Search | Engineering

订阅投稿

首页工程期刊工程焦点工程成就工程前沿关于我们 English

资源类型

期刊论文 111

会议信息 1

年份

2023 2

2022 5

2021 10

2020 7

2019 13

2018 10

2017 6

2016 6

2015 10

2014 5

2013 4

2012 9

2011 5

2010 3

2009 3

2008 3

2007 3

2004 3

2001 3

展开︾

关键词

人工智能 2

岩爆 2

机器学习 2

/III-V界面 1

Biological Rhythms 1

Chord图 1

Chronobiology 1

HuMiX 1

Klee图 1

LM331型电压-频率转换器 1

Ni–Ti–Cu–V合金 1

Skyline图 1

Ti-V微合金钢 1

V-W-Mo-Cu催化剂 1

Visual Basic 6.0 1

V形坑 1

academic exchange 1

“五维”拥堵指数 1

三峡工程 1

展开︾

检索范围：

排序：展示方式：

Processing of high-precision ceramic balls with a spiral V-groove plate

Ming FENG,Yongbo WU,Julong YUAN,Zhao PING

《机械工程前沿（英文）》 2017年第12卷第1期页码 132-142 doi: 10.1007/s11465-017-0436-z

摘要：

As the demand for high-performance bearings gradually increases, ceramic balls with excellent properties, such as high accuracy, high reliability, and high chemical durability used, are extensively used for high-performance bearings. In this study, a spiral V-groove plate method is employed in processing high-precision ceramic balls. After the kinematic analysis of the ball-spin angle and enveloped lapping trajectories, an experimental rig is constructed and experiments are conducted to confirm the feasibility of this method. Kinematic analysis results indicate that the method not only allows for the control of the ball-spin angle but also uniformly distributes the enveloped lapping trajectories over the entire ball surface. Experimental results demonstrate that the novel spiral V-groove plate method performs better than the conventional concentric V-groove plate method in terms of roundness, surface roughness, diameter difference, and diameter decrease rate. Ceramic balls with a G3-level accuracy are achieved, and their typical roundness, minimum surface roughness, and diameter difference are 0.05, 0.0045, and 0.105 mm, respectively. These findings confirm that the proposed method can be applied to high-accuracy and high-consistency ceramic ball processing.

关键词： bearing ceramic ball spiral V-groove kinematic analysis trajectory

HTML PDF 收藏

Mathematical model and manufacture programming of loxodromic-type normal circular-arc spiral bevel gear

Zhenyun DUAN, Houjun CHEN, Zhilan JU, Jian LIU

《机械工程前沿（英文）》 2012年第7卷第3期页码 312-321 doi: 10.1007/s11465-012-0308-5

摘要：

In this paper, loxodromic-type normal circular-arc spiral bevel gear is proposed as a novel application of the circular-arc tooth profile at the gear transmission with intersecting axes. Based on the principle of molding-surface conjugation, the study develops a mathematical model for the tooth alignment curve and the computational flow at the design stage to enable the generation of the tooth surface. Machining of the tooth surface is then carried out to determine the interference-free tool path of the numerical control (NC). Moreover, a pair of loxodromic-type normal circular-arc spiral bevel gears is manufactured on computer numerical control (CNC) machine tools. The proposed theory and method are experimentally investigated, and the obtained results primarily reflect the superior performance of the proposed novel gear.

关键词： loxodrome circular-arc tooth profile Wildhaber-Novikov (W-N) gear spiral bevel gear

HTML PDF 收藏

三峡工程水电站压力管道和蜗壳技术结构型式的选择及论证

戴会超,彭澎

《中国工程科学》 2004年第6卷第2期页码 33-37

摘要：

长江三峡水利枢纽工程建设中重大技术问题的决策是建立在大量科学试验和专家论证的基础上，三峡工程水电站压力管道和蜗壳技术结构型式的选择不仅是重大的技术经济问题，也是关系水电站长期运行问题，文章介绍了三峡工程水电站压力管道和蜗壳技术型式选择及决策。

关键词：三峡工程压力管道蜗壳

HTML PDF 收藏

螺旋结构冷却塔的塔板设计方法

黄锐

《中国工程科学》 2008年第10卷第11期页码 43-46

摘要：

针对冷却塔中螺旋结构类型的气液交换塔，提出其内部螺旋塔板形状的设计方法，包括塔壁上外螺旋线和塔中心轴管上内螺旋线的位置确定，以及两线之间螺旋曲面板在平面上的拓扑尺寸。通过塔的几何参数确定螺旋曲面板设计的关键参数，可实现扭曲状塔板与塔壁及内轴的准确配合。

