bluuebunny/crossref_metadata_2025 huggingface dataset:
Algorithm Research on Manufacturing Agglomeration under the Background of Regional Integration Based on GMM Model
Authors: Lu Qiyuan
Published: August 2021

With the development of the process of regional integration, the manufacturing industry is also changing. This has attracted more attention. However, in the background of regional integration, there are relatively few empirical studies investigating the degree of manufacturing agglomeration. This paper selects nine cities in the Pearl River Delta, Guangdong Province, China from 2007 to 2017 as our sample. We use the Difference GMM Model to explore the impact of government support and labor concentration on manufacturing agglomeration. The measurement results show that both government support and labor concentration have a positive correlation with the degree of manufacturing agglomeration. Government support and labor concentration have different significance levels and coefficients for manufacturing agglomeration. In order to promote the increase in the agglomeration of the urban manufacturing industry, the increase in labor concentration will be more effective than government support.
Research on Object Detection Algorithm Based on Deep Learning
Authors: Li Meian , Zhu Haojie , Chen Hao , Xue Lixia , Gao Tian
Published: August 2021

The current target detection models have the characteristics of large storage, large demand for computing resources and large number of parameters, which are difficult to be implemented on the platform with low computing performance and small storage capacity. In order to reduce the size of the model and improve the detection speed, this paper proposes a new network architecture of mobilenetv2-yolov5s by combining the lightweight network mobilenetv2 with yolov5s Compared with other target detection algorithms, the improved yolov5s has better detection effect. The mobilenetv2-yolov5s network is tested on MS coco data set, and the mAP value is 55.1. While ensuring the map, the detection speed of the algorithm is 31fps, which is 25fps higher than yolov5s.
A Compilation Options with Optimization Techniques for IoT Network Systems
Authors: Cho Doosan
Published: August 2021

A compiler provides a variety of optimization options for execution speed, program size and energy consumption. Optimization options are provided by an optimizing compiler that supports hundreds of optimization techniques. In IoT network devices, it is difficult to apply an appropriate optimization technique required in specifications, because there are too many compilation options without detailed information about these options. In this study, we study various optimization techniques that can be applied by the compiler, and examine whether there is a side effect between the optimization techniques. Because optimization techniques are a series of tasks that change program code, side effect can be exist between the optimization techniques. As a result, certain optimization techniques can yield damage to the result of other techniques. To the best of our knowledge, there are few research on the side effect between various optimization techniques for IoT network devices, this study provides information that helps scheduling the optimization techniques.
Blade Profile Design and Optimization of Ocean Energy Low-speed Water Turbine
Authors: Lan Fuchuan , Liu Jiani , Zhang Fuxi , Wang Shiming , Chi Rong
Published: August 2021

Based on multi-objective genetic algorithm, naca4415 airfoil (NACA airfoil is a series of airfoils developed by the National Aeronautical Advisory Committee of the United States) is used as the original airfoil to optimize the blade airfoil of low water speed tidal current turbine, The lift drag ratio of the generator airfoil is improved (lift drag parameter is one of the key factors to determine the low-speed water kinetic energy conversion efficiency of the airfoil), the power generation efficiency of the turbine airfoil is improved, and the s airfoil is spliced on the basis of the optimized airfoil. The results show that the lift drag ratio performance of the optimized airfoil at the designed angle of attack is improved compared with that of the unoptimized airfoil, and the lifting range increases with the increase of the angle of attack. The pressure coefficient of the optimized airfoil decreases and the flow velocity increases. The pressure coefficient of the assembled S-shaped airfoil and the S-shaped airfoil have good bi-directional energy harvesting performance at the optimal attack angle of 12° to 15 °
The High-Order Perturbation Approximate Solution of the Finite Ultrasonic Wave
Authors: Zhang Shigong , Zhang Kesheng , Su Xiangdong
Published: August 2021

To the nonlinear acoustic wave equation, the general used second harmonic solution is not accurate enough because all perturbated expansion equations higher than the second order are ignored during the equation solving process. The purpose of this paper is to obtain a more accurate solution, i.e., the high-order perturbation approximate solution. Firstly, the nonlinear acoustic wave equation is expanded into many inhomogeneous partial differential equations. the low-order harmonic solutions are obtained manually, then we formulate the form of the high-order harmonic solutions according to the properties of the low-order harmonic solutions. Using symbol calculation tool, we finally obtained higher up to the 14th order perturbation special solutions. Odd order solutions contain only odd order harmonics, and even order solutions contain only even order harmonics. The high-order perturbation solution of the second harmonic is finally achieved by summing up all of the second harmonic solution parts. The simulation results show that the relative amplitude (A
2/A
1) of the second harmonic increases and then decreases with the propagation distance, which is in agreement with experimental results. The high-order perturbation approximated solution can compensate for the theory deficiency and can be used to measure the nonlinear parameter with a good precision.
Morphological Group Theory of Soft Matter Structure - A New Mathematics of Natural Image Numbers
Authors: Zhou Ziqiang
Published: August 2021

