bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of models and methods for creating a digital twin of plant within the cyber-physical system for precision farming management
Authors: Skobelev P O , Mayorov I V , Simonova E V , Goryanin O I , Zhilyaev A A , Tabachinskiy A S , Yalovenko V V
Published: February 2021

The paper discusses creation of a digital twin (DT) of plant for an intelligent cyber-physical system for managing precision farming. A new approach to formalization of DT knowledge is proposed to form expert knowledge within the subject area based on the ontological specification of stages of plant growth and development and multi-agent technology for creating stage agents and coordinated dynamic recalculation of stage duration and yield forecast based on events in the environment. The paper proposes a method for calculating the forecast for duration of plant development stages and yield based on expert knowledge. A “tube” model of the range of changes in parameters of plant development for each stage has been developed. The paper also introduces a method for calculating the yield forecast, as well as the dates of beginning and end for each plant development stage within the “tube” during their normal development and in case of critical situations, for example, frost or drought. Ontology of plant development is constructed for implementation of the “tube” model of environmental parameters, which is converted into a digital form within the ontology editor, available for use by agents. The paper describes the structure and functions of a smart plant DT, built on the basis of a knowledge base and a module for multi-agent planning of plant development stages (for example, wheat), integrated with external weather forecast and fact services. A brief description of the created prototype of the intelligent plant DT system in Java is given. Using the system, agronomists can create their own knowledge bases and DTs of the cultivated plants for each field or even field section. The system will be useful in modern crop production for precision farming, not only “place-wise” but also “time-wise”, i.e. in terms of the best time for performing agrotechnical operations.
Threats of information security in the application of GIS in the interests of the digital economy
Authors: Burlov V G , Gryzunov V V , Tatarnikova T M
Published: February 2021

The development of a digital economy is impossible without the use of geographic information systems (GIS). On the other hand, the use of GIS entails the implementation of new threats. The article analyses possible threats, the requirements of regulators, formulates the necessary and sufficient conditions for ensuring security when using GIS.
Conceptual modelling of public administration the innovation process in the context of digitalization with catch-up modernization
Authors: Sirota E N
Published: February 2021

The article is devoted to the conceptual modelling of state management of the innovation process in modern conditions. The construction of the conceptual model included the identification and operational description of the goals of state management of the innovation process, the definition of significant controlled inputs to this process from the state, as well as possible types and tools of control actions on them. The article substantiates the roles of the following key parameters of the state impact model on the innovation process: the national innovation resource, the institutional, legal, economic, socio-psychological conditions for its formation, and the state order for socially significant innovations. It is shown that the main and most effective control actions of the social state on the innovation process should be aimed at reducing the cost and providing wide access to modern forms of education at all levels based on digitalization and artificial intelligence. The author substantiates the need for a closer link between the formation of scientific and technological schools of the country and the specifics of its natural resource base, as well as the institutionalization of economic responsibility of experts with state funding of socially significant innovations. The presentation of this conceptual model can become a material for discussion, which will facilitate the transition from conceptual to numerical and simulation modelling of the process under consideration. The article was prepared based on the results of research carried out at the expense of budgetary funds on the state order of the Financial University
The approach to the development of a probabilistic model to determine the optimal mechanism for an unfinished oil well fund subsidising
Authors: Feshina S S , Nikolaev D A , Feshina Y O , Caruana E M
Published: February 2021

In the context of the coronavirus pandemic and quarantine measures taken by the international community, energy demand declined significantly in the second quarter of 2020. In April, oil prices fell to a record low of $13-$14 per barrel. In order to restore oil prices, OPEC+ imposed strict restrictions on production in May. This has in turn decreased the number of drilling wells significantly and has had a negative impact on oilfield service companies. The decline of the oilfield services can lead to a loss of skills in the development of hard-to-recover reserves and to a loss of global market share. In order to reduce risks and ensure accelerated recovery of production volumes, a number of countries are developing and introducing methods of state subsidising to stimulate the construction of oil wells up to the moment of their completion. In Russia, the Ministry of Industry and Trade is also developing a plan to provide preferential loans to oilfield service organisations, and then oil companies will redeem finished wells. Given the recession in the global economy, the high volatility of macro parameters, the risk of the second wave of coronavirus and the new OPEC+ restrictions, makes it necessary to determine the best and most sufficient, but not excessive, mechanism for supporting oilfield services and stimulating the optimal pace of construction of oil wells depending on the type of oil fields and their remoteness from world markets’ sales. In view of the high uncertainty of model parameters, this paper proposes to use probabilistic methods and Bayesian methods to solve the above problems.
Fuzzy material balance method to model hydrocarbon field development
Authors: Sidelnikov K A , Faizullin R V
Published: February 2021

This paper introduces a new approach for modeling material balance of fluid withdrawal during field development in case of uncertainties. The approach is based on representation of the fixed reservoir and fluid parameters by fuzzy numbers. The resulting membership function of reservoir pressure is obtained by using fuzzy number operations.
Active identification of object parameters with non-scalar inputs-outputs
Authors: Troshina G V , Voevoda А А
Published: February 2021

