bluuebunny/crossref_metadata_2025 huggingface dataset:
Sustainable high-pressure light-driven water pump with a spiral tube structure and Büttiker–Landauer ratchet
Authors: Sugioka Hideyuki , Yoshijima Hiroki
Published: October 2022

Developing sustainable water transportation technology is essential for solving water shortage problems. In this study, we proposed a sustainable high-pressure light-driven water pump that used a spiral tube structure (where light hit one side and shadowed the other) with a Büttiker–Landauer (BL) ratchet. Moreover, we examined the performance of this water pump. By using a polyurethane tube with a diameter of 2.5 mm and a length of 5 m, we demonstrated that the light-driven BL pump lifted water from a water source against the force of gravity, transported it horizontally along the spiral tube, and removed it from the tube against the surface tension. In particular, by the height scale-up design, we observed ∼800 times larger actual pressure difference (ΔP∼40 Pa) than the previous light-driven BL pump along with the pumping flow velocity up to 2.4 mm/s. In addition, by proposing a model that considers the effect of the transportation of heat energy from the hot region to the cold region, we explain the experimentally observed self-adjustment phenomenon for a flow velocity. Since our pump can work under sunlight without using electricity or fossil fuels, it is more sustainable than other pumps. Our findings should contribute to practical sustainable water transportation.
Validation and parameterization of a novel physics-constrained neural dynamics model applied to turbulent fluid flow
Authors: Shankar Varun , Portwood Gavin D. , Mohan Arvind T. , Mitra Peetak P. , Krishnamurthy Dilip , Rackauckas Christopher , Wilson Lucas A. , Schmidt David P. , Viswanathan Venkatasubramanian
Published: October 2022

In fluid physics, data-driven models to enhance or accelerate time to solution are becoming increasingly popular for many application domains, such as alternatives to turbulence closures, system surrogates, or for new physics discovery. In the context of reduced order models of high-dimensional time-dependent fluid systems, machine learning methods grant the benefit of automated learning from data, but the burden of a model lies on its reduced-order representation of both the fluid state and physical dynamics. In this work, we build a physics-constrained, data-driven reduced order model for Navier–Stokes equations to approximate spatiotemporal fluid dynamics in the canonical case of isotropic turbulence in a triply periodic box. The model design choices mimic numerical and physical constraints by, for example, implicitly enforcing the incompressibility constraint and utilizing continuous neural ordinary differential equations for tracking the evolution of the governing differential equation. We demonstrate this technique on a three-dimensional, moderate Reynolds number turbulent fluid flow. In assessing the statistical quality and characteristics of the machine-learned model through rigorous diagnostic tests, we find that our model is capable of reconstructing the dynamics of the flow over large integral timescales, favoring accuracy at the larger length scales. More significantly, comprehensive diagnostics suggest that physically interpretable model parameters, corresponding to the representations of the fluid state and dynamics, have attributable and quantifiable impact on the quality of the model predictions and computational complexity.
Tuning the p-type doping of GaN over three orders of magnitude via efficient Mg doping during halide vapor phase epitaxy
Authors: Ohnishi Kazuki , Fujimoto Naoki , Nitta Shugo , Watanabe Hirotaka , Lu Shun , Deki Manato , Honda Yoshio , Amano Hiroshi
Published: October 2022

The precise control of Mg concentration ([Mg]) in p-type GaN layers from 2.3 × 1016 to 2.0 × 1019 cm−3 was demonstrated by halide vapor phase epitaxy (HVPE) on n-type GaN (0001) freestanding substrates. [Mg] in GaN layers could be controlled well by varying the input partial pressure of MgCl2 formed by a chemical reaction between MgO solid and HCl gas under the thermodynamic equilibrium condition. In the sample with [Mg] of 2.0 × 1019 cm−3, a step-bunched surface was observed because the surface migration of Ga adatoms was enhanced by the surfactant effect of Mg atoms. The samples show high structural qualities determined from x-ray rocking curve measurements. The acceptor concentration was in good agreement with [Mg], indicating that almost all Mg atoms act as acceptors. The compensating donor concentrations in the samples were higher than the concentrations of Si, O, and C impurities. We also obtained the Mg acceptor level at a sufficiently low net acceptor concentration of 245 ± 2 meV. These results show that the HVPE method is promising for fabricating GaN vertical power devices, such as n-channel metal–oxide–semiconductor field-effect transistors.
High-temperature vibrational relaxation and decomposition of shock-heated nitric oxide: II. Nitrogen dilution from 1900 to 8200 K
Authors: Streicher Jesse W. , Krish Ajay , Hanson Ronald K.
Published: October 2022

