Objective Little is known about the association between whole-blood nicotinamide adenine dinucleotide(NAD^(+))levels and nabothian cysts.This study aimed to assess the association between NAD^(+)levels and nabothian c...Objective Little is known about the association between whole-blood nicotinamide adenine dinucleotide(NAD^(+))levels and nabothian cysts.This study aimed to assess the association between NAD^(+)levels and nabothian cysts in healthy Chinese women.Methods Multivariate logistic regression analysis was performed to analyze the association between NAD^(+)levels and nabothian cysts.Results The mean age was 43.0±11.5 years,and the mean level of NAD^(+)was 31.3±5.3μmol/L.Nabothian cysts occurred in 184(27.7%)participants,with single and multiple cysts in 100(15.0%)and84(12.6%)participants,respectively.The total nabothian cyst prevalence gradually decreased from37.4%to 21.6%from Q1 to Q4 of NAD^(+)and the prevalence of single and multiple nabothian cysts also decreased across the NAD^(+)quartiles.As compared with the highest NAD^(+)quartile(≥34.4μmol/L),the adjusted odds ratios with 95%confidence interval of the NAD^(+)Q1 was 1.89(1.14–3.14)for total nabothian cysts.The risk of total and single nabothian cysts linearly decreased with increasing NAD^(+)levels,while the risk of multiple nabothian cysts decreased more rapidly at NAD^(+)levels of 28.0 to35.0μmol/L.Conclusion:Low NAD^(+)levels were associated with an increased risk of total and multiple nabothian cysts.展开更多
This article is about illustrating a workflow for incorporating reliability measures to typical electric machine design optimization scenarios.Such measures facilitate comparing designs not only for rated conditions,b...This article is about illustrating a workflow for incorporating reliability measures to typical electric machine design optimization scenarios.Such measures facilitate comparing designs not only for rated conditions,but also allow to analyze their performance in the presence of unevitable tolerances.Consequently,by additionally considering reliability or robustness as objectives compared to conventional optimization scenarios,designs featuring low parameter sensitiveness can be obtained.The analysis of the design’s reliability as part of solving optimization problems involves a significant increase in required numerical evaluations.To minimize the associated prolongation of the runtime,an approach featuring a design of experiments based reduction of required computations and a consequent surrogate modeling technique is presented here.After successful training,the metamodel can be applied for fast evaluating lots of different parameter combinations.A test problem is defined and analyzed.Based on the observed findings,the necessity of incorporating robustness evaluations to machine design optimization becomes evident.In addition,the derived models allow for studying the impact of any tolerance-affected parameter on the machine performance in detail.This facilitates further beneficial studies,as for instance the analysis of selected changes of tolerance levels rather than a general minimization of the respective ranges which usually is associated with high production cost.展开更多
The interplay of magnetic and semiconducting properties has been in the focus for more than a half of the century. In this introductory article we briefly review the key properties and functionalities of various magne...The interplay of magnetic and semiconducting properties has been in the focus for more than a half of the century. In this introductory article we briefly review the key properties and functionalities of various magnetic semiconductor families, including europium chalcogenides, chromium spinels, dilute magnetic semiconductors, dilute ferromagnetic semiconductors and insulators, mentioning also sources of non-uniformities in the magnetization distribution, accounting for an apparent high Curie temperature ferromagnetism in many systems. Our survey is carried out from today's perspective of ferromagnetic and antiferromagnetic spintronics as well as of the emerging fields of magnetic topological materials and atomically thin 2D layers.展开更多
Three recent breakthroughs due to AI in arts and science serve as motivation:An award winning digital image,protein folding,fast matrix multiplication.Many recent developments in artificial neural networks,particularl...Three recent breakthroughs due to AI in arts and science serve as motivation:An award winning digital image,protein folding,fast matrix multiplication.Many recent developments in artificial neural networks,particularly deep learning(DL),applied and relevant to computational mechanics(solid,fluids,finite-element technology)are reviewed in detail.Both hybrid and pure machine learning(ML)methods are discussed.Hybrid methods combine traditional PDE discretizations with ML methods either(1)to help model complex nonlinear constitutive relations,(2)to nonlinearly reduce the model order for efficient simulation(turbulence),or(3)to accelerate the simulation by predicting certain components in the traditional integration methods.Here,methods(1)and(2)relied on Long-Short-Term Memory(LSTM)architecture,with method(3)relying on convolutional neural networks.Pure ML methods to solve(nonlinear)PDEs are represented by Physics-Informed Neural network(PINN)methods,which could be combined with attention mechanism to address discontinuous solutions.Both LSTM and attention architectures,together with modern and generalized classic optimizers to include stochasticity for DL networks,are extensively reviewed.Kernel machines,including Gaussian processes,are provided to sufficient depth for more advanced works such as shallow networks with infinite width.Not only addressing experts,readers are assumed familiar with computational mechanics,but not with DL,whose concepts and applications are built up from the basics,aiming at bringing first-time learners quickly to the forefront of research.History and limitations of AI are recounted and discussed,with particular attention at pointing out misstatements or misconceptions of the classics,even in well-known references.Positioning and pointing control of a large-deformable beam is given as an example.展开更多
