p amiri

Renewable energy, like wind turbines, is growing rapidly in the world today due to environmental pollution, so their maintenance plans are very important. Fault diagnosis and fault-tolerant approaches are typical methods to reduce the cost of energy production and downtime of Wind Turbines (WTs). In this paper, a new Hardware In the Loop (HIL) simulator based on Double Feed Induction Generator (DFIG) for fault diagnosis and fault-tolerant control is proposed. The system developed as a laboratory bed uses a generator with a power of about 90 kW, which is connected from two sides to a back-to-back power converter with a power of one-third of the generator power. The generator is connected to a motor as a propulsion and wind energy replacement with a power of about 110 kW, and this connection is established through a gearbox with a gear ratio of more than three. The effectiveness of the proposed simulator is evaluated based on different fault representations back-to-back converter and generator. The experiment shows that the Condition Based Maintenance (CBM) is improved by the proposed simulator and the fault is modeled before serious damage occurs. This setup is effective for the development of wind turbine fault analysis software. As the testing on real WTs is very expensive, to improve and develop the research fields of condition monitoring and WT control, this low-cost setup is effective.

Many applications use boost converters as front-end circuits, including power factor correction (PFC), solar power generation, fuel cell power conversion, battery chargers, and uninterruptible power supply. In addition, boost converters have a simple structure with low component counts, which makes them a convenient choice. This article proposes a coupled-inductor active auxiliary circuit to create a new low-stress boost converter with soft-switching. The proposed auxiliary circuit supplies the main switch and diode with soft-switching ZVC turn-on and ZCS turn-off states. The main switch and diode are not deal with any extra stress of voltage or current. Furthermore, the soft switching condition is also provided for auxiliary circuit components. The proposed auxiliary circuit also has a simple structure, low circulating current losses, low cost, and simplicity in control. The operation state and performance of the proposed soft-switching boost converter are examined, and the design procedure is presented. Finally, a 200W prototype is implemented and tested to validate the theoretical results. The offered experimental data verified the theoretical analysis. This paper provides a new low-stress soft-switching boost converter using a simple coupled-inductor in the auxiliary circuit. Moreover, the auxiliary part consists of two diodes, one switch, one resonance capacitor, and a coupled inductor. The suggested auxiliary circuit provides soft switching condition for the main switch, which provides ZVS in the turn-on transient and ZCS in the turn-off transient, while in this situation, the soft-switching condition is provided for the auxiliary switch, which turns on under ZCS and also turns off with practically ZVS conditions. The auxiliary circuit does not impose additional voltage or current stress on the main switch. A 200 W prototype is implemented to validate the performance of this snubber cell. The experimental data reported here support the theoretical analysis. The best point of efficiency is 95.9% which is occurred at maximum load, and is 6.3% greater than the traditional counterparts.

The Covid-19 and the imposed restrictions, along with difficulty in accessing medical services, can affect the level of anxiety, stress, and depression of patients with diabetes. This study was conducted to determine the effect of the Covid-19 pandemic on the emotional status of these patients. A total of 318 individuals with type 2 diabetes who participated in the Tehran Lipid and Glucose Study between 2018 and 2020 were included in the current study. The data on perceived social support (PSS) and emotional state (ES) were collected before and after the Covid-19 outbreak using the multidimensional scale of perceived social support (MSPSS) and Depression, Anxiety, and Stress Scale-21 Items (DASS-21) questionnaires, respectively. Data were analyzed using paired T-tests and repeated measures tests. Mean total scores of PSS did not have significant differences before and after the outbreak of Covid-19. Comparison of the subscale scores indicates a significant increase in PSS from family (p=0.013) and a significant decrease in PSS from friends (p=0.039) in women, and an increase in PSS from significant others in both groups of women (p=0.019) and men (p=0.045). Comparing the ES scores before and after the outbreak of Covid-19 indicated that the adjusted model, anxiety, and stress scores decreased significantly after the Covid-19 outbreak in females. There was no significant difference in anxiety and stress scores in males and depression scores in both sexes. After the outbreak of Covid-19, levels of anxiety and stress in women have decreased, which can be due to the improvement of PSS from the family and, consequently, the reduction of diabetes-related concerns.

