Magnetorheological (MR) damper is a prominent semi-active control device to vibrate mitigation of structures. Due to the inherent
non-linear nature of MR damper, an intelligent non-linear neuro-fuzzy control strategy is designed to control wave-induced
vibration of an offshore steel jacket platform equipped with MR dampers. In the proposed control system, a dynamic-feedback
neural network is adapted to model non-linear dynamic system, and the fuzzy logic controller is used to determine the control
forces of MR dampers. By use of two feedforward neural networks required voltages and actual MR damper forces are obtained,
in which the first neural network and the second one acts as the inverse dynamics model, and the forward dynamics model of
the MR dampers, respectively. The most important characteristic of the proposed intelligent control strategy is its inherent
robustness and its ability to handle the non-linear behavior of the system. Besides, no mathematical model needed to calculate
forces produced by MR dampers. According to linearized Morison equation, wave-induced forces are determined. The performance
of the proposed neuro-fuzzy control system is compared with that of a traditional semi-active control strategy, i.e., clipped
optimal control system with LQG-target controller, through computer simulations, while the uncontrolled system response is
used as the baseline. It is demonstrated that the design of proposed control system framework is more effective than that
of the clipped optimal control scheme with LQG-target controller to reduce the vibration of offshore structure. Furthermore,
the control strategy is very important for semi-active control. 相似文献
Ranking web pages for presenting the most relevant web pages to user's queries is one of the main issues in any search engine. In this paper, two new ranking algorithms are offered, using Reinforcement Learning (RL) concepts. RL is a powerful technique of modern artificial intelligence that tunes agent's parameters, interactively. In the first step, with formulation of ranking as an RL problem, a new connectivity-based ranking algorithm, called RL_Rank, is proposed. In RL_Rank, agent is considered as a surfer who travels between web pages by clicking randomly on a link in the current page. Each web page is considered as a state and value function of state is used to determine the score of that state (page). Reward is corresponded to number of out links from the current page. Rank scores in RL_Rank are computed in a recursive way. Convergence of these scores is proved. In the next step, we introduce a new hybrid approach using combination of BM25 as a content-based algorithm and RL_Rank. Both proposed algorithms are evaluated by well known benchmark datasets and analyzed according to concerning criteria. Experimental results show using RL concepts leads significant improvements in raking algorithms. 相似文献
A semi-active controller-based neural network for a suspension system with magnetorheological (MR) dampers is presented and evaluated. An inverse neural network model (NIMR) is constructed to replicate the inverse dynamics of the MR damper. The typical control strategies are linear quadratic regulator (LQR) and linear quadratic gaussian (LQG) controllers with a clipped optimal control algorithm, while inherent time-delay and non-linear properties of MR damper lie in these strategies. LQR part of LQG controller is also designed to produce the optimal control force. The LQG controller and the NIMR models are linked to control the system. The effectiveness of the NIMR is illustrated and verified using simulated responses of a full-car model. The results demonstrate that by using the NIMR model, the MR damper force can be commanded to follow closely the desirable optimal control force. The results also show that the control system is effective and achieves better performance and less control effort than the optimal in improving the service life of the suspension system and the ride comfort of a car. 相似文献
Protein-surface interactions cause the desirable effect of controlled protein adsorption onto biodevices as well as the undesirable effect of protein fouling. The key to controlling protein-surface adsorptions is to identify and quantify the main adsorption mechanisms: adsorptions that occur (1) while depositing a protein solution onto dry surfaces and (2) after the deposition onto wet surfaces. Bulk measurements cannot reveal the dynamic protein adsorption pathways and thus cannot differentiate between the two adsorption mechanisms. We imaged the interactions of single streptavidin molecules with hydrophobic fused-silica surfaces in real-time. We observed both adsorbed proteins on surfaces and diffusing proteins near surfaces and analyzed their adsorption kinetics. Our analysis shows that the protein solution deposition process is the primary mechanism of streptavidin adsorption onto surfaces at the subnanomolar to nanomolar protein concentrations. Furthermore, we found that hydrophilic fused-silica surfaces can prevent the adsorption of streptavidin molecules. 相似文献
