2024-03-29T16:47:24Z
https://eej.aut.ac.ir/?_action=export&rf=summon&issue=64
AUT Journal of Electrical Engineering
2588-2910
2588-2910
2013
45
1
Interval Analysis of Controllable Workspace for Cable Robots
A.
Zarif Loloei
H. D.
Taghirad
N.
N. Kouchmeshky
Workspace analysis is one of the most important issues in the robotic parallel manipulator design. However, the unidirectional constraint imposed by cables causes this analysis more challenging in the cabledriven redundant parallel manipulators. Controllable workspace is one of the general workspace in the cabledriven redundant parallel manipulators due to the dependency on geometry parameters in the cable drivenredundant parallel manipulators. In this paper, a novel tool is presented based on interval analysis fordetermination of the boundaries and proper assessment of the enclosed region of controllable workspace ofcable-driven redundant parallel manipulators. This algorithm utilizes the fundamental wrench interpretationto analyze the controllable workspace of cable driven redundant parallel manipulators. Fundamental wrenchis the newly definitions that opens new horizons for physical interpretation of controllable workspace ofgeneral cable driven redundant parallel manipulators. Finally, the proposed method is implemented on aspatial cable driven redundant manipulator of interest.
Controllable Workspace
Interval Analysis
Cable Driven Redundant Parallel Manipulator
Fundamental Wrench
Boundary of Workspace
Unidirectional Constraint
2013
10
01
1
8
https://eej.aut.ac.ir/article_423_bc8316a2ccce3822e02e02fb0eb2e2fc.pdf
AUT Journal of Electrical Engineering
2588-2910
2588-2910
2013
45
1
Power Quality Improvement in Traction Power Supply Networks
A.
Ghassemi
E.
zarezadeh
S.
Saeed Fazel
AC railway traction loads are usually huge single phase loads. As a result, a significant amount of Negative Sequence Current (NSC) is injected into utility grid. Moreover, harmonics and consumption ofreactive power are further power quality problems that the supply network is encountering. In this paper, acompensation strategy with the aid of Railway Power Conditioner (RPC) is proposed to overcome the abovementionedproblems. Firstly, different kinds of traction transformers are evaluated and Y/Δ tractiontransformer is chosen. Then, a compensation strategy is initiated that is valid for all kinds of tractiontransformers and a control system is proposed based on that. Finally, the correctness of the analysis andproposed strategy is verified by the simulation results using Matlab/Simulink software.
Power Quality
Negative Sequence Current (NSC)
Electrified Railway
Railway Power Conditioner(RPC)
Traction Transformer
2013
10
01
9
15
https://eej.aut.ac.ir/article_427_b159c7dd7734b34a2b7ea5a7474edb9a.pdf
AUT Journal of Electrical Engineering
2588-2910
2588-2910
2013
45
1
Shielding Effectiveness of a Lossy Metallic Enclosure
M.
Pedram
P.
Dehkhoda
H.
Sadeghi
R.
Moini
In this paper, shielding effectiveness (SE) of a perforated enclosure with imperfectly conducting walls is evaluated. To this end, first, an accurate numerical technique based on method of Moments (MoM) ispresented. In this method, lossy metallic walls of the enclosure are replaced by equivalent electric surfacecurrent sources. Then, the impedance boundary condition on the imperfectly conducting surfaces is appliedand an electric field integral equation is extracted. At the end, the integral equation is solved numerically byGalerkin method. In addition to the mentioned numerical method, an extremely fast analytical techniquebased on transmission line model(TLM) is proposed which is able to predict the SE with high level ofaccuracy over a large frequency bandwidth just in a few seconds. For validation of both methods, othercommercial softwares (FEKO and CST) are employed and several enclosures with different conductivitiesare studied. Lossy MoM method shows accurate results for conductivities down to 10S/m, while efficientTLM method proves its accuracy for conductivities down to 250S/m.
Finite Conductivity
Lossy Metallic Box
Shielding Effectiveness
Shielding Enclosure
Transmission Line Method
2013
10
01
17
26
https://eej.aut.ac.ir/article_425_8dae4820318b9c6884ad36be50d062b3.pdf
AUT Journal of Electrical Engineering
2588-2910
2588-2910
2013
45
1
A Novel Flux-Based Protection Scheme for Power Transformers
F.
