Embedded Atom Method-Based Geometry Optimization Aspects of Body-Centered Cubic Metals

We present embedded atom method-based geometry optimization calculations for Fe, Cr, Mo, Nb, Ta, V and W body-centered cubic metals with Finnis–Sinclair potentials. After the optimization, we determine their typical elastic constants, bulk modulus, shear modulus, Young's modulus, Poisson's ratios, elastic wave velocities and cohesive energies. Additionally, we perform a benchmark between the experiments and the available density functional theory results. In general, our results show a good consistency with previous findings on the elastic and cohesive energy properties of the considered metals.

Formation Mechanism and Binding Energy for Body-Centered Cubic Structure of He^＋9 Cluster

The formation mechanism for the body-centered cubic structure of He+ cluster is proposed and its totalenergy curve is calculated by the method of a Modified Arrangement Channel Quantum Mechanics. The energy is thefunction of separation R between the nuclei at the center and an apex of the body-centered cubic structure. The resultof the calculation shows that the curve has a minimal energy -25.6669 (a.u.) at R -- 2.550ao. The binding energy ofHe+ with respect to He^++8He was calculated to be 0.8857 a.u. This means that the cluster of He^+9 may be formed inthe body-centered cubic structure of R=2.55ao.

Current development of body-centered cubic high-entropy alloys for nuclear applications

High-entropy alloys greatly expand the alloy design range and offer new possibilities for improving material performance.Based on the worldwide research efforts in the last decade,the excellent mechanical properties and promising radiation and corrosion resistance of this group of materials have been demonstrated.High-entropy alloys with body-centered cubic(BCC)structures,especially refractory high-entropy alloys,are considered as promising materials for high-temperature applications in advanced nuclear reactors.However,the extreme reactor conditions including high temperature,high radiation damage,high stress,and complex corrosive environment require a comprehensive evaluation of the material properties for their actual service in nuclear reactors.This review summarizes the current progress on BCC high-entropy alloys from the aspects of neutron economy and activation,mechanical properties,high-temperature stability,radiation resistance,as well as corrosion resistance.Although the current development of BCC high-entropy alloys for nuclear applications is still at an early stage as the large design space of this group of alloys has not been fully explored,the current research findings provide a good basis for the understanding and prediction of material behaviors with different compositions and microstructures.Further in-depth understanding of the degradation mechanisms and characterization of material properties in response to conditions close to reactor environment are necessary.A critical down-selection of potential candidates is also crucial for further comprehensive evaluation and engineering validation.

Ab initio modeling of the energy landscape for screw dislocations in body-centered cubic high-entropy alloys

In traditional body-centered cubic(bcc)metals,the core properties of screw dislocations play a critical role in plastic deformation at low temperatures.Recently,much attention has been focused on refractory high-entropy alloys(RHEAs),which also possess bcc crystal structures.However,unlike face-centered cubic high-entropy alloys(HEAs),there have been far fewer investigations into bcc HEAs,specifically on the possible effects of chemical short-range order(SRO)in these multiple principal element alloys on dislocation mobility.Here,using density functional theory,we investigate the distribution of dislocation core properties in MoNbTaW RHEAs alloys,and how they are influenced by SRO.The average values of the core energies in the RHEA are found to be larger than those in the corresponding pure constituent bcc metals,and are relatively insensitive to the degree of SRO.However,the presence of SRO is shown to have a large effect on narrowing the distribution of dislocation core energies and decreasing the spatial heterogeneity of dislocation core energies in the RHEA.It is argued that the consequences of the mechanical behavior of HEAs is a change in the energy landscape of the dislocations,which would likely heterogeneously inhibit their motion.

A novel rapid cooling assembly design in a high-pressure cubic press apparatus

In traditional high-pressure–temperature assembly design, priority has been given to temperature insulation and retention at high pressures.This limits the efficiency of cooling of samples at the end of experiments, with a negative impact on many studies in high-pressure Earth andplanetary science. Inefficient cooling of experiments containing molten phases at high temperature leads to the formation of quench textures,which makes it impossible to quantify key compositional parameters of the original molten phase, such as their volatile contents. Here,we present a new low-cost experimental assembly for rapid cooling in a six-anvil cubic press. This assembly not only retains high heatingefficiency and thermal insulation, but also enables a very high cooling rate (∼600 ℃/s from 1900 ℃ to the glass transition temperature).Without using expensive materials or external modification of the press, the cooling rate in an assembly (∼600 ℃/s) with cube lengths of38.5 mm is about ten times faster than that in the traditional assembly (∼60 ℃/s). Experiments yielding inhomogeneous quenched melttextures when the traditional assembly is used are shown to yield homogeneous silicate glass without quench textures when the rapid coolingassembly is used.

