bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel axial dynamic mechanical analysis setup for thermo-analytical study and curing kinetics optimization of thermoset adhesives
Authors: Verker R. , Wallach E. R. , Vidavsky Y. , Bolker A. , Gouzman I.
Published: March 2022

Thermo-analytical studies of thermoset adhesives, either during research and development or in quality assurance activities, involve the application of various analytical equipment for adhesive characterization, from initial mixing to final product decomposition. Gelation is usually measured with rheometers or dynamic mechanical analyzers (DMAs); curing, post-curing, and curing kinetics are often studied using differential scanning calorimetry (DSC). Glass transition temperature (Tg) is measured via DSC or DMA, and finally, thermal decomposition measurements are done using thermal gravimetric analysis. Here, we present a new curing kinetics optimization module (C-KOM), an extension to an axial DMA, and a protocol for its usage, which combines elements from all of the above thermo-analytical techniques into one tool. As a case study, we apply C-KOM to investigate the effect of the curing temperature on the physical properties of an epoxy adhesive including gelation and end of cure points as well as its Tg. The data collected via C-KOM were used to extract the adhesive’s curing reaction rates and its activation energy. Our research allowed us to compare and evaluate previously suggested curing procedures and assess their validity. As a final step, the thermal decomposition temperature of the epoxy adhesive was also identified via C-KOM. The newly suggested C-KOM setup provides a fast path toward characterization and optimization of the curing processes of thermoset materials in a way that was not available before.
Quantum nickelate platform for future multidisciplinary research
Authors: Zhang Zhen , Sun Yifei , Zhang Hai-Tian
Published: March 2022

Perovskite nickelates belong to a family of strongly correlated materials, which have drawn broad attention due to their thermally induced metal-to-insulator transition. Recent discoveries show that orbital filling mediated by ion intercalation can trigger a colossal non-volatile conductivity change in nickelates. The coupling and interaction between two types of charge carriers (i.e., ions and electrons) enable nickelate as an exotic mixed conductor for electronic, biological, and energy applications. In this Perspective, we first summarize the fundamentals and recent progresses in the manipulation of ground states of perovskite nickelates by controlling orbital filling via ion intercalation. Then, we present a comprehensive overview of perovskite nickelate as a unique platform for vast cutting-edge research fields, including neuromorphic computing, bio-electronic interfaces, as well as electrocatalysis applications by taking advantage of such electron-filling-controlled modulation phenomena. Finally, we provide an overview of future perspectives and remaining challenges toward the exploitation and commercialization of quantum nickelates for future multidisciplinary research.
Formation of the spatial structure of pump radiation in the focal plane of a lens for different types of stimulated light scattering
Authors: Gordeev A.A. , Efimkov V.F. , Zubarev I.G.
Published: March 2022

Experiments of our earlier work on the study of stimulated thermal scattering of the second harmonic of neodymium laser radiation in toluene are reproduced in order to confirm the put forward hypothesis about the nature of the laser beam structure decay in the focal plane of a short-focus lens. Experiments were carried out under similar conditions, but with a liquid (CCl4), in which there is no two-photon absorption of the second harmonic radiation from a neodymium laser. A conclusion is made that the spatial structure decay of the laser beam of the second harmonic of the Nd : YAG laser radiation focused by short-focus lenses with a numerical aperture NA ∼ 0.1 in toluene is associated with two-photon absorption.
Broadband emission from polycrystalline graphite
Authors: Rekhviashvili S.Sh. , Gaev D.S. , Margushev Z.Ch.
Published: March 2022

Visible radiation spectra of polycrystalline graphite under electrical and laser excitation is studied. It is shown that two different mechanisms of photon emission with a broadband spectrum are implemented in this material. The radiation arising as a result of resistive heating is thermal radiation, whose parameters are close to those of blackbody radiation. The laser-induced secondary radiation in the visible range is anti-Stokes luminescence. A red shift of the laser-induced radiation from fine-grained graphite with respect to the similar spectrum of a bulk sample is observed.
Application of PT-symmetry properties to increase the limiting sensitivity of resonator optical gyroscopes
Authors: Shalymov E.V. , Akhmadiev T.M. , Davydov V.B.
Published: March 2022

We propose and describe the use of a system with PT-symmetry properties in resonator optical gyroscopes. It is shown that this makes it possible to increase the limiting sensitivity and does not introduce disadvantages typical of PT-symmetric laser gyroscopes. In the example considered in the paper, the inclusion of a system with PT-symmetry properties in the composition of a resonator optical gyroscope allows one to increase the limiting sensitivity by a factor of 750.
The Autler – Townes effect, the Rabi frequency, and determination of characteristics of the decay of excited states in the photoionisation scheme of lutetium
Authors: D’yachkov A.B. , Gorkunov A.A. , Labozin A.V. , Mironov S.M. , Firsov V.A. , Tsvetkov G.O. , Panchenko V.Ya.
Published: March 2022

