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Issue Info: 
  • Year: 

    2018
  • Volume: 

    18
  • Issue: 

    8
  • Pages: 

    71-80
Measures: 
  • Citations: 

    0
  • Views: 

    1117
  • Downloads: 

    0
Abstract: 

One of the most important constraints on manufacturing productivity is the machining vibrations. This vibrations may cause increase in machining costs, lower accuracy of products and decrease tool life. The effective solution for increasing cutting process stability and vibration suppression is to improve structural dynamic stiffness. There has been presented different techniques for enhancing dynamic stiffness of structures using passive and active vibration control methods. Although passive vibration control methods are always stable, they exhibit limited performance. In active control methods, vibrations can be effectively damped over a various conditions. The aim of this research is to enhance the dynamic stiffness of an industrial boring bar by using active damping. Cutting process mainly exposed to parameter perturbations and unknown external disturbances, therefore, designing an active vibration control system for cutting process is a challenging problem. In this research an extended state observer based control strategy was proposed that can overcome these uncertainties. The proposed strategy was implemented into an active vibration control system for a boring bar. Moreover, the direct velocity feedback is successfully implemented in the vibration control loop. The results of impact tests indicate that the control algorithms have a great performance in suppressing vibrations and increasing the structural dynamic stiffness. Voltage impact results show that ADRC controller spends less control effort than direct velocity feedback controller.

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Author(s): 

قدیانی لیلا

Issue Info: 
  • Year: 

    1382
  • Volume: 

    3
  • Issue: 

    (ویژه نامه 10)
  • Pages: 

    56-56
Measures: 
  • Citations: 

    0
  • Views: 

    1665
  • Downloads: 

    0
Abstract: 

مقدمه و هدف: در این مقاله دو روش آموزشی تحت عناوین Case Study ,Case Method به عنوان تکنیکهای آموزشی مورد بررسی و نقد قرار گرفته و تفاوتها و شباهتهای هر کدام به طور جداگانه بررسی شده است و نکات کاربردی هر روش در آموزش پرستاری مورد بحث قرار گرفته است.مرور مطالعات: در این مقاله ابتدا تعاریف دو نوع متد آموزشی ارایه گردیده و سپس موارد استفاده از هر متد به طور جداگانه بحث شده است، و با توجه به ماهیت آموزش پرستاری ایران پیشنهادات کاربردی در این زمینه ارایه شده است. Case Method در گروههای آموزشی کوچکتر که مشاهدات ذهنی کمتری دارند و در ابتدای تجربه می باشند استفاده می شود. ولی Case Study در گروههای آموزشی بزرگتر که مشاهدات ذهنی بیشتری دارند و قدرت تجزیه و ترکیب و رشد بحث در آنها بیشتر می باشد استفاده می شود. از ویژگیهای مهم آنها می توان به افزایش قدرت تصمیم گیری افراد در موقعیتهای مختلف، لذتبخش تر کردن آموزش و علاقمند کردن به امر تدریس و ... نام برد.بحث و نتیجه گیری: با توجه به یافته های پژوهش و با توجه به محتوی برنامه های آموزشی پرستاری، محقق استفاده از روشهای Case Study ,Case Method را برای دانشجویان پرستاری توصیه می نماید. زیرا بهترین آموزش یادگیرنده ها زمانی مطرح می باشد که دانش هماهنگ و متنوع مهارتهای آموزشی با تجربیات در کنار هم می باشد.

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Issue Info: 
  • Year: 

    2015
  • Volume: 

    4
  • Issue: 

    3
  • Pages: 

    117-123
Measures: 
  • Citations: 

    0
  • Views: 

    637
  • Downloads: 

    268
Abstract: 

Control of three phase inverters has been an important issue in recent years. This paper proposes active disturbance rejection control (ADRC) scheme for controlling three phase inverters. The main advantage of ADRC that motivated us for using this controller for inverter is that it is model independent. This controller is used in a double loop structure including an inner current loop and outer voltage loop. A case study has been simulated in SIMULINK to demonstrate the advantages of ADRC in control of inverters over PI controller. Simulation results demonstrate that load changes have no impact on performance of this control method and it is not sensitive to any uncertainty in parameters of the inverter.

