Zeitschriftenartikel: „Lever-spring“

1

Fawazi, Noor, Jung-Youn Lee und Jae-Eung Oh. „A load–displacement prediction for a bended slotted disc using the energy method“. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 226, Nr. 8 (29.11.2011): 2126–37. http://dx.doi.org/10.1177/0954406211430046.

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A slotted disc spring consists of two segments: a coned disc segment and a number of lever arm segments. In this study, a load–displacement formula for the slotted disc spring is newly developed in the form of energy method by considering both rigid and bending deflections of the two segments. This formula is developed with the aim to further improve the SAE formula which is limited to a straight slotted disc spring. The coned and the lever arm angles of the straight slotted disc spring are the same. They are different for a bended slotted disc spring. Because of this limitation, it is geometrically impractical to employ the SAE formula for a bended slotted disc spring. To achieve the goal of this study, new calculations based on geometric and material properties inputs are developed for a bended slotted disc spring. A firm background study based on the theory of Almen is presented in developing new load–displacement calculations for a bended slotted disc spring.

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Kulik, A. D., A. F. Britachkov, V. A. Tarasenko, A. Ya Publika, S. S. Brodskii und V. V. Nesvet. „Increasing the reliability of lever-spring type slide valves“. Refractories 26, Nr. 1-2 (Januar 1985): 106–8. http://dx.doi.org/10.1007/bf01398629.

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3

Choi, Won-Hong, und Sang-Mok Shin. „The Separating Cover Using an Explosive Bolt and Spring Lever“. Journal of the Korean Society for Aeronautical & Space Sciences 45, Nr. 11 (30.11.2017): 922–31. http://dx.doi.org/10.5139/jksas.2017.45.11.922.

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4

Karditsas, Stylianos, Georgios Savaidis und Michail Malikoutsakis. „Advanced leaf spring design and analysis with respect to vehicle kinematics and durability“. International Journal of Structural Integrity 6, Nr. 2 (13.04.2015): 243–58. http://dx.doi.org/10.1108/ijsi-11-2013-0044.

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Purpose – The purpose of this paper is to provide sound understanding of the mutual interactions of the major leaf spring design parameters and their effects on both the stress behavior of the designed leaf and the steering behavior of the vehicle. Design/methodology/approach – Finite elements analyses have been performed referring to the design of a high performance monoleaf spring used for the suspension of the front axle of a serial heavy truck. Design parameters like eye type, eye lever, spring rate and arm rate difference have been parametrically examined regarding the stress performance and their influence on the wheel joint kinematics. The effect of each design parameter is exhibited both qualitatively and quantitatively. Findings – Eye lever and eye type affect significantly the wheel joint kinematics and therewith the steering behavior of the vehicle. Spring rate and arm rate difference affect solely the stress performance of the leaf spring. Practical implications – Design engineers may use the outcomes of this research as a guide to achieve optimal leaf spring design ensuring its operational strength in conjunction with accurate steering performance of the vehicle. Originality/value – The international literature contains only few, mostly qualitative data regarding the effect of single design parameters on the leaf spring and the corresponding axle kinematics. The present work contains a comprehensive and systematic study of all major leaf spring design parameters, and reveals their effect on both the stress behavior and the steering behavior of the vehicle qualitatively and quantitatively.

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McHenry, Matthew J. „There is no trade-off between speed and force in a dynamic lever system“. Biology Letters 7, Nr. 3 (08.12.2010): 384–86. http://dx.doi.org/10.1098/rsbl.2010.1029.

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Lever systems within a skeleton transmit force with a capacity determined by the mechanical advantage, A. A is the distance from input force to a joint, divided by the distance from the joint to the output force. A lever with a relatively high A in static equilibrium has a great capacity to generate force but moves a load over a small distance. Therefore, the geometry of a skeletal lever presents a trade-off between force and speed under quasi-static conditions. The present study considers skeletal dynamics that do not assume static equilibrium by modelling kicking by a locust leg, which is powered by stored elastic energy. This model predicts that the output force of this lever is proportional to A , but its maximum speed is independent of A . Therefore, no trade-off between force and velocity exists in a lever system with spring-mass dynamics. This demonstrates that the motion of a skeleton depends on the major forces that govern its dynamics and cannot be inferred from skeletal geometry alone.

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Chen, Dongliang, Jindong Zhang, Xutao Weng, Yunjian Zhang und Zhonghui Shi. „Analysis of Stiffness and Energy Consumption of Nonlinear Elastic Joint Legged Robot“. Applied Bionics and Biomechanics 2020 (14.07.2020): 1–10. http://dx.doi.org/10.1155/2020/8894399.

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In order to reduce the energy consumption of the legged robot in walking, this paper designs a kind of nonlinear elastic joint from the flexible variable-stiffness joint based on the mammal walking on the limb and optimizes the leg structure of the legged robot. The motor is rigidly connected to the articulated lever. When the lever is accelerated or decelerated, the elastic unit is introduced. The system can be considered as a special variable-rate elastic system. This paper will study it from theory and simulation experiments. Based on the dynamic analysis, a functional relationship between the output torque and the torsion spring stiffness and between the energy consumption and the torsion spring stiffness was established. By finding the extremum, the two optimum torsional spring stiffness that can minimize the required output average torque and the energy consumed during one cycle of motion were deduced. The results show that using this design in a reasonable position can effectively reduce the energy consumption of the system and can achieve up to a 50% reduction in energy consumption.

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7

Beiner, L. „Variable-Geometry Motion Control of an Aircraft Door“. Journal of Mechanical Design 121, Nr. 2 (01.06.1999): 195–99. http://dx.doi.org/10.1115/1.2829443.

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The paper deals with the motion control of an aircraft door hinged at its lower edge. The door opens under the influence of weight, restrained by cross-mounted air springs and dampers. The goal is to mechanically control the motion so as to bring the door in a specified time from rest at a specified initial position to rest at a specified final position, while minimizing the peak force in the dampers. It is shown that such a velocity profile requires to engage the dampers at an optimized position and simultaneously start to modulate the spring moment so that it equals the weight moment at the final position. A variable-geometry solution is proposed consisting of a mechanical feedback in which the door rotation drives an elongation of the spring levers via bevel gears and screw leads. The associated double two point boundary value problem is solved by casting it into a constrained optimization form, yielding the required damper engagement position, the amount of spring lever extension and the damper lever length. The approach is illustrated by a design example.

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8

French, M. J., und M. B. Widden. „The spring-and-lever balancing mechanism, George Carwardine and the Anglepoise lamp“. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 214, Nr. 3 (01.03.2000): 501–8. http://dx.doi.org/10.1243/0954406001523137.

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Two short and direct methods of exact analysis of the spring-and-lever balancing mechanism are presented. It is shown that perfect balance can be achieved by the use of a close-coiled spring whose free length is effectively zero and whose stiffness is chosen appropriately. The two-degree-of-freedom balancing mechanism, commonly seen in desk lamps but useful in many other situations, is then analysed. The treatment is extended to allow for the weight of the components of the mechanism itself. The originator of these devices was George Carwardine, whose patents over the period 1931–35 show the evolution of his ideas on this subject. A short biographical note is included as an appendix.

