Design and Evaluation of an Optimal Fuzzy PID Controller for an Active Vehicle Suspension System

The goal of studying the vehicle suspension systems is to reduce the vehicle vibrations which are due to the irregularities of road levels and the fluctuations in the vehicle velocity. These vibrations are transferred to the body and occupants of vehicles through the suspension system. In general, the main function of an active suspension system is to support the vehicle body by reducing the input vibrations and to provide a safe and smooth ride on a bumpy road surface. In this research, a quarter vehicle model has been employed for designing a suspension system. The road level irregularities have been considered as disturbances to this system. The optimal fuzzy PID (OFPD+I) controller has been used to optimize the performance of the suspension system in reducing the adverse effects resulting from road level irregularities, vehicle braking, and moving around the road curves. To verify the efficacy of the optimal fuzzy PID controller, its performance has been evaluated and compared with the performances of three separate controllers (PID, fuzzy, and fuzzy PID) and a system without any controller. The findings indicate the advantage of the optimal fuzzy PID controller over the other systems. Thus, in the integral of the absolute error criterion for the vehicle body velocity and displacement changes, the OFPD+I controller has a superior performance relative to the other systems

Assessment of Measurement Distortions in GNSS Antenna Array Space-Time Processing

Antenna array processing techniques are studied in GNSS as effective tools to mitigate interference in spatial and spatiotemporal domains. However, without specific considerations, the array processing results in biases and distortions in the cross-ambiguity function (CAF) of the ranging codes. In space-time processing (STP) the CAF misshaping can happen due to the combined effect of space-time processing and the unintentional signal attenuation by filtering. This paper focuses on characterizing these degradations for different controlled signal scenarios and for live data from an antenna array. The antenna array simulation method introduced in this paper enables one to perform accurate analyses in the field of STP. The effects of relative placement of the interference source with respect to the desired signal direction are shown using overall measurement errors and profile of the signal strength. Analyses of contributions from each source of distortion are conducted individually and collectively. Effects of distortions on GNSS pseudorange errors and position errors are compared for blind, semi-distortionless, and distortionless beamforming methods. The results from characterization can be useful for designing low distortion filters that are especially important for high accuracy GNSS applications in challenging environments

Nonlinear vibration analysis of directional drill string considering effect of drilling mud and weight on bit

In this paper a nonlinear dynamic model for drill string in inclined well drilling is developed. Effects of drilling mud flow rate, weight on bit, angular velocity along with viscous damping on stability and vibration of the drill string are studied. Findings indicate the nonlinear effects are significant on the results. The effects of drilling mud flow rate and weight on bit on the natural frequencies and time responses are evaluated. Enhancement of drilling mud flow rate results in decreasing of natural frequencies and vibrational amplitude, while increasing the weight on bit, leads to decrease of the natural frequencies and increase the vibrational amplitude

Selection of Conductive Composite Through Weighed Normalized Fuzzy Method in Order to be used in Electrostatics Filters Absorbing Plates

In this paper, due to some problems deriving from using multiple inputs in fuzzy logic procedure, a simpler high demanding method, which can eliminate some complicated fuzzy membership functions trends is represented. This method is so-called weighed normalized fuzzy method. Despite simple calculations used in the method and user capability to use fuzzy membership functions, ranking utilized in this method is as authentic as other conventional fuzzy logic procedures. Regarding suitable properties of composites which can solve problems happening due to intrinsic characteristic of materials used in electrostatic precipitators, in this investigation wide spectrum of resins and fibres used in manufacturing conductive composites is studied. In addition, some of them are selected through material selection methods with regard to their attributes and high conductivity property, which is suitable for absorbing plates. Selecting best conductive composites among considered conductive composites through this novel method is the final aim of this paper. The results show that vinyl ester, which belongs to Vinyl Ester Resin Woven Carbon and Glass (VRWCG) series, has the most beneficial specification in comparison with other thermoset resins for this intended application. Moreover, vinyl ester resins show better stability in acidic electro filter media

Izučavanje CFD-om utjecaja brzine mlaza na miješanje i nastajanje mulja u velikim spremnicima sirove nafte