In this work, within the framework of the active identification problem, the recurrent least squares method is used to determine the object parameters with non-scalar signals at the input and output of the system. The proposed technique is shown using the example of a third order object. Calculations are executed in Simulink environment. Parameter estimates are received for a discrete description of a third-order object as a result of modeling in Simulink environment. Convergence graphs of parameter estimates to the base values of the in question object are given. It should be noted the rapid convergence of parameter estimates. A meander type signal was used to test the proposed parameter estimation algorithm.
Models and methods of decision-making and probabilistic methods in information processing as an applied tool for data evaluation
Authors: Zbrishchak S G , Zvyagin L S
Published: February 2021

Decision-making is a process that requires a lot of effort, sufficient knowledge, and making a choice by analyzing various solutions to many problems. The set of problems is called in another way the set of alternatives x. When solving the problem of decision-making in organizational models, in fact, we make a choice, giving preference to one or another option, based on characteristics and certain criteria. But first, you need to correctly form the initial alternatives, based solely on the conditions and limitations of external systems that affect the problem being solved. If the decision-maker (hereinafter referred to as the LPR) decides to ignore the requirements of external systems, the formed alternatives will not be complete enough, and the choice will be limited. As a result, it will not be possible to find the best solution among the presented ones. In General, it is accepted to consider the decision-making process as a system that consists of a certain set of typical stages and their actions that interact with each other. The number and stages of actions may vary, because the conditions and types of tasks are different. In turn, among all existing methods of data processing and analysis, mathematical methods of information processing are distinguished, which include statistical sequential analysis, the basis of which is probabilistic methods, which serve as one of the most effective analysis tools.
The possibility of using the potentiometric titration method to determine the antioxidant properties of wines
Authors: Solovyova L M , Grishin Y V , Kazak A N , Oleinikov N N , Chetyrbok P V
Published: February 2021

The results of study of phenolic composition, antioxidant activity and oxidation state of phenolic substances of white and red table wine materials were presented. Close correlational between the antioxidant activity of white table wine materials, the oxidation parameter of phenolic composition and the content of monomeric, oligomeric and polymeric forms of phenolic compounds were established., The correlation between antioxidant activity and oxidation parameter of phenolic substances has not been established for red wine materials. Direct effect of the oxidation state of phenolic substances in white table wine materials on their antioxidant activity was shown. The oxidation parameter of phenolic substances can be used as a criterion of assessing the antioxidant properties of white table wine materials and wines. The method of potentiometric titration may be recommended for use in processing, training and experimental analytical laboratories to assess the antioxidant activity of white table wine materials and wines.
Technological aspects of the trust in cross-border paperless exchange
Authors: Kustov V N , Silanteva E S
Published: February 2021

To operate high quality expert and decision support systems we need to use data that could be trusted. Given differences in technical, legal, and administrative environments, cross-border paperless exchange poses significant challenges to the data validation. These challenges could be overcome due to the provision of the trust to the technologies used to exchange data across borders. That is why this article discusses trust technologies that allow cross-border data exchange in electronic form. The article provides a brief description of advantages and disadvantages of the three main validation protocols: DVCS, XKMS, and OASIS DSS. As the main form to provide trust in cross-border documents exchange we propose trusted third party (TTP) technology. Hardware and software aspects of the TTP implementation in the form of hardware and software package are described in the article with the examples of successful implementation of cross–border electronic legally significant documents flow implementation.
Numerical analysis of a two-stage forming process for a hollow part with external flange
Authors: Winiarski G , Bulzak T , Szala M
Published: February 2021

This paper presents the results of a numerical analysis of a two-stage forging process for producing a hollow part with an external flange. The numerical analysis was performed via the finite element method using Deform-2D/3D. The analysed case included a cold forming process. The billet was a tube made of a low alloy steel grade 42CrMo4 with its flow curve described by a constitutive equation. The forming process involved the use of two operations: extrusion and forging in a tapered die cavity. The objective of the study was to determine whether the proposed forming technique could be used for production of hollow flanged parts. The kinematics of material flow, distributions of effective strains and the Cockcroft–Latham ductile fracture criterion, as well as force parameters were examined. The conducted research confirmed the correctness of the proposed method.
Evaluation of diagnostic accuracy of physical examination and MRI for ligament and meniscus injuries
Authors: Krakowski P , Karpiński R , Jonak J , Maciejewski R
Published: February 2021

