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This thesis deals with the analysis of the family policies in Finland, Sweden and Norway. The focus is on policies for families with children below the age of three years concerning day care and social services and benefits for parents. Thus, child benefit, child-related leave and home care allowance are in the centre of this thesis. The aspects of the welfare development, facts about their societies, as well as current challenges, complement this thesis. Eventually, the final analysis of the Nordic family policies is considered in an international comparison, focusing on Germany’s contextual issues.
This thesis endeavours to show the connection between women’s rights and international social work.
The goal is to bring more awareness about women’s rights and international social work to the reader and offer an introduction and a brief overview to numerous essential terms and areas connected to women’s rights and international social work. The thesis has following four chapters: Theoretical Embedding, Political Framework, International Social Work and women’s human rights and Challenges – Case studies
Application of Induction Thermography for Detection of Near Surface Defects in Steel Products
(2020)
untitled document
(2020)
This paper describes the modelling, simulation and energy management of a fuel cell hybrid heavy-duty truck. For this purpose, a longitudinal dynamic model of a 26t truck was set up and the load requirement for the drive train was determined based on a driving cycle. To meet this load requirement as efficiently and dynamically as possible three different energy management strategies were implemented, tested and the impact on the overall system was analysed. In addition, the behaviour of the hybrid system with the various energy management strategies with different battery capacity is shown and analysed.
Our current mobility paradigm increasingly faces economic, ecological, and social limits in urban areas. The aim of this paper is to analyse if a fleet of shared autonomous electric vehicles (AEVs) can meet these challenges while satisfying the current requirements of privately-owned internal combustion engine vehicles (ICEVs). Therefore, analytical models have been developed to simulate and investigate the impacts of mobility behaviour in Berlin and Stuttgart (Germany). The collected data were used to calculate the fleet size, the energy consumption, the emission of particulate matter, nitrogen oxides, and the carbon footprint of different shared AEVs in comparison with privately owned ICEVs. The approach shows that the system of a shared AEV fleet could lower externalities (accident avoidance, traffic jams, free spaces, parking costs and lifetime losses) in cities and generate cost benefits for customers.
This paper provides an analysis of the trend in autonomous driving traffic and the development of infrastructural support, whereas the requirements on the infrastructural support will be analyzed. Then selected traffic scenes will be implemented in an autonomous driving simulator tool in order to figure out the required parameters to assist the autonomous vehicle from the infrastructure.
Comparing multidimensional sensor data from vehicle fleets with methods of sequential data mining
(2020)
Optimized production strategy of the major capsid protein HPV 16L1 non-assembly variant in E. coli
(2020)
Waste
(2020)
For an efficient operation of a low voltage PMSM an optimized voltage usage is very important. Because of the relation between the low voltage and the high currents in this type of machine, a large voltage reserve is needed to compensate the influence of parameter mismatches and to guarantee a stable current control. As the power is limited by the low voltage in this type of hybrid drive systems, optimizing the voltage usage is also required to maximize the power and the torque availability. This paper describes a closed loop flux control to maximize the voltage usage. The controller feedback is used to estimate and maximize the available torque for each operating point.
In our present paper, we approach the mixed problem with initial and boundary conditions, in the context of thermoelasticity without energy dissipation of bodies with a dipolar structure. Our first result is a reciprocal relation for the mixed problem which is reformulated by including the initial data into the field equations. Then, we deduce a generalization of Gurtin’s variational principle, which covers our generalized theory for bodies with a dipolar structure. It is important to emphasize that both results are obtained in a very general context, namely that of anisotropic and inhomogeneous environments, having a center of symmetry at each point.
Due to the good mechanical properties, flax fiber-reinforced epoxy composites
are being widely used as a green alternative to glass fiber composites. However,
plant fibers absorb moisture from the environment, being in a higher moisture
uptake as the relative humidity (RH) increases. This absorbed moisture deteriorates the mechanical properties of the composites. In this study, geometric
and displacement potential function (DPF) approaches are used to predict the
mechanical properties of flax fiber-reinforced epoxy composites under environmental conditions, in particular, different RH values. The tensile properties
that were measured experimentally strongly agreed with the analytical findings.
Almost similar results were found for the tensile strain those were measured
experimentally and the one predicted by the geometric function.
However, the predicted strain values were 38% and 42% less than the experimental ones for 0% and 95% RH conditioned composites, respectively, when
DPF was used. Good conformity between the experimental, analytical, and
DPF formulation for predicting mechanical properties ensures the practical
applicability of this study. The formulations established in this work could,
therefore, be utilized to analytically solve laminated composites under specific
boundary conditions in structural applications.