关键词：冷却塔塔板设计螺旋曲面拓扑

HTML PDF 收藏

A wind tunnel study on control methods for cable dry-galloping

Hung D. VO,Hiroshi KATSUCHI,Hitoshi YAMADA,Mayuko NISHIO

《结构与土木工程前沿（英文）》 2016年第10卷第1期页码 72-80 doi: 10.1007/s11709-015-0309-7

摘要： The common vibration of cable caused by rain-wind combination has been known as most typical type and a lot kind of its countermeasures has been proposed for suppressing this phenomenon. Recently, stayed-cables were also proved that they could be excited in dry state (without rain), which is called dry-galloping. Recently, its mechanisms have been explained by axial flow, Reynolds number and so on. To clarify the characteristics of this galloping, wind tunnel test of a cable model with various kinds of wind angle was conducted. Then, three types of countermeasure were examined to suppress dry- galloping of bridge cable. The tests confirmed that the occurrence of dry-galloping depends on relative wind attacked angles and onset reduced wind speed. Furthermore, single spiral wire, double spiral wire and circular ring were found to have high effectiveness in mitigating this galloping when those are installed properly.

关键词： dry-galloping wind-relative angle single spiral wire double spiral wire circular rings

HTML PDF 收藏

弧齿锥齿轮主曲率计算的幺正活动标架法

王裕清,梁剑

《中国工程科学》 2001年第3卷第12期页码 68-70

摘要：

曲面上点的主曲率计算是确定轮齿啮合压痕平面投影形状的关键。文章摈弃通常运用啮合原理和坐标变换计算的思路，从曲面本身的性质出发，把幺正活动标架和外微分引入主曲率计算，得到简明、有效的主曲率计算的新算法，并结合压痕公式给出了一个应用实例。该算法可以推广到任意曲面的主曲率计算。

关键词：弧齿锥齿轮主曲率幺正活动标架

HTML PDF 收藏

圆形金属腔旋流二氧化碳激光器

李再光,龚威

《中国工程科学》 2001年第3卷第1期页码 58-61

摘要：

现有的工业CO₂激光器，主要为横流、纵流和扩散冷却三种。文章提出一种新型激光器，即圆形金属腔CO₂激光器。该激光器的腔体由多个等距、同轴安装的金属腔单元组成。每个腔单元有多个流道，放电在流道与腔体接口处产生，气流将放电及被其激活的粒子吹人腔内，形成增益，输出激光。文章研究了电极结构，金属腔壁对工作气体的冷却作用和腔内的增益分布。研究结果表明：多通道放电吹入和腔内旋流，有利于腔内的均匀放电；金属腔壁有利于腔内对流冷却，降低对气流速度的要求，从而缩小激光器的体积。相邻的腔单元相对转动适当角度，可以提高腔内增益分布的圆周均匀性，从而获得光束质量好的激光束。

关键词：二氧化碳激光器圆形金属腔旋流光束质量

HTML PDF 收藏

An investigation into the heat transfer characteristics of spiral wall with internal rib in a supercritical

TANG Renhu, YIN Fei, WANG Haijun, CHEN Tingkuan

《能源前沿（英文）》 2007年第1卷第3期页码 300-304 doi: 10.1007/s11708-007-0043-5

摘要： Within the pressure range of 9–28 MPa, mass velocity range of 600–1 200 kg/(m · s), and heat flux range of 200–500 kW/m, experiments were performed to investigate the heat transfer to water in the inclined upward internally ribbed tube with an inclined angle of 19.5 degrees, a maximum outer diameter of 38.1 mm, and a thickness of 7.5 mm. Based on the experiments, it was found that heat transfer enhancement of the internally ribbed tube could postpone departure from nucleate boiling at the sub-critical pressure. However, the heat transfer enhancement decreased near the critical pressure. At supercritical pressure, the temperature difference between the wall and the fluid increased near the pseudo-critical temperature, but the increase of wall temperature was less than that of departure from nucleate boiling at sub-critical pressure. When pressure is closer to the critical pressure, the temperature difference between the wall and the fluid increased greatly near the pseudo-critical temperature. Heat transfer to supercritical water in the inclined upward internally ribbed tube was enhanced or deteriorated near the pseudo-critical temperature with the variety of ratio between the mass velocity and the heat flux. Because the rotational flow of the internal groove reduced the effect of natural convection, the internal wall temperature of internally ribbed tube uniformly distributed along the circumference. The maximum internal wall temperature difference of the tube along the circumference was only 10 degrees when the fluid enthalpy exceeded 2 000 J/g. Considering the effect of acute variety of the fluid property on heat transfer, the correlation of heat transfer coefficient on the top of the internally ribbed tube was provided.

