Search Results (11)

The purpose of the experiment was to indicate which element of the production process of flexible printed circuit boards is optimal in terms of the reliability of final products. According to the Taguchi method, in the experiment, five factors with two levels each were chosen for the subsequent analysis. These included the number of conductive layers, the thickness of the laminate layer, the type of the laminate, the diameter of the plated holes, and the current density in the galvanic bath. The reliability of the PCBs in the produced variations was verified using the Interconnect Stress Test environmental test. The qualitatively best variant of the board construction was indicated using the signal-to-noise ratio and the analysis of variance method for each factor. The factors determined to be the most important in terms of reliability were the number of conductive layers and the current density in the galvanic bath. The optimal variant of the board construction was two conductive layers on a polyimide laminate, where the laminate layer was 100 μm thick, the hole diameter was equal to 0.4 mm, and current density was 2 A/dm² in the galvanic bath. Therefore, the plated experiment indicated the factors needed to obtain a high-quality product with a low failure rate. Full article

Taking care of water resources and minimizing water losses in water supply networks requires a broad approach to identifying and neutralizing operational problems. The correct selection of water meters to minimize apparent losses requires knowledge of the characteristic flows that may occur in the facility to which water is supplied. The research aimed to develop tools in the form of mathematical models and water consumption curves along with hourly water consumption coefficients to facilitate the process of selecting water meters for engineers and creating computer models of water supply systems. The research involved monitoring the flow of 76 single-family and multi-family buildings in four towns in Poland, followed by data analysis and development of tools supporting the selection of water meters and the construction of computer models of water distribution networks. High correlation coefficients of the studied variables indicate the results’ usefulness. Four models were developed to determine the maximum flow values in multi-family buildings (three models) and single-family buildings (one model) in the range of water meter diameters DN15-DN40. Characteristics of the average hourly peak coefficient (HPC) values were also developed, along with the range of changes in HPC values for single-family and multi-family buildings. Full article

The primary objective of this research was to assess the efficacy of a novel solution under conditions closely resembling those of real-world scenarios. Biological beds, or filters, hold significant potential for widespread implementation in individual households, particularly in areas with dispersed housing. The system’s aim was to improve the quality of wastewater treated in on-site domestic biological treatment plants. A pivotal aspect of the project involved developing a prototype research installation for conducting comprehensive testing. Our installation system consisted of several components designed to create a laboratory-scale model for domestic wastewater treatment. The model comprised four biological reactors filled with ABS material and secured by a PUR frame. Additionally, the tested model included a controller for wastewater dosing control, a septic tank as a reservoir, and four tanks for collecting purified wastewater. Through regression analysis using the Generalized Linear Model (GLM), a correlation between COD_Cr and TSS was revealed. This study presents the research findings concerning the development of a prototype installation that incorporates an advanced reactor or filter. The data derived from this research have the potential to contribute to the creation of products that enhance the performance and efficiency of household wastewater treatment systems. Full article

The increase in electricity generation prices represents a reason why water utility companies are looking for ways to reduce costs. One of the first ideas of users was to build photovoltaic installations. Water treatment plants or sewage treatment plants usually have large unused areas. They look different in facilities that consume a lot of energy but occupy little land, and include water intakes (wells) and water pumping stations. Facilities equipped with pumps are characterized by high electricity consumption. This article assesses the possibility of using PV installations at the water intake. An analysis of energy production from the 3.0 kW PV installation in Polanica-Zdrój was carried out, and then, simulations of the possibility of providing energy via installations with capacities of 3.0 kW, 4.2 kW, and 6.0 kW were performed. Analyses of energy production and demand, as well as analyses of water production based on annual, monthly, daily, and hourly data, were performed. An analysis of the hourly coverage of the WPS’s demand for electricity was carried out with regard to the current production of energy from the PV installation, as was an analysis of the overproduction of energy from the PV installation regarding the energy demand of the WPS. The simulation results are presented for cloudy and sunny days. Full article

Household wastewater is a problem, especially in areas with a dispersed settlement where there is no wastewater collection system or wastewater treatment plant. In this case, it is necessary to build a local or onsite wastewater treatment plant. This paper is an attempt to analyse the possibility of using recycled shredded ABS plastic (acrylonitrile butadiene styrene) as packing media in an experimental vertical flow filter for use in on-site wastewater treatment plants. Studies have shown that shredded recycled ABS is a promising filtration material that has several features important in the treatment process, like a large surface area, high mechanical strength and chemical inertness. The system was operated with a hydraulic load of 50 dm³/m² (3 months). BOD5 (biochemical oxygen demand), COD (chemical oxygen demand), and total suspended solids (TSS) reduction efficiency in the primary effluent was high; 94.4%, 77.8%, and 92.8%, respectively. Full article

Technical system (TS) models are widely used for setting and solving problems for the improvement of biomedical engineering systems beyond simple parameter optimisation. They mostly focus on system elements, the change or replacement of which can provide significant technical and economic benefits. The natures of TS models and their methods of construction vary, but they all share several common features: a functional approach, a focus on the conflicting demands put on the particular elements of a system or their interactions, and the construction of models that assume the significance of those conflicts. Thus, modelling aims to visualise conflicts in a way that facilitates the setting and solving of tasks that lead to their elimination. Such modelling can be termed problem-oriented. Results of the analysis of problem-oriented models proposed by different authors have shown that they model the structure of problem functions or the structure of the TS fragments responsible for such functions. A graphic representation of these models allows for the comparison and identification of opportunities for further development and aggregation. In this paper, the joint application of several known and proposed models is suggested for efficient forecasting of biomedical engineering systems and their modernisation. Full article

