bluuebunny/crossref_metadata_2025 huggingface dataset:
ATEQ: Adaptive toroidal equilibrium code
Authors: Zheng Linjin , Kotschenreuther M. T. , Waelbroeck F. L. , Todo Y.
Published: July 2022

A radially adaptive numerical scheme is developed to solve the Grad–Shafranov equation for axisymmetric magnetohydrodynamic equilibrium. A decomposition with independent solutions is employed in the radial direction, and Fourier decomposition is used in the poloidal direction. The independent solutions are then obtained using an adaptive shooting scheme together with the multi-region matching technique in the radial direction. Accordingly, the adaptive toroidal equilibrium (ATEQ) code is constructed for axisymmetric equilibrium studies. The adaptive numerical scheme in the radial direction improves considerably the accuracy of the equilibrium solution. The decomposition with independent solutions effectively reduces the matrix size in solving the magnetohydrodynamic equilibrium problem. The reduction of the matrix size is about an order of magnitude as compared with the conventional radially grid-based numerical schemes. Also, in this ATEQ numerical scheme, no matter how accuracy in the radial direction is imposed, the size of matrices basically does not change. The small matrix size scheme gives ATEQ more flexibility to address the requirement of the number of Fourier components in the poloidal direction in tough equilibrium problems. These two unique features, the adaptive shooting and small matrix size, make ATEQ useful to improve tokamak equilibrium solutions.
Strong anharmonicity induced low lattice thermal conductivity and high thermoelectric performance in (CuInTe2)1−x(AgSbTe2)x system
Authors: Xiong Qihong , Yan Yanci , Li Nanhai , Zhang Bin , Zheng Sikang , Feng Yajie , Wang Guiwen , Liao Huijun , Huang Zhengyong , Li Jian , Wang Guoyu , Lu Xu , Zhou Xiaoyuan
Published: July 2022

The suppression of lattice thermal conductivity of thermoelectric CuInTe2 was often realized by complex micrometer-structure control. Herein, we demonstrate that simple alloying AgSbTe2 in CuInTe2 is capable of strongly strengthening lattice anharmonicity, which gives rise to an extremely low lattice thermal conductivity of ∼ 0.62 W m−1 K−1 at 823 K for (CuInTe2)0.95(AgSbTe2)0.05. In addition, the intentionally introduced copper vacancies can effectively increase the carrier concentration and dramatically improve the electrical performance of (CuInTe2)0.95(AgSbTe2)0.05. As a result, the sample with nominal composition of (Cu0.95InTe2)0.95(AgSbTe2)0.05 reaches a maximum zT value of ∼ 1.3 at 823 K. This study provides some insight into designing thermoelectric compounds in the diamond-like semiconductor family by inducing strong anharmonicity through a small amount of alloying.
2.9 K VCSEL demonstrates 100 Gbps PAM-4 optical data transmission
Authors: Wu Haonan , Fu Wenning , Wu Dufei , Feng Milton
Published: July 2022

A cryogenic packaged vertical-cavity-surface-emitting laser (VCSEL) with microwave input and coupled with OM4 fiber for optical output was developed and demonstrated laser operation from 295 to 2.9 K. Record 2.9 K optical data links of 100 Gbps pulsed amplitude modulation 4-level have been demonstrated with an energy per bit ∼153.4 fJ/bit when TDECQ = 3.79 dB. The energy/bit is limited by the link path bandwidth resulted from the input cable loss to 2.9 K VCSEL and can be further improved. Thus, the VCSEL optical data link is proven to be a viable solution for cryogenic communication and computing.
Anomalous Hall effect in nanoscale structures of the antiferromagnetic Weyl semimetal Mn3Sn at room temperature
Authors: Matsuo Takumi , Higo Tomoya , Nishio-Hamane Daisuke , Nakatsuji Satoru
Published: July 2022

The magnetic Weyl semimetallic state in the chiral antiferromagnet Mn3Sn has attracted interest for its potential in memory technology. Despite vanishingly small magnetization, the material exhibits large transverse responses that can be electrically manipulated, similar to ferromagnets. Through deposition on heated Si/SiO2 substrates, we have fabricated polycrystalline Mn3Sn films that have coarse surfaces, the thinner of which have a discontinuous structure comprised of grains with diameters of the order of 100 nm. We confirm that these grains retain the anomalous Hall effect arising in the time reversal symmetry broken chiral antiferromagnetic phase of Mn3Sn at room temperature by serially connecting the grains with an additional conducting layer. These results pave the path for the potential applications of nanoscale Mn3Sn systems, which could be useful in the development of energy efficient memory devices.
Quantitative analysis of fluid transport in dynamic stall of a pitching airfoil using variational Lagrangian coherent structures and lobe dynamics
Authors: Wang Wei , Zhang Jia-Zhong , Chen Zhi-Yu , Li Zhi-Hui
Published: July 2022

