Eccentricity Fault Detection in Permanent Magnet Synchronous Generators Using Stator Voltage Signature Analysis

Hossein Hooshmandi Safa,Mohammad Ebrahimi,Hossein Abootorabi Zarchi,Mohammad Abshari 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.12

In this paper, an index is proposed for the detection of static eccentricity (SE), dynamic eccentricity (DE), and mixed eccentricity (ME) in a three-phase permanent magnet synchronous generator (PMSG). The proposed index is the amplitude of the sideband components with a particular frequency pattern which is extracted from the spectrum of the stator voltage. This index can be used in no load state prior to the loading of the generator which can cause damage in eccentricity conditions. Moreover, the proposed index works properly in loaded condition. Extraction of the proper indexes highly depends on precise computation of the necessary signals. Therefore, in order to fulfil the required precision, the time-stepping finite element method (TSFEM) is used to model the PMSG under eccentricity fault and to calculate the stator voltage as an appropriate signal for processing.

Response to the Article “Comparison of the Cost-Utility Analysis of Electroacupuncture and Nonsteroidal Antiinflammatory Drugs in the Treatment of Chronic Low Back Pain”

Hossein Ayati 사단법인약침학회 2019 Journal of Acupuncture & Meridian Studies Vol.12 No.1

Dear Editor in Chief,We compared the cost-utility of electroacupuncture and NSAIDs in the treatment of chronic low back pain, and the results were published in JAMS on April 2018. Recently, we received a response to that article, making some questions and raising some great points. With many thanks to the commenting author(s) for the time and consideration, our response is as follows. 1. It is important to explain why NSAIDs were chosen as the comparator and what types and dosing schedules of NSAIDs were studied. According to the international guidelines, NSAIDs are used to treat chronic low back pain, and patients often use these drugs to relieve the pain [1], so these drugs are an appropriate choice to be the standard comparator. Types and dosing of NSAIDs, which was studied, are listed in Table 1 [2]. In this study, the average consumption of these drugs (alone or combined with other NSAIDs) was multiplied with the drug price to obtain the cost of these medications. 2. The costs presented in the study are not transparent. It is challenging to analyze the specific costs, especially the direct nonmedical costs, because they are not specified. In the materials and methods section of the article, a variety of costs and the way they were measured are clearly explained. The direct nonmedical costs include travel, meals, and hoteling costs when patients are receiving medical services. However, in this study, we considered only the travel costs because all participants were residents of Tehran. 3. The study failed to present the results in the appropriate format; cost-utility analyses require results in terms of quality-adjusted life years and incremental cost-utility ratios (ICER). However, only utilities and average costeffectiveness ratios (ACER) were reported in the study. The ACER is the ratio of the cost to benefit of an intervention without any comparisons to alternatives, and ICER is always used when comparing different treatment options Owing to the 1-year study period, cost-utility analysis does not require quality-adjusted life year calculation [3]. According to our results, the cost of the electroacupuncture method was less than NSAID therapy method and the electroacupuncture method was more effective, so the electroacupuncture method is the dominant option, and the NSAID therapy method is a dominated option, and in this situation, it is not necessary to calculate the ICER [4]. The ACER is also reported as an additional calculation in this study. 4. The study did not conduct any sensitivity analysis, thus not allowing for any uncertainty in the estimates of costs and consequences, which were already vague and difficult to decipher. Regarding the sensitivity analysis, when applying the one-way sensitivity analysis, (the variation range was 20% for costs and effectiveness), the results did not change, so the sensitivity analysis results were not presented in the article. However, the results of the one-sided sensitivity analysis are reported here (Fig. 1). We appreciate the commenting authors and hope that the aforementioned explanations are satisfying. Best regards. On behalf of co-authors. M. Hossein Ayati, MD, PhD.

PREVENTION OF SINTERING DURING ANNEALING PROCESS OF FePt NANOPARTICLES COATED WITH ZnO SHELL

HOSSEIN ZEYNALI,HOSSEIN AKBARI,S. ARUMUGAM,ZOHREH CHAMANZADEH,G. KALAISELVAN,REYHANEH KARIMI GHASABEH 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.6

Monodispersed 4.1 nm FePt nanoparticles with narrow size distribution were successfully synthesized by the chemical polyol process with co-reduction of Fe(acac)3 and Pt(acac)2 in the presence of 1,2-hexadecanediol as a reducing agent. To achieve hard ferromagnetic behavior with L10 phase and face center tetragonal (fct) structure, high temperature annealing is performed. Annealing causes the surfactant surrounding particles to decompose and agglomeration of particles occurs. In the present work, chemically synthesized FePt nanoparticles were coated with nonmagnetic ZnO oxide shell to prevent them from sintering. Coercivity of FePt and FePt/ZnO nanoparticles increases from 5 kOe to 10 kOe and 1.8 kOe to 6 kOe respectively, with the increasing annealing temperatures from 650 to 750?C.

