bluuebunny/crossref_metadata_2025_split huggingface dataset:
Research on current control strategy of overvoltage flexible suppression device based on cascaded linear-nonlinear active disturbance rejection controller
Authors: Niu Haichun , Liu Xiaoling , Liu Yu , Qin Fuzhen , Huang Gaiyun 
Published: May 2024

In order to improve the immunity and speed tracking performance of active inverters in resonant overvoltage flexible suppression under load variation, parameter perturbation, and other uncertainties, a current control strategy of a resonant overvoltage flexible grounding device based on a cascading linear-nonlinear active disturbance rejection controller is proposed in this paper. First, the mathematical model of the flexible device considering load disturbance and parameter mismatch is established. Second, a cascade of linear and nonlinear extended state observers is designed to estimate and compensate the uncertain disturbance of the system in real time. The former linear extended state observer ensures the stability of the system under large disturbance, and the latter nonlinear extended state observer further improves the estimation accuracy of the disturbance by using the nonlinear mechanism. Finally, the flexible grounding system based on PI control and cascaded linear-nonlinear active disturbance rejection control (CL-NLADRC) is simulated and compared. Compared with PI control, NLADRC, and CLADRC, the current drop of the proposed CL-NLADRC during loading is 0.03 kA, which is 81.1%, 85.7%, and 73% of the three, respectively, and the regulation time is 13 ms, which is 82%, 75%, and 18.7% shorter than the three, respectively. The speed increase during load shedding is 93.5%, 80.5%, and 74.3% of the three, and the adjustment time is shortened by 80%, 73%, and 28%, respectively. The superiority of the proposed method is verified.
Infrared spectroscopy of the syn-methyl-substituted Criegee intermediate: A combined experimental and theoretical study
Authors: Zou Meijun , Hassan Yarra , Roy Tarun Kumar , McCoy Anne B. , Lester Marsha I. 
Published: May 2024

An IR–vacuum ultraviolet (VUV) ion-dip spectroscopy method is utilized to examine the IR spectrum of acetaldehyde oxide (CH3CHOO) in the overtone CH stretch (2νCH) spectral region. IR activation creates a depletion of the ground state population that reduces the VUV photoionization signal on the parent mass channel. IR activation of the more stable and populated syn-CH3CHOO conformer results in rapid unimolecular decay to OH + vinoxy products and makes the most significant contribution to the observed spectrum. The resultant IR–VUV ion-dip spectrum of CH3CHOO is similar to that obtained previously for syn-CH3CHOO using IR action spectroscopy with UV laser-induced fluorescence detection of OH products. The prominent IR features at 5984 and 6081 cm−1 are also observed using UV + VUV photoionization of OH products. Complementary theoretical calculations utilizing a general implementation of second-order vibrational perturbation theory provide new insights on the vibrational transitions that give rise to the experimental spectrum in the overtone CH stretch region. The introduction of physically motivated small shifts of the harmonic frequencies yields remarkably improved agreement between experiment and theory in the overtone CH stretch region. The prominent features are assigned as highly mixed states with contributions from two quanta of CH stretch and/or a combination of CH stretch with an overtone in mode 4. The generality of this approach is demonstrated by applying it to three different levels of electronic structure theory/basis sets, all of which provide spectra that are virtually indistinguishable despite showing large deviations prior to introducing the shifts to the harmonic frequencies.
Human electrical circuits: interactive learning with plasma ball
Authors: Thakur Abhay Singh , Dubey Shivam , Vaish Rahul 
Published: May 2024

Abstract
Plasma ball is widely used for home decoration. This can also be used to demonstrate various scientific phenomena. Here, do-it-yourself activity was performed to demonstrate concepts of electrical resistance, their combinations, importance of voltage and electrical current etc. Students were acted here as resistance elements and human circuits were formed to teach electrical circuits.
Flavor mixing and solution structures in Dyson–Schwinger equations for a two-flavor system
Authors: Chao Xue-ao , Liu Yu-xin 
Published: May 2024