The evolution of flow structures during dynamic stall of a two-dimensional pitching National Advisory Committee for Aeronautics 0012 airfoil is studied using the variational Lagrangian coherent structures (LCSs), and the mass transport and vorticity transport are precisely analyzed using LCSs and lobe dynamics for further understanding the nature of flow phenomena in dynamic stall. First, the variational LCS algorithm is improved to be efficiently used in the accurate extraction of flow structures. Then, both the hyperbolic LCSs and elliptic LCSs are computed numerically in the whole process of dynamic stall to analyze the evolution of flow structures in detail. Further, a high-accuracy LCS-advection method is used in the advection of LCSs to quantitatively analyze the mass transport and vorticity transport in the evolution of LCSs utilizing lobe dynamics based on nonlinear dynamics. Finally, the evolution and motion of primary leading edge vortex (LEV) and trailing edge vortex (TEV) identified by elliptic LCSs are analyzed in depth. The results obtained can provide a deeper insight into the nature of flow phenomena in dynamic stall from the viewpoint of nonlinear dynamics. Specifically, the nature of evolution of primary LEV and the TEV and the reasons for the changes of lift coefficients are clarified from the viewpoint of fluid transport. To explain it briefly, the variational LCSs and lobe dynamics are powerful tools to quantitatively analyze the evolution of flow structures and fluid transport.
Evolution of the marker distribution in gyrokinetic δf particle-in-cell simulations
Authors: Chen Yang , Cheng Junyi , Parker Scott E.
Published: July 2022

The evolution of the particle weight in a δf particle-in-cell simulation depends on the marker distribution that can evolve in a turbulent field due to turbulent diffusion. When Monte Carlo methods are used to implement the test particle collision operator, or when the particle motion is not strictly Hamiltonian in a collisionless simulation, the marker distribution will evolve along the particle trajectory and, in general, cannot be known exactly. A two-dimensional numerical marker distribution is proposed as an approximation. It is shown to be advantageous over other common methods for evaluating the marker distribution in long-time turbulence simulations. A generalized two-weight δf-method is proposed to mitigate the marker evolution problem.
The electrons' journey in thick metal oxides
Authors: Caruso Francesco , La Torraca Paolo , Larcher Luca , Tallarida Graziella , Spiga Sabina
Published: July 2022

Originally introduced in electronic manufacturing to replace the SiO2 insulating layer, metal oxides are now extensively used in a multitude of electronic devices. Understanding charge transport mechanisms in metal oxides is of paramount importance for device optimization; however, a detailed and self-consistent discussion of electron conduction at all applied electric fields is lacking in the literature. In this work, we investigated the conduction mechanisms in three model systems, Al2O3, HfO2, and Al-doped HfO2 metal–insulator–metal capacitors, determining the path that the electrons travel within the metal oxide. Traps properties are extracted from experimental current–voltage characteristics using the Ginestra® simulation software. Furthermore, the analysis allowed to visualize the location of traps most involved in the conduction and the dominant transport mechanisms at each applied electric field. Despite the different oxide properties, a similar trend was recognized at low electric fields, the electron transport through the oxide is negligible, and the dominant contribution to the measured current is ascribed to the charge/discharge of traps located near the metal/oxide interfaces, leading to displacement currents. At high electric fields, the transport of electrons occurs through the defect rich oxides in the two following ways: if a large density of traps is energetically located near the electrodes Fermi level (as in HfO2), the electrons tunnel from trap to trap until they reach the anode; otherwise, when traps are closer to the conduction band (as in Al2O3 and AlHfO), the electrons tunnel from the cathode into one trap and then into the oxide conduction band, interacting only with traps near the cathode.
Electron affinity of tantalum and excited states of its anion
Authors: Li Sheng , Fu Xiaoxi , Chen Xiaolin , Lu Yuzhu , Ning Chuangang
Published: July 2022

The tantalum anion has the most complicated photoelectron spectrum among all atomic anions of transition elements, which was the main obstacle to accurately measure its electron affinity via the generic method. The latest experimental value of the electron affinity of Ta was 0.323(12) eV, reported by Feigerle et al. [J. Chem. Phys. 74, 1580 (1981)]. In the present work, we report the high-resolution photoelectron spectroscopy of Ta− via the slow-electron velocity-map imaging method combined with a cryogenic ion trap. The electron affinity of Ta was measured to be 2652.38(17) cm−1 or 0.328 859(23) eV. Three excited states 5D1, 3P0, and 5D2 of Ta− were observed, and their energy levels were determined to be 1169.64(17) cm−1 for 5D1, 1735.9(10) cm−1 for 3P0, and 2320.1(20) cm−1 for 5D2 above the ground state 5D0, respectively.
Fifty-year review: European rabbit fleas,
Authors: Cooke Brian D.
Published: July 2022

European rabbit fleas were released among Australian wild rabbits in the late 1960s to supplement mosquitoes as vectors of myxoma virus. Data from study sites across southern Australia in the 1960s and 1970s are reviewed to discern common elements of flea-borne myxomatosis epizootics and a simple model is proposed to explain how virus virulence and food quality interact to determine rabbit abundance. Low, stable populations of rabbits implied that, despite virus attenuation and increased rabbit disease resistance, flea-borne myxomatosis was extremely important in controlling rabbit populations. Despite the enhancement of myxomatosis, livestock producers benefitted little from the additional pasture because marketing difficulties were not conducive to industry growth. Native wildlife likely benefitted, nonetheless.
Experimental evidence of physician social preferences
Authors: Li Jing , Casalino Lawrence P. , Fisman Raymond , Kariv Shachar , Markovits Daniel
Published: July 2022

