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List of Articles
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Open Access Article
1 - Robust Anti-Windup Control Design for PID Controllers–Theory and Experimental Verification
Payam KheirkhahanThis paper addresses an approximation-based anti-windup (AW) control strategy for suppressingthe windup effect caused by actuator saturation nonlinearity in proportional–integral–derivative(PID) controlled systems. The effect of actuator constraint is firstl MoreThis paper addresses an approximation-based anti-windup (AW) control strategy for suppressingthe windup effect caused by actuator saturation nonlinearity in proportional–integral–derivative(PID) controlled systems. The effect of actuator constraint is firstly regarded as a disturbanceimported to the PID controller. The external disturbance can then be modeled by a linear differentialequation with unknown coefficients. Using Stone-Weierstrass theorem, it is verified that thesedifferential equations are universal approximators. An auxiliary control signal is finally designed tomodify the error signal injected to the PID controller. The proposed AW control scheme is simple,system independent and applicable by digital or analog circuits. Analytical studies as well asexperimental results using MATLAB/SIMULINK external mode, demonstrate high performance ofthe proposed approach. It is shown that the proposed AW scheme renders the performance of thecontrolled system more robust toward the effects of windup than conventional PID AW schemes.The stability analysis is provided by Lyapunov's second method. Manuscript profile -
Open Access Article
2 - Numerical/Experimental Analysis of the Deformation of Tubes under Concentrated Load
Javad Jafari Fesharaki Omid Rejali Seyed Ghasem MadaniDistortion and deformation of tubes during machining operations are very important. In this study, a tube used in magnetic drum separator under concentrated load (machining load) is considered. Using finite element simulation, deformities and their dependence on paramet MoreDistortion and deformation of tubes during machining operations are very important. In this study, a tube used in magnetic drum separator under concentrated load (machining load) is considered. Using finite element simulation, deformities and their dependence on parameters such as the thickness of the tube and the place of concentrated force are observed and predicted. To compare and confirm the results, some experimental tests are considered. The results show that there is good agreement between the numerical and experimental data. The results of this study indicate the amount of residual stress in the tube by changing the location of the load, the effect of residual stresses in the tube, indentations at different levels of thickness and location of the load. Results show that the values and location of force affect the stress and residual stress in the thickness of tube. In addition, increasing the thickness of tube decreases the residual stress area in longitudinal and circumferential direction of tube. Also, the maximum residual stress in tube is occurring under the force area and by increasing the thickness of tube, the displacements of area under the force is decreased. Manuscript profile -
Open Access Article
3 - Optimization of Spindle loading and Tool Wear for CNC Turning Machine by Using Intelligent System
Morteza Sadegh AmalnikIntelligent knowledge based system (IKBS) is developed for optimizing dry CNC turning process using Taguchi method, CNC Machine, EN19 steel as the work piece material, andCutting Insert. Tool wear and spindle loading which are the machining parameters, spindle speed, fe MoreIntelligent knowledge based system (IKBS) is developed for optimizing dry CNC turning process using Taguchi method, CNC Machine, EN19 steel as the work piece material, andCutting Insert. Tool wear and spindle loading which are the machining parameters, spindle speed, feed rate, and depth of cut, areoptimized through the intelligent knowledge based system (IKBS). The experimental CNC turning machine is used to evaluate IKBS. IKBS is developed to determine the effect of the machining parameters such as tool wear and spindle loading. The simultaneous optimization is done by IKBS. Fourlevels of each machining parameter are used inexperimental verification on Model PTC 600, CNC lathe machinetool of PRAGA. The experimental verification designed based on Taguchi’s method is used to evaluate the effect of the machining parameters on individual responses of IKBS. The simultaneous optimization is done by intelligent knowledge based system. Theoptimization of complicated multi-performancecharacteristics is simplified through this approach. Tool wear and spindle loading are twocharacteristics on the basis of which the machining parameters, spindle speed, feed rate, loading and depth of cut, areoptimized through IKBS. Manuscript profile -
Open Access Article
4 - Organizational Agility and Knowledge Sharing Process in the Staffs of the Iran's Central Plateau Contractor Company