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Proksch, Roger, und Jason Cleveland. „Quantifying Molecular Forces: Sensitivities and Spring Constants Without Touching a Surface“. Microscopy and Microanalysis 7, S2 (August 2001): 862–63. http://dx.doi.org/10.1017/s1431927600030385.

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Recent work has demonstrated the ability to measure forces between and within single molecules using cantilever-based instruments. Force measurements on molecules can provide structural and dynamic information not available with other techniques. Figure 1 shows an example force-distance curve made of lambda digest DNA being stretched by a cantilever, showing the characteristic plateau at 65 pN as the DNA goes through the B-S transition. Implicit in these measurements is a need for carefully quantifying the forces the cantilever is exerting on the single molecule. This requires a low noise system that provides accurate measurements of the cantilever spring constant, cantilever bending, and the relative cantilever-sample separation. We have developed an instrument with several improvements that allows these measurements to be made quantitatively. One component is an improved optical lever that provides an extremely sensitive measurement of the cantilever deflection. A separate sensor measures the position of the moving base of the cantilever and allows thermal drift, piezo scanner hysteresis, and creep effects to be corrected.In force measurements with micro-machined cantilevers the application of Hooke's law (F = −kx) requires two quantities: x, the distance the flexing cantilever moves and the “spring constant” k. The optical lever is the most commonly used method for measuring the deflection of a cantilever.

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10

Tsunashima, Hitoshi, Takehiko Fujioka und Masato Abe. „Dynamics of the Mechanical Levitation Control System for Maglev Transport Vehicle (Effect of Guide Wheel Stiffness and Dead Zone Element)“. Journal of Robotics and Mechatronics 7, Nr. 4 (20.08.1995): 329–35. http://dx.doi.org/10.20965/jrm.1995.p0329.

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This paper describes the effect on ride quality and levitation performance of the guide wheel stiffness and the dead zone element of the permanent magnetic suspension system with the mechanical air gap controller. A vehicle dynamic model with the guide wheel stiffness is constructed and the stability criteria for the levitation is derived. The relation between the dynamic characteristics of the vehicle and control lever ratio is analyzed. Seventeen DOF full model simulation results, where nonlinear characteristics of magnet and primary spring are also considered, indicate that the levitation performance of the vehicle is largely affected by the dead zone in the mechanical air gap controller and that the deterioration of the levitation performance can be suppressed by a large control lever ratio.

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FURUKAWA, Yuuki, Hideya YAMAGUCHI und Hidehisa YOSHIDA. „S102035 Linear Friction Damper Consisted of Cylindrical Block and Inclined Lever Supported with Leaf Spring“. Proceedings of Mechanical Engineering Congress, Japan 2012 (2012): _S102035–1—_S102035–5. http://dx.doi.org/10.1299/jsmemecj.2012._s102035-1.

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12

Suh, Jungwook, Joonwoo Lee und Dong-Eun Lee. „Development and Application of Motor-Equipped Reaction Torque Sensor with Adjustable Measurement Range and Sensitivity“. Applied Sciences 10, Nr. 24 (08.12.2020): 8770. http://dx.doi.org/10.3390/app10248770.

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Various high-performance force/torque sensors have been developed for the purpose of advancing automation systems. However, the demand for simple torque measurement of rotating shafts continues to exist, and expensive multi-axis sensors need not be wasted here. In this paper we propose a simple motor-equipped single-axis reaction torque sensor to measure the applied torque continuously using a load cell. The proposed sensor has long lever and base linkages, and the adjustable moment arm consequently enables adjusting measurement range and sensitivity by repositioning the assembled load cell on the two linkages. This paper shows the design of the proposed torque sensor, and it is evaluated by experiments for various applied torque and lever length. Moreover, the sensor is applied to an existing example: a commercial balanced-arm lamp with and without its balancing spring. The proposed torque sensor can continuously and successfully measure the applied torque, and it will be utilized in various industries and laboratories without much money.

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13

LI, CHUNXIANG, und Q. S. LI. „EVALUATION OF THE LEVER-TYPE MULTIPLE TUNED MASS DAMPERS FOR MITIGATING HARMONICALLY FORCED VIBRATION“. International Journal of Structural Stability and Dynamics 05, Nr. 04 (Dezember 2005): 641–64. http://dx.doi.org/10.1142/s0219455405001763.

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The lever-type multiple tuned mass dampers (LT-MTMD), consisting of several lever-type tuned mass dampers (LT-TMDs) with a uniform distribution of natural frequencies, are proposed for the vibration control of long-span bridges. Using the analytical expressions for the dynamic magnification factors (DMF) of the LT-MTMD structure system, an evaluation, with inclusion of the LT-MTMD stroke, is conducted on the performance of the LT-MTMD with identical stiffness and damping coefficients but unequal masses for mitigating harmonically forced vibrations. The LT-MTMD is found to possess the near-zero optimum average damping ratio regimen when the total number of dampers exceeds a certain value. In comparison, the LT-MTMD without the near-zero optimum average damping ratio and the traditional hanging-type multiple tuned mass dampers (HT-MTMD) without the near-zero optimum average damping ratio can achieve approximately the same optimum frequency spacing (an indicator for robustness), effectiveness, and stroke. Compared with the HT-MTMD, the LT-MTMD needs lesser optimum average damping ratio but significantly higher optimum tuning frequency ratio. Its main advantage is that the static stretching of the spring may be adjusted to meet the practical requirements through the support movement, while maintaining the same robustness, effectiveness, and stroke. Consequently, the LT-MTMD is a better choice for suppressing the vibration of long-span bridges as the static stretching of the spring required is not large.

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14

Hirata, Mitsuo, Tsutomu Ogiwara, Hitoshi Okamoto, Shuichi Adachi, Kensuke Osamura und Shinya Kobayashi. „Power Assist H_∞ Control of Shift Lever with Spring Connected Link“. IEEJ Transactions on Industry Applications 127, Nr. 11 (2007): 1133–40. http://dx.doi.org/10.1541/ieejias.127.1133.

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15

Hegde, Sudarshan, und G. K. Ananthasuresh. „A spring-mass-lever model, stiffness and inertia maps for single-input, single-output compliant mechanisms“. Mechanism and Machine Theory 58 (Dezember 2012): 101–19. http://dx.doi.org/10.1016/j.mechmachtheory.2012.01.006.

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16

YAMAGUCHI, Hideya, Yuuki FURUKAWA und Hidehisa YOSHIDA. „Study of linear friction damper consisting of tilt lever supported with leaf spring and cylindrical block“. Transactions of the JSME (in Japanese) 80, Nr. 814 (2014): DR0158. http://dx.doi.org/10.1299/transjsme.2014dr0158.

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17

Makarov, V. N., S. Ya Davydov, V. M. Tauger und N. V. Makarov. „The efficiency upgrading of the high angle belt bulk conveyor“. NOVYE OGNEUPORY (NEW REFRACTORIES), Nr. 9 (29.12.2018): 10–13. http://dx.doi.org/10.17073/1683-4518-2018-9-10-13.

