bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of turbulence models fitted to site, and their impact on the response of a bottom-fixed wind turbine
Authors: Nybø A , Nielsen FG , Godvik M
Published: September 2021

This study compares a wind field recommended by the wind turbine design standards to more realistic wind fields based on measurements. The widely used Mann spectral tensor model with inputs recommended by the standard, is compared to FitMann, the Mann model with inputs fitted to measurements and TIMESR; using measured time series combined with the Davenport coherence model. The Mann model produces too low energy levels at the lowest frequencies of the wind spectra, while the wind spectra generated by FitMann approaches the measured values. TIMESR reproduces the measured spectral values at all frequencies. The different models give similar vertical coherence, while the Mann and FitMann models give lower horizontal coherence than TIMESR. Investigating the wind loads on a bottom-fixed 10-MW wind turbine, the spectra for the tower bottom fore-aft and blade root flapwise bending moment follow the shape of the wind spectra closely at low frequencies. The low-frequency range is important for the blade root and in particular the tower bottom bending moment. Thus, the TIMESR model, followed by FitMann, is assumed to give the most accurate fatigue estimates. For the specific situation analysed in this study, the FitMann model gives only 18 and 5 % lower estimates than TIMESR of the tower bottom and blade root damage equivalent bending moments, while the Mann model gives 27 % and 12 % lower estimates. The tower top yaw and fore-aft bending moments depend on the wind coherence. For the specific situation analysed in this study, the FitMann model gives 9 and 5 % higher estimates of the tower top yaw and tower top damage equivalent (bending) moments compared to TIMESR, while the Mann model gives 23 % and 18 % higher estimates. Since only measurements of the vertical coherence are available, it is not clear which model is superior for the tower top moments. However, the importance of a proper coherence model is documented.
Hybrid analysis and modeling for next generation of digital twins
Authors: Pawar Suraj , Ahmed Shady E. , San Omer , Rasheed Adil
Published: September 2021

The physics-based modeling has been the workhorse for many decades in many scientific and engineering applications ranging from wind power, weather forecasting, and aircraft design. Recently, data-driven models are increasingly becoming popular in many branches of science and engineering due to their non-intrusive nature (i.e., they are equation-free) and online learning capability. Despite the robust performance of data-driven models, they are faced with challenges of poor generalizability and difficulty in interpretation. These challenges have encouraged the integration of physics-based models with data-driven models, herein denoted hybrid analysis and modeling (HAM). We propose two different frameworks under the HAM paradigm for applications relevant to wind energy in order to bring the physical realism within emerging digital twin technologies. The physics-guided machine learning (PGML) framework reduces the uncertainty of neural network predictions by embedding physics-based features from a simplified model at intermediate layers and its performance is demonstrated for the aerodynamic force prediction task. Our results show that the proposed PGML framework achieves approximately 75% reduction in uncertainty for smaller angle of attacks. The interface learning (IL) framework illustrates how different solvers can be coupled to produce a multifidelity model and is successfully applied for the Boussinesq equations that govern a broad class of transport processes. The IL approach paves the way for seamless integration of multi-scale, multi-physics and multi-fidelity models (M
3 models).
Direct and fast probabilistic assessment of long term monopile load distribution from combined metocean data and fully nonlinear wave kinematics
Authors: Tornfeldt Sørensen J V , Hansen H F , Mandviwalla X , Pierella F , Bredmose H
Published: September 2021

A novel method is introduced to determine the long-term extreme value distribution of variables with an associated short-term distribution. The method is applicable to e.g. the extreme value with a return period of 10.000 years for wave height, crest height of waves as well as wave-induced response and loads on offshore wind turbine monopiles. The extreme values are determined by a combination of a joint probabilistic description of the met-ocean environment and of a recently developed database of fully nonlinear wave kinematics computations. For two benchmark monopile structures, representative for the conditions at Dogger Bank and the German Bight in the North Sea, the one-hour max value of crest height, inline force and overturning moment are computed via the Rainey slender-body force model. Convolution with the joint probability of the sea state parameters in the nondimensional space of wave steepness and Ursell parameter leads to the marginal probability distribution for these parameters up to a 10.000 year return period and properly accounts for the uncertainty of the extreme value parameters in also the short-term distributions. It is found that the best extreme value fit is generally obtained with a third-order polynomial fit within the space of steepness and Ursell parameter. Compared to the Forristall crest height distribution, the inclusion of full nonlinearity leads to larger crest heights at low return period levels. However, due to its realistic treatment of the breaking limitation, lower crests are predicted at the 10.000 year level for the two positions considered in the North Sea. With further verification of the wave kinematics in combination with load models and a thorough comparison to present engineering practice, the proposed methodology provides a robust future solution for directly estimating extreme value distributions of loads and response of offshore wind turbine monopiles.
A non-intrusive parametric reduced order model for urban wind flow using deep learning and Grassmann manifold.
Authors: Tabib Mandar V , Pawar Suraj , Ahmed Shady E. , Rasheed Adil , San Omer
Published: September 2021

