bluuebunny/crossref_metadata_2025 huggingface dataset:
Referentiality mechanisms in EU education policymaking: The case of the European Education Area
Authors: Kushnir Iryna
Published: January 2022

In 2017, the European Union (EU) initiated the development of the European Education Area (EEA). The referentiality approach frames an original and timely inquiry into how EU policymakers explain the reasons for the development of the EEA. This inquiry relies on thematic analysis of relevant key policy materials, produced by the European Commission and the Council of the EU. The findings highlight a range of internal and external referentiality mechanisms that EU policymakers use to justify the development of the EEA. Internal references are related mainly to education traditions in the EU as a strong foundation for the EEA and the source of its ideas; the beliefs that the EEA can help overcome the interlocking crises the EU has faced in its recent past in the area of education as well as more generally; as well as the organisation of the EEA as part of the functioning of the EU, with both mutually shaping each other. External references are used to build on this and boost the competitiveness of EU's education sector and the EU as a region in the world. These findings address important gaps in our knowledge about EU policymakers' reasons for the development of the EEA. They enrich the limited literature about the EEA, make a theoretical contribution by extending the application of the referentiality approach and call policy actors at all levels of the EEA to facilitate a shared understanding of the reasons for the development of the EEA to ensure that their work serves EEA's purpose.
Value cocreation in livestreaming and its effect on consumer‐simulated experience and continued use intention
Authors: Chou Cindy Yunhsin , Chen Ja‐Shen , Lin Shao‐Kai
Published: January 2022

Drawing on the literature related to value cocreation and narrative transportation, this study proposes a framework for examining the relationships among consumer and livestreamer value cocreation behaviors, consumers’ mentally simulated experiences, and their intention to continue using livestreaming services. Purposive and snowball sampling were used to recruit survey participants. A total of 463 individuals were enrolled to test the research model and its hypotheses. The value cocreation of consumers and livestreamers affects consumers’ mentally simulated experiences, which in turn affect their intention to continue using a livestreaming service. To verify this finding, a post hoc in‐depth interview was conducted with an e‐commerce manager with extensive experience in producing livestreaming programs. This study differs from previous works in this area in that it focuses on what drives consumers to use livestreaming services and examines the effects of value cocreation on consumers’ mentally simulated experiences, narrative transportation, and their intention to continue using livestreaming services.
Late gadolinium enhancement cardiac magnetic resonance imaging of ablation lesions after postinfarction ventricular tachycardia ablation: Implications for ventricular tachycardia recurrence
Authors: Ghannam Michael , Liang Jackson , Attili Anil , Cochet Hubert , Jais Pierre , Latchamsetty Rakesh , Jongnarangsin Krit , Morady Fred , Bogun Frank
Published: January 2022

Background

Late gadolinium enhancement cardiac magnetic resonance (LGE‐CMR) imaging distinguishes between intrinsic postinfarction scar and radiofrequency ablation lesion related scar (dark core lesions [DCLs]) in patients with prior ventricular tachycardia (VT) ablation procedures.

Objective

To combine LGE‐CMR and electroanatomic mapping data to describe the relationship between DCLs and recurrent VT among patients undergoing repeat ablations for postinfarction VT.

Methods

Consecutive patients with repeat ablation for postinfarct VT with LGE‐CMR before the repeat procedures were studied. Prior ablation procedures and implantable cardiac defibrillator electrograms were analyzed to determine new versus previously documented VT. DCLs were identified on preprocedure LGE‐CMR and registered to electroanatomic maps. A control group of patients undergoing repeat ablation procedures without imaging was included.

Results

Nineteen study patients and 14 control patients were followed for 2.6 (1.6–5.6) years (31 [94%] men, age 65.8 ± 8.4 years, ejection fraction 24.7 ± 10.3, p > 0.10 for all). DCLs corresponded to unexcitable tissue during repeat procedures (area 22.4 ± 15.1 vs. 22.9 ± 16.8 cm3, correlation coefficient = .93). Most VT target sites (39/50 [78%]) were in close proximity (<1 cm) to DCLs. Most DCL related VTs 32/39 (82%) were new VTs. Patients with LGE‐CMR imaging incorporated into their ablation procedures had improved 24‐month survival from VT (64% vs. 38%, log rank p < 0.02).

Conclusion

LGE‐MRI can identify prior ablation lesions corresponding to nonexcitable tissue during repeat ablation procedures for postinfarction VT. VT target sites are often located in close proximity to the DCL area that may function as a fixed border for reentry circuits. Registration of DCL from prior ablation may facilitate repeat ablation procedures.
Relationship between α‐genus human papillomavirus and non‐genital seborrheic keratosis: Report of new cases and updated review
Authors: Nellessen Tobias , Aoki Rui , Kammerbauer Claudia , Clanner‐Engelshofen Benjamin M. , French Lars E. , Reinholz Markus
Published: January 2022

Background

Seborrheic keratoses (SK) are the most common acquired benign tumor that affects middle‐aged or older adults with great cosmetic concern. Clinical and histopathological similarities of SK and common warts have been addressed by investigating the possible presence of human papillomavirus (HPV) DNA in SK. Previous studies suggested the association between α‐genus HPV and SK located on genital skin, whereas the causal relationship between α‐HPV and non‐genital SK remains controversial.

