Bone Fractures Numerical Analysis in a Femur Affected by Osteogenesis Imperfecta

This work presents a non-invasive methodology to obtain a three-dimensional femur model of three-year-old infants affected with Osteogenesis Imperfecta (OI) type III. DICOM® Files of a femur were processed to obtain a finite element model to assess the transverse, the oblique, and the comminuted fractures. The model is evaluated under a normal walking cycle. The loads applied were considered the most critical force generated on the normal walking cycle, and the analyses considered anisotropic bone conditions. The outcome shows stress concentration areas in the central zone of the diaphysis of the femur, and the highest levels of stress occur in the case of the comminuted fracture, while the transverse fracture presents the lowest values. Thus, the method can be helpful for determining the bone fracture behavior of certain pathologies, such as osteogenesis imperfecta, osteopenia, and osteoporosis.

The Oxford Handbook of China Innovation

The Oxford Handbook of China Innovation provides a contemporary and authoritative view of the role of innovation in China’s extraordinary emergence. The Handbook consists of chapters written by over sixty experts from universities and research institutions worldwide, who describe and analyze this phenomenon with criticism, discussion of policy issues, and views about further development. It focuses on the microeconomic factors in China’s growth, of which the critical force has been the steady drive for innovation. It identifies the many factors instrumental in the development of innovation and evaluates those that are specific to China’s context, and those applicable to other nations. The scope of topics is comprehensive, covering China's development policies, the place of innovation in national priorities, the components of the national innovation system, and the resources required for their effective deployment. These include the institutions and policies that provide incentives and support to technological development, including people, financial mechanisms, private ownership, rule of law, and culture. The issue of foreign influence is also addressed, including the evolution of policy toward inward foreign direct investment and knowledge transfer and China’s goals for outward foreign direct investment. The chapters include discussion of the capabilities and strategies of world-class Chinese innovators, together with emerging issues such as environmental remediation, green energy, digital innovation, open innovation, mass innovation, and China’s future science and technology policy. As China emerges as a contender for global leadership in many fields, this Handbook provides a foundation for informed conjecture regarding the challenges ahead.

The Stability Analysis of Periodic Beams Interacting with Periodic Elastic Foundation with the Use of the Tolerance Averaging Technique

In this paper a stability analysis of microperiodic beams resting on the periodic inhomogeneous foundation is carried out. The main issue of this considerations, which is the analytical solution to the governing equations characterised by periodic, highly oscillating and non-continuous coefficients, is overwhelmed by the application of the tolerance averaging technique. As a result of such application, the governing equation is transformed into a form with constant coefficients which can be solved using well-known mathematical methods. In several calculation examples, the convergence of the results of two derived averaged models is examined, as well as the convergence of the lowest value of the critical force parameter derived from the averaged models with the FEM model. The results prove the superiority of the presented analytical solution over the FEM analysis in the optimisation process.

Stability Loss Analysis for Thin-Walled Shells with Elliptical Cross-Sectional Area

The aim of the scientific contribution is to point out the possibility of applicability of cylindrical shells with a constant elliptical cross-sectional shape for stability loss analysis. The solution to the problem consists of two approaches. The first approach is the experimental measurement of critical force levels, where the work also describes the method of production of the sample and jigs that cause the desired elliptical shape. The second approach is solving the problem in the use of numerical methods—the finite strip method together with the finite element method.

3D Printed Hollow Off-Axis Profiles Based on Carbon Fiber-Reinforced Polymers: Mechanical Testing and Finite Element Method Analysis

The aim of the paper is to design, manufacture, and test an off-axis composite profile of circular cross-section. Composite profile based on continuous carbon fibers reinforcing the onyx matrix, i.e., a matrix that consists of nylon and micro carbon fibers, was produced by fused deposition modeling (FDM) method. A buckling test of the six printed composite specimens was performed on a tensile test machine. The values of the experiment were compared with the values of the computational simulation using the Finite Element Method (FEM) analysis. The mean value of the experimentally determined critical force at which the composite profile failed was 3102 N, while the value of the critical force by FEM analysis was calculated to be 2879 N. Thus, reliability of the simulation to determine the critical force differed from the experimental procedure by only 7%. FEM analysis revealed that the primary failure of 3D printed composite parts was not due to loss of stability, but due to material failure. With great accuracy, the results of the comparison show that it is possible to predict the mechanical properties of 3D printed composite laminates on the basis of a theoretical model.