The accurate understanding and interpretation of the SARS-CoV-2 electron microscope photos (EMP) is of great significance for the scientific treatment of coronary pneumonia and precise strategy. Here I study the image mathematics and physics description of micro-images of soft matter system by the morphology group theory of material structure, and show that there is a natural image numbers equation, which can be used to describe not only the common feature of soft matter structure, but also to correct classify the states into different classes, so that to study the morphology physics for soft matter science and biology, some important basic concepts of biophysics, such as the central dogma of molecular biology, Gene sequence analysis, heuristic recognition of SARS-CoV-2 can also be newly explained and understood by the equation.
Advanced container inspection system based on dual-angle X-ray imaging method
Authors: Lim C.H. , Lee J. , Choi Y. , Park J.W. , Kim H.K.
Published: August 2021

In 2007, the U.S. Congress mandated the implementation of the “Security and Accountability For Every Port Act of 2006,” which requires complete scanning of 100% of U.S.-bound shipping containers. To address this requirement, we developed a container inspection method that enables continuous high-speed screening, with considerable performance improvement. In this study, we developed a fixed-type high-precision container inspection system using dual-angle X-ray beams from a 9 MV linear accelerator (LINAC). We first calculated the X-ray irradiation angle-dependent changes in the contrast-to-noise ratio (CNR) of the images via Monte Carlo simulation. Using the calculated CNRs, the primary and secondary angles of the X-ray beam were set to 0° and 2.8°, respectively. A system based on the proposed dual-angle X-ray imaging technology was installed and evaluated by scanning a real cargo container truck. For the evaluation, we designed test equipment based on the ANSI N42.46 report and examined the beam penetration power, contrast sensitivity, spatial resolution, and wire detectability of the developed system. The maximum penetration thicknesses for the primary and secondary angle beams were found to be 410 and 400 mm, respectively. At the primary beam angle, the contrast sensitivities were 1.52% and 0.49% when the thicknesses of the steel plate were 80% and 50% of the maximum penetration thickness, respectively. At the secondary angle, the sensitivities were 1.88% at 80% maximum penetration thickness, and 0.5% at 50%. A line pattern formed by individual slits of 4.6 mm width could be easily recognized in an acquired image. In addition, the developed system could clearly identify a 1.6 mm diameter copper wire. Further, when a steel plate was added, the change in the wire-recognition ability of the imaging system was found to be similar at both beam angles. These results indicate that the developed system is suitable for container screening using a 9 MV LINAC. Shapes that could not be identified from one beam irradiation angle could more accurately be analyzed using images from two different angles.
Characteristics of bituminous shales used in asphalt mixtures
Authors: Hanganu D-Dr
Published: August 2021

Bituminous shales, bitumolites or pyrosists are sedimentary rocks impregnated with an insolvent bitumen. In Romania, studies have been carried out on bituminous shales by almost all Romanian geologists, starting with Cobâlcescu in 1877, continuing with Mrazec in 1907, Athanasiu in 1926, Popescu-Voiteşti in 1943, etc. In 1956, Nicolae Grigoraş was the one who made the first studies in detail on bituminous shales. Considering that the only norm on the basis of which the technological recipes for asphalt mixtures with bituminous sand are made, it underwent the last modifications in 1985, one of the specific objectives of the research was to update the technical specifications contained in the regulations in order to streamline the technological process associated with these mixtures and for a better implementation at national level of these practices. Without this long-awaited review, the use of this unconventional material would become more difficult, although it has both technical, economic and environmental benefits.
High-early strength concretes modified with polycarboxylate admixture on different cement types
Authors: Kryzhanovskyi V , Kroviakov S , Zavoloka M
Published: August 2021

Early and grade strength of modified concrete on different cement types (CEM II/A-S 42,5 and pozzolanic cement CEM IV/A(P) 42,5 R-SR) for concrete pavements repair was explored. Application range of the polycarboxylate modifier was 0.8-1.4% by weight of cement. All concrete compositions had equal workability (slump 5…9 cm). The aim of the investigation was to determine the optimal volume of the polycarboxylate modifier to achieve high strength indicators for repair material at the early and grade age.

High-strength concrete of grades C 50/60 and C 40/50 were obtained, with early strength at the 3 days age above 35 MPa, which allows them to be used as a repair concrete material for rigid road pavements.