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The high angle belt conveyor with the cross ridge partitions is proposed in the article which allows to increase significantly not only its belt angle but also the transported weight cargo at the expense of the more eﬀective flling and resistance to the force of gravity. The methodology of the high angle belt conveyor calculation is fnalized with regard to the defning of the forces and strains which inﬂuence the pressing lever. The graphical and mathematical models are proposed to depict the force interaction between the substructure elements and the transported weight load. The equation was derived for the maximum bending moment due to the conveyor structural features which now allows to calculate both the geometrical parameters of the press lever and the necessary compressed spring force. Taking into account the friction coefcient, the force of gravity and the additional force which is transmitted on both the diaphragm and the conveying belt the optimal range of the conveyor's belt angle was defned which provides the material consumption reduction at the designed productivity comparing with the conventional conveyors.Ill.4. Ref. 8.

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Zhang, Xiao Hong, Xue Mei Han, Jun Hu und Yang Liu. „The Design of Climbing Rod Car“. Advanced Materials Research 1037 (Oktober 2014): 45–48. http://dx.doi.org/10.4028/www.scientific.net/amr.1037.45.

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Combining the principle of practical car and some of the pole machine in life, using the flat quadrilateral mechanism and institutions, the ratchet wheel and pawl springs structure, sprocket, chain transmission, I cleverly put forward a kind of car that can attach to the surface of the rod , climb vertically and be controlled remotely. On the structure, the unique spring clamping compensation mechanism realize the variable diameter bar crawling easily. Clever lever principle to institutions of successful implementation of its own gravity can be converted to climb bar pressure, which can overcome the climb machine is limited by its own gravity.

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Bapat, Darshan D. „Design, Analysis and Fabrication of Foot Operated Round Ring Cloth Peg Assembly Machine using Spring Lever Mechanism“. International Journal for Research in Applied Science and Engineering Technology 7, Nr. 12 (31.12.2019): 776–89. http://dx.doi.org/10.22214/ijraset.2019.12123.

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20

Chattaraj, Nilanjan, G. K. Ananthasuresh und Ranjan Ganguli. „Design of a distributed compliant mechanism using spring-lever model and topology optimization for piezoelectrically actuated flapping wings“. Mechanics of Advanced Materials and Structures 28, Nr. 2 (02.01.2019): 118–26. http://dx.doi.org/10.1080/15376494.2018.1549295.

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21

Kim, J., S. Park, C. Seok, H. Song, D. Sung, C. Lim, J. Kim und H. Kim. „Simulation of the shift force for a manual transmission“. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 217, Nr. 7 (01.07.2003): 573–81. http://dx.doi.org/10.1243/095440703322114951.

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A shift force simulator for manual transmission is developed to estimate the shift force that is transmitted to the driver's hand. In order to develop the simulator, dynamic models of the external linkage, internal linkage, synchronizer and drivetrain are obtained. The synchronizing motion is modelled as seven steps depending on the relative displacement of the sleeve to the ring spring, outer ring chamfer and gear chamfer. The chamfer-to-chamfer contact mechanism is modelled as a linear spring. In addition, a driver model is proposed to simulate the driver's shift lever operation. Based on the dynamic model of each element, a shift force simulator is developed. The simulator calculates the sleeve displacement, cone torque, index torque, sleeve force, shift force and the speed of the input and output shaft. It is found that the shift force by the simulator shows a good correlation with the test results, and it is expected that the shift force simulator developed in this study can be used as a useful design tool to evaluate the shift feeling in the initial design stage.

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SUYAMA, Shigeaki, Mariko KAWAMOTO, Hiroshige MATSUOKA und Shigehisa FUKUI. „5709 Data Correction Method for Dynamic Measurements by Optical Lever AFM : Effect of Added Spring at the Cantilever End“. Proceedings of the JSME annual meeting 2006.7 (2006): 359–60. http://dx.doi.org/10.1299/jsmemecjo.2006.7.0_359.

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23

Shao, Xin Jie, Guang Tian, Jin Hua Liu, Li Li Yang und Yun Guang Qi. „Simulation Experiment of Certain Equipment of Mortal-Howitzer“. Applied Mechanics and Materials 543-547 (März 2014): 1623–26. http://dx.doi.org/10.4028/www.scientific.net/amm.543-547.1623.

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Based on the structure analysis of certain mortal-howitzer breech mechanism, virtual prototype is established by using Pro/E software an ADAMS. Dynamics models of breech mechanisms breechblock opening plate, closing lever and closing spring are established by simulating breech mechanisms working process when mortal-howitzer is during a shoot and manual. Simulate breech mechanisms working process when mortal-howitzer is during a shoot and manual. Such as, model of driving force during a shoot, the simulation of breech mechanism movement characters, and Dynamics simulation of breech mechanism in the course of contact. These models are carried out simulation experiment. The result shows simulation result is consistent with actual working condition of breech mechanism and proves validity of designed models.

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Tanaka, Takayuki, und Hiroyuki Sugiyama. „Prediction of railway wheel load unbalance induced by air suspension leveling valves using quasi-steady curve negotiation analysis procedure“. Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 234, Nr. 1 (06.08.2019): 19–37. http://dx.doi.org/10.1177/1464419319867179.

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While air suspensions are widely utilized for passenger railway vehicles as secondary suspension, initial lever angle setting of the air spring levelling valve can make a non-negligible impact on the residual wheel load unbalance in curve negotiation on small radius curved tracks. To enable accurate and quick prediction of the levelling valve-induced residual wheel load unbalance for vehicle safety evaluation, this study proposes a new quasi-steady curve negotiation analysis procedure considering the detailed thermodynamic air suspension system model that accounts for the nonlinear airflow characteristics of levelling valve and differential pressure valves. This approach allows for eliminating a limitation of existing full dynamic simulation models associated with high computational intensity that prevents quick safety evaluation with long-distance simulation under actual railway operating scenarios. A co-simulation scheme for the quasi-steady vehicle motion solver is also proposed to further improve the computational efficiency with explicit force–displacement coupling. Several numerical examples are presented to demonstrate the proposed quasi-steady vehicle motion solver for prediction of levelling valve-induced residual wheel load unbalances in small radius curved tracks. The numerical results are compared with those of the dynamic simulation model and validated against the test data. It is demonstrated that computational time is substantially decreased by the proposed approach while accurately predicting the levelling valve-induced residual wheel load unbalance caused by the initial offset of lever angles on small radius curved tracks.

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Yin, Edward, Emmanuel M. Seckley, Evans Kesse Asiedu und Stephen Cobbinah. „STRESS ANALYSIS AND TOPOLOGY OPTIMIZATION OF A CHAIN BUCKET ELEVATOR USING ANSYS“. Acta Polytechnica 61, Nr. 1 (01.03.2021): 292–306. http://dx.doi.org/10.14311/ap.2021.61.0292.

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A failure of conveyor chain links in a production process can cause unscheduled shutdowns, which increase the throughput time coupled with damaged buckets and chain links, which increase maintenance and repair costs. Since failures of conveyor chains are inevitable, this research aims to modify the design of the chain bucket elevator by incorporating a ratchet mechanism, which will prevent the chain bucket assembly from dropping to the bottom of the chain bucket elevator whenever there is a chain-link failure and also avoid the jamming of the bucket chain assembly against one another when dropping to the bottom of the elevator during failure. The number of damaged buckets and chains will be minimal, thereby reducing the maintenance and repair costs. Also, the time required for replacing the failed chain link will be reduced, which in turn, will reduce the down-time, thereby increasing the production rate. The ratchet mechanism, which can withstand a maximum load of 38.10 kN, comprises a toothed wheel, a pawl, and a spring. An analytical method was employed for the initial analysis and the results were verified using the FEM. Topology Optimization was carried out on the beam and lever with results showing a 20% and 26% weight reduction from the original, respectively. The stresses induced in the beam and lever increased significantly by 36% and 47 %, respectively, because of the optimization, however, they remained within the acceptable limits.

