Rotational Part Research Articles

Laser-Induced Fluorescence Spectroscopy of Large Secondary Alkoxy Radicals: Part II. Rotational and Fine Structure.

Selected vibronic bands of the B̃ ← X̃ laser-induced fluorescence (LIF) spectra of jet-cooled 2-pentoxy and 2-hexoxy, including the origin and CO-stretch bands, have been measured with rotational resolution and analyzed using (1) an effective Hamiltonian that comprises a rotational part and a spin-rotation (SR) part (the "isolated-states model") and (2) a recently developed Hamiltonian in which the nearly degenerate à and X̃ states are treated together (the "coupled-states model") (see Liu, J., J. Chem. Phys. 2018, 148, 124112). The observed rotational and fine structures of the strongest vibronic bands have first been simulated using a genetic algorithm with the isolated-states model. The parameters for the simulation include rotational constants for both the X̃ and B̃ states, which can be calculated from the electronic structure theory, as well as the electronic SR constants of the X̃ state and the transition dipole moments (TDMs), both of which are predicted based on their transferability in an "orbital-fixed coordinate system" using iso-propoxy as the reference molecule. Quantum chemistry calculations suggest that the lowest two electronic (X̃ and Ã) states of secondary alkoxy radicals have small energy separations on the order of 100 cm-1 (see Part I of this series: J. Phys. Chem. A 2021, DOI: 10.1021/acs.jpca.0c10662). The electron configurations of these two nearly degenerate states have been determined by comparing the experimentally determined rotational constants and the TDMs to the ones predicted for the X̃ and à states. The experimental LIF spectra were also simulated with the coupled-states model, in which the effective spin-orbit (SO) constants (aζed) and the SO-free separation between the à and the X̃ states (ΔE0) have been determined. Molecular constants derived from fitting the rotational and fine structures of the experimental LIF spectra enabled unambiguous assignment of the observed vibronic bands to specific conformers of 2-pentoxy and 2-hexoxy as reported in Part I.

Large time existence of Euler–Korteweg equations and two-fluid Euler–Maxwell equations with vorticity

The aim of this paper is to study the influence of the vorticity on the existence time in fluid systems for which global smoothness and decay are known in the case of small irrotational data. We focus on two examples: the Euler–Korteweg system and the two-fluid Euler–Maxwell system. We prove that the lower bound of the lifespan of these systems is no less than the inverse of the Hs(s>5∕2) norm of the rotational part of the initial velocity. Our approach is based on energy estimates and the fast time decay results of global solutions to these systems with irrotational initial data.

5.4: An active approach of TFT matrix controlling for liquid crystal cladding based beam steering device

Currently, Light Detection and Ranging (LiDAR) system has been widely used in various applications. However, the commercialized solution can hardly meet the rising demands, especially in autonomous driving vehicles. To further improve the laser scanning rate, life‐time and possibly lowering the cost, the main technology trend is through replacing the mechanical rotational parts with solid structures. Among those new emerging technology approaches, liquid‐crystal‐based beam steering device is one of the promising routes. In this work, for the first time in reports, the physics of such liquid‐crystal‐based devices are thoroughly explained through numerical simulation and modeling. In addition, a new device architecture with thin film transistors (TFTs) matrix and its driving methods are also introduced. With the improved driving electrodes (using TFTs panel), a wide beam steering angle (±42°) can be achieved. Meanwhile, the device remains as a reprogrammable piece even after fabrication, leaving enough room for further upgrades in terms of driving algorithm.

A Whole New World: A Medical Student's Reflection on the Moments Before Surgery for Breast Cancer.

Medical school clerkship offers third year medical students multiple opportunities to acquire clinical experience through real patient interactions and integration into the healthcare teams of different specialties. As part of the general surgery rotation, medical students are invited to scrub in to assist with surgeries-a chance to simultaneously gain medical knowledge while developing technical skills. In what is often an impersonal experience for most patients, students are encouraged to consider the patient's perspective throughout their surgical journey from the pre-operative to post-operative stages. In this reflection, a third year medical student discusses her experience on the moments before breast surgery. From the point of view of a breast cancer patient, she reflects on the impact of a mastectomy on a patient's identity and comments on the importance of empathy in helping a patient grapple with their unique illness experience.