This work investigates the high-temperature vibrational relaxation and decomposition of nitric oxide (NO) diluted in nitrogen (N2) to target the NO–N2 rates relevant to high-temperature air, thereby building off the argon (Ar) experiments investigated in Part I. [J. W. Streicher et al., “High-temperature vibrational relaxation and decomposition of shock-heated nitric oxide. I. Argon dilution from 2200 to 8700 K,” Phys. Fluids 34, 116122 (2022)] Again, two continuous-wave ultraviolet laser diagnostics were used to obtain quantum-state-specific time histories of NO in high-temperature shock-tube experiments, including absorbance (α) in the ground vibrational state of NO, translational/rotational temperature (Ttr), and number density of NO (nNO). The experiments probed mixtures of 2% and 0.4% NO diluted in either pure N2 (NO/N2) or an equal parts N2/Ar mixture (NO/N2/Ar). The NO/N2 experiments spanned initial post-reflected-shock conditions from 1900–7000 K and 0.05–1.14 atm, while the NO/N2/Ar experiments spanned from 1900–8200 K and 0.11–1.52 atm. This work leveraged two vibrational relaxation times from Part I (τVTNO−Ar and τVTNO−NO) and extended measurements to include the vibrational–translational and vibrational–vibrational relaxation times with N2 (τVTNO−N2 and τVVNO−N2). Similarly, this work leveraged the four rate coefficients from Part I (kdNO−Ar, kdNO−NO, kfN2O, and kzNO−O) and extended measurements to include NO dissociation with N2 (kdNO−N2). A few studies have directly inferred these rates from experiments, and the current data differ from common model values. In particular, τVTNO−N2 differs slightly from the Millikan and White correlation, τVVNO−N2 is four times slower than Taylor et al.'s inference, and kdNO−N2 is four times slower than the Park two-temperature model. The unique experimental measurements and dilution in N2 in this study significantly improve the understanding of the vibrational relaxation and decomposition of NO in high-temperature air.
Kinetic coefficient for ice–water interface from simulated non-equilibrium relaxation at coexistence
Authors: Addula Ravi Kumar Reddy , Peters Baron
Published: October 2022

In the theory of solidification, the kinetic coefficient multiplies the local supercooling to give the solid–liquid interface velocity. The same coefficient should drive interface migration at the coexistence temperature in proportion to a curvature force. This work computes the ice–water kinetic coefficient from molecular simulations starting from a sinusoidal ice–water interface at the coexistence temperature. We apply this method to the basal and prismatic ice planes and compare results to previous estimates from equilibrium correlation functions and simulations at controlled supercooling.
Improved torque estimator for condensed-phase quasicentroid molecular dynamics
Authors: Trenins George , Haggard Christopher , Althorpe Stuart C.
Published: October 2022

We describe improvements to the quasicentroid molecular dynamics (QCMD) path-integral method, which was developed recently for computing the infrared spectra of condensed-phase systems. The main development is an improved estimator for the intermolecular torque on the quasicentroid. When applied to qTIP4P/F liquid water and ice, the new estimator is found to remove an artificial 25 cm−1 red shift from the libration bands, to increase slightly the intensity of the OH stretch band in the liquid, and to reduce small errors noted previously in the QCMD radial distribution functions. We also modify the mass-scaling used in the adiabatic QCMD algorithm, which allows the molecular dynamics timestep to be quadrupled, thus reducing the expense of a QCMD calculation to twice that of Cartesian centroid molecular dynamics for qTIP4P/F liquid water at 300 K, and eight times for ice at 150 K.
Fortifying the financial and environmental capital banks in commercially grazed rangelands
Authors: Walsh D. , Holmes P. R.
Published: October 2022

Commercial rangeland livestock producers manage a perpetual conflict. They must ensure that the financial and environmental elements of rangeland grazing remain concurrently robust, with neither borrowing excessively from the other. Successfully managing this financial and environmental tension requires sound financial literacy as it applies to pastoralism, an above-average knowledge of rangeland ecology, and intellectual and practical management skills. Achieving these competencies is the starting point for a truly sustainable rangeland grazing business. The degree to which these competencies are achieved is largely under the control of the people who manage the business. However, there are significant external influences that can impede progress towards better financial and environmental outcomes. In this paper, we draw upon more than 50 years of combined professional experience to present our definitions for financial and environmental sustainability, as they pertain to northern Australian grazing enterprises. We summarise what is currently known about the financial and environmental performance of the northern Australian beef industry, and highlight some of the current external factors that are potentially antagonistic to achieving sustainable livestock production. We conclude with a protocol that our most successful clients have used to achieve (and demonstrate) financial and environmental sustainability.
5-methylcytosine (m
5
C) RNA modification controls the innate immune response to virus infection by regulating type I interferons
Authors: Zhang Yuexiu , Zhang Li-Sheng , Dai Qing , Chen Phylip , Lu Mijia , Kairis Elizabeth L. , Murugaiah Valarmathy , Xu Jiayu , Shukla Rajni Kant , Liang Xueya , Zou Zhongyu , Cormet-Boyaka Estelle , Qiu Jianming , Peeples Mark E. , Sharma Amit , He Chuan , Li Jianrong
Published: October 2022

