Likelihood-Based Modulation Classification for Multiple-Antenna Receiver

Ramezani-Kebrya, Ali,Il-Min Kim,Dong In Kim,Chan, Francois,Inkol, Robert IEEE 2013 IEEE TRANSACTIONS ON COMMUNICATIONS Vol.61 No.9

<P>Likelihood-based algorithms for the classification of linear digital modulations are systematically investigated for a multiple receive antennas configuration. Existing modulation classification (MC) algorithms are first extended to the case of multiple receive antennas and then a critical problem is identified that the overall performance of the multiple antenna systems is dominated by the worst channel estimate of a particular antenna. To address the performance degradation issue, we propose a new MC algorithm by optimally combining the log likelihood functions (LLFs). Furthermore, to analyze the upper-bound performance of the existing and the proposed MC algorithms, the exact Cramer-Rao Lower Bound (CRLB) expressions of non-data-aided joint estimates of amplitude, phase, and noise variance are derived for general rectangular quadrature amplitude modulation (QAM). Numerical results demonstrate the accuracy of the CRLB expressions and verify that the results reported in the literature for quadrature phase-shift keying (QPSK) and 16-QAM are special cases of our derived expressions. Also, it is demonstrated that the probability of correct classification of the new algorithm approaches the theoretical bounds and a substantial performance improvement is achieved compared to the existing MC algorithm.</P>

Removal of melanoidin from molasses spent wash using fly ash-clay adsorbents

Ali Ramezani,Ghasem Najafpour Darzi,Maedeh Mohammadi 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.4

Removal of melanoidin pigment from molasses spent wash was investigated using a new adsorbent. Solid adsorbents were fabricated from charcoal fly ash and clay. The effect of various molasses concentration (6 to 12 g/l)on removal efficiency was studied. The obtained results revealed that maximum removal efficiency of 82% was achieved at the molasses concentration of 6 g/l and contact time of 7 h. The saturated porous adsorbents were regenerated and reused to conduct similar experiments. The achieved data showed that more than 90% of the capacity of the fresh adsorbent was recovered after regeneration. Various adsorption isotherms of Langmuir, Freundlich, Temkin and Harkins-Jura were applied to interpret the obtained experimental data. The obtained results revealed that the sorption data were well described by the Harkins-Jura model. Also, various kinetic models of pseudo-first order, pseudo-second order,Elovich and intra-particle diffusion were used to predict the characteristic parameters which are useful in process design. It was concluded that the best fit was obtained with pseudo-second order kinetic model at low molasses concentrations.

Original Articles : Causes of Visual Impairment among Patients Referred to a Visual Rehabilitation Clinic in Iran

( Alireza Ramezani ),( Maasome Pardis ),( Nasrin Rafati ),( Mohsen Kazemi Moghaddam ),( Marzieh Katibeh ),( Pooya Rostami ),( Mohammad Hossein Dehghan ),( Mohammad Ali Javadi ),( Zahra Rabbanikhah ) 대한안과학회 2012 Korean Journal of Ophthalmology Vol.26 No.2

Purpose: Epidemiologic evaluation and investigating the causes of visual impairment in any society is a matter of concern and has a direct effect on the country`s health care planning. In this study we describe causes of low vision and blindness in Iranian patients referred to rehabilitation clinics for taking vision aids. Methods: In this cross-sectional study, visual acuity was classified based on best-corrected visual acuity in the better eye according to the World Health Organization definition (blindness, visual acuity [VA]<20/400; severe visual impairment, VA<20/200-20/400; mild to moderate visual impairment, VA<20/60-20/200). The causes of blindness and low vision were determined using the 10th version of International Classification of Diseases based on the main cause in both eyes. To describe data, we used mean±SD and frequency. Results: The study included 432 patients, 65% male, with a mean age of 43.6±25.5 years (range, 3 to 92 years). Mild to moderate visual impairment, severe visual impairment and blindness were present in 122 (28.8%), 196 (46.4%) and 105 (24.8%) of the patients, respectively. The main causes of visual impairment were retinal and choroidal diseases (74.5%), optic nerve and optic tract diseases (9.8%), vitreous and globe disorders (5.3%), congenital cataract (3.1%), and glaucoma (2.6%). The distribution pattern of the causes was similar in all age subgroups. Conclusions: Diseases of the retina and choroid are the main cause of visual impairment among patients referred to an academic visual rehabilitation clinic in Iran.