Aim

This study aimed to clarify the pathogenic involvement of α‐HPV in the development of non‐genital SK.

Methods

We analyzed α‐HPV DNA prevalence and HPV genotypes using a PCR‐based microarray on 51 skin samples presenting with histologically confirmed SK without any malignant changes. Correlation between the histological subtype of SK and their HPV DNA‐positive reactivity was also evaluated.

Results

Of 51 non‐genital SK, two (3.9%) skin samples were positive for α‐HPV DNA; high‐risk HPV 31 and low‐risk HPV 42 were found. Evaluation of HPV prevalence in different histological types of SK showed that both HPV‐positive cases were acanthotic type; 14.3% of acanthotic SK lesions were positive, while all of the other types were negative for α‐HPV.

Conclusions

This study demonstrates that α‐HPV positivity is very rare in common non‐genital SK. The rare α‐HPV‐positive SK lesions histologically belonged to the acanthotic type, implying a potential impact of HPV infection on epidermal hyperproliferation. Although a possible association cannot be excluded, our findings suggest that α‐HPV is not a major causative factor for non‐genital SK.
The rising interconnectedness of the insurance sector
Authors: Jourde Tristan
Published: January 2022

This paper examines the long‐term evolution of the linkages of the insurance sector with financial and nonfinancial companies. We develop a measure of connectedness using a multifactor model of weekly equity returns. The empirical analysis is conducted from 1973 to 2018, for 16 developed countries, at both the sectoral and institution levels. The results indicate that, unlike other sectors, the connectedness level of the insurance industry has strengthened over time. We also find that the linkages of the largest insurance companies with financial and nonfinancial firms are structurally different but as high as those of the largest banks.
Co-occurrence of genes encoding carbapenemase, ESBL, pAmpC and non-β-Lactam resistance among Klebsiella pneumonia and E. coli clinical isolates in Tunisia
Authors: Ben Sallem R. , Laribi B. , Arfaoui A. , Ben Khelifa Melki S. , Ouzari H. I. , Ben Slama K. , Naas T. , Klibi N.
Published: January 2022

This study aimed to investigate the molecular mechanisms of carbapenem and colistin resistance in K. pneumoniae and E. coli isolates obtained from hospitalized patients in Carthagene International Hospital of Tunis. A total of 25 K. pneumoniae and 2 E. coli clinical isolates with reduced susceptibility to carbapenems were recovered. Susceptibility testing and phenotypic screening tests were carried out. ESBL, AmpC, carbapenemase and other antibiotic resistance genes were sought by PCR-sequencing. The presence of plasmid-mediated colistin resistance genes (mcr-1-8) was examined by PCR and the nucleotide sequence of the mgrB gene was determined. The analysis of plasmid content was performed by PCR-Based Replicon Typing (PBRT). The clonality of isolates was assessed by PFGE and multilocus sequence typing (MLST). All of the isolates produced carbapenemase activity. They showed a great variation in the distribution of ESBL, AmpC, carbapenemase and other plasmid-mediated resistance determinants. K. pneumoniae isolates carried blaNDM-1 (n = 11), blaOXA-48 (n = 11), blaNDM-1 + blaOXA-48 (n = 1), blaNDM-1 + blaVIM-1 (n = 1), blaOXA-204 (n = 1), along with blaCTX-M, blaOXA, blaTEM, blaCMY, blaDHA and blaSHV genes variants on conjugative plasmid of IncL/M, IncR, IncFIIK, IncFIB, and IncHI1 types. Three sequence types ST101, ST307 and ST15 were identified. The mgrB alteration g109a (G37S) was detected in a single colistin-resistant, NDM-1 and OXA-48-coproducing K. pneumoniae isolate. The two E. coli isolates belonged to ST95, co-produced NDM-1 and CTX-M-15, and harboured plasmid of IncFII and IncFIB types. To our knowledge, this is the first report in Tunisia of NDM-1, OXA-48, and CTX-M-15 coexistence in colistin-resistant K. pneumoniae ST15.
The electron‐bifurcating FeFe‐hydrogenase Hnd is involved in ethanol metabolism in Desulfovibrio fructosovorans grown on pyruvate
Authors: Payne Natalie , Kpebe Arlette , Guendon Chloé , Baffert Carole , Ros Julien , Lebrun Régine , Denis Yann , Shintu Laetitia , Brugna Myriam
Published: January 2022