In the current study poly(lactic acid)PLA composites with a 3 wt%and 5 wt%of nanofibrillated cellulose(NFC)were produced by 3D-printing method.An enzymatic pretreatment coupled with mechanical fibrillation in a twin s...In the current study poly(lactic acid)PLA composites with a 3 wt%and 5 wt%of nanofibrillated cellulose(NFC)were produced by 3D-printing method.An enzymatic pretreatment coupled with mechanical fibrillation in a twin screw extruder was used to produce high consistency NFC.Scanning electron microscopy(SEM)equipped with Fibermetric software,FASEP fiber length distribution analysis,Furrier transform infrared spectroscopy(FT-IR),thermogravimetric analysis(TGA),tensile tests,impact tests and differential scanning calorimetry were used to characterize NFC and PLA/NFC composites.The results of the fiber length and width measurements together with the results of the SEM analysis showed that enzymatic hydrolysis coupled with a twin screw extrusion could effectively reduce the diameter and length of cellulose fibers.The produced NFC consisted of microand nanosized fibers entangled in a characteristic 3D-network.Based on the FT-IR analysis,no new bonds were formed during the enzymatic hydrolysis or fibrillation process.The TGA analysis confirmed that produced NFC can be used in hightemperature extrusion processing without NFC degradation.During the PLA/NFC composites preparation the NFC agglomerates were formed,which negatively influenced PLA/NFC composites impact properties.The slightly improved tensile strength and elastic modulus were reported for all composites when compared to the neat PLA.The elongation at break was not affected by the NFC addition.No significant differences in thermal stability were detectable among composites nor in comparation with the neat PLA.However,the crystallinity degree of the composite containing 5 wt%NFC was increased in respect to the neat PLA.展开更多
This work is about analyzing surface mounted permanent magnet machines regarding their sensitiveness related to erroneous magnet positioning.A finite element analysis based approach is presented and different topologi...This work is about analyzing surface mounted permanent magnet machines regarding their sensitiveness related to erroneous magnet positioning.A finite element analysis based approach is presented and different topologies in terms of slot and pole count are compared.The study further includes the analysis of multiple magnet widths and stator teeth widths.By contrast to most of previous studies,the work is based on evaluating the cumulative distribution function of the cogging torque in case of non-idealities.A Monte Carlo importance sampling based strategy is focused.This approach facilitates studying arbitrary tolerance distributions.Results reveal that topologies with particularly promising rated cogging torque behaviour exhibit the most significant performance degradation in presence of tolerances.A linear relationship is identified for cogging torque performance as function of the accuracy in magnet positioning.Results emphasize the necessity of tolerance analyses for electric machine design to not overrate their performance in the presence of manufacturing uncertainties.展开更多
The intensive research performed in the field of conjugated polymers during the last four decades gave rise to a new class of materials, in which the electrical conductivity can be adjusted to cover the entire range f...The intensive research performed in the field of conjugated polymers during the last four decades gave rise to a new class of materials, in which the electrical conductivity can be adjusted to cover the entire range from pure insulator to metallic [1]. Their ease of processability, low weight, mechanical flexibility and potential low production cost triggered the use of these "plastic semiconductors" for electronic device applications. Nowadays, organic light emitting diodes (OLED) [2] based on conjugated polymers are entering the market and organic field effect transistors (OFET) [3] are considered for replacing a:Si thin film transistors (TFT).展开更多
Modern computer techniques have been in use for several years to generate three-dimensional visualizations of human anatomy. Very good 3-D computer models of the human body are now available and used routinely in anat...Modern computer techniques have been in use for several years to generate three-dimensional visualizations of human anatomy. Very good 3-D computer models of the human body are now available and used routinely in anatomy instruction. These techniques are subsumed under the heading “virtual anatomy” to distinguish them from the conventional study of anatomy entailing cadavers and anatomy textbooks. Moreover, other imaging procedures (X-ray, angiography, CT and MR) are also used in virtual anatomy instruction. A recently introduced three-dimensional post-processing technique named Cinematic Rendering now makes it possible to use the output of routine CT and MR examinations as the basis for highly photo-realistic 3-D depictions of human anatomy. We have installed Cinematic Rendering (enabled for stereoscopy) in a high-definition 8K 3-D projection space that accommodates an audience of 150. The space’s projection surface measures 16 × 9 meters;images can be projected on both the front wall and the floor. A game controller can be used to operate Cinematic Rendering software so that it can generate interactive real-time depictions of human anatomy on the basis of CT and MR data sets. This prototype installation was implemented without technical problems;in day-to-day, real-world use over a period of 22 months, there were no impairments of service due to software crashes or other technical problems. We are already employing this installation routinely for educational offerings open to the public, courses for students in the health professions, and (continuing) professional education units for medical interns, residents and specialists—in, so to speak, the dissecting theater of the future.展开更多