Physicians’ professional ethics require that they put patients’ interests ahead of their own and that they should allocate limited medical resources efficiently. Understanding physicians’ extent of adherence to these principles requires understanding the social preferences that lie behind them. These social preferences may be divided into two qualitatively different trade-offs: the trade-off between self and other (altruism) and the trade-off between reducing differences in payoffs (equality) and increasing total payoffs (efficiency). We experimentally measure social preferences among a nationwide sample of practicing physicians in the United States. Our design allows us to distinguish empirically between altruism and equality–efficiency orientation and to accurately measure both trade-offs at the level of the individual subject. We further compare the experimentally measured social preferences of physicians with those of a representative sample of Americans, an “elite” subsample of Americans, and a nationwide sample of medical students. We find that physicians’ altruism stands out. Although most physicians place a greater weight on self than on other, the share of physicians who place a greater weight on other than on self is twice as large as for all other samples—32% as compared with 15 to 17%. Subjects in the general population are the closest to physicians in terms of altruism. The higher altruism among physicians compared with the other samples cannot be explained by income or age differences. By contrast, physicians’ preferences regarding equality–efficiency orientation are not meaningfully different from those of the general sample and elite subsample and are less efficiency oriented than medical students.
Unifying the order and disorder dynamics in photoexcited VO2
Authors: Liu Hao-Wen , Liu Wen-Hao , Suo Zhao-Jun , Wang Zhi , Luo Jun-Wei , Li Shu-Shen , Wang Lin-Wang
Published: July 2022

Photoinduced phase transition (PIPT) is always treated as a coherent process, but ultrafast disordering in PIPT is observed in recent experiments. Utilizing the real-time time-dependent density functional theory method, here we track the motion of individual vanadium (V) ions during PIPT in VO2and uncover that their coherent or disordered dynamics can be manipulated by tuning the laser fluence. We find that the photoexcited holes generate a force on each V–V dimer to drive their collective coherent motion, in competing with the thermal-induced vibrations. If the laser fluence is so weak that the photoexcited hole density is too low to drive the phase transition alone, the PIPT is a disordered process due to the interference of thermal phonons. We also reveal that the photoexcited holes populated by the V–V dimerized bonding states will become saturated if the laser fluence is too strong, limiting the timescale of photoinduced phase transition.
The importance of elders: Extending Hamilton’s force of selection to include intergenerational transfers
Authors: Davison Raziel , Gurven Michael
Published: July 2022

In classical evolutionary models, the force of natural selection diminishes with age toward zero by last reproduction. However, intergenerational resource transfers and other late-life contributions in social species may select for postreproductive longevity. We present a formal framework for estimating indirect fitness contributions via production transfers in a skills-intensive foraging niche, reflecting kinship and cooperation among group members. Among contemporary human hunter-gatherers and horticulturalists, indirect fitness contributions from transfers exceed direct reproductive contributions from before menopause until ages when surpluses end, around the modal age of adult death (∼70 y). Under reasonable assumptions, these benefits are the equivalent to having up to several more offspring after age 50. Despite early independence, minimal production surplus, and a shorter lifespan, chimpanzees could theoretically make indirect contributions if they adopted reliable food-sharing practices. Our results for chimpanzees hypothetically adopting hunter-gatherer subsistence suggest that a skills-intensive foraging ecology with late independence and late peak production could select for human-like life histories via positive feedback between longevity and late-life transfers. In contrast, life history changes preceding subsistence shifts would not favor further life extension or subsistence shifts. Our results formalize the theory that longevity can be favored under socioecological conditions characterized by parental and alloparental care funded through transfers of mid- to late-life production surpluses. We also extend our analysis beyond food transfers to illustrate the potential for indirect fitness contributions from pedagogy, or information transfers. While we focus mostly on humans, our approach is adaptable to any context or species where transfers can affect fitness.
A Cognitive Grammar approach to ‘metonymy’
Authors: Broccias Cristiano
Published: July 2022

This chapter builds on Broccias’s (2017) critique of recent cognitive linguistic approaches to metonymy, which tend to neglect form and the substitutive relation built into the traditional x for y formula. By bringing back to the fore the tropical characterization of metonymy (Matzner 2016), which instead relies heavily on form and abrasiveness, this chapter develops a Cognitive Grammar approach to metonymy which rests on the reference point ability and conceptual integration. It shows how this approach can handle a variety of cases, from ‘straightforward’ metonymies to ‘metonymic association’. Crucially, it is argued that the multifaceted examples taken into consideration do not necessarily cohere into a ‘Platonic’ category.
Reconsidering accounts of the grammaticalization of auxiliaries
Authors: Polzenhagen Frank
Published: July 2022

The present paper re-addresses two standard examples of grammaticalization research, i.e. the development of the be-going-to form and the evolution of the English have-perfect. Analyzing these two forms in communion is motivated by the fact that they express conceptual patterns that are mirror images of each other and by the observation that they have developed, historically speaking, largely in an in-tandem constellation. The specific perspective taken in the paper explores several dimensions of the broader conceptual context of their auxiliation: (i) the “lexical preface” of grammaticalization processes, (ii) conceptual patterns associated with the notions that constitute the “meaning” of the respective forms, and (iii) the interaction with the development of other items in the respective domains. These aspects have received only scarce attention in grammaticalization research.
Draining the swamp
Authors: Berberović Sanja , Džanić Nihada Delibegović
Published: July 2022