The derivation and understanding of Partial Differential Equations relies heavily on the fundamental knowledge of the first years of scientific education, i.e., higher mathematics, physics, materials science, applied mechanics, design, and programming skills. Thus, it is a challenging topic for prospective engineers and scientists.
This volume provides a compact overview on the classical Partial Differential Equations of structural members in mechanics. It offers a formal way to uniformly describe these equations. All derivations follow a common approach: the three fundamental equations of continuum mechanics, i.e., the kinematics equation, the constitutive equation, and the equilibrium equation, are combined to construct the partial differential equations.
This book is the second edition of an introduction to modern computational mechanics based on the finite element method. It includes more details on the theory, more exercises, and more consistent notation; in addition, all pictures have been revised. Featuring more than 100 pages of new material, the new edition will help students succeed in mechanics courses by showing them how to apply the fundamental knowledge they gained in the first years of their engineering education to more advanced topics.
In order to deepen readers’ understanding of the equations and theories discussed, each chapter also includes supplementary problems. These problems start with fundamental knowledge questions on the theory presented in the respective chapter, followed by calculation problems. In total, over 80 such calculation problems are provided, along with brief solutions for each.
This book is especially designed to meet the needs of Australian students, reviewing the mathematics covered in their first two years at university. The 13-week course comprises three hours of lectures and two hours of tutorials per week.
Bone Cement
(2020)
This book provides an overview of the composition of polymeric and ceramic bone cements. It also discusses complex, biomimetic structures based on biomaterials, such as cells and bioactive molecules, which more closely resemble natural bone
The first chapter describes the main concepts of the cementation process and the parameters affecting it, while the second chapter focuses on the composition and structure of candidate biomaterials. Lastly, the third and fourth chapters present recent research aimed at improving the ability of naked biomaterials to enhance bone healing by adding cells and bioactive agents.
This study aid on numerical optimization techniques is intended for university undergraduate and postgraduate mechanical engineering students. Optimization procedures are becoming more and more important for lightweight design, where weight reduction can, for example in the case of automotive or aerospace industry, lead to lower fuel consumption and a corresponding reduction in operational costs as well as beneficial effects on the environment. Based on the free computer algebra system Maxima, the authors present procedures for numerically solving problems in engineering mathematics as well as applications taken from traditional courses on the strength of materials. The mechanical theories focus on the typical one-dimensional structural elements, i.e., springs, bars, and Euler–Bernoulli beams, in order to reduce the complexity of the numerical framework and limit the resulting design to a low number of variables. The use of a computer algebra system and the incorporated functions, e.g., for derivatives or equation solving, allows a greater focus on the methodology of the optimization methods and not on standard procedures.
The book also provides numerous examples, including some that can be solved using a graphical approach to help readers gain a better understanding of the computer implementation.
A Review on Dental Materials
(2020)
This book discusses the current biomaterials used for dental applications and the basic sciences underpinning their application. The most critical structures in the oral cavity are the teeth, which play a central role in speaking, biting, chewing, tasting and swallowing. Teeth consist of three types of tissue: the cementum, enamel and dentin, with bone and gingival tissue serving as supporting structures. Caries, tooth wear, trauma and mechanical defects can lead to severe facial conditions; however, correcting these defects remains a challenge for scientists and dentists. Presenting insights form a broad range of disciplines, including materials science, biology, physiology and clinical science, this book provides a timely review of the principles, processing and application of dental materials.
This Encyclopedia covers the entire science of continuum mechanics including the mechanics of materials and fluids. The encyclopedia comprises mathematical definitions for continuum mechanical modeling, fundamental physical concepts, mechanical modeling methodology, numerical approaches and many fundamental applications. The modelling and analytical techniques are powerful tools in mechanical civil and areospsace engineering, plus in related fields of plasticity, viscoelasticity and rheology. Tensor-based and reference-frame-independent, continuum mechanics has recently found applications in geophysics and materials.
This book offers an update on recent developments in modern engineering design. Different engineering disciplines, such as mechanical, materials, computer and process engineering, provide the foundation for the design and development of improved structures, materials and processes. The modern design cycle is characterized by the interaction between various disciplines and a strong shift to computer-based approaches where only a few experiments are conducted for verification purposes. A major driver for this development is the increased demand for cost reduction, which is also linked to environmental demands. In the transportation industry (e.g. automotive or aerospace), the demand for higher fuel efficiency is related to reduced operational costs and less environmental damage. One way to fulfil such requirements is lighter structures and/or improved processes for energy conversion. Another emerging area is the interaction of classical engineering with the health and medical sector.
