Abstract: In this study, photocatalytic degradation of phenol by
titanium dioxide (TiO2) in aqueous solution was evaluated. The UV
energy of solar light was utilized by compound parabolic collectors
(CPCs) technology. The effect of irradiation time, initial pH, and
dosage of TiO2 were investigated. Aromatic intermediates (catechol,
benzoquinone, and hydroquinone) were quantified during the reaction
to study the pathways of the oxidation process. 94.5% degradation
efficiency of phenol was achieved after 150 minutes of irradiation
when the initial concentration was 100 mg/L. The dosage of TiO2
significantly affected the degradation efficiency of phenol. The
observed optimum pH for the reaction was 5.2. Phenol photocatalytic
degradation fitted to the pseudo-first order kinetic according to
Langmuir–Hinshelwood model.
Abstract: A thin gold metal layer was deposited on the top of
silicon oxide films containing embedded Si nanocrystals (Si-nc). The
sample was annealed in a gas containing nitrogen, and subsequently
characterized by photoluminescence. We obtained 3-fold
enhancement of photon emission from the Si-nc embedded in silicon
dioxide covered with a Gold layer as compared with an uncovered
sample. We attribute this enhancement to the increase of the
spontaneous emission rate caused by the coupling of the Si-nc
emitters with the surface plasmons (SP). The evolution of PL
emission with laser irradiated time was also collected from covered
samples, and compared to that from uncovered samples. In an
uncovered sample, the PL intensity decreases with time,
approximately with two decay constants. Although the decrease of
the initial PL intensity associated with the increase of sample
temperature under CW pumping is still observed in samples covered
with a gold layer, this film significantly contributes to reduce the
permanent deterioration of the PL intensity. The resistance to
degradation of light-emitting silicon nanocrystals can be increased by
SP coupling to suppress the permanent deterioration. Controlling the
permanent photodeterioration can allow to perform a reliable optical
gain measurement.
Abstract: Crude oil is a major source of global energy. The major problem is its widespread use and demand resulted is in increasing environmental pollution. One associated pollution problem is ‘oil spills’. Oil spills can be remediated with the use of chemical dispersants, microbial biodegradation and microbial metabolites such as biosurfactants. Four different minimal salt media for biosurfactant production by Bacillus isolated from oil contaminated sites from Oman were screened. These minimal salt media were supplemented with either glucose or sucrose as a carbon source. Among the isolates, W16 and B30 produced the most active biosurfactants. Isolate W16 produced better biosurfactant than the rest, and reduced surface tension (ST) and interfacial tension (IFT) to 25.26mN/m and 2.29mN/m respectively within 48h which are characteristics for removal of oil in contaminated sites. Biosurfactant was produced in bulk and extracted using acid precipitation method. Thin Layer Chromatography (TLC) of acid precipitate biosurfactant revealed two concentrated bands. Further studies of W16 biosurfactant in bioremediation of oil spills are recommended.
Abstract: Antenna arrays are widely used in modern radio systems in sonar and communications. The solving of the detection problems of a useful signal on the background of noise is based on the GLRT method. There is a large number of problem which depends on the known a priori information. In this work, in contrast to the majority of already solved problems, it is used only difference spatial properties of the signal and noise for detection. We are analyzing the influence of the degree of non-coherence of signal and noise unhomogeneity on the performance characteristics of different GLRT statistics. The description of the signal and noise is carried out by means of the spatial covariance matrices C in the cases of different number of known information. The partially coherent signalis is simulated as a plane wave with a random angle of incidence of the wave concerning a normal. Background noise is simulated as random process with uniform distribution function in each element. The results of investigation of degradation of performance characteristics for different cases are represented in this work.
Abstract: Thyristor based firing angle controlled voltage regulators are extensively used for speed control of single phase induction motors. This leads to power saving but the applied voltage and current waveforms become non-sinusoidal. These non-sinusoidal waveforms increase voltage and thermal stresses which result into accelerated insulation aging, thus reducing the motor life. Life models that allow predicting the capability of insulation under such multi-stress situations tend to be very complex and somewhat impractical. This paper presents the fuzzy logic application to investigate the synergic effect of voltage and thermal stresses on intrinsic aging of induction motor insulation. A fuzzy expert system is developed to estimate the life of induction motor insulation under multiple stresses. Three insulation degradation parameters, viz. peak modification factor, wave shape modification factor and thermal loss are experimentally obtained for different firing angles. Fuzzy expert system consists of fuzzyfication of the insulation degradation parameters, algorithms based on inverse power law to estimate the life and defuzzyficaton process to output the life. An electro-thermal life model is developed from the results of fuzzy expert system. This fuzzy logic based electro-thermal life model can be used for life estimation of induction motors operated with non-sinusoidal voltage and current waveforms.
