Nonlinear response of stiffened triceratops under impact and non-impact waves

Chandrasekaran, Srinivasan,Nassery, Jamshed Techno-Press 2017 Ocean systems engineering Vol.7 No.3

Dynamic response analysis of offshore triceratops with stiffened buoyant legs under impact and non-impact waves is presented. Triceratops is relatively new-generation complaint platform being explored in the recent past for its suitability in ultra-deep waters. Buoyant legs support the deck through ball joints, which partially isolate the deck by not transferring rotation from legs to the deck. Buoyant legs are interconnected using equally spaced stiffeners, inducing more integral action in dispersing the encountered wave loads. Two typical nonlinear waves under very high sea state are used to simulate impact and non-impact waves. Parameters of JONSWAP spectrum are chosen to produce waves with high vertical and horizontal asymmetries. Impact waves are simulated by steep, front asymmetric waves while non-impact waves are simulated using Stokes nonlinear irregular waves. Based on the numerical analyses presented, it is seen that the platform experiences both steady state (springing) and transient response (ringing) of high amplitudes. Response of the deck shows significant reduction in rotational degrees-of-freedom due to isolation offered by ball joints. Weak-asymmetric waves, resulting in non-impact waves cause steady state response. Beat phenomenon is noticed in almost all degrees-of-freedom but values in sway, roll and yaw are considerably low as angle of incidence is zero degrees. Impact waves cause response in higher frequencies; bursting nature of pitch response is a clear manifestation of the effect of impact waves on buoyant legs. Non-impact waves cause response similar to that of a beating phenomenon in all active degrees-of-freedom, which otherwise would not be present under normal loading. Power spectral density plots show energy content of response for a wide bandwidth of frequencies, indicating an alarming behaviour apart from being highly nonlinear. Heave, being one of the stiff degrees-of-freedom is triggered under non-impact waves, which resulted in tether tension variation under non-impact waves as well. Reduced deck response aids functional requirements of triceratops even under impact and non-impact waves. Stiffened group of buoyant legs enable a monolithic behaviour, enhancing stiffness in vertical plane.

Prosthesis-Related Abscess on In-111 Leukocyte SPECT/CT Imaging

Nasseri, Farbod,Bhargava, Peeyush The Korea Society of Nuclear Medicine 2012 핵의학 분자영상 Vol.46 No.1

Determination of Tungsten Target Parameters for Transmission X-Ray Tube: A Simulation Study Using Geant4

Mohammad M. Nasseri 한국원자력학회 2016 Nuclear Engineering and Technology Vol.48 No.3

Transmission X-ray tubes based on carbon nanotube have attracted significant attentionrecently. In most of these tubes, tungsten is used as the target material. In this article, thewell-known simulator Geant4 was used to obtain some of the tungsten target parameters. The optimal thickness for maximumproduction of usable X-rays when the target is exposedto electron beams of different energies was obtained. The linear variation of optimalthickness of the target for different electron energies was also obtained. The data obtainedin this study can be used to design X-ray tubes. A beryllium window was considered for theX-ray tube. The X-ray energy spectra at the moment of production and after passing throughthe target and window for different electron energies in the 30e110 keV range were alsoobtained. The results obtained show that with a specific thickness, the target material itselfcan act as filter, which enables generation of X-rays with a limited energy.

Comparison of ARIMA and NNAR Models for Forecasting Water Treatment Plant's Influent Characteristics

Afshin Maleki,Simin Nasseri,Mehri Solaimany Aminabad,Mahdi Hadi 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.9

A reliable forecasting model for each Water Treatment Plant (WTP) influent characteristics is useful for controlling the plant's operation. In this paper Auto-Regressive Integrated Moving Average (ARIMA) and Neural Network Auto-Regressive (NNAR) modeling techniques were applied on a WTP's influent water characteristics time series to make some models for short-term period (to seven days ahead) forecasting. The ARIMA and NNAR models both provided acceptable generalization capability with R2s ranged from 0.44 to 0.91 and 0.45 to 0.92, respectively, for chloride and temperature. Although a more prediction performance was observed for NNAR in comparison with ARIMA for all studied series, the forecasting performance of models was further examined using Time Series Cross-Validation (TSCV) and Diebold-Mariano test. The results showed ARIMA is more accurate than NNAR for forecasting the horizon-daily values for CO2, Cl and Ca time-series. Therefore, despite of the good predictive performance of NNAR, ARIMA may still stands as better alternative for forecasting task of aforementioned series. Thus, as a general rule, not only the predictive performance using R2 statistic but also the forecasting performance of a model using TSCV, are need to be examined and compared for selecting an appropriate forecasting model for WTP's influent characteristics.