The splitting of the first and second transitions in the lutetium photoionisation scheme

is studied in a wide range of laser radiation intensities, and the Rabi frequencies as functions of the radiation intensity are determined. Based on the results, we have obtained the decay branching coefficients of 0.54 and 0.41 for the first and second transitions, respectively.
Carbon sources and pathways for citrate secreted by human prostate cancer cells determined by NMR tracing and metabolic modeling
Authors: van Heijster Frits H. A. , Breukels Vincent , Jansen Kees (C.) F. J. , Schalken Jack A. , Heerschap Arend
Published: March 2022

Significance

The human prostate accumulates high luminal citrate levels to serve sperm viability. There is only indirect qualitative evidence about metabolic pathways and carbon sources maintaining these levels. Human citrate-secreting prostate cancer cells were supplied with
13
C-labeled substrates, and NMR spectra of extracellular fluid were recorded. We report absolute citrate production rates of prostate cells and direct evidence that glucose is the main carbon source for secreted citrate. Pyruvate carboxylase provides sufficient anaplerotic carbons to support citrate secretion. Glutamine carbons exchange with carbons for secreted citrate but are likely not involved in its net synthesis. Moreover, we developed metabolic models employing the
13
C distribution in extracellular citrate as input to assess intracellular pathways followed by carbons toward citrate.
CSF-1 maintains pathogenic but not homeostatic myeloid cells in the central nervous system during autoimmune neuroinflammation
Authors: Hwang Daniel , Seyedsadr Maryam S. , Ishikawa Larissa Lumi Watanabe , Boehm Alexandra , Sahin Ziver , Casella Giacomo , Jang Soohwa , Gonzalez Michael V. , Garifallou James P. , Hakonarson Hakon , Zhang Weifeng , Xiao Dan , Rostami Abdolmohamad , Zhang Guang-Xian , Ciric Bogoljub
Published: March 2022

Significance

Multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), are autoimmune diseases characterized by accumulation of myeloid cells in the central nervous system (CNS). Both harmful and beneficial myeloid cells are present in EAE/MS, and a goal of MS therapy is to preferentially remove harmful myeloid cells. The receptor for CSF-1 (CSF-1R) is found on myeloid cells and is important for their survival. CSF-1R can bind two ligands, CSF-1 and IL-34, but it is not known whether their functions in EAE/MS differ. We found that blocking CSF-1 depleted only harmful myeloid cells in the CNS and suppressed EAE, whereas blocking IL-34 had no effect. Thus, we propose that blocking CSF-1 could be a therapy for MS.
Bioinspired drag reduction surfaces via triple lithography method based on three-layer hybrid masks
Authors: Zhou Zidan , Yan Zexiang , Zhang Kun , Zhou Wenyuan , Ou Zhaoyang , Lv Xianglian , He Yang , Yuan Weizheng
Published: March 2022

Drag reduction is a significant challenge for many industries, such as ships, pipelines, aircraft, energy, and transportation. Multilayer hierarchical microstructures can inhibit the development of vortices near the wall, which is beneficial to drag reduction. However, existing methods have difficulty performing the controlled fabrication of complex multilayer hierarchical microstructure arrays. Here, a novel triple lithography method based on three-layer hybrid masks is proposed for the controlled fabrication of three-dimensional multilayer hierarchical microstructure surfaces. The capability of the proposed process is verified by the multilayer hierarchical microstructures. In the fabrication process, a special lithography sequence is designed based on the hybrid mask materials. The drag reduction ability of the multilayer hierarchical microstructures is investigated in a closed air channel measurement system. The experimental results demonstrate that the fabricated multilayer hierarchical microstructures exhibit significant drag reduction ability under certain conditions. Conceptual models based on the fluid-solid coupling interface interaction are proposed to explain the drag reduction mechanism of multilayer hierarchical microstructures. The proposed fabrication method provides a powerful means for practical engineering applications of various bioinspired functional surfaces, such as drag reduction, anti-icing, antifouling, self-cleaning, and superhydrophobic surfaces.
Etch the borosilicate glass to form a straight through-glass-via based on the FLACE technology
Authors: Xu Qianfeng , Fang Dan , Zhang Xiaodong , Chen Yu , Wang Xiaohua , Cai Yong , Zhang Baoshun , Wei Zhipeng
Published: March 2022

Interposers will become in demand for advanced electronic systems and through the substrate, vias are essential for 3D integration. A straight via is necessary because a tapered hole is accompanied by large signal loss. This article reports a straight through-glass-via (TGV) fabricated by femtosecond laser-assisted chemical etching (FLACE). The femtosecond laser was used to modify the glass substrates, and the modified glass samples were etched with hydrofluoric acid (HF) solution to form TGV. The effects of key processing parameters, including laser pulse energy, the number of burst pulses, and the HF solution concentration, on the TGV taper profile, were systematically investigated. It was found that The TGV taper sidewall angle decreases with increasing laser pulse energy and increases with increasing HF solution concentration. The number of bursts should be optimized because more than 10 bursts would prevent TGV formation. The study shows via etched in 3 wt% HF after irradiation with 3 bursts of 60 μJ can become approximately vertical. Among the three processing parameters, HF concentration was found to be the most crucial parameter. This work can serve as a critical reference for applications of TGV in high-performance 3D integrated circuits.
A novel pattern reconfigurable dual beam Vivaldi antenna with water-based absorbers
Authors: Cheng Houyuan , Yang Helin , Wu Jiong , Li Yujun , Hua Lina , Yang Yuejie
Published: March 2022