Adopting diabetes self-care behaviors to control blood glucose is essential, but adherence to them has been challenged due to restrictions related to Covid-19. These restrictions have negatively impacted the psychosocial condition of individuals with diabetes, which could lead to poor self-care. Accordingly, this study aimed to explore the experiences of individuals with type 2 diabetes regarding self-care behaviors and diabetes management during the COVID-19 pandemic.

This qualitative study was conducted using conventional content analysis, the data of which were collected through interviews with people over 18 years of age with type 2 diabetes who were selected from the Endocrinology Clinic of Erfan Hospital in Tehran. Using telephone and WhatsApp, semi-structured interviews were conducted with 20 participants (15 women). Content analysis was done using the constant comparative method, and the open and axial coding method was applied. The data were manually coded, and the main themes and categories emerged from data.

Two main themes emerged from the data: 1) challenges and limitations toward diabetes self-care and 2) facilitators of efficient self-care. Challenges and limitations included 4 sub-themes: Inevitable lifestyle changes, psychosocial problems, limited/lack of access to health care services and medication, and adverse physical effects. Facilitators had 2 sub-themes: improved individual capability and maintaining social interaction.

Our findings indicated that inevitable lifestyle changes, limited access to health care, and adverse psychosocial consequences were the most critical challenges for diabetes management during the COVID-19 pandemic. Improving stress management skills and effective coping strategies can facilitate the adoption of self-care behaviors.

The potential relationship between thyroid dysfunction with common psychological problems (i.e., depression, anxiety, and stress), and health-related quality of life (HRQoL) has been discussed in the literatures. However, previous studies have mostly addressed overt hypo-hyper thyroid patients, and it has been limited to hypothyroidism in Iranian population. The novelty of this study is investigating the same relationship using the most up-to-date and reliable questionnaires among Iranian adults with overt and subclinical hypo- and hyper- thyroid dysfunctions compared to euthyroid individuals.

In this cross-sectional study, the participants were selected randomly from patients referred to the endocrinology clinic. In this regard, 212 patients were selected regarding inclusion and exclusion criteria and categorized into hypofunctional (subclinical and overt hypothyroidism), hyperfunctional (subclinical and overt hyperthyroidism), and euthyroid groups. The participants’ emotional states and HRQoL were assessed using the 21-item Depression, Anxiety, and Stress Scale (DASS-21) and the Short-Form 12-point Health Survey Version 2 (SF-12v2). The collected data was analyzed with the SPSS software version 22.

 The results indicated that those with thyroid dysfunction in both hypofunctional and hyperfunctional groups had significantly higher levels of depression, anxiety, and stress symptoms (p<0.05) and lower HRQoL than their euthyroid counterparts. However, a more detailed analysis showed that the physical and mental domains of HRQoL were mainly affected in the participants with hyper- and hypo-functional dysfunction, respectively.

 The present findings revealed that thyroid dysfunction could lead to negative emotional states in adult populations. Similar findings have been achieved for HRQoL in different aspects.

