The problem of the high peak to average ratio (PAPR) in OFDM signals is investigated with a brief presentation of the various methods used to reduce the PAPR with special attention to the clipping method. An alternative approach of clipping is presented, where the clipping is performed right after the IFFT stage unlike the conventional clipping that is performed in the power amplifier stage, which causes undesirable out of signal band spectral growth. In the proposed method, there is clipping of samples not clipping of wave, therefore, the spectral distortion is avoided. Coding is required to correct the errors introduced by the clipping and the overall system is tested for two types of modulations, the QPSK as a constant amplitude modulation and 16QAM as a varying amplitude modulation.
In today's world, most business, regardless of size, believe that access to Internet is imperative if they are going to complete effectively. Yet connecting a private computer (or a network) to the Internet can expose critical or confidential data to malicious attack from anywhere in the world since unprotected connections to the Internet (or any network topology) leaves the user computer vulnerable to hacker attacks and other Internet threats. Therefore, to provide high degree of protection to the network and network's user, Firewall need to be used.
Firewall provides a barrier between the user computer and the Internet (i.e. it prevents unauthor
... Show MoreThis paper proposes feedback linearization control (FBLC) based on function approximation technique (FAT) to regulate the vibrational motion of a smart thin plate considering the effect of axial stretching. The FBLC includes designing a nonlinear control law for the stabilization of the target dynamic system while the closed-loop dynamics are linear with ensured stability. The objective of the FAT is to estimate the cubic nonlinear restoring force vector using the linear parameterization of weighting and orthogonal basis function matrices. Orthogonal Chebyshev polynomials are used as strong approximators for adaptive schemes. The proposed control architecture is applied to a thin plate with a large deflection that stimulates the axial loadi
... Show MoreThe city of Derna has distinctive architectural and architectural features, like other Arab and Islamic cities in the Arab West and North Africa. Its markets and shops have taken many different forms and structural forms within the urban fabric of the central commercial zone. The meeting between the various commercial and handicraft jobs and consumers within a spatial area starting with the old markets of the dark market and the agency of the harvest and vegetable market and the mosque of the old and the square of the mosque and the Red Square and the square Kharazin. It then grew linearly towards commercial hubs that were associated with the city's expansion axes. Old markets represent the architectural and planning heritage associated
... Show MoreThe Ozone Monitoring Instrument (OMI) measures the reflected solar radiation in the ultraviolet and visible part in the spectral range that is between 270 and 500 nm, using two channels with a spectral resolution of about 0.5 nm. Ground-level tropospheric ozone is one of the air pollutants of most concern. In the troposphere, near the Earth's surface, human activities lead to ozone concentrations several times higher than the natural background level. To evaluate the ozone distribution over Iraq, the ozone data from OMI were analyzed using geostatistical techniques. Theoretical spherical models provided the best fit for all monthly experimental variograms. The parameters of these variograms (sill, range and nugget) wer
... Show MoreThis research includes the principles of the democracy، and to which extent it can contribute in establishing these principles. Democracy is not only to hold parliamentary or presidential elections but also the result of these elections wills it lead to the emergence of an integrated regime that can actually expresses the citizen's rights and to which extent those citizens can contribute in that regime and control it. Since 2005، when the first elections took place in Iraq after the US occupation of Iraq 2003، Iraqi people are looking to a rule that represented them and achieve their interests after getting rid of the totalitarian regimes and establishing an institutional regime that work by democratic means in order to achieve the so
... Show MoreMany pharmaceutical molecules have solubility problems that until yet consist a hurdle that restricts their use in the pharmaceutical preparations. Lacidipine (LCDP) is a calcium-channel blocker with low aqueous solubility and bioavailability.
Lipid dosage forms are attractive delivery systems for such hydrophobic drug molecules. Nanoemulsion (NE) is one of the popular methods that has been used to solve the solubility problems of many drugs. LCDP was formulated as a NE utilizing triacetin as an oil phase, tween 80 and tween 60 as a surfactant and ethanol as a co-surfactant. Nine formulas were prepared, and different tests performed to ensure the stability of the NEs, such as thermodyna
... Show MoreThe expansion in water projects implementations in Turkey and Syria becomes of great concern to the workers in the field of water resources management in Iraq. Such expansion with the absence of bi-lateral agreement between the three riparian countries of Tigris and Euphrates Rivers; Turkey, Syria and Iraq, is expected to lead to a substantially reduction of water inflow to the territories of Iraq. Accordingly, this study consists of two parts: first part is aiming to study the changes of the water inflow to the territory of Iraq, at Turkey and Syria borders, from 1953 to 2009; the results indicated that the annual mean inflow in Tigris River was decreased from 677 m3/sec to 526 m3/sec, after operating Turkey reserv
... Show MoreObjective: The purpose of this work was to develop and optimize the emulgel formulation of piroxicam with two types of gelling agent chitosan and xanthan gum. The release profiles of prepared formulas were investigated. In addition, the rheology and stability of the best formula were investigated.Methods: Emulsified piroxicam was prepared to use oleic acid, tween 80 and PG with a ratio (3:10:10). In xanthan based emulgel, the xanthan gum (1% and 1.5%) was spread as powder on emulsified piroxicam with stirring until emulgel was formed. In chitosan-based emgels, Chitosan gel was added to emulsified piroxicam and stirring until the Emulgel was constructed. Chitosan gels were prepared by incorporating different concentration, 2%, 3%, 6%
... Show MoreVanadium dioxide nanofilms are one of the most essential materials in electronic applications like smart windows. Therefore, studying and understanding the optical properties of such films is crucial to modify the parameters that control these properties. To this end, this work focuses on investigating the opacity as a function of the energy directed at the nanofilms with different thicknesses(1–100) nm. Effective mediator theories(EMTs), which are considered as the application of Bruggeman’s formalism and the Looyenga mixing rule, have been used to estimate the dielectric constant of VO2 nanofilms. The results show different opacity behaviors at different wavelength ranges(ultraviolet, visible, and infrared). The results depict that th
... Show MoreFe, Co and Sb nanopowders were fruitfully prepared by electrical wire explosion method in Double distilled and de-ionized water (DDDW) media. The formation of iron, cobalt and antimony (FeCoSb) alloy nanopowder was monitored by X-ray diffraction. The x-ray diffraction pattern indicates that there are iron, cobalt and antimony peaks. Optical properties of this alloy nanoparticles were characterized by UV-Visible absorption spectra. The absorption peak position is shifted to the lower wavelengths when the current increases. That means the mean size of the nanoparticles controlled by changing the magnitude of the current. The surface morphological analysis is carried out by employing Scanning Electron Microscope (SEM). Particles with varies
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