Surgical planning shall be based on thorough physical examination and radiological findings during patient evaluation. The use of computational methods in the evaluation of diagnostic tests may facilitate the decision-making process as well as reduce treatment costs. Conventional X-ray is a modality of choice for bone visualisation however, it is not suitable for soft tissue evaluation. MRI is a tool designated for soft tissue examination however, its accuracy is debated in the literature. This study was performed to evaluate the diagnostic accuracy of MRI in most common knee injuries in comparison to physical examination. The evaluation of selected diagnostic methods used in the evaluation of ligaments and meniscus was carried out based on statistical indicators and ROC (Receiver Operating Characteristic) curves. The indicators were determined using Statistica and Matlab software. 69 patients were enrolled in the study, who were previously scheduled for arthroscopic knee surgery. Each patient underwent a closed protocol physical evaluation prior to surgery. MRI reports were collected and stored. Diagnostic accuracy was evaluated with the use of ROC curves. Physical examination presented greater diagnostic accuracy than MRI in ACL tears. The same dependency was found in lateral and medial meniscal tears. MRI showed AUC of 0.835 for MM, 0.788 for LM, and 0.870 for ACL, respectively. The physical examination had the greatest diagnostic accuracy in comparison with ACL tears, where AUC for the Lachman test reached 0,902. Apley test was most accurate for LM tears with AUC reaching 0,842, while the McMurray test was the most accurate for MM lesions. MRI is a preferable addition to a thorough physical examination.
Buckling numerical analysis of composite plate element in asymmetrical configuration
Authors: Falkowicz K
Published: February 2021

The work presents the original conception of a thin-walled plate element with the central rectangular cut-out for use as an elastic or load-bearing element, subjected to uniform compression. Plates were simply supported on shorter edges, made of composite with high strength properties. The analysis aimed to choose a laminate layer configuration that would ensure the lowest buckling form about bending-torsional character, ensuring stable construction work in the post-critical range. The influence of cut-out geometrical parameters and the angle of fibre layout on the value of the critical load of the structure was measured. To develop a discrete model and to perform numerical calculations the commercial ABAQUS program was used.
Finite element modelling of independent core propagation in multicore photonic crystal fibres resulting from anisotropy in structure
Authors: Mohammed M , Ahmad A K
Published: February 2021

COMSOL MULTIPHYSICS software based on the finite element method is being used to simulate the random anisotropy in diameters of the cores formed in multicore photonic crystal fibre structures, and this may affect the coupling properties between the cores’ modes. Consequently, this leads to a reduction in the coupling efficiency between the cores with different structures. This anisotropy in diameters of the cores leads to the creation of a small mismatch between the modes of these cores and is sufficient to inhibit coupling. The coupling properties are affected hugely depending on the amount of the change in core diameter and increasing the number of cores coupled inside the multicore structure. We also found an improvement in the coupling efficiency when increasing the number of cores within the structure of the multicore photonic crystal fibres; otherwise, the independent light propagation of each core inside the multicore structure, with/without a little penetration with other adjacent cores. As the coupling efficiency of seven-core coupled is better than three-core, and the latter may be better than two-core in which the cores appear decoupled and independent in their propagated for the adjacent other cores. It can be considered this study a novel characteristic of multiplexing-demultiplexing applications.
Use of multidimensional testing to evaluate the impacts of treated wastewater discharge on river water quality - Hotelling test case
Authors: Majerek D , Łagód G , Szeląg B , Sabba F
Published: February 2021

Water bodies often suffer from the discharge of nutrient loading from agricultural and urban areas that compromises the quality of water. This study presents the application of the Hotelling test to evaluate the impacts of treated wastewater, discharged from a municipal wastewater treatment plant (WWTP), on the quality of river water. The quality of water was described by different pollution indicators, including COD, BOD5, TSS, NH4-N, NO2-N, NO3-N, TKN, TN and TP. The water samples were collected at three different locations: 500 m above the discharge point, at the wastewater discharge point and 1000 m below the wastewater discharge point. The tests of single pollution indicator showed differences between the two locations. Specifically, the results show that each single comparison controlled type I error at 0.05, while the family-wise error rate for the tests of all marginal hypotheses was controlled at 0.37. Testing for single indicators separately may not reveal true multivariate differences. In order to overcome this limitation, a modified version of T2 Hotelling test was used with robust James-Stein type estimators of covariance matrix. Major differences in the overall water quality were observed mainly for the concentration of nitrogenous compounds and found to significantly influence the water quality of the receiving river.
Strength analysis of a propulsion shaft dedicated for the main rotor test bench
Authors: Skiba K , Raczyński R , Kliza R , Wendeker M
Published: February 2021

This article presents the strength analysis of various drive shaft concepts for the test stand for research of aircraft’s main rotors. The results of stress analysis for conceptual shaft models are presented. A technological solution was developed on the basis of the obtained results to meet the design requirements and reduce the impact of maximum stress to a minimum. The aim of the study was to develop a design solution for a propulsion shaft research allowing for the most optimal way of conducting the research installation from a stationary to a rotary system (data and power collector system).
Magnetic sorbents based on Kuzbass long-flame coal
Authors: Zykov I Yu , Dudnikova Yu N , Tsvetkov V E , Ivanov N N
Published: February 2021