Abstract
We solved the Dyson–Schwinger (DS) equations for a two-flavor system with symmetry to study its flavor mixing effects. Initially, we employed the point interaction model and bare vertex approximation to reveal the structure of the solutions. Using the point interaction model, the DS equations can be solved analytically, and we found that these solutions can be classified into three groups, each forming an ellipse. These solutions exhibit SO(2) symmetry, while the original SU(2) symmetry at the Lagrangian level is dynamically broken to SO(2), corresponding to the emergence of flavor mixing effects. However, this flavor mixing effect does not manifest in the final physical state. By utilizing the system’s SO(2) symmetry, we can diagonalize the propagators of the DS equations, eliminating the flavor mixing effect but causing the originally degenerate masses at the Lagrangian level to split. These mass eigenstates have identical quantum numbers but different masses. If we can correspond these to quark particles of different generations, we can explain why the three generations of quarks have different masses and obtain the corresponding quark mass spectrum. Finally, we provide the corresponding numerical results using a more realistic interaction model.
Optimization design for moderator, reflector, and shielding of Deuterium-Deuterium neutron source
Authors: Ma Baolong , Yan Mingfei , Li Xiaobo , Jiang QuanXu , Wang Sheng , Liu Zhihua 
Published: May 2024

Abstract
Deuterium-Deuterium (D-D) neutron source, which could be
used in both laboratory and outdoors due to its light weight, small
volume and low cost, has been widely applied in thermal neutron
imaging (TNI) and prompt gamma-ray neutron activation analysis
(PGNAA). And the its optimization design is to obtain highly intense
thermal neutrons and low dose rate around the facility with light
weight and compact volume. In this paper, the genetic algorithm (GA)
combined with MCNP6 was applied to globally optimize moderator,
reflector, and shielding structures. As a result, the optimized
thermal neutron intensity increased by 1.68 times, while the dose
rate, weight and volume respectively decreased by 37%, 52%, and
27%, compared with the data based on the current design. This
method could be an effective tool for the compact neutron source
design.
Assessing climate resilience in rice production: measuring the impact of the Millennium Challenge Corporation’s IWRM scheme in the Senegal River Valley using remote sensing and machine learning
Authors: Fionnagáin D Ó , Geever M , O’Farrell J , Codyre P , Trearty R , Tessema Y M , Reymondin L , Loboguerrero A M , Spillane C , Golden A 
Published: May 2024

Abstract
Satellite remote sensing (RS) and machine learning can be combined to develop methods for measuring the impacts of climate change on biomass and agricultural systems. From 2015 to 2023, we applied this approach in a critical earth observation-based evaluation of the Irrigation and Water Resources Management component of the Millennium Challenge Corporation’s Senegal Compact. This project, funded by the United States Agency for International Development (USAID), was implemented in the Senegal River Valley from 2010 to 2015. Utilising these techniques, we successfully mapped rice cultivation areas, deciphered cropping practices, and analysed irrigation systems responses to different climatic conditions. A marked increase in cultivated rice area was found particularly in regions targeted by the project intervention. This is despite prolonged drought conditions which underscores a significant climate adaptation benefit from these irrigation works. We observed a notable dip in rice cultivation area in 2020, possibly due to the COVID-19 pandemic, followed by a recovery to pre-pandemic levels in 2023, likely aided by previously funded USAID’s socio-economic resilience programmes in the region. Economic analysis of increased rice yields in the region translates to approximately US$ 61.2 million in market value since 2015, highlighting the economic returns from the project investment. Both the RS data and ground audits identify issues regarding post-project deterioration of irrigation infrastructure, emphasising the need for long-term maintenance of irrigation infrastructure to support climate adaptation benefits arising from irrigation. With a focus on crop irrigation, our findings stress the critical role of climate adaptation interventions for maintaining agricultural productivity in the face of adverse climate shocks. It further highlights the necessity of continuous investment and maintenance for ensuring climate resilient agrifood systems.
Stabilization of approximate GHZ state with quasi-local couplings
Authors: Martin Vincent , Sarlette Alain 
Published: May 2024