Since the 1980s, various techniques have been used in the field of medicine for the post-processing of medical imaging data from computed tomography (CT) and magnetic resonance (MR). They include multiplanar reformati...Since the 1980s, various techniques have been used in the field of medicine for the post-processing of medical imaging data from computed tomography (CT) and magnetic resonance (MR). They include multiplanar reformations (MPR), maximum intensity projection (MIP) and Volume Rendering (VR). This paper presents the prototype of a new means of post-processing radiological examinations such as CT and MR, a technique that, for the first time, provides photorealistic visualizations of the human body. This new procedure was inspired by the quality of images achieved by animation software such as programs used in the entertainment industry, particularly to produce animated films. Thus, the name: Cinematic Rendering. It is already foreseeable that this new method of depiction will quickly be incorporated into the set of instruments employed in socalled virtual anatomy (teaching anatomy through the use of radiological depictions of the human body via X-ray, CT and MR in addition to the use of computer animation programs designed especially for human anatomy). Its potential for medical applications will have to be evaluated by future scientific investigations.展开更多
A 7-year-old boy presented with cerebellar ataxia with reduced tonicity, deficits of the fine and gross motor coordination skills and vestibular stimulus processing, as well as significantly delayed language developme...A 7-year-old boy presented with cerebellar ataxia with reduced tonicity, deficits of the fine and gross motor coordination skills and vestibular stimulus processing, as well as significantly delayed language development. MR imaging showed the so-called “molar tooth sign”, which was highly pathognomonic for the Joubert-Syndrome—an inherited cerebellar ataxia with a variety of clinical symptoms—and related entities. It is caused by a complex malformation of the cerebellar vermis and the midbrain. The cerebellar vermis is hypoplastic or completely absent;at the same time, the superior cerebellar peduncles are thickened. There is a lack of normal decussation of the fiber tracts in mesencephalon, which follow an abnormal horizontal course, as well as a lack of the decussation of the corticospinal fiber tracts in the caudal medulla oblongata and deformity of the 4th ventricle. Clinically, the triad of cerebellar ataxia, developmental retardation, and abnormal eye movements is indicating a related syndrome of this spectrum. The appearance of the involved children is characterized by dysmorphic facial features with epicanthus, broad nose bridge, low set ears and typically triangularly shaped and opened mouth. The diagnosis is usually made by imaging and clinical findings. Recently, advantages were made in genetic research on the Joubert syndrome and interesting findings published about diffusion tensor imaging and tractography. However, standard MR imaging, applying an adequate imaging protocol including sequences with excellent T1 contrast and 3D imaging with isotropic spatial resolution allowing reconstructions in all orientations, remains an essential tool for making this diagnosis.展开更多
This paper addresses the application of the continuum mechanics-based multiplicative decomposition for thermohyperelastic materials by Lu and Pister to Reissner’s structural mechanics-based,geometrically exact theory...This paper addresses the application of the continuum mechanics-based multiplicative decomposition for thermohyperelastic materials by Lu and Pister to Reissner’s structural mechanics-based,geometrically exact theory for finite strain plane deformations of beams,which represents a geometrically consistent non-linear extension of the linear shear-deformable Timoshenko beam theory.First,the Lu-Pister multiplicative decomposition of the displacement gradient tensor is reviewed in a three-dimensional setting,and the importance of its main consequence is emphasized,i.e.,the fact that isothermal experiments conducted over a range of constant reference temperatures are sufficient to identify constitutive material parameters in the stress-strain relations.We address various isothermal stress-strain relations for isotropic hyperelastic materials and their extensions to thermoelasticity.In particular,a model belonging to what is referred to as Simo-Pister class of material laws is used as an example to demonstrate the proposed procedure to extend isothermal stress-strain relations for isotropic hyperelastic materials to thermoelasticity.A certain drawback of Reissner’s structural-mechanics based theory in its original form is that constitutive relations are to be stipulated at the one-dimensional level,between stress resultants and generalized strains,so that the standardized small-scale material testing at the stress-strain level is not at disposal.In order to overcome this,we use a stress-strain based extension of the Reissner theory proposed by Gerstmayr and Irschik for the isothermal case,which we utilize here in the framework of the considered thermoelastic extension of the Simo-Pister stressstrain law.Consistent with the latter extension,we derive non-linear thermo-hyperelastic constitutive relations between stress-resultants and general strains.Special emphasis is given to linearizations and their consequences.A numerical example demonstrates the efficacy of the structural-mechanics approach in large-deformation problems.展开更多