Desulfovibrio fructosovorans, a sulfate‐reducing bacterium, possesses six gene clusters encoding six hydrogenases catalyzing the reversible oxidation of H2 into protons and electrons. Among them, Hnd is an electron‐bifurcating hydrogenase, coupling the exergonic reduction of NAD+ to the endergonic reduction of a ferredoxin with electrons derived from H2. It was previously hypothesized that its biological function involves the production of NADPH necessary for biosynthetic purposes. However, it was subsequently demonstrated that Hnd is instead a NAD+‐reducing enzyme, thus its specific function has yet to be established. To understand the physiological role of Hnd in D. fructosovorans, we compared the hnd deletion mutant with the wild‐type strain grown on pyruvate. Growth, metabolite production and consumption, and gene expression were compared under three different growth conditions. Our results indicate that hnd is strongly regulated at the transcriptional level and that its deletion has a drastic effect on the expression of genes for two enzymes, an aldehyde ferredoxin oxidoreductase and an alcohol dehydrogenase. We demonstrated here that Hnd is involved in ethanol metabolism when bacteria grow fermentatively and proposed that Hnd might oxidize part of the H2 produced during fermentation generating both NADH and reduced ferredoxin for ethanol production via its electron bifurcation mechanism.
Mapping immature fruit colour‐related genes via bulked segregant analysis combined with whole‐genome re‐sequencing in pepper (Capsicum annuum)
Authors: Song Zhao , Zhong Jian , Dong Jichi , Hu Fang , Zhang Baige , Cheng Jiaowen , Hu Kailin
Published: January 2022

Fruit colour is one of the most intuitive economic traits attracting consumers' attention for horticultural crops. Many genes associated with mature fruit colour have been identified in pepper, but genes influencing immature fruit colour are mainly unknown. In the present study, pepper inbred lines with light‐yellow (CSJ009) and green (CSJ010) immature fruit colour were used as female and male parents, respectively, to generate an F2 segregation population. Genetic analysis indicated that the light‐yellow immature fruit colour in CSJ009 is controlled by a single recessive gene, tentatively named as ly. The single‐nucleotide polymorphism (SNP)‐index analysis and genetic linkage analysis delimited the ly locus into a 6.51 Mbp region on chromosome 9, and four candidate genes Capana09g000680, Capana09g000671, Capana09g000715 and Capana09g000692 were identified in the linkage region. Nonsense mutation of APRR2 may be responsible for the low carotenoid content in immature CSJ009 fruits. These results lay a foundation for future immature fruit colour improvement via molecular genetics approaches and further identification of new immature fruit colour‐related genes in pepper.
Equivalent Performance Parameters for Turboblowers and Compressors
Authors: Davis Hunt
Published: January 2022

The author defines the parameters of equivalent performance for turbocompressors and shows how they may be used for correlation of shop and field testing with design information. Three classifications of correlation are defined with different degrees of correlation accuracy. The first class includes cases where the correlation error is negligibly small, even when the test fluid is different from the design fluid. The second class includes cases where the correlation accuracy is reasonably good. The third class offers no satisfactory correlation conditions. It is proposed that similar concepts of correlation be recognized by and incorporated into the appropriate Power Test Code for turbocompressors.
On the Basic Mechanics of the Grinding Process
Authors: Backer W. R. , Merchant M. E.
Published: January 2022

New geometrical concepts of grinding are presented and combined with metal-cutting principles to predict grinding forces. Experimental evidence is used to show the dependence of grinding mechanics on three fundamental variables, the length and cross-sectional area of the undeformed chip, and the cutting speed. These same three variables are shown to have no effect on grinding ratio, the wheel wear varying only with the metal removed for the test conditions employed. Variations in grinding ratio from run to run are found to have a distribution in line with tool-life tests for other machining operations.
An Analog Study of a High-Speed Recording Servomechanism
Authors: Schwartzenberg J. W.
Published: January 2022

This paper presents an analysis of a high-speed recording servomechanism. Because of the nonlinearities present, the system is simulated on an analog computer. Minimum balancing times with a 100 per cent step-input signal are obtained for various combinations of system parameters. Several types of damping are considered, and the a-c carrier action of the amplifier is included in the simulation. The frequency response and following error of the system are also considered.
Experimental Measurement of Metal-Cutting Temperature Distributions
Authors: Reichenbach G. S.
Published: January 2022

Two new methods of measuring cutting temperatures have been evaluated. The first is a radiation technique using a lead-sulfide cell. The cell is arranged to sight through a small hole drilled in the work material sensing radiation from the shear plane and clearance face of the tool. Peak temperatures in these regions have been obtained but shear-plane temperature distributions could not be determined successfully. The second technique uses a 0.005-in. single wire imbedded in the side of a workpiece as a thermocouple. With orthogonal cutting the tool passed beneath the wire so that the wire passed up the tool face still imbedded in the chip. By this method it was possible to determine the temperature field throughout the chip and work. These temperature fields have been compared to theoretical predictions and show only fair agreement. The lack of agreement is due partially to the simplifying assumptions of orthogonal cutting and a true geometric shear plane necessary for theoretical solution. The necessity of locating the thermocouple junction on the side of the work introduced errors from side flow of the chip and certain other edge effects. The iteration procedure of Trigger and Chao has been extended to tools of any rake angle and simplified by use of a conducting-paper electrical analog.
Influence of Load and Thermal Distortion on the Design of Large Thrust Bearings
Authors: Baudry R. A. , Kuhn E. C. , Wise W. W.
Published: January 2022