Abstract
We propose a reservoir design, composed of fixed dissipation operators acting each on few local subsystems, to stabilize an approximate GHZ state on n qubits. The main idea is to work out how a previously proposed sequence of two stabilization steps can be applied instead in appropriate (probabilistic) superposition. We examine various alternatives to synchronize the superposition using local couplings only, thanks to a chain of ‘clock’ ancillas or to additional levels on the data subsystems. The practical value of these alternatives depends on experimental constraints. They all feature a design tradeoff between approximate stabilization fidelity and protection against perturbations. These proposals illustrate how simple autonomous automata can be implemented in quantum reservoir engineering to replace sequential state preparation procedures. Encoding automaton actions via additional data levels only, appears particularly efficient in this context. Our analysis method, reducing the Lindblad master equation to a Markov chain on virtual output signals, may be of independent interest.
Investigation of the influence of cobalt content and grain size of WC-Co cemented carbides on wear when shear cutting electric sheet metal
Authors: Schrepfer Agnes , Steinlehner Florian , Volk Wolfram 
Published: May 2024

Abstract
In the production of electrical machines, shear cutting of electrical steel laminations before further processing into rotors and stators represents an essential manufacturing process. Investigations have shown that using abrasively worn active elements while shear cutting increases the hysteresis losses in the electrical steel sheet due to introduced deformations and resulting residual stresses. Therefore, knowledge of suitable tool materials is of great importance for producing high-quality electric motors. Due to its high silicon content, electrical steel has a strong abrasive effect on the tools, which is why Tungsten carbide cobalt (WC-Co) cemented carbides are commonly used. In this work, continuous stroke tests are carried out on an electric sheet with punches made of different WC-Co cemented carbides, differing in cobalt content and grain size. The punches are examined with increasing wear regarding cutting-edge geometry, surface condition and microstructure. The resulting cutting parts are inspected for cutting surface characteristics. In addition, the influence of geometry and tribology of the punches regarding residual stresses in the material is investigated by FEM-Simulation. The investigations will provide information on the wear development and causes when shear cutting electrical sheets and the effects on electric losses.
Investigation of Temperature Impact on Friction Conditions in Running Production of Automotive Body Components
Authors: Barlo A , Sigvant M , Pilthammar J 
Published: May 2024

Abstract
During the running production of automotive body components drifts in the process window is seen causing problems with non-conforming parts. Up until now, these drifts have been counter-acted based on the knowledge and experience of the press line operators. This experience-based process control will however become more troublesome in the future as recycled material grades will undoubtedly present larger in-coil variations in material parameters and effect also the friction conditions from component to component.
The following study will present two cases from production of the Volvo XC60. For the two cases, the initial simulations made for the components showed a safe part, but during running production failure occurred suspected to be due to temperature effects in the tribology system. The study will furthermore present updated simulations considering developing thermal effects to replicate the failures, as well as present both standard and thermal simulations of the adjustments made in production.
Characterization of microstructural evolution pattern toward nano-scale in commercial-purity titanium by incremental sheet forming
Authors: Li W Q , Chang Z D , Chen J 
Published: May 2024