5-methylcytosine (m
5
C) is one of the most prevalent modifications of RNA, playing important roles in RNA metabolism, nuclear export, and translation. However, the potential role of RNA m
5
C methylation in innate immunity remains elusive. Here, we show that depletion of NSUN2, an m
5
C methyltransferase, significantly inhibits the replication and gene expression of a wide range of RNA and DNA viruses. Notably, we found that this antiviral effect is largely driven by an enhanced type I interferon (IFN) response. The antiviral signaling pathway is dependent on the cytosolic RNA sensor RIG-I but not MDA5. Transcriptome-wide mapping of m
5
C following NSUN2 depletion in human A549 cells revealed a marked reduction in the m
5
C methylation of several abundant noncoding RNAs (ncRNAs). However, m
5
C methylation of viral RNA was not noticeably altered by NSUN2 depletion. In NSUN2-depleted cells, the host RNA polymerase (Pol) III transcribed ncRNAs, in particular RPPH1 and 7SL RNAs, were substantially up-regulated, leading to an increase of unshielded 7SL RNA in cytoplasm, which served as a direct ligand for the RIG-I–mediated IFN response. In NSUN2-depleted cells, inhibition of Pol III transcription or silencing of RPPH1 and 7SL RNA dampened IFN signaling, partially rescuing viral replication and gene expression. Finally, depletion of NSUN2 in an ex vivo human lung model and a mouse model inhibits viral replication and reduces pathogenesis, which is accompanied by enhanced type I IFN responses. Collectively, our data demonstrate that RNA m
5
C methylation controls antiviral innate immunity through modulating the m
5
C methylome of ncRNAs and their expression.
Putting it into context
Authors: Mister Bianca , Chen Honglin , Baker Amanda
Published: October 2022

Developing L2 learners’ productive mastery of vocabulary is a challenging task. Recent research has called for greater attention to understanding how receptive vocabulary may be transformed for productive use (Schmitt, 2019). Using a design-based research methodology, this study investigated adult ESL learners’ productive oral vocabulary development through engaging them in a series of classroom workshops where they were exposed to nine target words in five different contexts. Findings suggest that such exposure to words combined with phonological form-focused elaboration facilitates the development of metalinguistic awareness, specifically the associations between grammatical patterns and word meaning, leading to subsequent productive use of target words. The paper contributes to the understanding that vocabulary training combining a focus on meaning with a focus on phonological and grammatical form may enhance form-meaning mapping, leading to productive oral vocabulary development.
Elucidation of electric characteristics for P and N type polycrystalline silicon vertical thin film transistors
Authors: Zhang Peng , Jacques Emmanuel , Rogel Régis , Pichon Laurent , Bonnaud Olivier
Published: October 2022

P and N type polycrystalline silicon has been applied in thin film transistors (TFTs) for driving a range of displays, and for building up complementary metal oxide semiconductor (CMOS)-like circuits. In one aspect, the high driving current is required, which is usually achieved by improving field effect mobility of the active layer. For another, balanced electrical characteristics are required for achieving CMOS-like logic circuits. In this article, in order to increase driving current, P and N type polycrystalline silicon vertical TFTs configuration is proposed that can get rid of the strict requirement of the field effect mobility in order to increase the driving current. In addition, the balanced electrical properties are demonstrated for P and N type vertical TFTs, which are elucidated by the density of states calculations. The simple Simulation Program with Integrated Circuit Emphasis (SPICE) modelling indicates the potential application in CMOS inverter based on our vertical TFTs.
α-graphyne as a promising anode material for Na-ion batteries: a first-principles study
Authors: Singh Tavinder , Choudhuri Jyoti Roy , Rana Malay Kumar
Published: October 2022

Lithium-ion batteries (LIBs) have emerged as a technological game-changer. Due to the rising price of lithium and the environmental concerns LIBs pose, their use is no longer viable. Sodium (Na) may be the best contender among the alternatives for replacing lithium. Conventional graphite has a limited capacity for Na storage. Hence, α-graphyne, an allotrope of carbon, was studied here as a potential anode material for Na-ion batteries (NIBs), employing density functional theory. In-plane Na atom adsorption results in a semi-metallic to metallic transition of α-graphyne. Electronic transport calculations show an increase in current after Na adsorption in graphyne. The successive adsorption of Na atoms on the surface of graphyne leads to a theoretical capacity of 1395.89 mA h g−1, which is much greater than graphite. The average open circuit voltage is 0.81 V, which is an ideal operating voltage for NIBs. Intra- and inter-hexagon Na diffusions have very low energy barriers of 0.18 eV and 0.96 eV, respectively, which ensure smooth operation during charge/discharge cycles. According to this study, the α-graphyne monolayer thus has the potential to be employed as an anode in NIBs.
Plasma thermal-chemical instability of low-temperature dimethyl ether oxidation in a nanosecond-pulsed dielectric barrier discharge
Authors: Zhong Hongtao , Yang Xin , Mao Xingqian , Shneider Mikhail N , Adamovich Igor V , Ju Yiguang
Published: October 2022

