Kinematic Research Articles

Spectroscopy of Galaxies: Evolution of Escape Fractions, Metallicity Gradients and Stellar Metallicity

We use spectroscopic observations to investigate galaxies from the age of reionization to the peak of star formation, and the local universe. This thesis presents three projects to better understand characteristics of galactic feedback, i.e., how it regulates galactic gas flows. We used deep absorption line spectroscopy to estimate the escape fractions fesc of star-forming gravitationally-lensed galaxies at z ≃ 5. The approach is to measure the covering fraction of neutral hydrogen in a galaxy from the amount of non-ionizing UV radiation absorbed by low-ionization metal species. With the boost of signal by gravitational lensing, we observed four 4 Spatially resolved spectroscopic observations of galaxies at the peak era of star-formation activities are effective in providing insight into the primitive disks. Specifically, we used metallicity gradients to provide constraints on the amount and extent of feedback produced in star-forming galaxies. We observed 15 star-forming galaxies at z ~ 2 with OSIRIS to obtain their kinematic properties and gas-phase metallicity gradients. With helps from AO correction and gravitational lensing, the typical spatial resolution in our study is less than a half-light radius of a typical L* galaxies at z ≃ 2. Combining with the sample in Jones et al., 2013, we approximately tripled the existing metallicity gradient measurements. We found a lower fraction of rotationally-supported systems than reported from larger kinematic surveys with coarser spatial resolution, which might be partially due to a our improved spatial resolution. We demonstrated that a high spatial resolution is crucial for an accurate diagnosis of the kinematic properties and dynamical maturity of z ≃ 2 galaxies. As for metallicity gradients, we found a much higher fraction of z ≃ 2 galaxies having weak or flat metallicity gradients than in previous studies. We correlated the metallicity gradient with the total metallicity and found that all galaxies with low total metallicities have flat gradients ( 0.1), there is a divergence between isolated or rotationally-supported and dynamically-immature systems with the latter showing zero gradients irrespective of the integrated metallicity. The results indicate that relatively strong feedback (e.g. high mass loading factors or high SN energy output) is required in order to explain the majority of the observed flat gradients. In the second part of the thesis, we observed quiescent galaxies at z Lastly, we measured magnesium (Mg) abundances and extended the observed redshift to z ~ 0.55. We found that while the mass-[Fe/H] relation evolves significantly over the observed redshift range, the mass-[Mg/H] relation does not. This is due to the shorter star formation histories of quiescent galaxies at higher redshifts. Fe is mainly produced in Type Ia SN. It has a longer recycling time than Mg, which is mainly produced in core-collapse SN. Using core-collapse SN elements as a metal indicator lessens the complication of delayed recycling time and allows us to effectively use galactic chemical models with instantaneous recycling to quantify average outflows that these galaxies experience over their lifetime. We found that the average mass-loading factor η is a power-law function of galaxy stellar mass, η ∝ M*-0.21±0.09, consistent with the results of other observational methods and with the predictions where outflow is caused by star formation feedback in turbulent disks.

Kinematic Analysis on Dotumse Movement of Korean Dance in Accordance with Respiratory Proficiency

Kinematic Analysis on Dotumse Movement of Korean Dance in Accordance with Respiratory Proficiency

A simple HSDT for bending, buckling and dynamic behavior oflaminated composite plates

In the present article, cross ply laminated composite plates are considered and a simple sinusoidal shear deformation model is tested for analyzing their flexural, stability and dynamic behaviors. The model contains only four unknown variables that are five in the first order shear deformation theory (FSDT) or other higher order models. The in-plane kinematic utilizes undetermined integral terms to quantitatively express the shear deformation influence. In the proposed theory, the conditions of zero shear stress are respected at bottom and top faces of plates without considering the shear correction coefficient. Equations of motion according to the proposed formulation are deduced by employing the virtual work principle in its dynamic version. The analytical solution is determined via double trigonometric series proposed by Navier. The stresses, displacements, natural frequencies and critical buckling forces computed using present method are compared with other published data where a good agreement between results is demonstrated.