Abstract: The present study is aimed at alteration of sewage sludge into stable compost product using vermicomposting of sewage sludge mixed with cattle manure and saw dust in five different proportions based on C/N ratios (C/N 15 (R1), 20 (R2), 25 (R3) and 30 (R4); and control (R5)) by employing an epigeic earthworm Eisenia fetida. Higher reductions in C/N ratio, CO2 evolution and OUR were observed in R4 demonstrated the compost stability. In addition, R4 proved to be best combination for the growth of the earthworms. In order to observe the optimal degradation, kinetics for degradation of organic matter in vermicomposting were quantitatively evaluated. An approach model was developed by assuming that composting process is carried out in a homogeneous way and the kinetics for decomposition reaction is represented by a Monod-type equation. The results exhibit comparable variations in the kinetic constants Km and K3 under varying parameters during vermicomposting process. Results suggested that higher R2 value in R4, enhanced suitability towards Lineweaver-Burke plot. R4 yields higher degradability coefficient (K) reveals that the occurrence of optimal nutrient balance, which not only enhanced the affinity of enzymes towards substrate but also improved its degradation process. Therefore, it can be proved that R4 provided to be the best feed combination for vermicomposting process as compared to other reactors.
Abstract: In this study sugarcane field soils with a long history of atrazine application in Chachoengsao and Chonburi provinces have been explored for their potential of atrazine biodegradation. For the atrazine degrading bacteria isolation, the soils used in this study named ACS and ACB were inoculated in MS-medium containing atrazine. Six short rod and gram-negative bacterial isolates, which were able to use this herbicide as a sole source of nitrogen, were isolated and named as ACS1, ACB1, ACB3, ACB4, ACB5 and ACB6. From the 16S rDNA nucleotide sequence analysis, the isolated bacteria ACS1 and ACB4 were identified as Rhizobium sp. with 89.1-98.7% nucleotide identity, ACB1 and ACB5 were identified as Stenotrophomonas sp. with 91.0-92.8% nucleotide identity, whereas ACB3 and ACB6 were Klebsiella sp. with 97.4-97.8% nucleotide identity.
Abstract: OFDM systems are known to have a high PAPR (Peak-to-Average Power Ratio) compared with single-carrier systems. In fact, the high PAPR is one of the most detrimental aspects in the OFDM system, as it can cause power degradation (Inband distortion) and spectral spreading (Out-of-band radiation). In this paper, from the foundation of the PAPR analysis an effective method of PAPR reduction has been proposed based on Orthogonal Eigenvector Matrix (OEM) transform. Extensive computer simulations show that a PAPR reduction of up to 4.4 dB can be obtained without introducing in-band distortion or out-of-band radiation in the system.
Abstract: Silicon substrates coated with multiwalled carbon nanotubes (MWCNTs) were experimentally investigated to determine spark breakdown voltages relative to uncoated surfaces, the degree of surface degradation associated with the spark discharge, and techniques to minimize the surface degradation. The results may be applicable to instruments or processes that use MWCNT as a means of increasing local electric field strength and where spark breakdown is a possibility that might affect the devices’ performance or longevity. MWCNTs were shown to reduce the breakdown voltage of a 1mm gap in air by 30-50%. The relative decrease in breakdown voltage was maintained over gap distances of 0.5 to 2mm and gauge pressures of 0 to 4 bar. Degradation of the MWCNT coated surfaces was observed. Several techniques to improve durability were investigated. These included: chromium and gold-palladium coatings, tube annealing, and embedding clusters of MWCNT in a ceramic matrix.
Abstract: This paper presents a novel Global Navigation Satellite System (GNSS) Avionics Based Integrity Augmentation (ABIA) system architecture suitable for civil and military air platforms, including Unmanned Aircraft Systems (UAS). Taking the move from previous research on high-accuracy Differential GNSS (DGNSS) systems design, integration and experimental flight test activities conducted at the Italian Air Force Flight Test Centre (CSV-RSV), our research focused on the development of a novel approach to the problem of GNSS ABIA for mission- and safety-critical air vehicle applications and for multi-sensor avionics architectures based on GNSS. Detailed mathematical models were developed to describe the main causes of GNSS signal outages and degradation in flight, namely: antenna obscuration, multipath, fading due to adverse geometry and Doppler shift. Adopting these models in association with suitable integrity thresholds and guidance algorithms, the ABIA system is able to generate integrity cautions (predictive flags) and warnings (reactive flags), as well as providing steering information to the pilot and electronic commands to the aircraft/UAS flight control systems. These features allow real-time avoidance of safety-critical flight conditions and fast recovery of the required navigation performance in case of GNSS data losses. In other words, this novel ABIA system addresses all three cornerstones of GNSS integrity augmentation in mission- and safety-critical applications: prediction (caution flags), reaction (warning flags) and correction (alternate flight path computation).