In this study, we present a parametric non-intrusive reduced order modeling framework as a potential digital twin enabler for fluid flow related applications. The case study considered here involves building-induced flows and turbulence with inlet turbulence value as a parameter. The framework proposed employs a Grassmann manifold interpolation approach (GI) for obtaining basis functions corresponding to new values of parameter, and exploits the time series prediction capability of long short-term memory (LSTM) recurrent neural network for obtaining temporal coefficients associated with the new basis functions. The methodology works in the following way: (i) in the training phase, the LSTM model is trained on the modal coefficients extracted from the high-resolution data using proper orthogonal decomposition (POD) transform for the known values of parameter, and (ii) in the testing phase, the trained model predicts the modal coefficients for the total time recursively based on the initial time history for the new value of parameter. Then, we reconstruct the flow fields for the new value of parameter (new inlet turbulent value) using the GI modulated basis functions and LSTM predicted associated temporal coefficients. To assess the performance of the proposed model, the ROM-LG predictions are compared with the high-dimensional full-order model solutions using L1 and L2 error analyses as well as with the conventional POD based ROM (ROM-POD) solutions. The results indicate that the non-intrusive ROM (ROM-LG) framework yields a stable solution for the velocity fields and for short-term prediction of dynamic turbulent kinetic energy fields. This work has scope for further development and will be useful for building-integrated wind energy and urban drone operation in a smart-city digital twin platform.
Reduced order models for finite-volume simulations of turbulent flow around wind-turbine blades.
Authors: Tsiolakis Vasileios , Kvamsdal Trond , Rasheed Adil , Fonn Eivind , Brummelen Harald van
Published: September 2021

The computational cost of the design optimisation of wind turbines, as well as the optimisation of the operation and maintenance of offshore wind farms represents a limitation to the application of conventional simulation methods. New techniques such as reduced order modelling (ROM) and technologies such as hybrid-analysis methods and digital twins have increased in popularity due to their ability to deliver numerical results at a significant speed-up with reasonable accuracy. This work presents a hybrid projection-based proper orthogonal decomposition (POD) strategy applied to transient turbulent flow problems. Key feature of this work is the applicability of the methodology to high Reynolds number cases and the stabilisation of pressure in the online phase via the assembly of the so-called pressure Poisson equation. Another significant part of this work is the implementation of an interpolation scheme for the eddy viscosity field in the classical POD-Galerkin strategy. The sampling procedure and the calculation of the reduced operators in the offline phase is carried out using the finite volume method (FVM), OpenFOAM’s libraries specifically, while the construction of the reduced basis and the solution of the online phase is carried out in Python. The capability of the resulting ROM is tested using the two-dimensional flow around a NACA0015 airfoil at 17° angle of attack with Reynolds number of approximately 300 000.
Preliminary assessment of yaw alignment on a single point moored downwind floating platform
Authors: Urbán Albert M. , Voltà Laura , Lio W. H. , Torres Rocio
Published: September 2021

The ability of Single Point Moored Downwind platforms to align with the main wind direction, depends on the floater and wind turbine design. When co-directionality between wind, waves and current exists, there is no external loading that can difficult the floater alignment. On the other hand, when certain metocean conditions take place, such as a crosscurrent, a misaligning force can prevent the floater to face towards the main wind direction.

In this study, the PivotBuoy floater is used to evaluate the Single Point Moored platform’s ability to align with the main wind direction. The platform dynamics are assessed under irregular wind and wave conditions for current speeds ranging from 0.1 m/s to 1.5 m/s for different wind-current alignments. Two solutions for improving the platform alignment are presented and compared against the baseline case, for the extreme and unusual condition where the platform is operating with a crosscurrent of 90° and 0.4 m/s. Both proposed strategies, an active, based on Individual Pitch Control, and a passive where a static nacelle yaw offset is used, are able to reduce the mean alignment to be within 0.8° compared to the baseline case of 18.7°. The preliminary analysis show promising results for the proposed solutions but need to be further investigated in detail.
Study on the feasibility of applying DNA molecular marking technology to anti-counterfeiting of artifacts and artworks
Authors: Wu H C , Chu W S , Li I C , Wang H L , Huang B W
Published: September 2021

Artifacts and artworks record the wisdom of human activities and civilization. They not only trace an era’s history or reflect the aesthetics of contemporary art and different lifestyles, but they also enable us to understand the codes of wisdom passed down from our ancestors and explore history. Therefore, determining artworks’ authenticity is increasingly important. The objective of study was to investigate the feasibility of applying DNA molecular marking technology to anti-counterfeiting of artifacts and artworks. The DNA sequence used for testing in this research came from the team’s previous studies. A genetic substance was embedded in the artwork to test the DNA’s feasibility, repeatability, and reproducibility, as well as the difference in the deterioration conditions of the DNA embedded artwork. Our results showed that about 70% to 90% of the DNA fragments remained intact. Therefore, we conclude that embedding the extracted DNA directly into a painting and detecting whether the DNA fragments persist after reconstitution could help us to determine the authenticity of a painting
Tracking control of a precision stage with NARX neural network for friction compensation
Authors: Irfanda I T , Shen J C
Published: September 2021