Liming surface water is a fairly popular method of increasing the pH values and decreasing the concentration of phosphates and heavy metals. According to the Environmental Protection Agency (EPA) recommendations, the increase of water pH should not exceed 1.5. If surface water is the source of water supply, liming is a process that reduces water contamination. This should prevent the creation of an additional load for the water treatment plants in urban settlements. This article is an interdisciplinary research study aiming to (1) determine and compare the doses of new dispersed, thermally activated limestone and natural limestone, (2) find the relation between dose value and initial water parameters (pH, Eh and total mineralization), and (3) create an artificial neural network (ANN) model to predict changes in water pH values according to EPA recommendations. Recommended doses were obtained from experimental studies, and those of dispersed, thermally activated limestone were lower than the doses of natural limestone. Neural networks were used to predict the changes in water pH values when adding different doses of limestone with different initial water parameters using the ANN model. Four ANN models with different activation functions and loss function optimizers were tested. The best results were obtained for the network with the ReLU activation function for hidden layers of neurons and Adam’s loss function optimizer (MAPE = 14.1%; R² = 0.847). Further comparison of the results of the loss function and the results of calculating the quality metric for the training and validation dataset has shown that the created ANN can be used to solve the set research issue. Full article

The paper presents results of investigations of influence of major head losses on exploitation properties of water supply pipes after 30-year exploitation. The tested materials were cast-iron pipes with the internal diameter of 150 mm. A flowability drop coefficient η_t with average value of 0.45 was determined. Using the measured values of pressure difference Δp determined the absolute roughness of internal walls of the pipes after 30-year exploitation, which was referred to the new pipelines. The absolute roughness for the exploited pipes was equal to k = 27.6 mm, whereas for the new ones it was significantly lower and equal to k = 0.9 mm. Additionally, an analysis of the chemical and mineral composition of sediments gathered in the investigated pipelines was also performed. The top layer of the sediments was dominated by the compounds of a character of the iron hydroxide: goethite (α-FeOOH) and lepidocrocite (γ-FeOOH), whereas the internal layer was supplemented by the gypsum and sulfur, which was proven by the investigations performed with the use of scanning electron microscope (SEM). The sediment gathered within the pipes is the main reason of ca. 30-fold increase of the absolute roughness, which resulted in the flowability drop of the exploited water supply pipes. Full article

The paper presents results of investigation of the local resistance coefficient ζ in welded polypropylene T-junctions with the internal diameter 13.2 mm. The investigations were performed on an independently constructed test rig. The scope of investigations encompassed the T-junctions, which were (1) properly warmed up and properly pressed, (2) poorly warmed up and poorly pressed, or (3) excessively warmed up and excessively pressed. The local resistance coefficients ζ determined by measurements according to the standard PN-EN 1267:2012(Designation of the Polish Standard) were compared to those determined with use of the nomograms recommended for designing water supply systems and installations. Real values of the coefficients ζ, obtained in measurements were significantly higher than those read from the nomograms. The local resistance coefficients ζ in welded polypropylene T-junctions depend on water flow velocity and the manufacturing precision of a T-junction joint. Full article

The article presents the results of tests of minor head losses through PVC and PP elbows for a flow of water and mixtures of water and sand with grain sizes of up to 0.5 mm and concentrations of 5.6 g·L⁻¹, 10.84 g·L⁻¹, and 15.73 g·L⁻¹. The tests were carried out at variable flow velocities for three elbow diameters of 63 mm, 75 mm, and 90 mm. The flow rate, pressure difference in the tested cross-sections, and temperature of the fluids were measured and automatically recorded. The results of the measurements were used to develop mathematical models for determining the minor head loss coefficient as a function of elbow diameter, sand concentration in the liquid, and Reynolds number. The mathematical model was developed by cross validation. It was shown that when the concentration of sand in the liquid was increased by 1.0 g∙L⁻¹, the coefficient of minor head loss through the elbows increased, in the Reynolds number range of 4.6 × 10⁴–2.1 × 10⁵, by 0.3–0.01% for PP63, 0.6–0.03% for PP75, 1.1–0.06% for PP90, 0.8−0.01% for PVC63, 0.8–0.02% for PVC75, and 0.9–0.04% for PVC90. An increase in Re from 5 × 10⁴ to 2 × 10⁶ for elbows with diameters of 63, 75 and 90 mm caused a 7.3%, 6.8%, and 6.0% decrease in the minor head loss coefficient, respectively. Full article

The paper presents the analysis of results of empirical investigations of a negative pressure difference in vacuum pipelines with internal diameters of 57, 81, 102 mm. The investigations were performed in an experimental installation of a vacuum sewage system, built in a laboratory hall on a scale of 1:1. The paper contains a review of the literature concerning two-phase flows (liquid-gas) in horizontal, vertical and diagonal pipelines. It presents the construction and working principles of the experimental installation of vacuum sewage system in steady and unsteady conditions during a two-phase flow of water and air. It also presents a methodology for determination of formula for calculation of a negative pressure difference in vacuum pipelines. The results obtained from the measurements of the negative pressure difference Δp_vr in the vacuum pipelines were analyzed and compared with the results of calculations of the negative pressure difference Δp_vr, obtained from the determined formula. The values of the negative pressure difference Δp_vr calculated for the vacuum pipelines with internal diameters of 57, 81, and 102 mm with the use of Formula (19) coincide with the values of Δp_vr measured in the experimental installation of a vacuum sewage system. The dependence of the negative pressure difference Δp_vr along the length of the vacuum pipelines on the set negative pressure in the vacuum container p_vzp is linear. The smaller the vacuum pipeline diameter, the greater the negative pressure difference Δp_vr is along its length. Full article