Magnetic circuit optimization of linear dynamic actuators

<p class="Abstract">Contactless braking methods (with capability of energy recuperation) are more and more widely used and they replace the traditional abrasive and dissipative braking techniques. In case of rotating motion, the method is trivial and often used nowadays. But when the movement is linear and fast alternating, there are only a few possibilities to break the movement. The basic goal of research project is to develop a linear braking method based on the magnetic principle, which enables the efficient and highly controllable braking of alternating movements. Frequency of the alternating movement can be in wide range, aim of the research to develop contactless braking method for vibrating movement for as higher as possible frequency. The research includes examination and further development of possible magnetic implementations and existing methods, so that an efficient construction suitable for the effective linear movement control can be created. The first problem to be solved is design a well-constructed magnetic circuit with high air gap induction, which provides effective and good dynamic parameters for the braking devices. The present paper summarizes the magnetostatics design of “voice-coil linear actuator” type actuators and the effects of structure-related flux scattering and its compensation.</p>

Las subpoblaciones de espermatozoides y su calidad en fracciones producidas por la centrifugación de una sola capa en muestras frescas y normospérmicas de esperma de cordero

Single layer centrifugation (SLC) technique has been developed to select the best sperm population in the ejaculate in order to increase the fertilization rates by artificial insemination or in vitro fertilization. Normospermic ram semen samples containing 800 and 3,000 × 106 sperms/ml (C800 and C3000, respectively) were processed by SLC. Three sperm fractions were separated in each sample following silica-coloidal sperm centrifugation and sperm yield, quality and subpopulations were analyzed in each one. In C800 group, the sperm recovery rate did not vary in any studied fraction, but when samples were highly concentrated (C3000) the top fraction (F1) contained significantly higher spermatozoa than bottom fraction (F3). Also, it was observed that F1 in C3000 had got a significantly higher percentage of spermatozoa (53.2 %) than in C800, while the quantity of spermatozoa recovered in fraction 2 was lower (25.2 % vs 45.4 %). Based on the sperm motility parameters, three sperm subpopulations were identified: SP1, low velocity spermatozoa showing no progressive movement (19.1 %); SP2, rapid and progressive spermatozoa (43.7 %); and SP3, rapid spermatozoa but non-linear movement (37.2 %). While SLC has been implemented for sperm separation in suboptimal and/or low concentrated sperm samples, this trial demonstrates that SLC is not efficient to separate different sperm populations in normospermic ram sperm samples containing high concentrations of spermatozoa.

Accuracy of Different Head Movements of Intraoral Scanner in Full Arch of Both Maxilla and Mandible

This in vitro study aimed to compare the accuracy of maxilla and mandible full-arch scans from an intraoral scanner via one scan path with six different head movements. Standard maxilla and mandible models via holder were set in a dental chair to simulate position and posture. The reference models’ standard tessellation language (STL) files were formatted via desktop scanner, and operative models’ files were obtained via IOS TRIOS 3 Pod as superimposed by Exocad CAD software. The same scan path with six head movements (Linear, Circle, Wave, 8-figure, S-figure, and A-P) were designed to scan 10 times per jaw, and a total of 120 scan files were then compared with reference files. The data were recorded and deviations of both occlusal and B-L sides were compared, with statistical analysis being performed by one-way analysis of variance (ANOVA) and post hoc comparisons with Tukey test. The trueness of optical impression for full-arch via one path with six head movements differed from maxilla and mandible and depended on the different movements (p < 0.05). In the same path, peak deviation was found at the turning points for left central incisor, left first premolar, left second molar, and right second molar in maxilla, and for right first premolar, second molar, and left second molar in the mandible. The 8-figure movement showed the highest deviation (0.128 ± 0.086 mm) in the maxilla and (0.105 ± 0.069 mm) in the mandible. The Linear movement presented the lowest deviation (0.096 ± 0.07 mm) in the maxilla while the Circle movement presented the lowest deviation (0.073 ± 0.041 mm) in the mandible, with the 8-figure movement showing the worst precision among six movements. In the maxilla, the S- and 8-figure movements were not recommended, while the Linear and Circle movements showed high trueness. In the mandible, the 8-figure movement was not recommended, while the other five presented similar lower deviations.