The objective of this study is to develop a neural network controller for the friction compensation. The purpose models are used as an inverse model of the frictional force and dynamic behaviour of a system. A proportional-integral-derivative (PID) controller and a neural network system architecture are developed for the Nonlinear Autoregressive with Exogenous inputs (NARX) neural network were proposed to control a precision stage. Firstly, a test signal was used to drive the stage then the derived data was used to train a NARX neural network. This neural network model is the inverse dynamic model of the stages and friction force. An architectural approach of NARX showing promising qualities for dynamic system applications, is analysed in this paper. Utilization of this model is as an estimate of the driving force related with the dynamics of the system against displacement, and is then used as a feed-forward controller to compensate for friction errors. Finally, the experimental systems are established and the result shows that the combination of PID and NARX can improve the tracking performance of the precision stage.
Applying cyber physical system architecture concept to the design and manufacturing of blood glucose monitoring systems to provide man-machine interactions and intelligent automation
Authors: Kuo H Y , Chang H , Cheng Y H , Shaw J S , Lee R
Published: September 2021

The current design and manufacturing of blood glucose monitoring systems (BGMS) cannot resolve many current problems. Even with recent new advances on 100% non-damaging quality check and laser repair for the defective test strips found, it is still not enough. With the new internet, a new revolutionary architectural concept based on cyber physical system (CPS) is highly recommended to implement on the design and manufacturing of BGMS. This paper presents many unique benefits that can be achieved. The implementation of CPS to the design of BGMS interconnects the uses of glucose meters, test strips and control solutions with the manufacturing systems through internet to enhance the safety and performance of the BGMS, and to provide man-machine interactions and intelligent automation. Furthermore, the implementation of CPS to the manufacturing of BGMS further interconnects sensors and information feedbacks from different work stations to allow the manufacturing systems to be self-aware, self-adaptable and self-configurable, in order to reduce manpower, defective rate and production down time for better productivity. This new concept will bring in revolutionary approaches into the design and manufacturing of BGMS, in order to upgrade product performance, increase product competitiveness and create new business opportunities, by providing man-machine interactions and intelligent automation. Apart from that, the implementation of CPS architecture to the design and manufacturing of BGMS does not necessarily increase the costs of producing BGMS.
Finite element analysis of cold drawing of stainless steel bars
Authors: Hwang Y M , Lin M R , Wu C H , Tsui H S R
Published: September 2021

Drawing is a metal forming process that is carried out by pulling a work piece through a die cavity. During the process, the cross-sectional area of the work piece reduces and the shape of the product is the same as that of the die cavity. In traditional industries, the required accuracy and quality can be achieved through multiple tryouts, by which a large amount of testing samples and time are required and accordingly results in the increase in production cost and decrease in productivity. Cold drawing is an effective way to produce bars or wires with high precision in product size. However, there is still no appropriate quantitative formula to determine how the dimensions of the die and the forming parameters affect the geometric dimensions of the product. In recent years, the progress of simulation technology allows us to investigate the effects of forming parameters on finished products dimensions. However, there was no literature discussing the effects of various parameters on the precision of the product dimensions. In this paper a finite element model is established to analyze the elastoplastic deformation of the bar inside the die cavity. An empirical formula including various forming parameters is established from a series of simulation results, and the precision can reach within 0.1%.
Study on the characteristics of the materials and manufacturing quality to shrapnel-type couplings properties
Authors: Chen C M , Chang H L , Lin C C
Published: September 2021

With the development and application for the ultra-precision machinery industries and smart machinery have become prosperous. The precision transmission sub-system is an important part of the precision machinery equipment and smart machinery industries. Then shrapnel-type coupling is an important part of the precision transmission system. In the shrapnel-type couplings with high precision, high reliability, and high efficiency. The design of shrapnel-type couplings needs to correct and improved in the manufacturing with very high-precision inspection equipment, and expert measurement technology. The high quality of shrapnel-type couplings, materials and manufacturing qualities are the main factor for high precision, high reliability, and high efficiency. This paper will be a depth study of the body materials and manufacturing qualities of shrapnel-type couplings. The inner hole contact surfaces of the shrapnel-type couplings to connect between each other connecter tested the properties of the coupling via toque-torque angle testing equipment with changing the shrapnel-type couplings body materials and manufacturing different roughness of inner hole. The key characteristics that affect the torsional rigidity and failure torque of the coupling grasped are found out using the self-developed toque-twist angle testing machine. The body of the shrapnel-type couplings made with 7075 aluminium alloy and 6061 aluminium alloy. Through experiments, we can understand the influence of different materials bodies on the torsional rigidity and failure moment of the shrapnel-type couplings. From experimental results, that 7075 aluminium alloy is better than 6061 aluminium alloy of torsional rigidity or failure moment. As the inner hole surface roughness of the shrapnel-type couplings smaller has a higher failure torque of coupling.
Methodology to incorporate damaged BWR spent fuel as contents in the NAC-UMS® storage system
Authors: Su M , Carver G , Chen C C , Yang C W , Shih C L
Published: September 2021

