active force
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2022 ◽  
Vol 04 (01) ◽  
pp. 488-502
Author(s):  
Metin ŞERİFOĞLU

This research deals with the issue of the Moriscan refugee crisis after the fall of Andalusia to the Spanish in 1492, and the brutal policies they carried out against the refugees. The research also deals with the policy of the Ottoman Empire towards this ordeal, which represented the largest global humanitarian crisis during the 16th and 17th centuries AD. The Ottoman Empire played a major role in the process of saving these Muslim and Jewish refugees, and their homeland in different parts of the Ottoman geography. The Ottoman Empire also succeeded in adopting an integrative policy for these refugees that took into account their social and sectarian specificities, as well as the societal privacy of the new settlement areas. This policy has contributed to creating dynamism and vitality in these areas, and transforming Andalusian refugees into an active force on all cultural, social and economic levels. On the other hand, the Spanish and European refugee crisis revealed the mentality of the issue of religious freedom and the lack of recognition of other religious sects. At the same time, this crisis reflected the Ottoman mentality towards the issue of non-Muslim minorities and how the state interacted with them, and its ability to manage diversity within the Ottoman society. In this context, we will try in this research to present a different analytical approach to the issue of Andalusian Muslim and Jewish refugees, as well as knowing the strategy of the Ottoman Empire towards it and the backgrounds that motivate it. This topic will be addressed through four axes as follows: -First: Andalusia and its importance in attracting immigrants in the Middle Ages -Second: The historical and political circumstances in which the Andalusian refugee crisis arose -Third: The Andalusian refugee crisis and the position of the Ottoman Empire on it -Fourth: The Ottoman Empire's strategy towards the refugee crisis -Fifth: The policy of the Ottomans towards the refugees from Andalusia.


Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8293
Author(s):  
Andrzej Dymarek ◽  
Tomasz Dzitkowski ◽  
Krzysztof Herbuś ◽  
Piotr Ociepka ◽  
Andrzej Niedworok ◽  
...  

The paper formulates a method of active reduction of structure vibrations in the selected resonance zones of the tested object. The method ensures reduction of vibrations of the selected resonance zones by determining the parameters of the active force that meets the desired dynamic properties. The paper presents a method for determining the parameters of the active force by reducing the vibrations of the structure in its resonance zones to a given vibration amplitude. For this purpose, an analytical form was formulated, which will clearly define the dynamic properties of the tested object and the force reducing the vibrations in the form of a mathematical model. The formulated mathematical model is a modified object input function, which in its form takes into account the properties of the active force reducing the vibrations. In such a case, it is possible to use the methods of mechanical synthesis to decompose the modified characteristic function into the parameters of the system and the parameters of the force being sought. In the formulated method, the desired dynamic properties of the system and the vibration reducing force were defined in such a way that the determined parameters of the active force (velocity-dependent function) had an impact on all forms of natural vibrations of the tested system. Based on the formalized method, the force reducing the vibrations of the four-story frame to the desired displacement amplitude was determined. Two cases of determining the active force reducing the vibrations to the desired vibration amplitude of the system by modifying the dynamic characteristics describing the object together with the active force were considered. For both cases, the system’s responses to the oscillation generated by harmonic force of frequencies equal to the first two forms of natural vibrations of the tested system were determined. In order to verify the determined force reducing the vibrations of the object and to create a visualization of the analyzed phenomenon, the building structure dynamics were analyzed with the use of PLM Siemens NX 12 software. The determined force parameters were implemented into the numerical model, in which the tested system was modelled, and the response time waveforms were generated with regard to the considered story. The generated waveforms were compared with the waveforms obtained in the formalized mathematical model for determining the active force reducing the vibrations. The vibrations of the tested numerical model were induced by the kinematic excitation with the maximum amplitude equal to 100 mm, which corresponds to the vibration amplitude during the earthquake with a force equal to level 5 on the Richter scale.


2021 ◽  
Author(s):  
Simon Lo Vecchio ◽  
Olivier Pertz ◽  
Marcela Szopos ◽  
Laurent Navoret ◽  
Daniel Riveline

Directed flows of cells in vivo are essential in morphogenesis. They shape living matter in phenomena involving cell mechanics and regulations of the acto-myosin cytoskeleton. However the onset of coherent motion during collective cell migration is still poorly understood. Here we show that coherence is set by spontaneous alignments of cell polarity by designing cellular rings of controlled dimensions. A tug-of-war between opposite polarities dictates the onset of coherence, as assessed by tracking live cellular shapes and motions in various experimental conditions. In addition, we identify an internally driven constraint by cellular acto-myosin cables at boundaries as essential to ensure coherence and active force is generated as evaluated by the high RhoA activity. Its contribution is required to trigger coherence as shown by our numerical simulations based on a novel Vicsek-type model including free active boundaries. Altogether, spontaneous coherent motion results from basic interplay between cell orientations and active cables at boundaries.