High-capacity vertical waterwheel generators require large thrust bearings in which the load is carried on a thin hydrodynamic film of oil. Thermal and load distortion of the bearing parts have to be limited to a low value to permit the normal and complete formation of the oil film predicted by the hydrodynamic theory of lubrication. Excessive load and thermal distortion materially affect bearing performance and may result in bearing failure. This paper describes some design considerations given to vertical waterwheel-generator thrust bearings in order to avoid highly concentrated loading during the starting period, and to obtain minimum distortion of the pad during operation at normal speed and load.
Comparison of Semi-Empirical Solutions for Crack Propagation With Experiments
Authors: Frisch J.
Published: January 2022

The crack-propagation characteristics of two aluminum alloys and several steels have been investigated in sheet materials under uniaxial tension. Empirical formulas based on ultimate strength and initial crack length were found to be a sufficiently effective method for establishing the relative merit of a material in its resistance to crack propagation. Comparison of experimental data with criteria obtained from the energy-release rate or stress-concentration theory shows that neither method yields reliable material constants.
Formulations for the Thermodynamic Properties of Steam and Water
Authors: Schnackel H. C.
Published: January 2022

The thermodynamic properties of steam and water as presented in the well-known Keenan and Keyes’ Steam Tables are expressed as formulas and condensed tables. This is done to facilitate the calculation of steam and water properties on high speed digital computers. Methods of iteration and interpolation using these formulas and tables are discussed. Errors incurred in using the formulations as well as the ranges involved are also described.
Prediction of Flashing Water Flow Through Fine Annular Clearances
Authors: Agostinelli A. , Salemann V.
Published: January 2022

The flow of a flashing mixture of water and steam through smooth annuli of fine clearance has been investigated experimentally. Test data have been obtained with inlet conditions to 600 F and 3000 psi. Critical conditions have been observed experimentally up to these temperatures and pressures. With the assumption that the flashing mixture is homogeneous a method for the prediction of flow and two-phase pressure drop is presented and discussed.
Boiling Heat Transfer to Water Containing a Volatile Additive
Authors: Leppert G. , Costello C. P. , Hoglund B. M.
Published: January 2022

Aspects of local boiling in forced circulation when the boiling fluid contains small percentages of alcohol are discussed. Particular emphasis is placed on the improvement in smoothness of boiling and in the decrease of average bubble size when the additive is present, as contrasted with boiling distilled water. Experimental results, including photographs, are presented for surface boiling from the outside of a cylindrical stainless-steel tube placed normal to the flow. Data are also presented for the subcooled boiling of distilled water, and comparisons are made with correlations from the literature.
Static and Dynamic Characteristics of Compensated Gas Bearings
Authors: Richardson Herbert H.
Published: January 2022

A static and dynamic analysis of a general configuration of a compensated gas bearing is presented for the case in which the effects of shaft rotation on performance are negligible. The equations developed can be used quantitatively and are particularly useful in assessing the effects on static and dynamic performance of changes in design parameters such as fluid properties, compensation schemes, and geometry. To illustrate the use of the equations developed, a comparison is made between two common types of hydrostatic gas bearings—the pool bearing and the inherently compensated bearing—and a design example for a specific bearing requirement is worked.
The Effect of Wakes on the Transient Pressure and Velocity Distributions in Turbomachines
Authors: Meyer R. X.
Published: January 2022

In general, the blades of a multistage turbomachine move through a row of wakes shed from the blades of the preceding stage. This interaction between blade rows results in a transient fluctuation of the pressure distributions, which in turn can be expected to have an important effect on the drag, the maximum lift coefficient and, in the case of hydraulic machines, on the cavitation characteristics of the affected blades. In the paper, the time-dependent pressure gradient and the velocity are determined for the case of two-dimensional incompressible flow through lightly loaded cascades.
Optimization of Plate-Type Air Preheaters for Automotive Gas Turbines
Authors: Hryniszak W.
Published: January 2022

This paper deals with recuperative plate-type heat-exchanger elements for a composite air preheater for automotive gas turbines. The general requirements and optimization of the essential dimensions of such an element are discussed.

Such optimization leads to the smallest possible weight for a given temperature and pressure efficiency. As these two efficiencies affect the specific fuel consumption of the gas turbine, two further optimizations lead to: (a) The best pressure ratio of the turbomachines for given initial temperatures; and (b) the best temperature and pressure efficiency of the air preheater. The weight of this heat exchanger affects the performance of the vehicle propelled by the gas-turbine unit in different ways. Further optimization therefore leads to the best weight of the air preheater at a given average speed.

