δθ =1.2 o and then deblurred by using the proposed deblurring algorithm before performing the common filtered-backprojection (FBP)-based DTS reconstruction. According to our results, the image sharpness of the recovered x-ray images and the reconstructed DTS images were significantly improved and the cross-plane spatial resolution in DTS was also improved by a factor of about 1.4. Thus the proposed deblurring scheme appears to be effective for the blurring problems in both conventional radiography and DTS and is applicable to improve the present image characteristics.

Design and experimental verification of single-layer high-efficiency transmissive phase-gradient metasurface

Polarization characteristic is an important feature of electromagnetic (EM) wave. Manipulating polarization state and controlling propagation direction of EM wave by phase-gradient metasurface (PGM) have become a research hotspot in recent years. However, using transmissive PGM for polarization manipulation often suffers a low efficiency. To alleviate this problem, multilayered structure was utilized. However, it often suffered bulky volume and design complexity. Therefore, engineering a thin high-efficiency transmissive PGM with polarization manipulation is a pressing and challenging issue. In this paper, a single-layer high-efficiency transmissive PGM with cross-polarization conversion and anomalous refraction is designed. To illustrate the working mechanism, the PGM is comprehensively investigated through theoretical analysis, EM simulations and experimental measurements. The unit cell evolving from an electric-field-coupled resonator is carefully designed to exhibit a Pancharatnam-Berry phase gradient. Each rotated element irradiated separately by the normally-incident left-handed circularly polarized (LHCP)and right-handed circularly polarized (RHCP) waves is simulated in CST microwave studio. The results show that the cross-polarization transmission magnitude keeps over 0.9 and does not change as the rotation angle varies. Moreover, the phase shift is twice the rotation angles and the direction of refracted beam is opposite under the above two different polarizations. In addition, the cross-polarization conversion ratio is above 0.9 from 14 GHz to 15.8 GHz. On the premise of high transmission magnitude, the phase of the cross-polarized transmission can be freely manipulated via varying axis orientation. By spatially arranging six unit cells in rotation angle steps of 30, a PGM with a phase difference of 60 between adjacent unit cells is designed. As is well known, linearly-polarized (LP) EM waves can be decomposed into LHCP and RHCP waves with equal amplitudes. Therefore, an LP wave through the PGM will be separated into two counterpropagating CP waves. The high-efficiency anomalous refraction of the PGM is verified from simulated near-field electric field distributions and far field normalized power patterns. The simulated refracted angle is 33.5, which is in accordance with the theoretical designed value (33.75). Moreover, the transmissive power intensity spectrum under the normally-incident LP waves is simulated and measured. The simulated and measured results are in good agreement with each other, showing that the transmitted wave is perfectly split into two counterpropagating waves from 14.9 GHz to 15.3 GHz. Compared with the available transmissive PGMs, our proposed PGM features high efficiency and thin structure with only single layer, making the proposed PGM a promising alternative to manipulating propagation and polarization of EM waves.

Stepper Motor Control by ATMEL AVR Microcontroller

The paper deals with stepper motor control using microcontroller ATmega8-16PU. In the paper are mentioned two ways of control, namely full-step mode and half-step mode control. At first, bipolar stepper motor is introduced. Next, there is created measuring stand consisting of bipolar stepper motor with one step angle 1.8° and encoder with 360 CPR. During the experiment were measured angular velocities by I/O measuring card MF624 cooperating with Matlab/Simulink. The results show differences between used two stepping modes of motor.