Plasmon e plasmon interaction effect on effective medium electrical conductivity (an effective agent for photothermal therapy)

A. SalmanOgli,B. Nasseri,M. Yazdani Kohneh shahri,E. Piskin 한국물리학회 2016 Current Applied Physics Vol.16 No.11

This article presents an investigative study of the photothermal effect of various compound nanoparticles (attaching the several small nanoparticles to a large nanoparticle by linkers). Initially, some compound nanoparticles such as Au-Au nanoparticles were fabricated and the effective medium electrical conductivities, found to vary greatly in gradient with variations in temperature, were analyzed using a nanolens e based approach. A nano-lens forms when Au-Au nanoparticles interact with electromagnetic waves. More precisely, the interaction of larger nanoparticles with an incident light generates a high intensity plasmonic field around it, and the dramatic effect of this near-field on small nanoparticles leads to the creation of a nano-lens. The modeled and experimental results obtained in this study showed that the Plasmon-plasmon interaction, which leads to the formation of a nano-lens with Au-Au nanoparticles, strongly influenced the medium electrical conductivity which is a vital key for detection of cancer cells. The gradient of electrical conductivity correlated directly with the amount of localized heat generation by Au-Au nanoparticles, offering means by which the temperature could be inferred. The amount of heat generated depended on both the number of nanoparticles present and the effectiveness with which they interacted, particularly in such a high intensity nano-lens.

The efficacy of GABAergic precursor cells transplantation in alleviating neuropathic pain in animal models: a systematic review and meta-analysis

Shaghayegh Askarian-Amiri,Solmaz Nasseri Maleki,Seyedeh Niloufar Rafiei Alavi,Arian Madani Neishaboori,Amirmohammad Toloui,Mohammed I. M. Gubari,Arash Sarveazad,Mostafa Hosseini,Mahmoud Yousefifard 대한통증학회 2022 The Korean Journal of Pain Vol.35 No.1

Background: Current therapies are quite unsuccessful in the management of neuropathic pain. Therefore, considering the inhibitory characteristics of GABA mediators, the present systematic review and meta-analysis aimed to determine the efficacy of GABAergic neural precursor cells on neuropathic pain management. Methods: Search was conducted on Medline, Embase, Scopus, and Web of Science databases. A search strategy was designed based on the keywords related to GABAergic cells combined with neuropathic pain. The outcomes were allodynia and hyperalgesia. The results were reported as a pooled standardized mean difference (SMD) with a 95% confidence interval (95% CI). Results: Data of 13 studies were analyzed in the present meta-analysis. The results showed that administration of GABAergic cells improved allodynia (SMD = 1.79; 95% CI: 0.87, 271; P < 0.001) and hyperalgesia (SMD = 1.29; 95% CI: 0.26, 2.32; P = 0.019). Moreover, the analyses demonstrated that the efficacy of GABAergic cells in the management of allodynia and hyperalgesia is only observed in rats. Also, only genetically modified cells are effective in improving both of allodynia, and hyperalgesia. Conclusions: A moderate level of pre-clinical evidence showed that transplantation of genetically-modified GABAergic cells is effective in the management of neuropathic pain. However, it seems that the transplantation efficacy of these cells is only statistically significant in improving pain symptoms in rats. Hence, caution should be exercised regarding the generalizability and the translation of the findings from rats and mice studies to large animal studies and clinical trials.

Evaluation of the heart and lung dosimetric parameters in deep inspiration breath hold using 3D Slicer

Azam Eskandari,Shahrokh Nasseri,Hamid Gholamhosseinian,Sare Hosseini,Mohammad Javad Keikhai Farzaneh,Alireza Keramati,Maryam Naji,Atefeh Rostami,Mehdi Momennezhad 대한방사선종양학회 2020 Radiation Oncology Journal Vol.38 No.1

Purpose: The present study was conducted to compare dosimetric parameters for the heart and left lung between free breathing (FB) and deep inspiration breath hold (DIBH) and determine the most important potential factors associated with increasing the lung dose for left-sided breast radiotherapy using image analysis with 3D Slicer software. Materials and Methods: Computed tomography-simulation scans in FB and DIBH were obtained from 17 patients with left-sided breast cancer. After contouring, three-dimensional conformal plans were generated for them. The prescribed dose was 50 Gy to the clinical target volume. In addition to the dosimetric parameters, the irradiated volumes and both displacement magnitudes and vectors for the heart and left lung were assessed using 3D Slicer software. Results: The average of the heart mean dose (Dmean) decreased from 5.97 to 3.83 Gy and V25 from 7.60% to 3.29% using DIBH (p < 0.001). Furthermore, the average of Dmean for the left lung was changed from 8.67 to 8.95 Gy (p = 0.389) and V20 from 14.84% to 15.44% (p = 0.387). Both of the absolute and relative irradiated heart volumes decreased from 42.12 to 15.82 mL and 8.16% to 3.17%, respectively (p < 0.001); however, these parameters for the left lung increased from 124.32 to 223.27 mL (p < 0.001) and 13.33% to 13.99% (p = 0.350). In addition, the average of heart and left lung displacement magnitudes were calculated at 7.32 and 20.91 mm, respectively. Conclusion: The DIBH is an effective technique in the reduction of the heart dose for tangentially treated left sided-breast cancer patients, without a detrimental effect on the left lung.