Cost considerations which affect the design of the element are influenced by the method of manufacture and the choice of materials as well as the method of maintaining clean channels in the heat-exchanger elements.
Optimal Synthesis of Linear Sampling Control Systems Using Generalized Performance Indexes
Authors: Kalman R. E. , Koepcke R. W.
Published: January 2022

This paper is concerned with the design of linear control systems so as to minimize some quadratic performance index. The method of design is applicable to both sampling and continuous control systems. Using the concepts of “state” and “transition matrix,” the design problem can be solved, via the technique of dynamic programming, by means of simple iterative computations. In this way, the classical Wiener method of design is extended in several different directions: (a) Using generalized performance indexes, (b) optimizing for classes of input signals rather than single inputs, (c) assuring stability of the optimally designed system.
Gyro-Integrating Mass Flowmeter
Authors: Akeley L. T. , Batchelder L. A. , Cleveland D. S.
Published: January 2022

This paper describes an integrating mass flowmeter designed for high-pressure natural-gas metering. The meter described provides direct reading of pounds of gas on a cyclometer register as well as electrical contacts for remote telemetering mass flow. No electronic elements are used in the design. A three-axis gyroscope is used for integrating. The meter is designed for 1 per cent integrating accuracy over 30 to 100 per cent of rated flow. It operates over a 20 to 1 flow range.
Optimization of Cathode Structure for Anode-Supported Planar Solid Oxide Fuel Cell
Authors: Fan Shengliang , Wang Guoli , Yang Lei , Liu Pengwei , Han Xu , Jin Zunlong
Published: January 2022

It is always an important research direction to improve the performance of solid oxide fuel cells (SOFCs) through structural optimization. For anode-supported SOFC, the thin cathode thickness results in an uneven distribution of oxygen concentration in the porous electrode, which limits the output performance. In this paper, a three-dimensional model of the anode-supported planar SOFC was established, and the thickness of the cathode diffusion layer in the area covered by the connector was increased to improve the uniformity of oxygen distribution in the cathode. The results show that increasing the thickness of the cathode diffusion layer under the connector can significantly improve the overall output performance of SOFC. The uniformity of oxygen concentration distribution in the cathode is improved, the local current density under the connector is increased, and the maximum output power density of the cell is increased by 29.14%. The results show that the output performance of the SOFC and the uniformity of gas distribution in the porous electrode can be improved by increasing the thickness of the cathode diffusion layer under the connector in the structure design and practical application of the SOFC. The research of this paper provides a reference for the optimization design of SOFC.
Large Eddy Simulation of the Layout Effects on Wind Farm Performance Coupling With Wind Turbine Control Strategies
Authors: Wu Chunlei , Wang Qiang , Yuan Renyu , Luo Kun , Fan Jianren
Published: January 2022

Large eddy simulation (LES) coupling with wind turbine control strategies is newly developed to quantitatively study the layout effects on wind farm performance. The turbine rotor is parameterized with an actuator line method (ALM), and the five-region generator-torque control and the proportional-integral (PI) pitch control are newly introduced to regulate the operation of the wind turbine. First, a dynamic inflow boundary condition is designed to validate the current simulation framework. The validation results show that the simulated power curve agrees well with the real power curve of the wind turbine, and the maximum power error of the simulation only accounts for 5% of the rated power. Then, to study the layout effects, four kinds of wind farm arrangements are designed by varying the alignment method and the turbine spacing. The results show that the staggered arrangement and increasing the stream-wise spacing are beneficial to reduce the velocity deficit. The power comparison results show that the staggered arrangement has obvious advantages among the four cases, and it increases the capacity factor (CF) by 25% and improves the wind farm efficiency by about 50% compared with the aligned arrangement. The present simulation framework can be used to optimize the turbine layout for the potential wind farms.
Influence of Cutting Conditions on Dimensional Integrity
Authors: Narayan Sumesh , Kumar Abhishek Kaushal , Ali Aruf , Mamun Kabir
Published: January 2022

This study investigates the effect of machining parameters correlating to the quality and precision of machined parts. The main focus is given to coordinate measuring machine (CMM) features, dimensional accuracy and surface roughness. Samples of three hardness materials were milled according to a standard design while varying machining parameters. The varied parameters were the type of milling machine used, feed rate and spindle speed. A CMM of 0.0001mm precision was used to measure the dimensions of the machined parts and analysis of variance (ANOVA) was used as the analysis to study the impact of each machining parameter on the quality and accuracy of the machined specimen. The study revealed that spindle speed of the milling machine, hardness of the material and the machine automation type is the factor that has a significant effect on the surface roughness of the machined features and hardness, spindle speed and a combination of hardness plus spindle speed had a significant effect on the dimensional accuracy of the machined features. The significant difference in data collection using the three CMM touch probes available was also studied, which revealed that the effect of changing probe diameter does not have any significant effect on a standard design feature when collecting data.
Application of Topology Optimization to Design a Structural Panel Subjected to Blast Loading
Authors: Schiffer Gillian , McMullen Kevin , Bruhl Jakob
Published: January 2022