Plagioclase Growth Rates Control Three-grain Junction Geometry in Dolerites and Gabbros

Measurements of dihedral angles at three-grain junctions in gabbros, involving two grains of plagioclase and one grain of another mineral, demonstrate that the median dihedral angle is generally the same for all minerals in any sample. The few exceptions to this can be attributed to reaction or to the cessation of growth of plagioclase during the last stages of solidification of highly evolved liquids that do not crystallize volumetrically important amounts of plagioclase. The dihedral angle is therefore primarily controlled by the growth behavior of plagioclase in the last remaining liquid. The final value of the dihedral angle is controlled by the extent to which plagioclase growth is accommodated on the (010) faces: low angles form when growth on the (010) faces is minor compared with that on the other growth faces, and high angles form when the (010) faces accommodate significant growth. The response of dihedral angles to changes in crystallization time is therefore explained by the changing response of plagioclase growth to cooling rate, with limited growth on (010) faces during rapid cooling (leading to a low dihedral angle) and more significant growth at slow cooling (leading to high dihedral angle). The correspondence between dihedral angle and plagioclase grain shape (as quantified by the average apparent aspect ratio observed in thin section) is clearly evident for non-fractionated bodies such as dolerite sills. Although the stratigraphic variation of the overall plagioclase grain shape in the floor cumulates of the Skaergaard Intrusion is broadly similar to that observed in sills, there is no correspondence to observed augite�plagioclase�plagioclase dihedral angles, which show a step-wise stratigraphic variation, corresponding to changes in the liquidus assemblage. This decoupling occurs because plagioclase growth in layered intrusions occurs in two stages, the first at, or close to, the magma�mush interface and the second within the mush. Chemical maps of samples on either side of the augite-in dihedral angle step demonstrate a step-wise change in the aspect ratio of the plagioclase grown during the second stage, with the aspect ratio of this stage corresponding to that predicted from the dihedral angles. Plagioclase shape in layered intrusions thus records two separate thermal regimes, with the overall shape controlled by the global cooling rate of the intrusion, and the second (minor) stage within the mushy layer reflecting local thermal buffering controlled by the liquidus assemblage of the bulk magma. Dihedral angles in layered intrusions record the second thermal regime.

Physical constraints, fundamental limits, and optimal locus of operating points for an inverted pendulum based actuated dynamic walker

The inverted pendulum is a popular model for describing bipedal dynamic walking. The operating point of the walker can be specified by the combination of initial mid-stance velocity (v0) and step angle () chosen for a given walk. In this paper, using basic mechanics, a framework of physical constraints that limit the choice of operating points is proposed. The constraint lines thus obtained delimit the allowable region of operation of the walker in the v0– plane. A given average forward velocity can be achieved by several combinations of v0 and . Only one of these combinations results in the minimum mechanical power consumption and can be considered the optimum operating point for the given . This paper proposes a method for obtaining this optimal operating point based on tangency of the power and velocity contours. Putting together all such operating points for various , a family of optimum operating points, called the optimal locus, is obtained. For the energy loss and internal energy models chosen, the optimal locus obtained has a largely constant step angle with increasing speed but tapers off at non-dimensional speeds close to unity.

3D reconstruction based on compressed-sensing (CS)-based framework by using a dental panoramic detector

In this work, we propose a practical method that can combine the two functionalities of dental panoramic and cone-beam CT (CBCT) features in one by using a single panoramic detector. We implemented a CS-based reconstruction algorithm for the proposed method and performed a systematic simulation to demonstrate its viability for 3D dental X-ray imaging. We successfully reconstructed volumetric images of considerably high accuracy by using a panoramic detector having an active area of 198.4 mm × 6.4 mm and evaluated the reconstruction quality as a function of the pitch (p) and the angle step (Δθ). Our simulation results indicate that the CS-based reconstruction almost completely recovered the phantom structures, as in CBCT, for p≤2.0 and θ≤6°, indicating that it seems very promising for accurate image reconstruction even for large-pitch and few-view data. We expect the proposed method to be applicable to developing a cost-effective, volumetric dental X-ray imaging system.

Step angles to reduce the north-finding error caused by rate random walk with fiber optic gyroscope.