Plasma stability in reactive mixtures is critical for various applications from plasma-assisted combustion to gas conversion. To generate stable and uniform plasmas and control the transition towards filamentation, the underlying physics and chemistry need a further look. This work investigates the plasma thermal-chemical instability triggered by dimethyl-ether (DME) low-temperature oxidation in a repetitive nanosecond pulsed dielectric barrier discharge. First, a plasma-combustion kinetic mechanism of DME/air is developed and validated using temperature and ignition delay time measurements in quasi-uniform plasmas. Then the multi-stage dynamics of thermal-chemical instability is experimentally explored: the DME/air discharge was initially uniform, then contracted to filaments, and finally became uniform again before ignition. By performing chemistry modeling and analyzing the local thermal balance, it is found that such nonlinear development of the thermal-chemical instability is controlled by the competition between plasma-enhanced low-temperature heat release and the increasing thermal diffusion at higher temperature. Further thermal-chemical mode analysis identifies the chemical origin of this instability as DME low-temperature chemistry. This work connects experiment measurements with theoretical analysis of plasma thermal-chemical instability and sheds light on future chemical control of the plasma uniformity.
Electrical transport properties in Ge hyperdoped with Te
Authors: Caudevilla D , Algaidy S , Pérez-Zenteno F , Duarte-Cano S , García-Hernansanz R , Olea J , San Andrés E , del Prado A , Barrio R , Torres I , García-Hemme E , Pastor D
Published: October 2022

In this work we have successfully hyperdoped germanium with tellurium with a concentration peak of 1021 cm−3. The resulting hyperdoped layers show good crystallinity and sub-bandgap absorption at room temperature which makes the material a good candidate for a new era of complementary metal-oxide-semiconductor-compatible short-wavelength-infrared photodetectors. We obtained absorption coefficients α higher than

4.1
×

10

3

cm−1 at least up to 3 µm. In this study we report the temperature-dependency electrical properties of the hyperdoped layer measured in van der Pauw configuration. The electrical behaviour of this hyperdoped material can be explained with an electrical bilayer coupling/decoupling model and the values for the isolated hyperdoped layer are a resistivity of

4.25
×

10

−
3

Ω
⋅

cm with an electron-mobility around −100 cm2 V−1 s−1.
Near-infrared broadband polarization beam splitter with an Au nanocube array
Authors: Zhou Yangyang , Zhou Xingping , Zhuang Rui , Liu Aiping , Wang Qin
Published: October 2022

A near-infrared broadband polarization beam splitter (PBS) is proposed and numerically simulated, which is realized by a directional coupler assisted with an Au nanocube array. The fundamental transverse electric (TE) mode can be coupled to the output of the upper waveguide by exciting the surface plasmon polaritons (SPPs), while the fundamental transverse magnetic (TM) mode is output directly from the lower waveguide. The length of the coupling region of the PBS is only 1 μm. It has a working bandwidth of 210 nm in the range of 1420 ∼ 1630 nm, covering three bands: S-, C- and L-bands. The simulation shows that the extinction ratio of TE and TM polarization is 20.31 dB and 14.15 dB, respectively.
Study of the backscattering of electron beams with energies typical of radiotherapy
Authors: Koohi Behzad , Khabaz Rahim
Published: October 2022

During radiotherapy, the dose of electrons backscattered into the tissue should be taken into account. According to the available data on the electron backscattering phenomenon, the backscatter rate varies depending on the specific radiotherapy delivery configuration. Using the Monte Carlo code MCNPX, the backscattering distribution and their saturation values for electron beams with energies between 4 MeV and 25 MeV (the energies used in electron therapy) of various materials such as polystyrene, aluminum, copper and lead were obtained. Data obtained with MCNPX show that the probability of electron backscattering is strongly dependent on the effective atomic number and the energy of the electron. For low energy electrons, the backscattering probability depends less on the energy and is mainly a function of the effective atomic number of the backscatter material. The saturation values of the backscattering are distributed as a linear function of the effective atomic number of the scattering material for all investigated energies. Therefore, it is recommended that equipment and accessories used with patients in electron radiotherapy LINAC be materials with low atomic numbers (Z), and that a layer of low Z material be used over a higher Z material for protection.
The energy budget of cosmological first-order phase transitions beyond the bag equation of state
Authors: Wang Shao-Jiang , Yuwen Zi-Yan
Published: October 2022

The stochastic gravitational-wave backgrounds (SGWBs) from the cosmological first-order phase transitions (FOPTs) serve as a promising probe for the new physics beyond the standard model of particle physics. When most of the bubble walls collide with each other long after they had reached the terminal wall velocity, the dominated contribution to the SGWBs comes from the sound waves characterized by the efficiency factor of inserting the released vacuum energy into the bulk fluid motions. However, the previous works of estimating this efficiency factor have only considered the simplified case of the constant sound velocities in both symmetric and broken phases, either for the bag model with equal sound velocities orν-model with different sound velocities in the symmetric and broken phases, which is unrealistic from a viewpoint of particle physics. In this paper, we propose to solve the fluid EoM with an iteration method when taking into account the sound-velocity variation across the bubble wall for a general and realistic equation of state (EoS) beyond the simple bag model andν-model. We have found a suppression effect for the efficiency factor of bulk fluid motions, though such a suppression effect could be negligible for the strong FOPT, in which case the previous estimation from a bag EoS on the efficiency factor of bulk fluid motions still works as a good approximation.
Global 21-cm brightness temperature in viscous dark energy models
Authors: Halder Ashadul , Pandey Shashank Shekhar , Majumdar A.S.
Published: October 2022