The purpose of this study is to apply topology optimization to the design of a protective underbody panel for armored combat vehicles subjected to improvised explosive devices (IEDs). The increased use of IEDs by terrorist organizations over the last two decades has led to the death of thousands of soldiers and imposed critical damage to vehicles. There is interest in developing a protective panel that minimizes deflection and mass. The goal of this study is to design a lightweight, modular, and affordable panel, which provides increased protection to the vehicle occupants. Topology optimization may be used to create unique structures through a subtractive formulation. As additive manufacturing capabilities improve, topology optimization enables the design of efficient structures that are difficult to manufacture using traditional methods. Eight topology optimization studies were conducted and produced unique structural designs that were compared to established designs. The deflection, strain energy, and stress of optimized models from were compared to a hollow structural section (HSS) of equivalent mass and height. Results indicated the performance of optimized models were dependent on the topology optimization design goal. The methodology presented may be used in the future for projects which aim to minimize mass and maximize stiffness.
Fluid Flow in Between the Differentially Rotating Spherical Shells in the Presence of Toroidal Magnetic Field
Authors: Sharma Bharti , Srivastava Neetu
Published: January 2022

The behavior of fluid flow in differentially rotating shells with radii a and b where a < b, is discussed in the magnetic field’s presence. Out of the two significant elements of the magnetic field which are toroidal and poloidal, the toroidal magnetic field plays the dominant role for determining the behavior of fluid flow in the case of the rotating bodies. The solution for modelled equations is observed by perturbation method. Also the solution for flow quantities are observed by variable separable method for specific value of constant used in the abovementioned method.
Critical Shear Stress for Erosion Under Laminar Jet Flow
Authors: Pease Leonard F. , Bamberger Judith Ann , Minette Michael J.
Published: January 2022

Here we evaluate critical shear stresses for erosion under laminar jet flow. To date critical shear stresses for erosion, as embodied in Shields diagrams, have largely been developed for turbulent flow both experimentally and mathematically. However, curves on the Shields diagrams diverge among various models at lower particle Reynolds numbers. Indeed, how critical shear stresses for erosion develop under fully laminar jet flow conditions (not simply laminar boundary layers under turbulent flow) remains unclear. Here we address this gap, which is particularly important for mobilization of the smallest particles. We find the Shields parameter to be inversely proportional to the particle Reynolds numbers under laminar jet flow conditions similar to turbulent conditions.
Implementation of Reliability Design Theory on a Thin-Wall Vessel Structure
Authors: Le Xiaobin
Published: January 2022

A component will not reliable unless it is designed with the required reliability. Since the Advisory Group on Reliability of Electronic Equipment (AGREE) published the “Reliability of Military Electronic Equipment” in 1957, engineering reliability has gradually become an engineering branch to serve engineering design. But implementation process of reliability in mechanical components design is slow. There are maybe two main reasons: (1) There is a lack of statistical descriptions of material mechanical properties; and (2) There is a lack of appropriate reliability design approaches for mechanical component reliability design, especially for a fatigue design under cyclic loads. A thin-wall vessel is a typical mechanical component under combined stresses. It is extremely hard to establish the limit state function for a thin-wall vessel structure under cyclic loads by using the P-S-N curve approach. For the fatigue design issue, the author proposes to use the probabilistic component fatigue strength index and fatigue damage index model, which has been proposed by the author, for establishing the limit state function for the thin-wall vessel structure under cyclic loads, and then determining its reliability under cyclic loads. This paper presents and explains how to establish the limit state functions of a thin-wall vessel structure under different typical static loads and cyclic loads. Two case study examples are provided for implementing the proposed approaches to conduct the reliability calculation of a thin-wall vessel structure under static load and a cyclic load.
A Study on the Effects of Unmodelled Rotational Load Swing Dynamics on the Anti-Swing Control of an Overhead Crane
Authors: Lee Ho-Hoon
Published: January 2022

In this paper, the effects of the mass moment of inertia of the load on the anti-swing control of an overhead crane are studied with realistic computer simulations. First, the dynamic equations of motion are derived for a 2-dimensional overhead crane, based on Lagrange’s equations, in which the rotational load swing dynamics is included. Then, based on a coupled sliding surface [4], an anti-swing control scheme is designed without considering the rotational swing dynamics. In this case, the rotational load swing dynamics can be considered as unmodelled dynamics. The conventional anti-swing control scheme with an anti-swing trajectory generator will be simulated on the control of the overhead crane having the unmodelled dynamics. In this simulation, a delay of one-sampling period will be included in the feedback loop as in practical control applications in industry. For high simulation accuracy, the dynamic model of the crane including the rotational load swing dynamics will be solved by using the fourth-order Runge-Kutta formula with an adaptive step size.
Autonomously Controlled Robot With Trilateration-Based Localization for Optimized Excavation of Lunar Regolith
Authors: Smith Michael , Grabowsky David , Stanley Holden , Brake Jeremy , Browne Aidan
Published: January 2022

Extracting local resources from excavated lunar regolith will help support a sustainable presence on the Moon. For example, water ice beneath the lunar permanently shadowed region can be processed into liquid oxygen/hydrogen propellant. The availability of space acquired propellant could dramatically decrease the cost of Earth to space transportation. To address this need, this work proposes an autonomously controlled robot with trilateration-based localization for optimized excavation of lunar regolith. A proof-of-concept design for an autonomous lunar mining rover is presented. The autonomous rover is capable of traveling to known dig sites, excavating lunar regolith/water ice simulant, and transporting the lunar regolith/water ice simulant back to a collection sieve, without the need for user input. The work included phases for requirements and planning, conceptual design, detailed design, and testing for performance validation. Contributions of the proposed design include an autonomously controlled rover for excavation of lunar regolith, with design optimization to maximize the amount of successfully deposited material. The proposed design offers an optimal balance between opposing cost functions and design constraints for reducing the size and weight of the rover, while maximizing the operational performance of the rover for mining, transit, and depositing.
Comparison of Finite Element Modeling With Measured Deflection of Spiral Flat Oval Duct
Authors: Paruchuri Avinash , Liu Jane , Idem Stephen
Published: January 2022