Automatic Feature Recognition of Cross Holes in Hollow Cylinders

Automatic Feature Recognition (AFR) techniques provide the capabilities for translating the data of the part definition between Computer Aided Design (CAD) system and the feature needed to be determined; these techniques take a general CAD model, which is commercially available for providing an automated interface to extract and recognize the manufacturing features from the CAD model. Standard for Exchange of Product (STEP) format is an international standard for transporting geometric and non-geometric data between CAD and Computer Aided Manufacturing systems. Many researches have investigated the AFR in symmetrical features in rotational parts, but few studies have tried to recognize the cross-hole feature because of the recognition difficulty of such feature. A cross hole is recognized with existence of (B-spline Curve with Knots) string in (STEP AP203) neutral file. Cross holes might be perpendicular, offset or inclined to cylinder’s axis, it also can be blind or through. Extraction of the necessary information from (STEP) file for generating the parameters of the manufacturing operation becomes a significant task. In this paper, a new approach for automatic recognition of cross hole feature in hollow cylinders is developed, This approach has been built by connecting the Visual Basic programming language (VB) to the SolidWorks software. The drawing is sent to the VB after saving it as a (STEP AP203) file. VB extracts and recognizes the cross-hole feature according to the rule-based reasoning, some case studies for demonstrating the application of this method on different cases of the cross-hole are presented.

Growing winter Brassica carinata as part of a diversified crop rotation for integrated weed management

AbstractBrassica carinata A. Braun is a non‐edible, oilseed winter crop for biofuel production that can diversify crop rotations and improve integrated weed management. The research objective was to evaluate the influence of B. carinata on weed population dynamics in the southeastern United States cropping systems. B. carinata was grown after cotton (Gossypium hirsutum L.), peanut (Arachis hypogea L.), or a clean summer fallow, and winter weed pressure was modified with or without S‐metolachlor. The emergence of Lamium amplexicaule L. increased at least 40% after cotton or peanut in 2018–2019 and 50% after cotton in 2019–2020 compared to summer fallow. Stellaria media (L.) Vill. emergence was increased over threefold after peanut or cotton in 2019–2020. Senna obtusifolia (L.) H.S. Irwin & Barneby emergence after cotton was increased at least 43% during both experimental years, whereas Amaranthus hybridus L. emergence was increased over 50% after peanut in 2019–2020 compared to summer fallow. Even without S‐metolachlor, B. carinata reduced A. hybridus (>27%) and S. obtusifolia (>25%) emergence compared to weedy winter fallow. After B. carinata harvest, A. hybridus emergence was reduced >40% with or without S‐metolachlor compared to winter fallow in 2018–2019. Overall, B. carinata biomass was highest after peanut for both seasons. B. carinata seed yield did not differ among crop history treatments in the first season, whereas in 2019–2020, the yield was higher after peanut (2417 kg ha−1) or fallow (2520 kg ha−1) compared to cotton (1710 kg ha−1). Weed management treatments were not different for B. carinata biomass or yield in any year. The results indicate that B. carinata can enhance integrated weed management strategies at the rotational level for summer crops by reducing seed banks of summer weed species, in addition to its potential as a winter biofuel crop for the southeastern United States.

Rot‐free finite elements for gradient‐enhanced formulations at finite strains

AbstractThis contribution presents a mixed C0 continuous finite element approach for gradient enriched formulations. The approach is based on a split of the Lagrange multiplier into a gradient and a rotational part, through which a decoupled set of variational equations is obtained. Application to numerical examples in the finite strain gradient elasticity framework unveils the reduced computational effort due to the decoupled character of the global system of equations such as the ability to avoid stress localization.

