A novel piezoelectric-actuated microgripper simultaneously integrated microassembly force, gripping force and jaw-displacement sensors: design, simulation and experimental investigation

For assembling easy-to-deform and easy-to-broken micropart, accurate acquisition of microassembly force and gripping force during microassembly process while ensuring parallel movement of jaws of microgripper is the key to ensure consistency, accuracy and reliability of microassembly without damage. In addition, simultaneously real-time detection of jaw-displacement of microgripper is also a necessary condition for rapid and accurate microassembly. This paper proposes and realizes a principle of a parallelogram compliant mechanism (PCM) based piezoelectric-actuated microgripper, which simultaneously integrates with microassembly force, gripping force and jaw-displacement sensors for the first time and ensures parallel movement of jaws under no-load and gripping micropart. The major structure of proposed microgripper is a monolithic compliant mechanism (MCM) composed of a primary lever compliant mechanism and three-stage PCM in series. Among them, the third-stage PCM is orthogonal to other two PCM in series. MCM transmits the displacement and force from piezoelectric actuator to jaws while transforming microassembly force, gripping force and jaw-displacement into surface strain of single-notch hinges of PCM with three-stage in series. On this basis, simultaneously sensing microassembly force, gripping force and jaw-displacement is realized by monitoring surface strain of single-notch hinges of three-stage PCM. The sensing equations of the microassembly force, gripping force, and jaw-displacement are established, respectively. A microgripper is manufactured, a microgripper system is realized and the integrated sensors are calibrated. The hysteresis characteristics, creep characteristics and time response are tested experimentally. Two examples of microassembly sub-process are simulated and carried out on the constructed microassembly experimental setup. The theoretical and experimental results show that the designed microgripper can simultaneously acquire the microassembly force, gripping force and jaw-displacement with high sensitivity, linearity and resolution in processes of gripping hohlraum and applying microassembly force to hohlraum while ensuring the parallel movement of the gripping jaws when gripping and not gripping micropart.

The coordination abilities development in female students based on dance exercises

Background and Study Aim. The physical fitness of students is characterized by the level of their abilities development to perform movements of varying complexity. One of the important components in the system of movements is coordination skills. The aim of the study is to identify the level of special and general coordination of students majoring in "Choreography" and provide recommendations for the development of coordination skills in the process of studying modern-jazz dance. Material and Methods. The study involved students of the first and second year of study (n = 10, at the beginning of the study (1 year) age - 17.4 ± 0.7 years) majoring in "Choreography". Tests were used to determine the level of development of general and special coordination skills. The level of coordination readiness at the beginning of training and after three semesters of training was determined. The study was conducted over three semesters (September 2019 - December 2020). Curricula for students’ training do not include the discipline "Physical Education". The development of physical qualities is the task of special subjects in the course of professional training: 16 hours per week. The workload of students in modern-jazz dance was 2 hours a week. Forms of study for a certain period - full-time (70%), online learning (10%), mixed (20%). In September 2019 and in December 2020, the same students passed selected tests. Results. The following significant changes in increasing the coordination level of the abilities were determined: to control temporal and spatial factors of movements; coordination of movements in combination; vestibular stability; musical-rhythmic coordination (p <0.01). The proposed technique assumes that at the first stage of studying modern jazz dance two, three, four centers are coordinated in simultaneous parallel movement. Conclusions. The need to improve the curriculum of modern jazz dance, the introduction of additional courses to the educational program in the major "Choreography". The technical and lexical base of modern jazz dance in combination with special physical training provides opportunities for the coordination skills development in choreographers.

The Impact of Negative Investment List (NIL) Introduction on Investment Decisions of Foreign and Domestic Investors in Indonesia

As an investment intervention policy, NIL is present to grant legal certainty to investors and invite more investment. Its existence has possible impacts on investment decisions. However, the studies of its effect are limited, focusing only on specific NIL versions and sectors. To fill this gap, the present paper investigates the impact of NIL introduction on the investment decisions of foreign and domestic investors in Indonesia by utilizing all NIL versions and business field-level data of the planned investment values from 2005 to 2018. The analysis shows, first, the NIL introduction may generate the investment inflows from both FDI and DDI. Second, there was a parallel movement of crowding-in effect between foreign and national firms responding to the investment opportunities open to both parties. This study suggests that more detailed and transparent information should be provided in the NIL to guarantee its effectiveness.