Synthesizing active and durable cubic ceria catalysts(<6 nm)for fast dehydrogenation of bio-polyols to carboxylic acids coproducing green H_(2)

Dehydrogenation is considered as one of the most important industrial applications for renewable energy.Cubic ceria-based catalysts are known to display promising dehydrogenation performances in this area.Large particle size(>20 nm)and less surface defects,however,hinder further application of ceria materials.Herein,an alternative strategy involving lactic acid(LA)assisted hydrothermal method was developed to synthesize active,selective and durable cubic ceria of<6 nm for dehydrogenation reactions.Detailed studies of growth mechanism revealed that,the carboxyl and hydroxyl groups in LA molecule synergistically manipulate the morphological evolution of ceria precursors.Carboxyl groups determine the cubic shape and particle size,while hydroxyl groups promote compositional transformation of ceria precursors into CeO_(2) phases.Moreover,enhanced oxygen vacancies(Vo)on the surface of CeO_(2) were obtained owing to continuous removal of O species under reductive atmosphere.Cubic CeO_(2) catalysts synthesized by the LA-assisted method,immobilized with bimetallic PtCo clusters,exhibit a record high activity(TOF:29,241 h^(-1))and Vo-dependent synergism for dehydrogenation of bio-derived polyols at 200℃.We also found that quenching Vo defects at air atmosphere causes activity loss of PtCo/CeO_(2) catalysts.To regenerate Vo defects,a simple strategy was developed by irradiating deactivated catalysts using hernia lamp.The outcome of this work will provide new insights into manufacturing durable catalyst materials for aqueous phase dehydrogenation applications.

Metastable face-centered cubic ruthenium-based binary alloy for efficient alkaline hydrogen oxidation electrocatalysis

Metastable nanostructured electrocatalyst with a completely different surface environment compared to conventional phase-based electrocatalyst often shows distinctive catalytic property.Although Ru-based electrocatalysts have been widely investigated toward hydrogen oxidation reaction(HOR)under alkaline electrolytes,these studies are mostly limited to conventional hexagonal-close-packed(hcp)phase,mainly arising from the lack of sufficient synthesis strategies.In this study,we report the precise synthesis of metastable binary RuW alloy with face-centered-cubic(fcc)phase.We find that the introduction of W can serve as fcc phase seeds and reduce the formation energy of metastable fcc-RuW alloy.Impressively,fcc-RuW exhibits remarkable alkaline HOR performance and stability with the activity of 0.67 mA cm_(Ru)^(-2)which is almost five and three times higher than that of hcp-Ru and commercial Pt/C,respectively,which is attributed to the optimized binding strength of adsorbed hydroxide intermediate derived from tailored electronic structure through W doping and phase engineering.Moreover,this strategy can also be applied to synthesize other metastable fcc-RuCr and fcc-RuMo alloys with enhanced HOR performances.

Author Correction:High energy barriers for edge dislocation motion in body-centered cubic high entropy alloys

The original version of this Article contained an error in the Acknowledgements:‘Project 200021_18198/1’should have read‘Project 200021_181987/1’.This has now been corrected in both the PDF and HTML versions of the Article.

ANovel Non-Isolated Cubic DC-DC Converter with High Voltage Gain for Renewable Energy Power Generation System

In recent years,switched inductor(SL)technology,switched capacitor(SC)technology,and switched inductor-capacitor(SL-SC)technology have been widely applied to optimize and improve DC-DC boost converters,which can effectively enhance voltage gain and reduce device stress.To address the issue of low output voltage in current renewable energy power generation systems,this study proposes a novel non-isolated cubic high-gain DC-DC converter based on the traditional quadratic DC-DC boost converter by incorporating a SC and a SL-SC unit.Firstly,the proposed converter’s details are elaborated,including its topology structure,operating mode,voltage gain,device stress,and power loss.Subsequently,a comparative analysis is conducted on the voltage gain and device stress between the proposed converter and other high-gain converters.Then,a closed-loop simulation system is constructed to obtain simulation waveforms of various devices and explore the dynamic performance.Finally,an experimental prototype is built,experimental waveforms are obtained,and the experimental dynamic performance and conversion efficiency are analyzed.The theoretical analysis’s correctness is verified through simulation and experimental results.The proposed converter has advantages such as high voltage gain,low device stress,high conversion efficiency,simple control,and wide input voltage range,achieving a good balance between voltage gain,device stress,and power loss.The proposed converter is well-suited for renewable energy systems and holds theoretical significance and practical value in renewable energy applications.It provides an effective solution to the issue of low output voltage in renewable energy power generation systems.