Following Taiwan’s nuclear waste management policy, INER launched Taiwan’s first Independent Spent Fuel Storage Installation (ISFSI) project in 2005. The technology of dry storage system adopted is NAC-UMS system. INER made some design modifications of NAC-UMS system in order to accommodate the constraints at Chin-Shan Nuclear Power Plant (CSNPP). The modified UMS was named as INER High Performance System (INER-HPS). The corresponding Safety Analysis Report (SAR) of ISFSI was approved by AEC on November of 2008. Through years of dedication, the first dry run test has been accomplished on November 2012. INER-HPS is capable to cover most of the spent fuels dry storage needs in Taiwan with current NAC-UMS License. The current CoC for NAC-UMS includes undamaged BWR fuel with a burn-up of not greater than 45 GWD/MTU. For the purpose of NAC-UMS to incorporate damaged BWR fuel as approved contents, INER and NAC further enter into cooperation to developing and licensing NAC-UMS to include up to four BWR damaged fuel cans and a new BWR damaged fuel basket. This paper summarized the project progress, results of trial fabrication of damaged fuel can, and the methodology to incorporate damaged BWR spent fuel as contents in the NAC-UMS storage system.
Finite element analysis of plastic hollow core sandwich composites
Authors: Gomber D , Ramezani M
Published: September 2021

Applications of sandwich composites are increasing as they continue to develop. The reason for the growth in development and the rising demand for sandwich composites in numerous industries is due to its ability to achieve high stiffness and strength, while simultaneously being lightweight in comparison to traditional materials. 3D printed plastic hollow core sandwich composites were focused on in this study where a bioplastic, Polylactic Acid (PLA), was compared to a conventional plastic, Polypropylene (PP). The study investigated the effects of varying core and face sheet parameters on the mechanical properties of 3D printed plastic core sandwich composites to obtain the optimum sandwich composite structure. A finite element model was developed in ANSYS Workbench to conduct the study. Numerical results were compared with experimental results, and both results revealed that the mechanical properties of sandwich composite structures are certainly influenced by the core and face sheet parameters. An optimum sandwich composite structure cannot be defined for a general case, as it depends on the application for which it is being designed. Hence, different optimum structures were determined for different desired mechanical properties.
Study on size effects in micro deep drawing of stainless steel foil
Authors: Yuan S N , Xie H B , Jia F H , Wu H , Pan D , Wang T X , Zhou C , Jiang Z Y
Published: September 2021

In this paper, the mechanism of processing parameters, such as lubrication conditions, grain size and foil thickness, on micro deep drawing (MDD) of stainless steel 304 (SUS304) foil has been investigated. The dry and glycerin-based nano-additive TiO2 lubricant with different concentrations were selected to study the effects of lubrication on MDD process. Four stainless steel samples with different thicknesses of 20, 30, 40 and 50 μm were employed in this study. Each foil was annealed under 950, 980 and 1050 °C respectively to obtain different grain sizes of the samples. The formed cups qualities in terms of surface roughness, wrinkling and earing defects were analysed, and the punch force-stroke curves and the stress-strain curves were studied in MDD. The experimental results show that 4.0 wt.% glycerin-based nano-additive TiO2 lubricant has the best lubrication effects due to its lowest drawing force and the better surface quality obtained, and the SUS304 foil with thinner thickness required smaller punch force, while the surface is more uneven in comparison with the thicker SUS304 foil. Moreover, the SUS304 foils annealed at lower temperature had smaller grains, and subsequently had smoother surface textures than those of SUS304 foils with larger grains annealed at higher temperature. The findings of size effects from lubrication, grain size and foil thickness obtained in this study will enhance the mechanism understanding of SUS304 foil deformation in MDD.
Exploring key aspects of art documentation and examination in curation technology-using Cheng-Shiu university conservation center’s project as a case study
Authors: Lin L C , Li I C
Published: September 2021