Exponential growth in the usage of “cytokines” (as seroimmunobiomarkers) has facilitated more accurate prognosis, early diagnosis, novel, and efficient immunotherapeutics. Numerous studies have reported immunopathophysiological and immunopathological processes of interleukin-38 (IL-38). Therefore, in this systematic review article, the authors aimed to present an updated comprehensive overview on the immunobiological mechanisms, diagnostic, and immune gene-based therapeutic potentials of IL-38. According to our inclusion and exclusion criteria, a total of 216 articles were collected from several search engines and databases from the January 2012 to July 2021 time interval by using six main keywords. Physiologic or pathologic microenvironments, optimal dosage, and involved receptors affect the functionalities of IL-38. Alterations in serum levels of IL-38 play a major role in the immunopathogenesis of a wide array of immune-mediated disorders. IL-38 shows anti-inflammatory activities by reduction or inhibition of pro-inflammatory cytokines, supporting the therapeutic aspects of IL-38 in inflammatory autoimmune diseases. According to the importance of pre-clinical studies, it seems that manipulation of the immune system by immunomodulatory properties of IL-38 can increase the accuracy of diagnosis, and decipher optimal clinical outcomes. To promote our knowledge, more collaboration is highly recommended among laboratory scientists, internal/infectious diseases specialists, oncologists, immunologists, diseases-specific biomarkers scientists, and basic medical researchers. 相似文献
Micro electro-mechanical systems (MEMS) are increasingly being used in measurement and control problems due to their small
size, low cost, and low power consumption. The vibrating gyroscope is a MEMS device that will have a significant impact on
stability control systems in the transportation industry. This paper investigates the application of a modified model reference
adaptive control for MEMS gyroscope. Using this adaptive control algorithm, an estimation of the angular velocity and the
damping and stiffness coefficients in real time is easily computable. Changing the conventional model reference input makes
it feasible to utilize a low pass filter to remove unwanted oscillations caused by high adaptation gain. This new adaptive
control technique enables quick compensation for large changes in the system dynamics, providing consistent estimation of
gyroscope parameters including angular velocity and large robustness to parameter variations and external disturbances. The
asymptotic stability of the mentioned adaptive controller is guaranteed using the Lyapunov direct method. Numerical simulation
is presented to verify the effectiveness of the proposed control scheme. 相似文献
The reliability of an intelligent self tuning controller called the brain emotional learning based intelligent controller
(BELBIC) to attitude control of a nonlinear launch vehicle (LV) simulation with hardware-in-the loop simulation (HILS) is
studied. To set up the HIL system of the LV a six-degree of freedom simulation of the LV and a hydraulic actuator, which was
used for the pitch channel thrust vector control (TVC) actuator of the LV, is performed. The results of the BELBIC controller
with a fuzzy controller (FC) and a PID controller in this HILS of the LV to control the pitch channel of the LV have been
compared. 相似文献
This research represents an experimental investigation of the metastable flow and re-condensation phenomenon through non-adiabatic lateral helical capillary tubes and suction tube heat exchanger. The results show that mass flux ratio has a vital role: It affects metastable flow and also reverse heat transfer phenomenon through non-adiabatic helical capillary tube. Therefore, by increasing of the mass flux ratio, the rate of heat transfer between them decreases. In contrast to the strong rate condition of heat transfer between them, reverse heat transfer or re-condensation maybe happen. Moreover, experimental results show that for R134 flow with mass flux ratio more than 57.84, metastable flow exists in non-adiabatic capillary tube with 0.9144 mm inner diameter, 30 mm coil diameter, 6.18 m length, 4 mm inner diameter of compressor suction tube.
Journal of Mechanical Science and Technology - This research presents a drift flux model to simulate steady state refrigerant flow through horizontal lateral straight capillary tube-suction line... 相似文献