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Finite element analysis of tibio-femoral contact mechanics of a customised knee spacer

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Biosurface and Biotribology 2022年第2期8卷 121-128页

作者： alex c.t.choh Andy Yew Seng Jin Yeo Desmond Y.R.chong Shi-Lu chia Department of Orthopaedic Surgery Singapore General HospitalSingaporeSingapore Engineering cluster Singapore Institute of TechnologySingaporeSingapore

With one-third of patients having osteoarthritis predominantly in one compartment of the knee,unicompartmental knee spacers have been introduced as a less invasive alternative to total knee ***,patients with the knee spacer implanted were seen to have persistent pain,resulting in high revision rates.A static finite element model of the knee and its interaction with a knee spacer implant at full extension and 90°flexion was used to investigate the tibio-femoral contact mechanics of the knee joint after a knee spacer *** different knee spacer designs(contoured,flat and c-shaped)were modelled and prescribed with cobalt-chrome,ultra-high molecular polyethylene and polyurethane material *** results suggested that a softer spacer is generally preferred as this helps in the conformity of knee spacer to the condyle,effectively distributing the load subjected to the *** spacers that result in high stresses resulting from lower contact areas should be avoided.

关键词： biomechanics contact pressure finite element analysis knee spacer

conics on Barth-Bauer octics

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Science china Mathematics 2024年第7期67卷 1507-1524页

作者： alex Degtyarev Department of Mathematics Bilkent UniversityAnkara06800Turkey

We analyze the configurations of conics and lines on a special class of Kummer octic surfaces. In particular, we bound the number of conics by 176 and show that there is a unique surface with 176 conics, all irreducible: it admits a faithful action of one of the Mukai groups. therefore, we also discuss conics and lines on Mukai surfaces: we discover a double plane(ramified at a smooth sextic curve) that contains 8,910 smooth conics.

关键词： K3-surface octic surface Kummer surface conic Mukai group

Developing the new soil science——Advice for early-career soil scientists

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Pedosphere 2024年第1期34卷 3-4页

作者： alex McBRAtNEY Sydney Institute of Agriculture&School of Life and Environmental Sciences The University of SydneySydney NSW 2006Australia

confucius said,“to know what you know and what you do not know, that is true knowledge.”Hartemink (2006) edited a prescient book on the future of soil science, the contents of which are worthy of consideration today. Since then, there has been a growing emphasis on soil carbon, soil health, and soil security, as well as increased capability of technology related to machine leaning and soil sensing and *** KNOWLEDGE DIScOVERY cAtEGORISAtION Based on the above ancient aphorism attributed to confucius, the author writing in Hartemink (2006) classified soil knowledge and knowledge discovery into 4 categories. An updated version is given in Fig. 1.

关键词： soil measurement. leaning

Blast waveform tailoring using controlled venting in blast simulators and shock tubes

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Defence technology（防务技术） 2024年第7期37卷 14-26页

作者： Edward chern Jinn Gan alex Remennikov David Ritzel Faculty of Engineering and Information Sciences University of WollongongWollongongNSW2522Australia Dyn-FX consulting Ltd 19 Laird Ave NorthAmherstburgONN9V 2T5Canada

A critical challenge of any blast simulation facility is in producing the widest possible pressure-impulse range for matching against equivalent high-explosive *** tubes and blast simulators are often constrained with the lack of effective ways to control blast wave profiles and as a result have a limited performance *** wave shaping techniques employed in some facilities are reviewed but often necessitate extensive geometric modifications,inadvertently cause flow anomalies,and/or are only applicable under very specific *** paper investigates controlled venting as an expedient way for waveforms to be tuned without requiring extensive modifications to the driver or existing geometry and could be widely applied by existing and future blast simulation and shock tube *** use of controlled venting is demonstrated experimentally using the Advanced Blast Simulator(shock tube)at the Australian National Facility of Physical Blast Simulation and via numerical flow simulations with computational Fluid *** venting is determined as an effective method for mitigating the impact of re-reflected waves within the blast *** control method also allows for the adjustment of parameters such as tuning the peak overpressure,the positive phase duration,and modifying the magnitude of the negative phase and the secondary shock of the blast *** paper is concluded with an illustration of the potential expanded performance range of the Australian blast simulation facility when controlled venting for blast waveform tailoring as presented in this paper is applied.

关键词： Advanced blast simulator Shock wave propagation Far-field explosion Blast loads Blast waves computational fluid dynamics

No evidence of predator odor avoidance in a North American bird community

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Avian Research 2024年第1期15卷 133-138页

作者： Austin Dotta Batur Yaman alex Van Huynh Department of Biology DeSales University2755 Station AvenueCenter ValleyPAUSA

Recent advances in our understanding of avian chemical communication have highlighted the importance of olfaction in many aspects of avian *** studies investigating predator avoidance behaviors in response to predator odor cues have produced mixed results across species and *** we assess if a community of birds in eastern Pennsylvania displays avoidance behaviors towards predator odor cues in a natural foraging *** use clay caterpillars to measure foraging activity by birds in the presence of predator(bobcat)urine,non-predator(rabbit)urine,and water controls in two different environmental contexts(field ***).Although we detected a weak trend for birds to forage less at predator urine-treated sites,we found no significant difference in avian foraging between the site *** did find that foraging rates between environmental contexts changed significantly over the course of the experiment,with forest sites showing decreasing foraging rates and field sites showing increasing foraging *** results reinforce the published literature that avoidance of predator odors by birds may not be ubiquitous across contexts and species.