Spinal dural arteriovenous fistulas (SDAVF) account for about 70% of all spinal AV shunts. We re-port on a 56-year-old male patient with progressive neurological symptoms. Pre- and post-contrast MR imaging of the spin...Spinal dural arteriovenous fistulas (SDAVF) account for about 70% of all spinal AV shunts. We re-port on a 56-year-old male patient with progressive neurological symptoms. Pre- and post-contrast MR imaging of the spine, including contrast-enhanced MR angiography was done on a 1.5 T MR scanner. In addition a special (pre-contrast) 3D turbo-spin-echo sequence with variable flip angle evolution (SPACE) was performed providing a slice thickness of 0.9 mm. T2-weighted images showed extensive widened and tortuous vascular structures with typical flow voids intradurally due to dilated pial veins. The origin of the spinal dural arteriovenous fistula was found to be the radiculomeningeal artery at level D10/11 on the left side, visualized by the T2-weighted 3D SPACE sequence and CE MRA. After imaging the patient was referred to an interventional neuroradiology department for therapy. With the detailed information from MR imaging concerning the fistula level the interventional radiologist was able to find the fistula immediately and consequently treated it successfully by endovascular therapy. Interpreting the MR images of this obvious case of a SDAVF, SPACE sequence after post processing with 3D MPR software directly led to the location of the AV shunt at D10/11 on the left side, better than 3D contrast-enhanced MR angiography did. Therefore, SPACE can be a useful adjunct in further evaluation of spinal dural arteriovenous fistula and especially in defining fistula level.展开更多
A significant impact of this work on the use of polymers is expected because the developed organo-nano particles (ONP) mixed into standard polymers will make them unique and traceable. The doping of polymers with non ...A significant impact of this work on the use of polymers is expected because the developed organo-nano particles (ONP) mixed into standard polymers will make them unique and traceable. The doping of polymers with non migrating ONP was demonstrated and applications for the recycling of plastics were discussed. Thus, perylene derivatives were linked to polymerisable vinyl groups and copolymerized under RAFT conditions (Reversible Addition Fragmentation chain Transfer) with styrene and methylmethacrylate, respectively, to obtain fluorescent ONP with sizes of 40 nm or even less and narrow distributions of molecular weight in most cases with polydispersities PD of 1.1 and lower.展开更多
The paper focuses on links between the EU ETS (European Union Emissions Trading Scheme) and selected (domestic) greenhouse gas ETS (emissions trading schemes) from Asia and North America which could open up a pe...The paper focuses on links between the EU ETS (European Union Emissions Trading Scheme) and selected (domestic) greenhouse gas ETS (emissions trading schemes) from Asia and North America which could open up a perspective to keep the idea of emissions trading alive on a global scale and confront the actual uncertainty in future climate policy. The approach consists of investigating qualitatively the essential requirements of this alternative bottom-up approach. It is evaluated if variations or inconsistencies in the structure and design of domestic ETS as well as legal and institutional characteristics harm or facilitate the concept of linking with the EU ETS. The evaluation of systems leads to the exclusion of systems with voluntary character, relative caps, unrestricted borrowing and price caps from the group of potential linking candidates.展开更多
This article is about a comparison of different measures for determining the robustness or reliability of electric machine designs in the presence of inevitable tolerances.The selected criteria shall be suitable for c...This article is about a comparison of different measures for determining the robustness or reliability of electric machine designs in the presence of inevitable tolerances.The selected criteria shall be suitable for concurrent evaluation in the course of solving state-of-the-art large scale multi-objective opti-mization problems.In the past,besides particularly customized criteria,mainly gradient based measures,worst case information,or standard deviation based quantities were considered.In this work,the quantile measure is introduced for electric machine design optimization and compared with the existing solutions.The evaluation of a design’s robustness is typically examined based on finite element simulations.As for most measures a signif-icant number of parameter combinations and thus computations are required,a surrogate model assisted approach is presented to minimize computational effort and runtime.A test problem is defined and analyzed to illustrate the differences of selected robustness measures.Results reveal the importance of considering robustness in the optimization process.Moreover,a careful choice of appropriate measures has to be taken.Selected designs are compared and conclusions and an outlook on future activities are presented.展开更多
This paper explores how empirical capability approach studies assess well-being for young and old generations in affluent countries, defined as high-income OECD countries. After a brief overview on the theoretical cap...This paper explores how empirical capability approach studies assess well-being for young and old generations in affluent countries, defined as high-income OECD countries. After a brief overview on the theoretical capability background and empirical core decisons, the authors discuss empirical capability studies on the well-being of children, adolescents and the elderly. The authors find that the issues of child and youth well-being have been increasing interested by capability researchers while despite of the importance of demographic change, few researchers deal with old-age issues. The authors conclude that for young as well as old generations, capability approach studies confirm that income assessment is not sufficient to capture well-being for the young and the old but has to be enriched by a more comprehensive perspective on capabilities and functionings. Moreover, it is recommendable and issues that have already entered the agenda of studies on for research on elderly to adopt research methods, questions capabilities of children and young adults. As capability sets for both, young and old generations are in general characterized by changes, i.e., expansions in the case of children, declines in the case of older people, both may benefit from a more dynamic perspective on life cycles on their way to potential dynamic capability theories and empirics.展开更多
