This work presents the design and performance of a 2.5Gbit/s transimpedance amplifier (TIA) for optical receivers implemented in a 40nm CMOS technology. The TIA is based on an inverting voltage amplifier with a shunt feedback resistor using noise cancelling technique to reduce the input noise. The TIA is followed by two stages of differential limiting amplifiers and the last stage is a 50Ω differential output driver to provide an interface to the measurement setup. The TIA shows a post layout simulated optical sensitivity of −25dBm for a BER= 10−12 and an optical power dynamic range of 25dB. The complete chip achieves a transimpedance gain of 79.5dBΩ, 1.5GHz bandwidth and occupies a chip area of 0.16mm2. The power consumption of the TIA is only 4.5mW and the complete chip dissipates 15mW for a 1.1V single supply voltage.

The presented work describes a plastic optical fiber receiver for gigabit transmission using a resonant cavity light emitting diode (RC-LED). The integrated optical receiver is realized in 0.6μm BiCMOS technology. The main novelty of the presented design is the integration of the equalizer with the optical receiver. A large area Si photodiode is integrated with the optical receiver. The design combines a TIA, equalizer and post amplifier stage followed by a 50 Ω output driver. To minimize power supply noise and substrate noise, a fully differential design is used. A dummy TIA provides a symmetrical input signal reference and a control loop is used to compensate the offset levels. The total transimpedance of the complete receiver chain is in the range of 85dBΩ. The value of the DC gain and the corner frequency of the equalizer can be adapted via an external control voltage to adapt the design to different SI-POF lengths and RC-LED limited bandwidths. The optical receiver operates at a 3.3 V single power supply and the total current consumption is 31mA. The presented optical receiver succeeded to equalize the low-bandwidth transmission system (RC-LED and 50m POF). A data rate of 1Gbit/s can be transmitted over 50m SI-POF with a sensitivity of -13dBm at BER of 10-9

Simplification is an important design step of water supply and irrigation pipes networks. It is recognized by making the original network easier to be understood and analyzed. Water hammer in water-supply networks may give rise to high and low pressures, due to the superposition of reflected pressure waves. The effect of pipes networks’ simplification on water hammer phenomenon is investigated. This study uses a simple two loops pipes network composed of 12 high density polyethylenes (HDPE) pipes with different diameters, thicknesses, and roughness coefficients representing of a general parallel/series system. The network is fed from a boundary head reservoir and loaded by either distributed or concentrated boundary water demands. According to both hydraulic and hydraulic plus water quality equivalence, three levels of simplifications on the original network are performed. Also, the effect of water demands’ concentration on the transient flow is checked. The transient flow in the network is initialized by either concentrated or distributed boundary water demands which are suddenly shut-off or released. Water hammer and mass oscillation (WHAMO) software which uses the implicit finite difference scheme for solving the momentum and continuity equations at unsteady-state case is used in the simulation. All scenarios produced results showed that both hydraulic equivalence and demands’ concentration simplifications increase the transient pressure and flow rate in the simplified network compared with the original one. However, hydraulic plus water quality equivalence simplification results in an adverse effect. It was found that, as the degree of simplification increases the transient pressure head and flow rate of the simplified network deviate more from those of the original network. Therefore, simplifications of the distribution networks should be done with very careful caution.

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Water distribution system (WDS) is an essential component of the entire water supply systems. It represents a vital component of the urban infrastructures that requires significant investment. The basic hydraulic equations describing any WDS are non-linear algebraic equations which must be solved iteratively. Genetic algorithms (GA) are currently one of the state-of-the-art techniques for the optimization of engineering systems including water network design and rehabilitation. They are capable of finding near optimal cost solutions to these problems given certain cost and hydraulic parameters. In this study, an anonymous WDS in Egypt has been selected and designed/rehabilitated using GA under deterministic conditions as single objective and as multi-objective problem. The obtained solutions were compared to the results obtained from the ordinary design using non-optimal methods. Results indicated that GA capable of obtaining a robust WDS with least cost. Multiobjective solution that includes robustness or water quality objective as the 3rd objective could be obtained giving the trade-off curves of the WDS.

Water quality in distribution systems has become a prominent issue in the study of water networks. This study concentrates on chlorine disinfection as an indicator of water quality. The model discussed in this work is based on laboratory and field collected data. The model is applied on a real network which exists in Almonsha city in Upper Egypt. The experimental set-up and procedure of measuring bulk (Kb) and wall (Kw) chlorine decay coefficients are described. The collected field data together with experimental results are used for calibrating the model using extended period simulation. The aim of this study is to find a solution for the absent of the free residual chlorine in several sections of Almonsha water distribution network. The diurnal variations of domestic water consumption are taken into consideration. Also, different values have been assigned for the daily water consumption for both rural and urban zones of the network. Different water resources (surface and underground water) have been involved in the model. Underground water reservoirs and high elevated tanks are included in the simulation. The water level in the high elevated tanks and water table in the feeding wells are studied. The free residual chlorine concentrations (FRCCs) were measured at different sections of the network and used for the model calibration. FRCCs have been simulated in different locations of the network at several times using extended period simulation The results of the field and experimental works have shown that, the initial chlorine concentration (C0) has an effect on Kb, an equation is derived to express the relation between them. Also, another equation is derived for the relation between C0 and Kw. The simulation process was extended for several months to dispose the effect of the initial conditions. It is found that, with the existing system of chlorine injection, some parts of the network keep nil values of FRCC even with an injected free residual chlorine dose reaching to 5 mg/L at the feeding point. A new technique is proposed. This technique is based on superposition method for chlorine disinfection. Finally, with the superposition method, it is found that, the minimum injected chlorine dose which should be injected at the feeding points ranges between 0.83 mg/L to 2 mg/L. This dose is found to be sufficient to keep the minimum FRCC with values not less than 0.3 mg/L for the whole parts of the concerned network at all day hours