Microstructure Evolution, Mechanical Properties and Strain Hardening Instability of Low and Medium Carbon Quenching & Partitioning Steels

Ramadan N. Elshaer,Mohamed K. El‑Fawakhry,Ahmed I. Z. Farahat 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.6

The effect of quenching after martensitic finish (QAMf) or quenching & partitioning (Q&P) on microstructure evolution,mechanical properties, and strain hardening instability of low and medium carbon hot rolled steels were investigated. Twoheats of low and medium carbon steels were cast in an induction open furnace. The chemical composition of low carbonsteel is 0.16C–0.27Si–1.47Mn–0.02Al while medium carbon steel is 0.49C–0.30Si–0.91Mn–0.03Al. They were hot-rolledat 1200 °C for 30 min followed by air cooling. The microstructure after hot-rolled gives bands of ferrite and pearlite for0.16 wt% low carbon steel. On the other hand, 0.49 wt% medium carbon steel produces coarse pearlite islands surrounded byferrite phase. To enhance mechanical properties, it was necessary to modify the microstructure of low and medium carbonsteels using QAMfor Q&P processes. The resultant matrix of microstructure after QAMfand Q&P processes containedferrite, bainite, lath martensite, and retained austenite for 0.16 wt% low carbon steel, and polygonal ferrite, lath martensite,and retained austenite for 0.49 wt% medium carbon steel, respectively. In low carbon steel, QAMfprocess increased uniformelongation from 6.6 to 13.5% (105% increase) while ultimate tensile strength (UTS) improved slightly from 645 to 692 MPa(7% increase). However, in medium carbon steel, Q&P reduced uniform elongation from 12.4 to 4.8% (61% decrease) whileincreased UTS from 769 to 1242 MPa (61.5% increase). It is worthy to mention that QAMfprocess exhibited strain hardeninginstability zone (7.8% strain before necking) compared to hot-rolled process (0% strain before necking). On the otherhand, Q&P process highly decreased strain hardening instability zone (0.77% strain before necking) compared to hot-rolledprocess (3.4% strain before necking).

ON FUZZY BITOPOLOGICAL SPACES IN ŠOSTAK'S SENSE (II)

Ramadan, Ahmed Abd El-Kader,Abbas, Salah El-Deen,El-Latif, Ahmed Aref Abd Korean Mathematical Society 2010 대한수학회논문집 Vol.25 No.3

In this paper, we have use a fuzzy bitopological space (X, $\tau_1$, $\tau_2$) to create a family $\tau_{ij}^s$ which is a supra fuzzy topology on X. Also, we introduce and study the concepts of r-($\tau_i$, $\tau_j$)-generalized fuzzy regular closed, r-($\tau_i$, $\tau_j$)-generalized fuzzy strongly semi-closed and r-($\tau_i$, $\tau_j$)-generalized fuzzy regular strongly semi-closed sets in fuzzy bitopological space in the sense of $\check{S}$ostak. Also, these classes of fuzzy subsets are applied for constructing several type of fuzzy closed mapping and some type of fuzzy separation axioms called fuzzy binormal, fuzzy mildly binormal and fuzzy almost pairwise normal.

Selecting Sensitive Parameter Subsets in Dynamical Models With Application to Biomechanical System Identification

Ramadan, Ahmed,Boss, Connor,Choi, Jongeun,Peter Reeves, N.,Cholewicki, Jacek,Popovich, Jr., John M.,Radcliffe, Clark J. ASME International 2018 Journal of biomechanical engineering Vol.140 No.7

ON INTUITIONISTIC FUZZY SUBSPACES

Ramadan, Ahmed Abd El-Kader,El-Latif, Ahmed Aref Abd Korean Mathematical Society 2009 대한수학회논문집 Vol.24 No.3

We introduce a new concept of intuitionistic fuzzy topological subspace, which coincides with the usual concept of intuitionistic fuzzy topological subspace due to Samanta and Mondal [18] in the case that $\mu=X_A$ for A $\subseteq$ X. Also, we introduce and study some concepts such as continuity, separation axioms, compactness and connectedness in this sense.

