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 international shortwave radio stations and the global beacons as the OIS transmitter and a normal HF receiver as the OIS receiver to verify the direction of propagation and the FOT. In addition, the critical frequency for F2 layer (fof2) was estimated in this paper for Iraq experimentally. The proposed technique was tested practically, and FOT range between Baghdad and other remote stations was estimated successfully using a radio receiver from Kenwood model R 1000 with a long wire antenna as a passive OIS system receiver.
The purpose of this paper is to study the instability of the zero solution of some type of nonlinear delay differential equations of fourth order by using the Lyapunov-Krasovskii functional approach; we obtain some conditions of instability of solution of such equation.
In the spreading of the Internet, mobile smart devices, and interactive websites such as YouTube, the educational video becomes more widespread and deliberative among users. The reasons for its spread are the prevalence of technologies, cheap cost, and easy to use. However, these products often lack to the distinction in video production. By following videos of an educational channel on YouTube, some comments found to discuss the lack of the content presented to motivate the learners, which lead to reduce the viewers of the videos. Therefore, there is an important decision to find general standards for the design and production of educational videos. A list of standards has been drawn up to help those interested in producing educational
... Show MoreMany researchers used different methods in their investigations to enhance the heat transfer coefficient, one of these methods is using porous medium. Heat transfer process inside closed and open cavities filled with a fluid-saturated porous media has a considerable importance in different engineering applications, such as compact heat exchangers, nuclear reactors and solar collectors. So, the present paper comprises a review on natural, forced, and combined convection heat transfer inside a porous cavity with and without driven lid. Most of the researchers on this specific subject studied the effect of many parameters on the heat transfer and fluid field inside a porous cavity, like the angle of inclination, the presenc
... Show MoreThis study aims to studying of Person and organization’s environment fit in a sample of Private bank’s reflection in its basic dimensions (Person-organization fit ,Person-Job fit, Person-group fit and Person- Person-fit )in the Work Outcomes (job satisfaction, the intention to leave the job, Job Engagement, and organizational citizenship behavior ).
The questionnair’e has been used as a basic instrument to gather data , As well as personal interviews with some of the staff of the research sample of private banks which were represented by (5) and included banks (Bank of Assyria for investment, the North Bank for Finance and Investment , Bank of the Tigris
... Show MoreThis research was based on two pillars. The first is a comparison between of research done and the result of a particular variable of research indebendently in the united state, and second, knowledge and determine the effect of managers practices on the contributions of personnel. The manager and staff are considered to be the most important elements in the organization and all of them have a duty towards the others which governed by the relationship rules of procedure of the ministry researched, on the one hand and the interests of the organization and hence employees , whether executives or employees within management formations that the availability of an acceptable level of good pract
... Show MorePolymer electrolytes systems compose of (PEO+KI+I2) and (PEO+RbI+I2) with different concentration, and a fixed amount of ethylene carbonate (EC) and propylene carbonate (PC) over temperatures range 293-343 K prepared by solution cast me
... Show MoreMost cultivars of sorghum have low field emergence as common problem. Three experiments were carried out at Agriculture College, Baghdad University. First experiment was conducted in laboratory according to Complete Randomized Design (CRD) with four replicates. Second and third experiments were conducted at field according to Randomized Complete Block Design (RCBD) during the spring and the fall seasons of 2015, respectively, with four replicates for each one. Same two factors were studied at each experiment. First factor was seed priming by seed soaking for 10 hours in distilled water, solvents of GA3, KCl and thiamine (300, 40 and 30 mg*L-1, respectively) and non-primed seed. Second factor was three cultivars of sorghum (Inqath, Kafier an
... Show MoreBackground: Surgery is one and may be the most effective method to treat obesity. In the last decade, Laparoscopic Sleeve Gastrectomy is perceived to be less invasive, technically simple, less morbid and more popular form of bariatric surgery.
Objectives: This study aims to assess the effect of Laparoscopic Sleeve Gastrectomy on Fasting Blood Glucose Levels and Blood Pressure.
Methods: A prospective controlled study in which 50 obese patients were involved, 36 of patients have hypertension and type 2 diabetes mellitus , 7 patients have type 2 diabetes mellitus only, and 7 patients don’t have hypertension or type 2 diabetes. All patients were submitted to Laparosco
... Show MoreThe effect of using three different interpolation methods (nearest neighbour, linear and non-linear) on a 3D sinogram to restore the missing data due to using angular difference greater than 1° (considered as optimum 3D sinogram) is presented. Two reconstruction methods are adopted in this study, the back-projection method and Fourier slice theorem method, from the results the second reconstruction proven to be a promising reconstruction with the linear interpolation method when the angular difference is less than 20°.