The paper investigates the textural characteristics of carbon sorbents obtained from Kuzbass coal of the LF grade. The sorbents were obtained by activation using ferric chloride, pre-impregnating the coal with an iron III chloride solution at a FeCl3/coal ratio of 1:7 g/g. Powder X-ray diffraction in sorbents proved the presence of the Fe3O4 phase of magnetite. The amount of magnetite in the sorbents varies within 7%. It is shown that sorbents obtained from coal activated with iron chloride have a sufficiently developed porous structure and significant microporosity. The measured values of the specific surface area of sorbents at an activation temperature of 800 °C reach 250 m2/g, and at 700 °C they are an order of magnitude lower. The total pore volume does not exceed 0.1 cm3/g with a micropore fraction of more than 70%.
Bi-reforming of methane: thermodynamic equilibrium analysis and selection of preferable reaction conditions
Authors: Matus E V , Sukhova O B , Ismagilov I Z , Kerzhentsev M A , Li Lei , Ismagilov Z R
Published: February 2021

To determine the optimal reaction conditions of bi-reforming of methane thermodynamic analysis of reaction was performed. The effects of process variables, such as temperature (T = 500–1000°C), pressure (P = 1–30 atm), and feed composition CH4/CO2/H2O on the product distribution were studied. It was shown that to maximize the conversion of reagents and yield of target products the high reaction temperatures (T > 800°C) and atmospheric pressure should be applied. The reaction pathway of the bi-reforming of methane is affected by the feed composition. At 800°C the molar ratio of O/C ≥ 1.1 are preferable to work at region free of carbon formation. The CO2 conversion and H2/CO ratio are controlled by the value of CO2/H2O ratio. Depending on the field of application of synthesis gas, this ratio can be tuned from 1.2 to 2.8 through variation of CO2/H2O ratio from 3 to 0.1. The selected reaction conditions (T = 800°C, P = 1 atm, CH4/CO2/H2O = 1/0.8/0.4) were applied for bi-reforming reaction over Ni catalyst which provided the process parameters close to thermodynamic equilibrium results.
Sorption methods for capturing carbon dioxide by various sorbents
Authors: Nechaeva T S , Fedorova N I , Matus E V , Li Lei , Ismagilov Z R
Published: February 2021

The article discusses the main methods of capturing carbon dioxide used in the processes of cleaning flue gases. The paper presents some schemes for the extraction of CO2, shows their advantages and disadvantages. The adsorption method for extracting carbon dioxide with commercial sorbents and activated carbons obtained on a coal and plant basis is considered in detail. The characteristics and properties of the main solid sorbents are given. The main indicators of the quality of activated carbons, which affect the efficiency of the extracted gas, have been established. Methods of modification of activated carbons and their influence on the sorption of carbon dioxide have been studied. As a result of the analysis of literature data and taking into account the growth of world energy consumption, it was concluded that carbon dioxide capture is a promising area of scientific research.
New immunological markers for the identification of lung cancer risk groups among workers in hazardous industries in Kuzbass region
Authors: Ustinov V A , Nekrash M S , Studennikov A E , Glushkov A N
Published: February 2021

Polycyclic aromatic hydrocarbons are widely known as risk factor in relation to lung cancer development. In this connection, we suggested to use idiotypic and anti-idiotypic antibodies IgG and IgA classes against polycyclic aromatic hydrocarbons in human blood serum as new biomarkers for lung cancer risk. The blood serums of 202 healthy men and 275 men with lung cancer were analyzed by ELISA based on idiotypic and anti-idiotypic antibodies IgG and IgA classes against polycyclic aromatic hydrocarbons. Obtained data were analyzed. It was suggested to use ratio of idiotypic and anti-idiotypic antibodies rather than distinguish level each of them separately. The neural networks for idiotypic and anti-idiotypic antibodies of IgG class (AUC = 0.95), idiotypic and anti-idiotypic antibodies of IgA class (AUC = 0.86), and idiotypic and anti-idiotypic antibodies of IgA and IgG classes (AUC = 0.93) were built as models for lung cancer predictions. Finally, the ELISA data of 52 Kuzbass region coal miners were identified as a group of lung cancer risk using obtained models. So, suggested markers antibodies in human blood serum were not only identified lung cancer patients also elicited group of lung cancer risk among healthy people.
Considering the settling of dispersed water in the water barrier when calculating the explosion-proof distance at the methane explosion in a mine
Authors: Kusainov P I , Mazepa E E , Kraynov A Yu , Lukashov O Yu
Published: February 2021