2021 ◽  
Vol 12 ◽  
Author(s):  
Annika Kruse ◽  
Cintia Rivares ◽  
Guido Weide ◽  
Markus Tilp ◽  
Richard T. Jaspers

Treatment strategies and training regimens, which induce longitudinal muscle growth and increase the muscles’ length range of active force exertion, are important to improve muscle function and to reduce muscle strain injuries in clinical populations and in athletes with limited muscle extensibility. Animal studies have shown several specific loading strategies resulting in longitudinal muscle fiber growth by addition of sarcomeres in series. Currently, such strategies are also applied to humans in order to induce similar adaptations. However, there is no clear scientific evidence that specific strategies result in longitudinal growth of human muscles. Therefore, the question remains what triggers longitudinal muscle growth in humans. The aim of this review was to identify strategies that induce longitudinal human muscle growth. For this purpose, literature was reviewed and summarized with regard to the following topics: (1) Key determinants of typical muscle length and the length range of active force exertion; (2) Information on typical muscle growth and the effects of mechanical loading on growth and adaptation of muscle and tendinous tissues in healthy animals and humans; (3) The current knowledge and research gaps on the regulation of longitudinal muscle growth; and (4) Potential strategies to induce longitudinal muscle growth. The following potential strategies and important aspects that may positively affect longitudinal muscle growth were deduced: (1) Muscle length at which the loading is performed seems to be decisive, i.e., greater elongations after active or passive mechanical loading at long muscle length are expected; (2) Concentric, isometric and eccentric exercises may induce longitudinal muscle growth by stimulating different muscular adaptations (i.e., increases in fiber cross-sectional area and/or fiber length). Mechanical loading intensity also plays an important role. All three training strategies may increase tendon stiffness, but whether and how these changes may influence muscle growth remains to be elucidated. (3) The approach to combine stretching with activation seems promising (e.g., static stretching and electrical stimulation, loaded inter-set stretching) and warrants further research. Finally, our work shows the need for detailed investigation of the mechanisms of growth of pennate muscles, as those may longitudinally grow by both trophy and addition of sarcomeres in series.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohd Badrul Salleh ◽  
Nurulasikin Mohd Suhadis ◽  
Renuganth Varatharajoo

Purpose This paper aims to investigate the attitude control pointing improvement for a small satellite with control moment gyroscopes (CMGs) using the active force control (AFC) method. Design/methodology/approach The AFC method is developed with its governing equations and integrated into the conventional proportional-derivative (PD) controller of a closed-loop satellite attitude control system. Two numerical simulations of an identical attitude control mission namely the PD controller and the PD+AFC controller were carried out using the MATLAB®-SimulinkTM software and their attitude control performances were demonstrated accordingly. Findings Having the PD+AFC controller, the attitude maneuver can be completed within the desired slew rate, which is about 2.14 degree/s and the attitude pointing accuracies for the roll, pitch and yaw angles have improved significantly by more than 85% in comparison with the PD controller alone. Moreover, the implementation of the AFC into the conventional PD controller does not cause significant difference on the physical structure of the four single gimbal CMGs (4-SGCMGs). Practical implications To achieve a precise attitude pointing mission, the AFC method can be applied directly to the existing conventional PD attitude control system of a CMG-based satellite. In this case, the AFC is indeed the backbone for the satellite attitude performance improvement. Originality/value The present study demonstrates that the attitude pointing of a small satellite with CMGs is improved through the implementation of the AFC scheme into the PD controller.


2021 ◽  
Author(s):  
Brian A. Petz

In this thesis, a new concept and design is presented for a tool with the purpose of deburring gas turbine engine parts. This new concept utilizes both axial and radial active force compliance to accomplish the burr removal in a more robust manner. The axial and radial components are integrated in a manner that allows them to be decoupled, reducing the complexity of the system. The tool is designed around a pneumatic spindle that is affixed to pneumatic axial actuators. The axial motion system is then affixed to the radial system which makes use of a 2 axis rotary gimbal, acting as a 2-D pivot. Sensors for the axial and radial components of the tool are independent of each other. Axial sensing is accomplished using a commercial string-potentiometer and radial sensing is accomplished using magnets and magnetic field sensors. Burr formation and methods of removal are discussed. Different deburring tool designs available commercially and through literature are then explored. The design process of selecting axial and radial actuation and sensing and integrating them together while keeping the systems decoupled is outlined. Modeling of the tool is then developed and a simulation of the tool is presented to illustrate the deburring mechanics of the decoupled axial and radial components. Experimentation to determine the stiffness qualities of the tool as well as calibration of the sensors are presented and used within the simulation.


2021 ◽  
Author(s):  
Brian A. Petz

In this thesis, a new concept and design is presented for a tool with the purpose of deburring gas turbine engine parts. This new concept utilizes both axial and radial active force compliance to accomplish the burr removal in a more robust manner. The axial and radial components are integrated in a manner that allows them to be decoupled, reducing the complexity of the system. The tool is designed around a pneumatic spindle that is affixed to pneumatic axial actuators. The axial motion system is then affixed to the radial system which makes use of a 2 axis rotary gimbal, acting as a 2-D pivot. Sensors for the axial and radial components of the tool are independent of each other. Axial sensing is accomplished using a commercial string-potentiometer and radial sensing is accomplished using magnets and magnetic field sensors. Burr formation and methods of removal are discussed. Different deburring tool designs available commercially and through literature are then explored. The design process of selecting axial and radial actuation and sensing and integrating them together while keeping the systems decoupled is outlined. Modeling of the tool is then developed and a simulation of the tool is presented to illustrate the deburring mechanics of the decoupled axial and radial components. Experimentation to determine the stiffness qualities of the tool as well as calibration of the sensors are presented and used within the simulation.


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