Abstract: Water pollution is a major concern for the pulp and paper industry due to the large quantities of effluents generated. Biodegradation of industrial Lignin and AOX by a fungal isolate identified as Aspergillus flavus, white rot fungi which was isolated from Pulp and Paper effluent was studied in batch flask system with industrial effluent and synthetic solution. The flasks were operated at temperature 32°C at 200rpm for eight days in continuous mode. The average overall pH, Temperature, DO, C.O.D, T.D.S, T.S.S, Lignin, AOX were up to 4.56, 32oC, 4.2mg/l, 104mg/l, 6000 mg/l, 4000mg/l, 575.5mg/l, 2195 mg/l respectively after treatment. The Aspergillus flavus sp was the most effective in the biodegradation of Lignin of pulp industry for 94% at 480nm, AOX for 62% at 510nm and of chemical oxygen demand levels for 45% after 8 days of incubation. The optimal conditions found were 4 pH and 32oC temperature for lignin and AOX degradation.
Abstract: Solar cells used in orbit are exposed to radiation environment mainly protons and high energy electrons. These particles degrade the output parameters of the solar cell. The aim of this work is to characterize the effects of electron irradiation fluence on the J (V) characteristic and output parameters of GaAs solar cell by numerical simulation. The results obtained demonstrate that the electron irradiation-induced degradation of performances of the cells concerns mainly the short circuit current
Abstract: The present study shows a method to recover lead metal from wastewater of wet scrubber in secondary lead smelter. The wastewater is loaded with 42,000 ppm of insoluble lead compounds (TSP) submicron in diameter. The technical background benefits the use of cationic polyfloc solution to flocculate these colloidal solids before press filtration. The polymer solution is injected in the wastewater stream in a countercurrent flow design. The study demonstrates the effect of polymer dose, temperature, pH, flow velocity of the wastewater and different filtration media on the filtration extent. Results indicated that filtration rate (¦r), quality of purified water, purifying efficiency (¦e) and floc diameter decrease regularly with increase in mass flow rate and velocity up to turbulence of 0.5 m.sec-1. Laminar flow is in favor of flocculation. Polyfloc concentration of 0.75 – 1.25 g/m3 wastewater is convenient. Increasing temperature of the wastewater and pneumatic pressure of filtration enhances ¦r. High pH value deforms floc formation and assists degradation of the filtration fabric. The overall efficiency of the method amounts to 93.2 %. Lead metal was recovered from the filtrate cake using carbon as a reducing agent at 900°C.
Abstract: In this study, tapioca starch, which acts as natural polymer, was added in the blend in order to produce biodegradable product. Low density polyethylene (LDPE) and tapioca starch blends were prepared by extrusion and the test sample by injection moulding process. Ethylene vinyl acetate (EVA) acts as compatibilizer while glycerol as processing aid was added in the blend. The blends were characterized by using melt flow index (MFI), fourier transform infrared (FTIR) and the effects of water absorption to the sample. As the starch content increased, MFI of the blend was decreased. Tensile testing were conducted shows the tensile strength and elongation at break decreased while the modulus increased as the starch increased. For the biodegradation, soil burial test was conducted and the loss in weight was studied as the starch content increased. Morphology studies were conducted in order to show the distribution between LDPE and starch.
Abstract: This paper interested in the mechanical deformation behavior of shear deformable functionally graded ceramic-metal (FGM) plates. Theoretical formulations are based on power law theory when build up functional graded material. The mechanical properties of the plate are graded in the thickness direction according to a power-law Displacement and stress is obtained using finite element method (FEM). The load is supposed to be a uniform distribution over the plate surface (XY plane) and varied in the thickness direction only. An FGM’s gradation in material properties allows the designer to tailor material response to meet design criteria. An FGM made of ceramic and metal can provide the thermal protection and load carrying capability in one material thus eliminating the problem of thermo-mechanical deformation behavior. This thesis will explore analysis of FGM flat plates and shell panels, and their applications to r structural problems. FGMs are first characterized as flat plates under pressure in order to understand the effect variation of material properties has on structural response. In addition, results are compared to published results in order to show the accuracy of modeling FGMs using ABAQUS software.
Abstract: Homogeneous graft copolymerization of methyl methacrylate (MMA) onto cellulose was carried out in N, N – dimethyl acetamide/LiCl (DMAc/LiCl) and dimethyl sulfoxide/ paraformaldehyde (DMSO/PF) solvent system taking ceric ammonium nitrate (CAN), benzoyl peroxide (BPO) and tin (II)-2-ethyl hexanoate [Sn(Oct)2] as initiators. Different grafting parameters like graft yield (GY), grafting efficiency (GE) and total conversion of monomer to polymer (TC) were evaluated at different reaction conditions of temperature, time, and variation of the amount of monomer and initiator. The viscosity average molecular weight of grafted PMMA and number of grafts per cellulose chain were also calculated. The products were characterized by FT-IR and 1H-NMR analyses and possible reaction mechanisms were deduced. Thermal degradation of the grafted products was also studied by thermo-gravimetric analysis (TG) and differential thermo-gravimetry (DTG).
