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Zr-doped titania of anatase structure type has been prepared by a combined sol–gel and chemical vapour deposition (CVD) process. The material has been characterized by XRD, TEM and chemical analysis. The photocatalytic performance has been investigated in the oxidative decomposition of the pharmaceutical ibuprofen (IBP) down to low ppm concentrations. The change of the composition of the reaction solution after photocatalytic treatment was followed by UV–Vis spectroscopy and GC/MS. Formation of reaction intermediates was studied by HPLC coupled electrospray ionization time-of-flight mass spectrometry ESI-TOF-MS. The catalytic performance has been studied by varying the catalyst and substrate concentration as well as changing the catalyst-to-substrate ratio. The influence of pH, adsorption and re-use of the catalyst has been tested. The results confirm the high catalytic activity of Zr-doped titania compared to pure titania at low catalyst loading. The material shows the improved textural mesoporosity. However, more reaction intermediates were formed, leading to faster deactivation of the photocatalyst. ESI-TOF-MS measurements point to the formation of a couple of reaction intermediates, which poison the catalyst.

Predictive current control is the use of predictive model for controlling load current tracking reference value, which forecasts future current values based on the selection one of the 27 voltage vectors of T-type NPC inverter. The cost function will minimize tolerance between control and reference current and 2 capacitor voltage values. These distortions depend on system load parameter elements. However, they are not the constant in the real event, which vary with operational conditions causing the distortion in control. In this paper, the new inductance estimation method is applied to predict future inductance values on-line, future current values as well as voltage values of 2 capacitors in order to improve the current quality. The proposed method is introduced and compared with the conventional algorithm to express the advantage of new technique. Simulation results are obtained by PSIM software and experimental results verify the feasibility and effectiveness of the algorithm.

Current views of the mechanism of the catalytic isomerization of α-pinene were discussed. Catalytic systems, modifiers, process conditions, and the effect of process conditions on catalytic activity and on the target-product (camphene, dipentene) selectivities of the process were considered. α-Pinene isomerization was investigated over a Belarussian natural aluminosilicate (Al-Si RB), its derivatives modified with HCl and H3PO4, modified diatomite (Al/Dia), and bentonite (ZSM-5/Ben). The commercial aluminosilicate catalyst AS-36 was used as a reference sample. Al-Si RB was treated with 10% HCl (50–250 ml/g) or 10% H3PO4 (50–100 ml/g) at 50°C for 3 h. α-Pinene was isomerized in a round-bottom flask with a backflow condenser under flowing nitrogen. The rotational speed of the stirrer was 10 rps. The highest catalytic activity and the highest camphene selectivity were observed for Al-Si RB treated with 50 ml/g of HCl. With activated Al-Si RB and As-36, 85% α-pinene conversion at 130°C and a catalyst concentration of 0.5 wt % was attained in 5.5 and 7 h, respectively. The camphene selectivity for Al-Si RB treated with 50 ml/g of HCl was 61%, being ∼20 and ∼10% higher than in the case of AS-36 and Al/Dia, respectively. Al-Si RB retained its catalytic activity for 70 h and could be fully regenerated with acetone.

The preparation of nanoporous materials with enhanced stability using an improved synthesis route using reactive inorganic silica and alumina species is reported. This way improved mesoporous molecular sieves were obtained. The synthesized aluminum substituted mesoporous molecular materials (Al-MMS) contain very large pores of 50–200 A size combined with an improved pore wall thickness. Increased wall thickness and Al substitution lead to an improved chemical stability against alkaline solution. The textural, structural and acid properties are investigated by physico-chemical methods. The catalytic performance acidic materials was tested in the benzoylation reaction; amino functionalized materials were studied in the base catalyzed Michael addition.

Pulse width modulation strategies have been developed for indirect matrix converters (IMCs) in order to improve their performance. In indirect matrix converters, the LC input filter is used to remove input current harmonics and electromagnetic interference problems. Unfortunately, due to the existence of the input filter, the input power factor is diminished, especially during operation at low voltage outputs. In this paper, a new space vector modulation (SVM) is proposed to compensate for the input power factor of the indirect matrix converter. Both computer simulation and experimental studies through hardware implementation were performed to verify the effectiveness of the proposed modulation strategy.