Haghjoo
M.
Mostafaei
M.
Mohammadzadeh
Internal Turn-Turn faults (TTF) are the most common failures in power transformers, which could seriously reduce their life expectancy. Although common protection schemes such as current-baseddifferential protection are able to detect some of the internal faults, some other minor ones (such as TTFs andshort circuit near the neutral point) cannot be detected by such schemes. Likewise, these relays may havefalse trip due to energizing inrush currents, transformer over excitation, and occurrence of CT saturation atone side. In this paper, a novel Linkage Flux Based (LFB) scheme is proposed to detect TTF in powertransformers, which uses some Search Coils (SC) located on the transformer legs to sense the related linkageflux. Any difference in induced voltage in the corresponding SCs (located on any leg) suggests passingunsymmetrical linkage fluxes through them (unlike the normal conditions), which stands for the occurrenceof a fault inside the transformer. The proposed technique not only can be used to protect power transformers,but also can be employed to find the fault location during repair activities, as well.
Power Transformer
Internal Fault
Search Coil
Linkage Flux
Finite Element Method (FEM)
2013
10
01
27
33
https://eej.aut.ac.ir/article_428_96cbd0f442460f73c09a31fb2b706677.pdf
AUT Journal of Electrical Engineering
2588-2910
2588-2910
2013
45
1
Analysis and Design of High Gain, and Low Power CMOS Distributed Amplifier Utilizing a Novel Gain-cell Based on Combining Inductively Peaking and Regulated Cascode Concepts
Z.
Baharvand
A.
Hakimi
In this study an ultra-broad band, low-power, and high-gain CMOS Distributed Amplifier (CMOS-DA) utilizing a new gain-cell based on the inductively peaking cascaded structure is presented. It is created bycascading of inductively coupled common-source (CS) stage and Regulated Cascode Configuration (RGC).The proposed three-stage DA is simulated in 0.13 μm CMOS process. It achieves flat and high of 26.5 ±0.4 dB over the frequencies range from DC up to 13 GHz 3-dB bandwidth, and it dissipates only 9.95 mW.The IIP3 is simulated and achieved -10 dBm at 6 GHz. Also, simulated input referred 1-dB compressionpoint at 6 GHz achieves the value of -20 dBm. Both input and output matches are better than -11 dB. Toobtain the low power and high gain requirements, the advantages of the bulk terminal are exploited in theproposed CMOS-DA. It adopts the method of forward body biasing in output MOS transistor to achievehigher transconductance and lower power consumption. Additionally, the Monte Carlo (MC) simulation isperformed to take into account the risks associated with various input parameters which they receive little orno consideration in simulating of designs utilizing ideal components. MC simulation predicts an estimate ofthe good accuracy performance of the proposed design under various conditions.
CMOS distributed amplifier
high-gain
ultra-broad band
low power
Regulated Cascode Configuration
2013
10
01
35
50
https://eej.aut.ac.ir/article_424_525035d4dfa952deae800914540bb3cf.pdf
AUT Journal of Electrical Engineering
2588-2910
2588-2910
2013
45
1
Power Amplifier Linearization Using Six-port Receiver for DVB-S2 Satellite Communications
R.
Ebrahimi Ghiri
A.
Mohammadi
A.
Abdipour
R.
Mirzavand
A digital look-up table adaptive predistortion technique using a six-port receiver for power amplifier linearization is presented. The system is designed in Ka-band for a DVB-S2 satellite link. We use a six-port receiver at the linearizationloop in place of classic heterodyne receivers. The six-port receiver is implemented by the use of passive microwavecircuits and detector diodes. This approach highly reduces cost and complexity of the linearization system. Thefabrication results of a five-port receiver operating in 23–29 GHz is presented in this paper. The simulation resultsconfirm suitability of using this architecture in the power amplifier linearization loop. The third order intermodulationproducts and the fifth order intermodulation products reduce about 43 dB and 25 dB respectively, after linearization ofthe power amplifier. The resulting spectrum of the output signal shows significant reduction of the intra-systeminterference to the adjacent networks which is mainly due to the nonlinearity effects of the power amplifier.
Ka-band
Digital Predistortion
Linearization
Six-port
Five-port
2015
09
23
51
58
https://eej.aut.ac.ir/article_484_7768b18d89f6725fc0929de0d798dd9e.pdf