Harmonic Optimization Techniques in Multi-Level Voltage-Source Inverter with Unequal DC Sources

Aghdam, M. Ghasem Hosseini,Fathi, S. Hamid,Gharehpetian, Gevorg B. The Korean Institute of Power Electronics 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.2

One of the major problems in electric power quality is the harmonic contents. There are several methods of indicating the quantity of harmonic contents. The most widely used measure is the total harmonic distortion (THD). Various switching techniques have been used in static converters to reduce the output harmonic content. This paper presents and compares the two harmonic optimization techniques, known as optimal minimization of the total harmonic distortion (OMTHD) technique and optimized harmonic stepped-waveform (OHSW) technique used in multi-level inverters with unequal dc sources. Both techniques are very effective and efficient for improving the quality of the inverter output voltage. First, we describe briefly the cascaded H-bridge multi-level inverter structure. Then, we present the switching algorithm for the inverter based on OHSW and OMTHD techniques. Finally, the results obtained for the two techniques are analyzed and compared. The results verify the effectiveness of the both techniques in multi-level voltage-source inverter with non-equal dc sources, clarifying the advantages of each technique.

Awareness and Attitude of Nurses in Regard to Providing Hospice Care

Aghdam, Alireza Mohajjel,Aghaei, Mir Hossein,Hassankhani, Hadi,Rahmani, Azad Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.16

Background: Awareness and attitudes of nurses regarding end of life care are important factors in providing hospice care. In an extensive literature review, we found no related articles investigating Iranian nurses awareness and attitudes about providing such care. Objectives: The aims of this study were to investigate the awareness and attitudes of Iranian nurses in providing hospice care. Materials and Methods: In this descriptive-correlational study, 240 nurses employed in six educational centers were selected by non-randomized stratified sampling. The data collection instruments included an awareness test and attitudes regarding providing end of life care in hospice questionnaire. The data were analyzed using descriptive statistics and independent sample t-tests, one-way ANOVA, and Pearson correlation tests. Results: The nurses' awareness score was 14.3 out of 29 and 55.7% of them stated that they had not received any education in providing end of life care. Also, by obtaining the score of 91.7 out of 120 the attitudes of participants in providing end of life care in hospices were positive. In addition, the highest attitudes score of nurses were in the dimensions of benefits of implementation and health care team. Conclusions: Considering low awareness of nurses about end of life care in hospices, continuing education should be provided for them in this regard. Especially, by considering the positive attitude of nurses, providing such programs could help develop hospice care in Iran.

Z-Source Inverter with SiC Power Semiconductor Devices for Fuel Cell Vehicle Applications

Aghdam, M. Ghasem Hosseini The Korean Institute of Power Electronics 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.4

Power electronics is a key technology for electric, hybrid, plug-in hybrid, and fuel cell vehicles. Typical power electronics converters used in electric drive vehicles include dc/dc converters, inverters, and battery chargers. New semiconductor materials such as silicon carbide (SiC) and novel topologies such as the Z-source inverter (ZSI) have a great deal of potential to improve the overall performance of these vehicles. In this paper, a Z-source inverter for fuel cell vehicle application is examined under three different scenarios. 1. a ZSI with Si IGBT modules, 2. a ZSI with hybrid modules, Si IGBTs/SiC Schottky diodes, and 3. a ZSI with SiC MOSFETs/SiC Schottky diodes. Then, a comparison of the three scenarios is conducted. Conduction loss, switching loss, reverse recovery loss, and efficiency are considered for comparison. A conclusion is drawn that the SiC devices can improve the inverter and inverter-motor efficiency, and reduce the system size and cost due to the low loss properties of SiC devices. A comparison between a ZSI and traditional PWM inverters with SiC devices is also presented in this paper. Based on this comparison, the Z-source inverter produces the highest efficiency.