Current discussions of art documentation and examination focus on improving the artifact documentation and examination process, constructing databases, applying new technology, and conducting technical training of staff. For curators, museum collections, private collectors, artifact surveyors, and art gallery workers, documentation and examination are a critical stage in the process of archiving, exhibiting, conserving, and repairing artwork. Workers understand the function of documentation and examination, but not all workers understand these processes’ value and purpose. Apart from revealing the current condition of artifacts, what is the real value and purpose of artifact documentation and the examination process? This research considers the international and domestic projects completed by the conservation center of Cheng Shiu university and explores problems arising in the documentation and examination process for curation, art exhibitions, and collaboration with other museums, along with resolutions provided by the process. This research also examines the key roles played by the documentation and examination process in those cases. This paper emphasizes the importance of the documentation and examination process; moreover, this paper’s study of real cases demonstrates the practical applications of the documentation and examination process.
Design and analysis of component for non-rotor unmanned aerial vehicle
Authors: Shiau Y R , Fang J , Chen Y L
Published: September 2021

Unmanned aerial vehicles (UAVs) are widely applied in various industries and fields. Because they use a variety of rotor types, from single rotors to multi-rotors, UAVs offer a wide array of functions. However, continuously rotating rotors can be dangerous if they accidentally encounter foreign objects or bare hands. Therefore, non-rotor UAVs are the focus of discussion and modification in the present study. Non-rotor UAVs do not contain visible rotor mechanical components. Compared with the development of popularized multirotor UAVs, that of non-rotor UAVs is challenging in terms of structure and flight control. To address this challenge, wind tunnel structure models were developed in this study for different levels of aerodynamic force, and computer-aided engineering was used to conduct structural and flow field analyses to determine the key elements that reinforce non-rotor UAV structures. The research results revealed that the thickness and fillet design at the joint of the non-rotor UAV aerodynamic wind tunnel system were crucial factors influencing the system’s performance. Motor rotors can be embedded inside support structures to reduce airflow turbulence in the wind tunnel.
Remote sun tracing and solar energy generation system
Authors: Huang W C , Chiu M C , Yeh L J , Yeh L M
Published: September 2021

This paper aims to generate the most electricity on a solar board. A hemisphere suntracing-module composed of small solar boards is established. According to the electrical voltages of the small solar boards, the coordinates (angles) of the solar board with maximal electrical voltage will be recognized by the server port. With this, the server port will send the information to the client ports (the solar energy generation stations) via the internet. The client ports that wirelessly (with Wi-Fi module) connect to the individual microcontroller will direct the microcontroller to trigger two step motors to rotate to the related coordinates. All the main solar boards will be simultaneously adjusted to the best direction to generate the maximal solar electricity. The generated electricity will be stored in the related storage battery. For every time interval, the new coordinate will be recognized by the sun tracing module and then forwarded to the solar energy generation stations. The time interval can be predetermined on the server port.
Optimization of rectangular mufflers inserted with baffles at high-order-modes using differential evolution method
Authors: Cheng H C , Chiu M C , Chang Y C
Published: September 2021

Although rectangular mufflers have been widely used in industry, there has been scant research on both rectangular mufflers equipped with baffles under space-constrained conditions. Moreover, much muffler assessments have been restricted to lower frequencies using the plane wave theory. This has led to an underestimation of acoustical performances at higher frequencies. Beside, an analysis of three-dimensional waves propagating for mufflers using the finite element and boundary element methods is time-consuming in calculating the noise level. Also, the optimization of space-constrained mufflers is complicated. Therefore, to enhance the acoustical performance of mufflers, rectangular mufflers internally inserted with three kinds of baffles are presented. To illuminate the acoustical effect in high-order-modes and develop an optimally shaped muffler within a space-constrained situation, an eigen function in conjunction with a differential evolution is adopted. In this paper, a four-pole system matrix for evaluating the transmission loss of a muffler is derived using an eigen function.
Investigating the role of low level reinforcement reflex loops in insect locomotion
Authors: Goldsmith C A , Quinn R D , Szczecinski N S
Published: September 2021

Insects are highly capable walkers, but many questions remain regarding how the insect nervous system controls locomotion. One particular question is how information is communicated between the ‘lower level’ ventral nerve cord (VNC) and the ‘higher level’ head ganglia to facilitate control. In this work, we seek to explore this question by investigating how systems traditionally described as ‘positive feedback’ may initiate and maintain stepping in the VNC with limited information exchanged between lower and higher level centers. We focus on the ‘reflex reversal’ of the stick insect femur-tibia joint between a resistance reflex (RR) and an active reaction in response to joint flexion, as well as the activation of populations of descending dorsal median unpaired (desDUM) neurons from limb strain as our primary reflex loops. We present the development of a neuromechanical model of the stick insect (Carausius morosus) femur-tibia (FTi) and coxa-trochanter joint control networks ‘in-the-loop’ with a physical robotic limb. The control network generates motor commands for the robotic limb, whose motion and forces generate sensory feedback for the network. We based our network architecture on the anatomy of the non-spiking interneuron joint control network that controls the FTi joint, extrapolated network connectivity based on known muscle responses, and previously developed mechanisms to produce ‘sideways stepping’. Previous studies hypothesized that RR is enacted by selective inhibition of sensory afferents from the femoral chordotonal organ, but no study has tested this hypothesis with a model of an intact limb. We found that inhibiting the network’s flexion position and velocity afferents generated a reflex reversal in the robot limb’s FTi joint. We also explored the intact network’s ability to sustain steady locomotion on our test limb. Our results suggested that the reflex reversal and limb strain reinforcement mechanisms are both necessary but individually insufficient to produce and maintain rhythmic stepping in the limb, which can be initiated or halted by brief, transient descending signals. Removing portions of this feedback loop or creating a large enough disruption can halt stepping independent of the higher-level centers. We conclude by discussing why the nervous system might control motor output in this manner, as well as how to apply these findings to generalized nervous system understanding and improved robotic control.
Aerodynamic analysis of hummingbird-like hovering flight
Authors: Haider Naeem , Shahzad Aamer , Qadri Muhammad Nafees Mumtaz , Shams Taimur Ali
Published: September 2021