X-ray phase analysis confirmed the positive effect of the polycarboxylate admixture in the structure formation of concrete. With an increase in the dosage of the BASF MasterGlenium SKY 608 admixture to 1.2…1.4%, the intensity of the diffractogram lines, which corresponds to the metastable hydration phase in the cement-sand matrix, decreased for concretes on both cement types.
Experimental and finite element modelling of prestressed hollow-core slabs
Authors: Moldovan I F , Nedelcu M , Heghes B , Constantinescu H , Buru S M
Published: August 2021

This paper presents the results of a study conducted on prestressed hollow-core slabs (HCS), both experimentally and numerically. The research has been carried out on real scale HCS manufactured at a local precast factory. The concrete specimens were prestressed using ten 12.9 mm diameter steel tendons placed both at the bottom and the top flange of the cross-section. They were tested under concentrated load until shear failure. Validation of the numerical results undertaken using ABAQUS 6.13 software demonstrated that the values obtained from the numerical simulation match the experimental ones in terms of force-displacement relationship.
FEM analyses on beam-to-column connection for a thin-walled cold-formed steel frame
Authors: Venghiac V M , Olteanu-Donțov I , Alexa-Stratulat M S , Țăranu G , Băetu S A , Toma I O
Published: August 2021

The advantage of fast construction for thin-walled cold-formed steel ground floor structures is somehow lessened by the challenges the engineers encounter when designing the connections. The horizontal forces induced by the seismic motions and not only, represent a serious threat to flexible structures. The paper presents the results obtained from comparative FEM analyses of different types and layouts of beam-to-column connection in case of a thin-walled cold-formed steel frame. The obtained results were analysed and compared from the point of view of maximum vertical displacements of the beam free end, the load-displacement diagrams as well as the principal stresses. The objective was to obtain the most efficient type of connection that ensures the safe transfer of internal forces from the beam to the column.
Seismic response of 1/2 scaled two storey reinforced concrete moment resisting frame system using nonlinear static analysis
Authors: Sococol I , Olteanu-Donțov I , Mihai P , Iftode V-I
Published: August 2021

Reinforced concrete (RC) frame systems represent one of the structural solutions used in seismic zones by engineers. For this reason, the importance of knowing the real seismic response for these types of structures is essential and presents the research problem studied in this article. Thus, the seismic response for two storey axial RC frame (one bay-one span) system was studied using nonlinear static analysis in ATENA software. The structural degradation of the two storey RC frame system was investigated for several steel reinforcement possibilities and three distinct RC beams cross sections. Particular attention was paid to RC beam-column joints degradation areas and to seismic energy dissipation mechanism in the marginal regions of the RC columns. Thus, it was observed a nonlinear inelastic response in the potential degradation zones with contrary effects with respect to the specified conclusions in the current seismic design norms. Also, it was studied the RC slab bending stiffness influence to horizontal structural elements (RC beams) and to vertical structural elements (RC columns) alongside the cracking mode for horizontal static actions and RC slab local degradation beside RC beam-column joint area. In these conditions, conclusions regarding the seismic response of the moment resisting (MR) RC frame system with low height regime designed according to the current seismic code were specified and an unsatisfactory seismic response was proved.
Numerical flexural strengthening investigation of timber-CFRP composite beams
Authors: Harrach D , Movahedi Rad M
Published: August 2021

Timber is among the most important construction materials with unique characteristics in comparison with other materials for instance steel and concrete. It is one of the first sustainable materials and continues to be a favoured selection in the current infrastructure. In the last decade, to refine the mechanical properties of timber, structural elements reinforcing fiber polymers have developed. In this study, to improve the flexural properties of timber beams, carbon fiber-reinforced polymer (CFRP) laminates are attached externally and internally between timber layers. For numerical simulations, first finite element model was validated according to the data obtained from experimental tests, then a series of simulations with different parameters were executed to investigate the flexural behaviour. The considered parameters include CFRP laminates’ existence and position. The linear elastic orthotropic material model was used to represent linear behaviour while the 3D anisotropic Hill material model was assumed to define the nonlinear behaviour of the material. Finite element simulations are executed by commercial software ABAQUS.
The socio-economic efficiency of computer-integrated transport modelling
Authors: Rakytska S , Kambur O , Zhus O
Published: August 2021

In the article has been analysed the possibilities of using modern digital technologies to optimize the transport system of a big city. The Urbanization’s processes lead to high rates of urban development, which provides for the creation of assorted transport supplying. However, there are situations when the geographic, landscape, natural and climatic area features, architectural solutions (characteristics) or blunders in the design of the city do not allow to create the road infrastructure of the necessary level. This leads to congestion of the main transport networks and generate traffic jams, increasing the degree of environmental pollution. The authors consider the horizons of creating a transport model of the Odessa city as an effective method of traffic management. It has been made out a case that the digitalization of the urban highways management reduces the trip time, alleviates the level of the road network congestion, increases the reliability and safety of transport, minimizes the number of non-standard traffic situations, and increases the economic efficiency of the city’s transport system. The using of powerful content solution allows you to build a mental (virtual) model, taking into account the actual traffic situation at this time and predict its changing when you have to make a certain management decision. This article is dedicated to the economic issue of the building a city transport model, the contemplation for its use to improve the efficiency of the city economy operation.
An analytical design approach for post-tensioned concrete slabs with unguided tendons
Authors: Toader T-N , Kiss Z , Țere S-G , Puskás A
Published: August 2021