Assessing the genotoxicity of oral zinc oxide nanoparticle administration in male rats using micronuclei and comet assay

Amal G. Ramadan(Amal G. Ramadan ),Ahmed A. M. Yassein(Ahmed A. M. Yassein ),Eissa A. Eissa(Eissa A. Eissa ),Gamal M. Hassan(Gamal M. Hassan ) 한국축산식품학회 2022 Food and Life Vol.2022 No.3

Zinc oxide nanoparticles (ZnO-NPs) are regularly utilized in the food and fertilizers industries. In our investigation, rats received oral administration of ZnO NPs with a particle size of 30±5 nm once daily at doses of 100, 200, 300, 400, and 600 mg/kg for ten weeks in order to assess the genotoxic effect. Impacts on hematological markers, genotoxic impact, and growth were investigated. The findings showed that ZnO-NPs significantly reduced body weight gain, red blood cell count (RBC), hemoglobin concentration (Hb), hematocrit value (HCT), and platelet count (PLT), while increasing white blood cell (WBC), mean capsular volume (MCV), mean capsular hemoglobin (MCH), and mean capsular hemoglobin concentration (MCHC) in the treated rats. Our results for the comet assay and micronuclei test show a dosage-dependent increase in DNA fragmentation, which was supported by an increase in the percentage of DNA that is tailed, the length and intensity of DNA tails, and the tail moment, especially at the dose of 600 mg/kg. According to the findings, the frequency of micronucleated cells has increased.

A hybrid MC-HS model for 3D analysis of tunnelling under piled structures

Zidan, Ahmed F.,Ramadan, Osman M. Techno-Press 2018 Geomechanics & engineering Vol.14 No.5

In this paper, a comparative study of the effects of soil modelling on the interaction between tunnelling in soft soil and adjacent piled structure is presented. Several three-dimensional finite element analyses are performed to study the deformation of pile caps and piles as well as tunnel internal forces during the construction of an underground tunnel. The soil is modelled by two material models: the simple, yet approximate Mohr Coulomb (MC) yield criterion; and the complex, but reasonable hardening soil (HS) model with hyperbolic relation between stress and strain. For the former model, two different values of the soil stiffness modulus ($E_{50}$ or $E_{ur}$) as well as two profiles of stiffness variation with depth (constant and linearly increasing) were used in attempts to improve its prediction. As these four attempts did not succeed, a hybrid representation in which the hardening soil is used for soil located at the highly-strained zones while the Mohr Coulomb model is utilized elsewhere was investigated. This hybrid representation, which is a compromise between rigorous and simple solutions yielded results that compare well with those of the hardening soil model. The compared results include pile cap movements, pile deformation, and tunnel internal forces. Problem symmetry is utilized and, therefore, one symmetric half of the soil medium, the tunnel boring machine, the face pressure, the final tunnel lining, the pile caps, and the piles are modelled in several construction phases.

Microporous-activated carbons of type I adsorption isotherm derived from sugarcane bagasse impregnated with zinc chloride

El Nemr Ahmed,Aboughaly Rawan M.,El Sikaily Amany,Masoud Mamdouh S.,Ramadan Mohamed S.,Ragab Safaa 한국탄소학회 2022 Carbon Letters Vol.32 No.1

Sugarcane bagasse has been used as a substrate for the development of microporous nano-activated carbons for the treatment and elimination of dissolved materials from aquatic environment. The activated carbon was produced using chemical activation in one-step method with zinc chloride (ZnCl2) as the activating agent at a carbonization temperatures range from 500 to 900 °C. The effects of temperature and time of carbonization on the activated carbon product properties were thoroughly studied. The activated carbons that resulted were characterized using the N2 adsorption/desorption isotherms, Brunauer–Emmett–Teller method (BET), pore property analysis, micropore (MP) surface area, t-plot surface area, TGA, FTIR, SEM, TEM, and EDX analyses. The prepared activated carbon's point of zero charge, Boehm titration process, iodine removal percentage, and methylene blue number were also investigated. The prepared activated carbon's maximum surface area was achieved using a 2/1 impregnation ratio (dried sugarcane bagasse/ZnCl2) at 600 °C temperature of carbonization and 60 min residence time. 1402.2 m2/g, 0.6214 and 1.41 cm3/g, respectively, were the largest surface area, total pore volume, and micropore volume. As the activation temperature increased, the total pore volume increased and the BET study measured a pore diameter of 0.7 nm and a mean pore diameter of 1.77 nm.