关键词： Foraging Odor Olfaction Predation Predator-avoidance

Kinematics ofmandibular advancement devices(MADs):Why do some MADs move the lower jaw backward duringmouth opening?

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Bio-Design and Manufacturing 2024年第5期7卷 637-650页

作者： Juan A.cabrera alex Bataller Sergio Postigo Marcos García Mechanical Engineering Department University of Malaga29071 MalagaSpain

Mandibular advancement devices(MADs)are widely used treatments for obstructive sleep *** function by advancing the lower jaw to open the upper *** increase patient comfort,most patients allow the mouth to be ***,not all systems maintain the lower jaw in a forward position during mouth opening,which results in the production of a retrusion that favors the collapse of the upper ***,the kinematic behavior of the mechanism formed by the mandible-device assembly depends on jaw *** means that,during mouth opening,some devices cause lower jaw protrusion in some patients,but cause its retraction in *** this study,we report the behavior of well-known devices currently on *** do so,we developed a kinematic model of the lower jawdevice *** validated for all devices analyzed using a high-resolution camera *** results show that some of the devices analyzed here did not produce the correct behavior during patient mouth opening.

关键词： Mandibular advancement devices Lower jaw kinematics Sleep apnea

Reinforcement Learning-Empowered Graph convolutional Network Framework for Data Integrity Attack Detection in cyber-Physical Systems

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cSEE Journal of Power and Energy Systems 2024年第2期10卷 797-806页

作者： Edeh Vincent Mehdi Korki Mehdi Seyedmahmoudian alex Stojcevski Saad Mekhilef School of Science Computingand Engineering TechnologiesSwinburne University of TechnologyMelbourneAustralia

the massive integration of communication and information technology with the large-scale power grid has enhanced the efficiency, safety, and economical operation of cyber-physical systems. However, the open and diversified communication environment of the smart grid is exposed to cyber-attacks. Data integrity attacks that can bypass conventional security techniques have been considered critical threats to the operation of the grid. current detection techniques cannot learn the dynamic and heterogeneous characteristics of the smart grid and are unable to deal with non-euclidean data types. to address the issue, we propose a novel Deep-Q-Network scheme empowered with a graph convolutional network (GcN) framework to detect data integrity attacks in cyber-physical systems. the simulation results show that the proposed framework is scalable and achieves higher detection accuracy, unlike other benchmark techniques.

关键词： Deep reinforcement learning graph convolutional network heterogeneous smart grid network

Sensing of membrane tensions:the pleiotropic functions of OScA/tMEM63 mechanosensitive ion channels

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Journal of Genetics and Genomics 2024年第6期51卷 579-582页

作者： Bo Yu alex costa Yang Zhao Shanghai center for Plant Stress Biology CAS Center for Excellence in Molecular Plant SciencesChinese Academy of SciencesShanghai 200032China Key Laboratory of Plant carbon capture Chinese Academy of SciencesShanghai 200032China University of chinese Academy of Sciences Beijing 100049China Department of Biosciences University of MilanVia Celoria 26Milan 20133Italy

Organisms sense and respond to environmental and developmental signals to drive adaptive responses(Kefauver et al.,2020;Yu et al.,2024).these stimuli can be mainly divided into physical and chemical stimuli,and the physical stimuli include light,temperature,sound,vibration,pressure,stretch,shear stress,osmotic stress,and substrate *** of these physical stimuli trigger physical forces and alter membrane tension,which in turn activates mechanosensitive channels(Mscs)and converts the mechanical cues into biochemical signals.

关键词： deformation. convert mec

A pressure-sensitive rheological origin of high friction angles of granular matter observed in NASA–MGM project

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chinese Physics B 2024年第6期33卷 559-567页

作者：程晓辉肖世泽杨森赵乃峰 alex Sixie cao Department of civil Engineering Tsinghua UniversityBeijing 100084China college of transportation Engineering Nanjing Tech UniversityNanjing 211816China Institute of Structural Engineering ETH ZurichZurich 8092Switzerland

An abnormally high peak friction angle of Ottawa sand was observed in(National Aeronautics and Space Administration) NASA–(Mechanics of Granular Materials) MGM tests in microgravity conditions on the space shuttle. Previous investigations have been unsuccessful in providing a constitutive insight into this behavior of granular materials under extremely low effective stress conditions. Here, a recently proposed unified constitutive model for transient rheological behavior of sand and other granular materials is adopted for the analytical assessment of high peak friction angles. For the first time, this long-eluded behavior of sand is attributed to a hidden rheological transition mechanism, that is not only rate-sensitive, but also pressure-sensitive. the NASA–MGM microgravity conditions show that shear-tests of sand can be performed under abnormally low confining stress conditions. the pressure-sensitive behavior of granular shearing that is previously ignored is studied based on the μ(I) rheology and its variations. comparisons between the model and the NASA microgravity tests demonstrate a high degree of agreement. the research is highly valid for pressure-sensitive and rate-dependent problems that occur during earthquakes, landslides, and space exploration.

关键词： granular matter microgravity pressure-sensitive NASA–MGM