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Flexural-torsional buckling behavior of aluminum alloy beams

Xiaonong GUO,Zhe XIONG,Zuyan SHEN

《结构与土木工程前沿（英文）》 2015年第9卷第2期页码 163-175 doi: 10.1007/s11709-014-0272-8

摘要： This paper presents an investigation on the flexural-torsional buckling behavior of aluminum alloy beams (AAB). First, based on the tests of 14 aluminum alloy beams under concentrated loads, the failure pattern, load-deformation curves, bearing capacity and flexural-torsional buckling factor are studied. It is found that all the beam specimens collapsed in the flexural-torsional buckling with excessive deformation pattern. Moreover, the span, loading location and slenderness ratio influence the flexural-torsional buckling capacity of beams significantly. Secondly, besides the experiments, a finite element method (FEM) analysis on the flexural-torsional buckling behavior of AAB is also conducted. The main parameters in the FEM analysis are initial imperfection, material property, cross-section and loading scheme. According to the analytical results, it is indicated that the FEM is reasonable to capture mechanical behavior of AAB. Finally, on the basis of the experimental and analytical results, theoretical formulae to estimate the flexural-torsional buckling capacity of AAB are proposed, which could improve the application of present codes for AAB.

关键词： flexural-torsional buckling aluminum alloy beams (AAB) finite element method (FEM) theoretical formula

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单缝桥梁在温度作用下的结构受力计算

赵怡彬,邵旭东

《中国工程科学》 2012年第14卷第10期页码 103-112

摘要：

桥台处伸缩缝问题是长期困扰工程界的难题，它会带来跳车、桥梁局部损坏、伸缩缝装置经常更换等各种问题。为有效解决这一问题，提出了一种适用于大中型桥梁的新型结构体系——单伸缩缝桥梁（单缝桥）。在考虑接线路面裂缝开展的情况下，建立了温度作用下单缝桥的简化计算模型，推导了单缝桥受力、变形的理论公式，用Fortran90编制程序，进行计算。以一座总长280 m的单缝梁桥为例，温度降低20 ℃时，接线路面钢筋最大应力为148 MPa，最大裂缝宽度为0.185 mm，符合规范要求；台后结构对主梁产生的附加应力仅为0.105 MPa，影响很小。通过对影响单缝桥性能的因素：支座类型、配筋率、接线路面长度、摩擦系数、土体刚度、桥长、温差等进行分析，绘制图表，得到以下主要结论：温降时，接线路面受拉，混凝土开裂，是较不利的状况；30 m长的接线路面可以满足结构受力和变形的需要；选择摩擦系数较小的支座和减少接线路面与垫层的摩擦力可以减少结构内力，在接线路面与垫层间推荐加铺土工格栅。

关键词：单缝桥梁温度作用受力与变形理论公式参数分析

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分形方法导出改进的牛顿第二定律及万有引力定律

付昱华

《中国工程科学》 2003年第5卷第6期页码 55-58

摘要：

牛顿第二定律及万有引力定律是根据实验结果总结出来的。为了探讨从理论上导出这两个定律的可能性，根据能量守恒定律，给出用变维分形方法针对一个实例（小球沿长斜面滚下）导出改进的牛顿第二定律及万有引力定律的方法。具体给出了适用于实例的常维分形结果：改进的万有引力定律F=-GMm / r^1.99989和改进的牛顿第二定律F=ma^1.01458。

关键词：分形方法牛顿第二定律万有引力定律理论推导

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A review on different theoretical models of electrocaloric effect for refrigeration

《能源前沿（英文）》 2023年第17卷第4期页码 478-503 doi: 10.1007/s11708-023-0884-6

摘要： The performance parameters for characterizing the electrocaloric effect are isothermal entropy change and the adiabatic temperature change, respectively. This paper reviews the electrocaloric effect of ferroelectric materials based on different theoretical models. First, it provides four different calculation scales (the first-principle-based effective Hamiltonian, the Landau-Devonshire thermodynamic theory, phase-field simulation, and finite element analysis) to explain the basic theory of calculating the electrocaloric effect. Then, it comprehensively reviews the recent progress of these methods in regulating the electrocaloric effect and the generation mechanism of the electrocaloric effect. Finally, it summarizes and anticipates the exploration of more novel electrocaloric materials based on the framework constructed by the different computational methods.