Gas dynamics equations are used to simulate the interaction of shock waves with water or rock–dust barriers. The model is enhanced with the presence of dispersed water in the flow and its settling on the walls of the working. An approach to the implementation of the method for solving the problem of the propagation of shock waves in a branched network of mine workings, considering the interaction of shock waves with water barriers has been developed. The approach is based on the use of the numerical method of S.K. Godunov. Examples of solving the problem of the propagation of shock waves from a methane explosion in simulated networks of coal mine workings with water barriers placed in them are given.
Kuzbass in the context of strategic challenges: coal chemistry as a solution to economic problems
Authors: Kryukov V. A. , Fridman Yu.A. , Markova V. M. , Rechko N.G. , Loginova E. V.
Published: February 2021

The increase in coal production and export for Kuzbass cannot remain the only factor affecting economic growth in the future. Coal chemical cluster development is one of the ways to diversify regional economy which can not only contribute to monetization of coal resources and attraction of high-tech knowledge-intensive industries to the region but also improve domestic economic efficiency.
Soil-agrochemical analysis of the fertile soil layer from the Erunakovskiy field of the Taldinskiy coal mine
Authors: Yakovchenko M A , Izmulkina E A , Stenina N A , Ivina O A
Published: February 2021

Activity of mining enterprises lead to significant changes in the orography, composition and patterns of movement of groundwater, disruption of microbiota and impact on vegetation, which result in ecosystem destruction of vast land areas. The upper layer of the soil is subjected to serious changes due to physical impact during the extraction of minerals, thus it forms a technogenic relief. To restore the biological diversity of soils disturbed by surface and underground mining operations, a reclamation process is used, including the all typemanagement of physical, chemical and biological disturbances of the soil cover. Reclamation of abandoned mines’ territories is a very complex process. Vegetation restoration is the most widely recognized and practical way to reduce nitrogen losses and erosion, increase soil nutrients, and protect soils from degradation. Substantiation of the scaleto remove the fertile soil layer of mining operations is a compulsory condition for approving a plan of measures to restore theland quality. This work includes the study of the main properties of the potentially fertile soil layer of the Taldinskiy coal mine, Novokuznetsk district of the Kemerovo region of the Russian Federation, for the possibility of using it when carrying out work to restore its biological diversity.
The Kuzbass Basin coals as a raw material for the preparation of carbon quantum dots
Authors: Prazyan Tigran L , Dyagilev Denis V
Published: February 2021

The article discusses a promising method for producing carbon quantum dots (C-dots) from coal. Coal grades A (anthracite), K (coking), OS (lean-sintered) were used as raw materials. The separated particles were investigated by X-ray diffraction and optical methods of analysis. The interplanar distances in C-dots and the phase ratio in the samples are determined. The intrinsic absorption region was determined from the optical spectra and the band gap of the obtained C-dots was estimated. Lines of photoluminescence were found in the UV and visible ranges.
Quantitative photoacoustic estimates of intervascular blood oxygenation differences using linear unmixing
Authors: Bench C , Cox B
Published: February 2021

The linear unmixing technique is an appealing method for estimating blood oxygen saturation (sO2) from multiwavelength photoacoustic tomography images, as estimates can be acquired with a straightforward matrix inversion. However, the technique can only rarely provide accurate estimates in vivo, as it requires that the light fluence at the voxels of interest is constant with wavelength. One way to extend the set of cases where accurate information related to sO2 can be acquired with the technique is by taking the difference in sO2 estimates between vessels. Assuming images are perfectly reconstructed, the intervascular difference in sO2 estimates is accurate if the error in the estimates due to the wavelength dependence of the fluence is identical for both. An in silico study was performed to uncover what kinds of conditions may give rise to accurate sO2 differences for a vessel pair. Basic criteria were formulated in simple tissue models consisting of a pair of vessels immersed in two-layer skin models. To assess whether these criteria might still be valid in more realistic imaging scenarios, the sO2 difference was estimated for vessels in more complex tissue models.
Influence of Y2O3 particle size on the microstructure and corrosion behaviour of porous Si3N4 ceramics
Authors: Xu Z Y , Hai W X , Zhang X , Ma Y X , Ma W L
Published: February 2021

In this study, porous silicon nitride ceramics were fabricated by pressureless with different particle size of Y2O3 using as sintering additive. The effects of particle size of Y2O3 particles on sintering behaviour, microstructure and corrosion behaviour of the β-Si3N4 ceramics were studied in detail. As the Y2O3 particles size decreasing from 5 μm to 0.5 μm, the linear shrinkage of porous β-Si3N4 ceramics increased from 14.3% to 18.3%, and the sintering porosity decreased from 25.3% to 17.6%. The smaller Y2O3 particles additions were consisted of finer β-Si3N4 grains and demonstrated more accordant microstructure due to the well-dispersed Y2O3. The finer microstructure resulted in the improvement of mechanical properties, the sintered sample with 0.5 μm Y2O3 addition shown flexural strength of 450 MPa. Significant weight loss was observed after corrosion in 1 M HCl solution at 70°C for different time, due to the assumed formation of the grain boundary phase added to the Y2O3.
Study on self-assembly of novel hydrophilic silane containing PEG segments and its resistance to protein adsorption
Authors: Liu M G , Zhao R , Liu S Q
Published: February 2021

