Search
displaying 1000 best results Help
Search results for: Environmental analysis
-
cDNA fingerprint from the hepatopancreatic glands of pond snails (Lymnaea stagnalis) exposed to benzo[a]pyrene
PublicationIdentification of differentially expressed genes that could be potentially used as biomarkers of PAH exposure of common invertebrate animal (like freshwater snail) would be a valuable resource for investigators interested in toxicology and biomonitoring of aquatic environments. Therefore, the aim of this research was to investigate effects of waterborne benzo[a]pyrene (B[a]P) exposure on mRNA expression in the pond snail’s (Lymnaea...
-
Impact of influent wastewater quality on nitrogen removal rates in multistage treatment wetlands
PublicationNitrogen removal in treatment wetlands is influenced by many factors, and the presence of electron donors (biodegradable organic matter) and electron acceptors (nitrate ions) is the main limiting one; for obtaining these conditions, multistage treatment wetlands (MTWs) are required, where an extensive nitrification can be obtained in the first stages under aerobic conditions leaving then to the following anoxic/anaerobic stages...
-
Methods of Assessment of Metal Contamination in Bottom Sediments (Case Study: Straszyn Lake, Poland)
PublicationThe concentrations of six metals (Zn, Cu, Pb, Ni, Cr, and Cd) were investigated in bottom sediments of Straszyn Lake (North Poland). This study was designed to determine a total content of metals and to assess their mobility and bioavailability. The sequential extraction was used to fractionate metals into five fractions: exchangeable, bound to carbonates, bound to Fe–Mn oxides, bound to organic matter, and residual. The evaluation...
-
An optimal designed experiment for the alkaline hydrolysis of feather keratin
PublicationFeathers, burdensome waste from the poultry industry, can be a cheap source of keratin, a protein with excellent physico- chemical, biological, and mechanical properties. Acid and alkaline hydrolyses are usually adopted for isolation of keratin from its natural resources. This study aimed at assessing the statistically significant effect of input variables in the alkaline hydrolysis of keratin from chicken feathers on the process...
-
Jan Wajs dr hab. inż.
People -
Post-failure fracture surface analysis of notched steel specimens after bending-torsion fatigue
Publication -
Effect of multiaxial bending-torsion loading on fracture surface parameters in high-strength steels processed by conventional and additive manufacturing
Publication -
Fractal analysis of the bending-torsion fatigue fracture of aluminium alloy
Publication -
Thermal subjective sensations of motorcyclists
Publication -
A PAIR OF PERFECTLY CONDUCTING DISKS IN AN EXTERNAL FIELD
Publication -
A risk analysis of winter navigation in Finnish sea areas
Publication -
Reactive deposition of TiNx layers in a DC-magnetron discharge
PublicationTiNx layers have been deposited in 'balanced mode' and 'unbalanced mode' of a reactive DC-magnetron plasma (carrier gas argon, reactive gas nitrogen) under different conditions. Discharge power and reactive gas flow have been varied. The layers have been examined by X-ray photoelectron spectroscopy (XPS), X-ray reflectometry (XR), and spectroscopic ellipsometry (SE). The results of the layer analyses were combined with plasma investigations...
-
First-order impulsive functional differential equations
PublicationPraca dotyczy problemów istnienia rozwiązań i kwazi-rozwiązań dla równań różniczkowych rzędu pierwszego z impulsami i nieliniowymi warunkami brzegowymi. Operator występujący w zagadnieniu jest typu opóźnionego. Badano również nierówności różniczkowe z impulsami związane z zagadnieniem wyjściowym. Otrzymane wyniki zilustrowano na przykładach.
-
Non-destructive testing of industrial structures with the use of multi-camera Digital Image Correlation method
Publication -
Thermal properties of poly(vinyl chloride)/polyurethane blends
Publication -
Application of the DSC analysis of thermoplastic polyurethane elastomers to a comparative study of their technological properties
Publication -
Primary and secondary crystallization of poly(ethylene adipate)
Publication -
Dynamic mechanical thermal analysis of polyamide 6/thermoplastic polyurethane blends
Publication -
Thermal properties of polyamide 6/polyurethane blends
Publication -
Glass transition temperatures of polyurethane-urea elastomers based on N, N′-ethylenethiourea and N, N′-ethyleneurea as chain extenders
Publication -
Crystallization kinetics of poly(ethylene adipate) investigated by differential scanning calorimetry
Publication -
Bisquare robust polynomial fitting method for dimple distortion minimization in surface quality analysis
Publication -
Proposal of frequency‐based decomposition approach for minimization of errors in surface texture parameter calculation
Publication -
Threat/risk assessment tool to assess vulnerability of Polish cities to Russian attacks
Publication -
QSRR Evaluation of the New Anticancer Sulfonamides in View of the cis-trans Isomerism
Publication -
Biological Activity of Compounds Exhibiting Local Anesthetics's Properties Evaluated by QSAR Approach
Publication -
Failure analysis and modernization of high-pressure hydraulic press for drilling tubes testing
Publication -
Thermodynamics of the thermal decomposition of calcium oxalate monohydrate examined theoretically
Publication -
Theoretical methods in thermodynamics of condensed phases
Publication -
Theoretical prediction of enthalpies and temperatures of sublimation of organochlorine compounds including pesticides
Publication -
On Nonlinear Volterra Integral Equations With State Dependent Delays in Several Variables
PublicationW pracy badane jest istnienie i jednoznaczność rozwiązań nieliniowego równania całkowego typu Volterry z opóźnionym argumentem zależnym od funkcji niewiadomej wielu zmiennych. Poszukiwane są ciągłe rozwiązania lipschitzowskie. Rozwiązania są poszukiwane metodą porównawczą z zastosowaniem twierdzenia Banacha o punkcie stałym.