In this paper, computational fluid dynamic modelling was developed to study the effect of the floating jet velocity or submerged rotary jet in sludge prevention in a large crude-oil storage tank. The Euler-Euler method was used in a two-dimensional CFD model to describe oil and sludge flow behaviour at the bottom of the storage tank. By modifying some parameters, the k-e model was used to describe the turbulence of the mixing flow. The results show the effect of jet velocity, angle, and time on the mixing process. By increasing the velocity from 5 m s–1, the mixing pattern significantly changes and improves the mixing of the sludge with crude oil. To evaluate the results, chosen was the sludge profile related to the bottom of the sample tank, and modelling results showed an 80 cm reduction in thickness of the sludge, which corresponds well to the profile of the bottom of the tank. In addition, the y+ axis indicated that the amounts at all points were less than 300, which is acceptable in two-phase modelling. This work is licensed under a Creative Commons Attribution 4.0 International License.Računalnom dinamikom fluida modeliran je utjecaj brzine mlaza potopljene rotacijske mlazne miješalice na nastajanje mulja u velikim spremnicima nafte. U dvodimezionalnom CFD modelu primijenjena je Euler-Eulerova metoda za opisivanje toka nafte i mulja na dnu spremnika. Uz promjenu nekih parametara modelom k-e opisana je turbulencija toka miješanja. Rezultati pokazuju da na miješanje utječu brzina mlaza, kut i vrijeme miješanja. Povećanjem brzine od 5 m s–1 način miješanja znatno se mijenja i poboljšano je miješanje mulja sa sirovom naftom. Rezultati su procijenjeni proučavanjem odabranog profila mulja na dnu spremnika uzorka, a modeliranje pokazuje smanjenje debljine sloja mulja za 80 cm, što se slaže s profilom dna spremnika. Os y+ u svim točkama pokazuje iznose manje od 300, što je prihvatljivo u dvofaznom modeliranju. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna

The Effect of Operational Cutting Parameters on Nitinol-60 in Wire Electrodischarge Machining

Shape memory alloys are a kind of active materials, which have significant characteristics in comparison with other alloys. Since these materials are applicable in different fields such as aerospace, automobile industry, medicine, and dentistry, the effects of wire electrodischarge machining on the properties of these alloys have been studied. In this paper, changes in the shape recovery ability and microhardness of the machined surface of Nitonol-60 shape memory alloy have been studied considering recasting and formation of resolidificated layer on the shape memory alloy surface. XRD and EDXA analyses of the surface layer of the sample besides a microscopic study of the shape memory alloy layer by SEM and a study of the changes in mechanical properties of the surface layer were done by performing microhardness and tension tests on the work piece surface. Considering the surface layer, reversible strain has been studied according to the shape recovery percentage of Nitinol-60 shape memory alloy. Results show that the surface layer formed on the surface of the samples has caused changes in both physical and mechanical properties of the cut surface because of the penetration of the separated materials in comparison with deeper layers of the piece

The Role of International Trade in the Relationship between Income and Environmental Quality

The Environmental Kuznets Curve (EKC) suggests that environmental quality improves with income after the economy passes an income threshold. Many studies have examined the EKC but the results are mixed. This study Investigates how international trade has affected the EKC’s position. The study uses the ecological footprint, as an indicator of environmental degradation, in 149 countries divided into four income groups for the period 1980-2014. From the panel model estimations, the results confirm an inverted U-shape relationship between the ecological footprint and income. Furthermore, they indicate that trade has altered the position of the EKC, in the entire sample. However, the results vary across income groups. Specifically, the EKC has been shifted by trade upwards in upper-income boundaries. The lower-income countries have not reached the income threshold suggested by the EKC and trade impact on the position of the EKC has not been significant. In this case, it can be inferred that trade worsens environmental degradation