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MAHMALAT, MOUNIR, und DENISE SUMPF. „ENTREPRENEURSHIP AND GOVERNANCE IN THE ARAB REGION — A REVIEW OF RECENT LITERATURE TO PRIORITIZE POLICY CHALLENGES“. Journal of Developmental Entrepreneurship 25, Nr. 01 (März 2020): 2050006. http://dx.doi.org/10.1142/s1084946720500065.

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The “Arab Spring” drew attention worldwide to the dire socio-economic conditions in many Arab countries. Efforts to explain, address and resolve these challenges led to a surge in both academic research as well as a plethora of policy recommendations from very different perspectives. By focusing on a crucial area for employment and growth in the Arab region — economic governance and entrepreneurship — the present paper consolidates the vast research and policy recommendations available based on a ‘best evidence’ approach and identifies three priority policy challenges to facilitate entrepreneurship: competition policy, access to finance and entrepreneurial education. We argue that improvement of economic governance tailored to improve these policy areas is a crucial lever for promoting entrepreneurship and creating employment in Arab countries. Highlighting interdependences between these areas, we derive a set of recommendations for each of the identified policy challenges.

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Kámán, Judit, Róbert Huszánk und Attila Bonyár. „Towards more reliable AFM force-curve evaluation: A method for spring constant selection, adaptive lever sensitivity calibration and fitting boundary identification“. Micron 125 (Oktober 2019): 102717. http://dx.doi.org/10.1016/j.micron.2019.102717.

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SUYAMA, Shigeaki, Yuki HOSHINA, Hiroshige MATSUOKA und Shigehisa FUKUI. „2808 Data Correction Method for Dynamic Measurements by Optical Lever AFM : Effect of Concentrated Mass and Spring at the Cantilever End“. Proceedings of the JSME annual meeting 2005.7 (2005): 159–60. http://dx.doi.org/10.1299/jsmemecjo.2005.7.0_159.

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SIEBERT, TOBIAS, HEIKO WAGNER und REINHARD BLICKHAN. „NOT ALL OSCILLATIONS ARE RUBBISH: FORWARD SIMULATION OF QUICK-RELEASE EXPERIMENTS“. Journal of Mechanics in Medicine and Biology 03, Nr. 01 (März 2003): 107–22. http://dx.doi.org/10.1142/s0219519403000648.

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Quick-release experiments often produce noticeable oscillations on the measured force and length data in the first few milliseconds after the force release. We measured oscillations in experiments with several species (Rattus norvegicus, Galea musteloides, Rana pipiens) and different experimental setups. These oscillations are generally ignored as artifacts. This study investigates the cause of the oscillations. A biomechanical model of the experimental setup was developed consisting of a geometric model describing the setup and a Hill-type muscle-tendon model including the force-length-velocity relation and a linear spring in series. Muscle properties of each muscle were determined by the ISOFIT method. Model calculations and forward simulations of quick-release experiments based on experimentally determined muscle properties reveal that the observed oscillations are not artifacts (instrument and control), but the result of interactions of muscle-tendon properties with the inertia of muscles, bones and lever system.

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Bello, R. Segun, und C. Fabian. „Development and Performance Evaluation of a Spring-Loaded Hand Operated Maize Sheller with Variable Mechanisms“. International Journal of Engineering and Technologies 15 (November 2018): 44–52. http://dx.doi.org/10.18052/www.scipress.com/ijet.15.44.

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A spring-press, variable mechanism hand operated maize sheller was developed, constructed and tested with corn cobs at 12.6% moisture content, wet basis (w.b) and its shelling performances compared. The machine is lever operated with a spring load-return mechanism and a cob constrictor with changeable shelling mechanisms (spike tooth, rasp bar and star tooth), and a tilted tray for grain collection. The overall dimension of the machine is 520mm x 520mm x 400mm. The machine overall performance is 20.62kg/hr shelling capacity, 85.13% shelling efficiency and 2.13% kernel damage. Comparing the performance of the three shelling mechanisms; rasp bar, spike tooth and star tooth, shelling capacity (16.2, 26.0, 19.67) kg/hr.; shelling efficiency (82.22%, 87.19%, 85.97%); and % kernel damage (0.00, 0.74, 0.51) respectively, the star mechanism has a higher capacity of 26.0kg/hr. The mean kernel damage is higher for star tooth, whereas it is zero for rasp bar. In comparison with conventional hand-palm shelling method (100% shelling efficiency, 13.83kg/hr shelling capacity and 0% kernel damage), the hand operated sheller has a better output capacity, reasonable shelling efficiency but slightly higher kernel damage. By implication, machine performance efficiency does not give a true reflection of how effective a system work until the machine capacity is determined. The sheller ease household shelling maize for consumption with initial low production cost of N13, 100.00 (~$30).

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Welte, Lauren, Luke A. Kelly, Glen A. Lichtwark und Michael J. Rainbow. „Influence of the windlass mechanism on arch-spring mechanics during dynamic foot arch deformation“. Journal of The Royal Society Interface 15, Nr. 145 (August 2018): 20180270. http://dx.doi.org/10.1098/rsif.2018.0270.

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The function of the human foot is described dichotomously as a compliant structure during mid-stance and a stiff lever during push-off. The arch-spring and the windlass mechanisms, respectively, describe each of these behaviours; however, their interaction has not been quantified to date. We hypothesized that by engaging the windlass mechanism with metatarsophalangeal joint (MTPJ) dorsiflexion, we would observe stiffening of the arch and reduced energy absorption and dissipation during dynamic compressions of the foot. Using a custom apparatus, the MTPJ angle was fixed at 30 degrees of plantarflexion, neutral or 30 degrees of dorsiflexion for nine participants, with the shank positioned similarly to the end of mid-stance. The arch was compressed at two speeds, with the faster speed comparable to walking around 1.5 m s −1 . Six cameras captured the compression and elongation of the arch, along with other kinematic variables, synchronously with the ground reaction force. Combining these measures, we computed the energy absorbed, returned and dissipated in the arch. Contrary to our hypothesis, when the windlass mechanism was engaged, the arch elongated more, and absorbed and dissipated more energy than when it was not engaged. This engagement of the windlass altered the rotational axis of the mid-foot, which probably oriented the arch-spanning structures closer to their resting length, increasing their compliance. This study provides novel evidence for an interplay between the windlass and arch-spring mechanisms that aids in regulation of energy storage within the foot.

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SUYAMA, Shigeaki, Hiroshige MATSUOKA und Shigehisa FUKUI. „2202 Amplitude Correction Method for Dynamic Measurements by Optical Lever AFM : Effect of Added Mass, Spring and Damping at the Cantilever End“. Proceedings of the Conference on Information, Intelligence and Precision Equipment : IIP 2007 (2007): 197–202. http://dx.doi.org/10.1299/jsmeiip.2007.197.

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Motes, J. E., M. D. McCullough und B. A. Kahn. „538 PB 046 SOIL BEDDING TREATMENTS INFLUENCE PEPPER PLANT ANCHORAGE“. HortScience 29, Nr. 5 (Mai 1994): 508e—508. http://dx.doi.org/10.21273/hortsci.29.5.508e.