Immobility and crisis: rethinking migrants’ journeys through Libya to Europe

Much work on recent unauthorized migration via Libya to Europe – often framed as a migration ‘crisis’ – is focused on linear movement, isolated snapshots and points of arrival on European shores. Migrants’ experiences along their journeys and prior to arriving in Europe, important for their future mobilities, are neglected. By highlighting multi-sited ethnographic fieldwork in Libya and Malta, this paper calls for an analytical focus on immobilities along the journey, so as to develop a more nuanced account of the lived experiences of mobile life. Immobility retrieves situations and relations erased by linear accounts of migration. When looked at in comparative terms through the journey, immobility reveals the variegated forces that shape mobile life.

The First Attempt of Satellite Tracking on Occurrence and Migration of Bryde’s Whale (Balaenoptera edeni) in the Beibu Gulf

Satellite-tagging is increasingly becoming a powerful biotelemetry approach to obtain remote measurement through tracking free-living cetaceans, which can fill knowledge gaps on cetaceans and facilitate conservation management. Here, we made a first biologging attempt on baleen whales in Chinese waters. An adult Bryde’s whale in the Beibu Gulf was tagged to investigate potential occurrence areas and migration routes of this poorly studied species. The whale was satellite-tracked for ~6 days with 71 filtered Argos satellite locations, resulting in a linear movement distance of 464 km. At each satellite-tracking location, the water depth was measured as 42.1 ± 24.8 m on average. During the satellite-tracking period, the whale’s moving speed was estimated at 5.33 ± 4.01 km/h. These findings expanded the known distribution areas of Bryde’s whales in the Beibu Gulf and provided an important scientific basis for the regional protection of this species. We suggest that fine-scale movements, habitat use, and migratory behavior of Bryde’s whales in the Beibu Gulf need more biotelemetry research, using long-term satellite-tracking tags and involving enough individuals. Furthermore, the genetic relationship and possible connectivity of Bryde’s whales in the Beibu Gulf and adjacent waters should be examined.

DEVELOPMENT OF A MICROPROCESSOR CONTROLLER FOR MEASURING THE LINEAR MOVEMENT OF MOVING BODIES OF VIBRATION EXECUTIVE MECHANISMS

Control and measuring equipment is one of the first places in terms of breadth and efficiency of MP-tools. The microprocessor device (MPP) built into the measuring device expands its possibilities, adds new qualities for vibrating machines. Such a device is called programmable (PrVP); WFP can perform the following functions: - control (issuance of control information to all components of the device, reconfiguration of the structure of the device in case of failures of individual units, the formation of control signals to display information, switching different control algorithms); - control of efficiency, reliability of results, diagnostics and localization of malfunctions; - digital information processing (calibration of the device, calculation of errors, determination of minimum and maximum values of parameters, enumeration of parameters, calculation of instantaneous power and signal energy, linearization, information compression, approximation, scaling, normalization, correction, calculation of tolerances, average values, logs , exponentiation, root extraction, transformation of a form from a fixed comma into a floating form and back); - organization of communication with the human operator (exemption from routine operations, such as adjustment, calculation of deviations, etc.; presentation of information in a convenient and accessible for human view form; software support for a functional keyboard that replaces individual control knobs; ensuring the choice of conflict-free position of switches in devices with difficult control); - connection with the system and other devices (implementation of various interface functions, conversion of data formats, adaptation to various input signals). To perform these functions requires the development of an appropriate structure and software MPU. You can implement the following structures for vibrating machines: - universal micro-computer with standard or special programming system; the units of the measuring instrument are connected as external devices - using the address space allocated for external devices; - micro-computers with limited capabilities (for example, limited address space - part of the address bus is given to the addresses of the units of the measuring instrument, while the capacity of RAM is reduced); - special purpose - on the basis of programmable LSI or sectional MP-sets with special software or firmware. The structure of the first type is expedient at development of difficult multipurpose measuring means. The second has fewer features, but requires less hardware, it is useful when building measuring instruments with a small number of blocks and measuring functions. The structure of the third type is aimed at the optimal solution of the measurement problem, requires software development (command systems, microcommands).