Composites based on melamine formaldehyde resins filled with exfoliated graphite or so called nanographite have been prepared to achieve electrical conductivity and improve mechanical strength and thermal stability. T...Composites based on melamine formaldehyde resins filled with exfoliated graphite or so called nanographite have been prepared to achieve electrical conductivity and improve mechanical strength and thermal stability. The nanographite was synthesized by thermal treatment of oxidized graphite and the incorporation into the melamine matrix was accomplished during the melamine formaldehyde reaction. A homogenous dispersion of the filler in the matrix and the forming of a connecting network based on graphite sheets were proved by SEM images. The graphite filler was able to increase the flexural strength of molded testing specimens compared to unfilled resins and electrical conductivity was achieved starting at 2 wt% nanographite.展开更多
Carbon fibers composites are well</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">known as high tech materials but are also recognized as...Carbon fibers composites are well</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">known as high tech materials but are also recognized as a problem after use as they have to be deposited in landfills. Pyrolysis is an attractive process for recycling carbon fibers from used composites as well as offcuts from prepregs. Pyrolysis of carbon fiber composite prepregs is carried out in a pilot plant with a single screw reactor. The pyrolysis products, carbon fibers and pyrolysis vapor are fully characterized. Variation of pyrolysis temperature is carried out to obtain carbon fibers with the best possible surface properties. In order to compare the mechanical properties of the recycled carbon fibers with virgin material, composite materials with polyamide are produced and their properties compared.展开更多
基金supported by grants from the NSFC-Regional Innovation and Development Joint Fund(No.U22A20364)the National Key R&D Program of China(No.2021YFC2500500)the National Natural Science Foundation of China(No.81973112,No.92049302)。
文摘Objective Little is known about the association between whole-blood nicotinamide adenine dinucleotide(NAD^(+))levels and nabothian cysts.This study aimed to assess the association between NAD^(+)levels and nabothian cysts in healthy Chinese women.Methods Multivariate logistic regression analysis was performed to analyze the association between NAD^(+)levels and nabothian cysts.Results The mean age was 43.0±11.5 years,and the mean level of NAD^(+)was 31.3±5.3μmol/L.Nabothian cysts occurred in 184(27.7%)participants,with single and multiple cysts in 100(15.0%)and84(12.6%)participants,respectively.The total nabothian cyst prevalence gradually decreased from37.4%to 21.6%from Q1 to Q4 of NAD^(+)and the prevalence of single and multiple nabothian cysts also decreased across the NAD^(+)quartiles.As compared with the highest NAD^(+)quartile(≥34.4μmol/L),the adjusted odds ratios with 95%confidence interval of the NAD^(+)Q1 was 1.89(1.14–3.14)for total nabothian cysts.The risk of total and single nabothian cysts linearly decreased with increasing NAD^(+)levels,while the risk of multiple nabothian cysts decreased more rapidly at NAD^(+)levels of 28.0 to35.0μmol/L.Conclusion:Low NAD^(+)levels were associated with an increased risk of total and multiple nabothian cysts.
基金This work has been supported by the COMET-K2“Center for Symbiotic Mechatronics”of the Linz Center of Mechatronics(LCM)funded by the Austrian federal government and the federal state of Upper Austria.
文摘This article is about illustrating a workflow for incorporating reliability measures to typical electric machine design optimization scenarios.Such measures facilitate comparing designs not only for rated conditions,but also allow to analyze their performance in the presence of unevitable tolerances.Consequently,by additionally considering reliability or robustness as objectives compared to conventional optimization scenarios,designs featuring low parameter sensitiveness can be obtained.The analysis of the design’s reliability as part of solving optimization problems involves a significant increase in required numerical evaluations.To minimize the associated prolongation of the runtime,an approach featuring a design of experiments based reduction of required computations and a consequent surrogate modeling technique is presented here.After successful training,the metamodel can be applied for fast evaluating lots of different parameter combinations.A test problem is defined and analyzed.Based on the observed findings,the necessity of incorporating robustness evaluations to machine design optimization becomes evident.In addition,the derived models allow for studying the impact of any tolerance-affected parameter on the machine performance in detail.This facilitates further beneficial studies,as for instance the analysis of selected changes of tolerance levels rather than a general minimization of the respective ranges which usually is associated with high production cost.
基金supported by the Foundation for Polish Science through the IRA Programme financed by EU within SG OP Programmesupport by the Austrian Science Foundation-FWF (P31423 and P26830)the Austrian Exchange Service (OAD) Project PL-01/2017
文摘The interplay of magnetic and semiconducting properties has been in the focus for more than a half of the century. In this introductory article we briefly review the key properties and functionalities of various magnetic semiconductor families, including europium chalcogenides, chromium spinels, dilute magnetic semiconductors, dilute ferromagnetic semiconductors and insulators, mentioning also sources of non-uniformities in the magnetization distribution, accounting for an apparent high Curie temperature ferromagnetism in many systems. Our survey is carried out from today's perspective of ferromagnetic and antiferromagnetic spintronics as well as of the emerging fields of magnetic topological materials and atomically thin 2D layers.
