1,721,027 research outputs found
Sensorless position control of solenoid actuators for soft landing using super-twisting sliding mode control
No full text This article presents an open-loop control methodology to achieve lower seating velocities (i.e. soft-landing) for solenoid-based injector systems which are widely used in automotive as fuel injection valves or gas exchange valves of internal combustion engines to spray various fluids. Physical sensors are not preferred to be used in injectors in order to increase reliability and reduce cost. As a result, it becomes impossible to control the motion of the moving parts within injectors in closed-loop. This study offers a novel sensorless position tracking approach with which impact noise can be reduced and mechanical wear and tear can be minimized. Using the Hammerstein-Wiener modeling method and a super-twisting sliding mode controller this new approach replicates the dynamics of the injector and tracks specially designed position reference signals to achieve soft landing. The effectiveness of this approach is based on the observed negligible position and velocity errors between the estimated and actual measurements. This study also offers a new way to optimize the settling time of the injector systems, while ensuring soft landing. Using the proposed approach here, the closing profiles of the reference signals were refined according to the admittance time of the solenoid actuator and the optimal closing profile signals were selected based on performance comparisons with the baseline. The results of the experiments are presented and the promising effectiveness of the proposed approach is discussed. </jats:p
sj-pdf-1-pid-10.1177_09544070221111617 – Supplemental material for Sensorless position control of solenoid actuators for soft landing usingsuper-twisting sliding mode control
No full textSupplemental material, sj-pdf-1-pid-10.1177_09544070221111617 for Sensorless position control of solenoid actuators for soft landing usingsuper-twisting sliding mode control by Muhammad Sarmad Qureshi and Ozkan Bebek in Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering</p
Financial Indicators in Managerial Decision-Making
No full textWorking capital is a financial metric which represent operating liquidity available to a business, organizational or other entity including governmental entities. Along with fix assets such as plant and equipment, working capital is considered a part of operating capital. Collaborator gets the information in working capital because of important changes. Liquidity management is one of the essential features of working capital to keep up ability of a company to pay frequently in short-term. Decision makers needed to indicators and correlations that can keep efficiently determining the real situation and identify the problems of funding in time. It is very complex task to achieving this goal because the use of various indicators and perspectives are essential to measure liquidity. For this, management and structure of organization developed by companies that provide framework to measure the liquidity. To facilitate this, the study draws attention to correlation that anticipates the actual liquidity position of a company more exactly. The database which created and identified of the annual financial statement reporting responsibility that was introduced by the Act in 2000 can be used to analyze company data on a yearly basis. Changes in indicators will be examined frequently during financial year. We need monthly or quartly data and the addition of a suitable accounting information system for the managers to frequently get those created data that are essential for decision making and to receive information about the accomplishment of their department. The aim of study is to show the difference between the emanations of company liquidity results using only year-end data and when liquidity indicators are being accommodated a monthly basis
Sliding mode control of an electromechanical solenoid actuator for soft landing
No full textElectromechanical solenoid actuators are widely used in industrial applications that require fast and linear motion. High velocities can be achieved in small stroke lengths; in turn the motion results with high-velocity impacts, which may cause excessive noise and create mechanical damage to the parts. In this paper, three distinct position reference profiles are tested using Proportional Integral Derivative (PID) control and Sliding Mode Control (SMC) in a closed loop to achieve the soft landing of the actuators plunger. The experimental results reveal that the SMC is robust and can be used to reduce the impact of the fast motion.TÜBİTA
Design of a solenoid based prototype injector for evaluation of electromagnetic parameters
No full textInjector is a pump and valve mechanism, that sprays liquid intermittently to intended volume. In this research, evaluation of the electromagnetic properties of a solenoid actuator used in the prototype injector systems has been studied. ANSYS software has been used to model the three different solenoid actuators based on the specifications of the real solenoid actuators. This paper discusses the simulation approach to evaluate the electromagnetic properties of three different solenoid actuators, along with the validation of the simulated results by the experimental results. A prototype injector to carry out experimental tasks that allows the easy changing of different subsystems for the research and development of injectors concept is designed and manufactured. The simulated and the experimental results show that the applied current and the air gap effects the produced electromagnetic force.TÜBİTA
