In this paper, pursuing a new advised method called Delta method which is basically similar to variational method, we find the ground and excited states, according to a typical quantum Hamiltonian. Moreover, applying ...In this paper, pursuing a new advised method called Delta method which is basically similar to variational method, we find the ground and excited states, according to a typical quantum Hamiltonian. Moreover, applying this method, the upper bound values for the eigenenergies of the so-called ground and excited states are estimated. We will show that this new method, is as beneficial as the traditional variational method which is common in deriving eigenenergies of some of the quantum Hamiltonians. This method helps physics students to broaden their knowledge about the possible mathematical ways;they can use to obtain eigenenergies of some quantum Hamiltonians. The advantage of Delta method to variational method is in its simplicity and reduction of the calculation procedures.展开更多
Fully nonlinear water wave problems are solved using Eulerian-Lagrangian timestepping methods in conjunction with a desingularized approach to solve the mixed boundary valueproblem that arises at each time step. In th...Fully nonlinear water wave problems are solved using Eulerian-Lagrangian timestepping methods in conjunction with a desingularized approach to solve the mixed boundary valueproblem that arises at each time step. In the desingularized approach, the singularities generatingthe flow field are outside the fluid domain. This allows the singularity distribution to be replacedby isolated Rankine sources with the corresponding reduction in computational complexity andcomputer time. A moving boundary technique is applied to e-liminate the reflection waves fromlimited computational boundaries. Examples of the use of the method in three-dimensions are givenfor the exciting forces acting on a modified wigley hull and Series 60 are presented. The numericalresults show good agreements with those of experiments.展开更多
In this paper, the hydrodynamic characteristics and flow field around rectangular and delta hydrofoils, moving with a constant speed beneath the free surface are numerically studied by means of isoparametric boundary ...In this paper, the hydrodynamic characteristics and flow field around rectangular and delta hydrofoils, moving with a constant speed beneath the free surface are numerically studied by means of isoparametric boundary element method （IBEM）. The quantities （source and dipole strengths） and the geometry of the dements are represented by a linear distribution. Two types of three-dimensional hydrofoils （rectangular and delta） are selected with NACA4412 and symmetric Joukowski sections. Some numerical results of pressure distribution, lift, wave-making drag coefficients and velocity field around the hydrofoils are presented. Also, the wave pattern due to moving hydrofoil is predicted at different operational conditions. Comparisons are made between computational results obtained through this method and those from the experimental measurements and other numerical results which reveal good agreement.展开更多
Background: Family planning has clearly been a major public health success as evidenced by substantial fertility decline and reductions in maternal mortality in countries with high contraceptive prevalence rates. Nige...Background: Family planning has clearly been a major public health success as evidenced by substantial fertility decline and reductions in maternal mortality in countries with high contraceptive prevalence rates. Nigerian governments have continued to expand the scope and improve accessibility and availability of contraceptive commodities to improve uptake, giving the numerous benefits. Objective: To determine the trends in contraceptive usage and the preferred method among clients visiting the family planning clinic of University of Port Harcourt Teaching Hospital (UPTH), Nigeria. Method: It was a cross sectional study of all clients who accepted contraceptive methods at the UPTH, between 1st January 2000 and 31st December, 2015. Results: During the period, a total of 9190 clients accepted contraceptive methods, and 40,334 women were delivered in the maternity unit giving an acceptance rate of 1 in 4 deliveries or 22.8%. The acceptors of modern contraceptives increased steadily from 491 clients in 2001 to a peak in 2008 with 1477 clients and sharply declined to 381 in 2009 before increasing gradually again to 519 clients in 2015. The most commonly used method was the male condom by 3194 clients (37.9%), followed by injectables, which was accepted by 2185 clients (23.8%) while 1752 clients (19.1%) used the IUD. Implant contraceptive was used by 915 clients (9.9%), followed by oral contraceptive pills used by 547 (6.0%). Female sterilization was the least commonly used method by 302 clients (3.3%). There was no vasectomy over the 15 years period. Conclusion: Contraceptive trend in Port Harcourt has an ambivalent acceptance pattern. Although male condom and injectable contraceptives are the most commonly used method over time, the subdermal implants are increasingly becoming very popular in recent time. Female sterilization remains the least common method with no record of vasectomy.展开更多
Background: The signal-to-noise ratio (SNR) is recognized as an index of measurements reproducibility. We derive the maximum likelihood estimators of SNR and discuss confidence interval construction on the difference ...Background: The signal-to-noise ratio (SNR) is recognized as an index of measurements reproducibility. We derive the maximum likelihood estimators of SNR and discuss confidence interval construction on the difference between two correlated SNRs when the readings are from bivariate normal and bivariate lognormal distribution. We use the Pearsons system of curves to approximate the difference between the two estimates and use the bootstrap methods to validate the approximate distributions of the statistic of interest. Methods: The paper uses the delta method to find the first four central moments, and hence the skewness and kurtosis which are important in the determination of the parameters of the Pearsons distribution. Results: The approach is illustrated in two examples;one from veterinary microbiology and food safety data and the other on data from clinical medicine. We derived the four central moments of the target statistics, together with the bootstrap method to evaluate the parameters of Pearsons distribution. The fitted Pearsons curves of Types I and II were recommended based on the available data. The R-codes are also provided to be readily used by the readers.展开更多
文摘In this paper, pursuing a new advised method called Delta method which is basically similar to variational method, we find the ground and excited states, according to a typical quantum Hamiltonian. Moreover, applying this method, the upper bound values for the eigenenergies of the so-called ground and excited states are estimated. We will show that this new method, is as beneficial as the traditional variational method which is common in deriving eigenenergies of some of the quantum Hamiltonians. This method helps physics students to broaden their knowledge about the possible mathematical ways;they can use to obtain eigenenergies of some quantum Hamiltonians. The advantage of Delta method to variational method is in its simplicity and reduction of the calculation procedures.