We investigate the global 21-cm brightness temperature in the context of viscous dark energy (VDE) models. The bulk viscosity of dark energy perturbs the Hubble evolution of the Universe which could cool baryons faster, and hence, alter the 21-cm brightness temperature. An additional amount of entropy is also produced as an outcome of the viscous flow. We study the combined contribution of Hawking radiation from primordial black holes, decay and annihilation of particle dark matter and baryon-dark matter scattering in the backdrop of VDE models towards modification of the 21-cm temperature. We obtain bounds on the VDE model parameters which can account for the observational excess of the EDGES experiment (-500+200-500mK at redshift 14 <z< 20) due to the interplay of the above effects. Moreover, our analysis yields modified constraints on the dark matter mass and scattering cross-section compared to the case of the ΛCDM model.
Far-field scattering control of wave based on all-dielectric blazed encoding metagrating
Authors: He Xuejun , Lin Feng , Huang Wenkang , Li Chenxia , Jing Xufeng
Published: October 2022

Coding metagrating metasurfaces can realize flexible and effective control of polarization, amplitude, and phase of electromagnetic waves. The coded metagrating builds a bridge between the physical unit structure and the digital coding, and can realize the digital coding calculation processing of the physical device. We propose several all dielectric encoded metagrating sequences, and the detailed analysis of their far-field scattering properties is given. Based on the principle of digital coding addition, we add two coding metagrating sequences to obtain a new coding sequence. This new coding sequence results in an additive integration of the functions of the original two coding sequences. This method provides an idea for the realization of multifunctional devices.
3
S
1–3
D
1 coupled channel Λ
c

N interactions: chiral effective field theory versus lattice QCD
Authors: Song Jing , Xiao Yang , Liu Zhi-Wei , Li Kai-Wen , Geng Li-Sheng
Published: October 2022

We study the lattice QCD Λ
c

N phase shifts for the 3
S
1–3
D
1 coupled channel using both the leading order covariant chiral effective theory and the next-to-leading order non-relativistic chiral effective field theory (ChEFT). We show that although it is possible to describe simultaneously the 3
S
1 and 3
D
1 phase shifts and the inelasticity η
1, the fitted energy range is quite small, only up to E
c.m. = 5 MeV. This raises concerns regarding the consistency between leading/next-to-leading order ChEFT and the lattice QCD simulations.
Cyclic controlled remote state preparation in the three-dimensional system
Authors: Ma Peng-Cheng , Chen Gui-Bin , Li Xiao-Wei , Zhan You-Bang
Published: October 2022

In this work, we propose a novel protocol for cyclic controlled remote state preparation (CCRSP) with single-qutrit equatorial states. In this protocol, three distant parties, Alleyn, Breden and Carden, are not only senders but also receivers. Alleyn wants to remotely prepare a single-qutrit equatorial state at Breden’s site, while at the same time, Breden (Carden) wishes to help Carden (Alleyn) remotely preparing another single-qutrit equatorial state. It is shown that, only if the three senders and the controller collaborate with each other, the CCRSP can be completed. To present this protocol more clearly, only maximally entangled channel is considered.
Charge-mediated voltage modulation of magnetism in Hf0.5Zr0.5O2/Co multiferroic heterojunction
Authors: Chen Jia , Yu Peiyue , Zhao Lei , Li Yanru , Yang Meiyin , Xu Jing , Gao Jianfeng , Liu Weibing , Li Junfeng , Wang Wenwu , Kang Jin , Bu Weihai , Zheng Kai , Yang Bingjun , Yue Lei , Zuo Chao , Cui Yan , Luo Jun
Published: October 2022

We construct the Hall-bar device with the size of several hundred nanometers based on the HZO/Co multiferroic heterojunction. A remarkable voltage-controlled magnetism is observed in the device that possesses both ferroelectric property and perpendicular magnetic anisotropy (PMA). The nucleation field and coercivity can be modulated by voltage pulse while saturation field keeps stable. The non-volatile and reversible voltage-controlled magnetism is ascribable to interfacial charges caused by ferroelectric polarization. Meanwhile, the effective anisotropy energy density (K
u) can also be controlled by voltage pulse, a decrease of 83% and increase of 28% in K
u are realized under –3-V and 3-V pulses, respectively. Because the energy barrier is directly proportional to K
u under a given volume, a decreased or enhanced energy barrier can be controlled by voltage pulse. Thus, it is an effective method to realize low-power and high-stability magneto-resistive random-access memory (MRAM).
Finger movement and coactivation predicted from intracranial brain activity using extended block-term tensor regression
Authors: Faes A , Hulle M M Van
Published: October 2022

Objective. We introduce extended Block-Term Tensor Regression (eBTTR), a novel regression method designed to account for the multilinear nature of human intracranial finger movement recordings. Approach. The proposed method relies on recursive Tucker decomposition combined with automatic component extraction. Main results. eBTTR outperforms state-of-the-art regression approaches, including multilinear and deep learning ones, in accurately predicting finger trajectories as well as unintentional finger coactivations. Significance. eBTTR rivals state-of-the-art approaches while being less computationally expensive which is an advantage when intracranial electrodes are implanted acutely, as part of the patient’s presurgical workup, limiting time for decoder development and testing.
Micro solder bump detection of flip chip using improved decision tree model based on SAM image
Authors: Zhou J. , Yang W. , Chen T. , Lu X. , He Z.
Published: October 2022