-
Stable and unstable bifurcation in the von Karman problem for a circular plate
PublicationW niniejszej pracy badamy równania von Karmana dla cienkiej, sprężystej, kołowej płyty, która znajduje się na sprężystym podłożu, pod działaniem sił ściskających wzdłuż swojego brzegu.Stosując metody analizy nieliniowej, dowodzimy istnienia stabilnychi niestabilnych punktów bifurkacji w zbiorze rozwiązań badanych równań.
-
Differential inequalities with initial time difference.
PublicationUzyskano pewne wyniki porównawcze pomiędzy rozwiązaniami nierówności różniczkowych startujących z różnych punktów początkowych. O nieliniowej funkcji f (związanej z zagadnieniem) zakładano jednostronny warunek Lipschitza. Podano pewne zastosowanie otrzymanych wyników. Sformułowano też pewne warunki dotyczące stabilności.
-
A framework for risk matrix design: A case of MASS navigation risk
PublicationRisk matrix, a tool for visualizing risk assessment results, is essential to facilitate the risk communication and risk management in risk-based decision-making processes related to new and unexplored socio-technical systems. The use of an appropriate risk matrix is discussed in the literature, but it is overlooked for emerging technologies such as Maritime Autonomous Surface Ships (MASS). In this study, a comprehensive framework...
-
The effect of elevated temperature on LCF damage growth in 2024AA – Experiment and modeling
PublicationThis paper presents the results of experimental low-cycle fatigue (LCF) tests conducted on EN-AW 2024 alloy in T3511 temper at 100 ◦C, 200 ◦C and 300 ◦C. The material’s basic fatigue characteristics were determined, such as fatigue life curve and cyclic strain curve. Both the hysteresis loop and nature of fracture surfaces obtained in macro- and microscopic observations (scanning electron microscope, SEM) were accounted for. The...
-
Damage of a post-tensioned concrete bridge – Unwanted cracks of the girders
PublicationThe cracking of a post-tensioned T-beam superstructure, which was built using the incremental launching method, is analyzed in the paper. The problem is studied in detail, as specific damage was observed in the form of longitudinal cracks, especially in the mid-height zone of the girder at the interface of two assembly sections. The paper is a case study. A detailed inspection is done and non-destructive testing results of the...
-
Case study of masts damage of the sail training vessel POGORIA
PublicationArtykuł przedstawia opis i analizę przyczyn zdarzenia polegającego na utracie masztów w lipcu 2009 przez barkentynę sts ''POGORIA'' w trakcie regat Tall Ships Race 2009. Przedstawiono podstawowe okoliczności stanowiące tło zdarzenia, dokonano anlizy przyczyn w skali globalnej, zaprezentowano analizę szczegółową utraty nośności konstrukcji stalowej, a na tym tle wypunktowano szczegółowe przyczyny leżące u źródeł wypadku. We wnioskach...
-
Calculations of notch stress factor of a thin-walled spreader bracket fillet weld with the use of a local stress approach
PublicationPresence of geometric notches in welded joints causes concentration of strains and stresses, therefore reducing fatigue strength of such joints. This article presents an analysis of stress concentrations in a fillet weld of a spreader mounting bracket on a small sailing yacht. The aim of this article is to direct the attention of designers, manufacturers and regulatory bodies to issues of fatigue cracks that form in brackets fastening...
-
Analysis of Interspike-Intervals for the General Class of Integrate-and-Fire Models with Periodic Drive
PublicationWe study one-dimensional integrate-and-fire models of the general type x˙=F (t, x) and analyze properties of the firing map which iterations recover consecutive spike timings. We impose very week constraints for the regularity of the function F (t, x), e.g. often it suffices to assume that F is continuous. If additionally F is periodic in t, using mathematical study of the displacement sequence of an orientation preserving circle...
-
Application of multisine nanoscale impedance microscopy to heterogeneous alloy surface investigations
PublicationIn the recent years atomic force microscopy is recognized as valuable tool for investigation of surficial features of construction materials. It concerns, among other things, studies of changes caused by such phenomena as galvanic corrosion, passivation associated with the growth of oxide layers, or sensitization of austenitic steels with the formation of carbide phases. In addition, atomic forcemicroscopy allows easy coupling...