关键词： electrocaloric effect effective Hamiltonian phase-field modeling different theoretical models

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连轧张力公式的实验验证和分析

张进之,赵厚信,王喆,王保罗

《中国工程科学》 2008年第10卷第4期页码 73-77

摘要：

连轧张力公式是连轧理论和实践的核心问题，该问题国内外都有大量的研究，20世纪60年代笔者推导了连轧张力微分方程、多机架动态张力公式、稳态张力公式，理论上已作过深入、广泛的分析讨论。日本在20世纪70年代对连轧张力公式进行了理论上的推导和实验验证，特别是浅川基男等人的连轧实验结果更为重要。为此引用了浅川基男的实验数据和宝钢2 050 mm热连轧机上的实测数据，验证了连轧张力公式。

关键词：连轧张力公式实验验证解析解定常性

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NOx removal by non-thermal plasma reduction: experimental and theoretical investigations

《化学科学与工程前沿（英文）》 2022年第16卷第10期页码 1476-1484 doi: 10.1007/s11705-022-2165-z

摘要： Green and efficient

N O x

removal at low temperature is still desired.

N O x

removal via non-thermal plasma (NTP) reduction is one of such technique. This work presents the experimental and theoretical study on the

N O x

removal via NTP reduction (NTPRD) in dielectric barrier discharge reactor (DBD). The effect of

O 2

molar fraction on

N O x

species in the outlet of DBD, and effects of

N H 3

/NO molar ratio and discharge power of DBD on

N O x

removal efficiency are investigated. Results indicate that anaerobic condition and higher discharge power is beneficial to direct removal of

N O x

, and the

N O x

removal efficiency can be up to 98.5% under the optimal operating conditions. It is also found that adding

N H 3

is favorable for the reduction of

N O x

N 2

at lower discharge power. In addition, the

N O x

removal mechanism and energy consumption analysis for the NTPRD process are also studied. It is found that the reduced active species (

N ∗

N −

, N⁺,

N 2 ∗

N H 2 +

, etc.) generated in the NTPRD process play important roles for the reduction of

N O x

N 2

. Our work paves a novel pathway for

N O x

removal from anaerobic gas in industrial application.

关键词： ${\rm{NO}}_x $ removal NTP reduction mechanism energy consumption

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以土体应力状态计算边坡安全系数的方法

王国体

《中国工程科学》 2006年第8卷第12期页码 80-84

摘要：

土坡的稳定分析一直是沿着条分法的思路发展的。由于对土体应力状态条件的忽视和条分法本身的缺陷，使得条分法得到的安全系数在工程中的应用面临激烈的挑战。土体不同条件下的应力状态表现为K₀效应和变化，它对坡体的安全度影响不可忽视。笔者以考虑土体应力状态为条件，应用土的库伦强度定律和摩尔-库伦准则，推导出平面土坡的安全系数计算公式，与条分法的安全系数对比结果说明这种方法具有概念明确、计算简便、定性可靠的重要特点，可以直接提供于工程应用和参考。

关键词：侧应力系数K₀ 初始应力状态稳定安全系数公式

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Thermal transport properties of monolayer phosphorene: a mini-review of theoretical studies

Guangzhao QIN, Ming HU

《能源前沿（英文）》 2018年第12卷第1期页码 87-96 doi: 10.1007/s11708-018-0513-y

摘要： Phosphorene, a two-dimensional (2D) elemental semiconductor with a high carrier mobility and intrinsic direct band gap, possesses fascinating chemical and physical properties distinctively different from other 2D materials. Its rapidly growing applications in nano-/opto-electronics and thermoelectrics call for fundamental understanding of the thermal transport properties. Considering the fact that there have been so many studies on the thermal transport in phosphorene, it is on emerging demand to have a review on the progress of previous studies and give an outlook on future work. In this mini-review, the unique thermal transport properties of phosphorene induced by the hinge-like structure are examined. There exists a huge deviation in the reported thermal conductivity of phosphorene in literature. Besides, the mechanism underlying the deviation is discussed by reviewing the effect of different functionals and cutoff distance in calculating the thermal transport properties of phosphorene. It is found that the (vdW) interactions play a key role in the formation of resonant bonding, which leads to long-ranged interactions. Taking into account of the vdW interactions and including the long-ranged interactions caused by the resonant bonding with large cutoff distance are important for getting the accurate and converged thermal conductivity of phosphorene. Moreover, a fundamental insight into the thermal transport is provided based on the review of resonant bonding in phosphorene. This mini-review summarizes the progress of the thermal transport in phosphorene and gives an outlook on future horizons, which would benefit the design of phosphorene based nano-electronics.