The increasing packaging density of flip chips brings great
challenges for micro defect detection. It is necessary to develop an
efficient and automatic inspection system for electronic industrial
application. In this paper, the scanning acoustic microscopy (SAM)
technology and the optimized classifier were investigated for the
automatic detection of solder joint defects of flip
chips. Ultrasonic images of 1902 solder bumps from 6 chip samples
were obtained using a SAM equipment. The decision tree model was
improved by introducing the granularity decision entropy. The
feature vectors were extracted from the images of solder bumps, and
then used for classification. The results show that the decision
tree model correctly detected 1812 solder bumps with the accuracy of
95.3%. It is verified that the ultrasonic defect detection system
based on the improve decision tree model has high accuracy for micro
defect inspection, which has potential and promising application in
the electronic packaging industry.
Taking stock of and advancing knowledge on interaction archetypes at the nexus between land, biodiversity, food and climate
Authors: Sietz Diana , Neudert Regina
Published: October 2022

Global challenges related to land, biodiversity, food and climate interact in diverse ways depending on local conditions and the broader context in which they are embedded. This diversity challenges learning and integrated decision-making to sustainably transform the nexus, that is to say the interactions between these land-based challenges. Providing aggregated insights, archetype analysis has revealed recurrent patterns within the multitude of interactions, i.e. interaction archetypes that are essential to enhance the understanding of nexus relations. This paper synthesises the state of knowledge on interaction or nexus archetypes related to land, biodiversity, food and climate based on a systematic literature review. It focusses on the coverage of thematic aspects, regional distribution, social dimensions and methodologies. The results show that consideration of comprehensive land–biodiversity–food–climate interactions is rare. Furthermore, there are pronounced regional knowledge gaps, social dimensions are inadequately captured, and methodological shortcomings are evident. To enhance the investigation of interaction archetypes, we have framed a future research agenda providing directions to fully capture interactions across space and time, better use the potential of scenario archetypes and up-scale transformative actions. These advances will constructively contribute insights that help to achieve the ambitious objective to sustainably transform the nexus between land, biodiversity, food and climate.
The SAGEX review on scattering amplitudes Chapter 11: Soft Theorems and Celestial Amplitudes
Authors: McLoughlin Tristan , Puhm Andrea , Raclariu Ana-Maria
Published: October 2022

The soft limits of scattering amplitudes have been extensively studied due to their essential role in the computation of physical observables in collider physics. The universal factorisation that occurs in these kinematic limits has been shown to be related to conservation laws associated with asymptotic, or large, gauge symmetries. This connection has led to a deeper understanding of the symmetries of gauge and gravitational theories and to a reformulation of scattering amplitudes in a basis of boost eigenstates which makes manifest the two-dimensional global conformal symmetry of the celestial sphere. The recast, or celestial, amplitudes possess many of the properties of conformal field theory (CFT) correlation functions which has suggested a path towards a holographic description of asymptotically flat spacetimes. In this review we consider these interconnected developments in our understanding of soft theorems, asymptotic symmetries and CFT with a focus on the structure and symmetries of the celestial amplitudes and their holographic interpretation.
Investigation of Water Hammer Overpressure in the Hydraulic Passages of Hydropower Plants Equipped with Francis Turbines
Authors: Lupa S-I , Gagnon M , Muntean S , Abdul-Nour G
Published: October 2022

Water hammer shortens hydraulic passage lifespan and may cause sudden failure. The primary goal is to use a hierarchical approach to assess the main parameters associated with water hammer. This will help investigate their influence and assist in decision making. Analytical calculation results and a numerical model are compared against experimental data. Our investigations examine water hammer overpressure loading induced by transient regimes. We used data from experimental campaigns carried out within the Hydro-Québec fleet that cover different types of hydraulic turbines and hydraulic passage configurations as experimental dataset. Guide vane closing rate was the main parameter controlled during the overpressure experiments and a general trend was identified for overpressure. This empirical trend is compared to model estimates in order to validate the hypothesis taken into account for calculations. An in-depth understanding of the water hammer phenomenon helps to select the appropriate theoretical model and recommend the optimal operating parameters to extend lifetime and to avoid catastrophic failures. Our study case suggests that available experimental data can be used along with gradually increasing analysis complexity to identify the optimal methodology for a given configuration.
Application of hydro-abrasive erosion model from IEC 62364:2019 standard in Francis turbines
Authors: Acharya N , Gautam S , Chitrakar S , Trivedi C , Dahlhaug O G
Published: October 2022

Hydro-abrasive erosion in hydraulic turbines is critical and one of the prominent issue due to its association with maintenance costs and production losses in the hydropower plant. IEC 62364:2019* standard guide focuses mainly on hydroelectric powerplant equipment and provides the standard on particle abrasion rates on several combinations like operating conditions, component materials properties, water quality among many factors. With the consideration of different critical parameters, a theoretical model of abrasion rate on hydraulic turbines is proposed by IEC 62364:2019. Present study is conducted to elucidate the several terms used in the theoretical model of abrasion rate for Francis turbine as per the guidelines. The work has taken account into run-off river (RoR) hydropower plant consisting of Francis runner operating in sediment laden rivers in the Himalayan area. Theoretical expected erosion depth for runner inlet, runner outlet, guide vanes facing plates and labyrinth seals is calculated. Characteristic velocities of runner (Wrun) and guide vanes (Wgv) were estimated to be 32.26 m/s and 35.05 m/s respectively. Particle load was calculated based upon the sampling data available from the site. Measurement data from field observation during overhauling was used for comparison with the data calculated from empirical relation. For 229 hours operation of turbine, observed abrasion depth varies from 8.1 mm in guide vanes to 1.5 mm in labyrinth ring corresponding to calculated values of 7.53 mm and 1.89 mm for same components. Results shows good correlation among calculated values from IEC and measured values from the site. An optimized solution can thus be devised based on the evaluation of hydro-abrasive erosion along with energy production and maintenance expenses.

