ERROR probability, BALLISTIC missiles, INERTIAL navigation systems, MONTE Carlo method, and FLIGHT simulators
A circular error probability (CEP) metric in ballistic missile science is an experimental indicator of the accuracy of a missile system. There are a lot of error sources that cause a ballistic missile to deviate from its ideal trajectory, and that causes a deviation from required CEP. This work discusses the problems of dispersion of ballistic missiles due to inertial navigation system (INS) errors. INS deterministic errors are usually calibrated and compensated using some proper techniques. However, INS stochastic errors can be modeled and analyzed. In this study, a chosen missile is thoroughly analyzed using the six degrees-of-freedom missile flight trajectory simulator. A Monte Carlo simulation is used to generate a large number of flight trajectories to inspect the effect of INS stochastic noise on missile CEP. Moreover, a strategy for selecting an adequate sensor according to mission requirements and its corresponding sensor errors is introduced. [ABSTRACT FROM AUTHOR]
To assess the value of endometrial thickness, volume, and sub-endometrial perfusion in women undergoing IVF. In 82 women candidate for ICSI, endometrial thickness and sub-endometrial perfusion were measured with a trans-vaginal 2 D ultrasound and 3 D power Doppler respectively on day of hCG trigger and Embryo transfer (ET). The primary outcome was the clinical pregnancy rate. Endometrial volume showing a statistically significant difference between pregnant and nonpregnant women (4.11 ± 1.19 vs. 3.4 ± 1.1 p =.019) on day of triggering and at ET (4.02 ± 1.15 vs. 3.45 ± 0.90, p =.022). VFI was significantly higher in pregnant group at both days of triggering and ET (0.54 ± 0.48 vs. 0.33 ± 0.31 and 0.47 ± 0.22 vs. 0.34 ± 0.2, p =.02). At cutoff values of 3.265 and 2.95 cm3 (70 & 80% sensitivity, specificity 64.5 & 51.6%, a positive predictive value 38.9 & 34.8%, and negative predictive value 87.0 & 88.9%) to predict pregnancy on the day of hCG trigger & ET respectively. Cutoff value for Endometrial VFI on the day of ET was 0.674 (sensitivity of 70%, specificity of 80.6%, PPV 53.8%, and NPV 89.3%). Higher endometrial volume and VFI were associated with pregnancy. [ABSTRACT FROM AUTHOR]
Kapeel, Ebrahim H., Safwat, Ehab, Kamel, Ahmed M., Khalil, Mohamed K., Elhalwagy, Yehia Z., and Hendy, Hossam
Unmanned Systems. Oct2022, p1-24. 24p.
The flight dynamics of small Unmanned Aerial Vehicles (UAVs) exhibits substantial nonlinear features which should not be ignored in simulation or analysis. In this work, a complete six degrees of freedom (6DOF) and high-fidelity simulation model of a case study of a small fixed-wing UAV is developed. To accurately estimate the nonlinear UAV’s mathematical model, the mass-inertia properties are investigated through experiments. Moreover, the aerodynamic model characteristics are estimated using a semi-empirical technique to estimate the aerodynamic coefficients and derivatives. The propulsion system’s physical characteristics are estimated and analyzed through experimental measurements. The International Standard Atmosphere (ISA) tables are used to develop the atmospheric model. Furthermore, the actuation model is estimated and validated experimentally through system identification techniques. These estimated sub-model data are integrated to complete the nonlinear flight dynamics model in MATLAB® (Simulink). The UAV trim calculations are graphically derived and then the developed model is tested and verified. The open loop simulation results have proved the superiority of the utilized model techniques to describe the UAV motion. Moreover, it gives very optimistic results to test the flight dynamics of the UAV and design a consistent flight control and guidance system. [ABSTRACT FROM AUTHOR]
Middle East Fertility Society Journal. Dec2015, Vol. 20 Issue 4, p290-294. 5p.