关键词： m · diameter critical pressure sub-critical pressure maximum

HTML PDF 收藏

泛曲线齿锥齿轮的创新设计与应用的二次开发

梁桂明

《中国工程科学》 2001年第3卷第7期页码 70-78

摘要：

曲线齿锥齿轮和准双曲面齿轮（统称为“泛曲线齿锥齿轮”），是一种十分复杂而应用越来越广泛的传动装置。在设计上为了避免改变轴交角，而采用"零"变位传动（x₁+x₂=0）设计的齿形制，至今已在各国工业上通用近百年。文章介绍一种"非零"变位传动（x₁+x₂≠0）设计而又保持轴交角不变的创新齿形制。为了满足生产提出的要求，进行了二次开发。经过第二次创新，能在普通锥齿轮加工机床和刀具上切齿，故极易推广。近12年来，已成功地在工程机械、军品、立式机床、机车、船艇、油田、采煤、水泥等机械上采用，取得高综合强度、高可靠性、长寿命、小体积、低噪声、广泛适应性等优点，可取代（或覆盖）全部以美国Gleason为代表的零传动齿制设计的产品，还可实现某些Gleason所达不到的技术要求，故有广泛的应用前景。

关键词：曲线齿锥齿轮创新设计二次开发

HTML PDF 收藏

时域有限差分算法与遗传算法在平面螺旋电感设计中的应用

王宏建,李靖,刘和光,姜景山

《中国工程科学》 2004年第6卷第11期页码 38-42

摘要：

文章通过电磁场时域有限差分(FDTD)算法与遗传算法(GA)相结合进行平面螺旋电感设计。通过优化单元网格大小，可优化设计整个平面螺旋电感（包含空气桥）的结构尺寸。介绍了该方法既能够进行严格的电磁场求解，又可以避免繁杂的实验过程，是优化设计的一种有效而准确的手段。

关键词：时域有限差分算法遗传算法平面螺旋电感品质因素

HTML PDF 收藏

Autoimmunity in acute ischemic stroke and the role of blood—brain barrier: the dark side or the light one?

Nikolay V. Tsygan, Alexandr P. Trashkov, Igor V. Litvinenko, Viktoriya A. Yakovleva, Alexandr V.

《医学前沿（英文）》 2019年第13卷第4期页码 420-426 doi: 10.1007/s11684-019-0688-6

摘要： This article presents a synopsis of the current data on the mechanisms of blood—brain barrier (BBB) alteration and autoimmune response in acute ischemic stroke. Most researchers confirm the relationship between the severity of immunobiochemical changes and clinical outcome of acute ischemic stroke. Ischemic stroke is accompanied by aseptic inflammation, which alters the brain tissue and exposes the co-stimulatory molecules of the immune system and the neuronal antigens. To date, BBB is not considered the border between the immune system and central nervous system, and the local immune subsystems are found within and behind the BBB. BBB disruption contributes to the leakage of brain autoantigens and induction of secondary autoimmune response to neuronal antigens and long-term inflammation. Glymphatic system function is altered and jeopardized both in hemorrhagic and ischemic stroke types. The receptors of innate immunity (toll-like receptor-2 and toll-like receptor-4) are also involved in acute ischemia—reperfusion injury. Immune response is related to the key processes of blood clotting and fibrinolysis. At the same time, the stroke-induced immune activation may promote reparation phenomena in the brain. Subsequent research on the reduction of the acute ischemic brain injury through the target regulation of the immune response is promising.

关键词： stroke blood–brain barrier autoimmunity innate immunity inflammation cell death

HTML PDF 收藏

Emulsification for castor biomass oil

Dongxiang ZHANG, Yuanping LIN, Anmei LI, V. V. TARASOV

《化学科学与工程前沿（英文）》 2011年第5卷第1期页码 96-101 doi: 10.1007/s11705-010-0553-2

摘要： The effect of the emulsifier formula on the stability of castor oil-water system was studied through compounding three groups of emulsifiers from the aspects of stability factor of absorbance, centrifuge stability, demulsification time in quiescence, appearance of the droplets, and viscosity. The best emulsifier formula for castor biomass oil was the composite formula of sorbitan monooleate and polyoxyethylene sorbitan monostearate. Correlation exists between the stability of emulsion and the viscosity/particle size of the droplets, with better stability in the case of greater viscosity or narrower distribution of particle size in the emulsion of castor oil-water system. Methanol added to the castor oil-water system may decrease the viscosity of the emulsion. Comparing the castor oil-water emulsion with methanol-castor oil-water emulsion, the optimal hydrophilic and lipophilic balance (HLB) value based on castor oil-water system was acquired between 6.6 and 7.5, while the optimal HLB value based on the methanol-castor oil-water system was between 5.5 and 6.0. The optimal HLB value of methanol-castor oil-water system gradually moved to that of castor oil-water emulsion with adding more water.