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A problem associated with machine harvesting of pepper (Capsicum annuum L.) with a stripper-type harvesting mechanism is plant uprooting. Four soil bedding treatments were compared for effects on uprooting force of Chile and paprika direct field seeded at Bixby, Okla. in 1992 and 1993. Bedding treatments were: 1) no-bed; 2) no-bed with 5 cm of soil hilled to the bases of plants; 3) bedded preplant but bed not maintained throughout the growing season; and 4) bedded preplant and bed maintained throughout the growing season. At harvest plants were cut off 10 cm above the soil surface and uprooting force determined using a wire cable puller, spring scale, and a lever based on a fulcrum. Chile uprooting force was significantly influenced by bedding treatments only in 1993. Paprika uprooting force was influenced in both years. In three of the four studies, bedding treatments 2 and 4 produced plants more strongly anchored than treatments 1 and 3.

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Jeon, Jun Cheol, Quoc Hung Nguyen und Seung Bok Choi. „The Design and Modeling of Jetting Dispenser Actuated by Dual Piezostack Actuator“. Applied Mechanics and Materials 433-435 (Oktober 2013): 72–75. http://dx.doi.org/10.4028/www.scientific.net/amm.433-435.72.

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This article presents performance results of a novel jetting dispenser system actuated dual piezostack actuators. The proposed piezo jetting dispenser system consists of a couple of piezostack actuators, lever mechanism, and needle part. The proposed dispenser can provide a very small dispensing dot size of high viscous adhesive, 10,000cp at 100°C, at a high dispensing flow rate in semi-conductor packaging processes. After describing the mechanism and operating principle of the proposed dispenser, a mathematical model of the system is obtained by considering behaviors of the piezostack, the return spring, the dispensing needle, and the adhesive fluid dynamics. For the computer simulation, the specific geometric dimensions of the proposed jetting dispenser are chosen in order to achieve operation requirements: needle motion amplitude: up to 0.15 mm; operating frequency: up to 500 Hz. With the high viscosity conditions, the dispensed amount of the adhesive and the maximum displacement of the piezo and the needle at 500Hz are evaluated in time domain.

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Philpott, Daniel. „The Religious Roots of Modern International Relations“. World Politics 52, Nr. 2 (Januar 2000): 206–45. http://dx.doi.org/10.1017/s0043887100002604.

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The Protestant Reformation was a crucial spring of modern international relations. Had it lever occurred, a system of sovereign states would not have arrived, at least not in the form or at he time that it did at the Peace of Westphalia. This is the counterfactual the author seeks to sustain. He first advances an elaborated but qualified defense of the conventional wisdom that Westphalia is the origin of modern international relations. He then accounts for how Protestant deas exerted influence through transforming identities and exercising social power. Structural heories, emphasizing changes in material power, are skeptical of this account. The author roots lis empirical defense of ideas in the strong correlation between Reformation crises and polities' interests in Westphalia. A description of the historical causal pathways running from ideas to political interest then follows. Germany and France are brought as cases to illustrate two of these pathways. Finally, the author shows the evidentiary weakness of alternative structural material explanations.

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GUTAREVICH, Viktor, und Marina KONDRATENKO. „DYNAMICS OF TRACTION DEVICE OF MINE SUSPENDED MONOREL ROAD“. Sustainable Development of Mountain Territories 12, Nr. 3 (30.09.2020): 410–17. http://dx.doi.org/10.21177/1998-4502-2020-12-3-410-417.

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During the operation of the mine suspension monorail track and traction device form a mechanical system experiencing high dynamic loads associated with implementation of traction and braking forces. Emerging dynamic loads lead to formation of elastic deformations and oscillations that cause vibrations, which leads to displacement of drive wheels and reduces the implementation of traction. The study of the dynamics of traction device is an important step in improving safety and reliability of monorail transport. The aim of the work is to study dynamics of a friction-type traction device moving along a suspended monorail to assess influence of parameters of the elements of device on the vibrations and nature of interaction of drive wheels with monorail. Research methods. Mathematical modeling of the oscillatory processes resulting from interaction of the running gear of the traction device with the monorail is used. Stages of research include drawing up a design diagram oscillations of drive wheels of the traction device interacting with the monorail, developing a mathematical model for the analysis of vibrations caused by moving loads, also assessing the influence of structural parameters of mechanical system under consideration on nature of oscillations. Research results. The developed mathematical model of friction-type traction device movement allows us to establish relationship between parameters of structural elements of its running gear and pressure mechanism, as well as nature of vibrations that arise. As a result, frequencies of the mechanical system under consideration and maximum deviations were found, which allows you to set optimal device parameters to increase traction and increase lifespan of monorail suspended roads. Findings. It was determined that the frequency range of vibration of drive wheels mainly corresponds to the mid-frequency local vibrations of 16–36 Hz. Increasing length of lever for fixing axles of wheels and reducing their radius leads to formation of low-frequency vibrations with a frequency of less than 15 Hz. When length of lever of drive wheels is more than 0.5 m, shoulder of the spring is more than 0.6 m and radius of drive wheels is less than 0.25 m, vibrations with frequencies below 5 Hz can occur. It was found that increasing the length of lever for securing spring increases the oscillation frequency of one drive wheel and reduces frequency of the other. The difference between these frequencies significantly affects changes in the pressure of the wheels against monorail. When difference between frequencies is more than 10–12 Hz, direction of load changes pulsed, with a maximum swing of 0.02 rad, which reduces formation of fatigue fractures of tire wheels, and moments of decrease and increase in pressing force have a negative effect on traction, leading to slippage of drive wheels. When difference between frequencies is less than 10–12 Hz, direction of the load changes sharply, with a maximum swing of 0.03 rad, which increases deformation and formation of fatigue fractures of tire wheels, and short moments of weakening and increase of pressing force, constituting 0.1–0.3 s does not have a significant negative effect on traction.

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Li, Rui-Jun, Ying-Jun Lei, Zhen-Xin Chang, Lian-Sheng Zhang und Kuang-Chao Fan. „Development of a High-Sensitivity Optical Accelerometer for Low-Frequency Vibration Measurement“. Sensors 18, Nr. 9 (01.09.2018): 2910. http://dx.doi.org/10.3390/s18092910.

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Low-frequency vibration is a harmful factor that affects the accuracy of micro/nano-measuring machines. Low-frequency vibration cannot be completely eliminated by passive control methods, such as the use of air-floating platforms. Therefore, low-frequency vibrations must be measured before being actively suppressed. In this study, the design of a low-cost high-sensitivity optical accelerometer is proposed. This optical accelerometer mainly comprises three components: a seismic mass, a leaf spring, and a sensing component based on a four-quadrant photodetector (QPD). When a vibration is detected, the seismic mass moves up and down due to the effect of inertia, and the leaf spring exhibits a corresponding elastic deformation, which is amplified by using an optical lever and measured by the QPD. Then, the acceleration can be calculated. The resonant frequencies and elastic coefficients of various seismic structures are simulated to attain the optimal detection of low-frequency, low-amplitude vibration. The accelerometer is calibrated using a homemade vibration calibration system, and the calibration experimental results demonstrate that the sensitivity of the optical accelerometer is 1.74 V (m·s−2)−1, the measurement range of the accelerometer is 0.003–7.29 m·s−2, and the operating frequencies range of 0.4–12 Hz. The standard deviation from ten measurements is under 7.9 × 10−4 m·s−2. The efficacy of the optical accelerometer in measuring low-frequency, low-amplitude dynamic responses is verified.