A new type of hydrophilic silane containing PEG (polyethylene glycol) segments was produced in this study. Membranes were produced through self-assembly. Hydrophilic silane was characterized by FTIR, 1H-NMR; The chemical composition and surface morphology of the self-assembled membrane surface were characterized by AFM, CA, SEM; The material’s resistance to protein adsorption was studied by UV-Vis and coomassie brilliant blue method [1]. The results showed that the novel hydrophilic silane containing PEG segments can be successfully assembled on silicon substrates; self-assembled membranes and blank silicon substrates in comparison, protein adsorption decreased from 274.8 μg/cm2 to 145.7 μg/cm2. This study has important reference significance for the preparation of anti-protein adsorption and bacterial adhension materials.
Shredding energy consumption of GFRP composite waste
Authors: Cheng S , Wong K H , Shen C P , Liu X L , Rudd C
Published: February 2021

This work investigated effect of glass fibre fabric structures, feedstock feed rate and screen size on specific shredding energy of glass fibre reinforced plastics (GFRP) waste via a two-level factorial design of experiment study. Four types of fabric structure, i.e. unidirectional (UD), biaxial (BIAX), triaxial (TRIAX) and chopped strand mat (CSM), were impregnated separately with unsaturated polyester resin to manufacture GFRP plates. The shredding energy was measured using a two-wattmeter approach. During shredding, CSM demonstrated a relatively flat power consumption curve compared to other fabric types. It was also noticed that the GFRP plate reinforced with more complex woven structure, i.e. TRIAX, required higher energy for shredding, especially with a combination of high feed rate and small screen size. It was found that mechanical efficiency was only around 8.2-15.7% and 0.8-2.2% for shredding at feed rate of 60 kg/hr and 10 kg/hr respectively. It was also found that adopting a larger screen size and lower feed rate could reduce the specific shredding energy.
Influence of chemical treatment on the recycling of composites before pyrolysis
Authors: Hao S Q , Wong K H , Liu X L , Rudd C D
Published: February 2021

Recycling of carbon fibers is one of the upcoming global research topics in composite engineering. This work investigates the influence of chemical treatment on the recovery of carbon fibers from carbon fiber reinforced plastic before pyrolysis. The chemical pretreatment was achieved using a zinc chloride/ethanol solution. The pyrolysis process was conducted in a sliding furnace. The effect of such pre-treatment on thermal degradation behaviour was determined by a thermogravimetric analyser (TGA). An original sample was also investigated for benchmarking. After the thermal pyrolysis process, the fiber tensile properties were measured using a single fiber tester. The surface functional groups and graphitization degree recovered carbon fiber were characterized using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The surface morphology of recycled carbon fibers was investigated by SEM. Pristine carbon fibers were also included in the study for benchmarking. During the pyrolysis process, the devolatilisation temperature of the pre-impregnated prepregreduced by around 40-50°C and the peak temperature was 40-50°C lower compared to that of the original prepreg. The chemical pre-treatment process reduces the pyrolysis temperature compared to the conventional pyrolysis process. After pyrolysis in nitrogen with a small amount of air, loose carbon fibers were recovered, and their surface was clean. The similar surface functional groups and the decrease of degree of graphitization were detected on the recycled carbon fiber.
WgLink: reconstructing whole-genome viral haplotypes using L0+L1-regularization
Authors: Cao Chen , Greenberg Matthew , Long Quan
Published: January 2021

Many tools can reconstruct viral sequences based on next-generation sequencing reads. Although existing tools effectively recover local regions, their accuracy suffers when reconstructing the whole viral genomes (strains). Moreover, they consume significant memory when the sequencing coverage is high or when the genome size is large. We present WgLink to meet this challenge. WgLink takes local reconstructions produced by other tools as input and patches the resulting segments together into coherent whole-genome strains. We accomplish this using an L0+L1-regularized regression, synthesizing variant allele frequency data with physical linkage between multiple variants spanning multiple regions simultaneously. WgLink achieves higher accuracy than existing tools both on simulated and on real datasets while using significantly less memory (RAM) and fewer CPU hours.

Availability and implementation

Source code and binaries are freely available at https://github.com/theLongLab/wglink.

Supplementary information

Supplementary data are available at Bioinformatics online.
Latent Cytomegalovirus Infection and Previous Capsular Polysaccharide Vaccination Predict Poor Vaccine Responses in Older Adults, Independent of Chronic Kidney Disease
Authors: Wall Nadezhda , Godlee Alexandra , Geh Daniel , Jones Charlotte , Faustini Sian , Harvey Ruth , Penn Rebecca , Chanouzas Dimitrios , Nightingale Peter , O’Shea Matthew , Richter Alex , Moss Paul , Cunningham Adam , Harper Lorraine
Published: January 2021

Background

Patients with chronic kidney disease (CKD) are more prone to severe infection. Vaccination is a key strategy to reduce this risk. Some studies suggest vaccine efficacy may be reduced in patients with CKD, despite preserved maintenance of long-term responses to some pathogens and vaccines. Here, we investigated immune responses to 2 vaccines in patients with CKD to identify predictors of immunological responsiveness.