Using Paleoecological Data to Inform the Conservation Strategy for Floristic Diversity and Isoetes taiwanensis in Northern Taiwan

Paleoecological data can be used to inform nature conservation practice. Dream Lake (DL) is the best-preserved peat bog in the Tatun Volcanic Group of northern Taiwan. We analyzed continuous pollen and charcoal data from a well-dated sediment core from DL to reconstruct the changes in climate, lacustrine condition, and floristic diversity during the last 4500 cal BP. An absence of volcanic ash from all sediments indicates weak volcanic activity. Significant changes in lithology and pollen composition show that DL changed from a deep lake to a shallow peat bog from 3000 cal BP onwards. The palynological diversity index was negatively correlated with fire frequency. A substantial decline in Isoetes (quillwort) spores suggests increased vulnerability during the peat bog period. Natural terrestrialization will lower the mean water depth of DL below the minimum required for Isoetes taiwanensis survival within 300 years. Our findings indicate that winter precipitation driven by intense East Asian winter monsoons is the critical force determining the long-term variation in floristic diversity and abundance of I. taiwanensis. This long-term ecological history of DL, derived using paleoecological techniques, will be used to inform conservation practice in the Tatun Volcanic Group.

Tensile Buckling of a Rod with an End Moving along a Circular Guide: Improved Experimental Investigation Based on a Dynamic Approach

Investigation of buckling under tension is highly important from theoretical and practical viewpoints to ensure safety and the proper performance of mechanical systems. In the present work, tensile buckling is investigated experimentally, and the critical force is measured in systems where one end of an elastic tensile rod slides along a straight guide, while the other slides along a curve. An experimental setup is proposed and developed for determining the critical tensile load of the elastic rod by a dynamic method. This setup allows measuring free vibrations and frequency with the required accuracy. Improvement of the critical load accuracy is achieved by approaching the maximum load to the critical one. Limitations in selecting the test parameters are found according to the required extrapolation accuracy of the dominant natural vibration frequency dependence on tensile load. Theoretical analysis and tests are performed for the rod connection schemes pinned–rigid, rigid–pinned, and rigid–rigid, considering imperfections in the fixation of the rod ends. It is experimentally shown that the system buckling at tensile load is possible and that experimental and theoretical values of the critical load are in good agreement. The achieved accuracy, estimated by the discrepancy between the calculated and the experimental values, is 2.1–3.5%.

Kairos in Innovation Policy

A kairos constellation designates a temporarily existing opportunity for a group of actors to take advantage of a coincidence of favourable circumstances in order to realise a shared target. Starting from the observation that kairos constellations are ubiquitous in human individual and social life, the research question of this paper is how the Triple Helix and the wider innovation policy research literature deals with such constellations. The authors develop a conceptual framework for kairos constellations and discuss empirical evidence that kairos constellations have been scrutinized in innovation research literature. Then, the concept is applied to an example from the Triple Helix – based cluster policy. The key message of this paper is that Triple Helix researchers should systematically study kairos constellations because they are a critical force in the evolution of innovations systems as well as business firms, which has not yet been systematically examined.

Study of stability loss of cylindrical shell made of composite material

Introduction. Composite materials are used in the construction of transport infrastructure facilities, buildings and structures for various purposes, in housing and communal services. Calculation of structures made of composite materials is used in the field of stress-strain state, buckling, analysis of material under tension, the effect of cracks on the state of these structures. The main properties of composite materials and a method of manufacturing a cylindrical shell structure from a composite material are considered. The total number of winding options is calculated using the combinatorial method.Materials and methods. A composite cylindrical shell with a radius of R = 300 mm and a height of H = 600 mm was chosen as the object of research. The creation of a model of a cylindrical shell in a finite element analysis package is described. An axial compressive load acting on the shell with a force of F = 100 kN is specified. Determination of the critical force ratio.Results. The results of the analysis of the loss of stability of the cylindrical shell are obtained and the graphs of the dependence of the critical force on the options for laying the layers are presented. Depending on the magnitude of the critical force and the form of buckling, the most and least favorable options for laying layers in a composite material package have been determined.Discussion and conclusions. A conclusion is made of the dependence of the critical force on the combination of stacking layers in the composite.

Mechanical Efficiency Investigation of an Ankle-assisted Robot for Human Walking with a Backpack-Load

The purpose of this work is to investigate the efficiency of wearable assistive devices under different load-carried walking. We designed an experimental platform, with a lightweight ankle-assisted robot. Eight subjects were tested in three experimental conditions: free walk with load (FWL), power-off with load (POFL), and power-on with load (PONF) for different levels of force at a walking speed of 3.6 km/h. We recorded the metabolic expenditure and kinematics of the subjects under three levels of load-carried (10%, 20%, and 30% of body mass). We define the critical force, where at a certain load, the robot inputs a certain force to the human body, and with the assistance of this force, the positive effect of the robot on the human body exactly compensates for the negative effect. The critical forces from the fit of the assistive force and metabolic cost curves were 130 N, 160 N and 215 N at three different load levels. The intrinsic weight of our device increases mechanical work at the ankle as the load weight rises, with 2.08 J, 2.43 J and 2.73 J for one leg during a gait cycle. With weight bearing increasing, the ratio of the mechanical work input by the robot to the mechanical work output by the weight of the device decreases (from 0.904, to 0.717 and 0.513), verifying that the walking assistance efficiency of such devices decreases as the weight rises.