In this paper, a novel orthogonal dual-beam Vivaldi antenna loaded with metamaterial lenses (MLs) is designed as the original antenna. Then, we designed two simple water-based absorbers (WBAs) containers using 3D printing technology, which can be mounted on the ML. WBA filled with water can absorb electromagnetic waves radiated from antenna aperture, while empty WBA does not affect antenna radiation. The antenna radiation pattern can be reconstructed by selectively injecting water into WBAs. The proposed antenna can realize three radiation states in the operating frequency band, including radiation along the X direction and Y direction at the same time (state 1), radiation along X direction (state 2), and radiation along the Y direction (state 3). The proposed antenna has an operating frequency range from 3 GHz to 6 GHz, which realizes the coverage of the 5G sub-6 GHz main frequency band. Finally, the measured results of the antenna are consistent with the simulated. The work in this paper has potential application value in the 5G communication system and point-to-point communication system.
Pressure-induced transitions in RCo5 (R
= Y, La) studied by x-ray emission spectroscopy, x-ray diffraction and density functional theory
Authors: Yamaoka Hitoshi , Schwier Eike F , Yamamoto Yoshiya , Kawai Takuma , Tsujii Naohito , Hirao Naohisa , Hiraoka Nozomu , Ishii Hirofumi , Mizuki Jun’ichiro
Published: March 2022

The hydrostatic pressure dependent evolution of the electronic and magnetic structure of LaCo5 and YCo5 was investigated by means of x-ray emission spectroscopy, x-ray diffraction, and spin-polarized density functional theory (DFT) calculations. Using experimental lattice parameters the DFT correctly predicts the pressure of the magnetic transition in both compounds to be 26 GPa (La) and 22–23 GPa (Y). The transition was experimentally resolved in the changes of the electronic structure via the integrated absolute difference of the Co Kβ emission spectra. Comparison of theory and experiment confirm for the first time a common feature in both LaCo5 and YCo5 to be the source of the transition; the Fermi-level crossing of an up-spin polarized flat band driving the systems into a low spin configuration via a Lifshitz type transition of the Fermi surface. Another phase transition observed around 12 GPa in LaCo5 was clarified to be caused by the change in the down-spin density of states at the Fermi level.
Estimation of metal state in molten production processes using electromagnetic tomography with fast integrated processing
Authors: Chen Ziqi , Hao Haibin , Salas-Avila J R , Fan Mingyang , Xie Yuedong , Wang Shupei , Li Jiyao , Xu Jianxin , Wang Hua , Yin Wuliang
Published: March 2022

This paper presents imaging of copper slag solidification processes using electromagnetic tomography (EMT). It describes key components of the measurement system including a sensor that can operate in the harsh temperature environments. An integrated process tomography system is detailed that includes the main processing unit, i.e. a field programmable gate array and other front end circuitries. It is capable of delivering a wide excitation signal frequency ranging from 0.1 Hz to 500 kHz and a fast speed of 131 frames s−1 with a typical signal-to-noise ratio of 66 dB–95 dB. Measurement trials were conducted on a molten converter slag solidification process where the copper slag changes from the molten state to solidification state during the cool-down for more than an hour. The phenomenon in which the disorderly distributed metal gradually forms solid and permeable object was observed, which can indicate the status of the process. This is the first report of observing such a process using an EMT system. Moreover location-based convergence analysis has been carried out in the imaging space and useful new insights have been gained for the copper production process, which would be difficult to obtain otherwise. Verification and calibration using x-ray diffraction and scanning electron microscope indicate the viability of the EMT-based measurement method.
Billiard ball vs rubber ball collisions
Authors: Cross Rod
Published: March 2022

When two billiard balls collide head-on on a smooth, horizontal surface, momentum and kinetic energy are both conserved to a good approximation. If the experiment is repeated with two rubber balls, then kinetic energy is not conserved and neither is momentum. The latter result can be explained in terms of the external friction forces involved.
Gliding for Olympic success
Authors: Heck André , Uylings Peter
Published: March 2022

When thinking about Olympic winter sports and watching events on television, people mostly focus on events where the chances of success are high for fellow-countrymen. For example, in the Netherlands speed skating is considered the main winter sports event. But with Kimberley Bos there is now also a Dutch medal candidate for the Winter Olympics 2022 in the skeleton discipline. Where speed skaters prepare in summer for the winter season with roller skates, Bos trains on an athletics track with a self-built board on wheels as a replacement for the skeleton. British athletes on the other hand can choose the bobsleigh and skeleton push-start track at the University of Bath for their summer preparation. We prepare for the upcoming Winter Olympics 2022 by taking a physics view on advanced sleighing. We show how school physics helps understanding the motion of athletes in bobsleigh and skeleton and increases respect for the athletes’ performance.
Feasibility study of a proton CT system based on 4D-tracking and residual energy determination via time-of-flight
Authors: Ulrich-Pur Felix , Bergauer Thomas , Burker Alexander , Hirtl Albert , Irmler Christian , Kaser Stefanie , Pitters Florian , Rit Simon
Published: March 2022