This article contains practical information on the design and dimensioning of prestressed concrete solid flat slabs using unbonded post-tensioned tendons, in accordance with the European standard EN 1992-1-1 and German standard DIN 1045-1. The calculation method and the mathematical equations necessary for the dimensioning of the non-adherent unguided tendons are given. The paper presents a case study where a slab floor is dimensioned for deflection using prestressing only in the column strips. The deflection of the slab is calculated using equivalent loads (unguided tendon), a mixt tendon profile with 4th degree curve segments (unguided tendon) and parabolic tendon profile with 2nd degree curve segments (guided tendon-classical solution).
Seismic response of setback buildings with multiple underground levels
Authors: Gafincu C V , Mihai P , Lungu I
Published: August 2021

The topic of this paper exceeds the provisions of the present regulations concerning the structural design issues related to the connection or the behaviour of the setback buildings on slopped ground surface. Setback buildings means that the spans progress in a step-like succession from one side of the building along the entire length. Due to the increased number of buildings positioned on sloping ground this paper aims to highlight aspects related to the influence of a variable number of underground levels. This research follows the differences between the loading effects acting on three types of setback buildings that differ by the number of the underground levels (one, two, respectively three), on the length of two spans. The conclusions of the paper refer to the influence of the number of underground levels on the seismic response of reinforced concrete structural elements: columns, beams and walls. The obtained results are compared in the form of internal forces: axial force, shear force and bending moment. The structural modelling and analysis of the buildings have been performed by using ETABS software. In the end these results will show the influence of the number of underground levels in the alteration of the structural elements above ground in terms of material consumption.
Effects of chemical degradation on longitudinal fracture of non-homogeneous beams: an analytical study
Authors: Rizov V
Published: August 2021

An analytical study of the chemical degradation of the material and its effects of on longitudinal fracture behaviour of continuously non-homogeneous cantilever beam is carried-out. The chemical degradation is described by decreasing of the elasticity modulus of the non-homogeneous material with time. The fracture is studied by analyzing of the strain energy release rate. For this purpose, the strain energy release rate is derived as a function of time with taking into account the chemical degradation and the non-homogeneity of the material. The time-dependent fracture is analyzed also by applying the J-integral with considering the chemical degradation for verification. The variation of the strain energy release rate with the time due to the chemical degradation is studied and discussed in detail.
Delamination analysis of multilayered viscoelastic beam exposed to chemical degradation
Authors: Rizov V
Published: August 2021

Delamination of multilayered viscoelastic non-homogeneous beam structure subjected to chemical degradation is analysed in this paper. The creep behaviour is treated by using a linear viscoelastic model. The influence of chemical degradation is taken into account by decreasing the elasticity modulus and the coefficient of viscosity with time. The time-dependent delamination fracture under chemical degradation is studied by analysing the strain energy release rate. The strain energy is used to obtain the strain energy release rate that accounts for the creep and for the chemical degradation. The solution is verified by applying the compliance method with considering of the chemical degradation.
Numerical modelling of point thermal bridge’s impact on the thermal performance of facade systems
Authors: Moga L , Moga I
Published: August 2021

Starting with 31 December 2020 all new buildings, as well as existing ones, must comply with the nearly Zero Energy Buildings levels, as defined by each member state. A very important design criteria is the one regarding an accurate assessment of both linear and point thermal bridges of the building envelope. Usually, point thermal bridges are either not considered in calculations or are assessed by using simplified methodology as described by the standard EN ISO 6946/2017. This is due to the modelling and calculation complexity required in assessing them. Therefore, in several situations the impact is underestimated, and the thermal performance results do not offer a clear image of the building’s thermal performance. Thus, the paper focuses on the modelling and simulation of several constructive solutions for façade systems, aiming to identify a correlation between the geometrical and thermal characteristics of fixing components and the thermal performance of the facade. The studied case scenarios include two types of masonry walls, of 240 and 365 mm, that are thermally insulated in various thicknesses using an ETICS system. A sensitivity analysis is also performed to define a correlation between all the components that define the system and the point thermal bridge impact magnitude. The results of the study indicate an increased impact with a direct consequence on the energy performance of the building.
Computation and experimental considerations on dynamic testing of cement mortar
Authors: Alexa-Stratulat S M , Covatariu D , Toma I O , Covatariu G
Published: August 2021