Abstract
In the present investigation, a commercial-purity titanium sheet was formed by a flexible sheet metal forming method, incremental sheet forming (ISF), to investigate its microstructure evolution. The deformation microstructures across the wall of formed parts were systematically examined by optical microscopy (OM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and high resolution TEM (HRTEM). Microstructural evolution from millimeter- to nano-scale was explored, with special attention paid to the refinement below 100 nm. A general pattern of structural evolution begins with the formation of uni- and multi-directional twins, which is accompanied by the initiation and development of ultrafine lamellar structure and final evolution of nano-lamellar structure and nano-equiaxed structure. A twinning-dominated process that was supplemented with dislocation slip-dominated one governed the microstructural evolution toward nano-regime. The strain-induced evolution of nano-lamellar and nano-equiaxed structures were discussed, of which the underlying refinement mechanism was analyzed. This technique was promising to offer an optional route for realizing the strengthening of metal parts via synthesizing nanostructures, showing potential scientific and technological importance in fabricating the high-strength metal formed productions for further meeting industrial applications.
Superplastic deformation behavior of low Al–added medium Mn steels with and without Ti and Mo elements
Authors: Yuan Pufan , Zhang Hongtao , Chao Qi , Sun Chenyu , Jia Bowen , Tang Shuai , Yan Haile , Hodgson Peter , Cai Minghui 
Published: May 2024

Abstract
Fe-Mn-Al-C medium Mn steels were found to reveal extraordinary superplasticity and have significant potential for forming the complex structural parts due to high strength, excellent ductility and material cost. In present study, the effect of tensile deformation temperature on the superplastic deformation behavior of a cold-rolled low Al-added medium Mn steel was studied. A maximum tensile elongation of approximately 1170% was obtained at 745 °C and 10−2 s−1, which is to our best knowledge the highest low-temperature-high-strain-rate superplasticity in medium Mn steels. Also, the role mechanism of microalloying elements such as Ti and Mo was revealed to further enhance the strength level of superplastic medium Mn steels. In view of the representative microstructural features, such as equiaxed grains, random texture, and sluggish grain growth, grain boundary sliding is thought to be the dominative mechanism during the high-strain-rate superplastic deformation.
High speed impact cutting (HSIC) of advanced high strength steel 42SiCr under exploitation of adiabatic shear bands
Authors: Birnbaum P. , Kunke A. , Kräusel V. 
Published: May 2024

Abstract
Shear Cutting of Advanced High-Strength Steels poses technological challenges due to the substantial mechanical loads imposed on cutting tools, leading to elevated wear rates. A strategy for cutting high-strength materials involves the utilization of high-speed impact cutting (HSIC), wherein component separation occurs along a locally adiabatically heated shear band, resulting in reduced cutting forces. The steel alloy 42SiCr undergoes heat treatments involving Quenching+Tempering (Q+T) as well as Quenching+Partitioning (Q+P) for two sheet thicknesses. This results in the formation of martensitic microstructures with varying retained austenite content, as determined through X-ray Diffraction (XRD). Subsequently, the heat-treated steel samples are subjected to tensile testing for mechanical property evaluation, revealing ultimate tensile strengths exceeding 1500 MPa and fracture elongations ranging from 2 % to 12 %. Following this, the material is subjected to HSIC using the AdiaPress Adia 7 machine, employing predefined cutting energies. It is observed that both Q+T and Q+P-treated materials can be successfully cut using HSIC, although distinct cutting edge morphologies are evident. Optical examinations of the cut edges, conducted through top-view and cross-sectional analysis using Scanning Electron Microscopy and 3D laser scanning microscopy, confirm the presence of adiabatic shear bands and discrete zones.
Biaxial Tensile Testing of Cruciform Samples to Determine the Impact of Pre-Strain on the Forming Limit Diagram of Aluminum Alloy 5052 through Finite Element Simulation
Authors: Pawar Shrutee Pradeep , Kumar Pavan , Narasimhan K. 
Published: May 2024

