18,093 research outputs found
Liquid jet pumped by rising gas bubbles
A two-phase mathematical model is proposed for calculating the induced turbulent vertical liquid flow. Bubbles provide a large buoyancy force and the associated drag on the liquid moves the liquid upward. The liquid pumped upward consists of the bubble wakes and the liquid brought into the jet region by turbulent entrainment. The expansion of the gas bubbles as they rise through the liquid is taken into account. The continuity and momentum equations are solved numerically for an axisymmetric air jet submerged in water. Water pumping rates are obtained as a function of air flow rate and depth of submergence. Comparisons are made with limited experimental information in the literature
Combined radiation, convection, and conduction for a system with a partially transmitting wall
The net radiation method is developed for systems having both opaque and partially transparent walls. Heat convection is present at the surfaces and heat conduction through the windows is taken into account. Specific equations are derived for a window between two parallel plates, where one plate is at an elevated temperature typical of what would be encountered in an electric furnace, and the other plate is being cooled. A two-band model is used with cutoff wavelengths typical of glass or quartz. Numerical results are obtained for the window temperature and the heat flow through the window. The effect on these quantities of various plate temperatures and emissivities is shown
Inelastic behavior of structural components
A more accurate procedure was developed for the determination of the inelastic behavior of structural components. The actual stress-strain curve for the mathematical of the structure was utilized to generate the force-deformation relationships for the structural elements, rather than using simplified models such as elastic-plastic, bilinear and trilinear approximations. relationships were generated for beam elements with various types of cross sections. In the generational of these curves, stress or load reversals, kinematic hardening and hysteretic behavior were taken into account. Intersections between loading and unloading branches were determined through an iterative process. Using the inelastic properties obtained, the plastic static response of some simple structural systems composed of beam elements was computed. Results were compared with known solutions, indicating a considerable improvement over response predictions obtained by means of simplified approximations used in previous investigations
Identifying the most influential risk factors of frequent infant mortality in Iraq
Nowadays, frequent Infant Mortality for the married women are prevailing in Iraq. It may be also considered as a risky phenomenon in developing countries. It is the loss of an infant after viability. The estimated number is 2.5 million deaths occurring in the first month of life in 2017 alone. On the other hand, the survival rates of newborn infants reflect the quality of pregnancy care provided during work and viability and the infrastructure for the infant care in the different regions and countries of the world. Numerous risk factors are causing this phenomenon. Logistic regression is a statistical technique can be used to express the association between the number of infant mortality and the risk factors cause it. It helps to select the most influential risk factors for this case. The aim of this study is to use logistic regression to examine the association between biological, behavioral and lifestyle risk factors and the number of infant mortality, and to identify the most influential risk factors affected it. A simple random sample is drawn with size of 200 persons that consists of all mothers who visit the primary health care centers in Babylon province in year 2018. Seventeen risk factors are representing biological, behavioral and lifestyle factors of women under the study. The results of fitting binary and ordinal logistic regressions with all seventeen risk factors show that four risk factors show a significance effect on the dependent variable. Consequently, a stepwise logistic regression was fitted, and ordinal logistic regression model has fitted. Nevertheless, there are no much differences between the results of these models with different methods of fitting. All results show that husbands working has two times more likely to exhibit infant mortality than Husbands not working. Increasing age at marriage and woman weight were associated with an increased likelihood of exhibiting infant mortality, but increasing number of hours of women's sleeping was associated with a reduction in the likelihood of exhibiting infant mortality
A Bjorken sum rule for semileptonic decays to ground and excited charmed baryon states
We derive a Bjorken sum rule for semileptonic decays to ground and
low-lying negative-parity excited charmed baryon states, in the heavy quark
limit. We discuss the restriction from this sum rule on form factors and
compare it with some models.Comment: 10 pages, RevTex, no figure, Alberta Thy--26--9
There are no abnormal solutions of the BetheSalpeter equation in the static model
The four-point Green's function of static QED, where a fermion and an
antifermion are located at fixed space positions, is calculated in covariant
gauges. The bound state spectrum does not display any abnormal state
corresponding to excitations of the relative time. The equation that was
established by Mugibayashi in this model and which has abnormal solutions does
not coincide with the BetheSalpeter equation. Gauge transformation from the
Coulomb gauge also confirms the absence of abnormal solutions in the
BetheSalpeter equation.Comment: 11 pages, late
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