文摘Three recent breakthroughs due to AI in arts and science serve as motivation:An award winning digital image,protein folding,fast matrix multiplication.Many recent developments in artificial neural networks,particularly deep learning(DL),applied and relevant to computational mechanics(solid,fluids,finite-element technology)are reviewed in detail.Both hybrid and pure machine learning(ML)methods are discussed.Hybrid methods combine traditional PDE discretizations with ML methods either(1)to help model complex nonlinear constitutive relations,(2)to nonlinearly reduce the model order for efficient simulation(turbulence),or(3)to accelerate the simulation by predicting certain components in the traditional integration methods.Here,methods(1)and(2)relied on Long-Short-Term Memory(LSTM)architecture,with method(3)relying on convolutional neural networks.Pure ML methods to solve(nonlinear)PDEs are represented by Physics-Informed Neural network(PINN)methods,which could be combined with attention mechanism to address discontinuous solutions.Both LSTM and attention architectures,together with modern and generalized classic optimizers to include stochasticity for DL networks,are extensively reviewed.Kernel machines,including Gaussian processes,are provided to sufficient depth for more advanced works such as shallow networks with infinite width.Not only addressing experts,readers are assumed familiar with computational mechanics,but not with DL,whose concepts and applications are built up from the basics,aiming at bringing first-time learners quickly to the forefront of research.History and limitations of AI are recounted and discussed,with particular attention at pointing out misstatements or misconceptions of the classics,even in well-known references.Positioning and pointing control of a large-deformable beam is given as an example.
文摘In the current study poly(lactic acid)PLA composites with a 3 wt%and 5 wt%of nanofibrillated cellulose(NFC)were produced by 3D-printing method.An enzymatic pretreatment coupled with mechanical fibrillation in a twin screw extruder was used to produce high consistency NFC.Scanning electron microscopy(SEM)equipped with Fibermetric software,FASEP fiber length distribution analysis,Furrier transform infrared spectroscopy(FT-IR),thermogravimetric analysis(TGA),tensile tests,impact tests and differential scanning calorimetry were used to characterize NFC and PLA/NFC composites.The results of the fiber length and width measurements together with the results of the SEM analysis showed that enzymatic hydrolysis coupled with a twin screw extrusion could effectively reduce the diameter and length of cellulose fibers.The produced NFC consisted of microand nanosized fibers entangled in a characteristic 3D-network.Based on the FT-IR analysis,no new bonds were formed during the enzymatic hydrolysis or fibrillation process.The TGA analysis confirmed that produced NFC can be used in hightemperature extrusion processing without NFC degradation.During the PLA/NFC composites preparation the NFC agglomerates were formed,which negatively influenced PLA/NFC composites impact properties.The slightly improved tensile strength and elastic modulus were reported for all composites when compared to the neat PLA.The elongation at break was not affected by the NFC addition.No significant differences in thermal stability were detectable among composites nor in comparation with the neat PLA.However,the crystallinity degree of the composite containing 5 wt%NFC was increased in respect to the neat PLA.
基金supported by the COMET-K2“Center for Symbiotic Mechatronics”of the Linz Center of Mechatronics(LCM)funded by the Austrian federal government and the federal state of Upper Austria.
文摘This work is about analyzing surface mounted permanent magnet machines regarding their sensitiveness related to erroneous magnet positioning.A finite element analysis based approach is presented and different topologies in terms of slot and pole count are compared.The study further includes the analysis of multiple magnet widths and stator teeth widths.By contrast to most of previous studies,the work is based on evaluating the cumulative distribution function of the cogging torque in case of non-idealities.A Monte Carlo importance sampling based strategy is focused.This approach facilitates studying arbitrary tolerance distributions.Results reveal that topologies with particularly promising rated cogging torque behaviour exhibit the most significant performance degradation in presence of tolerances.A linear relationship is identified for cogging torque performance as function of the accuracy in magnet positioning.Results emphasize the necessity of tolerance analyses for electric machine design to not overrate their performance in the presence of manufacturing uncertainties.
文摘The intensive research performed in the field of conjugated polymers during the last four decades gave rise to a new class of materials, in which the electrical conductivity can be adjusted to cover the entire range from pure insulator to metallic [1]. Their ease of processability, low weight, mechanical flexibility and potential low production cost triggered the use of these "plastic semiconductors" for electronic device applications. Nowadays, organic light emitting diodes (OLED) [2] based on conjugated polymers are entering the market and organic field effect transistors (OFET) [3] are considered for replacing a:Si thin film transistors (TFT).
文摘Modern computer techniques have been in use for several years to generate three-dimensional visualizations of human anatomy. Very good 3-D computer models of the human body are now available and used routinely in anatomy instruction. These techniques are subsumed under the heading “virtual anatomy” to distinguish them from the conventional study of anatomy entailing cadavers and anatomy textbooks. Moreover, other imaging procedures (X-ray, angiography, CT and MR) are also used in virtual anatomy instruction. A recently introduced three-dimensional post-processing technique named Cinematic Rendering now makes it possible to use the output of routine CT and MR examinations as the basis for highly photo-realistic 3-D depictions of human anatomy. We have installed Cinematic Rendering (enabled for stereoscopy) in a high-definition 8K 3-D projection space that accommodates an audience of 150. The space’s projection surface measures 16 × 9 meters;images can be projected on both the front wall and the floor. A game controller can be used to operate Cinematic Rendering software so that it can generate interactive real-time depictions of human anatomy on the basis of CT and MR data sets. This prototype installation was implemented without technical problems;in day-to-day, real-world use over a period of 22 months, there were no impairments of service due to software crashes or other technical problems. We are already employing this installation routinely for educational offerings open to the public, courses for students in the health professions, and (continuing) professional education units for medical interns, residents and specialists—in, so to speak, the dissecting theater of the future.
