Experimental study and modeling of holographic photonic crystals with defects of the spatial and band-gap structures

Results of experimental studies and modeling of holographic photonic crystals (PCs) with defects of their spatial and band-gap structures and also of studying quasi-crystals are presented. Thicklayer photopolymer materials with a hybrid matrix formed on the basis of the sol-gel technology are used for PC production. A method of obtaining delocalized defects is proposed and implemented. A code is written for computer modeling of the spatial PC structure, which offers a clear idea about the appearance of the synthesized crystal and the expected spectral characteristics.     

Investigating the service characteristics of grade 10Kh9V2MFBR-Sh steel

We present the results obtained from chemical and carbide analyses and a study on determining short-term mechanical properties and critical brittleness temperature, as well as data on the heat strength and heat resistance properties of new Grade 10Kh9V2MFBR-Sh steel, which is an analog of Grade Kh10CrWMoVNb9-2 (P92) steel.     

Voltage transient measurements in a distribution network correlated with data from lightning location system and from sequence of events recorders

Measurement units of high-frequency voltage transients have been specifically developed and installed at three different busses of an Italian medium voltage (MV) feeder, mainly composed by overhead lines and located in a rural region characterized by a high ground flash density (4 flashes/km²/yr). Several of the recorded voltage transients in the period from March 2007 to August 2008 are correlated with specific events detected by the Italian lightning location system (LLS) CESI-SIRF and with sequence of protection operations recorded by the utility's data acquisition system. The paper presents the analysis of these correlated events. Moreover, the paper compares some voltage transient measurements with the computer simulation results obtained by a detailed LIOV-EMTP model of the MV feeder response to indirect lightning strokes. The aim of the paper is to provide elements useful to solve the problem of correlating line faults with lightning events.     

Voltage source inverter

A design optimization tool is developed for a three-phase voltage source inverter (VSI) with diode frontend rectifier. The insulated gate bipolar transistor (IGBT)-based pulsewidth modulation (PWM) voltage source inverter with diode front-end rectifier has become the converter of choice for three-phase ac-fed general-purpose industrial motor drives. The converter power stage, which mainly consists of the front-end rectifier, the inverter, the dc link capacitor, the harmonic and electromagnetic interference (EMI) filter, and the thermal management system, as shown in Figure 1 with a motor load, is the primary contributor to the overall converter cost and size. Since there are interdependencies and tradeoffs among components or subsystems in the power converter, it is very desirable to have a systematic methodology and tool for achieving a cost-optimized or size-optimized converter design while meeting the system performance requirement. A design tool will also reduce the development cycle and effort.     

Large area pulsed corona discharge in water for disinfection and pollution control

To investigate the efficiency of submerged pulse corona (SPC) discharges in water we built a laboratory scale, parallel-plate reactor that is part of a closed loop water circulation system. A pulsed voltage is applied across the electrodes. One of the electrodes is coated with a porous ceramic layer to create local field enhancements to initiate corona discharges. For energization of the SPC reactor a pulse generator was developed which is based on a capacitor discharge initiated by a semiconductor switch. A pulse transformer, followed by two magnetic pulse compression stages, produces voltage pulses with amplitudes of up to 30 kV at a pulse width of 0.3 μs. Simulation of the circuit behavior leads to good agreement with voltage and current measurements. Details of the pulse generator and first experimental results concerning the efficiency of radical production are presented. Depending on the conductivity of the water to be treated, pulse currents of > 600 A at a voltage of 20 kV to > 30 kV are obtained for electrode sizes of around 50 cm². The efficiency of the radical production is measured in terms of the hydrogen peroxide (H₂O₂) concentration, which is formed by recombination of hydroxyl radicals (OH.) at sufficiently high concentrations downstream of the plasma reactor. At pulse repetition rates of 20 to 100 Hz, H₂O₂ concentrations of several mg/l are produced, at efficiencies in the range of up to ?1 g/kWh.     

Relaxed multiple routing configurations: IP fast reroute for single and correlated failures

Multi-topology routing is an increasingly popular IP network management concept that allows transport of different traffic types over disjoint network paths. The concept is of particular interest for implementation of IP fast reroute (IP FRR). The authors have previously proposed an IP FRR scheme based on multi-topology routing called Multiple Routing Configurations (MRC). MRC supports guaranteed, instantaneous recovery from any single link or node failure in biconnected networks as well as from many combined failures, provided sufficient bandwidth on the surviving links. Furthermore, in MRC different failures result in routing over different network topologies, which gives a good control of the traffic distribution in the networks after a failure