*IEC 62364:2019. Hydraulic machines - Guidelines for dealing with hydro-abrasive erosion in Kaplan, Francis, and Pelton turbines. Edition 2.0 (March 2019) International Electrotechnical Commission, Geneva, Switzerland [1]
Automated hydraulic design procedure for a Francis turbine spiral casing
Authors: Lazarevikj M , Markov Z
Published: October 2022

The spiral casing of a Francis turbine distributes the water from the penstock to the stay and guide vanes circumferentially and uniformly, which is important for achieving the required flow conditions at the runner entrance. Moreover, the spiral casing is supposed to provide the required inlet velocity in front of the stay vanes and create minimal hydraulic losses. The dimensions and shape of the spiral casing depend on the hydraulic and energy parameters of the turbine. A calculation methodology for a Francis spiral casing hydraulic design is presented in this paper. The methodology developed is based on the main condition to achieve a uniform water flow rate into the stay vanes system and the wicket gate over the entire perimeter. The free vortex flow theory is implemented in this research, where the design is based on the law of constant velocity moment. The parametric definition of the spiral casing makes the geometries generated for certain input combinations suitable for numerical analysis using commercially available Computational Fluid Dynamics (CFD) software. The calculation procedure can be used for any set of energy and geometry turbine parameters, such as water discharge, angle of streamline departing from the spiral casing, and stay ring diameter and height. The automated approach integrating MATLAB and ANSYS Workbench capabilities is presented as a spiral casing design tool. The product is a design solution proposed on basis of the turbine parameters. The spiral casing geometry generation is followed by a CFD analysis. Considering input parameters of different existing Francis turbines, the spiral casing is redesigned accordingly. One of the obtained spiral casings geometry is numerically tested. The results show that the uniform discharge distribution is achieved. The automation of the design procedure allows further optimization based on chosen input parameters.
Design and development of non-recirculating type erosion test setup for hydraulic turbines
Authors: Kapali A , Neopane H P , Chitrakar S , Shrestha O
Published: October 2022

Slurry erosion phenomena are inevitable and commonly occurring processes in all types of hydro turbines and components that are exposed to sediment particles. The design of these components and the choice of the materials to resist erosion require laboratory testing using various erosion testing apparatus. These test apparatuses are designed specifically to meet the particular study requirements and to simulate the actual flow conditions in turbines. However, the design of these test apparatus must be flexible and versatile to assess erosion resistance under different combinations of operating conditions. The existing test rigs mostly comprise of rotary type with re-circulation of the slurry. This study proposes a new type of test setup that describes the sediment particles injection method into the system as well as immediate rejection of those particles striking the test specimen. The components of test rig and the test methodology are described. An accelerated tests have been performed on Cross-flow turbine to verify the suitability of the rig for erosion testing in laboratory environment. The design principle of this setup is to eliminate the limitations of the existing test rigs such as slurry ageing problem, use of acceleration tube to maintain the particle velocity and constant operating parameters (discharge velocity and pressure head). The non-recirculation of the slurry is maintained by the use of hydro cyclone as the particle separation device, which is found to have an efficiency of 97%. This test facility provides flexibility in the performance testing of miniature model of different types of hydro turbines with limited adjustments.
Development of a Novel Cavitation Monitoring System for Hydro Turbines Based on Machine Learning Algorithms
Authors: Amini Ali , Pacot Olivier , Voide Dominique , Hasmatuchi Vlad , Roduit Pierre , Münch-Alligné Cécile
Published: October 2022

Operating hydro turbines in off-design conditions increases the risk of cavitation occurrence, which in turn, leads to numerous problems such as performance degradations, structural vibrations, and most importantly, mechanical damage due to erosion. It is therefore crucial to develop a monitoring system that detects the occurrence and severity of cavitation in real time. For this purpose, a cavitation detection methodology has been developed that is based on the analysis of acoustic emissions of a turbine with machine learning algorithms. In this method, a conventional microphone is used to record the airborne noise emitted from a turbine under different working conditions, and then, a supervised learning algorithm is trained to classify the recorded noise signals into cavitating and non-cavitating categories. The detection system was developed based on laboratory tests and was validated in Ernen hydropower plant located in Canton of Wallis in southeast of Switzerland. This power plant consists of two identical double-flux Francis turbines each having a maximum power of 16 MW and a net head of 270 mWC. The preliminary results obtained from a two-day experimental campaign in the Ernen powerplant are very promising in terms of cavitation detection with a classification accuracy of more than 90 %. The system could be implemented either for real-time monitoring of cavitation occurrence allowing the operators to avoid such a condition or as a post processing tool to evaluate the number of hours a turbine has worked under severe conditions. Work is still ongoing to deploy more complex learning algorithms for this task to minimize expert intervention and/or interpretation during the setup process.
Evaluation of fish-related properties of Kaplan turbines at the design phase: simulation-based outcomes vs. experimental data
Authors: Romero-Gomez P , Salalila A , Deng D Z , Peyreder R
Published: October 2022