关键词： thermal transport phosphorene resonant bonding

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Prediction of the theoretical and semi-empirical model of ambient temperature

Foued CHABANE,Noureddine MOUMMI,Abdelhafid BRIMA,Abdelhafid MOUMMI

《能源前沿（英文）》 2016年第10卷第3期页码 268-276 doi: 10.1007/s11708-016-0413-y

摘要： It is well known that the ambient temperature is a sensitive parameter which has a great effect on biology, technology, geology and even on human behavior. A prediction is a statement about an uncertain event. It is often, but not always, based upon experience or knowledge. Although guaranteed accurate information about the future is in many cases impossible, prediction can be useful to assist in making plans about possible developments. As a result, temperature profiles can be developed which accurately represent the expected ambient temperature exposure that this environment experiences during measurement. The ambient temperature over time is modeled based on the previous and data and using a Lagrange interpolation. To observe the comprehensive variation of ambient temperature the profile must be determined numerically. The model proposed in this paper can provide an acceptable way to measure the change in ambient temperature.

关键词： ambient temperature environment correlation theoretical model semi-empirical

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Theoretical and technological exploration of deep

Heping XIE, Yang JU, Shihua REN, Feng GAO, Jianzhong LIU, Yan ZHU

《能源前沿（英文）》 2019年第13卷第4期页码 603-611 doi: 10.1007/s11708-019-0643-x

摘要： Mining industries worldwide have inevitably resorted to exploiting resources from the deep underground. However, traditional mining methods can cause various problems, e.g., considerable mining difficulty, environmental degradations, and frequent disastrous accidents. To exploit deep resources in the future, the concept of mining must be reconsidered and innovative new theories, methods, and technologies must be applied. To effectively acquire coal resources deeper than 2000 m, new theoretical and technological concepts about deep fluidized mining are required. The limits of mining depth need to be broken to acquire deep-coal resources in an environmentally friendly, safe, and efficient manner. This is characterized by ‘There are no coal on the ground and no men in the coal mine’. First, this paper systematically explains deep fluidized coal mining. Then, it presents a new theoretical concept, including the theories of mining-induced rock mechanics, three-field visualization, multi-physics coupling for transformation, and mining, transformation and transport. It also presents key technological concepts, including those of intelligent, unmanned, and fluidized mining. Finally, this paper presents a strategic roadmap for deep fluidized coal mining. In summary, this paper develops new theoretical and technological systems for accomplishing groundbreaking innovations in mining technologies of coal resources in the deep underground.

关键词： coal resource deep in situ fluidized mining theoretical system key technologies strategic roadmap

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Theoretical analysis and experimental investigation of valveless piezoelectric pump with unsymmetrical

ZHANG Jianhui, LU Jizhuang, XIA Qixiao, LI Hong

《机械工程前沿（英文）》 2007年第2卷第1期页码 13-19 doi: 10.1007/s11465-007-0002-1

摘要： A novel valveless piezoelectric pump with unsymmetrical ridges is presented at first. It ingeniously utilizes the inner space of its chamber by developing its chamber bottom into unsymmetrical ridges along the direction of the inlet and outlet of the pump. Hence, a series of cuneiform channels are asymmetrically and alternately formed between the unsymmetrical ridges and the piezoelectric vibrator, which enables the pump to form a one-way flow instead of the function of the traditional diffuse or nozzle elements fitted outside the chamber. Then, by analyzing the vibration of the piezoelectric vibrator, the vibration deformation function and the equation of volume change are established. Meanwhile, the theoretical equation of the pump flow rate is established. Finally, a real valveless piezoelectric pump with unsymmetrical ridges is manufactured, and the flow rate of the pump is measured through experiments. It is proved that the theory is rational and correct by comparing the experimental flow rate and the theoretical flow rate. In addition, for calculating the theoretical flow rate, the positive and converse flow resistance coefficients of unsymmetrical ridges are measured through experiments, when one slope angle of the unsymmetrical ridges is 90º and another is changing from 20º to 60º, respectively.

