High frequency (HF) communications have an important role in long distances wireless communications. This frequency band is more important than VHF and UHF, as HF frequencies can cut longer distance with a single hopping. It has a low operation cost because it offers over-the-horizon communications without repeaters, therefore it can be used as a backup for satellite communications in emergency conditions. One of the main problems in HF communications is the prediction of the propagation direction and the frequency of optimum transmission (FOT) that must be used at a certain time. This paper introduces a new technique based on Oblique Ionosonde Station (OIS) to overcome this problem with a low cost and an easier way. This technique uses the

The researcher studied transportation problem because it's great importance in the country's economy. This paper which ware studied several ways to find a solution closely to the optimization, has applied these methods to the practical reality by taking one oil derivatives which is benzene product, where the first purpose of this study is, how we can reduce the total costs of transportation for product of petrol from warehouses in the province of Baghdad, to some stations in the Karsh district and Rusafa in the same province. Secondly, how can we address the Domandes of each station by required quantity which is depending on absorptive capacity of the warehouses (quantities supply), And through r

in this paper sufficient conditions of oscillation of all of nonlinear second order neutral differential eqiation and sifficient conditions for nonoscillatory soloitions to onverage to zero are obtained

Absorption, fluorescence, quantum yield and lifetime of rhodamine 6G in chloroform, methanol and dimethyl sulfoxide were measured. From a comparison of these quantities, with those for solid solutions (solid solutions are obtained by mixing constant volume proportions of dye at a concentration of 1*10-4M/l with different volume proportions from the concentrated solution of polymer in chloroform and dimethyl sulfoxide). The results showed that the addition of polymer to liquid concentrated solutions (1*10-4M/l )of rhodamine 6G dye from expecting [which leading to development active medium for laser dye at high concentration] increase the spectra shift toward high energies, and the luminescence quantum yield but decreasing radiative lifetim

SUMMARY. – Absorption, flourescence, quantum yield and lifetime of rhodamine B in chloroform, methanol and dimethyl sulfoxide were measured. A comparison was done of these quantities with those for solid solutions, which are obtained by mixing constant volume proportions of dye at a concentration of 1×10–4M/l with different volume proportions from the concentrated solution of polymer in chloroform and dimethyl sulfoxide. The results showed that the addition of polymer to liquid concentrated solutions (1×10–4M/l) of rhodamine B dye from expecting, which leads to development of active medium for laser dye at high concentration, increase the spectra shift toward high energies, and the luminescence quantum yield but decreasing radiative

    In this paper, we introduce new conditions to prove that the existence and boundedness of the solution by convergent sequences and convergent series. The theorem of Krasnoselskii, Lebesgue’s dominated convergence theorem and fixed point theorem are used to get some sufficient conditions for the existence of solutions. Furthermore, we get sufficient conditions to guarantee the oscillatory property for all solutions in this class of equations. An illustrative example is included as an application to the main results.

The current study included testing the ability of plant Hydrilla verticillata (L. F.) on the accumulation of two heavy metals in its tissues, and use the plant in phytoremediation. The plant was exposure to different concentrations of chromium and copper metals (2.5, 5, 10, 15, 20) ppm, for a period of fourteen days, for each solution.The results showed that Hydrilla was more efficient in the removal of chromium, where the amount of the remaining concentration of chromium at the last day of the experiment was (0.20 ± 0.014- 0.66 ± 0.114- 0.99 ± 0.176- 0.79 ± 0.073- 1.80 ± 0.131) ppm, while for copper was (0.33 ± 0.06- 1.13 ± 0.39- 1.66 ± 0.05- 1.96 ± 0.043- 2.33 ± 0.0497) ppm at the last day of the experiment, respectively.

The present work aims to study forward osmosis process using different kinds of draw solutions and membranes. Three types of draw solutions (sodium chloride, sodium formate, and sodium acetate) were used in forward osmosis process to evaluate their effectiveness with respect to water flux and reverse salt flux. Experiments conducted in a laboratory-scale forward osmosis (FO) unit in cross flow flat sheet membrane cell.  Three types of membranes (Thin film composite (TFC), Cellulose acetate (CA), and Cellulose triacetate (CTA)) were used to determine the water flux under osmotic pressure as a driving force. The effect of temperature, draw solution concentration, feed and draw solution flow rate, and membrane types, were studied with

The study aims to provide a Suggested model for the application of Virtual Private Network is a tool that used to protect the transmitted data through the Web-based information system, and the research included using case study methodology in order to collect the data about the research area ( Al-Rasheed Bank) by using Visio to design and draw the diagrams of the suggested models and adopting the data that have been collected by the interviews with the bank's employees, and the research used the modulation of data in order to find solutions for the research's problem.

The importance of the study Lies in dealing with one of the vital topics at the moment, namely, how to make the information transmitted via