Design and Workspace Analysis of a New Endoscopic Parallel Manipulator

Khalil Ibrahim,Ahmed Ramadan,M. Fanni,Yo Kobayashi,A. A. Abo-Ismail,Masakatus G. Fujie 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

This paper describes the development of a dexterous endoscopic parallel manipulator for laparoscopic surgery using rigid mechanism. Based on the concept of virtual chain and screw theory, previous endoscopic parallel manipulators are deeply investigated to put their synthesis in a systematic rigorous procedure that helps in proposing the new 4-DOF endoscopic parallel manipulator. The inverse and forward kinematics solutions are derived analytically and numerically respectively. The known problem of limited bending angles was solved in the proposed manipulator as it can reach ± 90o in any direction. The proposed manipulator consists of four legs; two legs are 2-PUU (each leg consists of one active prismatic joint and two passive hook joints); the other two legs are 2-PUS (each leg consists of one active prismatic join, one passive hook joint and one passive spherical joint). Four linear motors are used to drive the mechanism. The performance is investigated through simulation by ADAMS software. Dexterous workspace is obtained and this validates the advantageous bending capability of the new proposed manipulator compared to previous ones.

Treatment Outcomes of Epithelial Ovarian Cancers Following Maximum Cytoreduction and Adjuvant Paclitaxel-Carboplatin Chemotherapy: Egyptian NCI Experience

Nassar, Hanan Ramadan,Zeeneldin, Ahmed A,Helal, Amany Mohamed,Ismail, Yahia Mahmoud,Elsayed, Abeer Mohamed,Elbassuiony, Mohamed A,Moneer, Manar M Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.16

Background: Epithelial ovarian cancer (EOC) is the commonest malignancy involving the ovaries. Maximum surgical cytoreduction (MCR) followed by adjuvant taxane-platinum chemotherapy are the standard of care treatments. Aims: To study treatment outcomes of EOC patients that were maximally cyto-reduced and received adjuvant paclitaxel-carboplatin (PC) chemotherapy. Materials and Methods: This retrospective cohort study included 174 patients with EOC treated at the Egyptian National Cancer Institute between 2006 and 2010. For inclusion, they should have had undergone MCR with no-gross residual followed by adjuvant PC chemotherapy. MCR was total abdominal hysterectomy/bilateral salpingo-oophorectomy [TAH/BSO] or unilateral salpingo-oophorectomy [USO] plus comprehensive staging. Results: The median age was 50 years. Most patients were married (97.1%), had offspring (92.5%), were postmenopausal (53.4%), presented with abdominal/pelvic pain and swelling (93.7%), had tumors involving both ovaries (45.4%) without extra-ovarian extension i.e. stage I (55.2%) of serous histology (79.9%) and grade II (87.4%). TAH/BSO was performed in 97.7% of cases. A total of 1,014 PC chemotherapy cycles were administered and were generally tolerable with 93.7% completing 6 cycles. Alopecia and numbness were the commonest adverse events. The median follow up period was 42 months. The 2-year rates for disease free survival (DFS) and overall survival (OS) were 70.7% and 94.8%, respectively. The respective 5-year rates were 52.6% and 81.3%. Advanced stage and high-grade were significantly associated with poor DFS and OS (p<0.001). Age >65 years was associated with poor OS (p =0.008). Using Cox-regression, stage was independent predictor of poor DFS and OS. Age was an independent predictor of poor OS.

A Control Strategy for Designing an Intelligent Controller for Highly Dynamic/Perturbed Systems

Omar Mehrez,Ahmed Ramadan 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

In this paper a control strategy is proposed to deal with highly dynamic systems. It is based on designing an ANFIS based controller, with minimum number of inputs, by training it from the response of a conventional controller working on the same system. The performance of the resultant fuzzy controller is enhanced by optimizing its PID-like gains using Genetic Algorithms. The proposed control strategy is applied to a double inverted pendulum system, when a payload of significant mass is attached to the second link. This issue is important because of its relevance to some applications like humanoid robots. The added mass increases the system perturbation due to its inertial effect. The purpose of the controller is to balance the links around the equilibrium position, defined as the vertical upward one.