Decreasing ICP of forward osmosis (TFN-FO) membrane through modifying PES-Fe3O4 nanocomposite substrate

Rezvaneh Ramezani Darabi,Majid Peyravi,Mohsen Jahanshahi,Ali Asghar Qhoreyshi Amiri 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.8

This film nanocomposite forward osmosis (TFN-FO) membrane was developed using polyethersulfone-ferrous ferric oxide (PES-Fe3O4) nanocomposite substrate. The results revealed that the porosity and the hydrophilicity of the PES substrate were improved after addition of Fe3O4 nanoparticles (NPs), leading to reducing in structural parameter (S value or S) and water flux enhancement. To fabricate TFN membranes for FO application, a thin polyamide layer was fabricated by interfacial polymerization of m-Phenylenediamine (MPD) and 1, 3, 5-trimesoylchloride (TMC) on the top surface of PES-Fe3O4 nanocomposite substrates. The TFN membrane prepared with 0.2 wt% Fe3O4 NPs showing the most reliable results by exhibiting high water flux and low reverse solute flux. Furthermore, TFN0.2 membrane exhibited significantly higher pure water flux than that of control thin film composite (TFC) membrane in both AL-FS and AL-DS orientation when 10 mM NaCl and Caspian seawater was used as feed solution and 0.5 or 2M NaCl was used as draw solution. This improvement can be attributed to the fact that the S value of TFN0.2 is much lower in comparison to control TFC membrane (0.42 vs 0.78 mm), leading to reduced internal concentration polarization (ICP) effect.

Spatiotemporal association between weather and Covid-19 explored by machine learning

Abouzar Ramezani,Somayeh Rafati,Ali Asghar Alesheikh 대한공간정보학회 2023 Spatial Information Research Vol.31 No.5

The Covid-19 epidemic led to loss of the lives of many people in the world and had a very negative impact on the mental and physical health of humans. One of the effective ways to preventive strategies regarding is to study the impact of climatic parameters. This research introduces a new spatiotemporal methodology to explore the association between Covid-19 and hourly data of weather. This methodology developed based on machine learning using unsupervised clustering method. Six counties considered for finding association and the cities that have similar climatic temporal changes clustered and compared with cities that have similar number of Covid-19 cases. For this goal, a new model is developed for finding similarities between clusters, which indicates the association between weather and Covid-19. The result shows similarities are about 57% for wind speed, 63% for temperature, 63% for surface pressure, and 42% for elevation. Then result evaluated sing Kendall’s tau_b and Spearman’s rho which shows the proposed methodology has an acceptable result.

A New DG Nanoscale TFET Based on MOSFETs by Using Source Gate Electrode: 2D Simulation and an Analytical Potential Model

Zeinab Ramezani,Ali A. Orouji 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.71 No.4

This paper suggests and investigates a double-gate (DG) MOSFET, which emulates tunnel field effect transistors (M-TFET). We have combined this novel concept into a double-gate MOSFET, which behaves as a tunneling field effect transistor by work function engineering. In the proposed structure, in addition to the main gate, we utilize another gate over the source region with zero applied voltage and a proper work function to convert the source region from N+ to P+. We check the impact obtained by varying the source gate work function and source doping on the device parameters. The simulation results of the M-TFET indicate that it is a suitable case for a switching performance. Also, we present a two-dimensional analytic potential model of the proposed structure by solving the Poisson’s equation in x and y directions and by derivatives from the potential profile; thus, the electric field is achieved. To validate our present model, we use the SILVACO ATLAS device simulator. The analytical results have been compared with it.

Fabrication and Characterization of Fe(III) Metal-organic Frameworks Incorporating Polycaprolactone Nanofibers: Potential Scaffolds for Tissue Engineering

Mohammad Reza Ramezani,Zeinab Ansari-Asl,Elham Hoveizi,Ali Reza Kiasat 한국섬유공학회 2020 Fibers and polymers Vol.21 No.5

Fabrication of nanofibrous scaffolds of biodegradable polymers provides a great premise for several biologicalapplications. In this study, nanofibrous polycaprolactone (PCL) mats incorporating Fe-MOF (PCL/x%Fe-MOF, x=5, 10, 20)were fabricated by electrospinning technique. The Fe-MOFs were separately synthesized by the hydrothermal method andthen were added to PCL solution for preparation of nanofibrous composites. The presence of Fe-MOF in the fibers wasdemonstrated by various methods including FT-IR (Fourier-transform infrared), PXRD (powder X-ray diffraction), EDS(energy dispersive X-ray spectroscopy) mapping, SEM (scanning electron microscope), and TEM (transmission electronmicroscope). In the FT-IR spectra of the nanocomposites, the characteristic bands for the pure PCL and Fe-MOF showed nosignificant change in their positions, suggesting a weak chemical interaction with each other, although they physically mixeduniformly. Nanofibrous structure of the as-prepared nanocomposites was confirmed by SEM and TEM images. The diameterof PCL nanofibers was measured to be 369 nm. Biological investigations indicated that the experimented scaffolds includingPCL/5%Fe-MOF and PCL/10%Fe-MOF nanofibrous scaffolds provided appropriate surface and mechanical properties suchas cellular biocompatibility, high porosity, chemical stability, and optimum fiber diameter for cell adhesion, viability, andproliferation compared with PCL and PCL/20%Fe-MOF nanocomposites. Indeed, our results demonstrated that percent ofFe-MOF in the composites played a significant role in cell attachment and viability. Also, according to the implantationstudies, up to at least 4 weeks, none of the animals showed any inflammatory response. Totally, we can be claimed that themodified electrospun scaffolds have been developed for tissue engineering applications.