Non-destructive tests to assess the dynamic characteristics of the materials are important for both in-situ and laboratory situations. Elastic modulus, rigidity modulus and Poisson ratio can be determined through dynamic testing, by employing resonant frequency measurements. The ASTM C-215 standard contains the necessary information for the experimental set-up and subsequent computation using the longitudinal, transversal and torsional frequencies, for both prismatic and cylindrical specimens. Nevertheless, some experimental particularities are not explained and their influence on the final results might prove important. In this paper, the experimental and computational insights on performing the dynamic Young modulus test for cement mortar prismatic samples, with emphasis on the importance of interpretation of the results are presented. The type of specimen support and the actual data manipulation, when extracting results, are taken into consideration. The results may prove important for the correct employment of dynamic testing.
Database assessment of the reinforced concrete water tanks built fund in Iasi county
Authors: Covatariu D , Filip A , Covatariu G , Toma I O
Published: August 2021

Reinforced concrete water tanks are special structures and important from a strategically point of view. In particular, they are degraded both at the exterior (aggressive environmental agents) and interior (chlorinated water). A case study based on a group of water tanks (over-ground, semi-buried, underground) which have been investigated / analysed in the period 2016-2020 was conducted based on the degradations / non-conformities identified (on site visits, in monitoring / technical expertise reports, etc.). In this regard, for each constructive type (also considering the exploitation period and storage capacity), certain types of degradations were identified. Taking into account the state of degradation of each objective studied / analysed, a scoring system was assigned. The aim of this article is to conceive an algorithm (following the analysis of the database) regarding the level of degradations for each constructive system and to propose the suitable rehabilitation procedures corresponding to the investigated water tanks.
Indirect determination of the measurement accuracy of the FMK-004 track geometry measuring car used on Hungarian rail network
Authors: Nagy R , Horvát F
Published: August 2021

During the examination of the Hungarian national network for the period from the 2nd half of 1999 to the 2nd half of 2013, had to answer to the reason why the geometrical errors are able to decrease, despite the fact that no regulation intervention was done on the line section during the study period. This anomaly leads us to the procedure in which it became important to determine the accuracy of the FMK-004 measuring car (FMK in English: railway superstructure measuring car). With the VBA code written for the research task, the data set was optimized, then deterioration functions were fitted to the data, and where outliers were detected, the extent of the outlier was analysed on a statistical basis. This determines the measurement accuracies for each of the three metrics separately. Furthermore, it can be clearly demonstrated by the examination of the national network that in 90% of cases there is a series of geometrics that have a value that decreases compared to the previous half-year, while other geometrics value still is increasing.
Seismic hazard mapping using R-CRISIS
Authors: Cutia E , Țurcan V
Published: August 2021

This article presents methods and software used to develop a seismic hazard map. As an example, the territory of the Republic of Moldova is being studied, which is affected by subcrustal earthquakes of medium depth in the Vrancea seismic area. The elaboration of the map is based on the theoretical model of probabilistic seismic hazard assessment established and described in detail in the specialized literature. In order to facilitate and minimize errors, specialized software was used, one of this software is R-CRISIS, a software created and presented for premier in 1986 by Professor Mario Ordaz at the Institute of Engineering UNAM, Mexico and which is continuously being developed and improved. R-CRISIS allows the users to perform a big range of deterministic and probabilistic analyses through a user-friendly interface.
Remote optical measurements of cracks in concrete structures using computer image processing
Authors: Vashpanov Y , Heo G , Son J-Y , Podousova T
Published: August 2021

This report develops non-contact optical methods for measuring concrete cracks for remote diagnostics of hard-to-reach building surfaces using drones. The drone’s high-resolution digital camera captures remote close-up photography of the concrete surface under high light intensity levels. The digital image of the crack converted in a data matrix, each element of which contains information about the level of reflected light from the concrete surface and the crack. Using the formulas obtained by us earlier, with the help of computer processing of the image, the morphology of the crack in real geometrical dimensions can be calculated. Using special tools computer programs, the crack’s geometrical parameters can be measured maximal accurately as possible. The proposed remote optical method for non-contact detection of cracks in concrete when photographing with a drone from a close distance allows achieving an accuracy of measuring the length and width of a crack of 5%, and its depth of 10%.
Vibration analysis of the simply supported R/C beam
Authors: Stoynova I
Published: August 2021

A mechanical vibration can be of different origins-caused by machines, due to a shock impact, by motors, etc. In this paper the behaviour of a reinforced concrete beam with a static scheme of a simply supported beam under the action of vibrations has been studied. The paper presents differences between static and dynamic analysis of the simply supported reinforced concrete beam. Concrete and the reinforcement bars are modelled with their material characteristics by applying linear-elastic material models. The load area is in the middle of the beam. A numerical model by the Finite Element Method was developed. To perform the vibration analysis, a time-history analysis has been employed. Dynamic analysis of the numerical model was performed using a software product based on the Finite Element Method. The dynamic time-history analysis was adopted to determine the dynamic response of the simply supported R/C beam under the action of time variables.
Dynamic research of dome structures
Authors: Handruleva A
Published: August 2021