This chapter examines the use of the expression to drain the swamp, whose meaning is created in conceptual blending, and the creative figurative language produced by the elaboration, modification, and reinterpretation of the blend itself in the contemporary American political discourse. This paper aims to show that creative figurative language can be used in different ways by members of a discourse community to achieve various rhetorical goals and discourse coherence. Specifically, applying conceptual blending theory, this paper analyzes innovative conceptual blends used to keep political discussions alive and be rhetorically effective. In addition, such creative blends also provide discourse coherence at the intertextual level.
Predicted Pressure-Induced High-Energy-Density Iron Pentazolate Salts
Authors: Sun Chuli , Guo Wei , Yao Yugui
Published: July 2022

Metal-pentazolate compounds as candidates for novel high-energy-density materials have attracted extensive attention in recent years. However, dehydrated pentazolate salts of transition metal iron are rarely reported. We predict two new iron pentazolate salts Fdd2-FeN10 and

P

1
¯

(No.1)-FeN10 using a constrained crystal search method based on first-principles calculations. We propose that the stable Fdd2-FeN10 crystal may be synthesized from FeN and N2 above 20 GPa, and its formation enthalpy is lower than the reported iron pentazolate salt (marked as

P

1
¯

(No.2)-FeN10). Crystal

P

1
¯

(No.1)-FeN10 is composed of iron bispentazole molecules. Formation enthalpy, phonon spectrum and ab initio molecular dynamics calculations are performed to show their thermodynamic, mechanical and dynamic properties. Moreover, the high energy density (3.709 kJ/g, 6.349 kJ/g) and good explosive performance indicate their potential applications as high-energy-density materials.
ECEI characterization of pedestal fluctuations in quiescent H-mode plasmas in DIII-D
Authors: Yu Guanying , Nazikian Raffi , Zhu Yilun , Zheng Yuan , Kramer Gerrit , Diallo Ahmed , Li Zeyu , Chen Xi , Ernst Darin , Zheng Yan , Austin Max , Luhmann Jr N C
Published: July 2022

Electron cyclotron emission imaging (ECEI) is employed to characterize the magneto hydraulics dynamics (MHD) fluctuations at the quiescent H-mode pedestals in DIII-D. Pedestal MHD fluctuations cause ECE radiation temperature fluctuations

δ

T

e

,rad

in both the pedestal and scrape-off-layer (SOL). A synthetic ECE platform is utilized for detailed interpretation of the ECEI signals in the SOL and pedestal regions. It is observed that the ECE radiation

δ

T

e

,rad

, which is located in the SOL region according to the cold and optically thick plasma resonance assumption, is extremely sensitive to MHD radial displacements near the separatrix, exhibiting radiation inversion to

δ

T

e

,rad

at the pedestal. Here, the radiation inversion refers to the opposite phase between the radiation fluctuation at the pedestal and the radiation fluctuation at the SOL. Consequently, the quasi-coherent MHD (QCM), which displays a radiation inversion, is found to be consistent with an MHD radial structure that has a strong displacement near the separatrix. In contrast, the edge harmonic oscillation (EHO), which displays weak or no inversion, is found to be consistent with an MHD radial displacement structure peaking at the pedestal top. The ECEI data, interpreted with synthetic ECE, are in qualitative agreement with beam emission spectroscopy measurements on DIII-D for the relative radial extent and localization of the EHO and QCM. The high sensitivity of ECE radiation to separatrix displacements can be used to detect turbulence or MHD fluctuations near the separatrix, which may affect the transport across the separatrix and the wetted area in the divertor. The

δ

T

e

,rad

inversion measured with an ECE or ECEI system potentially provides important information on the magnetic field

B

sep

at the separatrix, which helps constrain the pedestal equilibrium reconstruction and achieve an unambiguous mapping of the ECE/ECEI system with respect to the separatrix.
Evolutions of repetitively pulsed positive streamer discharge in electronegative gas mixtures at high pressure
Authors: Zhao Zheng , Huang Zongze , Zheng Xinlei , Li Chenjie , Sun Anbang , Li Jiangtao
Published: July 2022

Electronegative gas components and gas pressure significantly change residual charge dynamics, which are critical for pulse-periodic streamer discharge behaviors. Evolutions of repetitively pulsed positive streamer discharge and the streamer-to-spark transitions were investigated at high pressures and compared between typical weak (O2) and strong (SF6) electronegative gas mixtures. Pulse-sequence resolved electrical and optical diagnostics were implemented to capture discharge evolutions in long pulse trains. We observe that streamer inception and propagation under subsequent pulses in N2 and N2–O2 mixtures are similar, including the earlier inception of the primary streamer and the accelerated propagation of the secondary streamer. The repetitively pulsed breakdown is extended to the low pulse repetition frequency region with the addition of O2. Discharge evolutions are unexpectedly different in N2–SF6 mixtures. Subsequent discharge channels prefer to propagate around the periphery of the inception cloud region with large radial deviations. Another difference is the precursor channel identified besides multiple streamer channels. Effects of electronegative gas on streamer evolutions under positive repetitive pulses have been qualitatively analyzed. Collisional electron detachment and photo-ionization are crucial in N2–O2 mixtures. With the presence of strong electronegative gas (SF6), the leader formation is probably induced by the earlier corona inception and longer voltage stressing period under following pulses in a pulse train, which are caused by the strong electronegativity of SF6 and the small ion mobility.
Enhancing the excitation of a high-index nanowire by adding a flat-ended head
Authors: Zhou Song , Zhou Wenchao
Published: July 2022