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Sampathkumar, M., A. Sakthivel, P. Tharun Prasad, S. Vinothkumar und R. Vinothkumar. „Design and fabrication of electromagnetic braking system for four wheeler“. South Asian Journal of Engineering and Technology 8, Nr. 1 (08.02.2019): 1–3. http://dx.doi.org/10.26524/sajet190802.

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These brakes designed by controlling for equipment, automobiles and movers are suitable for AC&DC power supplies up to 12 v to 220 v and are suitable for wide range of drum sizes 10 to 380 mm dia these brakes are suitable with a rated torque ranging from 100kg-cm for the smallest brake up to 2000 kg-cm for a 380mm dia at 50% coil rating, the coil remains in circuit for a maximum 5 min out of every 10min. Since these brakes are closed position, the release of brake shoes is affected by energizing the electromagnetic coil which over comes the spring force and shoes are moved clear of drum by lever system so that the drum is free to rotate without any friction. When the power given to the electromagnetic coil the coil gets energized and in turns the plunger pulls down. The plunger in turn operates the arm of the brake and the brake opens. When specied brake drum both pin bush type and flexible geared type can be supplied along with the brakes.

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Prater, C. B., A. L. Weisenhorn, B. Dixon Northern, C. M. Peterson, S. A. C. Gould und P. K. Hansma. „Imaging Molecules and Cells with the Atomic Force Microscope“. Proceedings, annual meeting, Electron Microscopy Society of America 48, Nr. 1 (12.08.1990): 254–55. http://dx.doi.org/10.1017/s0424820100180021.

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The atomic force microscope (AFM) gives topographic images by scanning a sharp stylus over a surface. The stylus is attached to a spring lever which is deflected when the stylus interacts with the surface. The AFM images a surface by measuring deflection as a function of position over the surface. The AFM has given atomic resolution images of both conductors and nonconductors. The AFM has also given images of amino acid polymers with subnanometer resolution. The AFM has imaged samples covered with a liquid and biological processes like blood clotting have been imaged. In this report we present several images that demonstrate the variety of samples that can be imaged with the AFM.The AFM has imaged adsorbed molecules at subnanometer resolution. Figure 1A is an image of the bare (010) surface of the natural zeolite, clinoptilolite. Molecules of t-butanol were then adsorbed onto the surface from the liquid and the sample was imaged again (Fig. IB).Figure 2 is an image of double stranded DNA dried onto mica. The resolution is sufficient to reveal corrugation due to the major groove of the double helix. We are currently working to gain resolution sufficient to sequence single-stranded DNA.

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Chassapis, C., und G. G. Lowen. „The Elastic-Dynamic Modeling of a Press Feed Mechanism“. Journal of Mechanical Design 116, Nr. 1 (01.03.1994): 238–47. http://dx.doi.org/10.1115/1.2919354.

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The development of a mathematical model, describing the elastic-dynamic response of an industrial lever type roll feed mechanism, is presented. This device, which is used in all manner of powerpress work, consists of an RSSR linkage with a bent coupler, an indexing-type sprag clutch, a set of feed and pressure rollers, which move a metal strip into a die, and a disc brake. Its intermittent motion has been characterized by four motion regimes. While the spatial coupler link is considered to have distributed mass and electricity, the clutch model neglects the masses of the sprags and represents the total clutch elasticity by way of a single, nonlinear, massless torsional spring. The derivation of the equations of motion of the coupler and the feed-roller driven metal strip, for the various regimes, is based on Hamilton’s principle. The subsequent application of the method of Kantorovich, wherein the space portions of the coupler motion are expressed in terms of its in and out-of-plane free-vibration modes, makes it possible to obtain coupled ordinary differential equations for the feed-roller motion, as well as the time portions of the coupler deflections.

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Selivonchik, N. M., und N. L. Nesterenko. „Basics of Calculating Anti-Theft Crane Device from Eccentric and Tick-Borne Mechanisms“. Science & Technique 20, Nr. 4 (19.07.2021): 296–301. http://dx.doi.org/10.21122/2227-1031-2021-20-4-296-301.

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According to the requirements of the “Rules for industrial safety of cranes”, anti-theft devices must ensure that cranes under the influence of wind force stop at any point on the track, including at the junction of rails connected by side strips. Various types of anti-theft crane devices recommended for use have a number of disadvantages. Thus, the supply of anti-theft crane devices made in the form of lever grips interacting with the rail head with mechanisms for disengaging and converging grippers with electromechanical, electromagnetic, hydraulic or pneumatic drives complicates their design. There are also known anti-theft crane devices, in which the stopping of cranes on a rail track is carried out by a locking eccentric interacting with the surface of the rail head. The reliability of such devices is insufficient, since, due to the constant force of the spring, the adhesion force of the eccentric to the rail does not depend on the changing wind force. The paper proposes the basics of calculating the anti-theft crane device, representing the kinematic connection of two mechanisms – eccentric and thick-borne, which allows to solve a number of the above problems.

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Tang, Wei, Xincheng Xie, Yukang Ye und Weiwei Qu. „Design of a Fast Temporary Fastener with the Labor-Saving and Reversible Ability“. Coatings 11, Nr. 9 (12.09.2021): 1101. http://dx.doi.org/10.3390/coatings11091101.

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Aircraft panel assembly mainly includes the pre-joining process and the riveting process. In addition, the traditional pre-joining process is mainly executed by bolts, which has problems such as the large tightening torque, inconvenient bilateral tightening, heavy workload, and inconvenient loading and unloading. To solve the above-mentioned problems, a research of new temporary fastener is performed deeply from three levels of quick installation, labor-saving, and reversible ability. This involves (a) employing the lever mechanism and the rapid expansion anchor to implement the rapid clamping and disassembly of working processes by labor-saving; (b) integrating the adjusting spring to overcome the tolerances of parts; and (c) building up the space-cross slide rails to provide the axial clamping forces and the reversible forces. The application of designed fasteners was employed into the production of aircraft panel, and the error between theoretical and experimental values was less than 10%. Besides this, the result showed the good effect in panel clamping and the reliable processes of loading and unloading installation, and will greatly reduce the complexity of pre-joining process, the difficulty of installation, and the comprehensive cost.

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Mason, Lyndon, Eric Swanton, Lauren Fisher, Andrew Fisher und Andrew Molloy. „The Plantar Support of the Navicular-Cunieform Joint“. Foot & Ankle Orthopaedics 3, Nr. 3 (01.07.2018): 2473011418S0033. http://dx.doi.org/10.1177/2473011418s00338.

