Engineering aspects of radio-wave heating for soil remediation and compatibility with biodegradation

Dielectric heating of soil using radio waves (RW) can be applied to support various remediation techniques, namely biodegradation and soil vapor extraction, under in situ, on site or ex situ conditions. To improve the spatial resolution of energy dissipation, the design of rod electrodes was modified with an air gap around the electrode allowing thermal treatment focused to the desired soil volume. A combination of low- and high-frequency electrical energy was successfully applied to homogeneously heat the capillary fringe, the boundary region of saturated and unsaturated zones. The energetic efficiency of the method was evaluated showing that an efficient transformation of RW energy to heat in the target volume can be achieved. By comparing biodegradation and soil respiration under conventional and electric (low-frequency resistive and dielectric RW) heating, the compatibility of the electric heating methods with bioremediation processes could be proven. Therefore, RW-supported microbial degradation of pollutants is a real option for accelerated soil remediation.     

Study of solar radiation stability of modern polymer materials on a large solar furnace

The testing of modern polymer insulators designed for transmission facilities for light stability under the action of solar radiation is considered. The technique of accelerated testing including irradiation of the samples with ultraviolet radiation using a large solar furnace has been proposed.     

Silicon-organic pigment material hybrids for photovoltaic application

Hybrid materials of silicon and organic dyes have been investigated for possible application as photovoltaic material in thin film solar cells. High conversion efficiency is expected from the combination of the advantages of organic dyes for light absorption and those of silicon for charge carrier separation and transport. Low temperature remote hot wire chemical vapor deposition (HWCVD) was developed for microcrystalline silicon (μc-Si) deposition using SiH₄/H₂ mixtures. As model dyes zinc phthalocyanines have been evaporated from Knudsen type sources. Layers of dye on μc-Si and μc-Si on dye films, and composites of simultaneously and sequentially deposited Si and dye have been prepared and characterized. Raman, absorption, and photoemission spectroscopy prove the stability of the organic molecules against the rough HWCVD-Si process. Transient microwave conductivity (TRMC) indicates good electronic quality of the μc-Si matrix. Energy transfer from dye to Si is indicated indirectly by luminescence and directly by photoconductivity measurements. F_xZnPc pigments with x=0,4,8,16 have been synthesized, purified and adsorbed onto H-terminated Si(1 1 1) for electronic state line up determination by photoelectron spectroscopy. For x=4 and 8 the dye frontier orbitals line up symmetrically versus the Si energy gap offering similar energetic driving forces for electron and hole injection, which is considered optimum for bulk sensitization and indicates a direction to improve the optoelectronic coupling of the organic dyes to silicon.     

Modelling a PEM fuel cell stack with a nonlinear equivalent circuit

A nonlinear circuit model of a polymer electrolyte membrane (PEM) fuel cell stack is presented. The model allows the simulation of both steady-state and dynamic behaviour of the stack on condition that the values of some of its parameters are changed in the two operating conditions. The circuit parameters can be obtained by means of simple experimental tests and calculations. A commercial PEM fuel cell stack is modelled as seen from the power conditioning system side, without requiring parameters necessary for complex mathematical models and not easily obtainable by the majority of users. A procedure of parameter determination is developed and a comparison between the simulated and experimental results for both steady-state and dynamic behaviour of the PEM stack is shown.     

Electrosynthesis and characterization of iron selenide thin films

Iron selenide thin films have been deposited onto stainless steel and fluorine-doped tin oxide (FTO) glass substrates by the electrodeposition process, in potentiostatic mode using ferric chloride (FeCl₃) and selenium dioxide (SeO₂) salts. The deposition mechanism and growth of the films were investigated by cyclic voltammetry and chronoamperometry. The structural, morphological, compositional and optical properties of the deposited films have been studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), EDAX and optical absorption techniques, respectively. XRD studies reveal that the films are polycrystalline with monoclinic crystal structure. The surface morphology study shows that grains are uniformly distributed over the entire surface of the substrate. EDAX study reveals that the iron selenide films are rich in iron. Optical absorption study shows the presence of direct transition with bandgap energy of 1.23 eV.     

Effect of modified ITO substrate on electrochromic properties of polyaniline films

In this work, we report the morphological and electrochromic properties of electrochemically synthesized polyaniline (PANI) thin films on bare and modified indium–tin oxide (ITO) glass substrates. In the last case, the surface of ITO glass was covered by a self-assembled monolayer of N-phenyl-γ-aminopropyl-trimethoxysilane (PAPTS). Atomic force microscopy images and perfilometry show that smoother and thinner PANI films were grown on PAPTS-modified ITO substrates. PANI-based electrochromic devices (ECDs) were assembled by using a viscous polymeric electrolyte (PE) of LiClO₄ and polymethyl methacrylate (PMMA) co-dissolved in a mixture of propylene and ethylene carbonate. The architectural design of the devices was glass/ITO/PANI/PE/ITO/glass. A dual ECD was also prepared by collocating a poly(3-methylthiophene) (P3MT) thin film as a complementary electrochromic element. The effect of the PAPTS-modified ITO substrate is reflected in a higher optical transmittance at bleach state and a little less color change at 550 nm of PANI-based ECDs.     