We study the relationship between the step angles and the accuracy of north finding with fiber optic gyroscopes. A north-finding method with optimized step angles is proposed to reduce the errors caused by rate random walk (RRW). Based on this method, the errors caused by both angle random walk and RRW are reduced by increasing the number of positions. For when the number of positions is even, we proposed a north-finding method with symmetric step angles that can reduce the error caused by RRW and is not affected by the azimuth angles. Experimental results show that, compared with the traditional north-finding method, the proposed methods with the optimized step angles and the symmetric step angles can reduce the north-finding errors by 67.5% and 62.5%, respectively. The method with symmetric step angles is not affected by the azimuth angles and can offer consistent high accuracy for any azimuth angles.

Infulence of Chemical Composition and Metallographic Structure to Dimagnetic Stainless Steel

A kind of rotating step motor is used in special environment, which has the character of single step angle great,single step rotating speed rangeing widely and output turque rangeing widely. To adapt the using environment and its working characteristics, the motor’s main parts of shell and front-backcovers are all made up of the stainless steel 1Cr18Ni9Ti, which has a good performance in diamagnetic and comperhensive mechanics. During the manufacture process, the 1Cr18Ni9Ti was found can be absorded by magnet. This paper researchs the influence of elements components and metallographic structure to the 1Cr18Ni9Ti by analyzing the element components and metallographic structure of several batches of materials.

Long-range surface faceting induced by chemisorption of PTCDA on stepped Ag(111) surfaces

The organic molecule PTCDA preferentially adsorbs on steps of vicinal Ag(111) surfaces and bunches them to well defined facet planes. These depend on coverage and annealing temperature and are independent of the nominal step direction and angle of inclination of the unreconstructed initial surface. We study the development of the facets and present a map of all 16 types of facets in a stereographic triangle of 35° off the [111]-direction. The faceting mechanism is interpreted as orientational phase separation originating from different bonding strengths of PTCDA on various facets. The faceting drives the system to the minimum of its surface free energy.

Burr height and hole diameter error minimization in drilling of AL6063/15%/SiC composites using HSS step drills

In drilling process, burr plays an important role on the quality parts. It is necessary to minimize the burr height. This paper presents the effect of CNC drilling process parameters like cutting speed, feed rate, step angle and cutting environment on burr height and hole diameter error of Al6063/15%/SiC composites. The composites are fabricated using mechanical stir casting. An experimental study on composites was conducted using three HSS drills. The Taguchi design of experiments and analysis of variance (ANOVA) are used to optimize the response for Al6063/15%/SiC composites. The results revealed that the quality of the holes can be improved by proper selection of cutting process parameters. SEM analysis and XRD analysis are also carried for composite, drilled surface and drill bits. These analysis provide the good agreement with the effect of cutting parameters on burr height and hole diameter error.

Обробка корінця книжкового блока різцями, що закріплені на гнучкій ланці

The chart of device is offered for spinesprocessing, that provides causing on the spine of cross notches by means of cutters at the perfect binding. Cutters are attached to branches of chain transfer. Technical decisions used in devices give an opportunity of causing on the spine of notch with different step and inclinationanglerelatively to the direction of the book block moving. It is set, that decisive influenceon character of treatment surface of spine is presented by speed cutters and their step, installation angle branches of chaintransfer, speed of book block. Analytical dependences to determine the necessary step cuts and angle of inclination, depending on the design parameters of the device and technological process parameters.

Analysis of gait in rats with olivocerebellar lesions and ability of the nicotinic acetylcholine receptor agonist varenicline to attenuate impairments

