Simple Motion Research Articles

О ЗАДАЧЕ ПРОСТОГО ПРЕСЛЕДОВАНИЯ НА ПРАВИЛЬНОМ ЗВЕЗДНОМ МНОГОУГОЛЬНИКЕ

The article considers the pursuit problem with simple motions in the sense of l-capture on the plane of a stellar compact set. A structure is proposed for constructing piecewise - constant pursuit controls that will ensure the completion of the game in a finite time. An upper bound is obtained for the time of the game to complete the pursuit.

A motion capture system for the study of human manufacturing repetitive motions

This manuscript presents a method for motion capture–based manufacturing time and motion studies. The proposed human motion analytics system uses motion capture technology to collect, transform, store, and analyze data from repetitive physical motions performed by manufacturing workers. The system supports the isolation of basic simple motions for analysis using statistical process control and data analytics techniques. The proposed method has resulted in the ability to identify patterns of repetitive motions and statistically significant deviations from those patterns.

New formulation of the finite depth free surface Green function

For a pulsating free surface source in a three-dimensional finite depth fluid domain, the Green function of the source presented by John [F. John, On the motion of floating bodies II. Simple harmonic motions, Communs. Pure Appl. Math. 3 (1950) 45-101] is superposed as the Rankine source potential, an image source potential and a wave integral in the infinite domain $(0, \infty)$. When the source point together with a field point is on the free surface, John's integral and its gradient are not convergent since the integration $\int^\infty_\kappa$ of the corresponding integrands does not tend to zero in a uniform manner as $\kappa$ tends to $\infty$. Thus evaluation of the Green function is not based on direct integration of the wave integral but is obtained by approximation expansions in earlier investigations. In the present study, five images of the source with respect to the free surface mirror and the water bed mirror in relation to the image method are employed to reformulate the wave integral. Therefore the free surface Green function of the source is decomposed into the Rankine potential, the five image source potentials and a new wave integral, of which the integrand is approximated by a smooth and rapidly decaying function. The gradient of the Green function is further formulated so that the same integration stability with the wave integral is demonstrated. The significance of the present research is that the improved wave integration of the Green function and its gradient becomes convergent. Therefore evaluation of the Green function is obtained through the integration of the integrand in a straightforward manner. The application of the scheme to a floating body or a submerged body motion in regular waves shows that the approximation is sufficiently accurate to compute linear wave loads in practice.

On a Differential Game in a Stochastic System

We study the game problem of approach for a system whose dynamics is described by a stochastic differential equation in a Hilbert space. The main assumption on the equation is that the operator multiplying the system state generates a strongly continuous semigroup (a semigroup of class $$C_{0}$$ ). Solutions of the equation are represented by a stochastic variation of constants formula. Using constraints on the support functionals of sets defined by the behavior of the pursuer and the evader, we obtain conditions for the approach of the system state to a cylindrical terminal set. The results are illustrated with a model example of a simple motion in a Hilbert space with random perturbations. Applications to distributed systems described by stochastic partial differential equations are considered. By taking into account a random external influence, we consider the heat propagation process with controlled distributed heat sources and sinks.

Altruistic and Aggressive Types of Behaviorin a Nonzero-Sum Positional Differential Gameof Three Persons

In this paper, the results of the author’s previous work concerning a nonzero-sum positional differential game of two persons with different types of the players’ behavior are extended to a game of three persons. For simplicity, the paradoxical type of behavior is not used by the players. The notions of altruistic and aggressive behavior types are generalized. As in the two-person game, it is assumed that each player chooses not only a positional strategy but also an indicator program function. The rules for forming controls for each triple of behavior types and the definition of a BT-solution are clarified. An example of a game with the dynamics of simple motion on a plane and a phase constraint is considered. It is assumed that the players can show altruism and aggression towards their partners, and the case of simultaneous aggression from all the players is not excluded. A description of BT-solutions of the game is given.

Control of the Body Orientation by Means of Several Movable Masses

The problem of controlling the orientation of a rigid body by means of several auxiliary point masses moving with respect to a body is considered. The algorithm of reorientation of the body is proposed on the basis of simple motions of these masses. It is shown that the presence of several (more than three) movable masses facilitates considerably the choice of the domains of their possible motions.

FMS-AMS: Secure proximity-based authentication for wireless access in Internet of Things

Proximity-based authentication enables wireless access points (AP) to allow connection only to devices within a certain authentication range. This would be very convenient for allowing network access only to those within a physical boundary. However, an attacker not within the authentication range may deceive the AP into authenticating its proximity by eavesdropping with higher receiver gain and increasing its transmit power. This can be done easily using an amplifier or a directional antenna. To address this challenge, we propose `Fixed MCS SNR (FMS)' filtering scheme based on the intuition that high MCS requires high SNR, and amplifying the received signal strength does not necessarily improve SNR. We experimentally show that this is true in reality, and our real-world evaluation in various environments (14 locations) shows that FMS scheme prevents `amplifier attacks' in all cases. To further counter the false positives of FMS against `directional antenna attacks' (avg. 35.7%), we also propose `Authentication Motion with Signal strength gap (AMS)' filtering scheme which defends against both attacks in all cases at the cost of requiring the user to make a simple motion. FMS or AMS scheme can be selected according to the application requirement to enhance the security of proximity-based authentication in upcoming IoT.

