Periodica Polytechnica (Budapest University of Technology and Economics)
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Bandwidth Enhancement of a Current Sensing Trace by Adaptive Inverse Filtering
Full text linkIn our previous article we proposed a novel current measurement technique, the CSRTRI (Current Sensing by Real-Time Resistance Identification), which is characterized by the main principle of the in-situ identification of the current rail's resistance by an auxiliary inductive coil in the face of continuously varying conductor-temperature. The feasibility of the method was shown, and an accuracy of 0.93%...1.10% was demonstrated. The accuracy is limited by the stray inductance of the Cu-trace, which in combination with the resistance forms a temperature dependent highpass filter. We introduced an analog RC-lowpass filter based compensation method at 25°C nominal temperature and reached a bandwidth of 2 MHz. In this paper, we present an adaptive digital inverse filtering based compensation method instead. The advantage of this approach is that it covers the whole temperature range of the sensor, not just a narrow nominal value. The enhancement does not require any additional temperature sensor; we will utilize the instantaneous estimate of the copper trace’s resistance from the CSRTRI-algorithm directly to identify the cutoff frequency of the parasitic highpass filter in situ, without the need to determine the copper temperature itself. A temperature dependent time-varying first order lowpass filter of approximately 48 kHz cutoff frequency is applied to eliminate the main inductive overshoots. By this software-based transfer function enhancement a 1.5 MHz overall system bandwidth has been achieved between 20°C and 50°C conductor-temperature
Az ISBDM, avagy az ISBD megújulása
No full textThe IFLA Library Reference Model (IFLA LRM) plays a very important role in the field of cataloguing. One of the proofs of this is the International Standard Bibliographic Description for Manifestation (ISBDM), which is an implementation of the IFLA Library Reference Model for ISBD. ISBDM focuses on entity-based cataloguing. It provides stipulations and guidance for the describing of a single bibliographic entity, the Manifestation entity, in a bibliographic universe of multiple entities. It also provides guidelines for the describing of a relationship between a manifestation and another manifestations and between a manifestation and another LRM entities. In this paper, we undertake to present the ISBD for Manifestation draft and its elements, furthermore to show, through an example, how to describe the manifestation, that embodies of a work of fiction, and that is published in single unit.Az IFLA könyvtári referenciamodell (IFLA Library Reference Model, IFLA LRM) a katalogizálás területén igen jelentős szerepet tölt be. Ennek egyik bizonyítéka az ISBD for Manifestation (International Standard Bibliographic Description for Manifestation, ISBDM), ami nem más, mint az ISBD átalakítása az IFLA referenciamodell alapján. Az ISBDM az entitás alapú katalogizálást helyezi a középpontba, mégpedig úgy, hogy a több entitásból álló bibliográfiai univerzumban egyetlen entitás, a megjelenési forma entitás leírására vonatkozó előírásokat, útmutatásokat adja meg, továbbá megadja azokat a szabályokat is, amelyek megjelenési forma és más megjelenési forma illetve megjelenési forma és más LRM entitás közötti kapcsolatra vonatkoznak. E tanulmányban arra vállalkozunk, hogy bemutassuk az ISBD for Manifestation tervezetet és az azt felépítő elemeket, valamint egy példán keresztül megnézzük, hogyan tudunk egy egységben megjelenő, szépirodalmi művet megtestesítő megjelenési formát leírni
Enhancing Biohydrogen Yield and Slaughterhouse Wastewater Treatment Efficiency through Microalgae and Bacterial Synergy
Full text linkSlaughterhouse wastewater is highly rich in organic content. It carries an extremely high nutrient load when discharged into the environment, demonstrating that conventional treatment practices usually need to be more sustainable and extremely energy intensive. This research study probes various ways to integrate a microalgae-based platform to realize sustainable biohydrogen production, concurrently addressing critical wastewater treatment and renewable energy generation. A new two-stage cultivation method was developed using native wastewater bacteria and carbohydrate-rich microalgae, Chlorella vulgaris ESP 6. This method increased the efficiency of nutrient recovery and COD reduction compared to conventional single-stage systems. The microalgae, a key component in the process, efficiently converted the organic content of the wastewater into a carbohydrate-rich biomass, with a carbohydrate content of 48.8 ± 