sj-docx-1-cath-10.1177_10760296211068487 - Supplemental material for Thrombosis with Thrombocytopenia Syndrome After Administration of AZD1222 or Ad26.COV2.S Vaccine for COVID-19: A Systematic Review
No full textSupplemental material, sj-docx-1-cath-10.1177_10760296211068487 for Thrombosis with Thrombocytopenia Syndrome After Administration of AZD1222 or Ad26.COV2.S Vaccine for COVID-19: A Systematic Review by Usama Waqar, Shaheer Ahmed, Syed M.H.Ali Gardezi, Muhammad Sarmad Tahir, Zain ul Abidin, Ali Hussain, Natasha Ali and Syed Faisal Mahmood in Clinical and Applied Thrombosis/Hemostasis</p
sj-xlsx-2-cath-10.1177_10760296211068487 - Supplemental material for Thrombosis with Thrombocytopenia Syndrome After Administration of AZD1222 or Ad26.COV2.S Vaccine for COVID-19: A Systematic Review
No full textSupplemental material, sj-xlsx-2-cath-10.1177_10760296211068487 for Thrombosis with Thrombocytopenia Syndrome After Administration of AZD1222 or Ad26.COV2.S Vaccine for COVID-19: A Systematic Review by Usama Waqar, Shaheer Ahmed, Syed M.H.Ali Gardezi, Muhammad Sarmad Tahir, Zain ul Abidin, Ali Hussain, Natasha Ali and Syed Faisal Mahmood in Clinical and Applied Thrombosis/Hemostasis</p
Mass flow rate control of solenoid-based injectors
No full textThis paper presents a mass flow rate control method for solenoid-based injectors in open-loop, i.e. without physical
sensor feedback. Measuring the mass flow rate in injectors is important because the performance of the injector
determines fuel consumption and emissions. While it is possible to perform this control using different types of sensors,
this would increase the cost and reduce the reliability. With this study, it was aimed to control the mass flow rate
of solenoid-based injectors using continuous switching control to regulate the injector’s needle displacement without
using sensors. For this purpose, a solenoid-actuated injector prototype was created. Model-based estimators were
used to determine the states of the injector, while a super-twisting sliding mode controller was used to track the desired
mass flow rate references. The results of the experiments showed that tracking for sinusoidal, triangular, and square
trajectories yielded a mass flow rate percent error of less than 1.06. The proposed open-loop control algorithm can be
used to track different mass flow rate references in internal combustion engines.Post prin
Designing redundant cable-driven parallel robots for additive manufacturing using end-effector compliance index
No full textThis paper presents a methodology for optimizing cable anchor points for cable-driven parallel robots (CDPRs) for specific additive manufacturing tasks. Much of a CDPR's workspace is generally not used for printing tasks. The unused workspace of the CDPR can be sacrificed to gain greater control to fulfill the printing task. In this paper, the CDPR is designed for a specific task to achieve the best printing results. To find the optimum robot size, the stiffness of the end-effector and mean cable tension are analyzed. The end-effector compliance index (ECI) is proposed to assess the stiffness of the end-effector within the workspace. The ECI uses cable directions to determine the compliance of a given robot pose. From simulation results, a relation to get optimum CDPR frame size is achieved for both suspended and constrained type CDPRs. The proposed method can be used to design low-cost cable-driven robots for additive manufacturing.TÜBİTA
A solenoid injector based drop-on-demand system for generating large droplets
No full textThis paper proposes a drop-on-demand (DOD) system that can produce single droplets of highly repeatable size in the order of 2 mm. This system utilizes an on-the-shelf solenoid injector used in automotive applications. The design methodology is explained along with the necessary measurements and numerical simulations of droplet generation. The invention consists of a solenoid injector that produces monodisperse single or in-series droplets with the help of a developed pulse width modulated signal generator. Mass per injection is measured over a range of supply pressures and injection durations to find the operation window to generate 2 mm droplets. Later, various nozzle geometries are designed and tested by flow simulations. The contracting nozzle is found suitable for generating single droplets, so the design is implemented at the tip of the solenoid injector. The effects of different opening times, pressures, and nozzle’s orifice diameters were tested to observe the operating window of the newly designed DOD system and the repeatability of generated droplets by utilizing a coherent circular Hough transform image processing algorithm to measure droplet sizes. The standard deviation of measured diameters is less than 5% of the mean droplet diameter, which is in the range of 1.68-2.07 mm. Next, the voltage and current signals are measured per injection, and exact instants for the initiation and ending for both opening and closing are determined to construct transient mass flow rate functions for flow simulations in which the dependence of droplet formation on the speed of closing is revealed. The numerical and experimental results indicate the repeatability and consistency of the invention.TÜBİTA
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