New 3D failure analysis of water-filled karst cave beneath deep tunnel

In this study, both 2D and 3D failure shapes of rock mass above the water-filled cavity are put forward when the surrounding rock mass cannot bear the pressure caused by the water-filled cavity. Based on the analytical expressions derived by kinematic approach, the profiles of active and passive failure patterns are plotted. The sensitivity analysis is conducted to explore the influences of different rock parameters on the failure profiles. During the excavation of the deep tunnels above the karst cavity, the water table always changes because of progressive failure of cavity roof. Therefore, it is meaningful to discuss the effects of varying water level on the failure patterns of horizontal rock layers. The changing laws of the scope of the failure pattern obtained in this work show good consistency with the fact, which could be used to provide a guide in engineering.

Thermomechanical bending study for functionally graded sandwich plates using a simple quasi-3D shear deformation theory

In this article, a simple quasi-3D shear deformation theory is employed for thermo-mechanical bending analysis of functionally graded material (FGM) sandwich plates. The displacement field is defined using only 5 variables as the first order shear deformation theory (FSDT). Unlike the other high order shear deformation theories (HSDTs), the present formulation considers a new kinematic which includes undetermined integral variables. The governing equations are determined based on the principle of virtual work and then they are solved via Navier method. Analytical solutions are proposed to provide the deflections and stresses of simply supported FGM sandwich structures. Comparative examples are presented to demonstrate the accuracy of the present theory. The effects of gradient index, geometrical parameters and thermal load on thermo-mechanical bending response of the FG sandwich plates are examined.

Kinematics and Structural Analysis for 5ton cargo-truck Elecrto-Hydraulic Sliding Deck Systems Manufacturing and Design of winch system for safety

Kinematics and Structural Analysis for 5ton cargo-truck Elecrto-Hydraulic Sliding Deck Systems Manufacturing and Design of winch system for safety

Capability evaluation of self-location machining algorithm for ultra-precision workpiece based on SVD

In order to further improve the final precision, efficiency and cost-effectiveness of ultra-precision surface modification, and optimize the process direction and process decision-making of ultra-precision self-positioning processing, this paper studies the point cloud fusion process of self-positioning processing algorithm for ultra-precision workpieces. Based on the evaluation, it proposes a self-positioning processing algorithm capability evaluation method based on SVD. Firstly, based on the kinematics method, the matrix representation of point cloud fusion is established. The transformation matrix representation of self-positioning results is established for the translation, rotation and compound motion, respectively. Then the self-positioning point cloud fusion transformation matrix is obtained. A singular value decomposition is performed to obtain a singular value list of the transformation matrix. finally, the largest singular value in the list is used to characterize the self-positioning processing algorithm. By analyzing the free-precision states of a certain type of ultra-precision blade (a total of 1078 sets of free-standing state) it is found that the proposed evaluation index can correctly characterize self-positioning under the condition of independent translation and independent rotation. For the independent translation, the self-positioning processing algorithm can be positioned normally, and the maximum singular deviation value is also less than the pre-set value. For the independent rotation, when the angle is less than 45°, the self-positioning machining can be correctly performed. The singular value difference also approaches zero. Above 45°, the algorithm's self-positioning machining capability deteriorates, and this feature can be correctly captured by the proposed indicators. For the composite motion consisting of translation and rotation, the proposed index shows that about 35% of the cases can be correctly self-positioned, and the rest can not be correctly self-homing. It indicates that the indicators established by the proposed method can correctly characterize the self-positioning machining algorithm.