Severe acute respiratory syndrome coronavirus 2 and respiratory syncytial virus coinfection in children

Milad Zandi,Saber Soltani,Mona Fani,Samaneh Abbasi,Saeedeh Ebrahimi,Ali Ramezani 질병관리본부 2021 Osong Public Health and Research Persptectives Vol.12 No.5

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has infected many people around the world. Children are considered an important target group for SARS-CoV-2, as well as other viral infections such as respiratory syncytial virus infection. Both SARS-CoV-2 and respiratory syncytial virus can affect the respiratory tract. Coinfection of SARS-CoV-2 and respiratory syncytial virus can pose significant challenges in terms of diagnosis and treatment in children. This review compares the symptoms, diagnostic methods, and treatment of COVID-19 and respiratory syncytial virus infection in children.

Sublayer assisted by hydrophilic and hydrophobic ZnO nanoparticles toward engineered osmosis process

Sina Mansouri,Soodabeh Khalili,Majid Peyravi,Mohsen Jahanshahi,Rezvaneh Ramezani Darabi,Fatemeh Ardeshiri,Ali Shokuhi Rad 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.11

Hydrophilic and hydrophobic polyethersulfone (PES)-zinc oxide (ZnO) sublayers were prepared by loading of ZnO nanoparticles into PES matrix. Both porosity and hydrophilicity of the hydrophilic sublayer were increased upon addition of hydrophilic ZnO, while these were decreased for the hydrophobic sublayer. In addition, the results demonstrated that the hydrophilic membrane exhibited smaller structural parameter (S value or S parameter or S), which is beneficial for improving pure water permeability and decreasing mass transfer resistance. In contrast, a higher S parameter was obtained for the hydrophobic membrane. With a 2M NaCl as DS and DI water as FS, the pure water flux of hydrophilic TFN0.5 membrane was increased from 21.02L/m2 h to 30.06L/m2 h and decreased for hydrophobic TFN0.5 membrane to 14.98L/m2 h, while the salt flux of hydrophilic membrane increased from 10.12g/m2 h to 17.31g/m2 h and decreased for hydrophobic TFN0.5 membrane to 3.12g/m2 h. The increment in pure water permeability can be ascribed to reduction in S parameter, which resulted in reduced internal concentration polarization (ICP). The current study provides a feasible and low cost procedure to decrease the ICP in FO processes.

Laccase Immobilization onto Magnetic β-Cyclodextrin-Modified Chitosan: Improved Enzyme Stability and Efficient Performance for Phenolic Compounds Elimination

Roghayeh Tarasi,Masoumeh Alipour,Lena Gorgannezhad,Somaye Imanparast,Aliakbar Yousefi-Ahmadipour,Ali Ramezani,Mohammad Reza Ganjali,Abbas Shafiee,Mohammad Ali Faramarzi,Mehdi Khoobi 한국고분자학회 2018 Macromolecular Research Vol.26 No.8

Three types of improved Fe3O4 magnetic nanoparticles (MNPs), including poly(amidoisophthalicacid) coated magnetite nanoparticles (Fe@PA), cyclodextrin (CD) anchored Fe@PA (Fe@PA-CD), and chitosan (Cs) coated Fe@PA-CD (Fe@PACD- Cs) were successfully developed and characterized. Laccase immobilization onto MNPs was carried out via physical adsorption. The maximal and minimal loading capacity were obtained for Fe@PA and Fe@PA-CD-Cs, respectively. Fe@PA-CDCs- laccase exhibited around 100% of the maximum activity at pH 4 and maintained 70% of its initial activity within the temperature range of 15-55 °C; and Cs coated nanoparticles were more efficient than non-coated. Fe@PA-CD-Cs-laccase maintained 70% of its initial activity up to 12 d from the first day of storage at 25 °C whereas the free laccase, Fe@PA-laccase, and Fe@PA-CD-laccase kept 10%, 28%, and 33% of initial activity, respectively. Furthermore, bio-removal of phenolic compounds was performed by the free and immobilized enzyme. Fe@PA-CD-Cs-laccase showed maximal removal with 96.4% and 85.5% for phenol and bisphenol A, respectively. It seems that Fe@PA-CD-Cs could be an appropriate support for immobilization of other enzymes in various industrial application especially bioremoval of phenolic compounds.