Analysis of planetary cloud images considering local rotation

&lt;p&gt;Cloud tracking has been used to measure motions of planetary atmospheres remotely without direct observations. Cloud tracking is a method to track the movements of cloud parcels using temporally-continuous cloud images to obtain cloud motion vectors. Since it is considered in most of the cases that clouds move at the same speed and the same direction as the surrounding atmosphere, the wind direction and wind velocity can be obtained by tracking the movement of clouds. This method has been applied to the atmospheres of the planets, such as Venus and Jupiter, where direct observation is difficult as well as that of the Earth's atmosphere.&lt;/p&gt; &lt;p&gt;In the cloud tracking methods developed so far, only the parallel movement of the characteristic pattern is assumed, and the rotation of the pattern is not directly measured. Here we developed a new algorithm to track the parallel movement and the rotation of cloud patterns using the rotation invariant phase-only correlation method. In this method, the tracking region is Fourier-transformed before applying the phase correlation method for measuring parallel movement, and logarithmic polar coordinate conversion is performed to the amplitude spectra so that the rotation and enlargement/reduction motions can be obtained as parallel movements. With this method, not only the parallel movement but also the rotational movement of the characteristic pattern can be detected at the same time.&lt;/p&gt; &lt;p&gt;We first applied the newly-developed method to simulated image pairs. The rotation rate of the cloud pattern and the vorticity derived from the velocity field were compared in three velocity patterns: solid body rotation, irrotational vortex, and sinusoidal velocity field in the latitude and longitude directions. As a result, in the case of a solid body rotation, the wind speed field and the rotation angle were determined correctly. Large-scale rotations can be measured more accurately by the new method than by the calculation of vorticity from the cloud-tracked velocity. When the scale of the velocity structure is decreased, the number of missing cloud tracking vectors increases, and thus the spatial pattern of the vorticity becomes difficult to obtain. Even in such cases, the spatial pattern of the rotation rate can be relatively well retrieved although its amplitude is underestimated.&lt;/p&gt; &lt;p&gt;The new method was applied to Jupiter and Venus images based on the results above. For Jupiter, many small eddies were found to be distributed in the equatorial region. The spatial scales and the strengths of the eddies resemble those seen in numerical simulations. The observed vortex chains can contribute to the formation of Jupiter's equatorial jet. For Venus, though small-scale eddies are less prominent, a planetary-scale distribution of the rotation rate with a north-south reflection symmetry was seen, such that anti-clockwise rotation occurs in the northern hemisphere and clockwise rotation in the southern hemisphere. Since the large-scale rotation pattern is consistent with the latitudinal shear of the mean zonal wind, the result means that the rotation of small-scale clouds is caused by the large-scale wind. This result suggests that the small-scale streaky features at mid-latitudes, whose origin is poorly understood, are created by the deformation of clouds by large-scale winds.&lt;/p&gt; &lt;p&gt;The newly-developed method can extract smaller scale eddies than those observed in the previous studies; the method has enabled investigation of the interaction between different scales in a wider wavelength range. The method would also enable studies of mesoscale weather systems such as deep convection and also studies of upward energy cascade from small-scale convective storms to planetary scale motions in planetary atmospheres.&lt;/p&gt;

Kinematic Error Modeling of Delta 3D Printer

The development of additive manufacturing requires the improvement of 3D printers to increase accuracy and productivity. Delta kinematics 3D printers have advantages over traditional sequential kinematics 3D printers. The main advantage is the high travel speed due to the parallel movement of the platform from three pairs of arms. Another advantage is the relatively low cost due to the small number of structural components. However, delta 3D printers have received limited use. The main reason is the low positioning accuracy of the end effector. Errors in the manufacture and assembly of components of a parallel drive mechanism add up geometrically and cause an error in the position of the end effector. These formulas can be applied to a 3D printer as well. However, well-known studies consider deterministic models. Therefore, the analysis is performed for limiting size errors. The purpose of this article is to simulate the effect of statistical errors in displacements and arm lengths on the positioning errors of a platform with the end effector. The article effectively complements the field of error analysis research and provides theoretical advice on error compensation for delta 3D printer.