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Issue Info: 
  • Year: 

    2025
  • Volume: 

    22
  • Issue: 

    1
  • Pages: 

    93-110
Measures: 
  • Citations: 

    0
  • Views: 

    4
  • Downloads: 

    0
Abstract: 

In this paper, a practical adaptive cruise control system (ACC) with two controller levels is addressed. The upper-level control scheme consists of distance and speed controllers. This controller generates the desired acceleration profile that must be followed as closely as possible by the lower-level controller. A fuzzy adaptive output feedback controller with very high precision produces this desired acceleration. Furthermore, an adaptive observer estimates the states that can’t be measured. The lower-level controller adjusts the throttle and brake actuators. Also, in the lower level, the active disturbance rejection controller (ADRC) eliminates all of the internal and external disturbances applied to the car. The ADRC parameters are tuned via the particle swarm genetic optimization algorithm. The closed-loop stability and semi-globally uniformly ultimately boundedness of all the signals is proved. Also, the asymptotic convergence of the ADRC controller estimation error to zero is insured. To show the effectiveness of the proposed method, the proposed algorithm is compared with a predictive controller, and the performance superiority of the proposed method is demonstrated.

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Issue Info: 
  • Year: 

    1392
  • Volume: 

    1
Measures: 
  • Views: 

    426
  • Downloads: 

    0
Keywords: 
Abstract: 

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Yearly Impact:   مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Journal: 

GEOSCIENCES

Issue Info: 
  • Year: 

    2010
  • Volume: 

    19
  • Issue: 

    75
  • Pages: 

    165-172
Measures: 
  • Citations: 

    0
  • Views: 

    1528
  • Downloads: 

    0
Abstract: 

In this paper we used orthogonal basis functions and expansion coefficients for inverse modeling of magnetic data. The basis functions chosen are normalized eigenvectors of second derivation of the objective function (Hessian matrix) calculate for an initial model. Limited number of basis vectors obtained in this way defines a new subspace in model parameters space. Anew objective function is defined in term of these new parameters and minimized in subspace of original space. As in geophysical inverse problems we need to inverse matrixes that are functions data and geometry of data and model parameters. The matrix inversion in new subspace of the original space will be better conditions due to less dimensionality in the inversion. Since the most significant eigenvectors corresponding the largest Eigen values in Singular Value Decomposition (SVD) of matrixes. Others eigenvectors have less influence in fitting data or lead inversion procedures to local minima. With apply subspace method inversion will be fast and stable against the noise. The efficiency of the method is tested with synthetic and real magnetic data (acquired from Moghan area, north-west of Iran). The results proved fast convergence and stability of inversion against the noise.

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Author(s): 

mahbobeh fadavi mahbobeh fadavi, fadavi mahbobeh

Issue Info: 
  • Year: 

    2023
  • Volume: 

    2
  • Issue: 

    71
  • Pages: 

    95-109
Measures: 
  • Citations: 

    0
  • Views: 

    84
  • Downloads: 

    0
Abstract: 

The Qur'an contains religious values ​​for the advancement of man to happiness. The claim is that Quranic teachings are the basis of religious values; By choosing it better, the method of proving religious beliefs can be extracted. This research tries to extract the method of proving religious beliefs with a business approach and by using artistic forms with a descriptive and analytical method and with a better selection of Quranic teachings. Based on the verses, the process was defined as the introduction to the institutionalization of religious values ​​in the businessman 1- Gaining self-knowledge (knowing the talents, capacities, existential dimensions and position of man in the universe); 2- Gaining monotheistic insight (knowing the origin and your relationship with the Creator); 3- Reciprocity is (knowing the destination and drawing the path of happiness in the universe). After the realization of these three stages, the beliefs must be proven through rational and scientific reasoning and penetrate, in this case, the acceptance of good qualities in the businessman will be facilitated.

