New Perspectives for LVL Manufacturing from Wood of Heterogeneous Quality—Part 2: Modeling and Manufacturing of Variable Stiffness Beams

This paper presents a new strategy in the use of wood of heterogeneous quality for composing LVL products. The idea is to consider veneers representative of the resource variability and retain local stiffness information to control panel manufacturing fully. The placement of veneers is also no longer random as in the first part of this group of papers but optimized for the quality of veneers according to the requirement of bending stresses along the beam. In a four-point bending test arrangement, this means the high-quality veneer is concentrated in the center of the beam in the area between the loading points where the bending moments are the most important, and the low quality is located at the extremities. This initiates the creation of variable stiffness beams. This is driven by an algorithm developed and tested on representative veneer samples from the resource. Four LVL panels were manufactured by positioning the veneers in the same positions as in an analytical calculation model, which allowed the calculation of beam mechanical properties in four-point bending. The proposed optimization of LVL manufacturing from variable quality veneers should help for more efficient usage of forest resources. This optimization strategy showed notable gains for modeled and experimental mechanical properties, whether in terms of stiffness or strength. The analytical calculation of the local modulus of elasticity from modelized beams was satisfactory compared to the tests of the manufactured beams test results, allowing the reliability of the model for this property to be confirmed.

New Perspectives for LVL Manufacturing from Wood of Heterogeneous Quality—Part. 1: Veneer Mechanical Grading Based on Online Local Wood Fiber Orientation Measurement

The grading of wood veneers according to their true mechanical potential is an important issue in the peeling industry. Unlike in the sawmilling industry, this activity does not currently estimate the local properties of production. The potential of the tracheid effect, which enables local fiber orientation measurement, has been widely documented for sawn products. A measuring instrument exploiting this technology and implemented on a peeling line was developed, enabling us to obtain the fiber orientation locally which, together with global density, allowed us to model the local elastic properties of each veneer. A sorting method using this data was developed and is presented here. It was applied to 286 veneers from several logs of French Douglas fir, and was compared to a widely used sorting method based on veneer appearance defects. The effectiveness of both grading approaches was quantified according to mechanical criteria. This study shows that the sorting method used (based on local fiber orientation and average density) allows for better theorical quality discrimination according to the mechanical potential. This article is the first in a series, with the overall aim of enhancing the use of heterogeneous wood veneers in the manufacturing of maximized-performance LVL by veneer grading and optimized positioning as well as material mechanical property modelization.

Sampling and its effect on the composition of archaeobotanical assemblages from the Roman Period

The subject of the presented study is taken from a dissertation project by one of the authors who focused on the processing of archaeobotanical assemblages from the Roman Period. The main aim of the research was the reconstruction of selected aspects of the subsistence strategy of the population in the given period based on the evaluation of archaeobotanical data from various chronological and cultural contexts in a designated region, available to author. The analysed sets were obtained during field excavations primarily conducted in the last third of the 20th century and the beginning of the 21st century. Uniform methods of archaeobotanical sampling were not applied in the acquisition of these assemblages. Source information on the origin of the samples was considerably heterogeneous and, in many cases, distinctly fragmentary. This was the impulse behind the investigation into the question as to whether, and to what extent, the method of sampling affects the interpretive value of the investigated dataset and what are the limitations of the analysis of such a dataset. The principal aim of this study is not the archaeobotanical evaluation of samples, but rather to investigate a possible effect of their formal properties on the composition of archaeobotanical finds. The formal properties studied include the volume and the number of collected samples, and the spatial stratification of samples (context/feature). Intuitively, it would appear that the heterogeneous quality of this information may have a certain impact on the interpretive value of an archaeobotanical assemblage. We discuss the effect of the chosen method of sampling on the composition of macro-remains in archaeobotanical samples and assemblages with the use of statistical models.

Quality Deviation Control for Aircraft Using Digital Twin

During the manufacturing process of aircraft, quality deviation problems inevitably occur due to the high complexity of aircraft design, manufacturing errors, tooling mistakes, human factors, environmental influences, design defects, and other factors. The current quality deviation control system of civil aircraft suffers from two problems: (1) quality deviation control data are scattered in more than 100 management systems, and it is difficult to extract quality data-related information from the whole life cycle of the aircraft involving the main manufacturer and each supplier and (2) there is a lack of quality data analysis and a closed-loop information-physics fusion system for quality deviation control. Thus, it is difficult to locate the quality deviation problems and it takes a long time to deal with these problems as well. In this paper, a digital twin-based quality deviation control model is proposed. Through the digital twin modeling based on asset management shell technology, the multi-source and heterogeneous quality deviation data can be extracted and integrated. Furthermore, to deal with the second problem, a quality deviation system has been built based on digital twin. In this system, the aircraft quality deviation data can be analyzed by the FP-growth association rule algorithm and the results are provided through the system to guide the assembly site, improving the efficiency and accuracy of quality problem-solving in the physical world. In addition, a case study is stated, where the proposed approach is applied to deal with the aircraft quality deviation problems.