文摘Since the 1980s, various techniques have been used in the field of medicine for the post-processing of medical imaging data from computed tomography (CT) and magnetic resonance (MR). They include multiplanar reformations (MPR), maximum intensity projection (MIP) and Volume Rendering (VR). This paper presents the prototype of a new means of post-processing radiological examinations such as CT and MR, a technique that, for the first time, provides photorealistic visualizations of the human body. This new procedure was inspired by the quality of images achieved by animation software such as programs used in the entertainment industry, particularly to produce animated films. Thus, the name: Cinematic Rendering. It is already foreseeable that this new method of depiction will quickly be incorporated into the set of instruments employed in socalled virtual anatomy (teaching anatomy through the use of radiological depictions of the human body via X-ray, CT and MR in addition to the use of computer animation programs designed especially for human anatomy). Its potential for medical applications will have to be evaluated by future scientific investigations.
文摘A 7-year-old boy presented with cerebellar ataxia with reduced tonicity, deficits of the fine and gross motor coordination skills and vestibular stimulus processing, as well as significantly delayed language development. MR imaging showed the so-called “molar tooth sign”, which was highly pathognomonic for the Joubert-Syndrome—an inherited cerebellar ataxia with a variety of clinical symptoms—and related entities. It is caused by a complex malformation of the cerebellar vermis and the midbrain. The cerebellar vermis is hypoplastic or completely absent;at the same time, the superior cerebellar peduncles are thickened. There is a lack of normal decussation of the fiber tracts in mesencephalon, which follow an abnormal horizontal course, as well as a lack of the decussation of the corticospinal fiber tracts in the caudal medulla oblongata and deformity of the 4th ventricle. Clinically, the triad of cerebellar ataxia, developmental retardation, and abnormal eye movements is indicating a related syndrome of this spectrum. The appearance of the involved children is characterized by dysmorphic facial features with epicanthus, broad nose bridge, low set ears and typically triangularly shaped and opened mouth. The diagnosis is usually made by imaging and clinical findings. Recently, advantages were made in genetic research on the Joubert syndrome and interesting findings published about diffusion tensor imaging and tractography. However, standard MR imaging, applying an adequate imaging protocol including sequences with excellent T1 contrast and 3D imaging with isotropic spatial resolution allowing reconstructions in all orientations, remains an essential tool for making this diagnosis.
基金The authors acknowledge the support by the Linz Center of Mechatronics(LCM)in the framework of the Austrian COMET-K2 program。
文摘This paper addresses the application of the continuum mechanics-based multiplicative decomposition for thermohyperelastic materials by Lu and Pister to Reissner’s structural mechanics-based,geometrically exact theory for finite strain plane deformations of beams,which represents a geometrically consistent non-linear extension of the linear shear-deformable Timoshenko beam theory.First,the Lu-Pister multiplicative decomposition of the displacement gradient tensor is reviewed in a three-dimensional setting,and the importance of its main consequence is emphasized,i.e.,the fact that isothermal experiments conducted over a range of constant reference temperatures are sufficient to identify constitutive material parameters in the stress-strain relations.We address various isothermal stress-strain relations for isotropic hyperelastic materials and their extensions to thermoelasticity.In particular,a model belonging to what is referred to as Simo-Pister class of material laws is used as an example to demonstrate the proposed procedure to extend isothermal stress-strain relations for isotropic hyperelastic materials to thermoelasticity.A certain drawback of Reissner’s structural-mechanics based theory in its original form is that constitutive relations are to be stipulated at the one-dimensional level,between stress resultants and generalized strains,so that the standardized small-scale material testing at the stress-strain level is not at disposal.In order to overcome this,we use a stress-strain based extension of the Reissner theory proposed by Gerstmayr and Irschik for the isothermal case,which we utilize here in the framework of the considered thermoelastic extension of the Simo-Pister stressstrain law.Consistent with the latter extension,we derive non-linear thermo-hyperelastic constitutive relations between stress-resultants and general strains.Special emphasis is given to linearizations and their consequences.A numerical example demonstrates the efficacy of the structural-mechanics approach in large-deformation problems.