In this paper the dynamic responses of discrete single-layer domes are discussed. As objects of the study, computational models of domes have been analysed. These models differ in the type of their boundary conditions, the grid configuration, and in the height of the spheres. The analysis was conducted in two stages: a modal and a spectral analysis. In the modal analysis, a coefficient of the effective modal mass and the type of natural forms of vibration have been observed. Comparison has been made between CQC and SRSS being two different methods for combining modal contributions, as well as between two other methods of combining modal responses in the direction of seismic effects, namely: SRSS method and the “Rule of 30%”. The purpose of the study is to work out the dynamic response of the discrete single-layer spherical domes.
Numerical study of random material properties within a soil specimen
Authors: Amad M , Ray R P
Published: August 2021

Material properties derived from laboratory soil tests often assume that the property is uniform throughout the specimen. For some exceptional soils, this may hold true, but for many others it is obviously false. We have been performing cyclic and irregular torsional simple shear (TOSS) tests on hollow cylinder samples for decades and were intrigued by the idea of how to model inherently non-uniform specimens. As an added corollary, we wanted to understand the influence of imperfections (voids, inclusions) on the measured stress-strain behaviour in these tests. This paper examines two general classes of problems: (a) uniform specimens with inclusions of voids or imperfections, and (b) non-uniform specimens with random distributions of material properties within the specimen. Finite element modelling was performed on a TOSS specimen (ID = 4cm, OD = 6cm, L = 14cm) using a set of over 500 different elastoplastic material properties within the specimen. Various distributions (Normal, Log-normal, Bimodal) of stiffness and strength properties were examined. The results were examined as torque vs. twist curves since those values are typically measured in the TOSS laboratory test before being converted (with assumptions of uniformity) to shear stress-shear strain hysteresis. The Bimodal distributions were used to represent soils with distinct hard and soft zones. Additionally, distributions with some degree of spatial correlation were also examined.
Comparative analysis on laboratory bearing tests for beams made of OSB3 and of solid timber
Authors: Poenaru (Coflea) O A , Isopescu D N , Neculai O
Published: August 2021

Current times impose the usage of less raw building and more recycled materials. Wood is a material that can be recycled and processed in the factory in order to create new materials. Due to its mechanical characteristics, OSB3 has been chosen to create glued beams, which are hybrid elements with a configuration similar to GLULAM. This paper presents an analysis of the results obtained in four points bending tests on real scale beams made of solid wood and of glued OSB3 lamellae. The current research intends to compare solid wood beams with OSB3 glued beams, from failure load and elastic behaviour points of view.
A meshfree formulation for CFD and linear elasticity problems
Authors: Saucedo-Zendejo F R
Published: August 2021

This paper documents the development and application of a meshless procedure for computational fluid dynamics and linear elasticity problems. The meshfree nature of this method gives the advantage of dealing with highly distorted domains and even fragmentations without the need of using computationally expensive remeshing approaches and with a very simple implementation. A description of the implementation of this method and also the solutions of some benchmark problems will be presented in order to demonstrate the potential of this formulation for dealing with problems in these fields and to introduce promising future fields of application.
Design and wind simulation of steel structures in a parametric environment
Authors: Kis Á
Published: August 2021

Nowadays, parametric design and various simulation methods are gaining ground in almost every engineering and creative profession. The paper investigates the practical applicability of the combination of these methods, by analysing a specific freeform structure with Grasshopper 3D and OpenFOAM and pointing out the differences between the results of a CFD simulation and the recommended methods of the Eurocode. The case study highlights the new perspectives that are opening up in the field of structural design, especially in the examination of wind effects.
Numerical comparison between Hashin and Chang-Chang failure criteria in terms of inter-laminar damage behavior of laminated composite
Authors: Shao J R , Liu N , Zheng Z J
Published: August 2021

In this paper, a general three-dimensional finite element model composed of eight-node three-dimension cohesive elements and eight-node solid elements with reduced integration for low-velocity impact analysis of composite materials is established. Firstly, the continuum damage mechanics is applied to simulate the initiation and evolution of the intra-laminar damage. Based on cohesive zone model, the cohesive elements are inserted between layers to predict the inter-laminar damage. Three failure criteria, including 2D Hashin, 3D Hashin and Chang-Chang criteria, are coded in VUMAT and are implemented in ABAQUS/Explicit. The numerical results of energy time curves, force time curves, force displacement curves and damage distribution under three impact energies (7.35 J, 11.03 J and 14.7 J) are in good agreement with previously published data in literature, which indicates that the finite element model is suitable for studying the mechanical response and damage distribution of composites laminates subjected to low-velocity impact. Moreover, the influence of stacking sequence and friction coefficient on mechanical response and damage distribution is analyzed. It is concluded that the composite laminate with a stacking sequence of [45°/0°/−45°/90°]S can reduce the area of damage region compared to [0°/90°]2S because the ±45° layer can improve the shear resistance of composite laminate. Also, the computation accuracy will be the best when the friction coefficient is adopted between 0.5 and 0.7.
Alloying effect of Mg on microstructure and mechanical properties at 300 °C of Al–5Cu–1Mn–0.5Ni heat-resistant alloy
Authors: Chen Jinlong , Zhang Jianmei , Shen Honglei , Liao Hengcheng , Li Hualong
Published: August 2021