A method for enhancing the excitation of a high-index nanowire with an added flat-ended head is numerically investigated. With the assistant of a flat-ended head, the intensity and the power flow of the high-index nanowire illuminated under a plane wave can be both enhanced. Our simulation shows that the enhancement factor is influenced by the length and the refractive index of the nanowire, and the size of the flat-ended head. The enhanced excitation of a silicon nanowire under a near-infrared illumination by an added flat-ended head is studied. Finally, the enhanced excitation affected by the incident angle is discussed.
Cross-field and parallel dynamics of SOL filaments in TCV
Authors: Offeddu N. , Han W. , Theiler C. , Golfinopoulos T. , Terry J.L. , Marmar E. , Wüthrich C. , Tsui C.K. , de Oliveira H. , Duval B.P. , Galassi D. , Oliveira D.S. , Mancini D. , the TCV Team
Published: July 2022

Using recently installed scrape-off layer diagnostics on the tokamak à configuration variable, we characterise the poloidal and parallel properties of turbulent filaments. We access both attached and detached divertor conditions across a wide range of core densities (f
G ∈ [0.09, 0.66]) in diverted L-mode plasma configurations. With a gas puff imaging (GPI) diagnostic at the outer midplane we observed filaments with a monotonic increase in radial velocity (from 390 m s−1 to 800 m s−1) and cross-field radii (from 8.5 mm to 13.4 mm) with increasing core density. Interpreting the filament behaviour in the context of the two-region model by Myra et al (2006 Phys. Plasmas
13 112502), we find that they populate the ideal-interchange regime (C
i) in discharges at very low densities, and the resistive X (RX)-point regime for all other discharges. The scaling of filament velocity versus size shows good agreement with this interpretation. These results are discussed and compared with previous probe-based measurements for similar conditions, which mostly placed filaments in TCV in the resistive ballooning (RB) regime (Tsui et al 2018 Phys. Plasmas
25 072506). In addition, for the first time in TCV, the parallel filament extension is studied by magnetically aligning the GPI measurements at the outboard midplane with a reciprocating probe in the divertor. In agreement with the filaments being in the ideal-interchange and the RX-point regimes, they are found to extend beyond the X-point into the outer divertor leg.
Study on induced aeration for fishery fields using floating SPV
Authors: Muramulla Sai Mounika , Rajeshwari Rangampeta , Rejina Parvin J , Anand chakaravarthi M C , Janardhana Kedri , Bhattacharya Sumanta
Published: July 2022

The soluble oxygen content in the water is affected by oxygenation, which is a vital factor for commercial fishery fields. The soluble oxygen content is the prime factor for the fishes grown in those fields, and most probably, the fields are located in remote locations where electricity could not be accessible. Photovoltaics (PVs) are becoming more popular as a renewable resource. The electric power generated by solar panels can be utilized to run the aerators in order to aerate the fishery fields that are isolated and disconnected from the primary power system. A 100 Wp floater solar PV (SPV) modules for powering five numbers of DC aerators are used in the present investigation. The efficiency of floated solar panels was monitored by measuring sun irradiation, PV temperatures, output power, and current. The amount of oxygen in the water before aeration was around 3.2 mg/L, however after deploying floated solar panels and aerator, the level of soluble oxygen was raised to 4.4 mg/L.
Investigation of the effect of electron beam parameters on the characteristics of the steam-gas channel during welding of nickel and titanium alloys
Authors: Goncharov A L , Sliva A P , Chulkov I S , Chulkova A V , Kharitonov I A
Published: July 2022

The article presents the developed technique of high-speed video recording of the combined-cycle gas channel and subsequent frame processing to obtain the dimensional characteristics of the combined-cycle gas channel. On the basis of this technique, dependences of the width of the weld at different depths were obtained depending on the current and welding speed. A pattern of dimensional characteristics of the steam-gas channel depending on the running energy and the dependence of the frequency of collapse of the steam-gas channel on the electron beam current at a constant welding speed of 40 m/h by the example of nickel and titanium alloys was revealed.
Penetration shape control with correction of the state variables evaluation during electron-beam welding by the level of active disturbances
Authors: Lastovirya V N , Rodyakina R V
Published: July 2022