Objective. For dose calculations in ion beam therapy, it is vital to accurately determine the relative stopping power (RSP) distribution within the treatment volume. A suitable imaging modality to achieve the required RSP accuracy is proton computed tomography (pCT), which usually uses a tracking system and a separate residual energy (or range) detector to directly measure the RSP distribution. This work investigates the potential of a novel pCT system based on a single detector technology, namely low gain avalanche detectors (LGADs). LGADs are fast 4D-tracking detectors, which can be used to simultaneously measure the particle position and time with precise timing and spatial resolution. In contrast to standard pCT systems, the residual energy is determined via a time-of-flight (TOF) measurement between different 4D-tracking stations. Approach. To show the potential of using 4D-tracking for proton imaging, we studied and optimized the design parameters for a realistic TOF-pCT system using Monte Carlo simulations. We calculated the RSP accuracy and RSP resolution inside the inserts of the CTP404 phantom and compared the results to a simulation of an ideal pCT system. Main results. After introducing a dedicated calibration procedure for the TOF calorimeter, RSP accuracies less than 0.6% could be achieved. We also identified the design parameters with the strongest impact on the RSP resolution and proposed a strategy to further improve the image quality. Significance. This comprehensive study of the most important design aspects for a novel TOF-pCT system could help guide future hardware developments and, once implemented, improve the quality of treatment planning in ion beam therapy.
A multi-posture 3D printed actuator composed of VT-type bidirectional deflection fishbone-like modules based on shape memory alloy wires
Authors: Li Xiaozheng , Liu Shutian , Tong Liyong , Gao Renjing
Published: March 2022

In this paper, a multi-posture actuator (MPA) composed of VT-type bidirectional deflection fishbone-like modules (VBFM) based on shape memory alloy (SMA) wires is proposed for realizing multi-posture deformation control. Through sizing of the VT-type structure and the arrangement of VBFM in series, it is possible to realize the actuator design meeting specific deformation requirements. The thermo-mechanical coupling analysis model based on kinematics, dynamics, thermodynamics and SMA models is established to study the VBFM deflection angle and multi-posture performance of the MPA. The experimental and numerical results show that the MPA can achieve the target postures and the maximum deflection angle of the single VBFM can reach about 1.8°, and the 5-VBFM MPA can deflect a maximum angle of approximately 9° in one direction. In addition, the load actuation performance of 1-VBFM and 5-VBFM MPA is investigated, and the results show that the actuated deflection angle increases with the input electrical power within its effective range and decreases with the external resistance load. When multiple modules are combined, the deflection angle can be accumulated, and they can be used in medical robotic arms, space cleaning grab mechanisms, etc.
Laser osteoperforation of lumbar facet joints: experimental study on mini pigs
Authors: Lychagin A V , Cherepanov V G , Ivannikov S V , Radenska-Lopovok S G , Yang Ya , Startseva E D , Drogin A R , Zharova T A , Vyazankin I A
Published: March 2022

Lumbar pain holds one of the leading positions of prevalence in the world. The common cause of vertebrogenic pain syndrome is spondylarthrosis. Conservative management of spondylarthrosis does not consistently provide an evident therapeutic effect. Open surgical treatment of spondylarthrosis also has a number of disadvantages due to a high risk of postoperative complications and high injury rate. Experimental determination of optimal operational modes of the devices for laser osteoperforation of lumbar facet joints was the purpose of this study. The experiment was performed in March 2020. Within the experiment, laser osteoperforation of lumbar facet joints was performed in experimental animals (mini pigs) with simultaneous measurement of the temperature on the surface and within the tissue and with further histological examination of bone material. The Ethics Committee Approval for the experiment was preliminarily obtained. The highest temperature of 79 °С was registered while performing open laser osteoperforation of the facet joint. Eventually, the following optimal operational modes of laser devices were determined: 2.0 W in continuous mode for radiation with the wavelength of 0.97 µm, and 5.0 W in pulse-periodic mode for radiation with the wavelength of 1.56 µm at the pulse length of 100.0 ms and the pause length of 50.0 ms. Histological examination results were obtained. The optimal modes of laser exposure while performing osteoperforation of facet joints were experimentally worked through and determined, which was further proven by the histological examination data. It makes sense to continue the exploratory development to implement the method in clinical practice.
Real-time assessment of tumor-induced by DMBA in mice model guided by swept-source optical coherence tomography
Authors: Indoliya Abhishek , Pal Kaustav , Pattnaik Ashok Kumar , Poddar Raju
Published: March 2022

To better understand any tumor, first, we need to know the characteristic features. The tumor microenvironment is that the signature helps us know the dermatological condition for biopsy. Some traditional optical imaging methods have restricted properties to visualize shallow skin highlights, and boundary data is missing to identify pathophysiology relationships of skin infections. Here, we illustrate a swept-source optical coherence tomography (SSOCT) technique that non-invasively visualizes (in-vivo) the tissue micro-structure/neoplastic changes during tumor development as optical biopsy in real-time with pathophysiological correlations in the mice model. To further validate the current study, we perform the corresponding histopathology (ex-vivo) of that tumor region. Furthermore, the scattering coefficient and the optical penetration depth analysis prove that SSOCT imaging can provide detailed findings and treatment in dermatology.
Shadows and observation intensity of black holes in the Randall–Sundrum brane world model *
Authors: He Ke-Jian , Zhang Xiao , Li Xin
Published: March 2022