Thermomechanical modeling of nonlinear internal hysteresis due to incomplete phase transformation in pseudoelastic shape memory alloys

This paper presents a thermomechanical model for pseudoelastic shape memory alloys (SMAs) accounting for internal hysteresis effect due to incomplete phase transformation. The model is developed within the finite-strain framework, wherein the deformation gradient is multiplicatively decomposed into thermal dilation, rigid body rotation, elastic and transformation parts. Helmholtz free energy density comprises three components: the reversible thermodynamic process , the irreversible thermodynamic process and the physical constraints of both. In order to capture the multiple internal hysteresis loops in SMA, two internal variables representing the transition points of the forward and reverse phase transformation, $$\phi _s^f$$ and $$\phi _s^r$$ , are introduced to describe the incomplete phase transformation process. Evolution equations of the internal variables are derived and linked to the phase transformation. Numerical implementation of the model features an Euler discretization and a cutting-plane algorithm. After validation of the model against the experimental data, numerical examples are presented, involving a SMA-based vibration system and a crack SMA specimen subjected to partial loading–unloading case. Simulation results well demonstrate the internal hysteresis and free vibration behavior of SMA.

A Robust Multi-State Constraint Optimization-Based Orientation Estimation System for Satcom-on-the-Move

Current orientation estimation system (OES) approaches can meet the Satcom-on-the-move (SOTM) accuracy requirement in low dynamics using inertial measurement unit (IMU) without Global Navigation Satellite System (GNSS). However, the estimation accuracy will decrease significantly due to the influence of the high dynamics of the vehicle. This article addresses this issue by constructing a multi-state constraint optimization-based OES (MSCO-OES). Our first contribution is a high-precision incremental inertial constraint, which adds the influence of the earth's rotation to the rotation part of the pre-integration theory to maintain the integral gyro accuracy for a longer time. The second contribution is that the nonlinear optimization method is applied to orientation estimation, making better use of historical information and having higher estimation accuracy and robustness through batch optimization and iterating. In addition, we use the lie group theory to extend the weighted least square estimation algorithm to the manifold, which can update multiple historical states to the current state in real-time through incremental inertial constraints. Compared with state-of-the-art methods, the proposed orientation estimation method has higher estimation precision and a reasonable calculation amount. The performance of the proposed method is demonstrated by comparing tests and SOTM deploying tests. Several high-dynamic and long-range tests show that the proposed OES has acceptable orientation estimation precision and reliability, which meets the high-reliable SOTM system requirements.

Motion Cueing Control Design Based On A Nonlinear Mpc Algorithm

Abstract This paper deals with the analysis and design of motion cueing algorithms which can be formulated in terms of constrained control problems. Automotive manufacturers using driving simulation for ADAS development need to design their controllers, called Motion Cueing Algorithms (MCA), in order to render the expected feelings to the subjects. Ultimately, the goal is to bring the virtual driving environment to the realism of the driving scenes. Our contribution in the present work is focused on the development of two nonlinear MPC schemes that include the inherent physical constraints but consider also the real-time requirements. The first one privileges the lateral linear movement of the platform while the other focuses on the nonlinear rotational part. The paper summarizes this line of development with a horizon-based design of MCA using the trade-off between computational effort and tracking performance.

Rigid vorticity transport equation and its application to vortical structure evolution analysis in hydro-energy machinery

Vortex is the dominant flow structure in hydro-energy machinery, and its swirling features are mainly determined by the rigid rotation part of vorticity. In this study, the rigid vorticity transport equation is proposed based on the vorticity decomposition. The vortex spatial evolution is described by the stretching term RST, the dilatation term RDT, the Lamb term RCT and the viscous term RVT. The shape change of a vortex tube is mainly affected by RST and RDT, while vortex production and dissipation are mainly reflected by RCT and RVT. Compared with the traditional vorticity transport equation, this new theoretical tool can distinguish between rigid rotation and shearing motion of local fluids, and it can better reveal the intuitive evolution characteristics of vortical structures. Two cases with clear engineering demands are analysed by using the transport equation, and the results show that it can provide a practical method for the analysis and control of vortical flows in hydro-energy machinery.

On [formula omitted] rational motions of degree six

In this paper two methods for constructing a C2 rational spline motion of degree six that interpolates given positions are presented. The first method requires the solution of a global linear system of equations and each rational motion segment depends on all the input data. The matrix of the system that determines the rotational part includes some extra free parameters that influence the motion and can be chosen such that the unique solution is guaranteed. The second method that is presented splits the construction of the spline motion to individual local biarc segments which beside the given positions interpolate also some additional derivative information. For this local method it is essential to use the extra degrees of freedom coming from the equivalence relation in the 3-dimensional projective space as well as the biarc construction in order to reduce the degree of the motion to six. Remaining free parameters that arise in the rotational part are examined in detail and two exceptional cases where the solution does not exist, together with possible remedies, are identified. Different possibilities for the construction of the translational part are proposed too. The theoretical results are substantiated with numerical examples.