Effects of Classroom Active Desks on Children and Adolescents’ Physical Activity, Sedentary Behavior, Academic Achievements and Overall Health: A Systematic Review

The purpose of this systematic review was to examine the effects of active desks in the school setting on sedentary behavior, physical activity, academic achievements and overall health among children and adolescents aged 5–17 years. A systematic literature search was conducted using five databases until October 2020. Twenty-three studies were included. Studies reported an increase of around 36% in energy expenditure for cycling desks and between 15% and 27.7% for upright active desks. Children increased inhibitory control and selective attention capacity while using cycling desks. A heterogeneous quality of design and of results were observed limiting comparisons and conclusions for each active desk. Despite the lack of strong methodology for the included studies, active desks appear to be a promising intervention in classrooms to improve health-related outcomes in children aged 5–17 years. Due to weak methodology, future studies with stronger study designs and methodology are needed to better inform policy and practice about the role of classroom active desks on health-related outcomes in children and adolescents.

ANALYSIS OF INHOMOGENEOUS ELECTROMECHANICAL SYSTEMS BASED ON A TOPOLOGICAL APPROACH

Stricter requirements for the efficiency and reliability of technical systems predetermine an in-depth study of electromechanical systems. The study involves taking into account the heterogeneity of their physical and vector space as operational factors that have a significant impact on the energy efficiency and reliability of the object. The proposed topological approach to the study of heterogeneous electromechanical systems (NEMS) is based on the analysis of their vector space. The multidimensionality, heterogeneity, and composite nature of the vector space are analyzed. Typical examples of the restrictions imposed on space vectors by the connection schemes of three-phase and multiphase NEMS windings are given. The main energy field is presented and the principle of the formation of the effective energy state of NEMS is formulated. Describes the tasks and method of implementing the operational diagnostics of NEMS based on the topological approach. In conditions of uncertainty, as well as heterogeneous quality, insufficient data, the feasibility of sharing the methods of fuzzy cognitive and logical analysis and modeling is substantiated. A cascade hybrid model is proposed, as well as methods for studying the vector space and operational diagnostics of NEMS based on it.

Patent Quality: Towards a Systematic Framework for Analysis and Measurement

The ‘quality’ of novel technological innovations is extremely variable, and the ability to measure innovation quality is essential to sensible, evidence-based policy. Patents, an often vital precursor to a commercialised innovation, share this heterogeneous quality distribution. A pertinent question then arises: How should we define and measure patent quality? Accepting that different stakeholders have different views of this concept, we take a multi-dimensional view of patent quality in this work. We first test the consistency of popular post-grant outcomes that are often used as patent quality measures. Finding these measures to be generally inconsistent, we then use a raft of patent indicators that are defined at the time of grant to dissect the characteristics associated with different post-grant outcomes. We find broad disagreement in the relative importance of individual characteristics between outcomes and, further, significant variation of the same across technologies within outcomes. We conclude that measurement of patent quality is highly sensitive to both stakeholder viewpoint and technology type. Our findings bear implications for scholarly research using patent data as well as for policy discussions about patent quality.

Bundlers' dilemmas in financial markets with sampling investors

We study banks' incentive to pool assets of heterogeneous quality when investors evaluate pools by extrapolating from limited sampling. Pooling assets of heterogeneous quality induces dispersion in investors' valuations without affecting their average. Prices are determined by market clearing assuming that investors can neither borrow nor short‐sell. A monopolistic bank has the incentive to create heterogeneous bundles only when investors have enough money. When the number of banks is sufficiently large, oligopolistic banks choose extremely heterogeneous bundles, even when investors have little money and even if this turns out to be collectively detrimental to the banks. If, in addition, banks can originate low quality assets, even at a cost, this collective inefficiency is exacerbated and pure welfare losses arise. Robustness to the presence of rational investors and to the possibility of short‐selling is discussed.