The shadow and observation intensity of a black hole surrounded by a thin spherical accretion in the Randall–Sundrum brane world model are investigated. The bulk metric depends on the tidal charge parameter, q, and deformation parameter, C. It reduces to the metric that possesses similar form with the Reissner–Nordström metric if

. It is shown that the radius of the photon sphere of this black hole depends only on the tidal charge parameter. The radius of the photon sphere decreases with higher q. The observation intensity is mainly influenced by the tidal charge parameter, q, and the deformation parameter, C, is of secondary importance. In the optical observation, the black holes appear brighter with higher q or lower C.
SCC-MPGCN: self-attention coherence clustering based on multi-pooling graph convolutional network for EEG emotion recognition
Authors: Zhao Huijuan , Liu Jingjin , Shen Zhenqian , Yan Jingwen
Published: March 2022

The emotion recognition with electroencephalography (EEG) has been widely studied using the deep learning methods, but the topology of EEG channels is rarely exploited completely. In this paper, we propose a self-attention coherence clustering based on multi-pooling graph convolutional network (SCC-MPGCN) model for EEG emotion recognition. The adjacency matrix is constructed based on phase-locking value to describe the intrinsic relationship between different EEG electrodes as graph signals. The graph Laplacian matrix is obtained from the adjacency matrix and then is fed into the graph convolutional layers to learn the generalized features. Moreover, we propose a novel graph coarsening method called SCC, using the coherence to cluster the nodes. The benefits are that the dimensionality of adjacency matrix can be reduced and the global information can be achieved from the raw data. Meanwhile, a MPGCN block is introduced to learn the generalized features of emotional states. The fully-connected layer and a softmax layer are adopted to derive the final classification results. We carry out the extensive experiments on DEAP dataset and the results show that the proposed method has better classification results than the state-of-the-art methods with the ten-fold cross-validation. And the model achieves the emotion recognition performance with a mean accuracy of 96.37%, 97.02%, 96.72% on valence, arousal, and dominance dimension, respectively.
Phase-field microstructure-based effective thermal conductivity calculations in tungsten
Authors: Li Bingchen , Jin Shuo , Xue Bowen , Liang Linyun , Lu Guang-Hong
Published: March 2022

Using a phase-field approach with the heat conduction equation, we predict the grain growth behaviors in tungsten (W) and their effects on effective thermal conductivity. Results show that the simulated grain growth kinetics is basically consistent with experimental observations. An empirical correlation is derived, describing the averaged grain area as a function of temperature and time. Further, we study the effect of grain growth, columnar crystal structure, and recrystallization on the effective thermal conductivity of W. It is found that the effective thermal conductivity increases nonlinearly with increasing grain size, and a simple correlation of converting two-dimension into three-dimension effective thermal conductivity is obtained. Interestingly, the effective thermal conductivity of the columnar crystal is relatively high along the elongated direction and higher than that of the isometric crystal. Nevertheless, the effective thermal conductivity decreases with the occurrence of the recrystallization due to the increased grain boundary density. Our results reveal that grain growth and grain structure can affect the capacity of heat transfer at high temperatures, which could be considered in the transient event of the long-time service of W materials in fusion devices.
Liquefaction performances of the mixture of paper fibre and LDPE in subcritical water
Authors: Guan Chunxing , Wang Ying , Zong Xiuyu , Zhang Pu , Hui Fan , Gong Hao , Wang Yuzhen
Published: March 2022

The waste Tetra pack impose a great pressure on environment. In this paper, we use hydrothermal liquefaction technique to convert it into valuable crude oil. The paper fibre and LDPE were studied in supercritical water at 420 °C, 25 MPa and residence time of 30 min. Effect of paper fibre: LDPE on the crude oil yield, components distribution and high heat value were investigated in depth. Results showed that maximum crude oil yield of 27.33 wt% was obtained at paper fibre to LDPE of 8:2, minimum O/C of 0.094 was obtained at paper fibre to LDPE of 5:5, which reflect that HTL of paper fibre and LDPE had a synergetic effect. And the highest high heat value of the crude oil reach 37.7 MJ/kg at the ratio of 5:5• The CH radicals produced from LDPE chain can promote the hydrogenation reaction that then decrease the production of oxygen-containing groups, and also the broken of C-C bond in lignin will be accelerate, which increased the diesel (C16-C47) compound.
Analysis of the thermal process of hot oil pipeline shutdown and restart
Authors: Zheng Zhan , Mengyao Xu , Xiaohu Chang , Duolong Gao , Yuqi Zhang
Published: March 2022