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Category: Midfoot/Forefoot Introduction/Purpose: Weight-bearing radiographic analysis of pes planus deformities shows, with varying degree of severity, a break in Meary’s line, uncovering of the talar head and an increase in talar-first metatarsal angle. Work by Alsousou (BOFAS 2016) has shown the break in Meary’s line to occur not only at the talonavicular joint (2/3rds of cases) but also at the navicular-cuneiform joint (1/3 rd of cases), distal to the spring ligament and reported posterior tibial tendon insertion. There are currently no anatomical studies analysing the medial longitudinal arch distal to the spring ligament insertion. We aimed to examine this area and assess the anatomy supporting the distal medial longitudinal arch. Methods: We examined 11 cadaveric lower limbs that had been preserved for dissection at the Human Anatomy and Resource Centre at Liverpool University, in a solution of formaldehyde. The lower limbs were carefully dissected to identify the plantar aspect of the medial longitudinal arch Results: In all specimens, the posterior tibial tendon inserted into the plantar medial aspect of the navicular with separate slips to the intermediate and lateral cuneiform. Following insertion, on the navicular, a tendon-like structure extended from this navicular insertion point to the medial cuneiform. This tendon-like structure is statically inserted between the navicular and medial cuneiform allowing the pull of tibialis posterior to act on the navicular and medial cuneiform in tandem. The average width of this ligament (15.2 mm) is much greater than that of the tibialis posterior tendon (9.5 mm). A separate smaller plantar ligament is also present between the navicular and medial cuneiform. Conclusion: The posterior tibialis tendon inserts into the navicular, and what is likely an anthropological remnant, extends onto the medial cuneiform as the navicular cuneiform ligament. This provides a static restraint between two bony insertions and increases the lever arm of the posterior tibial tendon. The major support of the distal aspect of the medial longitudinal arch (i.e. the navicular-cuneiform joint) is provided by the substantial navicular cuneiform ligament.

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Willison, Keith Robert. „The structure and evolution of eukaryotic chaperonin-containing TCP-1 and its mechanism that folds actin into a protein spring“. Biochemical Journal 475, Nr. 19 (05.10.2018): 3009–34. http://dx.doi.org/10.1042/bcj20170378.

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Actin is folded to its native state in eukaryotic cytosol by the sequential allosteric mechanism of the chaperonin-containing TCP-1 (CCT). The CCT machine is a double-ring ATPase built from eight related subunits, CCT1–CCT8. Non-native actin interacts with specific subunits and is annealed slowly through sequential binding and hydrolysis of ATP around and across the ring system. CCT releases a folded but soft ATP-G-actin monomer which is trapped 80 kJ/mol uphill on the folding energy surface by its ATP-Mg2+/Ca2+ clasp. The energy landscape can be re-explored in the actin filament, F-actin, because ATP hydrolysis produces dehydrated and more compact ADP-actin monomers which, upon application of force and strain, are opened and closed like the elements of a spring. Actin-based myosin motor systems underpin a multitude of force generation processes in cells and muscles. We propose that the water surface of F-actin acts as a low-binding energy, directional waveguide which is recognized specifically by the myosin lever-arm domain before the system engages to form the tight-binding actomyosin complex. Such a water-mediated recognition process between actin and myosin would enable symmetry breaking through fast, low energy initial binding events. The origin of chaperonins and the subsequent emergence of the CCT–actin system in LECA (last eukaryotic common ancestor) point to the critical role of CCT in facilitating phagocytosis during early eukaryotic evolution and the transition from the bacterial world. The coupling of CCT-folding fluxes to the cell cycle, cell size control networks and cancer are discussed together with directions for further research.

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Yao, J. E., und G. Y. Shang. „A Simple Scanning Tunneling Microscope with Very Wide Scanning Range“. Proceedings, annual meeting, Electron Microscopy Society of America 48, Nr. 1 (12.08.1990): 314–15. http://dx.doi.org/10.1017/s042482010018032x.

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Scanning Tunneling Microscope (STM) has been a powerful tool for study of surfaces in the range of about 1 micrometer. The small field of view is enough for imaging homogeneous surfaces with atomic or near-atomic resolution. If, however, integrated circuits, gratings and other small “man-made” structures have to be observed, a STM with very wide scan range, for example, 10 to 100 micrometers is needed. In most of the STMs currently in use, three-dimensional scanner are fabricated from piezoceramic stacks, tubes and beams. The maximum scanning range is restricted to about a micrometer because of the maximum allowable control voltage and piezo element dimensions. Recently, Takashima Koshi has constructed a x/y scan stage for observation of grating(1). In a similar point of view, We have designed and built a simple scanner (Fig.1), which includes a base B, a mechanical amplifying device (consisting of a spring lever S and a metal tube M), x/y driving elements D, z control piezo tube P and tip T. The relation between the displacement dx(dy) and applied voltage V for the scanner is described by the equation:dx(dy)=KV(2L+l)/2d. Where, K is the voltage sensitivity in nm/v; L and l are the lengths of M and S respectively; d is the distance between the axis of S and that of D. When L=30mm, l =8mm, d=5mm, k=60nm/v, a scan range of 120μm will be obtained.

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Pan, Xiao-Dong, Paul Zakelj, Cara Adams, Akiko Neil und Greg Chaplin. „Understanding Wet Skid Resistance Testing with the British Pendulum Skid Tester: Analysis of Sliding Noise from Various Filled Compounds“. Rubber Chemistry and Technology 83, Nr. 1 (01.03.2010): 97–122. http://dx.doi.org/10.5254/1.3548268.

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Abstract The British pendulum skid tester (BPST) has been widely adopted for laboratory characterization of wet skid resistance (WSR) for rubber compounds. However, testing results are not yet well explained with material properties. For filled compounds made of the same styrene-butadiene rubber, on a Portland cement concrete surface wetted with water, WSR for compounds filled with inorganic oxides is higher than WSR for compounds filled with carbon black at the same filler volume fraction. However, such difference in WSR is eliminated under ethanol lubrication. Difference in WSR remains under ethanol lubrication between compounds filled with a reinforcing filler and compounds filled with a nonreinforcing filler. Accepting that dynamic deformation of rubber occurs in the frequency range between 103 and 106 Hz during testing with the BPST, loss tangent for the compounds is measured at various low temperatures but fails to correlate with WSR detected under water lubrication. Modification of bulk viscoelasticity from ethanol absorption should not be neglected for consideration of WSR under ethanol lubrication. During testing with the BPST, sliding noise generated by the assemblage of the spring and lever system in the pendulum with a rubber slider attached is captured under varied lubrication conditions. Both viscoelastic properties of rubber compounds and lubrication condition significantly affect sliding noise. However, no strict correlation between the intensity of sliding noise and WSR is observed. From frequency domain analysis, major components of the sliding noise lie in the frequency range between 500 and 5000 Hz for most compounds. For better understanding on testing with the BPST, modes of material deformation during dynamic sliding on a wet rough surface need to be further scrutinized.

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Dang, Minh Phung, Hieu Giang Le, Ngoc N. Trung Le, Ngoc Le Chau und Thanh-Phong Dao. „Multiresponse Optimization for a Novel Compliant Z-Stage by a Hybridization of Response Surface Method and Whale Optimization Algorithm“. Mathematical Problems in Engineering 2021 (22.04.2021): 1–18. http://dx.doi.org/10.1155/2021/9974230.