文摘Spinal dural arteriovenous fistulas (SDAVF) account for about 70% of all spinal AV shunts. We re-port on a 56-year-old male patient with progressive neurological symptoms. Pre- and post-contrast MR imaging of the spine, including contrast-enhanced MR angiography was done on a 1.5 T MR scanner. In addition a special (pre-contrast) 3D turbo-spin-echo sequence with variable flip angle evolution (SPACE) was performed providing a slice thickness of 0.9 mm. T2-weighted images showed extensive widened and tortuous vascular structures with typical flow voids intradurally due to dilated pial veins. The origin of the spinal dural arteriovenous fistula was found to be the radiculomeningeal artery at level D10/11 on the left side, visualized by the T2-weighted 3D SPACE sequence and CE MRA. After imaging the patient was referred to an interventional neuroradiology department for therapy. With the detailed information from MR imaging concerning the fistula level the interventional radiologist was able to find the fistula immediately and consequently treated it successfully by endovascular therapy. Interpreting the MR images of this obvious case of a SDAVF, SPACE sequence after post processing with 3D MPR software directly led to the location of the AV shunt at D10/11 on the left side, better than 3D contrast-enhanced MR angiography did. Therefore, SPACE can be a useful adjunct in further evaluation of spinal dural arteriovenous fistula and especially in defining fistula level.
文摘A significant impact of this work on the use of polymers is expected because the developed organo-nano particles (ONP) mixed into standard polymers will make them unique and traceable. The doping of polymers with non migrating ONP was demonstrated and applications for the recycling of plastics were discussed. Thus, perylene derivatives were linked to polymerisable vinyl groups and copolymerized under RAFT conditions (Reversible Addition Fragmentation chain Transfer) with styrene and methylmethacrylate, respectively, to obtain fluorescent ONP with sizes of 40 nm or even less and narrow distributions of molecular weight in most cases with polydispersities PD of 1.1 and lower.
文摘The paper focuses on links between the EU ETS (European Union Emissions Trading Scheme) and selected (domestic) greenhouse gas ETS (emissions trading schemes) from Asia and North America which could open up a perspective to keep the idea of emissions trading alive on a global scale and confront the actual uncertainty in future climate policy. The approach consists of investigating qualitatively the essential requirements of this alternative bottom-up approach. It is evaluated if variations or inconsistencies in the structure and design of domestic ETS as well as legal and institutional characteristics harm or facilitate the concept of linking with the EU ETS. The evaluation of systems leads to the exclusion of systems with voluntary character, relative caps, unrestricted borrowing and price caps from the group of potential linking candidates.
文摘This article is about a comparison of different measures for determining the robustness or reliability of electric machine designs in the presence of inevitable tolerances.The selected criteria shall be suitable for concurrent evaluation in the course of solving state-of-the-art large scale multi-objective opti-mization problems.In the past,besides particularly customized criteria,mainly gradient based measures,worst case information,or standard deviation based quantities were considered.In this work,the quantile measure is introduced for electric machine design optimization and compared with the existing solutions.The evaluation of a design’s robustness is typically examined based on finite element simulations.As for most measures a signif-icant number of parameter combinations and thus computations are required,a surrogate model assisted approach is presented to minimize computational effort and runtime.A test problem is defined and analyzed to illustrate the differences of selected robustness measures.Results reveal the importance of considering robustness in the optimization process.Moreover,a careful choice of appropriate measures has to be taken.Selected designs are compared and conclusions and an outlook on future activities are presented.
文摘This paper explores how empirical capability approach studies assess well-being for young and old generations in affluent countries, defined as high-income OECD countries. After a brief overview on the theoretical capability background and empirical core decisons, the authors discuss empirical capability studies on the well-being of children, adolescents and the elderly. The authors find that the issues of child and youth well-being have been increasing interested by capability researchers while despite of the importance of demographic change, few researchers deal with old-age issues. The authors conclude that for young as well as old generations, capability approach studies confirm that income assessment is not sufficient to capture well-being for the young and the old but has to be enriched by a more comprehensive perspective on capabilities and functionings. Moreover, it is recommendable and issues that have already entered the agenda of studies on for research on elderly to adopt research methods, questions capabilities of children and young adults. As capability sets for both, young and old generations are in general characterized by changes, i.e., expansions in the case of children, declines in the case of older people, both may benefit from a more dynamic perspective on life cycles on their way to potential dynamic capability theories and empirics.
文摘Composites based on melamine formaldehyde resins filled with exfoliated graphite or so called nanographite have been prepared to achieve electrical conductivity and improve mechanical strength and thermal stability. The nanographite was synthesized by thermal treatment of oxidized graphite and the incorporation into the melamine matrix was accomplished during the melamine formaldehyde reaction. A homogenous dispersion of the filler in the matrix and the forming of a connecting network based on graphite sheets were proved by SEM images. The graphite filler was able to increase the flexural strength of molded testing specimens compared to unfilled resins and electrical conductivity was achieved starting at 2 wt% nanographite.
文摘Carbon fibers composites are well</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">known as high tech materials but are also recognized as a problem after use as they have to be deposited in landfills. Pyrolysis is an attractive process for recycling carbon fibers from used composites as well as offcuts from prepregs. Pyrolysis of carbon fiber composite prepregs is carried out in a pilot plant with a single screw reactor. The pyrolysis products, carbon fibers and pyrolysis vapor are fully characterized. Variation of pyrolysis temperature is carried out to obtain carbon fibers with the best possible surface properties. In order to compare the mechanical properties of the recycled carbon fibers with virgin material, composite materials with polyamide are produced and their properties compared.