For a long transport pipeline in service in the east, the thermodynamic change rules along the pipeline during shutdown and restart were simulated and analyzed respectively, and the characteristics of soil temperature field during restart were clarified. The change of the dangerous section position was analyzed emphatically, and the reasonable shutdown time was determined according to the temperature of the dangerous section position. The research of this paper can provide theoretical support for the determination of shutdown time in the process of shutdown.
Analysis of factors affecting thermal recovery of porous media in heavy oil reservoir
Authors: Zhong Rongqiang , Yao Lirong , Zhao Yi , Zhao Deyin , Li Zhenjia
Published: March 2022

In the process of hot recovery of heavy oil, there are many factors affecting the seepage velocity of porous media in reservoir, which can be broadly divided into geological factors and development factors. Among geological factors, reservoir permeability is an important factor affecting oil recovery by water drive, and injection-production inlet pressure and injection-production temperature are also very important. Numerical simulation is used to study the variation of permeability velocity and temperature of porous media in reservoir. The numerical simulation results show that with the increase of porous media permeability, the time for the reservoir porous media to reach stability becomes shorter, and the permeability of the reservoir shows an obvious trend of acceleration. Under the same conditions, the larger the volume fraction is, the larger the volume occupied by solids will be, leading to the smaller skeleton cross section of reservoir porous media, which will weaken the ability of fluid to pass through the porous media. When the viscosity of heavy oil is high, the thermal recovery effect will be reduced. Increasing the injection pressure of injection-production fluid can effectively increase the flow velocity of fluid in porous media.
The affection of Crude Oil Physical Parameters on Heat Transfer
Authors: Jining Liu , Deyin Zhao , Yi Zhao , Rongqiang Zhong , Lirong Yao , Zhenjia Li
Published: March 2022

This paper used the partition method mathematical model, considering the oil’s latent heat effects and the cyclical changes of atmospheric temperature, studied on the influence of crude oil properties on heat and mass transfer during the process of shutdown in overhead pipe. This paper used UFD method to simulate the internal temperature field in shutdown overhead pipe with different crude oil’s physical parameters, and gave the solidification cloud charts of medium in typical shutdown time.
A review of hydrogen-based hybrid renewable energy systems: Simulation and optimization with artificial intelligence
Authors: Cai Wenchao , Li Chenglong , Agbossou Kodjo , Bénard Pierre , Xiao Jinsheng
Published: March 2022

With the massive use of traditional fossil fuels, greenhouse gas emissions are increasing, and environmental pollution is becoming an increasingly serious problem, which led to an imminent energy transition. Therefore, the development and application of renewable energy are particularly important. This paper reviews a wide range of issues associated with hybrid renewable energy systems (HRESs). The issues concerning system configurations, energy storage options, simulation and optimization with artificial intelligence are discussed in detail. Storage technology options are introduced for stand-alone (off-grid) and grid-connected (on-grid) HRESs. Different optimization methodologies, including classical techniques, intelligent techniques, hybrid techniques and software tools for sizing system components, are presented. Besides, the artificial intelligence methods for optimizing the solar/wind HRESs are discussed in detail.
Soot formation in methane-ethylene binary fuel combustion with hydrogen addition
Authors: Wang Y , Gu M Y , Cao L
Published: March 2022

A numerical investigation of soot formation was conducted by applying the reactive molecular dynamics, and the chemical effect of H2 addition on the soot formation was explored. It was found that a higher initial methane ratio under the same hydrogen doping ratio could accelerate the rate of methane consumption and hydrogen generation As the proportion of methane in the methane-ethylene binary fuel increased, the chemical effect of H2 on the carbon number of the largest soot particles gradually weakened. Quantitative analysis showed that there was almost no coupling effect of hydrogen addition in the methane-ethylene binary fuel.
Fault detection and diagnosis of GCPV systems using bayesian neural network
Authors: Kara Mostefa Khelil C , Amrouche B , Kara K
Published: March 2022

At present, artificial neural networks are massively and successfully used for faults diagnosis of grid connected PV (GCPV) systems thanks to their capabilities of learning and generalization. In fact, the use of ANN permits the development of intelligent algorithms that can learn all the PV systems working status and then be able to detect and identify possible malfunctions status and causes independently of the ANNs type. However each type of ANN owns its proper characteristics from point of view of its accuracy, efficiency, reliability as well as its response of time in term of faults detection and diagnosis compared to others. In this article, fault detection and diagnosis of small GCPV array based on experimental setup using Bayesian Neural Network is presented. This type of Artificial Neural Network can secure the identification and localization of the greatest recurring cases in PV generator in particular short-circuit, open-circuit and healthy cases. This study requires four input data: irradiation, cell temperature, current and voltage of maximum power point. Results show that, this study proved an excellent level of accuracy displaying (99.88%) in term of detection and localization of treated faults with global response time equals to 16 min22.
Investigation of Hydrogen Dispersion Characteristics with Liquid Helium Spills
Authors: Shu Z Y , Lei G , Liang W Q , Wang T X , Qian H
Published: March 2022