A New Iron Chelate and Its Effects on Photosynthesis Activity, Chlorophyll Content and Nutrients Uptake of Pistachio (Pistacia vera L.)

Hossein Hokmabadi,Ali Haidarinezhad,Reza Barfeie,Mohammad Hassan Nazaran,Mohammad Ashtiani,Abdol Hossein Aboutalebi 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

Date seed activated carbon decorated with CaO and Fe3O4 nanoparticles as a reusable sorbent for removal of formaldehyde

Hossein Khaleghi,Hossein Esmaeili,Neamatollah Jaafarzadeh,Bahman Ramavandi 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.1

Activated carbon (AC) was produced from date seeds by a calcination process at 700 oС for 2 h and then its surface was improved with CaO and magnetic nanoparticles. AC/CaO/Fe3O4 nanocomposite was then employed to remove formaldehyde ions from aqueous media. The structural characteristics of the materials were completely studied through FT-IR, XRD, SEM, EDX, Map, VSM, BET and TEM analyses. The results showed that the nanocomposite has a mesoporous structure (average pore diameter~13 nm) with great sorption capability. Also, the utmost removal efficiency of formaldehyde using AC, AC/Fe3O4, CaO/Fe3O4 and AC/Fe3O4/CaO nanocomposite was 94.73, 95.67, 95.14 and 98.22%, respectively, indicating that the removal efficiency increases by improving the surface properties of the AC. Moreover, the uptake of formaldehyde using AC/Fe3O4/CaO nanocomposite follows the Freundlich isotherm and pseudo-2nd-order kinetic models. Furthermore, the highest sorption capacity of AC, AC/Fe3O4, CaO/Fe3O4 and AC/ Fe3O4/CaO nanocomposite using the Langmuir model was obtained 19.86, 24.21, 21.28 and 24.01mg/g, respectively. The thermodynamic study showed that formaldehyde sorption using all four adsorbents is exothermic and spontaneous. The reusability of the adsorbents was also evaluated after ten reuse cycles and the outcomes indicated that these four adsorbents have significant reusability. Moreover, the impact of interfering ions (e.g., carbonate, sulfate, phosphate, nitrate and chloride) showed that all of these compounds, except nitrate, had little competition with formaldehyde ions for adsorption on the nanocomposite surface.

Neighbourhood morphology, genuine self-expression and place attachment, the case of Tehran neighbourhoods

Hossein Khosravi,Hossein Bahrainy,Shadi Omidvar Tehrani 서울시립대학교 도시과학연구원 2020 도시과학국제저널 Vol.24 No.3

In this paper, the neighbourhood’s morphology has been evaluated according to socio-behavioural aspects and sense of place. It seems that place attachment, social bonding, and total time residents spent in local spaces are highly determined by neighbourhood’s socio-behavioural dimensions, and in turn, neighbourhood’s morphological attributes have a great impact on socio-behavioural dimensions. To verify the hypothesis, 843 participants have been selected through Neyman allocation modelling from 5 morphologically representative neighbourhoods. The built-environment attributes were gathered through an objective method (GIS). Sense of place, meantime residents, spent in public spaces, socio-behavioural indicators, and a number of socio-demographic characteristics were collected by self-administered questionnaires. According to our analysis, high and middle-rise neighbourhoods, with low coverage massing, by providing plenty of wide, non-hierarchical, and inter-connected spaces, could ensure personal privacy, anonymity, and consequently autonomy, genuineness, and tendency to use neighbourhood spaces. In contrast, historic organic neighbourhoods with narrow hierarchical pathways and massing alongside them increase the level of social monitoring and conformity. Thus, policies that support mixed-use, connected street networks, plenty of shared open spaces, non- hierarchical network patterns, and smaller block sizes can be used by urban designers to promote neighbourhoods supporting residents’ psycho-social preferences.