Approaching Green Buildings Using Eco-Efficient Construction Materials: A Review of the state-of-the-art

Aghdam, Karim Aligholizadeh,Rad, Alireza Foroughi,Shakeri, Hamed,Sardroud, Javad Majrouhi Korea Institute of Construction Engineering and Ma 2018 Journal of construction engineering and project ma Vol.8 No.3

Since the protection the of human being from natural disaster and atmospheric factors have become an essential requirement, some attempts have been taken place to provide shelter and create a safe environment to a more comfortable life with welfare. For this purpose, using existing resources in nature and exploiting them in a different manner have been taken into account. Initially, the performed exploitations for construction had the least damage to the environment, but over time and as a result of population growth, aggressive exploitation of nature has led to destroying effects on the environment and resulted in consequences such as pollution and environmental destruction. Thus, the construction industry has been identified as the top pollutant factors of the environment. Among various construction factors, the building materials used in this industry are considered as the most important effective factors on the environment, as they have direct influences on the environment from the beginning of construction of the final steps. This research focuses on the review of the most of the existing green materials definitions and various approaches towards using eco-efficient construction materials. It presents and discusses possible ways of reducing the destructive effects on the environment by selecting and using green materials, review current literature and highlight the necessity of applying such materials in future constructions in all communities. This paper provides a base for this purpose that sustainable development communities and environment is realized by elimination of environmental pollution and approaching the criteria of green building by using sustainable materials.

Investigation of Association between oipA and iceA1/iceA2 Genotypes of Helicobacter pylori and Gastric Cancer in Iran

Aghdam, Saeed Mahboubi,Sardari, Zeinab,Safaralizadeh, Reza,Bonyadi, Mortaza,Abdolmohammadi, Reza,Moghadam, Mostafa Soltani,Khalilnezhad, Ahad Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.19

Background: H pylori is the main causative agent of Gastric cancer and chronic gastritis. Genetic diversity of H. pylori has major contribution in its pathogenesis. We investigated the prevalence of oipA and iceA1/iceA2 positive strains of H. pylori among patients with gastric cancer and gastritis. Materials and Methods: Sampling performed by means of endoscopy from 86 patients. DNA was extracted from tissue samples using DNA extraction kit. PCR assay was performed and products were monitored by Agarose Gel Electrophoresis. Results: Urease Test and 16S rRNA PCR did not show significant differences in detection of H. pylori. The frequency of iceA1 allele in patients with gastric cancer was significantly higher than those with gastritis (p<0.05). However, there was no significant difference in prevalence of oipA and iceA2 genes among the two groups of patients (p>0.05). Conclusions: The iceA1 gene, but the oipA and iceA2 genes, is associated with H. pylori-induced gastric cancer. However, confirmatory studies must be performed in future.

Nitrogen assessment by remote sensing and multispectral imagery in maize (Zea mays L.)

Jaberi-Aghdam Mehryar,Momayezi Mohammad Reza,Bagheri Nikrooz,Azizi Peyman,Nasri Mohammad 한국작물학회 2024 Journal of crop science and biotechnology Vol.27 No.1

Over-application of nitrogen fertilizers in farm lands is the main reason to contaminate nitrogen components in the environment. Nitrogen can play a main role on the plant growth, biomass and crop yield. Therefore, the aim of this study was to evaluate diferent nitrogen rates and the response of maize plant characteristics on some vegetative indices using aerial multispectral imaging. The study was carried out in an experimental farm in Varamin city (35.80°N, 51.40°E), Tehran province, Iran. The experiment was performed in Randomized Complete Block Design (RCBD) with four treatments and two sampling stage in four replications. The treatments were diferent nitrogen rates included none (as control), 250, 500 and 750 kg urea ha−1 fertilizer which was applied by irrigation water and two sampling stage, 8-leaf stage (V8) and tasseling stage. Data analysis based on the diferent growth stages showed that, there were signifcantly increased in the average plant height (198 cm), total dry weight (336.73 g), SPAD index, and leaf nitrogen content in both V8 and tasseling stage. Based on our results, in the V8 growth stage chlorophyll index, modifed triangle vegetation index (MTVI), and green model index with the correlation coefcients 0.88, 0.86, and 0.80, respectively, were the most suitable indicators for detecting nitrogen stress in this edaphic and climatic conditions for this plant. Generally, it can be concluded that chlorophyll index in the V8 growth stage and nitrogen refectance index (NRI) in the tasseling growth stage are the most appropriate indicators for detecting nitrogen stress in that studied area. As a result, aerial multispectral imaging is a reliable technology to assist farmers in fertilizing plants at the right time and place, as well as the amount that the plants need. So, this technology is in accordance with the precious agriculture’ goals and eco-friendly

Photocatalytic removal of NOx over immobilized BiFeO3 nanoparticles and effect of operational parameters

Taher Rahimi Aghdam,Habib Mehrizadeh,Dariush Salari,Hui-Hsin Tseng,Aligholi Niaei,Azam Amini 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.4

