The main objective of this paper is to verify the difference between water - steam properties obtained from Vukalovich tables (1940) and these obtained by IAPWS-IF97 model. Vukalovich tables are used as the main reference at Damascus University – Fac
ulty of Mechanical and Electrical Engineering – to acquire water and steam parameters used for vapor power cycles (Rankine Cycle). The last revised release on IAPWS-IF97 (International Association for the Properties of Water and Steam of the Industrial Formulation 1997) was in 2012. IAPWS members are United States of American, Canada, Argentina, Brazil, Britain, Ireland, Czech Republic, Denmark, France, Germany, Greece, Italy,
Switzerland (associate member) Japan, and Russia.
The problem of gliding discharges on high voltage equipment is faced in practice, coith inclined interface, such as cable terminations, bushings.
Many researches present very important results about the relationship between the applied voltages and
this partial discharge . But studies about the insulation systems that have small cross capacitor or that have air gaps are limited, considering many points, one of them: the discharge procedure looks
like the partial discharge in insulators, with longitudinal interfaces.
Achieving precise relationships for such systems and finding the actual discharge behavior gives high scientific efficiency and important application for design of high voltages devices, especially when high voltages, which are changing with time voltage like alternatring and lightning voltages, are applied.
Keeping the voltage within the required limits is one of the key issues of operating a power system. since the voltage in electrical power system is affected significantly by changes of loads and
equivalent circuit of the power system, there is a ne
ed to regulate the voltage with high control ability. Because of the growing use of FACTS in General and STATCOM among them in power systems to improve voltage stability, and because of the need for software that is not always available, the aim of research is to develop a mathematical model, algorithm and software for load flow analysis at the steady state of power system includes static synchronous compensator STATCOM.
The Jacobian matrix in the Newton –Raphson algorithm, which is the relationship between voltage and power mismatches, is extended with the STATCOM variables to adjust the voltage and control of the reactive power witch is injected or absorbed at the point of common coupling, with high controlability.
A Complete software has been developed that includes comprehensive control facilities and exhibits very strong convergence characteristics. A Sophisticated algorithm has been verified and the effectiveness of the program is tested by its application to a number of standard power systems
including the IEEE 5-bus system, and Syrian transmission network 400 kV.
The main objective of this research is to estimate the potential electrical power that can be extracted from closed and out-of-service oil wells situated in the north-eastern part of Syria. The research shows that using Organic Rankine Cycle (ORC) wi
th Isobutane as working fluid can produce net power output under certain conditions. The geothermal cycle used brine solution to
absorb the ground heat.
The polluted insulators problem is one of the most important cases, that faces the electrical networks especially in Syrian Arab Republic because the sources of pollution expand more and more, On the other side, the electrical power supply is related
to the operation of all commercial and daily sectors.
The environmental pollution on the insulators generally causes general breakdowns in the electrical power supply networks of wide areas, This makes great economical losses in all sectors that are related to electrical network.
In this research, the distinct values of insulators pollutions are defined. We then find the relationship between the mentioned values and flashover voltage of polluted insulators in the laboratory. The results of the tests apply on the natural polluted insulators in the outsides. Finally, comparison measurements are made on naturally polluted insulators, and the appropriated procedures to limit the pollution effects .
A new group of Z n - Al alloys suitable for casting was developed in the late sixties, These alloys are
ZA - 8 , ZA - 12 and ZA – 27, where the numbers represent the approximate percentage of aluminum in the alloy. These alloys compete with cast iro
n and copper alloys and aluminum alloys. ZA – 27 alloy is characterized by the biggest strength and lowest density alloy from the rest of ZA alloys. It has
good physical and mechanical properties (good strength, good cast ability, ease of machining, good wear properties and high corrosion resistance).
This research is aimed to study the effect of heat treatment on mechanical properties as well as to improve the wear properties of ZA-27alloy.
Heat treatment of type T4 was applied on ZA-27 alloy (This treatment was done by heating the alloy
to a temperature equal to 370 oC for a period of 3 or 5 hours and then immersion in water followed by
natural aging for 30 days).
Wear testing has been made by using dry sliding test of pin samples on the disk - ZA – 27 alloy after
casting without any treatment and wear tests were performed on heat treated ZA – 27 alloy samples.
The microstructure of the alloy after casting and after heat treatment was examined and the effect of
the microstructure on the wear behavior was studied.
The hardness and tensile strength of heat treated samples were reduced while elongation was increased
compared with alloy after casting. The rate of decrease of hardness was equal to 34.7 %, which is
consistent with solutionizing period. On the contrary, the increase in the solutionizing period decreases strength and increases elongation. The study shows also that the heat treated samples have achieved a significant improvement on wear properties compared to the samples after casting without heat treatment
The aim of this work is to study the effect of the aging heat treatment on the pitting corrosion resistance of martensitic stainless steel. In this research a number of specimens from martensitic stainless steel were subjected to solution treatment a
t 1050 for one hour followed by water quenching then aging in the temperatures range (400-750) for different holding times (1-16 hrs).