The Design and Calibration of Instrumented Particles for Assessing Water Infrastructure Hazards

The highly dynamical entrainment and transport processes of solids due to geophysical flows is a major challenge studied by water infrastructure engineers and geoscientists alike. A miniaturised instrumented particle that can provide a direct, non-intrusive, low-cost and accessible method compared to traditional approaches for the assessment of coarse sediment particle entrainment is developed, calibrated and tested. The instrumented particle presented here is fitted with inertial microelectromechanical sensors (MEMSs), such as a triaxial accelerometer, a magnetometer and angular displacement sensors, which enable the recording of the particle’s three-dimensional displacement. The sensor logs nine-axis data at a configurable rate of 200–1000 Hz and has a standard mode of deployment time of at least one hour. The data can be obtained and safely stored in an internal memory unit and are downloadable to a PC in an accessible manner and in a usable human-readable state. A plethora of improved design specifications have been implemented herein, including increased frequency, range and resolution of acceleration and gyroscopic sensing. Improvements in terms of power consumption, in comparison to previous designs, ensure longer periods of data logging. The embedded sensors are calibrated using simple physical motions to validate their operation. The uncertainties in the experiments and the sensors’ readings are quantified and an appropriate filter is used for inertial sensor fusion and noise reduction. The instrumented particle is tested under well-controlled lab conditions, where the beginning of the destabilisation of a bed surface in an open channel flow, is showcased. This is demonstrative of the potential that specifically designed and appropriately calibrated instrumented particles have in assessing the initiation and occurrence of water infrastructure hazards.

INVESTIGATION OF UNDERGRADUATE STUDENTS CONCEPTUAL UNDERSTANDING ABOUT SIMPLE HARMONIC MOTION ON MASS-SPRING SYSTEM

Simple Harmonic Motion (SHM) is one of a primary physics topic that underlies other concepts and is closely related to everyday life and technology. It is used to understand the phenomena of mechanical motion, sound, light, and quantum theory, in particular, harmonic oscillators. This study aimed at investigating students conceptual understanding of simple harmonic motion on the mass-spring system. Data collection was made using tests and interviews. The research subjects consisted of 49 students at a university in Jakarta. The instruments used were multiple-choice tasks. The results of the investigation showed that most students have not been able to name the basic concepts of simple harmonic motion, determine the magnitude of the acceleration of objects due to oscillation, and find the scope of the oscillation period. The results show that the average achievement of students is less than 50%. Lack of understanding of student conception is caused by students not being able to relate previous insights (such as Newtons law and Hookes Law) with strategies for solving problems.

Tidal Effect on Groundwater Fluctuations and Saltwater Intrusion in Coastal Heterogeneous Aquifers. (Dept. C. ( Irrigation And Hydraulics ))

Groundwater table and saltwater wedge in coastal areas are commonly affected by tidal waves fluctuations. In this research, for the first time, a two-dimensional numerical model in plan is developed for simulating both the tidal fluctuation of the beach groundwater table and movement of interface between saltwater and freshwater in both coastal confined and unconfined heterogeneous aquifers. The sharp interface philosophy is adopted to simulate dynamics of freshwater flow. Tidal waves are simulated by simple harmonic motions in time. The solution is based on an approach of separating large and small time scales motions of groundwater fluctuations. The proposed model consists of two sub-models. The first one applied Finite Element Method (FEM) to simulate the hydraulic responses of the aquifer in large time scale and it is coupled with Finite Difference Method (FDM), in the second sub-model, to simulate the corresponding ones in small time scale. The model is verified against analytical solutions presented by other previous researchers in case of homogenous aquifer. To simulate the aquifer heterogeneity, unconditional random log-hydraulic conductivity fields are generated to present different hydraulic conductivity realizations for the aquifer under consideration. The application is carried out on both the hypothetical confined aquifer and the real Quaternary unconfined aquifer in El Arish-Rafah area, Egypt. Results show that both the groundwater fluctuation and saltwater intrusion due to tidal waves are affected by the aquifers heterogeneity and the tidal waves effects in confined aquifers are more significant than in unconfined aquifers.