Methods

Individuals >65 years old, with or without nondialysis CKD (n = 36 and 29, respectively), were vaccinated with a nonadjuvanted seasonal influenza vaccine (T-dependent) and Pneumovax23 (23-valent pneumococcal polysaccharide [PPV23], T-independent). Humoral responses were measured at baseline, day 28, and 6 months. Lymphocyte subset and plasma cell/blast analyses were performed using flow cytometry. Cytomegalovirus (CMV) serotyping was assessed by enzyme-linked immunosorbent assay.

Results

Only modest responsiveness was observed to both vaccines, independent of CKD status (25% adequate response in controls vs. 12%–18% in the CKD group). Unexpectedly, previous immunization with PPV23 (median 10-year interval) and CMV seropositivity were associated with poor PPV23 responsiveness in both study groups (P < .001 and .003, respectively; multivariable linear regression model). Patients with CKD displayed expanded circulating populations of T helper 2 and regulatory T cells, which were unrelated to vaccine responses. Despite fewer circulating B cells, patients with CKD were able to mount a similar day 7 plasma cell/blast response to controls.

Conclusion

Patients with nondialysis CKD can respond similarly to vaccines as age- and sex-matched healthy individuals. CKD patients display an immune signature that is independent of vaccine responsiveness. Prior PPV23 immunization and CMV infection may influence responsiveness to vaccination.

Clinical Trials Registration. NCT02535052
Bureaucrat Allocation in the Public Sector: Evidence from the World Bank
Authors: Limodio Nicola
Published: January 2021

The allocation of bureaucrats across tasks constitutes a pivotal instrument for achieving an organisation’s objectives. In this paper, I measure the performance of World Bank bureaucrats by combining the universe of task assignment with an evaluation of task outcome and bureaucrat CVs. I introduce two stylised facts. First, bureaucrat performance correlates with task features and individual characteristics. Second, there exists a negative assortative matching between high-performing bureaucrats and low-performing countries. In response to natural disasters, which may further weaken countries’ performance, I observe that low-performing countries receive an additional allocation of high-performing bureaucrats. I discuss various interpretations of these findings.
Robots and Firms
Authors: Koch Michael , Manuylov Ilya , Smolka Marcel
Published: January 2021

We study the microeconomic implications of robot adoption using a rich panel data set of Spanish manufacturing firms over a 27-year period (1990–2016). We provide causal evidence on two central questions: (1) Which firm characteristics prompt firms to adopt robots? (2) What is the impact of robots on adopting firms relative to non-adopting firms? To address these questions, we look at our data through the lens of recent attempts in the literature to formalise the implications of robot technology. As for the first question, we establish robust evidence for positive selection, i.e., ex ante better performing firms (measured through output and labour productivity) are more likely to adopt robots. On the other hand, conditional on size, ex ante more skill-intensive firms are less likely to do so. As for the second question, we find that robot adoption generates substantial output gains in the vicinity of 20–25% within four years, reduces the labour cost share by 5–7% points, and leads to net job creation at a rate of 10%. These results are robust to controlling for non-random selection into robot adoption through a difference-in-differences approach combined with a propensity score reweighting estimator. To further validate these results, we also offer structural estimates of total factor productivity (TFP) where robot technology enters the (endogenous) productivity process of firms. The results demonstrate a positive causal effect of robots on productivity as well as a complementarity between robots and exporting in boosting productivity.
Military Statecraft and the Use of Multinational Exercises in World Politics
Authors: Wolfley Kyle J
Published: January 2021

Although multinational military exercises have become a common foreign policy tool over the last three decades, our understanding of their purpose and variation is limited. Why do major powers conduct multinational exercises, especially with non-allies, and why did exercises increase after the end of the Cold War? I argue that a rise in strategic uncertainty—when adversaries and allies become less obvious—led major powers to increase their use of “shaping” exercises: training events designed not to threaten or prepare to use force, but to change the characteristics of or relationship between militaries. Textual sentiment analysis and regressions of over a thousand multinational exercises from 1980 to 2016 reveal that major powers reacted to an increase in strategic uncertainty by using these types of exercises to manage ambiguous threats and partners. This study highlights why and how major powers implement diverse tools of military statecraft—that is, the use of military organizations to achieve foreign policy goals—to reduce the threat of violent non-state actors and undermine one another in a competitive international system.
The Different Faces of Public Opinion: Is the American Voter Tinted by Mode?
Authors: Shino Enrijeta , Martinez Michael D
Published: February 2021

