Comprehensive investigation of coherent optical OFDM-RoF employing 16QAM external modulation for long-haul optical communication system

Given the growing need for long haul transmission that requires a high rate of data, the orthogonal frequency division multiplexing scheme (OFDM), is regarded as a technique with high potentials for high-capacity optical networks. OFDM transmits over both optical and wireless channels, with the data distributed over a huge amount of the subcarrier, and the data is distributed over a huge number of subcarriers. OFDM achieves RF signal for a long-haul transmitting by utilizing Radio over Fiber (RoF) system, which is known to produce higher orthogonality of the OFDM modulated signal designed for the wireless network. RoF systems comprise of heterogeneous networks designed through the use of wireless and optical links. The aim of this paper is to carry out an investigation of the performance of the external modulation in RoF links, while analyzing the shortcomings caused by the various elements of the optical system. The Mach–Zehnder modulator (MZM) can be applied in external modulation, and exhibits a more robust performance when implemented with the OFDM modulation technique

The Role of Nano Particles Additives on The Wear Properties of Al-Pb alloy

The Al-Pb alloy is one of the important alloys, especially for bearings materials. The main problem of Al-Pb alloy is the difference in melting point and immiscibility between aluminum and lead. In this research mechanical alloying method was used to produce Al- 10%Pb- 4.5%Cu by mixing the constituent in a ball mill under argon atmosphere for two hours at 150 rpm , then it was pressed with different applied loads (44100, 49000, 53900, 58800 and 63700N) and at three sintering temperatures (350, 450 and 550℃). The results show that sintering temperature was  the main factor affecting on the microstructure of alloy. The grain size was reduced with increasing sintering temperature and applied load. The results revealed that the best hardness and compressive strength was obtained with 58800N applied load and 450℃ sintering temperature due to the formation of CuAl2 as well as good distribution of Pb. Alumina in a form of micro and nano particles size resulted in a decline in hardness and wear resistance, while micro Al2O3 improved compressive strength and then decreased at high concentration (2wt. %). The addition of micro and nano SiC resulted in  reduced hardness. Micro SiC improves wear resistance and slightly improved the compressive strength while nano SiC increased to some extent the compression strength and reduced wear resistance. The grains size decreased with the increase of the percentage of Al2O3 and SiC (micro and nano) until 1.5% Al2O3 and 1%SiC addition. X-ray diffraction indicated the formation of new Al-Cu intermetallic compound (Cu9Al4) in the alloy containing Al2O3 or SiC associated with disappears of CuAl2. Keywords: Mechanical alloying, Sintering, SEM, EDS, hardness, compressive strength, Wear.

Performance Investigation of Grid Connected Photovoltaic System Modelling Based on MATLAB Simulation

Photovoltaic (PV) systems are normally modeled by employing accurate equations dealing with a behavior the PV system. This model has Characteristic of PV array cells, which are influenced by both irradiation and temperature variations. Grid-connected PV system is considered as electricity generated solar cell system which is connected to the grid utilities. This paper characterizes an exhibiting and simulating of PV system that executed with MATLAB /Simulink. The impact of solar irradiances as well as ambient temperature performances of PV models is investigated and noted that a lower temperature provides maximum power higher so that the open circuit voltage is larger. Furthermore, if the temperature is low, then a considerably short circuit current is low too

Stabilization of Expansive Soils Using Polypropylene Fiber

Current research main aim is to study the effect of adding polypropylene fiber (PPF) on the behavior of expansive soil to reduce the swelling as percentage (0.5, 1 and 2%) of the weight of dry soil. Expansive soil used in this research was prepared artificially by mixing Ca-based bentonite from geological survey and mining company with sandy soil brought from Karbala city as percentage 80% bentonite to 20% sand of dry weight. Multiple laboratory tests have been carried are (Unconfined Compression Test, One-Dimensional Consolidation Test, Swelling Test, Sieve Analysis and Cycle Swell Shrink Test). A conventional odometer cell was modified to allow the study of swell- shrink cycle test to be carried out under controlled temperatures and surcharge pressure. The results showed that the increase in percentage of (PPF) led to decrease the swelling and to increase the unconfined compression strength. The wetting and drying results of (PPF) showed that with continuous cycles the effect of (PPF) keeps on reducing the swelling and the 2% of (PPF) produces less ratio of swell - shrink, which has obtained higher than 57 % in the improvement factor of swell and shrink

Design and Performance of Adaptive Antenna System in LTE 3GPP Transceivers Based Fourier Signals in ITU Channels