关键词： unsymmetrical theoretical flow theoretical equation pump flow converse flow

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Lingguizhugan Decoction, a Chinese herbal formula, improves insulin resistance in overweight/obese subjects

《医学前沿（英文）》 2022年第16卷第5期页码 745-759 doi: 10.1007/s11684-021-0880-3

摘要： Lingguizhugan Decoction (LGZG) has been investigated in basic studies, with satisfactory effects on insulin resistance in non-alcoholic fatty liver disease (NAFLD). This translational approach aimed to explore the effect and underlying mechanism of LGZG in clinical setting. A randomized, double-blinded, placebo-controlled trial was performed. A total of 243 eligible participants with NAFLD were equally allocated to receive LGZG (two groups: standard dose and low dose) or placebo for 12 weeks on the basis of lifestyle modifications. The primary efficacy variable was homeostasis model assessment of insulin resistance (HOMA-IR). Analyses were performed in two populations in accordance with body mass index (BMI; overweight/obese, BMI ≥ 24 kg/m²; lean, BMI < 24 kg/m ²). For overweight/obese participants, low-dose LGZG significantly decreased their HOMA-IR level compared with placebo (−0.19 (1.47) versus 0.08 (1.99),P = 0.038). For lean subjects, neither dose of LGZG showed a superior effect compared with placebo. Methylated DNA immunoprecipitation sequencing and real-time qPCR found that the DNA N6-methyladenine modification levels of protein phosphatase 1 regulatory subunit 3A (PPP1R3A) and autophagy related 3 (ATG3) significantly increased after LGZG intervention in overweight/obese population. Low-dose LGZG effectively improved insulin resistance in overweight/obese subjects with NAFLD. The underlying mechanism may be related to the regulation of DNA N6-methyladenine modification of PPP1R3A and ATG3. Lean subjects may not be a targeted population for LGZG.

关键词： insulin resistance non-alcoholic fatty liver disease Chinese herbal medicine randomized controlled trial DNA N6-methyladenine modification

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Mechanism insight into the formation of HS from thiophene pyrolysis: A theoretical study

《环境科学与工程前沿（英文）》 2021年第15卷第6期 doi: 10.1007/s11783-021-1404-8

摘要：

• Possible formation pathways of H₂S were revealed in thiophene pyrolysis.

关键词： Density functional theory Waste rubber Thiophene H₂S Pyrolysis

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Iteration framework for solving mixed lubrication computation problems

《机械工程前沿（英文）》 2021年第16卷第3期页码 635-648 doi: 10.1007/s11465-021-0632-8

摘要： The general discrete scheme of time-varying Reynolds equation loses the information of the previous step, which makes it unreasonable. A discretization formula of the Reynolds equation, which is based on the Crank–Nicolson method, is proposed considering the physical message of the previous step. Gauss–Seidel relaxation and distribution relaxation are adopted for the linear operators of pressure during the numerical solution procedure. In addition to the convergent criteria of pressure distribution and load, an estimation framework is developed to investigate the relative error of the most important term in the Reynolds equation. Smooth surface with full contacts and mixed elastohydrodynamic lubrication is tested for validation. The asperity contact and sinusoidal wavy surface are examined by the proposed discrete scheme. Results show the precipitous decline in the boundary of the contact area. The relative error suggests that the pressure distribution is reliable and reflects the accuracy and effectiveness of the developed method.

关键词： mixed lubrication discretization formula relative error Reynolds equation asperity

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enhancement in high acidity using di-(2-ethylhexyl)phosphoric acid with [Cl] present: an experimental and theoretical

《化学科学与工程前沿（英文）》 2023年第17卷第1期页码 56-67 doi: 10.1007/s11705-022-2185-8

摘要： Separation of vanadium from black shale leaching solution at low pH is very meaningful, which can effectively avoid the generation of alkali neutralization slag and the resulting vanadium loss. In this study, coordination mechanism of vanadium in acid leaching solution at low pH was investigated with the intervention of chloride ions. Under the conditions of pH 0.8, di-(2-ethylhexyl)phosphoric acid concentration of 20%, phase ratio of 1:2, and extraction time of 8 min, the vanadium extraction could reach 80.00%. The Fourier transform infrared and electrospray ionization results reveal that, despite the fact that the chloride ion in the leachate could significantly promote vanadium extraction, the chloride ion does not enter the organic phase, indicating an intriguing phenomenon. Among Cl⁻–V, SO₄²⁻–V, and H₂O–V, the V–Cl bond is longer and the potential difference between coordinate ions and vanadium is smaller. Therefore, VO²⁺ gets easily desorbed with chloride ions and enter the organic phase. At the same time, the hydrogen ions of di-(2-ethylhexyl)phosphoric acid also enter the water phase more easily, which reduces the pH required for the extraction reaction.

关键词： vanadium black shale solvent extraction high acidity extraction