Rigid plastic analysis for the seismic performance evaluation of steel storage racks

The aim of the paper is the prediction of the seismic collapse mode of steel storage pallet racks under seismic loads. The attention paid by the researchers on the behaviour of the industrial steel storage pallets racks is increased over the years thanks to their high dead-to-live load ratio. In fact, these structures, generally made by cold-formed thin-walled profiles, present very low structural costs but can support large and expensive loads. The paper presents a prediction of the seismic collapse modes of multi-storey racks. The analysis of the possible collapse modes has been made by an approach based on the kinematic theorem of plastic collapse extended to the second order effects by means of the concept of collapse mechanism equilibrium curve. In this way, the dissipative behaviour of racks is determined with a simpler method than the pushover analysis. Parametric analyses have been performed on 24 racks, differing for the geometric layout and cross-section of the components, designed in according to the EN16618 and EN15512 requirements. The obtained results have highlighted that, in all the considered cases, the global collapse mechanism, that is the safest one, never develops, leading to a dangerous situation that must be avoided to preserve the structure during a seismic event. Although the studied racks follow all the codes prescriptions, the development of a dissipative collapse mechanism is not achieved. In addition, also the variability of load distribution has been considered, reflecting the different pallet positions assumed during the in-service life of the racks, to point out its influence on the collapse mechanism. The information carried out from the paper can be very useful for designers and manufacturers because it allows to better understand the racks behaviour in seismic load condition.

A simple quasi-3D HSDT for the dynamics analysis of FG thick plate on elastic foundation

This work presents a dynamic investigation of functionally graded (FG) plates resting on elastic foundation using a simple quasi-3D higher shear deformation theory (quasi-3D HSDT) in which the stretching effect is considered. The culmination of this theory is that in addition to taking into account the effect of thickness extension (ez ≠ 0), the kinematic is defined with only 4 unknowns, which is even lower than the first order shear deformation theory (FSDT). The elastic foundation is included in the formulation using the Pasternak mathematical model. The governing equations are deduced through the Hamilton's principle. These equations are then solved via closed-type solutions of the Navier type. The fundamental frequencies are predicted by solving the eigenvalue problem. The degree of accuracy of present solutions can be shown by comparing it to the 3D solution and other closed-form solutions available in the literature.

Kinematic Analysis of Drag Flick Shooting Motion for Training Shooters Specializing in Penalty Corners in Women's Field Hockey: A Case Study

Kinematic Analysis of Drag Flick Shooting Motion for Training Shooters Specializing in Penalty Corners in Women's Field Hockey: A Case Study

Nonlinear analysis of viscoelastic micro-composite beam with geometrical imperfection using FEM: MSGT electro-magneto-elastic bending, buckling and vibration solutions

In this research, the nonlinear static, buckling and vibration analysis of viscoelastic micro-composite beam reinforced by various distributions of boron nitrid nanotube (BNNT) with initial geometrical imperfection by modified strain gradient theory (MSGT) using finite element method (FEM) are presented. The various distributions of BNNT are considered as UD, FG-V and FG-X and also, the extended rule of mixture is used to estimate the properties of micro-composite beam. The components of stress are dependent to mechanical, electrical and thermal terms and calculated using piezoelasticity theory. Then, the kinematic equations of micro-composite beam using the displacement fields are obtained. The governing equations of motion are derived using energy method and Hamilton\'s principle based on MSGT. Then, using FEM, these equations are solved. Finally the effects of different parameters such as initial geometrical imperfection, various distributions of nanotube, damping coefficient, piezoelectric constant, slenderness ratio, Winkler spring constant, Pasternak shear constant, various boundary conditions and three material length scale parameters on the behavior of nonlinear static, buckling and vibration of micro-composite beam are investigated. The results indicate that with an increase in the geometrical imperfection parameter, the stiffness of micro-composite beam increases and thus the non-dimensional nonlinear frequency of the micro structure reduces gradually.