Flapping wing micro aerial vehicles are studied as the substitute for fixed and rotary wing micro aerial vehicles because of the advantages such as agility, maneuverability, and employability in confined environments. Hummingbird’s sustainable hovering capability inspires many researchers to develop micro aerial vehicles with similar dynamics. In this research, a wing of a ruby-throated hummingbird is modeled as an insect wing using membrane and stiffeners. The effect of flexibility on the aerodynamic performance of a wing in hovering flight has been studied numerically by using a fluid–structure interaction scheme at a Reynolds number of 3000. Different wings have been developed by using different positions and thicknesses of the stiffeners. The chordwise and spanwise flexural stiffnesses of all the wings modeled in this work are comparable to insects of similar span and chord length. When the position of the stiffener is varied, the best-performing wing has an average lift coefficient of 0.51. Subsequently, the average lift coefficient is increased to 0.56 when the appropriate thickness of the stiffeners is chosen. The best flexible wing outperforms its rigid counterpart and produces lift and power economy comparable to a real hummingbird’s wing. That is, the average lift coefficient and power economy of 0.56 and 0.88 for the best flexible wing as compared to 0.61 and 1.07 for the hummingbird’s wing. It can be concluded that a simple manufacturable flexible wing design based on appropriate positioning and thickness of stiffeners can serve as a potential candidate for bio-inspired flapping-wing micro aerial vehicles.
Modelling and Finite Element Analysis of an Aircraft Wing using Composite Laminates
Authors: Nath Arijeet , Anand Raunika , Desai Jeet , Sultan M.T.H. , Aravind Raj S.
Published: September 2021

The use of finite element analysis is increasingly gaining popularity in the design and analysis of aircraft structures. Also, composite materials in the manufacturing and design of aircraft structures are increasing due to their exceptional properties of high stiffness to weight ratio. Applications include Composite structures are made up of laminates with different fibre orientations, which adversely affects the property of the composites formed. For this study, the three main parts of the aircraft wing are considered for designing: the spars, the ribs, and the aircraft’s skin. The spars and made up of aluminium alloy, and the ribs are made up of structural steel. Two different wing models are designed. For Model 1, the skin is assigned Titanium alloy as a material, and for Model 2, CFRP (Carbon Fibre Reinforced Polymer) with resin epoxy is used as the skin material. The ribs are made of structural steel and the spars of titanium alloy for both models. This paper aims to compare the materials mentioned above to find the optimum strength to weight ratio. It was found that, for a given uniform load on the bottom of the aircraft’s skin, a weight reduction of 2.37 % was observed in favour of Model 2, the deformation was reduced by 51 per cent, and the von-Mises stress was reduced by ≈ 85%. This paper’s results can be used in manufacturing structural components of UAV, especially the wings due to lighter weight and more flexibility and durability than standard titanium alloys and the significant role played by the orientation of the plies in deciding the strength of the composite.
Goodwillie Approximations to Higher Categories
Authors: Heuts Gijs
Published: September 2021

We construct a Goodwillie tower of categories which interpolates between the category of pointed spaces and the category of spectra. This tower of categories refines the Goodwillie tower of the identity functor in a precise sense. More generally, we construct such a tower for a large class of∞\infty-categoriesC\mathcal {C}and classify such Goodwillie towers in terms of the derivatives of the identity functor ofC\mathcal {C}. As a particular application we show how this provides a model for the homotopy theory of simply-connected spaces in terms of coalgebras in spectra with Tate diagonals. Our classification of Goodwillie towers simplifies considerably in settings where the Tate cohomology of the symmetric groups vanishes. As an example we apply our methods to rational homotopy theory. Another application identifies the homotopy theory ofpp-local spaces with homotopy groups in a certain finite range with the homotopy theory of certain algebras over Ching’s spectral version of the Lie operad. This is a close analogue of Quillen’s results on rational homotopy.
Hume: A Very Short Introduction
Authors: Harris James A.
Published: September 2021