Design and control of a novel rotary shape memory alloy actuator for two degree of freedom underwater vectored thruster

Underwater vectored propulsion thruster is normally actuated by a step motor or a hydraulic system. The traditional actuators show an inherent shortcoming in energy consumption per volume, low space utilization and structure complexity. Shape memory alloy (SMA) based actuator is considered as a strong competitor to the traditional one, however high torque output and long movement distance to acquire high control accuracy and wide operating range still remain a big challenge. In this work, we developed an SMA-based underwater vectored thruster consisting of two motion rings and their rotary SMA actuators. Two SMA wires combined with supplementary rotation parts are utilized to drive the rotation of each motion ring. The rotary SMA actuator outputs torque that can change the angular position of underwater thruster, and the maximum angle and the response speed can be reached 38° and 1.6° s−1. The experimental results verify the feasibility of applying the rotary actuator to underwater device. Modeling the SMA rotary actuator system helps understanding the rotary process of underwater vectored thruster. Based on the system model, a control scheme integrated with an anti-windup Proportion Integral Differential (PID) controller is proposed. Its performance is compared with that of the integrating angle feedback without an anti-windup block through the simulation method. With the proposed anti-windup PID controller, the results show that the overshoot can be eliminated and the steady error is decreased to 0.01% and 0.9% at 10° and 25° respectively, reflecting that the anti-windup PID controller significantly improves the system controlling performance.

Design and development of high shear mixers: Fundamentals, applications and recent progress

Dispersion of liquids/particles is a key important requirement in a variety of applications including coatings and paints, cosmetics, healthcare, food, and pharmaceutical processes. In all these industrial processes high intensity of energy is required to overcome the adhesion forces or increasing interfacial surface area per unit volume, which is achieved by high-pressure homogenizers, ultrasonic-assisted devices, and high shear mixers (HSMs). In this paper, HSMs are critically reviewed based on their design and development, and applications (such as dispersion of nanoparticles, emulsification, and mixing) in recent years. HSMs are comprised of rotational (rotor) and stationary (stator) parts with a small gap in between. It is found that there is a significant influence of stator geometry on the uniform size distribution as well as energy dissipation. Though there is extensive work on hydrodynamics and mixing in HSMs are available however, still there is no specific scale-up/down criterion is available for HSMs.

Re-approximated: a Medical Student's Reflection on the Surgical Approach to Cancer Treatment.

Medical school clerkship offers third year medical students multiple opportunities to acquire clinical experience through real patient interactions and integration into the healthcare teams of different specialities. As part of the general surgery rotation, medical students are invited to scrub in to assist with surgeries-a chance to simultaneously gain medical knowledge while developing technical skills. They learn that there is a possibility of inflicting harm to the patient at every step of any surgery; from making the first skin incision to tying up the final suture, the importance of staying alert is emphasized until the patient is transferred out of the operating room in stable condition. However, the obligation of a physician to do no harm extends beyond the surgery. In this reflection, a third year medical student discusses her experience during an hours-long Whipple procedure. She reflects on the impact of a cancer diagnosis on a patient's identity and narrative and comments on the necessity of maintaining a balance between offering medical guidance to patients and offering the space for them to express their unique illness experience.

A parameterized automatic programming solution for composite grinding based on digital image processing

In this paper, a parameterized automatic programming solution whose advantage depends on the automatic feature recognition of digital image is proposed and applied to the development of automatic programming software for composite grinding. This solution can overcome the difficulty of recognizing intersecting feature of complicated rotational part. And a 7-layer CNN classifier is utilized to decide whether the part has the internal features or not, which makes the proposed feature recognition method more intelligent than retrieving the unknown objects blindly. The emphasis of the research is the geometric data extraction algorithm which is the synthesis of border following algorithm, corner detection algorithm and a variety of morphological processing. Under the condition of 12000 × 12000 pixel dimension and 200-dpi resolution of input image, the relative errors between the extracted and actual values of various geometric data are all less than 0.05% for the rotational parts of maximum diameter 500 mm and maximum length of 1500 mm. And all the extracted values of geometric data rounded to integers can fully meet the requirements of NC programming. The automatic programming software based on the proposed solution has excellent portability and practicability, which is independent of any CAD tools or data exchange standards. After the programs generated by the automatic programming software are validated in simulation software NCSIMUL, the software is integrated into HNC-848 CNC system and applied in the prototype of H377 composite grinding center.