This book provides an update on recent advances in various areas of modern engineering design, such as mechanical, materials, computer, and process engineering, which provide the foundation for the development of improved structures, materials, and processes. The modern design cycle is characterized by the interaction of different disciplines and a strong shift toward computer-based approaches involving only a small number of experiments for verification purposes. A major driver for this development is the increased demand for cost reduction, which is also connected to environmental demands. In the transportation industry (e.g. automotive or aerospace), where there is a demand for greater fuel efficiency, one solution is lighter structures and/or improved processes for energy conversion. Another emerging area is the interaction of classical engineering with the health and medical sector.
This book contains the selected and peer-reviewed manuscripts that were presented in the Conferences on Multidisciplinary Engineering and Technology (COMET 2019), held at the University Kuala Lumpur Malaysian Spanish Institute (UniKL MSI), Kedah, Malaysia from September 18 to 19, 2019. The aim of COMET 2019 was to present current and on-going research being carried out in the field of mechanical, manufacturing, electrical and electronics and general studies for engineering and technology. Besides, this book also contains the manuscripts from the System Engineering and Energy Laboratory (SEELAB) research cluster, UniKL which is actively doing research mainly focused on artificial intelligence, metal air batteries, advanced battery materials and energy material modelling fields. This volume is the third edition of the progress in engineering technology, Advanced Structured Materials which provides in-depth ongoing research activities among academia of UniKL MSI. Lastly, it is hoped to foster cooperation among organisations and research in the covered fields.
OAFuser: Online Adaptive Extended Object Tracking and Fusion using automotive Radar Detections
(2020)
This paper presents the Online Adaptive Fuser: OAFuser, a novel method for online adaptive estimation of motion and measurement uncertainties for efficient tracking and fusion by applying a system of several estimators for ongoing noise along with the conventional state and state covariance estimation. In our system, process and measurement noises are estimated with steady-state filters to obtain combined measurement noise and process noise estimators for all sensors in order to obtain state estimation with a linear Minimum Mean Square Error (MMSE) estimator and accelerating the system’s performance. The proposed adaptive tracking and fusion system was tested based on high fidelity simulation data and several real-world scenarios for automotive radar, where ground truth data is available for evaluation. We demonstrate the proposed method’s accuracy and efficiency in a challenging, highly dynamic scenario where our system is benchmarked with Multiple Model filter in terms of error statistics and run time performance.
In this chapter, to investigate the tensile behavior of CNTs, finite element models of single-walled carbon nanotubes (SWCNTs) in perfect and doped modes for common types of carbon nanotube (CNT) configuration, i.e., the armchair, zigzag, and chiral models, were generated using a commercial finite element software (MSC Marc). To create the computational models, nodes were placed at the locations of carbon atoms and the bonds between them were modeled using three-dimensional elastic generalized beam elements. Doped models were simulated by three different heteroatoms including silicon, nitrogen, and boron separately with the doping concentration ranging from 0 to 5%. Young’s moduli of all models were obtained and compared with the perfect structures. The results indicated that Young’s modulus of chiral SWCNTs is larger than the moduli of the armchair and zigzag SWCNTs in all models and incorporating the silicon and boron atoms into CNT led to a linear reduction in Young’s modulus which was most significant for silicon and less noticeable for boron. Regarding nitrogen doping, a different trend was observed that was a negligible and less conspicuous increment in the value of Young’s modulus by increasing the percentage of doping. Besides, this behavior was the same for all armchair, zigzag, and chiral configurations with the same dopant atom. The investigations also revealed that the structural irregularity and ripples, which are induced by dopant atoms, are a key factor which influences the tensile behavior of CNTs. Our results for Young’s modulus of doped CNTs are in good agreement with recent investigations.
This paper aims to analyze the stress and strain states appearing in the elbow of a tube, such as those commonly used in a city’s water supply network. The stress field is characterized by the fact that there is a significant stress increase when compared to a straight tube. As a result, the strength of such an elbow must be investigated and guaranteed for such a network to be well designed. A practical solution used is to anchor the elbow in a massive concrete block. The paper compares the stress field that occurs in the elbow when it is free, buried in the ground, and when it is anchored in a massive concrete block. Furthermore, we investigate how a crack appears and propagates in the elbow. This happens especially for the elbow buried in the ground where the stress and strain are higher than when the elbow is anchored in concrete. The results obtained can be used in the current practice in the case of water supply networks made by high-density polyethylene pipes.