The effect of Mg alloying on microstructure and mechanical properties at 300 °C of Al–5Cu–1Mn–0.5Ni heat-resistant aluminum alloy was investigated by microstructure observation and tensile test. Alloying with 0.5 wt%Mg addition considerably increases the yield strength at 300 °C of samples at as-cast, as-solutionized and as-aged states. It also greatly enhances the strengthening effects from solution and ageing treatments, however, simultaneously, decreases the elongation greatly. During the solidification process of the alloy with Mg addition, a great amount of whisker-like Al–Cu–Mg compound phase is formed at the eutectic boundary zones in the form of ridge configuration, which is determined as AlCuMg intermetallic compound by TEM. During the solution treatment, this whisker-like AlCuMg phase is completely dissolved into Al matrix that leads to a remarkable rise in the increment of yield strength at 300 °C by solution strengthening. The alloying of Mg has a significant influence on the precipitation behavior during the ageing treatment, for examples, promoting the formation of finer θ′′ particles and a great number of Cu–Mg atomic clusters. During high temperature tensile test, theses clusters evolve into fine cube-like Al5Cu2Mg particles with orthorhombic structure. It is the significant microstructure evolution induced by alloying of Mg that leads to the great rise in yield strength at 300 °C. Addition of Mg in Al–Cu–Mn–Ni alloy dose not lead to the formation of meta-stable or stable S phase, but whisker-like AlCuMg and cube-like Al5Cu2Mg compounds are determined by TEM.
Structural, morphological and electrical properties of chitosan/methylcellulose blend polymer doped with different concentrations of NH4NO3
Authors: Abdulkareem Sarkew S
Published: August 2021

Polymer blend electrolytes based on chitosan: methylcellulose loaded with ammonium nitrate (NH4NO3) were fabricated by solution cast method and characterized by XRD, FTIR, EIS, FESEM, and TNM techniques. XRD is used to show the decrease of the crystalline structure. FTIR method is used to confirm the interaction between electrolyte elements. The maximum room temperature DC conductivity of 3.54 × 10−4 S cm−1 is provided by the highest conducting system using EIS data. The FESEM method showed that the morphology of the film has a uniform smooth surface at the highest salt concentration. This is in good agreement with the XRD, FTIR, and EIS results. The dielectric constant is high at the low frequency region due to electrode polarization. Transference number measurement (TNM) is used to show the dominant charge carriers. The values of the transference number of electron (telectron) and ion (tion) showed that the ions are dominant. The TNM measurement shows the compatibility of the system for electrochemical energy storage device application.
Spatial distribution characteristics of stomata at the areole level inMichelia cavalerieivar.platypetala(Magnoliaceae)
Authors: Shi Peijian , Jiao Yabing , Diggle Peter J , Turner Rolf , Wang Rong , Niinemets Ülo
Published: August 2021

Background and Aims

In hierarchically reticulate venation patterns, smaller orders of veins form areoles in which stomata are located. This study aimed to quantify the spatial relationship among stomata at the areole level.

Methods

For each of 12 leaves of M. cavaleriei var. platypetala, we assumed that stomatal characteristics were symmetrical on either side of the midrib, and divided the leaf surface on one side of the midrib into six layers equidistantly spaced along the apical–basal axis. We then further divided each layer into three positions equidistantly spaced from midrib to leaf margin, resulting in a total of 18 sampling locations. In addition, for 60 leaves, we sampled three positions from midrib to margin within only the widest layer of the leaf. Stomatal density and mean nearest neighbour distance (MNND) were calculated for each section. A replicated spatial point pattern approach quantified stomatal spatial relationships at different distances (0–300 μm).

Key Results

A tendency towards regular arrangement (inhibition as opposed to attraction or clustering) was observed between stomatal centres at distances <100 μm. Leaf layer (leaf length dimension) had no significant effect on local stomatal density, MNND or the spatial distribution characteristics of stomatal centres. In addition, we did not find greater inhibition at the centre of areoles, and in positions farther from the midrib.