This paper proposes the modified SVPWM control algorithm for the three-phase voltage source inverter, which consists of traditional six switches voltage source inverter and three bidirectional switches for creating the ac decoupling circuit. This topology has the advantages such as the ability to reduce the overall power losses in inverter system and beside that, to decrease the leakage ground current from PV panel (in case of photovoltaic systems) which is based on the principle of decoupling when the zero space vectors occur. For avoiding shoot-through states between six traditional switches and three bidirectional switches, a delay time has been inserted into switching time. The delay time has been controlled more complex to guarantee THD of output voltage, it's called three-step switching algorithm. In oder to demonstrate the feasibility of this algorithm, the operation of the inverter and the modified SVPWM method is simulated by using Matlab/Simulink software and implemented in the experimental prototype by using FPGA Virtex 5 (Xilinx).

A highly active photocatalyst based on Fe doped nano-sized TiO2 was successfully synthesized by chemical vapor deposition (CVD) using FeCl3 as iron source. The CVD was carried out by evaporating FeCl3 at 350 °C in nitrogen flow. The samples were characterized by AAS, XRD, XPS, UV-vis and FTIR. The photocatalytic activity of samples with different Fe contents obtained after different treatment times were tested in the oxidation of i-propanol in liquid phase using visible light. Titania and high Fe loaded TiO2 samples showed very low photo catalytic activity. In contrast, low loaded Fe doped TiO2 sample exhibited high photo catalytic activity. The high catalytic activity of this sample could be related to the presence of lattice defects (Ti-OH groups).

Single-state PWM technique (SS PWM) presents an optimised switching losses PWM scheme to be applied for multilevel inverter for possible reducing number of switchings in a sampling period. Nonlinear control characteristics and harmonic distortion factor can be significantly improved if the number of levels is high. To implement a single-state PWM control with minimised voltage error on condition of unbalance dc sources, a compensating technique is required. The paper will propose a possible solution for implementing the SS PWM with minimised voltage error, using carrier based approach. This again demonstrates the utilisation of carrier based and space vector PWM relationship in solving various optimised PWM problems in multilevel inverters.

Nowadays, an intensive development of multilevel inverters has been seen in hybrid and fuel cell electric vehicles. For this, a high voltage cascade inverter with step pulse PWM strategy is an applicable topology as it can reduce electromagnetic interference as well as switching losses on power devices. The converter is usually controlled with a look-up table of commutation angles, which are computed off-line base on an assumption of equal dc voltage sources. However, in reality, the inequality of these dc voltage sources can occur due to different charging/discharging processes and this reduces the quality of output voltages such as the existence of low order harmonics and an error in fundamental voltage. To overcome this problem, PWM angles in the look-up table can be changed according to different cases of dc source variation. However, this solution may require a large memory for the look-up table. Thus, off-line PWM stratergy in case of dc voltage source variation may not be a suitable approach to control the converter. In this paper, an on-line step pulse PWM method will be proposed to control fundamental voltage and reduce the amplitudes of low-order harmonics to possibly low values. Similar to the original on-line method, the control principle between two defined trajectories will be appropriately modified for solving the problem. The principle is mathematically formulated, and demonstrated by simulation results.

Novel nano-structured materials: nano-particle materials like V-SiO2, TiO2 and nano-sized pore materials like Si-MCM-41, Ti-MCM-41 and Al-MCM-41Analogues were successfully synthesised using different methods: precipitation, sol-gel, micro-emulsion and hydrothermal treatment. These obtained nano-structured materials were characterised by using different physico-chemical methods: FE-SEM, TEM, XRD, IR, UV-vis and nitrogen adsorption/desorption (BET). These materials were examined to investigate adsorptive and catalytic properties of the materials. Nano TiO2 exhibited highly photocatalytic activity in the degradation of methyl red (MR). Pure silica form MCM-41 (Si-MCM-41Analogue) was a selective absorbent for VOCs (m-xylene) removal. Ti substituted MCM-41Analogue exhibited highly photocatalytic activity in the degradation of red phenol (RP) while Al substituted MCM-41Analogue showed high catalytic cracking of petroleum residue (Bach Ho oil field – Vietnam). The obtained results are discussed and rationalised.