Automated repair of fragmented tracks with 1D CNNs

Multiple object tracking is an important but challenging computer vision problem. The complex motion of objects makes tracking difficult during long periods of object occlusion, and as a result occlusions frequently cause fragmented tracks with gaps. Previous works use linear interpolation to fill in such gaps, a technique which is only able to model simple motion. As a result, tracked bounding box locations can be quite poor in these situations. In this paper, we propose a 1D CNN based solution to filling gaps which models complex motion in a data-driven way. Our proposed solution uses only bounding box coordinates as input, and as such does not incur the computational cost of processing image features directly. We show that our model significantly outperforms linear interpolation on dynamic sports datasets in terms of mean intersection over union between predicted and ground truth bounding boxes.

Relating simple harmonic motion and uniform circular motion with Tracker

In this study, we demonstrate an interesting relationship between simple harmonic motion and uniform circular motion trough a simple experiment. The experiment requires a low cost-easily found materials and free software, Tracker. To represent uniform circular motion, we use a tape that is stick on a fan moving with the constant angular speed. Meanwhile, spring and pendulum motion are used to represent simple harmonic motion. Through Video Tracker analysis, we have shown that the positions (x and y coordinates) of an object undergoes uniform circular motion fit to the sinusoidal function of time, as same as shown in simple harmonic motion. This simple experiment can be used in high school physics course to lead students in developing a conceptual understanding of uniform circular motion with a less mathematical approach.

An autocollimator with sub-microradian sensitivity

We present a simple autocollimator with sub-microradian sensitivity. To demonstrate the capabilities of our autocollimator, we study the simple harmonic motion of a cantilever beam and apply an external force to affect the cantilever's resonant frequency in the context of dynamic force microscopy. Our setup is ideal for the advanced undergraduate instructional laboratory and allows a variety of high-precision, tabletop experiments.

Twisted-and-Coiled Actuators with Free Strokes Enable Soft Robots with Programmable Motions.

Various actuators (e.g., pneumatics, cables, dielectric elastomers, etc.) have been utilized to actuate soft robots. Besides widely used actuators, a relatively new artificial muscle-twisted-and-coiled actuators (TCAs)-is promising for actuating centimeter-scale soft robots because they are low cost, have a large work density, and can be driven by electricity. However, existing works on TCA-actuated soft robots in general can only generate simple bending motion. The reason is that TCAs fabricated with conventional methods have to be preloaded to generate a large contraction, and thus cannot actuate soft robots properly. In this work, an upgraded technique is presented to fabricate TCAs that can deliver 48% free strokes (contraction without preloading). We first compare the static performance of TCAs with free strokes with conventional TCAs, and then characterize how will the fabrication parameters influence the TCAs' stroke and force capability. After that, we demonstrate that such TCAs can actuate centimeter-scale soft robots with programmable motions (gripping, twisting, and three-dimensional bending). Finally, we combine those motions to demonstrate a soft robotic arm that can perform a pick-and-place task. We expect that TCAs with free strokes can enable miniature soft robots with rich three-dimensional motions for both locomotion and manipulation. Because TCAs are electrically driven, we can also potentially develop untethered soft robots by carrying onboard batteries and control circuits.

Modifying angular and polarization selection rules of high-order harmonics by controlling electron trajectories in k-space

Recent advances in generation of strong laser pulses have enabled the acceleration of electrons in solids into regions far away from the band edge. Because nonlinear currents can be generated by laser-driven carriers in the non-parabolic region, tailored laser fields may allow control of optical properties of high-order harmonics (HHs). So far, investigations on laser-induced nonlinear optical phenomena have focused on the simple electron motion induced by linearly or elliptically polarized fields. However, more complex trajectories can be important for development of novel optoelectronic devices. Here, we show that a weak laser field (optical frequency is ω2) applied in a direction orthogonal to a strong main field (ω1) enhances certain HH intensity components of bulk GaSe by a factor of 100. Good agreement between the experiments and calculations shows that manipulation of the electron trajectory allows breaking inversion symmetry of the electronic states felt by the accelerated electrons and leading to a modification of selection rules for frequency-mixing processes of HHs. Owing to our usage of non-integer multiples for ω1 and ω2, it is found that the generation of HHs constitutes a novel way of ultrafast control of light polarization and optical switching.

Thin-film modeling of resting and moving active droplets.

We propose a generic model for thin films and shallow drops of a polar active liquid that have a free surface and are in contact with a solid substrate. The model couples evolution equations for the film height and the local polarization in the form of a gradient dynamics supplemented with active stresses and fluxes. A wetting energy for a partially wetting liquid is incorporated allowing for motion of the liquid-solid-gas contact line. This gives a consistent basis for the description of drops of dense bacterial suspensions or compact aggregates of living cells on solid substrates. As example, we analyze the dynamics of two-dimensional active drops (i.e., ridges) and demonstrate how active forces compete with passive surface forces to shape droplets and drive their motion. In our simple two-dimensional scenario we find that defect structures within the polarization profile drastically influence the shape and motility of active droplets. Thus, we can observe a transition from resting to motile droplets via the elimination of defects in the polarization profile. Furthermore, droplet motility is modulated by strong active stresses. Contractile stresses even lead to topological changes, i.e., drop splitting, which is naturally encoded in the evolution equations.