3G LTE is next generation step in mobile communications with the promise of peak download rates of at least 100 Mbit/s and upload rates 50 Mbit/s. The evolved version of Long Term Evolution is LTE-Advanced which is being developed by the Third Generation Partnership Project (3GPP). LTE-Advanced will meet or go beyond the requirements of the International Telecommunication Union (ITU) for the fourth generation (4G) radio communication standard. In this paper, we investigate the performance of Adaptive Antenna System in the LTE 3GPP Transceivers. Adaptive Antenna System (AAS) has been developed to adaptively correct antenna impedance mismatch for the LTE 3GPP Transceivers. (AAS)  has been deployed at the receiver module to reduce the fading effects caused by proposed channels model. (AAS) uses various beamforming techniques to focus the wireless beam between the base station and the subscriber station. In this work, the transmitter (SS) and receiver (BS) are fixed and AAS installed at the receiver is used to direct the main beam towards the desired LOS signal and nulls to the multipath signals. Least Mean Square (LMS) algorithm is used. It has been proved through MATLAB simulations that the performance of the system significantly improves by AAS in  International Telecommunication Union (ITU) channels , where beamforming is implemented in the direction of desired user. The performance of the system more increases by increasing the number of antennas at receiver. Keywords: OFDM, LTE 3GPP, LMS, ITU, AAS

Analysis of a framework implementation of the transceiver performances for integrating optical technologies and wireless LAN based on OFDM-RoF

The greatest advantages of optical fibers are the possibility of extending data rate transmission and propagation distances. Being a multi-carrier technique, the orthogonal frequency division multiplexing (OFDM) can be applicable in hybrid optical-wireless systems design owing to its best spectral efficiency for the interferences of radio frequency (RF) and minor multi-path distortion. An optical OFDM-RoF-based wireless local area network (W-LAN) system has been studied and evaluated in this work. The outline for integrating an optical technology and wireless in a single system was provided with the existence of OFDM-RoF technology and the microstrip patch antenna; these were applied in the Optisystem communication tool. The design of the proposed OFDM-RoF system is aimed at supporting mm-wave services and multi-standard operations. The proposed system can operate on different RF bands using different modulation schemes like 4,16 and 64QAM, that may be associated to OFDM and multidata rates up to 5 Gbps. The results demonstrate the robustness of the integrated optical wireless link in propagating OFDM-RoF-based WLAN signals across optical fibers

Fiber optics based schemes modeling and simulation of QoS for Wi-Fi scenarios using OPNET modeler

Wireless Fidelity (Wi-Fi) network is created on the IEEE 802.11 standard. Connections for local devices in homes and business arenas are provided by Wi-Fi units. With the growing demand as well as penetration of wireless services, the wireless networks users now assume Quality of Service (QoS) besides performances comparable to what is accessible from secure networks. In this paper, OPNET Modeler is used as module and for the simulation of a fiber optic-based Wi-Fi network within a fixed local area network. The aim of this paper is to evaluate their Quality of service (QoS) performances in terms of Wi-Fi voice-packet delay and End-to-End for both Wi-Fi base fiber and Wi-Fi base line. Many scenarios, with same Physical and MAC parameters, have many subnet networks are implementing with fiber optics baseline in addition to Wi-Fi baseline, were created in the network OPNET simulation tool for obtaining the results. The results of simulation reveal that base line demonstrated more delay than base fiber

The Efficiency of the Eichhornia Crassipes (Mart)Solms in the Absorption Contamination Water before Discharge in the Tigris River

Carried out this study in the College of Agriculture and forestry / Mosul University during growing season of the water hyacinth Eichhornia crassipes (Mart)Solms  for 2012 included the experiment two factors , first the quality of the water and second time periods of sampling where the measurement of the proportion of heavy elements from the stream of the valley of the Al-Kraze , which is in the effluent  of AL-kosar , and then the Tigris River .in a week if I took samples of the water before entering the receptacle of cultivated plants is the water hyacinth, and then take samples after the presence of water with the plants for two days . Showed results high efficiency water hyacinth in the absorption of mineral elements including heavy with salts with modification number  the EC of the water course of the valley of the Al-Kraze, where it is absorbed by the water entering into the zone of plant growth through the summer months quantities of salinity, nitrate, phosphate, copper, zinc, lead and cadmium of up to 6,4٪ , 55,9٪ , 38,7٪ , 65,8٪ , 51,3٪ , 51,9٪ , 65,6٪ respectively also reduced the number the pH of the water at a rate of 0,21 . Although there is variation in the rates of salinity and the elements present in the water during the time periods of July to September , it has obsorp the plant higher amounts of the element of copper, lead and cadmium in the month of September, while, obsorp the highest level of salinity, nitrate, phosphorus, and zinc, in the month of July . Keywords: pollution, Eichhornia crassipes (Mart)Solms , period of time, quality of water, waste water, heavy meta