2.3%. This biomass was then fermented in the dark with Clostridium butyricum CGS5 to make biohydrogen after being treated with thermal acid. A pH control strategy through automatic operation was enforced, resulting in an impressive improvement in hydrogen production to 211 mL H2/g volatile solids and a maximum productivity of 39.11 mL/L/h, both competitive with the current literature. This study points out a promising way of replacing conventional wastewater treatment with integrated nutrient removal and energy recovery and utilizing wastewater biomass rich in carbohydrates as a renewable feedstock for biohydrogen production. Overall, this is the highest hydrogen yield ever reported on slaughterhouse wastewater and may be highly important for further development in waste-to-energy applications
Preparation and Adsorption Efficiency of Mango Waste-derived Biosorbents for Lead Removal in Water
Full text linkThe need to mitigate heavy metals contamination in the water environment using sustainable adsorbents has gain much attention recently due to compliance to sustainable development goals (SDGs) in the global context. This study explored the potential of Philippine mango (Mangifera indica L.) waste – specifically the peel, seed, and pit – as bioadsorbents for Pb2+ removal from synthetic wastewater. The bioadsorbents were prepared through drying and grinding, followed by chemical modification with HNO3 and NaOH. Characterization using Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) revealed surface functional groups and structural changes. Adsorption capacity was quantified using atomic absorption spectroscopy (AAS), and batch experiments were conducted with UV-Vis spectrophotometry. The untreated mango seed (UMSD) exhibited the highest Pb2+ adsorption capacity, exceeding 42.10 mg/g. Adsorption efficacy increased with higher initial Pb2+ concentrations, with untreated seed outperforming modified variants. Kinetic studies indicated rapid lead uptake, reaching equilibrium within 30 min. The adsorption data were best described by the Langmuir isotherm model, suggesting monolayer adsorption, while pseudo-second-order kinetics indicated that chemical bonding was the dominant mechanism. These results underscore the potential of UMSD as a cost-effective and sustainable bioadsorbent for lead removal in wastewater treatment, particularly in the Philippines
SCAPS Modeling and Improvement of the Characteristics of Cu/ZnO/P3HT/Pt Hybrid Solar Cells with Inorganic Electron Transport Layer
Full text linkThis study presents a thorough optimization approach for Cu/ZnO/P3HT/Pt hybrid solar cells (HSCs), providing insights into the interactions of several crucial parameters. Significant performance improvements are attained by carefully adjusting the absorber and electron transport layer (ETL). Enhancement of open-circuit voltage (VOC) and reduction in recombination represent principal mechanisms by which precise aluminum doping in ZnO contributes to increased power conversion efficiency (PCE). In our simulations, an aluminum doping concentration of 4% in ZnO, an ETL thickness optimized at 0.004 µm, and an electron affinity set to 4.25 eV (the energy released when an electron binds to a neutral atom or molecule) together improve the PCE.A critical finding is the identification of an optimal absorber layer thickness (2.5 µm), which achieves a maximum PCE of 16.82%. An examination of the interface fault density revealed a critical threshold of 1013 1/cm2, above which the performance started to decline quickly. The ideal operating point is found to be 313 K based on temperature-dependent research, with a peak PCE of 17.13%. Integrating advanced current-voltage characterization, innovative band alignment studies, and comprehensive temperature-dependent analyses, this work advances the theoretical framework for optimizing HSCs.This research opens new avenues for the rational design of high-efficiency photovoltaics and highlights the transformative potential of multiparameter optimization and interface engineering in next-generation solar technologies
Predictability Evaluation of Artificial Neural Networks and Response Surface Methodology Models for Thermo-physical Properties of Graphene Nanoplatelets–Ethylene Glycol/Water Nanofluids for Heat Transfer Applications