Penetration shape during electron-beam welding is determined in the first approximation by the vapour plasma crater shape formed by the energy source. The inability to measure the parameters of penetration shape during electron-beam welding leads to their estimation by regression equations that establish a relationship with mode parameters. However, when welding mode parameters are stabilized, the instability of penetration shape remains due to the action of uncontrolled disturbances, which in some cases lead to unacceptable deviations. A possibility of the state variables evaluation correction during electron-beam welding, namely the depth penetration and the weld shape factor, by determining the “noise component”, is considered. Such correction is carried out by the discrepancy of any measured output variable, as the difference between its estimate according to a similar mathematical model and the measured value. As such output variable, the vapour plasma torch light intensity can be used. A control algorithm and a structural diagram of the automatic control system for weld penetration shape with correction of model assessment of the process state by the measured output have been developed.
Influence of thermal aging modes on mechanical properties of steel welded joint 03N18K9M5T
Authors: Santalova Yu V , Terentyev E V , Yu Marchenkov A , Gudenko A V , Borodavkina K T , Kozyrev Kh M
Published: July 2022

The article presents results of research of the influence of the modes of thermal aging, namely temperature of aging and hold time, on mechanical properties of a weld joint from maraging steel 03H18K9M5T. Aging curves were constructed, that is, the hardness of the metal under study versus the holding time at certain temperatures. Based on the results obtained, an optimal thermal aging regime was proposed for all areas of the welded joint, after which the welded joints were heat-treated by aging in optimal conditions. Hardness distributions were built over the section of the welded joint of martensitic-aging steel samples. Metallographic studies were carried out on the weld microspheres.
A systematic construction of integrable delay-difference and delay-differential analogues of soliton equations
Authors: Nakata Kenta , Maruno Ken-ichi
Published: July 2022

We propose a systematic method for constructing integrable delay-difference and delay-differential analogues of known soliton equations such as the Lotka–Volterra, Toda lattice (TL), and sine-Gordon equations and their multi-soliton solutions. It is carried out by applying a reduction and delay-differential limit to the discrete KP or discrete two-dimensional TL equations. Each of the delay-difference and delay-differential equations has the N-soliton solution, which depends on the delay parameter and converges to an N-soliton solution of a known soliton equation as the delay parameter approaches 0.
Dynamic Fingerprint Benchmarking Model for WiFi Indoor Localization
Authors: Aljeroudi Yazan , Sulaeman Erwin , Legowo Ari
Published: July 2022

WiFi indoor localization is regarded as the most promising reliable technology for indoor localization. Its concept is based on building fingerprint and training a ma-chine learning model on it, then using it for predicting the location based on the measured received signal strength RSS. One aspect of its vulnerability is its time vari-ant change due to the dynamical conditions in the environment and the access points APs. This was the most focus of the researchers in the last decades. However, minori-ty of them have considered the limitations of the existing benchmarking fingerprint in terms of lacking of support to realistic navigations runs when they are used for eval-uating indoor localization models. This article proposes a simple yet novel add-on to existing benchmarking fingerprint that assists in converting it from static fingerprint to consecutive training data with supportability to incremental learning and awareness of various characteristics of indoor navigation runs. The model was evaluated based on two benchmarking fingerprint and the generated incremental data were plotted with two levels of granularity one is corresponding to location and the other to place for referring to high resolution level and low resolution level.
Frictional Power Evaluation of Additive-Mixture in Trimethylolpropane Trioleate Oil using Single Cylinder Diesel Engine
Authors: Syahir A. Z. , Masjuki H. H. , Yusoff M. N. A. M. , Ibrahim T. M.
Published: July 2022

Rapid depletion of petroleum sources and increase of demand for environmentally friendly products has urged the need for biodegradable lubricants to be utilized in various applications, especially for internal combustion (IC) engine lubrication. To perform on par with the commercial engine oils, bio-based lubricants need to be further improved through the addition of appropriate additives. This study investigates the synergistic performance of additive-mixture comprising of ionic liquids (IL), glycerol monooleate (GMO), molybdenum dithiocarbamate (MoDTC) and titanium dioxide (TiO2) nanoparticle in trimethylolpropane trioleate (TMPTO) ester base oil. Lubricity performances of the prepared sample were evaluated in the context of tribological improvement using laboratory tribotester as well as friction power reduction in actual single-cylinder diesel engine. From a prior study, it was found that additive mixture containing 0.93 wt.% IL, 1.49 wt.% GMO, 0.52 wt.% MoDTC, and 1.25wt.% TiO2 was able to provide substantial friction and wear as well as extreme pressure improvements. The present study was conducted to evaluate whether the formulation can offer the same performance on the actual engine in conjunction to the laboratory bench test. To do so, two different types of engine tests were conducted which are that standard engine performance test and also the Willans line test to evaluate the engine frictional power. The performance of the additives-TMPTO mixture was compared directly to those of commercial SAE 0W-30 engine lubricant. In the standard engine performance test, it was found that the additives-TMPTO mixture performed better than commercial SAE 0W-30 engine lubricant in terms of 2.5% higher maximum torque value, 3% higher overall brake power output, 10% lower brake specific fuel consumption and 12% higher brake thermal efficiency throughout the conducted test speed of 800 to 2300 rpm. Through the Willans line test, it was found that the additives-TMPTO mixture showed better results than the commercial SAE 0W-30 engine lubricant in terms of 20-25% lower frictional power at 900, 1200 and 1500 rpm. Overall, these results further justify the enhanced lubrication properties of the formulated bio-based oil in addition to the prior conducted tribological analyses.
Numerical simulation of axially impacted elastic bar
Authors: Hamdani A. , Pankaj P.
Published: July 2022