Studies have demonstrated that administration of the neuronal nicotinic receptor agonist varenicline to rats with olivocerebellar lesions attenuates balance deficits on a rotorod and balance beam, but the effects of this drug on gait deficits have not been investigated. To accomplish this, male Sprague–Dawley rats were trained to walk on a motorized treadmill at 25 and 35cm/s and baseline performance determined; both temporal and spatial gait parameters were analyzed. A principal component analysis (PCA) was used to identify the key components of gait, and the cumulative gait index (CGI) was calculated, representing deviations from prototypical gait patterns. Subsequently, animals either remained as non-lesioned controls or received injections of 3-acetylpyridine (3-AP)/nicotinamide to destroy the climbing fibers innervating Purkinje cells. The gait of the non-lesioned group was assessed weekly to monitor changes in the normal population, while the gait of the lesioned group was assessed 1week following 3-AP administration, and weekly following the daily administration of saline or varenicline (0.3, 1.0, or 3.0mg free base/kg) for 2 weeks. Non-lesioned animals exhibited a 60–70% increased CGI over time due to increases in temporal gait measures, whereas lesioned animals exhibited a nearly 3-fold increased CGI as a consequence of increases in spatial measures. Following 2 weeks of treatment with the highest dose of varenicline (3.0mg free base/kg), the swing duration of lesioned animals normalized, and stride duration, stride length and step angle in this population did not differ from the non-lesioned population. Thus, varenicline enabled animals to compensate for their impairments and rectify the timing of the gait cycle.

Hamming-distance-based adaptive quantum-inspired evolutionary algorithm for network coding resources optimization

An adaptive quantum-inspired evolutionary algorithm based on Hamming distance (HD-QEA) was presented to optimize the network coding resources in multicast networks. In the HD-QEA, the diversity among individuals was taken into consideration, and a suitable rotation angle step (RAS) was assigned to each individual according to the Hamming distance. Performance comparisons were conducted among the HD-QEA, a basic quantum-inspired evolutionary algorithm (QEA) and an individual's fitness based adaptive QEA. A solid demonstration was provided that the proposed HD-QEA is better than the other two algorithms in terms of the convergence speed and the global optimization capability when they are employed to optimize the network coding resources in multicast networks.

Gait Analysis in Cervical Spondylotic Myelopathy.

Study DesignGait analysis of patients with cervical spondylotic myelopathy (CSM) by using a sheet-type gait analysis system.PurposeThe aim of this study was to compare the gait patterns of patients with CSM, evaluated by the Nurick grades, and to determine the threshold values of gait parameters predicting the occurrence of a fall by using a gait recorder.Overview of LiteratureGait disorder due to CSM may progress to severe paraplegia, following even a minor trauma such as a fall. The indications for the surgery of CSM without severe paralysis remain controversial. The quantitative gait analysis and the decision for decompressive surgery in patients with CSM are important in order to prevent severe paraplegia from a fall.MethodsOne hundred thirty-two subjects (normal, 34; CSM, 98) underwent gait analysis by using a sensor sheet. Measurements of gait cycle parameters included the step and stride length, step width, foot angle, swing phase, and stance phase. CSM was assessed by Nurick grade.ResultsAlthough the clinical symptoms were lacking, Nurick grade 1 had significant abnormalities in the parameters of velocity, step length, and step angle (p<0.05). Regarding the Nurick grade and walking phase, the length of the stance phase was increased to more than 70% of the entire walking cycle in Nurick grade 4.ConclusionsGait analysis was an objective tool for evaluating the gait stability. Our results suggested that when the percentage of the stance phase in the gait cycle increases to above 70%, the CSM patients have an increased fall risk.

3-D Wideband Antenna for Head-Imaging System with Performance Verification in Brain Tumor Detection

A 3-D slot-rotated antenna for a microwave head- imaging system is presented. The antenna is designed to have a wideband and unidirectional performance at the low microwave frequency band that are the requirements of the specified imaging system. Starting from a traditional wide-slot antenna, several conventional techniques are applied to enhance its bandwidth and directivity while miniaturizing its size. In that regard, four series of staircase-shaped slots are applied to lower the operating frequency, whereas a folding process is used to enhance the directivity and reduce the overall size. In addition, two parasitic patches are connected to the slot area to increase the operating bandwidth. The final design has the dimensions of 0.11 λ×0.23 λ×0.05 λ. ( λ is the wavelength of the lowest measured operating frequency.) It has a measured VSWR fractional bandwidth of 87% (1.41-3.57 GHz) and a peak front-to-back ratio of 9 dB. To verify the suitability of the antenna in head imaging, it is connected to a wideband microwave transceiver and used to circularly scan an artificial head phantom in 20 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> angle steps in a monostatic mode. The collected backscattered data are then processed and used to generate an image that successfully shows brain tumors. The compact size, wide operating bandwidth, unidirectional radiation, and detection viability are merits of the presented antenna and the subsequent system.