Abstract: Polybag and mulch film in agricultural field are used plastics which caused environmental problems after transplantation and planting processes due to the discarded wastes. Thus a degradable polybag was designed in this study to replace non degradable polybag with natural biodegradable resin that is widely available, namely sago starch (SS) and polyvinyl alcohol (PVA). Hybrid blend consists of SS, PVA and linear low density polyethylene (LLDPE) was compounded at different ratios. The thermal and mechanical properties of the blends were investigated. Hybrid films underwent landfill degradation tests for up to 2 months. The films showed gelation and melting transition existed for all three systems with significant melting peaks by LLDPE and PVA. All hybrid blends loses its LLDPE semi crystalline characteristics as PVA and SS systems had disrupted crystallinity and enhanced the amorphosity of the hybrid system. Generally, blending SS with PVA improves the mechanical properties of the SS based materials. Tensile strength of each film was also decreased with the increase of SS contents while its modulus had increased with SS content.
Abstract: Soil tillage systems can be able to influence soil compaction, water dynamics, soil temperature and crop yield. These processes can be expressed as changes of soil microbiological activity, soil respiration and sustainability of agriculture. Objectives of this study were: 1 - to assess the effects of tillage systems (Conventional System (CS), Minimum Tillage (MT), No-Tillage (NT)) on soil compaction, soil temperature, soil moisture and soil respiration and 2- to establish the effect of the changes on the production of wheat, maize and soybean. Five treatments were installed: CS-plough; MT-paraplow, chisel, rotary grape; NT-direct sowing. The study was conducted on an Argic-Stagnic Faeoziom. The MT and NT applications reduce or completely eliminate the soil mobilization, due to this; soil is compacted in the first year of application. The degree of compaction is directly related to soil type and its state of degradation. The state of soil compaction diminished over time, tending toward a specific type of soil density. Soil moisture was higher in NT and MT at the time of sowing and in the early stages of vegetation and differences diminished over time. Moisture determinations showed statistically significant differences. The MT and NT applications reduced the thermal amplitude in the first 15cm of soil depth and increased the soil temperature by 0.5-2.20C. Water dynamics and soil temperature showed no differences on the effect of crop yields. The determinations confirm the effect of soil tillage system on soil respiration; the daily average was lower at NT (315-1914 mmoli m-2s-1) and followed by MT (318-2395 mmoli m-2s-1) and is higher in the CS (321-2480 mmol m-2s-1). Comparing with CS, all the four conservation tillage measures decreased soil respiration, with the best effects of no-tillage. Although wheat production at MT and NT applications, had no significant differences soybean production was significantly affected from MT and NT applications. The differences in crop yields are recorded at maize and can be a direct consequence of loosening, mineralization and intensive mobilization of soil fertility.
Abstract: SUVA (equivalent to UV254/DOC) value in raw water is a precursor for the formation of trihalomethane during chlorination at a water treatment plant. This study collected rapidly filtered water from an advanced water treatment plant for use in experiments on raw water. The removal rate of treating the trihalomethanes formation potential (THMFP) was conducted by using a biological activated carbon. The hydraulic retention time and SUVA loading were major factors in biological degradation tests. The results showed that biological powder-activated carbon (BPAC) lowered the average concentration of UV254 and value of SUVA in raw water. A removal efficiency of THMFP was present in the treatment of the three primary organic carbon items. These results highlighted the importance of the BPAC had an excellent treatment efficiency on THMFP.
Abstract: In maize growing technologies, tillage technological operations are the most time-consuming and require the greatest fuel input. Substitution of conventional tillage, involving deep ploughing, by other reduced tillage methods can reduce technological production costs, diminish soil degradation and environmental pollution from greenhouse gas emissions, as well as improve economic competitiveness of agricultural produce.
Experiments designed to assess energy and environmental aspects associated with different reduced tillage systems, applied in maize cultivation were conducted at Aleksandras Stulginskis University taking into account Lithuania’s economic and climate conditions. The study involved 5 tillage treatments: deep ploughing (DP, control), shallow ploughing (SP), deep cultivation (DC), shallow cultivation (SC) and no-tillage (NT).
Our experimental evidence suggests that with the application of reduced tillage systems it is feasible to reduce fuel consumption by 13-58% and working time input by 8.4% to nearly 3-fold, to reduce the cost price of maize cultivation technological operations, decrease environmental pollution with CO2 gas by 30 to 146 kg ha-1, compared with the deep ploughing.