Hume: A Very Short Introduction provides a summary of the ideas and arguments of the philosopher and historian David Hume (1711–76), looking at Hume’s writings on human nature, morality, politics, and religion. Hume’s books need to be put in biographical, historical, and intellectual context. Hume’s major philosophical works, his essays on moral and political subjects, and his History of England constitute a very important part of his output. Hume’s arguments were complex but his conclusions had subtlety. Hume had an interesting and varied life, from his early solitary philosophical experiments to the achievement of fame and wealth. Hume was without doubt a major contributor to the European Enlightenment.
Stem Cells: A Very Short Introduction
Authors: Slack Jonathan
Published: September 2021

Stem Cells: A Very Short Introduction explains what stem cells are, why they are important, what scientists do with them, and how they might be used in the future. It tackles recent scientific and clinical developments surrounding stem cells, exploring their enormous therapeutic potential to treat diseases, such as macular degeneration, diabetes, and Parkinson’s disease. It also provides cautions against false claims from some clinics offering treatments and draws out lessons for the development of new stem therapies in the future. The VSI deals with the science and medicine of stem cells rather than with ethics, law, or politics.
Potentially inappropriate medications and their effect on falls during hospital admission
Authors: Damoiseaux-Volman Birgit A , Raven Kimmy , Sent Danielle , Medlock Stephanie , Romijn Johannes A , Abu-Hanna Ameen , van der Velde Nathalie
Published: September 2021

Objective

to investigate the effect of potentially inappropriate medications (PIMs) on inpatient falls and to identify whether PIMs as defined by STOPPFall or the designated section K for falls of STOPP v2 have a stronger association with inpatient falls when compared to the general tool STOPP v2.

Methods

a retrospective observational matching study using an electronic health records dataset of patients (≥70 years) admitted to an academic hospital (2015–19), including free text to identify inpatient falls. PIMs were identified using the STOPP v2, section K of STOPP v2 and STOPPFall. We first matched admissions with PIMs to those without PIMs on confounding factors. We then applied multinomial logistic regression analysis and Cox proportional hazards analysis on the matched datasets to identify effects of PIMs on inpatient falls.

Results

the dataset included 16,678 hospital admissions, with a mean age of 77.2 years. Inpatient falls occurred during 446 (2.7%) admissions. Adjusted odds ratio (OR) (95% confidence interval (CI)) for the association between PIM exposure and falls were 7.9 (6.1–10.3) for STOPP section K, 2.2 (2.0–2.5) for STOPP and 1.4 (1.3–1.5) for STOPPFall. Adjusted hazard ratio (HR) (95% CI) for the effect on time to first fall were 2.8 (2.3–3.5) for STOPP section K, 1.5 (1.3–1.6) for STOPP and 1.3 (1.2–1.5) for STOPPFall.

Conclusions

we identified an independent association of PIMs on inpatient falls for all applied (de)prescribing tools. The strongest effect was identified for STOPP section K, which is restricted to high-risk medication for falls. Our results suggest that decreasing PIM exposure during hospital stay might benefit fall prevention, but intervention studies are warranted.
Post-hospital falls incidence and risk factors among older adults: a systematic review and meta-analysis
Authors: Qian Xing Xing , Chen Zi , Fong Daniel Y T , Ho Mandy , Chau Pui Hing
Published: September 2021

Background

Post-hospital falls constitute a significant health concern for older adults who have been recently discharged from the hospital.

Objectives

To systematically summarise existing evidence on the incidence and risk factors for post-hospital falls among older adults.

Methods

A systematic review and meta-analysis was conducted. Six electronic databases were searched to identify cohort studies investigating the incidence and risk factors for post-hospital falls in older adults. The incidence and risk factors for post-hospital falls were extracted. The meta-analysis was used to calculate pooled incidences and 95% confidence intervals (CI). The meta-regression and subgroup meta-analysis were conducted to explore sources of heterogeneity in incidence proportions across the eligible studies. A qualitative synthesis was performed for the post-hospital falls risk factors.

Results

Eighteen studies from eight countries (n = 9,080,568) were included. The pooled incidence proportion of any and recurrent post-hospital falls was 14% (95% CI: 13%–15%) and 10% (95% CI: 5%–14%), respectively. Follow-up period, study quality, study country, setting, percentage of female subjects, percentage of subjects with previous falls and the primary data collection method for falls significantly contributed to the 64.8% of the heterogeneity in incidence proportions. Twenty-six risk factors for post-hospital falls were identified in the eligible studies, where biological factors were the most commonly identified factors. The highest risks were reported for previous falls, previous fractures, delirium and neurological diseases.