The Theoretical Principles of the Body-Centered Therapy to Promote Affective Attunement in Children with Autism Spectrum Disorder

Background: The roots of autism spectrum disorders become evident in first attunement mechanisms between mother and child that allow a first level of mentalizing. Neurosciences and current developmental theories confirm the existence of defensive mechanisms related to body and affectivity that psychodynamic theories had already highlighted. Reading child’s behavior not only by administering tests but also through careful clinical observations allows a better understanding of the communication and social difficulties present in autistic children. The identification of the zone of proximal development can promote a therapeutic intervention that respects the individuality of the child and the specificity of his relational approach to the world. Conclusion: The paper presents the theoretical principles of a body-centered therapy to promote the attunement processes necessary to activate cognitive resources.

Transformation of Hexagonal Lu to Cubic LuH_(2+x)Single-Crystalline Films

With the recent report of near ambient superconductivity at room temperature in the N-doped lutetium hydride(Lu-H-N)system,the understanding of cubic Lu-H compounds has attracted worldwide attention.Generally,compared to polycrystals with non-negligible impurities,the single-crystalline form of materials with high purity can provide an opportunity to show their hidden properties.However,the experimental synthesis of single-crystalline cubic Lu-H compounds has not been reported so far.Here,we develop an easy way to synthesize highly pure LuH_(2+x)single-crystalline films by the post-annealing of Lu single-crystalline films(purity of 99.99%)in H_(2)atmosphere.The crystal and electronic structures of films were characterized by x-ray diffraction,Raman spectroscopy,and electrical transport.Interestingly,Lu films are silver-white and metallic,whereas their transformed LuH_(2+x)films become purple-red and insulating,indicating the possible formation of an unreported electronic state of Lu-H compounds.Our work provides a novel route to synthesize and explore more singlecrystalline Lu-H compounds.

Cubic Ice Captured by In Situ Transmission Electron Microscope

Nearly a hundred years ago,the Nobel laureate Linus Pauling proposed based on the'ice rule'[1]and residual entropy theory that the structural entropy of ice is the same for common hexagonal ice(Ih)with tetrahedrally coordinated water molecules assembling into a hexagonal close-packing manner and cubic ice(ice Ic)in a cubic closepacking manner.[2]

CONFORMALLY FLAT AFFINE HYPERSURFACES WITH SEMI-PARALLEL CUBIC FORM

In this paper,we study locally strongly convex affine hypersurfaces with the vanishing Weyl curvature tensor and semi-parallel cubic form relative to the Levi-Civita connection of the affine metric.As a main result,we classify these hypersurfaces as not being of a flat affine metric.In particular,2 and 3-dimensional locally strongly convex affine hypersurfaces with semi-parallel cubic forms are completely determined.

Coupled CUBIC Congestion Control for MPTCP in Broadband Networks

Recently,multipath transmission control protocol(MPTCP)was standardized so that data can be transmitted through multiple paths to utilize all available path bandwidths.However,when high-speed long-distance networks are included in MPTCP paths,the traffic transmission performance of MPTCP is severely deteriorated,especially in case the multiple paths’characteristics are heavily asymmetric.In order to alleviate this problem,we propose a“Coupled CUBIC congestion control”that adopts TCP CUBIC on a large bandwidth-delay product(BDP)path in a linked increase manner for maintaining fairness with an ordinary TCP traversing the same bottleneck path.To verify the performance excellence of the proposed algorithm,we implemented the Coupled CUBIC Congestion Control into Linux kernels by modifying the legacy MPTCP linked-increases algorithm(LIA)congestion control source code.We constructed asymmetric heterogeneous network testbeds mixed with large and small BDP paths and compared the performances of LIA and Coupled CUBIC by experiments.Experimental results show that the proposed Coupled CUBIC utilizes almost over 80%of the bandwidth resource in the high BDP path,while the LIA utilizes only less than 20%of the bandwidth for the same path.It was confirmed that the resource utilization and traffic transmission performance have been greatly improved by using the proposed Coupled CUBIC in high-speed multipath networks,as well as maintaining MPTCP fairness with competing single-path CUBIC or Reno TCP flows.

Source Quantitative Identification by Reference-Based Cubic Blind Deconvolution Algorithm

The semi-blind deconvolution algorithm improves the separation accuracy by introducing reference information.However,the separation performance depends largely on the construction of reference signals.To improve the robustness of the semi-blind deconvolution algorithm to the reference signals and the convergence speed,the reference-based cubic blind deconvolution algorithm is proposed in this paper.The proposed algorithm can be combined with the contribution evaluation to provide trustworthy guidance for suppressing satellite micro-vibration.The normalized reference-based cubic contrast function is proposed and the validity of the new contrast function is theoretically proved.By deriving the optimal step size of gradient iteration under the new contrast function,we propose an efficient adaptive step optimization method.Furthermore,the contribution evaluation method based on vector projection is presented to implement the source contribution evaluation.Numerical simulation analysis is carried out to validate the availability and superiority of this method.Further tests given by the simulated satellite experiment and satellite ground experiment also confirm the effectiveness.The signals of control moment gyroscope and flywheel were extracted,respectively,and the contribution evaluation of vibration sources to the sensitive load area was realized.This research proposes a more accurate and robust algorithm for the source separation and provides an effective tool for the quantitative identification of the mechanical vibration sources.