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A novel compliant z-stage is applied for positioning and indenting a specimen in nano/microindentation testing system. For an excellent operation, the proposed z-stage can concurrently satisfy multicriteria comprising high safety factor, small parasitic motion, and large output displacement. The key aims of this article are to present a novel design of the compliant z-stage as well as an effective integration methodology of Taguchi method, response surface method, weight factor calculation based on signal to noise, and the whale optimization algorithm to resolve a design optimal problem so as to enrich the quality performances of the proposed stage. Primarily, the z-stage is designed based on four-lever amplifier, compliant hinge shifted arrangement mechanism, zigzag-based flexure spring guiding mechanism, and symmetric six leaf hinges-based parallel guiding mechanism. Secondly, the number experiment data are achieved by the Taguchi method and finite element analysis. Subsequently, the regression functions among input variables and quality characteristics are formed by exploiting response surface method. In addition, the weight factors for every characteristic are defined. Additionally, the sensitivity analysis is accomplished for determining influences of input variables on quality responses. Ultimately, based on regression equations, the whale optimization algorithm is executed to define the optimal factors. The consequences indicated that the output deformation is about 454.55 μm and the safety factor is around 2.38. Furthermore, the errors among the optimal consequences and the confirmations for the safety factor and output deformation are 7.12% and 4.25%, correspondingly. By using Wilcoxon and Friedman methods, the results revealed that the proposed algorithm is better than the cuckoo search algorithm. Based on the quality convergence characteristics of hybrid approach, the proposed method is proficient for resolving complicated multiobjective optimization.

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Guo, Jishu, Junmei Guo und Zhongjun Xiao. „Robust tracking control for two classes of variable stiffness actuators based on linear extended state observer with estimation error compensation“. International Journal of Advanced Robotic Systems 17, Nr. 2 (01.03.2020): 172988142091177. http://dx.doi.org/10.1177/1729881420911774.

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In this article, a novel robust tracking control scheme based on linear extended state observer with estimation error compensation is proposed for the tracking control of the antagonistic variable stiffness actuator based on equivalent nonlinear torsion spring and the serial variable stiffness actuator based on lever mechanism. For the dynamic models of these two classes of variable stiffness actuators, considering the parametric uncertainties, the unknown friction torques acting on the driving units, the unknown external disturbances acting on the output links and the input saturation constraints, an integral chain pseudo-linear system with input saturation constraints and matched lumped disturbances is established by coordinate transformation. Subsequently, the matched lumped disturbances in the pseudo-linear system are extended to the new system states, and we obtain an extended integral chain pseudo-linear system. Then, we design the linear extended state observer to estimate the unknown states of the extended pseudo-linear system. Considering the input saturation constraints in the extended pseudo-linear system and the estimation errors of the linear extended state observer with fixed preset observation gains, the adaptive input saturation compensation laws and the novel estimation error compensators are designed. Finally, a robust tracking controller based on linear extended state observer, sliding mode control, adaptive input saturation compensation laws, and estimating error compensators is designed to achieve simultaneous position and stiffness tracking control of these two classes of variable stiffness actuators. Under the action of the designed controller, the semi-global uniformly ultimately bounded stability of the closed-loop system is proved by the stability analysis of the candidate Lyapunov function. The simulation results show the effectiveness, robustness, and adaptability of the designed controller in the tracking control of these two classes of variable stiffness actuators. Furthermore, the simulation comparisons show the effectiveness of the proposed estimation error compensation measures in reducing the tracking errors and improving the disturbance rejection performance of the controller.

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Binfield, Clyde. „The Bolton Prelude to Port Sunlight: W. H. Lever (1851–1925) as Patron and Paternalist“. Studies in Church History 42 (2006): 383–93. http://dx.doi.org/10.1017/s0424208400004095.

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Christ Church United Reformed Church (formerly Congregational), Port Sunlight, and St George’s United Reformed Church (formerly Congregational), Thornton Hough, do not spring to mind as Free Church buildings. There is scarcely one architectural respect in which either announces a Dissenting presence. Each conforms to nationally established tradition. Their quality, however, is as incontestable as it is incontestably derivative. Their role in their respective village-scapes is important, even dominant. As buildings, therefore, they are significant and perhaps suggestive, but do they say anything about ecclesiastical polity? The answer to that question illustrates the interaction between elite and popular religion in Edwardian English Protestant Nonconformity, for the polity to which these two churches give space is in fact successively congregational, Congregational, and Reformed. It is representative throughout but never democratic. Yet can any shade of Congregationalism truly develop in either a squire’s village or a manufacturer’s? And what might be deduced of the man who provided these buildings, created their villages, shaped their communities, and regarded himself lifelong as a Congregationalist even if a masonic lodge were the only fellowship to which he could statedly commit himself? These questions prompt this paper.

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Young, D., und H. Bennet-Clark. „The role of the tymbal in cicada sound production“. Journal of Experimental Biology 198, Nr. 4 (01.04.1995): 1001–20. http://dx.doi.org/10.1242/jeb.198.4.1001.

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1. The tymbal of Cyclochila australasiae consists of a biconvex membrane bearing alternating long and short ribs anteriorly and an irregularly shaped tymbal plate posteriorly. These sclerotised regions are coupled together by the surrounding highly flexible cuticle, which contains resilin. Dorsally, there is a thick pad of resilin, which functions as a spring, returning the tymbal to the out position and maintaining the stress on the long ribs. 2. Contraction of the tymbal muscle causes the tymbal plate to swing inwards, acting as a lever so that the surface of the tymbal moves through more than twice the distance of muscle shortening. This produces an inward movement and twisting of the dorsal ends of the long ribs, which then buckle in sequence, with each rib undergoing a sudden deformation from a convex to a V-shaped profile. Buckling takes place at the rib's weakest point, which is the narrow, highly sclerotised mid-region. 3. Inward buckling of the tymbal generates a loud click with a dominant frequency around 4 kHz. Resonances close to 4 kHz can be demonstrated in a buckled-in tymbal when driven by internal sound or by vibration at the tymbal plate. These resonances occur in sealed cicadas and those in which the abdominal air sac has been opened at both its anterior and posterior ends, which shows that the resonances are not due to the air sac; the tymbal itself is a resonant system. The maximum amplitude of tymbal vibration occurs at the V-shaped dimples in the centre of the long ribs. 4. When the tymbal plus abdominal air sac system is driven by vibration at the tymbal plate, the Q3dB of the sound radiated through the tympana is about 12.5, which is approximately the sum of those of the tymbal (Q=9.3) and of the air sac (Q=3.4) resonators. When the tymbal is not loaded by the air sac, i.e. in the sealed cicada and open cicada preparations, the Q3dB of its resonance is higher, between 13 and 20. 5. The click produced as the tymbal pops out is over 20 dB quieter than the in-click and has a dominant frequency around 6 kHz. When driven in the resting position, resonances are found close to 6 kHz but there is only a weak general vibration of the ribs and tymbal plate. When the tymbal is pushed in gradually, the resonant frequency changes from about 5.5 kHz to about 4.3 kHz as the tymbal buckles inwards. The left and right tymbals of the same insect may differ slightly in their acoustic properties. 6. As the tymbal buckles inwards, it displaces a volume of approximately 6 µl into the abdominal air sac volume of about 2 ml. The resulting sound pressure inside the air sac attains peak values of 155159 dB SPL; the root mean square values are 141144 dB SPL. The mean peak value just outside the tympana is 148.5 dB SPL. 7. Overall, the present work supports and extends our earlier model of cicada sound production: the tymbal click provides a coherent resonant source that drives the abdominal resonator, from which sound is radiated via the tympana. At the same time, the system provides the pressure transformation between muscle power and sound power that is desirable for efficient sound radiation.

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