This numerical analysis considers a model of an elastic cylindrical bar impacted by rigid mass, where the accuracy of the model is benchmarked by a closed-form solution developed for this impact process. The analytical solution provides theoretical background and understanding, however, practical problem is not always restricted to a simple one-dimensional geometry and boundary conditions of a purely elastic material behaviour. Hence, the current work numerically simulates the impacted elastic bar, then explores parameters which are not considered in its theoretical model. A two-dimensional (2D) solid axisymmetric system is considered, in which rigid impactor is assigned with initial velocity corresponding to certain drop height and a 2D contact type is defined between interacting bodies. Both elastic and time-dependent viscoelastic material models are considered in this study. The simulation results reveal time intervals gradually increase in every sequential intervals, while relatively small discrepancies are recorded for peak load and pulse width outputs. The parameters of impactor’s mass, drop height and structural stiffness are varied; showing how these parameters individually affect the resulting force response at end struck. The models then evaluate time-dependent viscoelastic material model; showing stiffer response of the resulting force in comparison to models assigned with long-term elastic moduli. Derived elastic modulus-output variable relations show comparable mathematical forms to corresponding equations formulated analytically.
An investigation on structural dynamic modification of a machine casing
Authors: Hanouf Zahir , Abdelrahman Ahmed , Ahmad Kartini
Published: July 2022

Investigation on structural dynamic characteristic is a crucial step in the noise, vibration and harshness (NVH) analysis in order to enhance the structural vibration, which subsequently contribute to improving the acoustical environment. The excitation of the structure can produce high vibration which could be transferred to the other parts of the body, then lead to high noise radiating components. Structural dynamic modification is one of the important techniques in the design of mechanical structures. It is an application of experimental modal analysis technique to investigate the effect of the physical and geometrical parameters on the dynamic properties of the structures such as frequencies and mode shapes. This paper investigates the dynamic properties of a machine casing structure which is extensively used in industrial applications. This investigation had successfully produced natural frequencies and their associated mode shapes of such open box for the original structure and modified structure. The study establishes the step-by-step procedures to carry out experimental modal analysis on the structures, using single input excitation and single output responses (SISO) technique. To ensure the validity of the results obtained an inverse method was done by fixing the response and moving the excitation. The results found were absolutely the same. Finally, comparison between results obtained from analysis showed significant differences on both frequencies and mode shapes.
The Effect of Cutting Speeds on Tool Wear and Surface Roughness when Milling Carbon Fiber Reinforced Polymer
Authors: Mustafa Aisyah Madihah , Shahruddin Najlah Sakinah , Halim Nor Farah Huda Abdul , Rozhan Alya Naili , Hattiar Maziati Akmal
Published: July 2022

Carbon fibre reinforced polymeric material (CFRP) is increasingly being used to replace metallic materials, particularly in the automobile and aerospace industries. The mechanical properties of the CFRP such as excellent weight to strength ratio give beneficial outcome in improving the performance of the part made from CFRP. However, machining of CFRP such as milling is difficult and challenging due to the abrasiveness of the CFRP. Therefore, the influence of cutting speeds on tool wear and surface roughness when milling CFRP in a dry condition is the aim of this paper. The milling test was carried out using 6 mm WC-Co end mill tool having 30° helix angle. Milling of CFRP was performed with three different cutting speeds, Vc
(94, 113 and 132 m/min) while feed rate, f (1800 mm/min) and radial depth of cut, ae
(2 mm) were remained constant. Milling CFRP with Vc
=132 m/min resulted in increasing of tool wear by 15 % and increasing of surface roughness by 10% when compared with Vc
= 94 m/min. CFRP surface damages such as matrix smearing, delamination and fibre pull out was observed when milling with higher cutting speed.
Effect of process parameters on the laser microdrilling performance of stainless steel, aluminium and copper
Authors: Noor W. , Saleh T. , Rashid M. A. N. , Ibrahim A. M.
Published: July 2022

Micromachining techniques are being used regularly in various engineering and production sectors such as Micro Electromechanical Systems, Aerospace, Automotive, Electronics and Biomedical industries. For Laser Beam Micromachining, highly energized laser beam is focused on a small region of the workpiece surface. As a result, it is heated up rapidly to sufficiently high temperatures, then the material starts to melt and/or vaporize from the surface. This phenomenon of material removal is called laser ablation. The holes that are produced by one-dimensional laser beam drilling (LBD) can come with defects like taper, heat affected zone (HAZ) and Recast Layer. On the other hand, LBD process offers high control, high efficiency, precision, and production rate, particularly for drilling microscopic holes in a variety of materials. LBD performance is measured on different parameters such as taper and recast layer of the machined holes. Previous studies report many observations regarding the performance parameters and the process input parameters. But a thorough study of the performance parameters with respect to different material properties has not been reported yet. The research work for this paper focuses on the experimental investigation for different materials such as stainless steel (type SS304), Aluminum and Copper to observe the effects of Laser input parameters (namely laser power, scanning speed, and pulse repetition rate) on the performance of the LBD. The study also considers different thermophysical as well as optical properties such as thermal conductivity, specific heat, melting point, absorptivity and how it affects the outcome of LBD in a combined manner. Characterization of different output parameters such as Entry area, Exit Area and Recast Area is done by SEM (Scanning Electron Microscope) machine. For 75 Loop count, 90% Laser Power, 950 mm/s Scanning Speed and 10kHz pulse repetition rate, the highest amount of Recast Area is observed in SS, valued at 0.053 mm2. The largest amount of taperness is found in Cu at 44.404°. Scanning Speed and Laser Power has been identified as the most significant process factors for LBD performance.
Design of a versatile microfluidic device for imaging precision-cut-tissue slices
Authors: Rafiei Nafiseh , Moghadam Mohammadamir G , Au Aaron , Regeenes Romario , Chidambaram Subbulakshmi , Liang Tao , Wang Yufeng , Yip Christopher M , Gaisano Herbert , Rocheleau Jonathan V
Published: July 2022