Seyede Parvane Noorbakhsh Samani Molood Sadeghiyan Sirous Keshavarz Fateme ZiglariThis study aimed to investigate the association between organizational agility and knowledge sharing process in the Iran's Central Plateau Contractor Company (ICPCC). For this purpose, one main hypothesis and three subsidiary hypotheses were formulated to assess the rel MoreThis study aimed to investigate the association between organizational agility and knowledge sharing process in the Iran's Central Plateau Contractor Company (ICPCC). For this purpose, one main hypothesis and three subsidiary hypotheses were formulated to assess the relation between organizational agility parameters, leadership and shared identity, strong strategy, and adaptable organizational design, as dependent variables, and knowledge sharing parameters, cooperation, commitment, and culture, as independent variables. To test the hypotheses and gathering the data, two questionnaires were used: Verli and Lover Questionnaire of Organizational Agility and a researcher-developed questionnaire of knowledge sharing. These questionnaires were administered to 170 staffs of the ICPCC selected according to stratified, random sampling. The main hypothesis and three subsidiary hypotheses were confirmed. This means that organizational agility and sharing knowledge were significantly associated (0.43). Moreover, strong strategy, adaptable organizational design, leadership and shared identity were significantly correlated with knowledge sharing (0.45, 0.54, and 0.36, respectively). Manuscript profile -
Open Access Article
5 - Experimental Study of the Cutting Parameters Effect on Hole Making Processes in Hardened Steel
Navid Molla Ramezani Mojtaba Rezaei Hajideh Ali ShahmirzalooHardened steels are commonly used in wide areas of technologies and industries. In respect of poor machinability of these steels and requirement of expensive cutting tools, study of machining economy is a matter of importance. Thus the present study deals with the econo MoreHardened steels are commonly used in wide areas of technologies and industries. In respect of poor machinability of these steels and requirement of expensive cutting tools, study of machining economy is a matter of importance. Thus the present study deals with the economic considerations of various hole making processes. For this purpose, the hard steel samples were machined by conventional drilling and modern helical milling with and without predrilling. The experiments were performed on AISI D2 steel workpieces with a hardness of 52 HRC. The tool wear, surface roughness, cutting forces and machining time were measured. Results revealed that despite general knowledge, applying predrilling step is not a suitable strategy in hole making on hardened steels. Furthermore, helical milling enhances the efficiency of process by improvement of tool life and surface roughness and reducing the cutting forces. The aforementioned results make helical milling a more economical process than conventional drilling. Manuscript profile -
Open Access Article
6 - Numerical Analysis of Delamination Buckling in Composite Cylindrical Shell under Uniform External Pressure: Cohesive Element Method
Sayed Ali Sajjady Saeed Rahnama Mohammad Lotfi Reza NosouhiNowadays, due to high ratio of strength to weight, composite cylindrical shells are extensively used in a great variety of different industrial applications and under different cases of loads. In this study, the buckling of composite cylindrical shells was examined unde MoreNowadays, due to high ratio of strength to weight, composite cylindrical shells are extensively used in a great variety of different industrial applications and under different cases of loads. In this study, the buckling of composite cylindrical shells was examined under uniform external pressure. The buckling analysis of composite cylindrical shells was first done by using theoretical relationships. Doing this, Donnell and improved Donnell equations were employed. Then finite element analysis of composite cylindrical shells was done considering inter-layers delamination. Since delamination is a predominant reason for damage in composite materials, considering different models, the effect of delamination and the factors affecting it (such as the ratio of cylinder length to its cross-section perimeter, delamination size, delamination depth location, and delamination shape) on critical buckling load will be examined. Finally, in the section related to delamination growth, its growth direction and also the effect of embedded delamination shape and size upon delamination growth were examined. The analysis of variance of finite element results show that the area and the depth of delamination with the effectiveness of % 31.92 and % 28.85 have respectively the most effects on critical buckling load. In this study, the 3D modeling of delamination and its growth by using cohesive elements is carried out in ABAQUS software which is the main novelty of this work. Manuscript profile
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