1,456 research outputs found
Photovoltaic System Efficiency Enhancement With Thermal Management: Phase Changing Materials (pcm) With High Conductivity Inserts
No full textThe electrical conversion efficiency of photovoltaic cells from solar radiation heavily depends on the cell temperature. Here we propose a novel thermal management strategy to keep the cell temperature in the same order to attain maximum efficiency. The comparative study presented is based on four solar module configurations: a conventional photovoltaic module (PVT module), a conventional module with PCM layer underneath (PVT/PCM-I), a configuration where fins embedded into PCM (PVT/PCM-II), and configuration where the bottom of the PCM layer in PVT/PCM-II was cooled via convection (PVT/PCM-III). The developed 3D numerical model is solved via ANSYS software involving the solar ray tracing radiation model for incident solar radiations and a transient melting-solidification thermo-fluid model to cater for PCM phase transition. Results from the numerical model were validated via a comparison of experimentally studied results presented in the literature. After 120 minutes, results show that the conversion efficiency of PV cells becomes 16.84%, 18.65%, 18.83%, and 18.98% after 120 minutes for PVT module, PVT/PCM-I, PVT/PCM-II, and PVT/PCM-III with an inlet velocity of 3m/s, respectively. For the respective configurations, the specific electrical power per unit area produced reaches 75.30W/m2, 83.39W/m2, 84.19W/m2, and 89.42W/m2 for solar radiation of 540W/m2 and 26°C ambient temperature. Results reveal that a 5 mm increase in the fin height for PVT/PCM-II results in a 0.22% increase in efficiency while a 0.5m/s increase in the inlet velocity of the cooling air for PVT/PCM-III results in about 0.06% increase in efficiency. © 2021, ilhami Colak. All rights reserved
Modeling of a smart grid system using real time data on NEPLAN
No full textThe simulation model of the Smart Grids Laboratory of the Institute of Energy and Transport is presented in this paper and a day of its operation is analyzed. The developed model simulates six different modules (a photovoltaic array, a Li-ion battery storage system, a small wind turbine, a diesel generator, a laboratory load and the connection point with the grid). The modules are connected radially at a common bus
Proceedings of World Academy of Science Engineering and Technology
No full textThe wavelet transform is one of the most important method used in signal processing. In this study, we have introduced frequency-energy characteristics of local earthquakes using discrete wavelet transform. Frequency-energy characteristic was analyzed depend on difference between P and S wave arrival time and noise within records. We have found that local earthquakes have similar characteristics. If frequency-energy characteristics can be found accurately, this gives us a hint to calculate P and S wave arrival time. It can be seen that wavelet transform provides successful approximation for this. In this study, 100 earthquakes with 500 records were analyzed approximately
Comparative analysis of on-load tap changing (OLTC) transformer topologies
No full textOld - EWI-ESE-DC&S DC systems & StorageElectrical Power Processin
The water-soluble zwitterionic and cationic tetra-substituted zinc(II) phthalocyanines: Synthesis, photophysical, photochemical and protein binding properties
No full textThe synthesis and characterization of tetra-(2-EN-((3-dimethylamino)propyl)carbamate]oxyethyl} substituted zinc(II) phthalocyanine (ZnPc) and its sulfobetaine (S-ZnPc), betaine (B-ZnPc), N-Oxide (N-ZnPc) and cationic (Q-ZnPc) derivatives were described in this study. All novel phthalocyanines were characterized by UV-Vis, FT-IR, H-1 NMR, mass spectroscopic techniques and elemental analysis as well. The solubility of these phthalocyanines was enhanced in polar solvents and aquatic media by the conversion of amidoamine groups on the substituents to the zwitterionic sulfobetaine, betaine, N-Oxide, and quaternary ammonium counterparts which make them promising candidates for treatment of cancer via photodynamic therapy (PDT) method. Although the photophysical and photochemical properties of newly synthesized tetra-{2-[N-((3-dimethylamino)propyl)carbamateloxyethyl} substituted zinc(II) phthalocyanine (ZnPc) was investigated in DMSO, its zwitterionic and cationic derivatives were examined in both DMSO and aqueous solutions. The binding behavior of zwitterionic and cationic zinc(II) phthalocyanines were investigated by bovine serum albumin (BSA) protein in aqueous solutions for determination of transportation abilities of these phthalocyanines in the blood. (C) 2016 Elsevier Ltd. All rights reserved
Statistical modeling of Chevreul's salt recovery from leach solutions containing copper