Full text linkIn this paper, the effectiveness of artificial neural networks (ANN) and response surface methodology (RSM) models in predicting the thermophysical properties ratio of graphene nanoplatelet (GNP)-ethylene glycol (EG)/water nanofluid has been discussed. Volume concentration (0.1%–0.5%) and temperature (−15 °C to 15 °C) were considered as inputs to train the models to predict the thermophysical properties ratios, including density, viscosity, thermal conductivity, and specific heat capacity. The ANN model with the Levenberg–Marquardt (trainlm) algorithm is used to get the best network by varying the number of 9 neurons in the hidden layer. In addition, an RSM, a three-dimensional surface plot techniques technique, was employed on the data points to obtain the new mathematical correlation for predicting thermophysical properties. Eventually, the mean squared error (MSE), regression coefficient (R2), and percentage of errors from both techniques were compared. The proposed ANN and RSM models show that the MSE, R2, and percentage of errors are 2.1239 × 10−5, 0.998, −1.42 to 1.28, and 0.761, above 0.945, −1.46 to 0.97, respectively. The results revealed both techniques are sorely suitable for predicting the thermophysical properties ratio of GNP-EG/water nanofluid
Vector Coupled Map Lattice PRNG for Monte Carlo Rendering
Full text linkIn this paper we propose a straightforward method to generate random points uniformly distributed on the unit sphere or following a 3D Gaussian distribution. For that, we use a small Coupled Map Lattice (CML), which is similar to a cellular automaton but with cells containing arbitrary variables in place of states from a finite set. Our lattice variables are 3D unit vectors. We use this setup to solve the otherwise challenging task of generating uniformly distributed direction vectors on the unit sphere without resorting to rejection sampling. We also generate samples of a 3D Gaussian distribution with sufficient accuracy by summing several of the above random vectors. To showcase the possible uses of this method, we introduce a new Bidirectional Reflection Distribution Function (BRDF) model that is physically plausible and features: perfect importance sampling, only needing a few intuitive parameters, not rejecting samples, and supporting anisotropy. The sampling process is generalized by projecting 3D Gaussian samples to 2D direction space. The resulting probability density function over directions is obtained in a closed form. We also demonstrate the capabilities of our lattice Pseudo-Random Number Generators (PRNG) by creating an especially fast Lambertian path tracer and a volumetric scattering effect
Effects of Location and Height of Vortex Generators on Aerodynamic Performance of NACA 4412 Airfoil
Full text linkThis study focuses on the aerodynamic effect of vortex generators (VGs) placed on the wing surface, with a focus on the height and chordwise position of the VGs. NACA 4412 airfoil was used for the investigation, which is a frequently used and well-researched airfoil in the aerospace industry, with a chord length (c) of 200 mm. Six different configurations have been analyzed with Computational Fluid Dynamics (CFD), with three chordwise positions (x) and two trailing edge heights (h). The results showed that VGs placed furthest from the leading edge (x/c = 20%) were able to increase lift and reduce drag to the greatest extent. In terms of height, the shorter (h/c = 0.5%) VGs produced the most lift. These results provide valuable insights as to how vortex generator design can be optimized for aerodynamic performance across various operating conditions
Companies' Ownership Structure and Humane Leadership
Full text linkA socially responsible company is expected to treat its employees in a humane way. We tested the hypotheses that a) the managers of familial businesses have a stronger humane orientation than the managers of non-familial businesses and b) a humane orientation has no negative effect on profitability. We conducted a questionnaire survey among managers in Hungarian manufacturing industry. A total of 197 managerial responses were received. We measured the humane orientation of the managers using the Leadership Competence Questionnaire module consisting of 36 items, which we grouped into the following factors beforehand: Self-efficacy, Performance motivation, Relationship orientation, Power motivation, Innovation, Openness. The group with the highest value for the humaneness factor was the group of highest productivity familial businesses. The ownership structure was found to have a greater influence on humane management than the domestic/foreign nature of the companies. At the same time, humane leadership was not typical for small businesses. We interpreted our results within the framework of situational leadership theory. A specific feature of this theoretical approach is that there is no single leadership style that can be said to be excellent, and that different leadership styles can be good if they are appropriate to the situation. We characterised leaders' relationship orientation as an indicator of humaneness, which is an effective leadership competence when used in appropriate situations