Conclusion

The findings of this study suggested future post-hospital falls prevention should prioritise the needs of older adults with the dominant risk factors. Further investigations into the period-specific incidence and socioeconomic and environmental risk factors for post-hospital falls are also required.
High-resolution imaging as a tool for identifying quantitative trait loci that regulate photomorphogenesis in Arabidopsis thaliana
Authors: Deslauriers Stephen D
Published: September 2021

A primary component of seedling establishment is the photomorphogenic response as seedlings emerge from the soil. This process is characterized by a reduced growth rate in the hypocotyl, increased root growth, opening of the apical hook and expansion of the cotyledons as photosynthetic organs. While fundamental to plant success, the photomorphogenic response can be highly variable. Additionally, studies of Arabidopsis thaliana are made difficult by subtle differences in growth rate between individuals. High-resolution imaging and computational processing have emerged as useful tools for quantification of such phenotypes. This study sought to: (i) develop an imaging methodology which could capture changes in growth rate as seedlings transition from darkness to blue light in real time, and (ii) apply this methodology to single-quantitative trait locus (QTL) analysis using the Cvi × Ler recombinant inbred line (RIL) mapping population. Significant differences in the photomorphogenic response were observed between the parent lines and analysis of 158 RILs revealed a wide range of growth rate phenotypes. Quantitative trait locus analysis detected significant loci associated with dark growth rate on chromosome 5 and significant loci associated with light growth rate on chromosome 2. Candidate genes associated with these loci, such as the previously characterized ER locus, highlight the application of this approach for QTL analysis. Genetic analysis of Landsberg lines without the erecta mutation also supports a role for ER in modulating the photomorphogenic response, consistent with previous QTL analyses of this population. Strengths and limitations of this methodology are presented, as well as means of improvement.
Botanical drugs: a new strategy for structure-based target prediction
Authors: Wei Xuxu , Wu Xiang , Cheng Zeyu , Wu Qingming , Cao Chen , Xu Xue , Shang Hongcai
Published: September 2021

Target identification of small molecules is an important and still changeling work in the area of drug discovery, especially for botanical drug development. Indistinct understanding of the relationships of ligand–protein interactions is one of the main obstacles for drug repurposing and identification of off-targets. In this study, we collected 9063 crystal structures of ligand-binding proteins released from January, 1995 to April, 2021 in PDB bank, and split the complexes into 5133 interaction pairs of ligand atoms and protein fragments (covalently linked three heavy atoms) with interatomic distance ≤5 Å. The interaction pairs were grouped into ligand atoms with the same SYBYL atom type surrounding each type of protein fragment, which were further clustered via Bayesian Gaussian Mixture Model (BGMM). Gaussian distributions with ligand atoms ≥20 were identified as significant interaction patterns. Reliability of the significant interaction patterns was validated by comparing the difference of number of significant interaction patterns between the docked poses with higher and lower similarity to the native crystal structures. Fifty-one candidate targets of brucine, strychnine and icajine involved in Semen Strychni (Mǎ Qián Zǐ) and eight candidate targets of astragaloside-IV, formononetin and calycosin-7-glucoside involved in Astragalus (Huáng Qí) were predicted by the significant interaction patterns, in combination with docking, which were consistent with the therapeutic effects of Semen Strychni and Astragalus for cancer and chronic pain. The new strategy in this study improves the accuracy of target identification for small molecules, which will facilitate discovery of botanical drugs.
A randomized clinical trial comparing early patient-reported pain after open anterior mesh repair versus totally extraperitoneal repair of inguinal hernia
Authors: Matikainen Markku , Vironen Jaana Hellevi , Silvasti Seppo , Ilves Imre , Kössi Jyrki , Kivivuori Antti , Paajanen Hannu
Published: September 2021

Background

This was a prospective, multicentre, non-blinded, randomized clinical trial involving two parallel groups of patients.

Methods

Adult patients with symptomatic unilateral primary inguinal hernia were included in this study. Patients were enrolled and treated in five Finnish hospitals. Eligible patients were randomized by use of a computer-based program to receiving either open anterior repair (modified Lichtenstein) with glue mesh fixation or totally extraperitoneal (TEP) repair. The primary aims were to compare 30-day patient-reported pain scores and return to work after surgery between the two groups.

Results

A total of 202 patients were randomized: 98 patients to TEP repair and 104 patients to open repair. All randomized patients received their allocated treatment. A total of 86 patients (88 per cent) in the TEP group and 94 patients (90 per cent) in the Lichtenstein group completed the 30-day follow-up. Patients experienced less early pain (P < 0.001) and used less analgesics after TEP repair, compared to those who had modified Lichtenstein repair. Two patients in the TEP group and five in the Lichtenstein group developed superficial wound infection (P = 0⋅446). Only one reoperation was performed in the Lichtenstein group due to haematoma.

Conclusion

TEP inguinal hernia repair is associated with less early postoperative pain compared to the open glue mesh fixation technique.

Trial registration

NCT03566433 (http://www.clinicaltrials.gov).