Declining response rates and increasing costs of collecting public opinion survey data have led to an increasing usage of dual-mode surveys. Revisiting foundational theories of political knowledge, issue constraint, and issue voting, we gauge the theoretical implications this methodological change has in our understanding of the public opinion and voter behavior. We see different patterns in the 2012 and 2016 American National Election Studies and observe clear mode effects in an original dual-mode survey experiment of Florida registered voters. Overall, we find that web respondents appear to be more politically knowledgeable, ideologically constrained, and have greater correspondence between issue and vote preferences compared to face-to-face or phone respondents. Survey mode matters, even with a common sampling frame.
Animal Models of COVID-19. I. Comparative Virology and Disease Pathogenesis
Authors: Zeiss Caroline J , Compton Susan , Veenhuis Rebecca Terilli
Published: January 2021

The Coronavirus Disease 2019 (COVID-19) pandemic has fueled unprecedented development of animal models to understand disease pathogenesis, test therapeutics, and support vaccine development. Models previously developed to study severe acute respiratory syndrome coronavirus (SARS-CoV) have been rapidly deployed to study SARS-CoV-2. However, it has become clear that despite the common use of ACE2 as a receptor for both viruses, the host range of the 2 viruses does not entirely overlap. Distinct ACE2-interacting residues within the receptor binding domain of SARS-CoV and SARS-CoV-2, as well as species differences in additional proteases needed for activation and internalization of the virus, are likely sources of host differences between the 2 viruses. Spontaneous models include rhesus and cynomolgus macaques, African Green monkeys, hamsters, and ferrets. Viral shedding and transmission studies are more frequently reported in spontaneous models. Mice can be infected with SARS-CoV; however, mouse and rat ACE2 does not support SARS-CoV-2 infection. Murine models for COVID-19 are induced through genetic adaptation of SARS-CoV-2, creation of chimeric SARS-CoV and SARS-CoV-2 viruses, use of human ACE2 knock-in and transgenic mice, and viral transfection of wild-type mice with human ACE2. Core aspects of COVID-19 are faithfully reproduced across species and model. These include the acute nature and predominantly respiratory source of viral shedding, acute transient and nonfatal disease with a largely pulmonary phenotype, similar short-term immune responses, and age-enhanced disease. Severity of disease and tissue involvement (particularly brain) in transgenic mice varies by promoter. To date, these models have provided a remarkably consistent template on which to test therapeutics, understand immune responses, and test vaccine approaches. The role of comorbidity in disease severity and the range of severe organ-specific pathology in humans remains to be accurately modeled.
Excess risk bounds in robust empirical risk minimization
Authors: Mathieu Timothée , Minsker Stanislav
Published: January 2021

This paper investigates robust versions of the general empirical risk minimization algorithm, one of the core techniques underlying modern statistical methods. Success of the empirical risk minimization is based on the fact that for a ‘well-behaved’ stochastic process $\left \{ f(X), \ f\in \mathscr F\right \}$ indexed by a class of functions $f\in \mathscr F$, averages $\frac{1}{N}\sum _{j=1}^N f(X_j)$ evaluated over a sample $X_1,\ldots ,X_N$ of i.i.d. copies of $X$ provide good approximation to the expectations $\mathbb E f(X)$, uniformly over large classes $f\in \mathscr F$. However, this might no longer be true if the marginal distributions of the process are heavy tailed or if the sample contains outliers. We propose a version of empirical risk minimization based on the idea of replacing sample averages by robust proxies of the expectations and obtain high-confidence bounds for the excess risk of resulting estimators. In particular, we show that the excess risk of robust estimators can converge to $0$ at fast rates with respect to the sample size $N$, referring to the rates faster than $N^{-1/2}$. We discuss implications of the main results to the linear and logistic regression problems and evaluate the numerical performance of proposed methods on simulated and real data.
Uncertainty principle for communication compression in distributed and federated learning and the search for an optimal compressor
Authors: Safaryan Mher , Shulgin Egor , Richtárik Peter
Published: January 2021

In order to mitigate the high communication cost in distributed and federated learning, various vector compression schemes, such as quantization, sparsification and dithering, have become very popular. In designing a compression method, one aims to communicate as few bits as possible, which minimizes the cost per communication round, while at the same time attempting to impart as little distortion (variance) to the communicated messages as possible, which minimizes the adverse effect of the compression on the overall number of communication rounds. However, intuitively, these two goals are fundamentally in conflict: the more compression we allow, the more distorted the messages become. We formalize this intuition and prove an uncertainty principle for randomized compression operators, thus quantifying this limitation mathematically, and effectively providing asymptotically tight lower bounds on what might be achievable with communication compression. Motivated by these developments, we call for the search for the optimal compression operator. In an attempt to take a first step in this direction, we consider an unbiased compression method inspired by the Kashin representation of vectors, which we call Kashin compression (KC). In contrast to all previously proposed compression mechanisms, KC enjoys a dimension independent variance bound for which we derive an explicit formula even in the regime when only a few bits need to be communicate per each vector entry.