Liquid hydrogen is an important way for hydrogen energy storage and transportation in the future. However, the safety issue should be a concern because it will quickly form a low- temperature, flammable and explosive vapor cloud when liquid hydrogen leaks. A new liquid helium spill experiment method was used to predict the dispersion characteristics of liquid hydrogen in confined space at this work. The concentration cloud and the infrared cloud images near the liquid helium pool were obtained at the same time. Results show it is a safe and reliable way to study the leakage and diffusion characteristics of liquid hydrogen instead of liquid helium. After the liquid helium leaks and diffuses, a white cloud cluster will quickly form, and the vapor cloud cluster has a clear temperature boundary observed by infrared thermal imaging equipment. The concentration decay rate of the helium concentration near the leakage port along the vertical height is less than the concentration decay rate of the horizontal distance, which are 0.098%/mm and 0.118%/mm, respectively. The research results have certain technical guidance for the application and safety protection of liquid hydrogen.
Potential, attainable, and current levels of global crop diversity
Authors: Aramburu Merlos Fernando , Hijmans Robert J
Published: March 2022

High levels of crop species diversity are considered beneficial. However, increasing diversity might be difficult because of environmental constraints and the reliance on a few major crops for most food supply. Here we introduce a theoretical framework of hierarchical levels of crop diversity, in which the environmental requirements of crops limit potential diversity, and the demand for agricultural products further constrain attainable crop diversity. We estimated global potential, attainable, and current crop diversity for grid cells of 86 km2. To do so, we first estimated cropland suitability values for each of 171 crops, with spatial distribution models to get estimations of relative suitability and with a crop model to estimate absolute suitability. We then used a crop allocation algorithm to distribute the required crop area to suitable cropland. We show that the attainable crop diversity is lower in temperate and continental areas than in tropical and coastal regions. The diversity gap (the difference between attainable and current crop diversity) is particularly large in most of the Americas and relatively small in parts of Europe and East Asia. By filling these diversity gaps, crop diversity could double on 84% of the world’s agricultural land without changing the aggregate amount of global food produced. It follows that while there are important regional differences in attainable diversity, specialization of farms and regions is the main reason for low levels of local crop diversity across the globe, rather than our high reliance on a few crops.
Mean area of the convex hull of a run and tumble particle in two dimensions
Authors: Singh Prashant , Kundu Anupam , Majumdar Satya N , Schawe Hendrik
Published: March 2022

We investigate the statistics of the convex hull for a single run-and-tumble particle (RTP) in two dimensions. RTP, also known as the persistent random walker, has gained significant interest in the recent years due to its biological application in modelling the motion of bacteria. We consider two different statistical ensembles depending on whether (i) the total number of tumbles n or (ii) the total observation time t is kept fixed. Benchmarking the results on the perimeter, we study the statistical properties of the area of the convex hull for a RTP. Exploiting the connections to extreme value statistics, we obtain exact analytical expressions for the mean area for both ensembles. For fixed-t ensemble, we show that the mean area possesses a scaling form in γt (with γ being the tumbling rate) and the corresponding scaling function is exactly computed. Interestingly, we find that it exhibits a crossover from ∼t
3 scaling at small times

t
≪

γ

−
1

to ∼t scaling at large times

t
≫

γ

−
1

. On the other hand, for fixed-n ensemble, the mean expectedly grows linearly with n for n ≫ 1. All our analytical findings are supported with the numerical simulations.
Mechanical Performance of Mortar and Concrete Using Borneo Wood Sawdust as Replacement of Fine Aggregate
Authors: Prasetia I , Putera D P , Pratiwi A Y
Published: March 2022

This study aims to analyze the utilization of wood sawdust from Borneo Island as a replacement for fine aggregate. For that purpose, two types of sawdust will be used, which are sawdust from ulin wood (Eusideroxylon Zwageri) and meranti wood (Shorea spp.). Subsequently, to test the effectiveness of replacing fine aggregate with sawdust, the compressive strength tests were carried out for mortar and concrete samples. Furthermore, the fine aggregate replacement ratio in all samples was set to 2.5% and 5% for both types of sawdust. Moreover, samples were also made by adding 0.5 kg/m3 and 1 kg/m3 of ulin and meranti sawdust to the concrete mixture. The compressive strength results of mortar samples show that sawdust from ulin wood has a better effect compared to meranti wood. In addition, the combination of sawdust from ulin and meranti gave a better effect in increasing the strength of the mortar samples. The same pattern could also be observed in the concrete samples, where ulin wood sawdust provides a good strength-enhancing effect, especially when used as an addition to the fine aggregate. Therefore, it is highly recommended to use sawdust, especially from ulin wood, as a material for making green concrete.
Optimisation of Recoverable Horizontal Deformation and Size Ratio of Compacted Rubberized Stone Mastic Asphalt Based on Rubber and Binder Contents Using Response Surface Methodology
Authors: Noura Sajjad , Al Sabaeei Abdulnaser M. , Ismat Gailan , Mirzapour Mounes Sina , Muniandi Ratnasamy , Al-Mansob Ramez , Carter Alan
Published: March 2022