Herein, the general constitutive equation of bi-phasic materials equipped with orientation tensor is presented in direct notation. The formulation is refined by some correction factors specific to natural fibre-reinforced composites; then, a planar case is derived. The necessity of local information is emphasised through the introduction of auxiliary maps, which included volume fraction and orientation data. A semi-analytical homogenisation method is introduced through finite element analysis. Auxiliary maps are shown to be a better alternative to the overall orientation of fibres. Global calculations are insensitive to local variations whilst appropriate auxiliary maps offer refined results. Considering the multidisciplinary application of orientation tensors, the proposed scheme can be used in all areas where local information cannot be disregarded.
Additive manufacturing offers unique possibilities to produce complex components, which would not be possible or only very difficult to be realizable with conventional manufacturing processes. The potential of additive manufacturing of aluminum alloys has already been realized in prototyping, but still offers potential in the establishment of series applications. For enabling the establishment of additive manufacturing in series applications, comprehensive knowledge about the material behavior is necessary. This study examines the torsional behavior of additive manufactured AlSi10Mg samples and shows the correlation between tensile and torsional strength. Comprehensive torsion tests with strain gauges were performed and significant directional dependencies were shown. The correlation factor in the area of torsional yield strength/tensile yield strength and torsional strength/tensile strength was determined and was compared with the yield/failure conditions according to Tresca and von Mises.
The moisture absorption behavior of flax fiber-reinforced epoxy composites is deliberated to be a serious issue. This property restricts their usage as outdoor engineering structures. Therefore, this study provides an investigation of moisture in flax fibers on the performance of the flax/epoxy composite materials based on their shear responses. The ±45° aligned flax fibers exposed to different relative humidities (RH) and the vacuum infusion process was used to manufacture the composite specimens. The optimum shear strength (40.25 ± 0.75 MPa) was found for the composites manufactured with 35% RH-conditioned flax fibers, but the shear modulus was reduced consistently with increasing RH values. Although shear strength was increased because of fiber swelling with increased moisture absorption rate until 35% RH environments with good microstructures, nonetheless, strength and modulus both started to decrease after this range. A very poor microstructure has been affirmed by the SEM images of the composite samples conditioned at 90% RH environments.
The aim of the current work was to illustrate the effect of the fibre area correction factor on the results of modelling natural fibre-reinforced composites. A mesoscopic approach is adopted to represent the stochastic heterogeneity of the composite, i.e. a meso-structural numerical model was prototyped using the finite element method including quasi-unidirectional discrete fibre elements embedded in a matrix. The model was verified by the experimental results from previous work on jute fibres but is extendable to every natural fibre with cross-sectional non-uniformity. A correction factor was suggested to fine-tune both the analytical and numerical models. Moreover, a model updating technique for considering the size-effect of fibres is introduced and its implementation was automated by means of FORTRAN subroutines and Python scripts. It was shown that correcting and updating the fibre strength is critical to obtain accurate macroscopic response of the composite when discrete modelling of fibres is intended. Based on the current study, it is found that consideration of the effect of flaws on the strength of natural fibres and inclusion of the fibre area correction factor are crucial to obtain realistic results.
Background:
Glaucoma, a characteristic type of optic nerve degeneration in the posterior pole of the eye, is a common cause of irreversible vision loss and the second leading cause of blindness worldwide. As an optic neuropathy, glaucoma is identified by increasing degeneration of retinal ganglion cells (RGCs), with consequential vision loss. Current treatments only postpone the development of retinal degeneration, and there are as yet no treatments available for this disability. Recent studies have shown that replacing lost or damaged RGCs with healthy RGCs or RGC precursors, supported by appropriately designed bio-material scaffolds, could facilitate the development and enhancement of connections to ganglion cells and optic nerve axons. The consequence may be an improved retinal regeneration. This technique could also offer the possibility for retinal regeneration in treating other forms of optic nerve ailments through RGC replacement.
Methods:
In this brief review, we describe the innovations and recent developments in retinal regenerative medicine such as retinal organoids and gene therapy which are specific to glaucoma treatment and focus on the selection of appropriate bio-engineering principles, biomaterials and cell therapies that are presently employed in this growing research area.
Results:
Identification of optimal sources of cells, improving cell survival, functional integration upon transplantation, and developing techniques to deliver cells into the retinal space without provoking immune responses are the main challenges in retinal cell replacement therapies.
Conclusion:
The restoration of visual function in glaucoma patients by the RGC replacement therapies requires appropriate protocols and biotechnology methods. Tissue-engineered scaffolds, the generation of retinal organoids, and gene therapy may help to overcome some of the challenges in the generation of clinically safe RGCs.