-
Solving Boundary Value Problems for Second Order Singularly Perturbed Delay Differential Equations by ε-Approximate Fixed-Point Method
PublicationIn this paper, the boundary value problem for second order singularly perturbed delay differential equation is reduced to a fixed-point problem v = Av with a properly chosen (generally nonlinear) operator A. The unknown fixed-point v is approximated by cubic spline vh defined by its values vi = vh(ti) at grid points ti, i = 0, 1, ... ,N. The necessary for construction the cubic spline and missing the first derivatives at the boundary...
-
Systems of differential equations with a singular matrix
PublicationPraca dotyczy układów równań różniczkowych z macierzą osobliwą. Szczególnymi przypadkami takich układów są równania różniczkowo-algebraiczne. Korzystając z odpowiedniej nierówności różniczkowej dla układów równań i metody quasi linearyzacji pokazano, iż odpowiednie monotoniczne ciągi są zbieżne do rozwiązania naszego problemu i jest to zbieżność kwadratowa. O funkcji f występującej po prawej stronie zagadnienia zakładano...
-
Fractographic-fractal dimension correlation with crack initiation and fatigue life for notched aluminium alloys under bending load
PublicationIn this study, fatigue fracture surfaces of aluminium alloy 2017-T4 notched specimens were investigated under cyclic bending to find an alternative failure loading index.. The surface topographies were measured on the entire fracture area with an optical profilometer for different loading conditions. Fatigue crack initiation life Ni and total fatigue life Nf were examined using standard surface topography parameters (such as, root...
-
The fracture behaviour of notched PMMA specimens under simple loading conditions – Tension and torsion experimental tests
PublicationThis paper presents the results of experimental testing of flat PMMA specimens during uniaxial loading conditions. Two separate tests were conducted: tensile and torsion. The specimens were weakened with V-type edge notches with different root radii: 0.5; 2 and 10 mm. The specimens were made in two thickness variants: 5 and 15 mm. Monotonic tensile and torsion tests were carried out while keeping the averaged strain rate constant,...
-
An image processing approach for fatigue crack identification in cellulose acetate replicas
PublicationThe cellulose acetate replication technique is an important method for studying material fatigue. However, extracting accurate information from pictures of cellulose replicas poses challenges because of distortions and numerous artifacts. This paper presents an image processing procedure for effective fatigue crack identification in plastic replicas. The approach employs thresholding, adaptive Gaussian thresholding, and Otsu binarization...
-
FEM simulations applied to the failure analysis of RC structure under the influence of municipal sewage pressure
PublicationThe paper discusses a failure mechanism of reinforced concrete (RC) structure with steel cover that failed under the influence of municipal sewage pressure. To explain the reasons of failure, in-situ measurements, laboratory experiments and comprehensive Finite Element Method (FEM) computations were performed. Non-destructive in-situ scanning tests were carried out to determine quantity and cover thickness of embedded reinforcement...
-
Corrigendum to “An investigation on residual stress and fatigue life assessment of T-shape welded joints” [Eng. Fail. Anal. 141 (2022) 106685]
PublicationThis paper aims to quantitatively evaluate the residual stress and fatigue life of T-type welded joints with a multi-pass weld in different direction. The main research objectives of the experimental test were to test the residual stress by changing direction along with multiple wielding passes and determine the fatigue life of the welded joints. The result shows that compressive residual stress increases in the sample gradually...
-
Advanced Bayesian study on inland navigational risk of remotely controlled autonomous ship
PublicationThe arise of autonomous ships has necessitated the development of new risk assessment techniques and methods. This study proposes a new framework for navigational risk assessment of remotely controlled Maritime Autonomous Surface Ships (MASS). This framework establishes a set of risk influencing factors affecting safety of navigation of a remotely-controlled MASS. Next, model parameters are defined based on the risk factors, and...
-
A brief note on entire fracture surface topography parameters for 18Ni300 maraging steel produced by LB-PBF after LCF
PublicationThe concept of entire fracture surface investigation is helpful in explaining fatigue phenomena. In this paper, this method has been applied for 18Ni300 maraging steel using a 3D measurement system. Before post-mortem analysis, the specimens produced by laser beam powder bed fusion (LB-PBF) were tested under low-cycle fatigue (LCF) for eight strain amplitudes in the interval 0.3% to 1.0%. The attention was placed on the relationship...
-
An investigation on residual stress and fatigue life assessment of T-shape welded joints
PublicationThis paper aims to quantitatively evaluate the residual stress and fatigue life of T-type welded joints with a multi-pass weld in different direction. The main research objectives of the experimental test were to test the residual stress by changing direction along with multiple wielding passes and determine the fatigue life of the welded joints. The result shows that compressive residual stress increases in the sample gradually...