Precision-cut-tissues (PCTs), which preserve many aspects of a tissue’s microenvironment, are typically imaged using conventional sample dishes and chambers. These can require large amounts of reagent and, when used for flow-through experiments, the shear forces applied on the tissues are often ill-defined. Their physical design also makes it difficult to image large volumes and repetitively image smaller regions of interest in the living slice. We report here on the design of a versatile microfluidic device capable of holding mouse or human pancreas PCTs for 3D fluorescence imaging using confocal and selective plane illumination microscopy (SPIM). Our design positions PCTs within a 5 × 5 mm × 140 µm deep chamber fitted with 150 µm tall channels to facilitate media exchange. Shear stress in the device is localized to small regions on the surface of the tissue and can be easily controlled. This design allows for media exchange at flowrates ∼10-fold lower than those required for conventional chambers. Finally, this design allows for imaging the same immunofluorescently labeled PCT with high resolution on a confocal and with large field of view on a SPIM, without adversely affecting image quality.
Influence of the thickness of the copper glaze layer on the color and its formation mechanism
Authors: Wang Chao , Liu Kun , Chen Xin , Shi Wei , Li Xiaohong , Wang Shaohua , Chang Qibing , Wang Yongqing , Wang Qikun
Published: July 2022

In this paper, the effects of glaze layer thickness on the color properties of copper glaze were investigated, and the related mechanism was also revealed. The results manifest that the glaze thickness would affect the color of copper glaze. The color properties of copper glaze are determined by the phase-separated structure, the distribution of elements and the valence state of copper species. Due to the heterogeneous distribution behavior of the elements, the copper glazes with all thicknesses have three phase-separated structures, which are spherical (top layer), worm-like (interlayer) and nano-porous network-like (bottom layer). Simultaneously, the copper glazes with all thicknesses have three colors, of which the bottom layer of all samples is red. However, the color of the top layer gradually changes from milk white (0.2 mm) to cyan (0.4–0.6 mm) and then to blue (0.8–1.0 mm) with the green body thickness increases. The color of interlayer is the result of the color mixing of the top and bottom layer. A thicker green body thickness (>1 mm) could be propitious for copper glaze to present a superior color performance. This work provides a new and an easily overlooked perspective for the investigation of copper glaze.
Effect of ZnO nanoparticle content on the amorphousness of conducting jackfruit seed starch-PVA blend polymer electrolyte
Authors: Raihan R , Fairuzdzah A L , Asiah M N , Ali A M M
Published: July 2022

Nanocomposite polymer electrolyte films based on a blend of two polymers jackfruit seed starch (JSS) and poly (vinyl alcohol) (PVA) complexed with nano-particle zinc oxide (ZnO) (i.e., (50 wt% JSS/50 wt% PVA) + x wt% ZnO where x = 0, 2, 4, 6, 8, 10, 12 and 14) were prepared by using the casting solution method. Electrochemical impedance spectroscopy (EIS) has been employed between the frequencies of 10 Hz and 1 MHz to get the optimum values of the conductivity of the prepared polymer electrolyte films. The effect of ZnO nano-filler concentration on the chemical bonding, crystallinity, morphology, and ionic conductivity has been studied. The maximum ionic conductivity at ambient temperature of 1.10 × 10–6S cm−1was obtained for (50 wt% JSS/50 wt% PVA) + 10 wt% ZnO JSS-PVA blend film and it is attributed to the highest amorphous content.
Functionality-switchable terahertz metamaterial with perfect absorption and circular dichroism
Authors: Liang Shuang , Zhu Zebin , Jiang Liyong
Published: July 2022

Terahertz functionality-switchable devices have drawn more and more attention in the past few years. Here we report a graphene-VO2 based planar terahertz metamaterial model which can support switchable functions between perfect absorption and circular dichroism (CD) by changing the phase of VO2. In particular, when VO2 is in the metal phase or insulator phase, the device can respectively work as a broadband perfect absorber with maximum absorption larger than 99% or an absorber with a CD value as high as about 0.5 for the left-handed polarized and right-handed polarized beams. We employ the coherent light absorption theory and mode coupling model of the U-shaped resonators to interpret the underlying mechanism of the device. Meanwhile, the performance of the device can be modulated on purpose by changing the chemical potential of graphene or the thickness of the SiO2 spacer layer.