HUMAN artificial insemination, CHORIONIC gonadotropins, INFERTILITY treatment, CASE-control method, ELECTRIC stimulation, FOLLICLE-stimulating hormone, and PREGNANCY
Objective: Intrauterine insemination (IUI) is a simple procedure which has been used to treat unexplained infertility. There is no agreement about the optimum time for IUI. An interval of only a few hours exists in which it can be performed. The aim of this study was to find out whether there is a difference in pregnancy rate if IUI is performed 48 h rather than later than 36 h after Human chorionic gonadotropin (hCG) Injection. Setting: infertility clinic, Kasr Alainy, Cairo University Hospital. Materials and methods: A randomized case-control prospective study in which subjects in Group A will perform IUI 48 h after hCG injection after controlled ovarian stimulation, in comparison with Group B (control) in which the IUI will be performed 36 h after hCG injection. Main outcome measures: Pregnancy rate in group A was 22.6% while group B was 10.6% (p=0.049). The mean Number of mature follicles in group A was 2.6±1 follicles, while that of group B was 2.1±0.9 follicles (p= 0.002). Conclusions: A lot of controversy surrounds the correct timing of IUI. Our study showed a statistically significant increase in pregnancy rate up to 22.6% in patients performing IUI 48 h after hCG trigger, compared to the 10.6% in the patients having the procedure done 12 h earlier. [ABSTRACT FROM AUTHOR]
Arnous, Abduo A., ElSayaad, Ibrahim M., and Kamel, Ahmed M.
Egyptian Journal of Hospital Medicine. Oct2021, Vol. 85, p3119-3124. 6p.
HYDROCELE, SURGICAL complications, ORCHIOPEXY, RESEARCH departments, COMPARATIVE studies, and UNIVERSITY hospitals
Background: The inguinal method is utilized for treating hydrocele in the pediatric populace. While, investigations on scrotal orchiopexy have declared herniation or hydrocele repairing via the same scrotal cut as a portion of an orchiopexy operation, there are a few researches investigating the treatments of separated communication hydrocele via a scrotal incision. Objective: To compare between scrotal and inguinal surgery for repair of communicating hydrocele in kids with assessment of surgical period, intraoperative complications, hospitalization, and postoperative complication. Patients and methods: This work was an interventional research accomplished in Department of Surgery, Al-Azhar University Hospital, New Damietta. 40 cases of ages from 1 year to 18 years were scheduled for communicating hydrocele repair; they were randomized into 2 groups: Group-A (scrotal approach) that included 20-cases and group-B (inguinal approach), which included 20-cases. This study was performed on systematic random sampling from April 2020 until October 2020. Results: A highly significant change was found among studied groups regarding surgical period. In addition, a highly significant change was found between the two groups regarding postoperative hospitalization. There was significant change between both groups as regards overall satisfaction, while there was insignificant difference between groups as regards early post-operative complications. Conclusion: The scrotal method for treating the children communicating hydrocele can be another procedure in qualified centers. The key benefits of this method were cosmesis and reduced surgical period. Nevertheless, the commonest early complication was temporal scrotal edema. This procedure delivers a simple method to the anatomical structure included in scrotal and groin pathologic characteristics with no disruptions of the inguinal duct integrity. [ABSTRACT FROM AUTHOR]
Kamel, Ahmed M., Renaudin, Valerie, Nielsen, John, and Lachapelle, Gérard
International Journal of Navigation & Observation. 2013, p1-17. 17p.
INERTIAL navigation systems, FUZZY logic, GLOBAL Positioning System, GUIDED missiles, BANDWIDTHS, PHASE-locked loops, and RADIO interference
Autonomous Navigation Systems used in missiles and other high dynamic platforms are mostly dependent on the Global Positioning System(GPS). GPS users face limitations in terms of missile high dynamics and signal interference. Receiver's tracking loops bandwidth requirements to avoid these problems are conflicting. The paper presents a novel signal frequency and phase tracking algorithm for very high dynamic conditions, which mitigates the conflicting choice of bandwidths and reduces tracking loop measurement noise. It exploits the flexibility of fuzzy control systems for directly generating the required Numerically Controlled Oscillator (NCO) tuning frequency using phase and frequency discriminators information and is labeled Fuzzy Frequency Phase Lock Loop (FFPLL). Because Fuzzy Systems can be computationally demanding and an InertialNavigation System (INS) is often onboard the vehicle, an assisted INS Doppler version has been designed and is also proposed. Assessment of the new GPS trackingmethod is performed with both simulated and experimental data under jamming conditions. The main enhancements of the proposed system consist in reduced processing time, improved tracking continuity and faster reacquisition time. [ABSTRACT FROM AUTHOR]