Decolorization of Direct Blue 71 solutions using tannic acid/polysulfone thin film nanofiltration composite membrane; preparation, optimization and characterization of anti-fouling

Nader Yousefi,Ramin Nabizadeh,Simin Nasseri,Mehdi Khoobi,Shahrokh Nazmara,Amir Hossein Mahvi 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.8

The objective of this research was to use tannic acid (TA) as polyphenol monomer and trimesoyl chloride (TMC) to synthesize the nano-composite membranes and its application for dye removal from water. The combined effects of factors were studied by response surface methodology (RSM). Synthesized membrane was characterized by field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and water contact angle measurement. The results showed that monomer concentrations and post treatment (time and temperature) had a significant effect on the membrane synthesis. The predicted optimum operational conditions were initial direct blue 71 concentration of 30.31mg/L; time of 16.96 min, applied pressure of 1.16 bar. Fouling mechanism was pore sealing (n=1.96). The excellent antifouling properties and resistance ability to organic and chemical reagents of the prepared composite nanofiltration membranes caused to suggest this membrane for water treatment.

EFFECT OF USING CEMENT KILN DUST AS A NANO-MATERIAL ON THE STRENGTH OF CEMENT MORTARS

Wael Alnahhal,Ramzi Taha,Hammad Al-Nasseri,Safna Nishad 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.4

In this experimental study, the effects of using nano-sized Cement Kiln Dust (CKD) as a partial replacement for Ordinary PortlandCement (OPC) on the strength of cement mortars is investigated. The CKD was milled up to 4 hours in a planetary ball mill. Inaddition to the control cement mortar mixture with 0% CKD, a total of 28 concrete mortar mixtures were prepared with four differentreplacement percentages of nano-CKD (5, 10, 15, and 20 %), and seven different milling times (1, 1.5, 2, 2.5, 3, 3.5, and 4 hours). The compressive strengths of all cement mortar mixtures were evaluated after curing periods of 7, 28, and 56 days. In addition, thechemical, physical and microscopical properties of the nano-CKD were evaluated using Scanning Electron Microscope (SEM),Transmission Electron Microscope (TEM) and X-ray diffraction (XRD). The experimental results showed that the partialreplacement of the OPC with the nano-CKD enhanced the compressive strength of the cement mortar by about 15-30% comparedwith normal mortar without CKD. Moreover, the experimental results indicated that no change was observed in the chemicalcomposition of CKD after 4 hours of milling. However, there was a decrease in the Portlandite content in parallel with an increase inthe density and the surface area.

Correlation between Radiologic Sign of Lumbar Lordosis and Functional Status in Patients with Chronic Mechanical Low Back Pain

Alireza Ashraf,Siamak Farahangiz,Bita Pakniat Jahromi,Nazanin Setayeshpour,Mahshid Naseri,Ali Nasseri 대한척추외과학회 2014 Asian Spine Journal Vol.8 No.5

Study Design: A cross-sectional study. Purpose: To describe the correlation between lumbar lordosis angle and functional status of patients with chronic mechanical low back pain (CMLBP). Overview of Literature: There are different and conflicting opinions regarding the relationship between the degree of lumbar lordosis and functional status of patients with low back pain. Nonetheless, the severity of lordosis is still one of the routine physical exams considered in rehabilitation clinics. Methods: The degree of lumbar lordosis of 150 patients with CMLBP was measured by means of Cobb’s method using sagittal standing spinal radiographs. Subjects with probable secondary causes of low back pain (trauma, congenital anomaly, spinal infection, rheumatologic problems and history of spinal surgery) were excluded. Besides recording demographic data, their score of functional disability was estimated using Oswestry Disability Questionnaire, one of the most useful and reliable questionnaires. Comparison between these data was made regarding different age and gender groups. Results: In this study, 119 subjects were female and 31 male, with an age range of 19–85 years. The average degree of lumbar lordosis was 44.69±11.43 and that of Oswestry disability index (ODI) 30.52%. Although we found a significant direct relationship between age and degree of lumbar lordosis (Pearson’s correlation coefficient, p =0.016, r =0.197), while insignificant correlation was seen between the degree of lumbar lordosis and ODI (p =0.129). Conclusions: There was no significant correlation between the degree of lumbar lordosis and the score of functional disability with regards to different age groups and gender.