Needle Transportable Semi-Automatic Hair Follicle Implanter and Image-Based Hair Density Estimation for Advanced Hair Transplantation Surgery

As the number of hair follicles transplanted in a patient is approximately 2000 or more, hair transplantation by a manual implanter requires a considerable amount of time and money and demands a great amount of patience and pain tolerance from both patients and surgeons. In addition, many surgeons frequently experience musculoskeletal disorders owing to the numerous simple repetitive motions of the shoulder and wrist during the procedure. Moreover, the results of the surgery may vary depending on the skill of the surgeon. Although the hair follicle extraction technology has advanced in recent years, the hair follicle transplantation technology still uses a simple hand-held implanter owing to the difficulty of transplanting hair follicles and hair. In this study, a needle transportable semi-automatic hair follicle implanter that can continuously transplant hair follicles is introduced to alleviate the inconvenience of the existing manual implanter. In the developed semi-automatic implanter, a plurality of needles, into which the hair follicles are inserted, are sequentially supplied from the needle supply magazine to the implanter body by the guide groove. The hair follicles in the supplied needles are transplanted to the scalp through the forward and backward movement of the needle gripper and driving motors. The developed implanter can transplant several hair follicles without any replacement, which can shorten surgery time and reduce the fatigue experienced by patients and surgeons. The effectiveness of the proposed implanter was verified through the results of animal and clinical experiments.

Konsep Kesederhanaan Tari Renteng di Desa Saren, Nusa Penida, Klungkung, Bali

The Renteng dance is a group dance that is held and only taken by adult women in Saren Village, Nusa Penida, Klungkung, Bali. This dance movement is multiyear and repetitive, and the presentation, clothing and musical accompaniment is very simple. The simplicity of the form and presentation of Renteng gives rise to the beauty that provides the formalistic aesthetic experience of this dance. However, the form of a formalistic aesthetic experience has not many people understand it. The focus of the problem in this study was how the concept of simplicity in the Renteng dance in Saren village. The research discusses the concept of simplicity in the Renteng dance which can create a formalistic aesthetic experience. The purpose of this research is to obtain a conceptual depiction of this dance based on the simplicity of its shape. This type of research is descriptive-analytic using non-participant observation methods, interviews, and documentation. The results of this study, that the concept of simplicity on the Renteng dance consisted of the simplicity of the element, the simplicity of the structure, and the simplicity of the technique. The conclusion is first, the concept of simplicity of elements or elements on the Renteng dance is the simplicity of the composition of the elements contained in this dance, which includes motion, floor design, and top design, fashion, and musical accompaniment; Second, the concept of the simplicity of the Renteng dance structure is a draft whose application is composed through simple motion and repetitive patterns; Thirdly, the concept of the simplicity of the Renteng dance technique is achieved through simple means with low or uncomplicated complexity making it easy to be extracted.

Using two tier based concept test to analysis profile of student understanding on the concept of simple harmonic motion

The purpose of this study was to analyze students understanding profile about simple harmonic motion conceptual. The subject of this study were eleventh grade student of sciences class in Surakarta2 State Senior High School with 90 students whose registered as student in the 2018/2019 school year. Sampling in this study used random sampling technique. To analyze students understanding profile used instrument of two tier test with 20 item. Instrument consists two level, first level is multiple choice questions and the second level is open ended free response question which is the reason of student’s answer to the first level questions. The result of this study show that 12,9% of students understanding the concept of simple harmonic motion, 16% of students understand in part, 18,2% of students show misconception, 31,5% of students show specific misconception, and 16,5% of students didn’t understand the concept. The highest concept understand was in concept relation of velocity, angular velocity, displacement and acceleration in simple harmonic motion with 41,11%, and the lowest was in definition of simple harmonic motion with 0,74%.

Simple harmonic motion experiments with the accelerometer sensor on a smartphone: Improving the problem solving-ability

The purpose of this study is to discover the improvement in students’ problem solving abilities after learning activities through a simple harmonic motion experiment method using an accelerometer sensor on an smartphone and revealing student responses on it. Pre-experimental research design with one group pretest-posttest design was used in the study. The samples in this study were students of Class X IPA 1 of SMAN 1 Cilimus Kuningan, West Java. Data on the improvement of students’ problem solving abilities were obtained through an essay test while the student’s response data was obtained through the distribution of response questionnaires. The results showed that the problem-solving ability experienced by students increased in the moderate category. Whereas, the results of the responses of students showed that most of the students responded positively to the learning activities of the sensor accelerometer on this smartphone. So, experiment with smartphone has a potential for improving students problem solving skills.