Size-dependent plastic buckling behavior of micro-beam structures by using conventional mechanism-based strain gradient plasticity

Since the actuators with small- scale structures may be exposed to external reciprocal actions lead to create undesirable loads causing instability, the buckling behaviors of them are interested to make reliable or accurate actions. Therefore, the purpose of this paper is to analyze plastic buckling behavior of the micro beam structures by adopting a Conventional Mechanism-based Strain Gradient plasticity (CMSG) theory. The effect of length scale on critical force is considered for three types of boundary conditions, i.e. the simply supported, cantilever and clamped - simply supported micro beams. For each case, the stability equations of the buckling are calculated to obtain related critical forces. The constitutive equation involves work hardening phenomenon through defining an index of multiple plastic hardening exponent. In addition, the Euler-Bernoulli hypothesis is used for kinematic of deflection. Corresponding to each length scale and index of the plastic work hardening, the critical forces are determined to compare them together.

Depth Resolution Enhancement in Time-of-Flight Cameras Using Polarization State of the Reflected Light

Time-of-Flight (ToF) cameras are nowadays commonly used for depth measurements and are useful in applications, such as robotic navigation, gaming, and others. The depth measurements by the ToF camera are influenced by the systematic errors of the camera and the nonsystematic errors of the environment. This paper presents a novel method for reduction of depth measurement error using polarization state of the reflected light. Using polarization state of the reflected light, the nonsystematic errors introduced due to multipath interference, material properties, and color of the target object reduces, which reduces the depth errors. The idea is tested using SR-4000 3-D sensor and a linear polarizer in front of it. The transmission angle of the linear polarizer is varied for a fixed object distance from the camera. The depth error has a sinusoidal variation with clear maxima and minima. It is observed that the depth error is minimum when the polarization angle is equal to the ToF phase shift. The experimental results show a maximum of 87% reduction in depth error at 3000 mm distance using polarization angle equal to ToF phase shift. The reduction in the nonsystematic error in the ToF-based distance measurements using polarization of the reflected light will enable new applications, such as diffuser imaging, detection of transparent objects, and among others.

Kinematics Conceptual Understanding: Interpretation of Position Equations as a Function of Time

Abstract : This article aims at describing the ability of 48 students of physics education in determining the distance traveled, average speed, and acceleration of position functions. To achieve these objectives, three reasoned multiple choice questions were used. The question is part of 20 standard test questions that are used to measure understanding of student mechanics concepts in the Basic Physics course. The study was conducted using a survey method. Data were obtained from student responses in answering questions. Claims of student understanding were seen from the choice of answer options and reasons given. The results of the study indicate that students still have many wrong assumptions regarding x(t), namely as a displacement; determine the distance from x(t) by adding the position of each unit of time and adding the initial and final positions; and assume that acceleration (-) is slowing down. Key Words : conceptual understanding, function of position, kinematics Abstrak : Artikel ini bertujuan untuk mendeskripsikan kemampuan 48 mahasiswa pendidikan fisika dalam menentukan jarak tempuh, kecepatan rata-rata, dan percepatan dari fungsi posisi. Untuk mencapai tujuan tersebut digunakan tiga soal pilihan ganda beralasan. Soal tersebut merupakan bagian dari 20 soal tes standar yang digunakan untuk mengukur pemahaman konsep mekanika mahasiswa pada mata kuliah Fisika Dasar. Penelitian dilakukan dengan menggunakan metode survei. Data diperoleh dari respon mahasiswa dalam menjawab soal. Klaim pemahaman mahasiswa dilihat dari pilihan opsi jawaban dan alasan yang diberikan. Hasil penelitian menunjukkan bahwa mahasiswa masih banyak memiliki anggapan yang salah terhadap x(t) yakni sebagai perpindahan; menentukan jarak tempuh dari x(t) dengan men-jumlah posisi setiap satuan waktu, dan menjumlah posisi awal dan akhir; dan menganggap bahwa percepatan (-) sebagai perlambatan. Kata kunci : pemahaman konsep, fungsi posisi, kinematika