The methodology of the approximation and interpretation of thermal desorption spectra (TDS) of hydrogen in some carbon nanostructures and graphite has been developed and applied for such materials.
The methodology is based on a definite approximation by the symmetrical Gaussians of the hydrogen thermal desorption spectra, obtained by using one single heating rate, for carbon materials and nanomaterials, and a definite processing of the Gaussians, in the approximation of the first-order reactions and the second-order ones. It results in determining (with a satisfactory accuracy, for the further physical analysis), from TDS data of one single heating rate, the activation energies and pre-exponential factors of the rate constants of desorption processes corresponding to the main TDS peaks with different temperatures of the maximum desorption rate. The developed methodology contains several successive steps of its implementation, including the use of several “criterions of truth” and the final verification and/or modification of the results, with the help of numerical modeling methods. This technique is not less informative, but much less time-consuming in experimental terms compared to the generally accepted classical Kissinger method, which demands using of several heating rates, and has strict limits of applicability. Furthermore, the methodology allows one to reveal physics and atomic mechanisms of the main desorption processes through thermodynamic analysis of the obtained peak characteristics and comparison with the corresponding independent experimental and theoretical data.
The purpose of such a methodology is to further reveal the weakly studied physics of the main states of hydrogen in carbon materials and nanomaterials, and not the thorough detailed mathematical description of the spectra. For this case, both the large difference and the large spread of the known experimental and theoretical values of the thermodynamic characteristics of the main desorption processes, important for hydrogen storage problems, are also taken into account.
Hot isostatic pressing can be utilized to reduce the anisotropic mechanical properties of Al–Si–Mg alloys fabricated by laser powder-bed fusion (L-PBF). The implementation of post processing densification processes can open up new fields of application by meeting high quality requirements defined by aircraft and automotive industries. A gas pressure of 75 MPa during hot isostatic pressing lowers the critical cooling rate required to achieve a supersaturated solid solution. Direct aging uses this pressure related effect during heat treatment in modern hot isostatic presses, which offer advanced cooling capabilities, thereby avoiding the necessity of a separate solution annealing step for Al–Si–Mg cast alloys. Hot isostatic pressing, followed by rapid quenching, was applied to both sand cast as well as laser powder-bed fused Al–Si–Mg aluminum alloys. It was shown that the critical cooling rate required to achieve a supersaturated solid solution is significantly higher for additively manufactured, age-hardenable aluminum alloys than it is for comparable sand cast material. The application of hot isostatic pressing can be combined with heat treatment, consisting of solution annealing, quenching and direct aging, in order to achieve both a dense material with a small number of preferred locations for the initiation of fatigue cracks and a high material strength.
Our study is dedicated to a composite, which, in fact, is a mixture of two thermoelastic micropolar bodies. We formulate the mixed initial boundary value problem in this context and define the domain of influence for given data. For any solution of the mixed problem we associate a measure and prove a second-order differential inequality for it. Based on the maximum principle for the heat equation and on the second-order differential inequality, we establish an estimate which proves that the thermal and the mechanical effects, at large distance from the domain of influence, are dominated by an exponential decay.
Effect of voids in a heat-flux dependent theory for thermoelastic bodies with dipolar structure
(2020)
The objective of this study is to investigate the influence of veneering technique (hand-layering vs. milling) on the fracture resistance of bi-layer implant-supported zirconia-based hybrid-abutment crowns. Mandibular molar copings were anatomically designed and milled. Copings were then veneered by hand-layering (HL) (n = 20) and milling using the Cad-On technique (LD) (n = 20). Crowns were cemented to zirconia hybrid-abutments. Ten samples of each group acted as a control while the remaining ten samples were subjected to fatigue in a chewing simulator. Crowns were loaded between 50 and 100 N for 1.2 million cycles under simultaneous temperature fluctuation between 5 and 55 °C. Crowns were then subjected to static load a to fracture test. Data were statistically analysed using the one-way ANOVA. Randomly selected crowns from each group were observed under scanning electron microscopy to view fractured surfaces. Study results indicate that during fatigue, LD crowns had a 100% survival rate; while HL crowns had a 50% failure rate. Fracture resistance of LD crowns was statistically significantly higher than that of HL crowns at the baseline and after fatigue (p ≤ 0.05). However, fatigue did not cause a statistically significant reduction in fracture resistance in both LD and HL groups (p > 0.05). Copings fractured in the LD crowns only and the fracture path was different in both LD and HL groups. According to the results, it was concluded that milled veneer implant-supported hybrid-abutment crowns exhibit significantly higher fracture resistance, and better withstand clinical masticatory loads in the posterior region compared to the hand-layered technique. Also, fatigue application and artificial aging caused no significant strength reduction in both techniques. Clinical significance: Different veneering techniques and materials (hand-layering or milling) act differently to clinical forces and environment and may be prone to early chipping during service. Therefore, practitioners are urged to consider the appropriate veneering protocol for posterior implant-supported hybrid-abutment restorations.