INVESTIGATING ALUMINIUM SHEET WRINKLING DURING THE DEEP DRAWING PROCESS

The purpose of this study is to consider the effect of different parameters on the wrinkling phenomenon of square cups during the deep drawing process. An experimental system was prepared which consisted of a hydraulic press capable of applying different loads on the sheet metal blank and a blank holder and the process was controlled by a computer. All simulations were performed by using the ABAQUS/EXPLICIT V6.9 software, and the effect of different aluminium alloys, punch and die radius, blank holder force, blank holder gap, and friction coefficient on the wrinkling phenomenon has been investigated. Moreover, the minimal blank holder force was obtained by plotting minor strain with respect to the major strain of produced cups, and obtaining the maximum height of wrinkle in a cup. The wrinkling phenomenon was further investigated on different alloys such as A6111-T4, AA5754-O and Al-1050. The results imply that increasing the blank holder force and friction coefficient on the one hand and reducing the blank holder gap, punch radius, and die radius on the other hand, may lead to a reduction in wrinkling during the deep drawing process. Nevertheless, under the same circumstances of the deep drawing process, the wrinkling of the A6111-T4 alloy is more significant compared to the Al-1050 and AA5754-O alloys, while the Al-1050 alloy needs less blank holder force to avoid wrinkling. Using this simulation program it is possible to easily simulate the wrinkling of sheet metal blanks with the least number of trial and error

Nonlinear vibration analysis of directional drill string considering effect of drilling mud and weight on bit

In this paper a nonlinear dynamic model for drill string in inclined well drilling is developed. Effects of drilling mud flow rate, weight on bit, angular velocity along with viscous damping on stability and vibration of the drill string are studied. Findings indicate the nonlinear effects are significant on the results. The effects of drilling mud flow rate and weight on bit on the natural frequencies and time responses are evaluated. Enhancement of drilling mud flow rate results in decreasing of natural frequencies and vibrational amplitude, while increasing the weight on bit, leads to decrease of the natural frequencies and increase the vibrational amplitude

Modelling and investigating the effect of input parameters on surface roughness in electrical discharge machining of CK45

Obrada električnim pražnjenjem je neuobičajeni postupak strojne obrade u kojemu se sukcesivno iskrenje primjenjuje u obradi materijala koji provode elektricitet. Svaka promjena parametara električnog pražnjenja rezultira promjenom površinske hrapavosti uzoraka. Obrada elektičnim pražnjenjem se uspješno primjenjuje kod materijala visoke tvrdoče ili kada se za skidanje čestica teško mogu primijeniti tradicionalne metode. Nadalje, ova se metoda uvelike primjenjuje u aeroindustriji, proizvodnji automobila, oblikovanju, izradi alata. CK45 je važan čelik u industriji i obrada električnim pražnjenjem može se za njega smatrati odgovarajućom zbog postizanja visoke tvrdoće nakon toplinske obrade postupkom električnog pražnjenja. Optimizacija površinske hrapavosti kao izlazni parametar kao i parametri postupka električnim pražnjenjem uključujući struju, napon i frekvenciju, analizirani su primjenom alata od bakra i kerozena kao dielektrika. U tu svrhu, te kako bi se postigla uspješna statistička analiza eksperimentalnih rezultata, primijenjen je plan pokusa te ne-linearna metoda regresije za procjenu površinske hrapavosti. Zatim su se rezultati analizirali pomoću metode ANOVA te odredili parametri obrade s više učinka na željeni rezultat. Na kraju, dobiven je matematički model za površinsku hrapavost.Electrical discharge machining is an unconventional machining process in which successive sparks are applied to machine the electrically conductive materials. Any changes in electrical discharge machining parameters lead to the pieces with distinct surface roughness. The electrical discharge machining process is well applied for high hardness materials or when it is difficult to use traditional techniques to do material removing. Furthermore, this method is widely applied in industries such as aerospace, automobile, moulding, and tool making. CK45 is one of important steels in industry and electrical discharge machining can be considered as a proper way for its machining because of high hardness of CK45 after thermal operation of the electrical discharge machining process. Optimization of surface roughness as an output parameter as well as electrical discharge machining parameters including current, voltage and frequency for electrical discharge machining of CK45 have been studied using copper tools and kerosene as the dielectric. For such a purpose and to achieve the precise statistical analysis of the experiment results design of experiment was applied while non-linear regression method was chosen to assess the response of surface roughness. Then, the results were analysed by means of ANOVA method and the machining parameters with more effects on the desired outputs were determined. Finally, mathematical model was obtained for surface roughness