One of the major faults in Doubly-Fed Induction Generator (DFIG) is the Inter-Turn Short Circuit (ITSC) fault. This fault leads to an asymmetry between phases and causes problems to the normal state between current lines. Faults diagnosis from non-stationary signals for the Wind Turbine (WT) is difficult. Therefore, the strategy of fault diagnosis must be robust against instability. In this paper, a new intelligent strategy based on multi-level fusion is proposed for diagnosis of DFIG inter-turn stator winding fault. Firstly, to overcome the non-stationary nature of the vibration signals of the WT, empirical mode decomposition (EMD) method is performed in time-frequency domains to extract best fault features from information power sensor and information current sensor. Moreover, a feature evaluation technique is used for the input of the classifier to choose the best subset features. Secondly, Least Squares Wavelet Support Vector Machines (LS-WSVM) classifier is trained to classify fault types based on feature level fusion (FLF) from different sensors. The main parameters of SVM and the kernel function are optimized by Genetic Algorithm (GA). Finally, Dempster-Shafer evidential reasoning (DSER) is used for fusing the GA-LS-WSVM results based on decision level fusion (DLF) of individual classifiers. In order to evaluate the proposed strategy, a DFIG WT test rig is developed. The experimental results show the efficiency of the proposed structure compared to other ITSC fault diagnosis methods. The results show that the classification accuracy of DSER-GA-LS-WSVM is 98.27%.

Iron aluminide intermetallic compound, including compounds that have great features is that it's so great properties, due to its increasing use in industry is different. In thiswork, structural and dynamic properties of FeAl compounds including the structure of energybands, density of states, phonon and thermal properties in two-phase structures regularly evaluated and calculated. Calculations using a Pseudoptential, within the framework of density functional theory have been studied PWscf code. The study found that the combination of these features in your base has a metal in ferromagnetic order, the results of the electronicstructure of this compound are indicative of metal and the structure of the electron cloud indicates the ionic bond -covalent for two phases results in good agreement with the experimental results are available.

Due to the increased sensitive loads, improving power quality in distribution grids by custom power tools is one of the important fields of electrical engineering. This paper proposes a new kind of three-phase three-wire dynamic voltage restorer (without including storage sources or DC link) and also its control method.

The proposed structure includes an AC/AC converter, low-pass filters at the input and output sides, and three-phase injection transformers. The control system is based on the combination of feedback and feedforward control that its advantages are high speed, good response quality, and very simple implementation. To overcome the harmonics raised from AC/AC converter switching on the main line, a SOGI-PLL has been used. Also, SOGI-PLL operates independently on each phase so that the asymmetric voltage variations can be identified.

The proposed control method is capable to compensate the power quality problems such as voltage sag, swell, and harmonics in balanced and unbalanced conditions. The detailed modelling and design of the proposed controller are verified through computer simulations and experimental results under different operating conditions. Simulation and experimental results show that the proposed control strategy can compensate the power quality events as close as possible to the desired values under different operation modes.

In this paper, a three-phase three-wire dynamic voltage restorer (DVR) was assessed using direct AC/AC converters without a supply source and DC link. A control system based on combined feedback and feedforward control (CFBFFC) and SOGI-PLL has been proposed for the DVR. The simulation results on a three-phase 20kV system as well as the experimental results obtained from a single-phase 220V system verified the performance of the DVR and the control system. It was shown that this structure can compensate for 0.5pu voltage sag, above 1pu voltage swell, and all kinds of harmonic faults.

In this paper the elastic, mechanical (stability, anisotropy and Poisson's coefficients) and acoustic properties of BeX (X= S, Se, Te) have been investigated. Calculations with Full potential linear augmented plane wave have been performed in the framework of density functional theory with LDA, PBE-GGA and MBJ approximations by using Wien2k computational package. Elastic properties such as, elastic constants, Shear modulus, Young modulus and Debye temperature were calculated within various approximations for cubic and hexagonal structural phases. The calculated elastic properties indicate the give rise to an elastic stability and anisotropy property of the compounds. The results also indicate that these compounds are more brittle in the cubic phase and more malleable in the hexagonal phase. In fact, the ductility of these compounds in the cubic structural phase is low and they can be placed in the category of non-formable materials.