In Situ Formation of Extremely High Corrosion Resistant Ni–Ni3Si Nanocomposite Coating Using Spark Plasma Sintering and Subsequent Heat Treatment

Hossein Hassannejad,Ashkan Nouri,Mohammad Hossein Assari,Seyed Hani Mirfalah,Mansour Bozorg 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.3

In this study, the coating of Ni–Ni3Si nanocomposite was produced in-situ on plain carbon steel using spark plasma sinteringprocess of Ni and Si powders followed by heat treatment. Increasing Si content in the powders from 6 to 13 wt% increasedthe amount of Si in the coatings (from 5.1 to 11.8 wt%). The corrosion behavior of the coated samples in 1 M sulfuric acidsolution was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy techniques. In the 13wt% Si coating, the eutectic structure consisting of the Ni and Ni3Siphases was observed to be uniformly distributed. Ni3Sinanoparticles with an approximate size of 90 nm were obtained in the coating by heat treatment. The results showed thatpassive behavior is obtained by heat treatment due to the uniform distribution of Ni3Sinanoparticles and also the uniformdiffusion of silicon into the nickel phase. The excellent passivation results in the highest corrosion resistance in 13 wt%Sicoating after the heat treatment.

High Velocity Impact Response of Aluminum- Carbon Fibers-Epoxy Laminated Composites Toughened by Nano Silica and Zirconia

Hossein Rahmani,Reza Eslami-Farsani,Hossein Ebrahimnezhad-Khaljiri 한국섬유공학회 2020 Fibers and polymers Vol.21 No.1

This research work investigated the effects of SiO2 and ZrO2 nanoparticles type and content incorporated into anepoxy matrix on the high velocity impact behavior of carbon fiber reinforced aluminum laminates (CARALL). CARALLspecimens consisted of a 0/90/90/0 stacking sequence of a carbon-epoxy composite containing 0, 1, 3, 5 and 7 wt% of each ofnanoparticles sandwiched between two layers of aluminum 2024-T3. To observe the toughening effects of the nanoparticleson the fracture surface of the impacted CARALL, a typical field emission scanning electron microscope (FESEM) wasemployed. Impact energy absorption of CARALL was at most increased by 18 % and 12 % with the nanoparticles content of5 wt% SiO2 and 3 wt% ZrO2, respectively. Overloading of the nanoparticles content up to 7 wt% resulted in the creation ofnanoparticles aggregated sites associated with loss in the energy absorption capacity. FESEM fractography procedure alsoshowed that the crack deflection and pinning were the most recognizable toughening mechanisms exhibited by nanoparticles. Overall, the controlled addition of SiO2/ZrO2 rigid nanoparticles to CARALL was found to be a promising method forimproving the high velocity impact energy absorption of CARALL.

Novel Method of ACO and Its Application to Rotor Position Estimation in a SRM under Normal and Faulty Conditions

Hossein Torkaman,Ebrahim Afjei,Hossein Babaee,Peyman Yadegari 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.6

In this paper a novel method of the Ant Colony Optimization algorithm for rotor position estimation in Switched Reluctance Motors is presented. The data provided by the initial assumptions is one of the important aspects used to solve the problems relative to an Ant Colony algorithm. Considering the nature of a real ant colony, it was found that the ants have no primary data for deducing which is the shortest path in their initial iteration. They also do not have the ability to see the food sources at a distance. According to this point of view, a novel method is presented in which the rotor pole position relative to the corresponding stator pole in a switched reluctance motor is estimated with high accuracy using the active and inactive phase parameters. This new method gives acceptable results such as a desirable convergence together with an optimized and stable response. To the best knowledge of the authors, such an analysis has not been carried out previously.

Intrinsic kinetics of the Fischer-Tropsch synthesis over an impregnated cobalt-potassium catalyst

Hossein Atashi,Mohsen Mansouri,Seyyed Hossein Hosseini,Mohammad Khorram,Ali Akbar Mirzaei,Masoud Karimi,Ghobad Mansouri 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.3

The optimal amount of 15 wt%Co/10 wt%K/Al2O3 catalyst was prepared using the impregnation technique in order to study the kinetics of the Fischer-Tropsch synthesis. The rate of synthesis was measured in a fixed-bed micro reactor with H2/CO feed ratio of 1-3 and space velocity in the range of 2,700-5,200 h−1 under reactor pressure of 8 bar and a temperature range of 210-240 oC. The experimental data were best fitted by a Langmuir-Hinshelwood-Hougen-Watson (LHHW) approach rate in the form of −rCO=(k2K1PCOPH2)/(1+K1PCO). Furthermore, the data were fitted fairly well by a power law equation in the form of −rCO=kPCO 1.32PH21.42. The activation energies for LHHW approach model and power law equation were obtained as 138.5 kJ/mol and 87.39 kJ/mol, respectively.