We consider the mixed initial-boundary value problem in the context of the
Moore-Gibson-Thompson theory of thermoelasticity for dipolar bodies. We consider the case of heat conduction with dissipation. Even if the elasticity tensors
are not supposed to be positively defined, we have proven both, the uniqueness
and the instability of the solution of the mixed problem. In the case that the mass
density and the thermal conductivity tensor are positive, we obtain the uniqueness
of the solution using some Lagrange type identities.
In our study, we consider the linear mixed initial boundary value problem for a porous elastic body having a dipolar structure. The equations that describe the elastic dipolar deformations are coupled with the equations which describe the evolution of the voids by means of certain coefficients. Our main result proves the continuous dependence of solutions for the mixed problem with regard to the coefficients which perform this coupling. Using an adequate measure, we can evaluate the continuous dependence by means of some estimate regarding the gradient of deformations and the gradient of the function that describes the evolution of the voids.
This study is concerned with the linear elasticity theory for bodies with a dipolar structure. In this context, we approach transient elastic processes and the steady state in a cylinder consisting of such kind of body which is only subjected to some boundary restrictions at a plane end. We will show that at a certain distance d=d(t), which can be calculated, from the loaded plan, the deformation of the body vanishes. For the points of the cylinder located at a distance less than d, we will use an appropriate measure to assess the decreasing of the deformation relative to the distance from the loaded plane end. The fact that the measure, that assess the deformation, decays with respect to the distance at the loaded end is the essence of the principle of Saint-Venant.
Laser powder-bed fusion (LPBF) has significantly gained in importance and has become one of the major fabrication techniques within metal additive manufacturing. The fast cooling rates achieved in LPBF due to a relatively small melt pool on a much larger component or substrate, acting as heat sink, result in fine-grained microstructures and high oversaturation of alloying elements in the α-aluminum. Al-Si-Mg alloys thus can be effectively precipitation hardened. Moreover, the solidified material undergoes an intrinsic heat treatment, whilst the layers above are irradiated and the elevated temperature in the built chamber starts the clustering process of alloying elements directly after a scan track is fabricated. These silicon-magnesium clusters were observed with atom probe tomography in as-built samples. Similar beneficial clustering behavior at higher temperatures is known from the direct-aging approach in cast samples, whereby the artificial aging is performed immediately after solution annealing and quenching. Transferring this approach to LPBF samples as a possible post-heat treatment revealed that even after direct aging, the outstanding hardness of the as-built condition could, at best, be met, but for most instances it was significantly lower. Our investigations showed that LPBF Al-Si-Mg exhibited a high dependency on the quenching rate, which is significantly more pronounced than in cast reference samples, requiring two to three times higher quenching rate after solution annealing to yield similar hardness results. This suggests that due to the finer microstructure and the shorter diffusion path in Al-Si-Mg fabricated by LPBF, it is more challenging to achieve a metastable oversaturation necessary for precipitation hardening. This may be especially problematic in larger components.
Das Interesse der Industrie an additiv gefertigten Bauteilen steigt z unehmend, wobei mit zunehmendem Verständnis der statischen Kennwerte nunmehr der Fokus in Richtung der dynamischen Festigkeiten wandert. Deswegen werden Einflussparameter auf die Lebensdauer und potenzielle Nachbearbeitungsmethoden untersucht und analysiert. Ein großer Einfluss ist dabei der Oberflächengüte und den durch Rautiefen initiierten Kerbeffekten zuzuschreiben. Deswegen werden unterschiedliche Methoden zur Verbesserung der Oberflächengüte untersucht. Dabei werden die Verfahren Laserpolieren, elektrochemisches Polieren und Hartmetallkugelstrahlen und deren Auswirkung auf Oberflächengüte sowie Härte untersucht. Für das elektrochemische Polieren werden die Proben in einer Perchlorsäure für 90 s bei 32 V und maximal 10 A poliert. Das Hartmetallkugelstrahlen wird mit einem UFS 100 Strahlmittel bei einem Druck von 4 bar und einer Strahldauer von 10 s ausgeführt. Anschließend werden Wöhlerlinien für die unterschiedlichen Zustände mittels Umlaufbiegeversuch ermittelt, welche mit Referenzwerten analysierter konventioneller Proben verglichen werden. Des Weiteren werden die Bruchflächen analysiert. Die Untersuchungen ergaben ein hohes Optimierungspotenzial der additiv gefertigten Proben bei einer Verdichtung der Oberfläche sowie einer Entfernung der Randschicht durch eine spanende Bearbeitung. Dadurch wurden höhere Zeitfestigkeiten als mit konventionell gefertigten Proben erreicht.