Expansive learning in a change laboratory intervention for teachers

The theory of Expansive learning and the change laboratory (CL) methodology has been developed and applied in many studies on workplace learning and educational change. There are fewer studies made on small-scale interventions, exploring the longitudinal development of expansive learning in an educational change effort. This article examines a CL intervention performed in an upper secondary school in Sweden, with a small group of teachers engaged in a participatory design project. By identifying and analysing the relationship of the seven learning actions posited by the theory of expansive learning, the aim was to contribute to the discussion of the CL methodology and the empirical usability of the theory. The results showed that the seven expansive learning actions functioned as analytical tools to map the teachers learning and development, but the analysis also showed many deviations, disruptions and occurrence of practical actions of design in the process. This challenge the notions of cyclicity and ascension in the theory of expansive learning. Cyclicity might be desirable but not necessary for expansive learning which questions the need to first grasp the problem at a conceptual level before generating concrete solutions. The Findings in this study suggests the opposite; that the entanglement and parallel movement between the abstract and the concrete was a driving force for the teachers expansive learning and the design of new curricular units.

Human Fundamental Movement: Spiral and Parallel by Motion Analysis

Background: Observation and research on pure and natural movements and movements born of human nature have been carried out for many years. However, biomechanics study is still very less for the complex movements from lying on a floor to standing position. In particular, there is still little scientific and scientific research on the movements observed during the unconscious developmental process until babies acquire standing and walking. In this study, two patterns: Spiral and Parallel which relates baby motion development were focused. We examined the characteristics of the changes in the motion trajectory and the body pressure dispersion from the biomechanical point of view in the motion from the floor to standing. Developmental studies of human fundamental movements may be associated with appropriate signals to cells, tissues, and organs, as well as with health maintenance and development and care applications for the sick, disabled, and also the healthy people. This study will provide basic data.Methods: Healthy volunteers who finished training about baby development movement course were recruited by a snowball sampling. Two fundamental Spiral and Parallel movements from a supine position to a standing position on the floor, which are said to reproduce a general developmental process naturally acquired in the growth process of a baby, were analyzed for 5 times each. The three procedure was analyzed with a 42 segments model using a 3D motion analysis VICON. The analysis of observation for the movement process, the force plate, and the movement lotus were examined.Results: One female volunteer aged 30's who finished the training was analyzed in Spiral and Parallel movements for 5 times each. The Spiral movement was distributed to various parts of the body, and repeated circular movements irregularly in a wider space. The Spiral movement was observed a circular trajectory like a figure eight motion as a whole. The Parallel movement was a straight line on the sagittal plane, shifting the body weight back and forth, repeated flexion and extension movements, and moved upward. The motion locus of the linear waveform was repeatedly operated, and it was indicated that it moved back and forth on the sagittal plane in the Parallel movement.Conclusion: The Spiral movement was distributed to various parts of the body, and repeated circular movements in a wider space of sagittal plane, frontal plane and horizontal plane, and moved upward. Spiral movement was a circular trajectory like a figure eight motion irregularly distorted in wider three dimensions. The Parallel movement was a straight line on the sagittal plane, shifting the body weight back and forth, repeated flexion and extension movements, and moved upward. Parallel movement was the operating locus having a linear waveform back and forth on the sagittal plane.

Simulation of the Flat-parallel Movement of a Bridge Agricultural Unit with an Articulated Frame

The work presents foundations of the dynamics of the flat-parallel movement of a bridge agricultural unit in a horizontal with the kinematic method of its control (turning the wheels) by changing the position of one of its parts relative to the other. The analysis of assessment of the degree of impact of the scheme and parameters of the investigated agricultural tool upon its controllability and stability of movement is based on the amplitude and phase frequency characteristics. The mathematical models of the movement of the bridge agricultural unit are presented in a differential and an operator form of recording. Based on mathematical models, the calculated amplitude and phase frequency characteristics of the dynamic control system of the control impact, presented as the angular displacement of its half-frames ψ, are constructed for various parameters and operating modes. The constructed mathematical models, amplitude and phase frequency characteristics make it possible to assess the impact of the control parameter of the bridge agricultural unit, as well as its design and other parameters upon the controllability of the movement.

The determination of the mechanical friction work in a cam –follower couple of complex cam mechanisms. Part I-theoretical aspects

In thispaper we arepresenting theoretical aspects regarding the determination ofthe mechanical friction work presentedin a cam-follower couple, in the case where the follower has a plane parallel movement. An articulated quadrilateral mechanism itis cinematically anddynamically studied, where the connecting rod is actioned by a rotation cam. For showing the relative movement of the contact point on the cam and on the follower, a zero-dimension ring is inserted between the cam and the follower. The expression of the mechanical work is obtained after solving the cinematic and dynamical analysis of the complex rotation cam mechanism. The value of the mechanical work is obtained by integration. The conclusions are presented in the end of the paper and it is mentioned that in a future paper, a numerical application will be made for illustrating the calculation algorithm.