Review of the design of the helicopter rotor

This article - paper presents the design of the main rotor of the helicopter supported by the patent documents, as a very useful tool (instrument) to reach the specific ideas and design in order to find the most economical way for the quality solution for a certain technical problem present in the process of design (construction). A large amount of technical information first appears in patent documents and about two thirds of this information cannot be found on any other site. The structure of patent documents is presented with an emphasis on the elements that relate to technical information with the detailed explanation of the possibilities of the application of the patent documentation during the process of design of the main helicopter rotor. The procedure and methods of research of the related patent documents are presented on a specific example of helicopter rotor design. The Espacenet database of patent documents was used as the most comprehensive and the most frequently used database containing over eighty million different patent documents about inventions and technical improvement (advancement) from all over the world. The crucial part of the paper relates to the presentation of a patent search method in order to find a technical solution for the structures of the main helicopter rotor which relates to the provision of the required casting and rapid response changes of accommodation angle (step) of the rigid rotor blades of helicopters.

Multi-tracer Imaging of a Compton Camera

Since a Compton camera has high detection sensitivity due to electronic collimation and a good energy resolution, it is a potential imaging system for nuclear medicine. In this study, we investigated the feasibility of a Compton camera for multi-tracer imaging and proposed a rotating Compton camera to satisfy Orlov’s condition for 3D imaging. Two software phantoms of 140 and 511 keV radiation sources were used for Monte-Carlo simulation and then the simulation data were reconstructed by listmode ordered subset expectation maximization to evaluate the capability of multi-tracer imaging in a Compton camera. And the Compton camera rotating around the object was proposed and tested with different rotation angle steps for improving the limited coverage of the fixed conventional Compton camera over the field-of-view in terms of histogram of angles in spherical coordinates. The simulation data showed the separate 140 and 511 keV images from simultaneous multi-tracer detection in both 2D and 3D imaging and the number of valid projection li nes on the conical surfaces was inversely proportional to the decrease of rotation angle. Considering computation load and proper number of projection lines on the conical surface, the rotation angle of 30 degree was sufficient for 3D imaging of the Compton camera in terms of 26 min of computation time and 5 million of detected event number and the increased detection time can be solved with multiple Compton camera system. The Compton camera proposed in this study can be effective system for multi-tracer imaging and is a potential system for development of various disease diagnosis and therapy approaches.

A New Steering-by-Wire System Driving by Electric Wheels

For electric power steering is weak and can not be used in heavy vehicles. In order to solve this problem, according to the characteristic that the driving torque of left and right steering wheel can be independently controlled in electric wheel driving vehicle, a new non-trapezium-steering system has been proposed based on electric wheel driving and powering in this paper. This system makes use of the steering torque around the kingpin from electric wheel driving, and is controlled by steering constraint mechanism. Steering system force analysis was conducted to analyze the feasibility of the system in theory. On this basis, a small prototype vehicle was designed. With the use of Bluetooth wireless serial chip and STC12c5a60s2 microcontrollers, the steering-by-wire system lower computer was developed. With the LabView software, the upper computer system was developed in notebook computer. With these two systems, the steering system can conduct data acquisition and control. To verify the performance of the system, the steering angle step input test while vehicle is stationary, the steering angle step input test at low running speed were carried out respectively on the prototype vehicle. Results of steering wheel turning angle and wheel rotation rate show that non-trapezium steering-by-wire electric wheel driving power system can complete steering operation in a variety of conditions, and after removing steering trapezium, each wheel can be separately controlled for steering, and easy to implement multi-mode steering.