In this paper, the phonon, dynamic and thermal properties of indium nitride in two phases are investigated. The calculations are performed using the pseudopotantial method in the framework of density functional theory and by using the quantum-espresso Package. In the calculations, the exchange-correlation terms of LDA, GGA and PBE0 approximation are used. Investigation of phononic  properties shows that in this combination in the two phases Wz and Zb there is a frequency gap. From the study of thermal properties we find that the heat capacity drop is at low temperatures is as follos T3. At high temperatures, the heat capacity is also close to the Dulan-Petty law.The results from the phonon spectrum indicate that from the frequency of 209. 885 to 453 .112 cm -1 there is no acoustic and optical phonon modes and the most stable phase; Phase is the Wz.

In this paper, a new design strategy was proposed in order to enhance bandwidth and efficiency of power amplifier.

To realize the introduced design strategy, a power amplifier was designed using TSMC CMOS 0.18um technology for operating in the Ka band, i.e. the frequency range of 26.5-40GHz. To design the power amplifier, first a power divider (PD) with a very wide bandwidth, i.e. 1-40GHz, was designed to cover the whole Ka band. The designed Doherty power amplifier consisted of two different amplification paths called main and auxiliary. To amplify the signal in each of the two pathways, a cascade distributed power amplifier was used. The main reason for combining the distributed structure and cascade structure was to increase the gain and linearity of the power amplifier.

Measurements results for designed power divider are in good agreement with simulations results. The simulation results for the introduced structure of power amplifier indicated that the gain of proposed power amplifier at the frequency of 26-35GHz was more than 30dB. The diagram of return loss at the input and output of power amplifier in the whole Ka band was less than -8dB. The maximum Power Added Efficiency (PAE) of the designed power amplifier was 80%. The output p 1dB of the introduced structure was 36dB, and the output power of power amplifier was 36dBm. Finally, the IP3 value of power amplifier was about 17dB.

The strategy presented in this paper is based on usage of Doherty and distributed structures and a new wideband power divider to benefit from their advantages simultaneously. The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, as long as the original authors and source are cited. No permission is required from the authors or the publishers.

Preparation of root canal with rotary nickel-titanium (NiTi) instruments may potentially create microcracks that can lead to vertical root fracture. This study aimed to compare the incidence of crack formation by BioRaCe and Edge Taper Platinum systems in the mesiobuccal canals of extracted first mandibular molars.

In this experimental study, 50 first mandibular molars, which met all the inclusion criteria, with a canal curve of 25-35 degrees, were selected and randomly divided into two groups of 24. Each specimen was mounted in a resin block and a thin layer of silicone impression to simulate the periodontal ligament (PDL) while the apex was exposed. Group A was prepared by BioRaCe, and group B was prepared by Edge Taper Platinum. Two teeth were left unprepared and served as the control. The roots were sectioned horizontally at 3, 6, and 9mm from the apex and evaluated under a stereomicroscope at ×20 magnification. The presence of dentinal defects was examined and analyzed using Mann-Whitney test.

BioRaCe rotary files showed more cracks (47.3%) than Edge Taper Platinum (19.5%) at all three levels with a significant difference (P=0.038). No statistically significant difference was found between these two systems at the coronal (9mm from the apex) and apical (3mm from the apex) levels but a significant difference was found between BioRaCe and Edge Taper Platinum in the midroot (6mm from the apex; P=0.014).

It seems that the Edge Taper Platinum system causes fewer cracks in curved dentinal walls compared to the BioRaCe system.

In this paper, a digital pseudo-differential Schmitt trigger with very low supply voltage is proposed. The proposed Schmitt trigger is design by exploiting the design procedure of an analog Schmitt trigger. It is implemented only using digital CMOS inverters which is composed of a pseudo-differential comparator consisting of two CMOS inverters and a cross-coupled inverter pair as positive feedback. The proposed circuit is the only digital Schmitt trigger which operates in fully-differential mode that has simultaneously two outputs of non-inverting and inverting and its hysteresis center can be changed by the input voltage. The proposed Schmitt trigger is simulated in 0.18 um CMOS process with 0.4 V supply voltage. Due to the very low number of transistors, the proposed circuit occupies 10×9.8 μm2 chip area and consumes only 6.64 nW power.