Total-productivity analysis of a Nigerian petroleum-product marketing company

Productivity in Nigeria is decreasing: this has adversely affected the average standard-of-living of the population and led to economic hardship. HIV/AIDS, hunger, disease and wars have lowered African productivity and the effectivenesses of public utilities have declined, while unemployment and crime are on the increase. A computer program, which considers the combined concept of partial productivity, total productivity measurement and reliability in order to analyse the effectiveness of a firm, society or nation has been developed. Its predictions have been tested with data from a Nigerian petroleum-product marketing company, namely Rock Oil and Gas Ltd., Aba, Abia State: the management of this business is representative of those of many Nigerian firms. The developed software (see Appendix) can help in identifying the causes of productivity problems, which can so adversely affect the performance of any organisation.     

A systems approach for sizing a stand-alone residential PEMFC power system

Polymer electrolyte membrane fuel cells (PEMFCs) show great promise in portable, automotive, and stationary applications. They have reached the test and demonstration phase in automotive and power markets today. This paper is focused on a stand-alone residential PEMFC power system that provides the electricity needs of the house. A novel stochastic sizing methodology is developed that considers both fuel cell system dynamics and residential load dynamics in overall system sizing for the stand-alone residential fuel cell power system. Understanding the nature of demand side is critical in stand-alone system sizing. Thus, experimental measurements have been completed to capture the load side dynamics in detail. No such data is found in the current literature. The Threshold Bootstrap method is used to model the residential load demand and to produce many realistic load profiles. Matlab/Simulink is used to run system simulations to determine system sizes based on parameters defined through a designed experiment. Comparison between the proposed sizing method and a possible worst case scenario sizing is given. The new sizing methodology can be used together with sophisticated demand analysis programs to obtain customized sizing for each user as stand-alone power systems become more viable.     

Towards a common benchmark for long-term process control and monitoring performance evaluation.

The COST/IWA benchmark simulation model has been available for seven years. Its primary purpose has been to create a platform for control strategy benchmarking of biological wastewater treatment processes. The fact that the benchmark has resulted in more than 100 publications, not only in Europe but also worldwide, demonstrates the interest for such a tool in the research community. In this paper, an extension of the benchmark simulation model no. 1 (BSM1) is proposed. It aims at facilitating evaluation of two closely related operational tasks: long-term control strategy performance and process monitoring performance. The motivation for the extension is that these two tasks typically act on longer time scales. The extension proposed here consists of 1) prolonging the evaluation period to one year (including influent files), 2) specifying time varying process parameters and 3) including sensor and actuator failures. The prolonged evaluation period is necessary to obtain a relevant and realistic assessment of the effects of such disturbances. Also, a prolonged evaluation period allows for a number of long-term control actions/handles that cannot be evaluated in a realistic fashion in the one week BSM1 evaluation period. In the paper, models for influent file design, parameter changes and sensor failures, initialization procedure and evaluation criteria are discussed. Important remaining topics, for which consensus is required, are identified. The potential of a long-term benchmark is illustrated with an example of process monitoring algorithm benchmarking.     

Occurrence of the angiotensin-converting enzyme inhibiting tripeptides Val-Pro-Pro and Ile-Pro-Pro in different cheese varieties of Swiss origin

The contents of the 2 antihypertensive peptides Val-Pro-Pro (VPP) and Ile-Pro-Pro (IPP) were determined in 101 samples from 10 different Swiss cheese varieties using HPLC with subsequent triple mass spectrometry. In the category of extra hard and hard cheeses, the Protected Denomination of Origin cheeses Berner Alpkäse and Berner Hobelkäse, L’Etivaz à rebibes, Le Gruyère, Sbrinz, Emmentaler (organic and conventional) and in the category of semihard cheeses, the varieties Tilsiter, Appenzeller fat and full fat, Tête de Moine, and Vacherin fribourgeois were screened in the study. The average concentration of the sum of VPP and IPP in the screened cheese varieties varied to a large extent, and substantial variations were obtained for individual samples within the cheese varieties. The lowest average concentration of the 2 tri-petides was found in L’Etivaz à rebibes (n = 3) at 19.1 mg/kg, whereas Appenzeller fat (n = 4) contained the greatest concentration at 182.2 mg/kg. In individual samples, the total concentration of VPP and IPP varied between 1.6 and 424.5 mg/kg. With the exception of a 10-yr-old cheese, VPP was always present at greater concentrations than IPP. Milk pretreatment, cultures, scalding conditions, and ripening time were identified as the key factors influencing the concentration of these 2 naturally occurring bioactive peptides in cheese. The results of the present study show that various traditional cheese varieties contain, on average, similar concentrations of the 2 antihypertensive peptides to the recently developed fermented milk products with blood pressure-lowering property. This may serve as a basis for the development of a functional cheese with blood pressure-lowering property.