Deformation was measured as a function of internal static gauge pressure for galvanized steel spiral 12 in. × 43 in. (305 mm × 1092 mm) flat oval ducts. Both unreinforced and externally reinforced ducts were considered. Dial deflection gauges were used to measure the duct deformation at prescribed locations on the top and bottom surface of the test duct and compared to corresponding predictions generated using a nonlinear finite element model that accounted for the self-weight of the duct walls. The Average Wall Thickness (AWT) method was utilized to account for the presence of a continuous spiral seam. Shell elements were employed to represent the thin-walled structure of the ducts. External trapeze reinforcements spaced 3 ft (0.91 m), 6 ft (1.83 m), and 12 ft (3.66 m) apart were modeled using beam elements. The non-linear finite element model of the duct system was found to yield realistic deformation predictions. It was concluded that finite element modeling can be used to guide decisions regarding the selection of a thicker duct wall, or inclusion of either internal or external reinforcement, if concerns exist about excessive duct or reinforcement deformation caused by high internal gauge pressures.
Intelligent Process Control Following Industry 4.0 Trends
Authors: Guerra-Zubiaga David , McMichael Grayson , Segura-Velandia Diana , Aslam Maria , Yim Seung-Woo , Anderson Zack , Goh Yee Mey
Published: January 2022

Industry 4.0 is the next phase in the industrial revolution, and it is considered a key factor for advanced process control. This paper is focused on Industry 4.0 aspects to support better process control through a Manufacturing Execution System (MES). Some intelligent manufacturing decision systems require complex infrastructures that make advanced feedback control possible. The motivation of this paper is exploring the paradigms such as Industrial Internet of Things (IIoT), Big Data collection, Cloud Manufacturing (CM), and Machine Learning (ML) to provide better manufacturing support decisions in process control. This paper proposes a new approach at MES providing more intelligent process control through the integration of IIoT, CM, and ML. This research effort created a Process Control Training Bench (PCTB) as experimental infrastructure to implement a process control system incorporating Industry 4.0 trends and applying ML to analyze and predict anomalies.
Optimization of CNC Milling of General-Purpose Poly (Methyl Methacrylate)
Authors: Wambua J. M. , Mwema F. M. , Akinlabi E. T. , Tanya Buddi
Published: January 2022

The purpose of this study was to investigate the impact of CNC milling parameters on the material removal rate (MRR) and surface roughness (Ra) of the general-purpose PMMA. The milling parameters considered were cutting speed, axial depth of cut and feed rate, each having four levels obtained through experimental trial and error. The levels were 300 rpm, 700 rpm, 1300 rpm, and 2000 rpm for the cutting speed; 0.3 mm, 0.8 mm, 1.5 mm, and 2 mm for the axial depth of cut; and 50 mm/min, 100 mm/min, 200 mm/min, and 350 mm/min for the feed rate. The Taguchi technique was used to design the experiments and carry out the analysis and optimization with an L16 orthogonal array. From the analysis, the optimal milling parameters for the maximum MRR were a cutting speed of 300 rpm, an axial depth of cut of 2 mm, and a 350 mm/min feed rate. The optimal CNC milling parameters for the least Ra were obtained at a cutting speed of 2000 rpm, an axial depth of cut of 0.3 mm, and a 50 mm/min feed rate. An ANOVA conducted depicted that all three factors were significant towards the MRR with the feed rate having the highest percentage contribution (48.8%), followed by the depth of cut (38.3%), and lastly, the cutting speed (9.8%). An ANOVA for Ra depicted that cutting speed and feed rate were the most significant factors. The axial depth of cut was insignificant towards the mean surface roughness. In terms of percentage contributions to the mean surface roughness, the cutting speed had the highest contribution (59.9%), followed by the feed rate (19.4%), and lastly, the axial depth of cut (13.9%).
Research on the Application of Electric Heating Floor in Railway Vehicles
Authors: Zhang Haifeng , Jia Na , Liang Jingwen , Cao Yanhua , Liu Xianfeng
Published: January 2022