Development of environment-friendly natural fiber composites has been a recent trend. However, due to the fact that natural fibers permit high level of moisture absorption from the surroundings, it can lead to weak bindings and degradation of composite properties. This paper presents an experimental study on the dynamic performance of flax fiber composite beams manufactured at different relative humidity (RH) levels. Five types of flax fiber-reinforced composite materials were made under different RH values, i.e., dry, 35%, 50%, 70%, and 95% RH, and beam samples were prepared using the composite. Impact hammer testing was conducted to measure the natural frequencies and damping of the beams. It was found that for the first three modes, while the resonant frequencies are very close for most samples, there is a clear drop of frequencies for the composite fabricated at 95% RH. Along with an increase of the RH level, the damping ratios for all the three modes have reported a slight increase, but the variation is not significant.
The characteristics and atomic mechanisms (physics) of processes of thermal desorption of deuterium from isotropic graphite at temperatures 700–1700 K are considered.
Metal additive manufacturing of dental prostheses consisting of cobalt−chromium−tungsten (Co−Cr−W) alloys poses an alternative to investment casting. However, metal additive manufacturing processes like Laser Powder‐Bed Fusion (LPBF) can impact the elastic constants and the mechanical anisotropy of the resulting material. To investigate the phase compositions of mechanically different specimens in dependence of their postprocessing steps (e. g. heat treatment to relieve stress), the current study uses X‐ray Diffraction (XRD), Electron BackScatter Diffraction (EBSD), and Transmission Electron Microscopy (TEM) for phase identification. Our studies connect plastic deformation of Remanium star CL alloy with the formation of the hexagonal ϵ‐phase and heat treatment with the formation of the D024‐phase, while partially explaining previously observed differences in Young's moduli.
Laser powder bed fusion has become one of the major techniques within metal additive manufacturing, especially when delicate structures and high geometric accuracy are concerned. Lately, the awareness of the material-specific macroscopic anisotropy has risen and led to widespread investigations on the static mechanical strength. However, little is known about the fracture behavior of the layer-wise fabricated metal components and their affinity of crack propagation between consecutive layers, which is particularly important for aluminium–silicon alloys containing embrittled zones in double-irradiated areas. A recent study indicated that there is a significant drop in fracture toughness in case the crack growth direction is parallel to the layering. To investigate this matter further and to shed light on the fracture toughness behavior in the range of a 0°–45° angle offset between the crack growth direction relative to the layering, notched samples with varying polar angles were subjected to mode I fracture toughness testing. Our results indicate that the fracture toughness is an almost-stable characteristic up to a mismatch of about 20° between the crack propagation path and the layering, at which point the fracture toughness decreases by up to 10%.
Laser powder-bed fusion has become one of the most important techniques in additive manufacturing. For guaranteeing the possibility of manufacturing highly specialized and advanced components, currently intensive research is carried out in this field. One area of this research is the material-specific macroscopic anisotropy, which is investigated in our work by comprehensive static mechanical experiments. The material which was tested within this study was the precipitation-hardenable AlSi10Mg alloy, with the focus on installation space orientation. Tensile and compression tests were performed, the results for the Young's modulus in compressive loading exceeded the previously known values of this material in tensile loading and achieved values of up to 79.8 GPa. As a result of this investigation, a chemical spectroscopic analysis was undertaken and from the actual chemical composition, a relative density of 99.86% of the samples was determined.
A number of planetary boundaries, including climate change as a result of greenhouse gas emissions, has already been exceeded. This situation has deleterious consequences for public health. Paradoxically, 4.4% of these emissions are attributable to the healthcare sector. These problems have not been sufficiently acknowledged in health professions curricula. This paper addresses two main issues, humanistic learning and the application of knowledge acquisition to clinical practice. Humanistic learning principles can be used to emphasize learner-centered approaches, including knowledge acquisition and reflection to increase self-awareness. Applying humanistic principles in everyday life and clinical practice can encourage stewardship, assisting students to become agents for change. In terms of knowledge and skills application to clinical practice, an overview of varied and novel approaches of how sustainable education can be integrated at different stages of training across several health care professions is provided. The Health and Environment Adaptive Response Taskforce (HEART) platform as an example of creating empowered learners, the NurSusTOOLKIT, a multi-disciplinary collaboration offering free adaptable educational resources for educators and the Greener Anaesthesia and Sustainability Project (GASP), an example of bridging the transition to clinical practice, are described.