Estimating the power spectrum of a discrete cosmic momentum field with fast Fourier transform

Fast Fourier transform based estimators are formulated for measuring momentum power spectra, including the auto power spectra of the momentum, the momentum divergence, and the cross spectrum of density fluctuation and momentum divergence. Algorithms using the third order Bettle-Lemarié scaling function to assign discrete objects to regular grids for fast Fourier transform are proposed to clean alias effects. Numerical experiments prove that the implementation can achieve sub-percent precision till close to the Nyquist frequency. The impact of removing bulk flow on the estimation of momentum power spectra is derived theoretically and verified numerically. Subtracting bulk flow has little effects at large scales but might induce meaningful differences in nonlinear regime, and probably it is not necessary to subtract bulk flow for samples which peculiar velocities are exact or sufficiently accurate. Momentum power spectra of dark matter samples fromN-body simulation aremeasured and discussed. As expected, the prediction of the one loop Eulerian perturbation theory agrees with simulation only slightly better than the linear theory at z = 0, but can be applied to higher redshift with improved accuracy. Measurements of simulation data and the one loop Eulerian theory both reveal that the momentum field contains strong rotational part, and there is a large stochastic component in the divergence of momentum which is not correlated with the density field. The three kinds of momentum power spectra have their own characteristics.

Extraction of Doppler signature of micro‐to‐macro rotations/motions using continuous wave radar‐assisted measurement system

Mechanical–structural vibration and/or rotational parts of the targets will induce micro-Doppler frequency in addition to the main Doppler components. In the today's military era, detections, measurements and decision making have to be made after the thorough analysis of main and micro-Doppler signatures of the targets to get their full profile particularly for defence applications. In addition, few of the low radar cross-section targets can be detected only by extracting and processing the micro-Doppler signatures corresponding to the rotations of their propellant rotor blades. Therefore, experimental studies to measure the micro-to-macro rotation/motion generated Doppler frequency and performing its associated measurements become significant. The authors built a C-band (5.3 GHz) continuous wave radar and used it to measure the Doppler frequency generated by micro-to-macro rotations/motions. The detection and measurement accuracy of the developed radar is assessed by series of different open-environment experimental case studies: revolution per minute measurement of rotating blades, separation of multiple rotating blades, oscillation per minute measurement of a swinging pendulum, detection of approaching/receding motion and the Doppler signature extraction of walking/jogging/cycling person. All these measurement values are validated against the standard master instrument readings and theoretical calculations. Finally, the limitations of this system and required near-future research works to enhance its performance are listed.

Three-dimensional viscous Rayleigh-Taylor instability at the cylindrical interface

In this paper, the rotational part of the disturbance flow field caused by viscous Rayleigh-Taylor instability (RTI) at the cylindrical interface is considered, and the most unstable mode is revealed to be three-dimensional for interfaces of small radii R. With an increase in R, the azimuthal wave number of the most unstable mode increases step by step, and the corresponding axial wave number increases as well at each step of the azimuthal wave number. When the amplitude of the wave-number vector is much larger or much smaller than 1/R, the cylindrical RTI is close to the semi-infinite planar viscous RTI limit or the finite-thickness creeping-flow RTI limit, respectively. The effect of the viscosity ratio is double-edged; it may enhance or suppress the cylindrical RTI, depending on R and the amplitude range of the wave-number vector.

Bioinspired Hydrogels with Muscle-Like Structure for AIEgen-Guided Selective Self-Healing

Living systems, including human beings, animals, and plants, display the power to self-heal spontaneously after being damaged. The self-healing is usually selective, which means that the healing ef...