The use of waste materials such as rubber powder in stone mastic asphalt (SMA) has improved the structural performance to some extent, and the research on the improvement is still ongoing. Rubberised stone mastic asphalt has shown good performance in terms of resilient modulus. In this research, response surface methodology was utilised to increase the efficiency in determining the recoverable horizontal deformation and samples compaction level using optimum rubber and binder content. Thirty-one tests were performed on different binders and rubber contents, and the recoverable horizontal deformation and ratio of height to the diameter of Marshall compacted samples were recorded. The ANOVA analysis showed a low P-value with a high correlation coefficient, and the optimisation showed that adding almost 3% rubber powder to SMA could improve the compaction level and desirable recoverable deformation.
The Feasibility and Performance of Self Compacting Concrete on Various Size and Proportion of Locally Coarse Aggregate
Authors: Chairunnisa N , Krasna W A , Nurdiansyah D
Published: March 2022

Self-compacting concrete (SCC) is an innovation concrete technology which can spread grout of concrete into the formwork without the need of vibrator. The objective of this research was to evaluate the performance of SCC using locally available coarse aggregate sizes, proportion from total aggregate weight and chemical admixtures in producing of SCC. Two various sizes and percentages of coarse aggregates from total aggregate weight were investigated The influence of coarse aggregate size and proportion is determined in terms of fresh concrete and compressive strength under constant dosage of superplasticizer. Result of the research indicated that increasing the size of coarse aggregate in SCC mixtures from size of 10 mm to 12.5 mm can produce poor fairly mixtures in terms passing ability for both of specimens using 40% and 50% of coarse aggregate content in the SCC mixtures. Moreover, the augment of the volume content of coarse aggregate from 40% to 50% of total aggregate weight can improve the concrete compressive strength and the adding of superplasticizer in the mixtures can avoid segregation among aggregate particles. The result of experimental phase indicated that the equation from ACI 209R-92 can be utilized to predict the compressive strength of SCC mixtures at different ages
Utilization of Coconut Shell Ash as a Substitute Material in Paving Block Manufacturing
Authors: Nurwidayati R , Azima N N
Published: March 2022

In this study, coconut shell ash (CSA) was used as a substitute for cement in the manufacture of paving blocks. The research aims to determine the CSA substitution effect on the mortar compressive strength. The replacement percentages were 0, 3, 5, 8, 10, and 12%. The immersed and wrapping with plastic were conducted as curing conditions. The mortar compressive strength was 24.97, 16.44, 15.26, 14.61, 14.25, 11.87 MPa for immersed curing at 28 days for 0, 3, 5, 8, 10, and 12%, respectively. While for wrapping plastic, the compressive strength was 21.97, 15.82, 15.10, 14.06, 13.21, and 12.62 MPa. Substitution of coconut shell ash reduced the compressive strength. Based on the optimum compressive strength of mortar, the paving block size of 20x10x6 cm was made and then cut into 6x6x6 cm. The compressive strength was 13.21, 12.02, and 9.65 MPa at the 0, 3, and 5% CSA substitution. The water absorption indicated almost similar around 7% for all substitutions. There were no defects such as cracks found, and the different weights before and after immersed in sodium sulfate were 0.1 to 0.3%.
Variability of Discharge Inflow in Wonorejo Reservoir, Indonesia
Authors: Margini Nastasia F. , Wardoyo Wasis , Anwar Nadjadji
Published: March 2022

Discharge variability such as frequency and magnitude at certain seasons has the main control on the hydrological behavior of the river. This means a better understanding of discharge variability for reservoir inflow it can be used to manage water reservoir manajement more effectively during the wet year we can use more water, and during the dry season water saving must be done. This flow discharge variation was investigated using data for 18 years from 2003 to 2020 using data on the daily inflow gate of the Wonorejo Reservoir. This study was used to examine the Standardized Precipitation Index (SPI) and statistical methods in the form of average annual discharge, standard deviation (SD), and coefficient of variation (CV) were used to determine the relationship between rain and discharge that occurred. The results of this study show the variability of the discharge for wet, normal and dry years, as well as the distribution of, and changes in the stream flow record. This study is very valuable in order to know the trend of seasonal discharge that occurs, the estimated highest and lowest discharge, as well as the annual discharge cycle in the context of water resources management. Thus, the inflow discharge of the Wonorejo Reservoir from January 2003 to December 2020 shows that each time series follows a normal distribution with a probability percentage of a wet year and a dry year of 41% while a normal year is 11%.
Eco-design concept of street corridors as a city image forming
Authors: Amir Sjafril , Bonifacius Nurhamdoko , Poerwoningsih Dina
Published: March 2022

Street corridor landscape is an important part of open space for city sustainability but is often neglected in urban development. Road corridors, connecting urban spaces can act as city gates because they provide a visual impact on the city. Urban road corridors are places for people with different social backgrounds, ages, and genders to engage in activities. The road corridor should play an important role in shaping the image of the city because it becomes a visual display case for the city gate. This article aims to find out the researchers’ views on the eco-design concept of road corridor landscapes that form the image of the city. The eco-design concept was proposed as an answer to the environmental, energy efficiency, and sustainability issues that are currently emerging, this is in line with the objectives of the Sustainable Development Goals. This paper uses a qualitative descriptive method, describing secondary data from research journals about the concept of ecodesign. The conclusion shows that the urban road corridor landscape can be arranged and improved with an eco-design concept strategy to improve the image of the city towards a sustainable city.