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    52
  • Issue: 

    4
  • Pages: 

    269-280
Measures: 
  • Citations: 

    0
  • Views: 

    162
  • Downloads: 

    12
Abstract: 

One of the obvious reasons for most disorders in network service provisioning is network path congestion. Congestion avoidance in today's networks is too costly and sometimes impossible. With the introduction of SDN, centralizing the equipment's control plane has become possible. This paper presents an enhanced method named ESV-DBRA to avoid congestion in multi-tenant SDN networks. At first, ESV-DBRA monitors the traffic load and delay of all network paths for each tenant individually. Then, by merging the parameters obtained from the monitoring, the Service Level Agreements (SLA), and a novel proposed cost function, it calculates the cost of the network paths per tenant. As a result, traffic for each tenant is routed through the path/paths at the lowest possible cost from the tenant's perspective. Next, the bandwidth quotas will be calculated and assigned to the tenants over their optimal routes. Afterward, whenever congestion is likely to occur in a path, ESV-DBRA automatically changes the route or bandwidth of the tenants' traffic related to this path to avoid congestion. Related algorithms are also proposed.Eventually, simulations show that the proposed method effectively increases bandwidth utilization by 10.76%.

Yearly Impact: مرکز اطلاعات علمی Scientific Information Database (SID) - Trusted Source for Research and Academic Resources

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Issue Info: 
  • Year: 

    2022
  • Volume: 

    7
  • Issue: 

    2
  • Pages: 

    253-277
Measures: 
  • Citations: 

    0
  • Views: 

    332
  • Downloads: 

    45
Abstract: 

Objective: People who have higher social health can more successfully deal with the challenges and ups and downs of playing key social roles and participate more in collective activities and prevent social deviations and anomalies. In this regard, foresight and the development of a forward-looking strategy model by the media can play an important role in promoting the social health of their audience (individuals).Method: This research has been done qualitatively and quantitatively. In the qualitative phase, content analysis and Q methods were used, and in the quantitative phase, factor analysis was used to analyze the Q method data.Results: The content analysis of the media in this study showed that the most media production in the field of social deviations with 576 cases and the lowest media production in the field of violence with 237 cases. The field of social quality with 485 and the field of social issues with 312 cases are in the second and third ranks. A small questionnaire was made and based on it, the desired model was designed using PLS software. Conclusion: This model showed that the function of media is effective in promoting social health of society and can have the greatest impact on improving quality of life, reducing violence, reducing social deviations and social issues.

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Author(s): 

Salehi Mehdi | Ahmadi Alireza

Issue Info: 
  • Year: 

    2024
  • Volume: 

    13
  • Issue: 

    25
  • Pages: 

    145-156
Measures: 
  • Citations: 

    0
  • Views: 

    21
  • Downloads: 

    0
Abstract: 

In this article, an attempt has been made to estimate the amount of sound transmission loss in a flat oval channel by applying the approach of statistical energy analysis. Correct estimation of sound transmission loss in an air conditioning channel is of great importance due to the harmful effects of noise pollution in the environment on human health. Simulation with the statistical energy analysis method is a powerful approach to estimate sound and vibration in problems in which we deal with complex and multi-part systems; is considered. In this method, first, a system is divided into several subsystems, and then by writing a matrix equation that includes the energy exchanges between subsystems and energy loss coefficients; It is investigated from the perspective of vibration and sound estimation.On average, the model presented in this research is able to estimate the sound transmission loss in different dimensions of the air conditioning channels according to the experimental results in the accuracy range of ± 2.5 dB. Considering that it seems that the results obtained from modeling with this method are in good agreement with the experimental data; The results of this research can be used as an efficient approach to estimate noise in oval shaped channels stretched in different lengths.

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