Perovskite type BiFeO3 (BFO) was synthesized by sol-gel auto-combustion method. Synthesized BFO was immobilized on the micro slides glass plates by sol-gel dip-coating method. The sample was characterized by XRD, FESEM, UV-Vis DRS, and BET techniques. The XRD pattern confirmed the perovskite structure, and from the Debye- Scherrer equation the average crystalline size was calculated as 19 nm. The FE-SEM images of prepared BFO showed porous structure with low agglomeration. The band gap energy was calculated about 2.13 eV, and the specific surface area (SSA) of prepared BFO nanostructure was obtained 55.1m2 g1. The photocatalytic activity of prepared pure and immobilized BFO was investigated in the removal of NOx under UV irradiation, in the batch photoreactor. The effects of operational parameters such as initial concentration of NOx, light intensity and amount of coated photocatalyst, under identical conditions, were investigated. The results showed that the highest conversion of NOx was obtained as 35.83% in the 5 ppm of NOx with 1.2 g immobilized BFO and under 15 W illumination lamp.

Harmonic Optimization Techniques in Multi-Level Voltage-Source Inverter with Unequal DC Sources

M. Ghasem Hosseini Aghdam,S. Hamid Fathi,Gevorg B. Gharehpetian 전력전자학회 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.2

One of the major problems in electric power quality is the harmonic contents. There are several methods of indicating the quantity of harmonic contents. The most widely used measure is the total harmonic distortion (THD). Various switching techniques have been used in static converters to reduce the output harmonic content. This paper presents and compares the two harmonic optimization techniques, known as optimal minimization of the total harmonic distortion (OMTHD) technique and optimized harmonic stepped-waveform (OHSW) technique used in multi-level inverters with unequal dc sources. Both techniques are very effective and efficient for improving the quality of the inverter output voltage. First, we describe briefly the cascaded H-bridge multi-level inverter structure. Then, we present the switching algorithm for the inverter based on OHSW and OMTHD techniques. Finally, the results obtained for the two techniques are analyzed and compared. The results verify the effectiveness of the both techniques in multi-level voltage-source inverter with non-equal dc sources, clarifying the advantages of each technique.

Z-Source Inverter with SiC Power Semiconductor Devices for Fuel Cell Vehicle Applications

M. Ghasem Hosseini Aghdam 전력전자학회 2011 JOURNAL OF POWER ELECTRONICS Vol.11 No.4

Power electronics is a key technology for electric, hybrid, plug-in hybrid, and fuel cell vehicles. Typical power electronics converters used in electric drive vehicles include dc/dc converters, inverters, and battery chargers. New semiconductor materials such as silicon carbide (SiC) and novel topologies such as the Z-source inverter (ZSI) have a great deal of potential to improve the overall performance of these vehicles. In this paper, a Z-source inverter for fuel cell vehicle application is examined under three different scenarios. 1. a ZSI with Si IGBT modules, 2. a ZSI with hybrid modules, Si IGBTs/SiC Schottky diodes, and 3. a ZSI with SiC MOSFETs/SiC Schottky diodes. Then, a comparison of the three scenarios is conducted. Conduction loss, switching loss, reverse recovery loss, and efficiency are considered for comparison. A conclusion is drawn that the SiC devices can improve the inverter and inverter-motor efficiency, and reduce the system size and cost due to the low loss properties of SiC devices. A comparison between a ZSI and traditional PWM inverters with SiC devices is also presented in this paper. Based on this comparison, the Z-source inverter produces the highest efficiency.

Comparison of OMTHD and OHSW Harmonic Optimization Techniques in Multi-Level Voltage-Source Inverter with Non-Equal DC Sources

M. G. HOSSEINI AGHDAM,S. H. FATHI,G. B. GHAREHPETIAN 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-

One of the major problems in electric power quality is the harmonic contents. There are several methods of indicating the quantity of harmonic contents. The most widely used measure is the total harmonic distortion (THD). This paper compares the two harmonic optimization techniques, optimal minimization of the total harmonic distortion (OMTHD) technique and optimized harmonic stepped-waveform (OHSW) technique used in multi-level voltage-source inverters. Both techniques are very effective and efficient for improving the quality of the inverter output voltage. First, we describe briefly the cascaded H-bridge multi-level inverter structure. Then, we present the switching algorithm for the inverter based on OHSW and OMTHD techniques. Finally, the results obtained by simulation for the two techniques are analyzed and compared. Simulation results verify the effectiveness of the both techniques in multi-level voltage-source inverter with non-equal DC sources, clarifying the advantages of each technique.