After heat treatment, two types of corrosion tests (accelerated test and immersion test) were conducted. The results obtained in this research showed that the pitting corrosion resistance was
affected by Aging temperature and three critical temperatures were found in corrosion test: the
specimens aged at 475 0C had maximum corrosion rate. This may be due to the presence of stringer δ-
ferrite and precipitation of very fine precipitates which precipitated heterogeneously in the martensitic
matrix, which led to an increase in corrosion rate. The specimens aged at temperatures range (550 – 625) 0C had minimum values of corrosion rate, this is attributed to the high volume fraction of retained austenite. The specimens aged at temperatures above 625 had intermediate corrosion rate.
The type of pits, which resulted from two pitting corrosion tests, was independent form the form of δ-ferrite and carbides which presence in microstructure.
Nowadays, wireless networks are spreading more and more. The majority of installed networks have become wireless due to the simplicity of installation; where they do not need an infrastructure. This does not mean that the role of the wired networks i
s being eliminated. Instead, the wireless networks
are considered as a complementary of the wired networks. With all types of networks from personal and local area networks (PAN and LAN) to wide area networks (WAN) especially the Internet,
research has become oriented to focus on the quality of service (QoS) and the integration among all these networks taking into account the Internet which is considered as the backbone for each network that wants to exchange the information with any other network all over the world. In our research, we take into account the quality of service in the broadband networks such as the WiMax network (Worldwide Interoperability for Microwave Access) with IEEE 802.16e standard which covers cities and supports the mobility. This network can be used to interconnect the rural zones with the center of cities, this kind is called point-to-point, or it can be used to cover the cities and is called point-tomultipoint,
The last one is used to interconnect different wireless networks especially the local one which has infrastructure (Wi-fi: Wireless Fidelity) and networks which have many users and called
hotspots. However, the cells of Wi Max in the cities are called hotzones.
We propose a system model that performs the load balancing process between the base stations of WiMax network. This means, the proposed load balancing algorithm exchanges the terminals between the adjacent base stations in order to make the throughput in each base station equals to the throughput
in the others. This will improve the performance of the overall network and increase the available bandwidth for each terminal; in addition, this will increase the number of terminals which can be
served. On one side, these advantages return to the subscribers, they also return to the operator on the other side, not to mention the good renown that the operator will get from subscribers that will make more subscribers join to this network.
The proposed load balancing system can be centralized; implemented in a centralized server connected
to all base stations or distributed system implemented in each base station. The load balancing algorithm which consists of several steps is placed in a controller that achieves it. The load balancing process and the handover procedure have to be fast enough in order to prevent the adverse effect on
the quality of service especially for the real-time applications users.
Background& Objective: This research is carried out to investigate the Anti-inflammatory activity of the alcoholic extract of flower buds of Crataegus laevigata in experimentally-induced arthritis in rats.
Materials & Methods: the inflammation was i
nduced experimentally by Carrageenan, the standard material that causes non-immune acute inflammation. The size of edema was measured before and after the inducing the inflammation, in control group as well as in group treated by extract and by Diclofenac.
The measurements persist until the 4th hour following the injection of Carrageenan. In another set of experiment, the important biomarker, TNF-α, was calibrated in inflammation-induced groups of rats that received extract or Diclofenac and compared with control.
Results: The extract significantly reduced the size of edema compared with control and this effect was not less than that of Diclofenac, the standard anti-inflammatory drug. Indeed, the extract lowered the values of TNF-α.
Conclusion: The Crataegus laevigata has clear anti-inflammatony effect , but it should be further investigated.
Background: The Arak is a common alcoholic spirit in Syria, where it is produced in licensed enterprises and by some proud farmers that produce it from their grapes. However, this drink is often produced outside the controls of the manufacturing cycl
e in terms of fermentation and distillation, thus exposing the consumers to risk of methanol poisoning, which confirms the need to submit Arak’s production to the control as extremely essential.
Materials and Methods: This study is based on a database built on a series of investigations of alcohol poisoning cases; methanol was detected and rated according to the standard chemical methods, where the results have been analyzed and treated by the statistical analysis method used in pharmaceutical research.
Results: The study showed the amount of variation in the concentration of methanol depending on the difference in the method of preparation fermenting grapes between domestic and industrial way. It also showed the role of repeated distillation to reduce the concentration of this toxic substance Conclusion: The results of the analysis reveal the importance of treating the high concentrations of methanol by the repeated distillation process to reach the allowable value, furthermore the importance of applying the control system to provide the quality of this popular spirit.