No full textIn this study, oxidized copper ore was dissolved under optimum conditions [temperature 14 degrees C, average particle size 2.8 mm, stirring speed 500 rpm, ammonia concentration 2.824 mol L-1, ammonium sulphate concentration 0.236 mol L-1, solid-to-liquid ratio 0.167 g mL(-1), leaching time 2 h] in an aqueous NH3-(NH4)(2) SO4 solution [T. Calban, S. Colak, M. Yesilyurt, Optimization of leaching of copper from oxidized copper ore in NH3-(NH4)(2)SO4 medium, Chem. Eng. Commun., in press]. Chevreul's salt was precipitated by passing SO2 from these leach solutions. Chevreul's salt, a mixed valence copper sulfite Cu2SO3 center dot CuSO3 center dot 2H(2)O, was characterized by XRD and SEM. The effects of parameters, such as temperature, pH, stirring speed and reaction time, were investigated on precipitation of Chevreul's salt. 2" factorial experimental design and orthogonal central composite design methods in the precipitation experiments were used. It was observed that the most effective parameters on the precipitation of Chevreul's salt were temperature, stirring speed and reaction time. The optimum conditions established for maximum copper precipitation were: temperature 62 degrees C, pH 3, stirring speed 600 rpm, reaction time 12 min. Fixed parameters chosen at the initial stage of the reaction were: SO2 flow rate 358 L h(-1), concentration of CuSO4 solution 7.383 g Cu L-1. Under these optimum conditions, the percentage of copper precipitated from leach solution was 99.92. (c) 2005 Elsevier B.V. All rights reserved
Investigation of the photophysical and photochemical properties of peripherally tetra-substituted water-soluble zwitterionic and cationic zinc(II) phthalocyanines
No full textIn this study, 4-{4-[N-((3-dimethylamino)propyl)amide]phenoxy}phthalonitrile (1) and its zinc(II) phthalocyanine derivative (2) were synthesized for the first time. 4-(N-((3-Dimethylamino)propyl)amide)phenoxy substituted zinc(II) phthalocyanine (2) was converted to its water-soluble sulfobetaine (3), betaine (4) and N-oxide (5) containing zwitterionic and quaternized cationic (6) derivatives. All newly synthesized compounds (1-6) were characterized by the combination of UV-vis, FT-IR, H-1 NMR, mass spectroscopy techniques and elemental analysis. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen quantum yields) properties were investigated in DMSO for all the synthesized zinc(II) phthalocyanines (2-6) and in both DMSO and aqueous solutions for zwitterionic and cationic phthalocyanines (3-6) for the specification of their capability as photosensitizers in photodynamic therapy (PDT). The binding behavior of water soluble phthalocyanines (3-6) to the bovine serum albumin protein was also examined for the determination of their transportation ability in the blood stream
Tetrakis{2-[N-((3-morpholino)propyl)carbamateloxyethyl} zinc(II) phthalocyanine and its water soluble derivatives: Synthesis, photophysical, photochemical and protein binding properties
No full textIn this study, the novel water soluble derivatives of 2-[N-((3-morpholino)propyl)carbamate]oxyethyl substituted zinc(II) phthalocyanine (1) bearing different type of groups such as sulfobetaine (2), betaine (3), N-Oxide (4) and quaternized methyl (5) on the morpholine core were synthesized for the first time. All newly synthesized zinc(II) phthalocyanine derivatives were characterized by different spectroscopic techniques such as UV-vis, FT-IR, H-1 NMR, mass and elemental analysis as well. They showed excellent solubility in aqueous media due to their zwitterionic and ionic characters which makes them promising candidates for treatment of cancer by photodynamic therapy (PDT). The photophysical and photochemical properties were investigated in DMSO for tetrakis(2-[N-((3-morpholino)propyl)carbamate]oxyethyl} substituted zinc(II) phthalocyanine (1) and in both DMSO and water+Triton X-100 solutions for its water soluble ionic derivatives (2-5). The binding behaviors of ionic zinc(II) phthalocyanines by bovine serum albumin (BSA) protein were investigated for determination of transportation ability of these phthalocyanines in the blood circulation. (C) 2016 Elsevier B.V. All rights reserved
Organisering av ekonomiskt bistånd – Perspektiv på en integrerad och en specialiserad kommun
No full textAuthor: Merima Colak Title: Organization of financial assistance - Perspective on an integrated and a specialized municipality [translated title] Supervisor: Håkan Johansson Assessor: Staffan Blomberg The purpose of this study was to examine how specialized and integrated social services manage their social assistance. In addition to this the aim was to examine how social workers and officials working within these two forms of organizations experience discretion. Furthermore, a goal of this paper was also to examine if the social workers felt that any of these two organizational forms had any impact on the workload and how that in such case manifested. The study was conducted through a qualitative research method. Six social workers and officials were interviewed for the study. The results from the study demonstrated that the employees in the integrated organization had more general work tasks and that those in the specialized organization had their tasks divided on different units that were more specialized. Findings also showed that employees in each municipality interpret discretion differently. The social workers from the integrated organization interpreted discretion in terms of being able to affect their client’s case. The social workers from the specialized organization, on the other hand, defined discretion as being able to influence their own daily work tasks. Conclusively, the study showed that workload exists in both municipalities and that it was manageable in each of the municipalities, the workload was however higher in the specialized one but it was no burden on the employees in neither the specialized nor the integrated. Key words: Discretion, organizational structure, integrated and specialized organizations, social assistance, workload. Key words: handlingsutrymme, organisationsstruktur, integrerade och specialiserade organisationer, ekonomiskt bistånd, arbetsbelastning
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