Adaptive turning control for an agricultural robot tractor

An adaptive turning algorithm for a four-wheel robot tractor in the headland is presented in this paper. The navigation sensors consisted of an inertial measurement unit and a real-time kinematic global positioning system (GPS). An objective function based on weights was used to create the navigation path, connecting by continuous primitives. The asymmetric steering mechanism was then taken into consideration with a vehicle model. To follow the path accurately, the slide movement of the robot and the steering rate were taken into account by estimating the turning radius in real time. In addition, the vehicle model was tuned based on the results of each turn. Therefore, the turning control algorithm was optimized on the basis of the specific conditions in the field. Field experiments showed that the robot tractor approached the next path with an average lateral deviation of 3.9 cm at a speed of 1.2 m/s during a turn. Compared to a conventional turning scheme, the time consumption and turning trajectory were decreased by 17% and 21%, respectively. Keywords: autonomous tractor, path planning, dynamic circle-back turning, switch-back turning, robot tractor, reinforcement learning DOI: 10.25165/j.ijabe.20181106.3605 Citation: Wang H, Noguchi N. Adaptive turning control for an agricultural robot tractor. Int J Agric & Biol Eng, 2018; 11(6): 113–119.

Receive Beam-Steering and Clutter Reduction for Imaging the Speed-of-Sound Inside the Carotid Artery

Handheld imaging of the tissue’s speed-of-sound (SoS) is a promising multimodal addition to diagnostic ultrasonography for the examination of tissue composition. Computed ultrasound tomography in echo mode (CUTE) probes the spatial distribution of SoS, conventionally via scanning the tissue under a varying angle of ultrasound transmission, and quantifying—in a spatially resolved way—phase variations of the beamformed echoes. So far, this technique is not applicable to imaging the lumen of vessels, where blood flow and tissue clutter inhibit phase tracking of the blood echoes. With the goal to enable the assessment of atherosclerotic plaque composition inside the carotid artery, we propose two modifications to CUTE: (a) use receive (Rx) beam-steering as opposed to transmit (Tx) beam-steering to increase acquisition speed and to reduce flow-related phase decorrelation, and (b) conduct pairwise subtraction of data obtained from repetitions of the scan sequence, to highlight blood echoes relative to static echo clutter and thus enable the phase tracking of blood echoes. These modifications were tested in a phantom study, where the echogenicity of the vessel lumen was chosen to be similar to the one of the background medium, which allows a direct comparison of SoS images obtained with the different techniques. Our results demonstrate that the combination of Rx-steering with the subtraction technique results in an SoS image of the same quality as obtained with conventional Tx-steering. Together with the improved acquisition speed, this makes the proposed technique a key step towards successful imaging of the SoS inside the carotid artery.

Return to Play After an Anterior Cruciate Ligament Injury: Prioritizing Neurological and Psychological Factors of the Decision-Making Algorithm.

Soccer players recovering from anterior cruciate ligament (ACL) injuries have better options for treatment today than they did 25 years ago. Surgical techniques have improved, and rehabilitation protocols have evolved considerably. Although the rehabilitation community is doing a better job of treating this patient population, the evidence does demonstrate that both re-injury and return- to-play (RTP) rates are still suboptimal. Most protocols focus on normalizing strength and range of motion (ROM) and achieving limb symmetry with soccer-specific movements. While these factors are certainly prerequisites for returning to the field, their inclusion does not provide a complete picture of the athlete's presentation. An additional factor that should be prioritized with this patient population is the central nervous system (CNS). Advanced imaging has shown that peripheral deafferentation does occur with musculoskeletal injuries; this ultimately results in cortical reorganization, which makes movement planning more difficult for the player, since simpler tasks must now be processed at higher levels in the CNS. The evidence also shows that the CNS demonstrates plasticity in these cases, so that through focused neuromotor rehabilitation techniques, it is possible to bring movement planning back down to a sub-cortical level. Cognitive issues may also be a factor in preventing the player from returning. Fear of re-injury and diminished confidence can influence the way the player moves on the field, and diminish ability to demonstrate protective kinematics with all soccer-specific tasks. We believe that an approach incorporating traditional musculoskeletal rehabilitation, CNS neuro-motor training, and consideration for cognitive factors, may define an improved paradigm for treating the soccer player and assessing readiness for RTP following ACL injury.