Conclusions

Spatial inhibition might be caused by the one-cell-spacing rule, resulting in more regular arrangement of stomata, and it was found to exist at distances up to ~100 μm. This work implies that leaf hydraulic architecture, consisting of both vascular and mesophyll properties, is sufficient to prevent important spatial variability in water supply at the areole level.
XIV—Swimming Happily in Chinese Logic
Authors: Beaney Michael
Published: August 2021

Dipping in Chinese waters

pulled and pushed by Mo

we see how Zhuangzi caught us

like the happy fish we know

we follow their flow

words matching as they sort us
Use of Racial and Ethnic Categories in Medical Testing and Diagnosis: Primum Non Nocere
Authors: Kaufman Jay S , Merckx Joanna , Cooper Richard S
Published: August 2021

Background

Use of race and ethnicity is common in medical tests and procedures, even though these categories are defined by sociological, historical, and political processes, and vary considerably in their definitions over time and place. Because all societies organize themselves around these constructs in some way, they are undeniable facets of the human experience, with myriad health consequences. In the biomedical literature, they are also commonly interpreted as representing biological heterogeneity that is relevant for health and disease.

Content

We review the use of race and ethnicity in medical practice, especially in the USA, and provide 2 specific examples to represent a large number of similar instances. We then critique these uses along a number of different dimensions, including limitations in measurement, within- versus between-group variance, and implications for informativeness of risk markers for individuals, generalization from arbitrary or nonrepresentative samples, perpetuation of myths and stereotypes, instability in time and place, crowding out of more relevant risk markers, stigmatization, and the tainting of medicine with the history of oppression. We conclude with recommendations to improve practice that are technical, ethical, and pragmatic.

Medicine has evolved from a mystical healing art to a mature science of human health through a rigorous process of quantification, experimentation, and evaluation. Folkloric traditions, such as race- and ethnic-specific medicine will fade from use as we become increasingly critical of outdated and irrational clinical practices and replace these with personalized, evidenced-based tests, algorithms, and procedures that privilege patients’ individual humanity over obsolete and misleading labels.
Incidence, clinical relevance and therapeutic options for outflow graft stenosis in patients with left ventricular assist devices
Authors: Dimitrov Kamen , Kaider Alexandra , Angleitner Philipp , Schlöglhofer Thomas , Gross Christoph , Beitzke Dietrich , Granegger Marcus , Riebandt Julia , Wiedemann Dominik , Sandner Sigrid , Schaefer Anne-Kristin , Schima Heinrich , Laufer Günther , Zimpfer Daniel
Published: August 2021

OBJECTIVES

We reviewed our institutional experience with outflow graft stenosis (OGS) in 3 contemporary left ventricular assist devices (LVAD).

METHODS

Data from 347 consecutive adult recipients of LVAD [Medtronic HVAD (n = 184, 53.0%), Abbott HeartMate II (n = 62, 17.9%) and Abbott HeartMate 3 (n = 101, 29.1%)] implanted between March 2006 and October 2019 were analysed retrospectively. Primary study end points were the incidence of OGS necessitating treatment and survival on LVAD support.

RESULTS

During the study period, 17 patients (4.9%) developed OGS requiring treatment with a probability of 0.6% at 1 year, 1.9% at 2 years, 3.8% at 3 years, 4.7% at 4 years and 5.9% at 5 years of LVAD support. Notably, in 13.8% of patients, a compression-related narrowing of the outflow graft with a probability of 1.5% at 6 months, 1.8% 1 year, 6.0% at 2 years, 12.3% at 3 years, 15.4% at 4 years and 16.6% at 5 years of LVAD support with no difference between devices (P = 0.26) was observed. There was a trend towards increased risk of mortality with OGS (hazard ratio 2.21, 95% confidence interval 0.87–5.51; P = 0.09). OGS preferentially occurred in segments of the outflow graft covered by a protective coating.

CONCLUSIONS

OGS is a rare but potentially lethal complication during LVAD support. Modifications of pump design and implant techniques may be needed because OGS preferentially occurs within covered portions of the outflow graft. Systematic screening may be warranted.
Beyond Tehran and Nairobi: Can Attacks against Embassies Serve as a Basis for the Invocation of Self-defence?
Authors: Kajtár Gábor , Balázs Gergő Barna
Published: August 2021

Forty years have elapsed since the Iran hostage crisis, yet the question whether a state can lawfully resort to force in reaction to an attack against its diplomatic or consular mission remains unanswered. This issue is subject to contradictory scholarly interpretations, whereas self-defence as a justification regularly reappears in state practice. A recent example is provided by the US position regarding the killing of Qasem Soleimani in January 2020. This article revisits this controversial issue from an empirical perspective, focusing on extensive analysis of state practice based on 730 incidents. Both the empirical and the theoretical inquiry led the authors to call into question the possibility that states may lawfully rely on self-defence in such circumstances. Only one state has ever invoked self-defence regarding attacks against its embassies, and it only did so on five occasions, which were all contested by the international community. In all other 725 instances, the sending state and the international community reacted in ways other than the use of force. This research also analyses these various responses triggered by attacks against embassies. Moreover, it is virtually impossible to prove the fulfilment of the necessity and proportionality criteria of the action taken in self-defence in light of state practice over the last 70 years. Finally, this article also calls for a close re-reading of the Tehran Hostages judgment to challenge the judgment’s widely accepted interpretation as recognizing self-defence in such situations.