Application and machine learning methods for dynamic load point controls of electric vehicles (xEVs)
(2020)
From the customer's perspective, the appeal of electric vehicles depends on the simplicity and ease of their use, such as flexible access to electric power from the grid to recharge the batteries of their vehicles. Therefore, the expansion of charging infrastructure will be an important part of electric mobility. The related charging infrastructure is a big challenge for the load capacity of the grid connection without additional intelligent charge management: if the control of the charging process is not implemented, it is necessary to ensure the total of the maximum output of all xEVs at the grid connection point, which requires huge costs. This paper proposes to build a prediction module for forecasting dynamic charging load using machine learning (ML) techniques. The module will be integrated into a real charge management concept with optimization procedures for controlling the dynamic load point. The value of load forecasting through practical load data of a car park were taken to illustrate the proposed methods. The prediction performance of different ML methods under the same data condition (e.g., holiday data) are compared and evaluated.
Negotiations are a relevant and highly complex business skill. Therefore, extensive training is required to become a good negotiator. Such training is offered by universities for their students and by companies for their employees. The present paper designs gamified feedback features in electronic negotiation training and evaluates their potential and their effects. Following a design science research method, feedback mechanisms in electronic negotiation training are derived from literature. An assessment regarding their relevance for e-negotiation training shows a preparation quiz, set and track goals and expert reviews to be the most useful gamified feedback mechanisms. Dedicated mock-ups implementing these feedback mechanisms are designed and evaluated in semi-structured interviews showing their capability to improve relevant negotiation skills, as well as motivation and competence of the learners. Out of the three mock-ups, the interviewees prefer the feedback mechanisms “expert review” and “set and track goals”; both mechanisms provide a competence-confirming learning experience and an autonomous learning experience.
Interpretable neural networks based on continuous-valued logic and multicriteria decision operators
(2020)
Recently the production of electric cars is increasing worldwide. The main target is to lower the greenhouse gas emissions. Even if an electrified vehicle is locally emission-free the manufacturing of lithium ion batteries are producing significant amounts of CO2. In order to decrease the air pollution governments are considering recycling programs to extend battery life and usage of important raw materials. A new approach to recover LiNixMnyCozO2 (NMC) particles while saving the chemical and morphological properties using water was presented by Tim Sieber et al. [1]. With the presented study, we are focusing on the analysis of the effects on the Global Warming Potential (GWP) for the water based recycling process based on a reuse of NMC material in new batteries.
It is possible to reduce the ecological damage of the manufacturing process of Li-Ion battery cells even with little amounts of recovered cathode material that is used for the production of new battery cells. Based on the suggestion that 95% of the NMC cathode material can be recovered by the hydrometallurgical recovery and the reuse of 10% within the production of new batteries a reduction of the GWP by 7% ,can be identified for the cathode materials. For other impact categories such as Acidification Potential (AP), Eutrophication Potential (EP), and Photochemical Ozone Creation Potential (POCP), savings of 10%, 11%, and 8 % can be achieved respectively.
The studied water based recycling process can be quoted as environment-friendly and leads to a reduction of all impact categories by a re-use of 10% recovered NMC material. Based on this knowledge an additional recycling on substance level is recommended.
This document defines three YANG 1.1 [RFC7950] modules to support the configuration of TCP clients and TCP servers, either as standalone or in conjunction with a stack protocol layer specific configuration.
TCP Usage Guidance in the Internet of Things (IoT), draft-ietf-lwig-tcp-constrained-node-networks-13
(2020)
This document provides guidance on how to implement and use the Transmission Control Protocol (TCP) in Constrained-Node Networks(CNNs), which are a characteristic of the Internet of Things (IoT).Such environments require a lightweight TCP implementation and may not make use of optional functionality. This document explains a number of known and deployed techniques to simplify a TCP stack as well as corresponding tradeoffs. The objective is to help embedded
developers with decisions on which TCP features to use.
This document specifies a YANG model for TCP on devices that are configured by network management protocols. The YANG model defines a container for all TCP connections and groupings of some of the parameters that can be imported and used in TCP implementations or by other models that need to configure TCP parameters. The model includes definitions from YANG Groupings for TCP Client and TCP Servers (I-D.ietf-netconf-tcp-client-server). The model is NMDA (RFC
8342) compliant.