With the rapid development of rail transit vehicle technology in recent years, railway vehicles are constantly developing in novel directions of lightweight, integration, intelligence, as well as environmental protection and energy saving. The application of electric heating floors in railway vehicles is one of the innovative attempts. This paper first illustrates the working principle, applicable standards, typical structure, mechanical performance, and technical parameters of the electric heating floor. Subsequently, simulation analysis on the heating floor samples is conducted, and the simulation data of compressive strength is obtained for this heating floor. The result of the analysis illustrates that the mechanical performance of the heating floor is not distinct from the normal floor, which meets the requirements of railway vehicle utilization. Then, simulation and comparison between the railway vehicle heating system using traditional heaters and electric heating floors are performed, to evaluate the heating effects in different ambient temperatures. Finally, this paper explores the technical difficulties and application prospects of the heating floor in railway vehicles.
Modeling and Station-Keeping Control of an Underwater Vehicle Manipulator System Through Reactions Wheels
Authors: de Oliveira Éverton L. , Donha Decio C. , Cardoso Reginaldo
Published: January 2022

An Underwater Vehicle-Manipulator System (UVMS) is a complex and highly non-linear multibody dynamic system used in Inspection, Maintenance and Repair (IMR) operations. Beyond the disturbances caused by the hydrodynamic forces, the UVMS is also subjected to the dynamic coupling between the Underwater Unmanned Vehicle (UUV) and the manipulator. This coupling affects the attitude and position of the UUV, which should remain stationary while the manipulator moves. The correct compensation of such coupling could be achieved through precise model-based control or, e.g., with signals produced by a force/torque sensor mounted between the UUV and the manipulator. However, the former approach is almost impossible to achieve, and the latter is very difficult to implement. Given these problems, this paper proposes a station-keeping control scheme based on Reactions Wheels (RWs) as inertial actuators for the attitude stabilization of a UUV under the action of the disturbances induced by the manipulator. The effectiveness of the proposed control scheme is validated here through numerical simulation, taking as a case study a planar UVMS consisting of a UUV and a two-link serial manipulator. The proposed control system provides better performance on the station-keeping when compared with a model-based decoupling controller. Moreover, it leads to lower energy consumption, which can increase the autonomous capabilities of the UVMS.
Effect of Glycol Aqueous Solution Properties on Battery Cooling Performance Based on Cold Plate
Authors: Zhang Hongya , Li Chengshuai , Xie Yangsu , Radwan Ali , Fang Haisheng
Published: January 2022

A three-dimensional analysis of an 8s1p (8 series and 1 parallexl batteries in a stage) lithium-ion battery module consisting of 8 prismatic batteries is performed using a multi-domain modeling framework. The well-known Newman, Tiedemann, Gu, and Kim (NTGK) model is used for modelling. A thermal management system based on liquid cooling via cold plates utilizing glycol aqueous solution (GAS) is proposed. Cooling simulations of the battery module are carried out at different GAS volume concentrations and flow velocities. The temperature evolutions at different volume concentrations and inlet flow velocities are determined, and the results are found to be in good agreement with the experiments. Strategies for modifying the properties of GAS to release the heat generated by the battery module are proposed. It is found that, the cell temperature and temperature gradients were maintained at a tolerable level at a suitable inlet flow velocity and volume concentration of GAS, even at a 5C discharge rate. The simulation and experimental results demonstrate that the temperature difference between the 8 battery cells reaches the minimum when the volume concentration of GAS is 70%, which means that the optimum cooling uniformity of the battery module can be reached at this volume concentration.
An Overview of the Research Landscape in the Field of Safe Machine Learning
Authors: Siedel Georg , Voß Stefan , Vock Silvia
Published: January 2022

The applicability of ML components in safety-critical systems will significantly depend on whether it will be possible to provide a comprehensive proof of their safety. Three research questions (RQ) are answered in order to provide a starting point for future activities towards the risk assessment of safety-critical systems containing ML components. First, special emphasis was placed on the design of a literature search strategy in order to enable quantitative insights into a representative set of publications (RQ1). Taxonomy analysis, bibliographic data visualization and compiled findings of reviews were therefore combined. A categorization of identified methods towards improving, ensuring and assessing safe machine learning was developed (RQ2). Then, a comparison was made with those methods for safety-critical software that are recommended by the functional safety standard IEC 61508 (RQ3). The comparison and quantification of research activity revealed imbalances within separate research areas. The conclusion is drawn that for the safety assessment of ML systems a comprehensive toolbox of combined methods needs to be converged from procedures within existing safety standards and the broad spectrum of methods proposed by current scientific publications.
Interaction of T-Stiffener on A0 Lamb Mode Propagation Behavior in Thin Plate
Authors: Sun Jiaying , Yu Zexing , Xu Chao
Published: January 2022

Integrally T-stiffened plates are widely used in aerospace, marine and other engineering structures. When elastic guided wave method is used to detect the damage of such structures, it is necessary to well understand the wave propagation behavior in these structures to further mature the guided wave SHM method. In this paper, the interaction between the fundamental anti-symmetric guided Lamb mode (A0) and T-stiffener in an integrally stiffened thin plate is studied by finite element numerical simulation. The propagation behavior of A0 mode in stiffened plate is actuated using a piezoelectric wafer active sensor. The characteristics of wave propagation caused by the presence of stiffener are analyzed in time domain using response signals and displacement snapshots. The results show that the existence of stiffeners causes obvious mode conversion. With the change of excitation frequency, the reflection and transmission behaviors of guided waves in A0 and S0 modes change obviously.