Abstract
The present work focuses on the effect of pre-strain on the forming limit curves (FLCs) of aluminium alloy 5052 sheet of 2.5 mm thickness using cruciform samples. To identify the effect of pre-strain on the FLC, the finite element simulations are performed on cruciform samples. The cruciform samples are deformed to a small level of pre-strain in different strain paths. Thereafter, the further deformation under the various strain paths to measure the effect of pre-strain on the forming limits are carried out. Pre-strain in uniaxial, plane strain and biaxial loading conditions are considered in this work. For each case, i.e., uniaxial, plane strain and biaxial conditions two pre-strain conditions are considered. The cruciform samples are carefully thinned in the central region to promote development of large plastic strains there and eventually to neck and fail. The output obtained through simulations are presented in terms of forming limit curves for various strain paths.
Applicability of the formability evaluation method for advanced high strength steels
Authors: Lian Changwei , Niu Chao , Han Fei 
Published: May 2024

Abstract
The use of high strength and ultra-high strength steels has become the main technical solution for reducing vehicle weight and improving safety. It is more complicated to evaluate the formability of advanced high strength steels with different microstructure and deformation characteristics. In this paper, the applicability of existing formability evaluation methods for advanced high strength steels has been verified by experiment and theoretical analysis. The experiment and data analysis of conventional formability evaluation methods, such as strain hardening index, forming limit curve and hole expansion ratio, were carried out on advanced high strength steels, such as dual-phase steel, complex-phase steel, quenched and tempered steel and dual-phase steel with high formability, which are widely used in automotive industry. It is found that due to the complex work hardening characteristics of advanced high strength steels, the work hardening homogenization and forming limit cannot be characterized by a single work hardening index or forming limit diagram, and the standard hole expansion method cannot reflect the quality sensitivity of the formed edge. A new formability evaluation index is proposed and discussed, which can be used to more accurately compare the formability of advanced high strength steels and provide a reference for material evaluation and part selection.
Cryogenic Deep Drawing Tool Design for Reduced Heat Transfer
Authors: Tulke M , Brosius A 
Published: May 2024

Abstract
Subject of this study is the usage of macro-structured tools for deep drawing of aluminum alloys at cryogenic temperatures in order to increase the drawing depth. The advantage of the macro-structure is the reduced contact area, which primarily leads to a reduction in frictional forces in the flange area and also minimizes the heat transfer from the tool to the cooled sheet metal. In addition to the geometry of the tools, the heat transfer is also influenced by the thermal properties of the tool materials. Therefore, the tool must be designed to reduce heat flux and thermal diffusivity. In this regard, substitute materials for the tools, specifically polymer, and steel-shielded polymer, were investigated. In this context, the heat transfer coefficients between the tool material and the aluminum blank are determined experimentally. The influence of thermal conditions on the cryogenic deep drawing process are investigated numerically and experimentally. The result of the study is an improved process understanding to ensure the blank temperature in a cryogenic range and increase the resistance against bottom cracks.
Development of a novel forming tool for the production of high-strength aluminum components with tailored properties
Authors: Rigas N , Merklein M 
Published: May 2024

Abstract
Because of growing environmental and technical requirements, the efficient manufacturing of components with tailored properties using recyclable materials is mandatory. The combination of high-strength aluminum alloys and thermal-assisted forming operations is an innovative method for the production of components with varying mechanical properties. By locally adjusting the cooling rates during a thermo-mechanical forming operation, it is possible to modify the microstructure and precipitation conditions. A subsequent aging operation causes different microstructural and mechanical characteristics. This allows both deep-drawing and adjustment of the component properties in one single step. For this reason, this contribution focuses on the production of components with tailored properties. With the aid of a non-contact measuring system, previous investigations have proved that mechanical material properties can be adapted during a forming process by adjusting the cooling rates. In this contribution, this knowledge is transferred to a novel temperature-controlled rectangular cup tool. A variation of the local tool temperature and holding duration in the tool will be carried out. Then, the mechanical and microstructural properties of the manufactured components will be characterized through hardness and DSC investigations. In addition, the influence of different tool temperatures on the component temperature, the sheet thickness distribution and process forces will be investigated. As a result, it has been demonstrated that mechanical, process-related and geometric advantages can be achieved by using locally temperature-controlled forming tools.