Heavy metals enter to water resources through various ways, causing dangers such as illness, cancer, and, in general, a disorder in the body of living organisms. Mullet (Liza aurata) is highly consumed by the people living in Guilan province, Iran. Therefore, the amount of heavy metals included copper, zinc, and nickel was investigated in the muscle tissue of mullet. A total number of 11 mullet were obtained from Bandar Anzali.  After a preparation step, the fish samples were digested using chemical digestion, and the amounts of heavy metals were determined by atomic absorption. The average concentration of copper, zinc, and nickel in muscle tissue was 10.07±0.93, 28.39 ±3.99, and 4.01 ± 0.55 μg/g dry weight, respectively. The concentrations of the studied metals were lower than the FAO, WHO, FDA, NHMRC and UKMAFF international standards, except for the nickel. The daily absorption rates of the studied metals (EDI) for children and adults were lower than the reference dose set by the EPA and the TI provided by the FAO / WHO Organization. The risk potential (THQ) of seven days, three days and one day consumption per week of Golden grey mullet for both adults and children were found less than 1. The hazard index (HI) of 7 days a week consumption of mullet for children was greater than 1. According to the results of the present study, the consumption of this fish has a harmful effect on consumer health in children age group.

Given the many applications of half-metals in the spintronics devices, we investigated the half-metallic properties of the KP compound in rock-salt (RS) and cesium chloride (CsCl) structural phases by using density functional theory. The results indicated that the KP compound as the half-metal in the RS structure, in contrast to the CsCl structure, due to the small lattice constant and failure of Stoner criterion, did not have any magnetic properties. Half-metallic gap value obtained was remarkable for the RS structure. Although the KP compound in the CsCl structure was more stable than the RS structure energetically, from a dynamical point of view, the RS structure was stable and the CsCl structure was unstable. Calculations corresponding to the (001) surface of the RS structure also demonstrated the conservation of the bulk half-metallic properties in this crystallographic direction. So, the nano-layers of the KP compound in the RS structure might be an appropriate candidate for application in the near future spintronics devices.

There are significant correlations between the mental health status of individuals and non-communicable mental or physical diseases. Epidemiological data regarding mental health indices plays an important part in the planning and designing of mental health programs. This study was conducted to evaluate the general mental health status of inhabitants in an area of Tehran as part of the TLGS.

In this cross-sectional study, 927 residents (20 years and older) of a specific area were randomly selected. Subjects completed the demographic data forms alongwith the General Health Questionnaires (GHQ), validated for the Iranian population. A cut off of 6 and above was used as threshold to identify the group suspected of having psychiatric disorders. To compare the scores of total GHQ and subscales between different demographic variables, the Chi square, Mann whitney and Kruskal wallis test were used. Logistic regression was used to identify variables related to the group that scored above threshold.

The total sample studied consisted of 927 adults, of whom 401 (43.3%) were males and 526 (56.7%) females. Among them 489 (52.8%) were suspected of having psychiatric disorders. Mean score of total GHQ was 7.0±5.4 and regarding the subscales of the questionnaire including physical symptoms, anxiety and sleep disorders, social dysfunction and depression, mean scores were 1.2±1.7, 1.7±2.0, 3.4± 2.0, 0.75±1.4 respectively and the median of mentioned subscales were 0, 1, 3 and 0 respectively. Frequency of women suspected of mental disorders was significantly higher than that of men (59.7% vs. 43.6%, p<0.001).

Taking into consideration the sample group and the method of gathering data, the frequency of those suspected of having psychiatric disorders in our study was higher as compared to other studies. Since mental health plays an important role in health promotion and community development, as well as the financial and psychological burden of illnesses, inplementation of policies in regard to implementation of related programs for prevention especially in women, seems vital.