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Go to Editorial ManagerConstruction projects are complex projects and their organisations are characterised by a high degree of fragmentation since they are distributed in large areas and clearly they involves of many activities, each one being divided into sub-activities and so on. Hear clear and good communication between projects stakeholders leads to the project being more successful in contrast to when the communication is weak. This paper compares two methods of communication used in Iraqi construction projects during the implementation stage, namely the Face to Face (FTF) approach which is characterised as expensive and disruptive and Computer Mediated Communication (CMC) which represents the modern method in the communication field. The results show that the CMC method is more productive and economic than FTF and takes less time when completing an implementation work; in addition, the people are less affected by emotional factors in the construction project in contrast to FTF.
This paper is concerned with performance on the widely used control technique: adaptive control for synchronization between two identical chaotic systems embedded in the Master and Slave. It is assumed that the parameters of slave system are unknown. The required stability condition is derived to ensure the stability of error dynamics. Adaptive control laws are designed using appropriate parameters estimation law. The system parameters are asymptotically synchronized; thus the slave parameters can be identified. As an application, the proposed scheme is applied to secure communication system. The information signal is transmitted and recovered on the basis of identification parameters also the system is tested under the consideration of the noisy channel. Finally, through Numerical simulation results, the proposed scheme was success in the communication application.
The investigation of the indoor electromagnetic propagation has been performed at the unlicensed industrial, scientific, and medical (ISM) band, which has gained increased attention recently due to high data rate communication systems developed to operate in it. The effect of the incidence angle and materials thicknesses on the reflection coefficients for both horizontal and vertical polarization has been studied. Two-dimensional ray-tracing model has been suggested to simulate the influence of buildings electromagnetic properties on indoor radio channel characteristics, such as signal level, rms delay spread, and coherence bandwidth. Results show that the influence of the permittivity is more important than the influence of the order of reflection considered for the ray- tracing model. It is also shown that, compared with power level, rms delay spread is more sensitive to the building dielectric parameters. Maximum rms delay spread is dependent mainly on the reflectivity of the walls which dependent on the dielectric parameters.
The influence of time delay on the statistical behavior of the first-order phase-locked-loop is investigated in VHF and UHF synchronous communication systems. The Fokker-Plank equation has been proposed to estimate the probability density function (pdf) of phase fluctuations as well as the average time to loss lock in the presence of noise. The result reveal that the degradation in the loop performance occurs under various conditions of detuning when the inherent time delay is present
The dual synchronization of two different pairs of chaotic oscillators: one pair of Duffing oscillators and one pair of Murali-Lakshmanan-Chua (ML-Chua) circuits has been achieved by numerical simulations. The cross-coupling method, where the difference in the voltage between the sum of the two master oscillators' voltages and one of the slave oscillator voltages is injected 10 the other slave oscillator as an electrical current, for the dual synchronization has been used. The accuracy of synchronization of chaos is numerically obtained by calculating the root mean square error (RMSE). A communication scheme is presented, utilizing the chaotic masking (CMS) technique. Encoding and decoding of a message based on dual synchronization of chaos has been demonstrated.
Orthogonal frequency division multiplexing (OFDM) has become a popular modulation method in high-speed wireless communication systems due to its high data rate transmission capability and robustness against multipath fading effects. One of the major drawbacks of OFDM at the transmitter side is the high peak-to-avenge power ratio (PAPR) of the OFJ)M signal. In this paper, an algorithm is proposed to reduce the peak-to-average power ratio of OFDM signal with a large number of sub-carriers. This algorithm is based on the tone reservation method. The computer simulation tests show that the suggested algorithm reduces the PAPR to a factor of S.2S dB and needs less number of iterations as compared with the traditional tone reservation algorithm.
This paper presents a compact, low-cost reconfigurable bandpass filter (BPF) for WiMax, 5G, and WLAN applications. The BPF consists of a half-wavelength resonator folded as C-shaped by a pair of symmetrical PIN diodes and a central quarter-wavelength resonator to form an E- shaped stub-loaded multiple-mode resonator (SL-MMR). The feed line is made of two subsections separated by a gap which acts as a fixed capacitance and allows the filter to have bandpass behavior. The proposed filter is modeled using the even and odd mode analysis to predict the locations of the resonant frequencies. The simulation results show that the filter covers the frequency range (3.38-3.95) GHz with a center frequency of 3.52 GHz at the ON state of a pair of PIN diodes. On the other hand, the BPF covers the frequency range (4.7-5.93) GHz with a center frequency of 5.2 GHz, at the OFF state of the diodes. The results also show a small insertion loss at the filter passband with two sharp transmission zeros at the stopband.
The use of image communication has increased in recent years. In this approach, the encryption process is performed by hiding the processing steps of the wavelet transform. The attacker cannot obtain the original image unless processing steps are known. In this paper, the performance of three different hidden wavelet-based schemes are applied. First, hiding filter types encryption scheme (HFT), second, hiding wavelet packet tree encryption scheme (HWPT), lastly, by combining the previous two methods (HFTWPT). Several experiments are given to illustrate the performance of the proposed schemes.
This experimental research depicts the role of coating hot surfaces by graphite and graphene on the process of heat dissipation from these hot surfaces. Three aluminum specimens have been prepared for test, one of theme is coated by graphite, another one by graphene a while the third is left free of coating for comparison purpose. Each specimen is tested separately in a home-made wind tunnel. A plate electrical heater is adhered on the bottom of the specimen to simulate the generated energy by a heat sink. A heat sink composed of high thermal conductivity was applied between the heater plate and the base plate of heat sink to reduce the contact resistance to heat flow. The experiments are conducted with four turbulent Reynolds number. The results reveal that the sample coated by graphene exhibits the best thermal dissipation while the uncoated specimen shows the worst thermal performance.
The use of image communication has increased in recent years. In this approach, the encryption process is performed by hiding the processing steps of the wavelet transform. The attacker cannot obtain the original image unless processing steps are known. In this paper, the performance of three different hidden wavelet-based schemes are applied. First, hiding filter types encryption scheme (HFT), second, hiding wavelet packet tree encryption scheme (HWPT), lastly, by combining the previous two methods (HFTWPT). Several experiments are given to illustrate the performance of the proposed schemes.
In this paper, a new approach for the positioning (localization) of multi-node systems is presented. Each node including the beacon node contains two types of sensors: one for the distance sensing and the other type is for communication. The main idea of our proposed approach is to use the control of beacon to construct a nodes' tree which is going to be used later by the nodes to know the paths in which the information will flow. During the tree construction the identities of nodes will be known. Every node except the beacon will use the information obtained from its previous neighbor in the tree to find its own location and orientation. Several simulations using visual basic 2012 are implemented to discern the performance of this algorithm.