Large Eddy Simulations of Rayleigh-Bénard Convection in a Cubic Cavity

This paper conducts a Large Eddy Simulation (LES) of Rayleigh Bénard convection in a cubic cavity based on the WMLES S-Omega subgrid-scale model. For a cubic cavity with a vertical temperature difference of 6.7°C and 20°C, the velocity pulsation profiles and the mean velocity profiles of the vertical section in the middle of the cubic cavity were simulated, respectively. And they are consistent with the experiment results. Furthermore, the mean velocity field of the vertical cross-section in the middle of the cavity was calculated. Structures of the mean velocity field in the two cases are similar. A counterclockwise large vortex is found to occupy the cavity, and there are two small clockwise vortices in the lower left and upper right corners, and the mean velocity fields at two different temperature differences are consistent with the experimental results. The two-dimensional instantaneous temperature field and mean temperature field with different cross-sections in the z-direction, as well as the three-dimensional instantaneous isothermal surface structure, indicate that the large-scale circulation motion within the cubic cavity is moving diagonally. In addition, the structure of the mean streamline also illustrates this viewpoint. For the reverse vortex formed at two corners in the mean streamline structure, we used the Q criterion to identify and obtain two vortex structures similar to boomerangs. The basic turbulent structure in RB thermal convection includes the rising and falling plumes generated by buoyancy effects.

基于Cubic的QUIC拥塞控制算法研究与改进

为了解决单一的快速UDP网络连接(quick UDP internet connections,QUIC)拥塞控制算法导致网络利用率大幅度降低、丢包容忍度较差、网络资源利用不够充分等问题,对QUIC源码中常用的Cubic拥塞控制算法进行研究,提出了一种基于丢包和时延相结合的拥塞控制方法,从而达到充分利用带宽、提高网络吞吐量的目的,以期为相关研究人员提供参考。

双种群协同演化的改进蜜獾算法

针对蜜獾算法存在的局部搜索能力不足、易陷入局部最优值等问题,提出一种双种群协同演化的改进蜜獾算法。在初始化阶段采用Cubic混沌映射对种群进行初始化,扩大可行解的搜索范围并提高种群的分布均衡性;引入融合黏菌算法和蜜獾算法的双种群优化机制,依托两者的更新优势协同推进个体逼近目标位置,进而提高整个算法的搜索效率和优化性能;采用柯西随机反向扰动策略对蜜獾种群最优位置进行扰动,以提高算法跳出局部最优的能力。通过评估单一策略的改进有效性实验、与七种对比算法的不同高维实验以及Wilcoxon秩和检验,结果表明该算法具有良好的收敛精度和求解速度。最后将改进算法应用于压缩弹簧设计和压力容器设计问题,进一步验证了改进策略的有效性及该算法的工程实用性。

国家天然气(页岩气)千亿立方米级产能基地共建共享模式

国家天然(页岩气)千亿立方米级产能基地建设是保障国家能源安全、支撑区域社会经济加快发展的重大战略。在借鉴油气共建共享成功经验基础上,构建了国家天然气(页岩气)千亿立方米级产能基地共建共享模式,提出了模式实施路径。研究结果表明:①国家天然气(页岩气)千亿立方米级产能基地建设涉及庞大的产业体系与多元主体不同利益诉求,需要以共建共享理念和系统工程思维为指引,立足多元主体与多维度要素协同构建共建共享模式。②模式实施五大路径:强化共建共享顶层战略设计,丰富发展政企共建共享方式,完善企业之间共建共享机制,畅通多元主体沟通协商渠道,健全共建共享应急预警体系。结论认为,该模式以战略视域统筹产能基地建设,能够实现对多元主体利益的有效协同,促进天然气(页岩气)资源开发利用与产业链价值提升,为带动区域社会经济发展并推进共同富裕提供有力支持。

紫外可见波长溶液标准物质的研制

以紫外可见区无吸收的高氯酸溶液作为空白基体,利用稀土元素钬和钕在紫外可见光区丰富的光谱特征吸收,研制一种可以覆盖200~900nm的紫外可见区的波长溶液标准物质。采用对峰值点附近进行3次样条插值进行数据处理,并以插值后的峰值数据作为峰值波长,分辨力可到小数点后两位。经过均匀性和稳定性检验,由9家实验室采用高精度紫外可见分光光度计对该标准物质进行协同定值,并进行不确定度评定。结果表明,该标准物质均匀性良好,在25℃下保存稳定性在1年以上。该标准物质可应用于光谱光度测量仪器的波长校准和期间核查等。