Background: Tobacco consumption remains a public health issue and is one of the major causes of death in India. This study presents a validated conceptual model to assess the interaction between education, perceived application of tobacco control measures, type of tobacco and their effects on the intention to quit tobacco. Additionally, the direct and mediating roles of tobacco use -frequency, -duration, and -dependency on the intention to quit is also investigated.Methods: An analytical cross-sectional study was carried out, and data from tobacco users of six randomly selected states in India was collected via face-to-face interviews. Structural equation modeling (SEM) was performed using R v 3.6.3 to test the model fit and to explore the association between tobacco control measures and the intention to quit tobacco.Results: From 1962 tobacco users, 43.7% wanted to quit tobacco immediately. Tambakoo (57.7%) was the most common type of tobacco used and 68.9% said that minors could buy tobacco. Findings from SEM showed that that one standard deviation (SD) increase in the perceived application of tobacco control measures is directly associated with a 0.181 SD increase in the intention to quit tobacco (B = 0.181, P < 0.001), and this effect was partially mediated by frequency of tobacco consumption (B = 0.06, P < 0.05). Also, a better education level was associated with a higher intention to quit tobacco (B = 0.14, P < 0.001).Conclusions: To conclude, the application of tobacco control measures and a better education level may positively affect the intention to quit tobacco. The frequency of tobacco use and the number of influencers play an essential role in deciding to quit. In future, longitudinal studies are recommended to further substantiate the evidence. [ABSTRACT FROM AUTHOR]
Khamis, Ahmed, Naidu, D. Subbaram, and Kamel, Ahmed M.
International Journal of Electronics & Telecommunications. Jun2014, Vol. 60 Issue 2, p165-171. 7p.
RICCATI equation, NONLINEAR theories, ARTIFICIAL satellite tracking, GUIDED missiles, ELECTRIC motors, DIFFERENTIAL equations, and SIMULATION methods & models
The majority of homing guided missiles use gimbaled seekers. The equations describing seeker gimbal system are highly nonlinear. Accurate nonlinear control of the motion of the gimbaled seeker through the attached DC motors is required. In this paper, an online technique for finite-horizon nonlinear tracking problems is presented. The idea of the proposed technique is the change of variables that converts the nonlinear differential Riccati equation to a linear Lyapunov differential equation. The proposed technique is effective for wide range of operating points. Simulation results for a realistic gimbaled system with different engagement scenarios are given to illustrate the effectiveness of the proposed technique. [ABSTRACT FROM AUTHOR]
Khamis, Ahmed, Naidu, D. Subbaram, and Kamel, Ahmed M.
International Journal of Aerospace Engineering. 2014, p1-12. 12p.
RICCATI equation, NONLINEAR systems, STOCHASTIC analysis, COMPUTER simulation, and ALGORITHMS
This paper presents an efficient online technique used for finite-horizon, nonlinear, stochastic, regulator, and tracking problems. This can be accomplished by the integration of the differential SDRE filter algorithm and the finite-horizon state dependent Riccati equation (SDRE) technique. Unlike the previous methods which deal with the linearized system, this technique provides finitehorizon estimation and control of the nonlinear stochastic systems. Further, the proposed technique is effective for a wide range of operating points. Simulation results of a missile guidance system are presented to illustrate the effectiveness of the proposed technique. [ABSTRACT FROM AUTHOR]
Tamazin, Mohamed, Noureldin, Aboelmagd, Korenberg, Michael J., and Kamel, Ahmed M.
Journal of Navigation. Jul2016, Vol. 69 Issue 4, p794-814. 21p.
PHASE-locked loops, GLOBAL Positioning System, OPTICAL correlators, MULTIPATH channels, and ORTHOGONALIZATION
The Delay Locked Loop (DLL) tracking algorithm is one of the most widely used in GPS receivers. It uses different correlators such as the Early-Late Slope (ELS) correlator and High-Resolution Correlator (HRC) to mitigate code phase multipath. These techniques are effective for weak multipath environments but they may not be suitable for challenging multipath environments. The Multipath Estimating Delay Lock Loop (MEDLL) shows better performance than the classical methods. However, MEDLL still has limited capabilities in severe multipath environments. This paper introduces a robust multipath mitigation technique based on fast orthogonal search to obtain better delay estimation for GPS receivers. This research utilised a SPIRENT Global Navigation Satellite Systems (GNSS) simulator to compare the performance of the proposed method with other multipath mitigation techniques. Experimental results demonstrated that the performance of the proposed algorithm was better than the classical and advanced techniques under the multipath scenarios tested. [ABSTRACT FROM AUTHOR]