3D Radiation Pattern Reconfigurable Phased Array for Transmission Angle Sensing in 5G Mobile Communication.

This paper proposes a 3D radiation pattern reconfigurable antenna (RPRA) and a reconfigurable phased array (RPA) for 5G mobile communication. The antenna and array are working at 28 GHz, which is selected as a 5G communication band in many countries. The proposed phased array will be applied as sensors to find out the optimal transmitting–receiving angle in a randomly changed cellular wireless scenarios. The RPRA and RPA are fed by Substrate Integrated Waveguide (SIW) and have three switchable radiation modes: Broadside 1, Broadside 2 and Endfire. The three modes correspond to three different radiation patterns and each of them covers a different area in the Azimuth plane. An eight-element phased array constructed by the proposed RPRA, which is able to switch beam in Azimuth plane and scan in the Elevation plane, is also presented in this paper. The proposed RPA is able to provide much higher spatial coverage than the conventional phased arrays and without additional feeding and phase shifting networks. The beam switching is realized by the PIN diodes. The proposed antenna and array have planer structures and require small clearance on the ground plane which makes them compatible with mobile phones. The simulations show good performance for both RPRA and RPA.

Cyclic behavior of soils and numerical analyses in cold regions and seismic zones

The solutions of boundary value problems involving strain-softening material property contain serious difficulties from both modeling of strain-localization and a viewpoint of numerical procedure. Mesh size-dependent hardening modulus is considered to alleviate the mesh size-dependency of the solution. The elasto-plastic soil model with kinematic hardening model considering the cumulative deformation by cyclic loading is developed. In finite element analyses, the dynamic relaxation method combined with the generalized return-mapping algorithm is applied to the static drained and un-drained tri-axial tests and plane strain tests. The cyclic behavior of retaining wall problems by freeze and thaw in cold regions is also analyzed. Finally the dynamic progressive failure analysis of rockfill dam is carried out.

Kinematics, muscle recruitment patterns and pressure mapping in cycling biomechanics - Recent research findings and practical outcomes.

Objectives: With the increase in popularity of cycling, a properly configured bicycle is essential for maximizing performance and preventing injuries, whilst maintaining comfort. It has been suggested that cyclists train in the same conditions that they would race in, optimizing the muscle coordination patterns used during competition. For this reason, it is important to understand both the bicycle setup and the riders position at different intensities. One of the key measurements conducted during bike-setups is the static or dynamic measurement of knee flexion angle. We previously demonstrated that there is a significant change in knee, ankle, hip and shoulder angle from static to dynamic measurements. This change during cycling may have an effect on the cyclists’ performance, economy and injury risk. Other factors to consider are fatigue and workload intensity, and how these may impact on the riders’ position and muscle recruitment patterns. Comparing pressure load and distribution in various saddle zones, through a range of workloads, may give a better understanding to genital discomfort and optimisation of saddle positioning. Methods: Seventeen well-trained cyclists (Age 31±9years, Mass 75.5±7.5kg PPO 354.0±34.5) were enrolled for the study. Whole body kinematics and EMG patterns were analysed during a steady state cycle at 60% VO2 max, and at 60, 80 and 90% heartrate intensities. Saddle pressure was also recorded at 60, 80 and 90% heartrate intensity. Results: There were no changes in body joint angles nor muscle recruitment patterns during the steady state cycle. There were significant changes in the ankle, knee, elbow, thoracic and lumbar flexion angles with increasing intensity (see Figure 1). There were also significant changes in the EMG patterns of the cyclists for all muscles except Medial Gastrocnemius (see Figure 2). The saddle pressure data demonstrated significant changes in the loaded area and mean force through different areas of the saddle. Conclusion: As previously suggested, compensatory lower limb kinematics occur in order to maintain a given power output. For riders that will be training at these specific intensities it would be beneficial to have their bike setup done taking the kinematic changes into account.