文摘Fully nonlinear water wave problems are solved using Eulerian-Lagrangian timestepping methods in conjunction with a desingularized approach to solve the mixed boundary valueproblem that arises at each time step. In the desingularized approach, the singularities generatingthe flow field are outside the fluid domain. This allows the singularity distribution to be replacedby isolated Rankine sources with the corresponding reduction in computational complexity andcomputer time. A moving boundary technique is applied to e-liminate the reflection waves fromlimited computational boundaries. Examples of the use of the method in three-dimensions are givenfor the exciting forces acting on a modified wigley hull and Series 60 are presented. The numericalresults show good agreements with those of experiments.
文摘In this paper, the hydrodynamic characteristics and flow field around rectangular and delta hydrofoils, moving with a constant speed beneath the free surface are numerically studied by means of isoparametric boundary element method （IBEM）. The quantities （source and dipole strengths） and the geometry of the dements are represented by a linear distribution. Two types of three-dimensional hydrofoils （rectangular and delta） are selected with NACA4412 and symmetric Joukowski sections. Some numerical results of pressure distribution, lift, wave-making drag coefficients and velocity field around the hydrofoils are presented. Also, the wave pattern due to moving hydrofoil is predicted at different operational conditions. Comparisons are made between computational results obtained through this method and those from the experimental measurements and other numerical results which reveal good agreement.
文摘Background: Family planning has clearly been a major public health success as evidenced by substantial fertility decline and reductions in maternal mortality in countries with high contraceptive prevalence rates. Nigerian governments have continued to expand the scope and improve accessibility and availability of contraceptive commodities to improve uptake, giving the numerous benefits. Objective: To determine the trends in contraceptive usage and the preferred method among clients visiting the family planning clinic of University of Port Harcourt Teaching Hospital (UPTH), Nigeria. Method: It was a cross sectional study of all clients who accepted contraceptive methods at the UPTH, between 1st January 2000 and 31st December, 2015. Results: During the period, a total of 9190 clients accepted contraceptive methods, and 40,334 women were delivered in the maternity unit giving an acceptance rate of 1 in 4 deliveries or 22.8%. The acceptors of modern contraceptives increased steadily from 491 clients in 2001 to a peak in 2008 with 1477 clients and sharply declined to 381 in 2009 before increasing gradually again to 519 clients in 2015. The most commonly used method was the male condom by 3194 clients (37.9%), followed by injectables, which was accepted by 2185 clients (23.8%) while 1752 clients (19.1%) used the IUD. Implant contraceptive was used by 915 clients (9.9%), followed by oral contraceptive pills used by 547 (6.0%). Female sterilization was the least commonly used method by 302 clients (3.3%). There was no vasectomy over the 15 years period. Conclusion: Contraceptive trend in Port Harcourt has an ambivalent acceptance pattern. Although male condom and injectable contraceptives are the most commonly used method over time, the subdermal implants are increasingly becoming very popular in recent time. Female sterilization remains the least common method with no record of vasectomy.
文摘Background: The signal-to-noise ratio (SNR) is recognized as an index of measurements reproducibility. We derive the maximum likelihood estimators of SNR and discuss confidence interval construction on the difference between two correlated SNRs when the readings are from bivariate normal and bivariate lognormal distribution. We use the Pearsons system of curves to approximate the difference between the two estimates and use the bootstrap methods to validate the approximate distributions of the statistic of interest. Methods: The paper uses the delta method to find the first four central moments, and hence the skewness and kurtosis which are important in the determination of the parameters of the Pearsons distribution. Results: The approach is illustrated in two examples;one from veterinary microbiology and food safety data and the other on data from clinical medicine. We derived the four central moments of the target statistics, together with the bootstrap method to evaluate the parameters of Pearsons distribution. The fitted Pearsons curves of Types I and II were recommended based on the available data. The R-codes are also provided to be readily used by the readers.