A novel method for dendrochronology of large historical wooden objects using line trajectory X-ray tomography

Dendrochronology is an essential tool to determine the date and provenance of wood from historical art objects. As standard methods to access the tree rings are invasive, X-ray computed tomography (CT) has been proposed for non-invasive dendrochronological investigation. While traditional CT can provide clear images of the inner structure of wooden objects, it requires their full rotation, imposing strong limitations on the size of the object. These limitations have previously encouraged investigations into alternative acquisition trajectories, including trajectories with only linear movement. In this paper, we use such a line-trajectory (LT) X-ray tomography technique to retrieve tree-ring patterns from large wooden objects. We demonstrate that by moving a wooden artifact sideways between the static X-ray source and the detector during acquisition, sharp reconstruction images of the tree rings can be produced. We validate this technique using computer simulations and two wooden test planks, and demonstrate it on a large iconic chest from the Rijksmuseum collection (Amsterdam, The Netherlands). The LT scanning method can be easily implemented in standard X-ray imaging units available at museum research facilities. Therefore, this scanning technique represents a major step towards the standard implementation of non-invasive dendrochronology on large wooden cultural heritage objects.

Reconfigurable diplexer using hybrid couplers and perturbed TE012 cavities

A continuously tunable Ku-band waveguide diplexer is proposed in this paper. This diplexer is based on a hybrid coupler topology and is composed of an input filter centered at 11.9 GHz with a 200 MHz bandwidth, a pair of ladder-type hybrid couplers, and a pair of tunable filters. This diplexer can provide two bandpass channels (channels 1 and 2) that can continuously go from a state where the bandwidths of channels 1 and 2 are maximum (up to 140 MHz) and minimum (down to 40 MHz), respectively, to another configuration where the bandwidth of channel 1 is the largest and the bandwidth of channel 2 is the narrowest. We propose a tunable filter based on TE012 mode circular cavities that are perturbed by low-loss dielectric inserts to obtain such performance. The resonant frequency of these cavities can be continuously tuned between 11.8 and 12 GHz due to the linear movement of the dielectric perturber. The design process for these components is presented and a breadboard device has been manufactured and measured to prove the concept. Different measured configurations of the diplexer are demonstrated, showing that the 200 MHz operating bandpass between 11.8 and 12 GHz can be efficiently separated into two tunable channels. The measured bandwidth of channels 1 and 2 in the manufactured diplexer can be tuned from 135 to 40 MHz (and vice versa) while maintaining an average guard band between the channels of approximately 26 ± 7 MHz. The obtained bandwidth tuning ratios are 3.2 for the highest channel and 3.1 for the lowest channel.

Assessment of the Multi-Location External Workload Profile in the Most Common Movements in Basketball

The present study analyzed the multi-location external workload profile in basketball players using a previously validated test battery and compared the demands among anatomical locations. A basketball team comprising 13 semi-professional male players was evaluated in five tests (abilities/skills/tests): (a) aerobic, linear movement, 30-15 IFT; (b) lactic anaerobic, acceleration and deceleration, 16.25 m RSA (c) alactic anaerobic, curvilinear movement, 6.75 m arc (d) elastic, jump, Abalakov test (e) physical-conditioning, small-sided game, 10’ 3 vs.3 10 × 15 m. PlayerLoadRT was evaluated at six anatomical locations simultaneously (interscapular line, lumbar region, knees and ankles) by six WIMU PROTM inertial devices attached to the player using an ad hoc integral suit. Statistical analysis was composed of an ANOVA of repeated measures and partial eta squared effect sizes. Significant differences among anatomical locations were found in all tests with higher values in the location nearer to ground contact (p < 0.01). However, differences between lower limb locations were only found in curvilinear movements, with a higher workload in the outside leg (p < 0.01). Additionally, high between-subject variability was found in team players, especially at lower limb locations. In conclusion, multi-location evaluation in sports movements will make it possible to establish an individual external workload profile and design specific strategies for training and injury prevention programs.