关键词： castor oil biomass oil emulsification stability viscosity corrosivity

HTML PDF 收藏

Synergistic effect of V and Fe in Ni/Fe/V ternary layered double hydroxides for efficient and durable

《化学科学与工程前沿（英文）》 2023年第17卷第1期页码 102-115 doi: 10.1007/s11705-022-2179-6

摘要： High-performance and stable electrocatalysts are vital for the oxygen evolution reaction (OER). Herein, via a one-pot hydrothermal method, Ni/Fe/V ternary layered double hydroxides (NiFeV-LDH) derived from Ni foam are fabricated to work as highly active and durable electrocatalysts for OER. By changing the feeding ratio of Fe and V salts, the prepared ternary hydroxides were optimized. At an Fe:V ratio of 0.5:0.5, NiFeV-LDH exhibits outstanding OER activity superior to that of the binary hydroxides, requiring overpotentials of 269 and 274 mV at 50 mA·cm^–2 in the linear sweep voltammetry and sampled current voltammetry measurements, respectively. Importantly, NiFeV-LDH shows extraordinary long-term stability (≥ 75 h) at an extremely high current density of 200 mA·cm^–2. In contrast, the binary hydroxides present quick decay at 200 mA·cm^–2 or even reduced current densities (150 and 100 mA·cm^–2). The outstanding OER performance of NiFeV-LDH benefits from the synergistic effect of V and Fe while doping the third metal into bimetallic hydroxide layers: (a) Fe plays a crucial role as the active site; (b) electron-withdrawing V stabilizes the high valence state of Fe, thus accelerating the OER process; (c) V further offers great stabilization for the formed intermediate of FeOOH, thus achieving superior durability.

关键词： oxygen evolution reaction electrocatalysts ternary layered double hydroxides long-term stability

HTML PDF 收藏

Association between ICU quality and in-hospital mortality of V-V ECMO-supported patients—the ECMO quality

《医学前沿（英文）》 doi: 10.1007/s11684-023-1014-x

摘要： This cohort study was performed to explore the influence of intensive care unit (ICU) quality on in-hospital mortality of veno-venous (V-V) extracorporeal membrane oxygenation (ECMO)-supported patients in China. The study involved all V-V ECMO-supported patients in 318 of 1700 tertiary hospitals from 2017 to 2019, using data from the National Clinical Improvement System and China National Critical Care Quality Control Center. ICU quality was assessed by quality control indicators and capacity parameters. Among the 2563 V-V ECMO-supported patients in 318 hospitals, a significant correlation was found between ECMO-related complications and prognosis. The reintubation rate within 48 hours after extubation and the total ICU mortality rate were independent risk factors for higher in-hospital mortality of V-V ECMO-supported patients (cutoff: 1.5% and 7.0%; 95% confidence interval: 1.05–1.48 and 1.04–1.45; odds ratios: 1.25 and 1.23; P = 0.012 and P = 0.015, respectively). Meanwhile, the V-V ECMO center volume was a protective factor (cutoff of ≥ 50 cases within the 3-year study period; 95% confidence interval: 0.57–0.83, odds ratio: 0.69, P = 0.0001). The subgroup analysis of 864 patients in 11 high-volume centers further strengthened these findings. Thus, ICU quality may play an important role in improving the prognosis of V-V ECMO-supported patients.

关键词： veno-venous extracorporeal membrane oxygenation in-hospital mortality high-volume centers quality control intensive care unit capacity parameters

HTML PDF 收藏

A concise review about fracture assessments of brittle solids with V-notches

Hsien-Yang YEH, Bin YANG

《结构与土木工程前沿（英文）》 2019年第13卷第2期页码 478-485 doi: 10.1007/s11709-019-0520-z

摘要：

A concise review of recent studies about the fracture assessments of elastic brittle solid materials containing V-notches is presented. In this preliminary and brief survey, elastic stress distributions in V-notched solids are discussed first. The concept of notch stress intensity factor is introduced. Combine the digital image correlation method with numerical computation techniques to analyze the stress distribution near the notches. Fracture criteria such as strain energy density, J-integral, theory of critical distance are used.

关键词： fracture assessment brittle solids V-notches review