The development of turbine technology faces growing demands to maximize the survival of migratory fish entrained into turbine flows. In this context, two strategies have emerged for quantifying hazardous hydraulic conditions: computer-based evaluations at design stage and recordings with autonomous sensors deployed in prototypes. The former is a desktop evaluation with many modelling assumptions (idealization) and the latter is a field technique that introduces various unknown and uncontrollable factors (uncertainty.) The present work introduces and implements a third method based on test rig measurements and the corresponding computer-based predictions of conditions that negatively affect fish survivability. The experimental work was conducted in a five-bladed Kaplan turbine model in which miniaturized autonomous sensors (SF Mini, developed at the Pacific Northwest National Laboratory, U.S.) measured fish-relevant hydraulic features. The modelling work involved flow simulations according to industry practices and the representation of fish trajectories through the simulated flow conditions. We compared both the experimental measurements and CFD outcomes and discussed the challenges and advantages of the modelling strategies, as well as the benefits for turbine engineers in need of incorporating effective design concepts to mitigate fish mortality through turbines.
Experimental and numerical validation of a Francis turbine draft tube designed for mitigation of pressure fluctuations
Authors: Favrel Arthur , Irie Tatsuya , Ishii Yuya , Lee Nak-joong , Miyagawa Kazuyoshi
Published: October 2022

This paper presents an experimental and numerical investigation of the internal flow in a Francis turbine draft tube previously designed for minimizing pressure fluctuations and energy losses in off-design conditions. The design of the draft tube geometry is based on an original approach combining Design of Experiments and steady/unsteady Computational Fluid Dynamics (CFD) simulations of the draft tube internal flow. The proposed method provides new insight on the influence of the draft tube geometry on the flow dynamic behaviour on one hand and enables the determination of a geometry promoting flow stability and hydraulic performance on another hand. CFD simulations of the internal flow in the final geometry showed promising results in terms of flow stability compared with the initial geometry designed by conventional CFD-aided methods. A reduced-scale model of the prototype machine featuring the final draft tube geometry is finally installed and tested in laboratory. Tests include performance and pressure fluctuations measurements over the complete operating range. The analysis of the results shows that the draft tube flow remains globally stable over the complete part-load range with pressure fluctuations amplitude lower than 1% of the net head. It is also shown that the dominant pressure component at the runner outlet in the draft tube cone is of synchronous nature. The physical mechanisms of excitation are finally highlighted by analysis of unsteady CFD simulation results.
Hydroacoustic interaction between draft tube and penstock eigenmodes under Francis turbine full load instability
Authors: Alligné S. , Nicolet C. , Vaillant Y. , Lowys P-Y. , Heraud J. , Lecomte B.
Published: October 2022

At high load, Francis Turbines may experience self-sustained pressure surge leading to significant power swing and pressure fluctuations along the waterway. The physical mechanism initiating this instability phenomenon has been the subject of much research. The development of the axisymmetric cavitating vortex rope at the runner outlet modifies the hydroacoustic properties of the draft tube waterway. Very low wave speed due to high cavitation volume combined with a high swirling number initiates the unstable axial pulsations of the cavitating vortex rope which frequency corresponds to a penstock’s eigenfrequency. The 15 MW power plant of Monceaux-la-Virole in France, composed of two units fed by a single penstock, experiences such full-load surge. On-site tests have been carried out to analyze the envelope of pressure fluctuations along the penstock once instability occurs. Combined with a 1D SIMSEN model of the power plant, these measurements have allowed to enhance the understanding of this instability phenomenon. To achieve this, an advanced draft tube modelling taking into account distributed wave speed, convective terms and divergent geometry is used and frequency analysis is carried out. Unstable draft tube eigenmodes and stable penstock eigenmodes are predicted. The key draft tube model parameters such as wave speed and second viscosity are calibrated to set the draft tube eigenmode frequency to the unstable measured frequency for different operating points. This frequency analysis concludes that high load instability occurs when a matching between the draft tube and the penstock eigenfrequencies is experienced. Moreover, it is shown that the unstable draft tube eigenmode is able to interact with different order penstock eigenmodes as function of the operating point of the unit.
Influence of axial water jet size on RVR mitigation in draft tube of Francis turbine
Authors: Khullar S , Kumar S , Singh K M , Cervantes M J , Gandhi B K
Published: October 2022

The present work investigates the effect of the axial water jet nozzle size on the unsteady pressure fluctuations arising from RVR formation in the draft tube of a Francis turbine operating at part load. The results compare two different nozzle diameter jets for their effect on the pressure pulsations and pressure recovery in the draft tube. Simulations were carried out at four jet injections varying from 2% to 10% of the main discharge. The study also presents the changes in the net effective area and average swirl in the draft tube with the introduction of the water jet.