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friction and plastic deformation to machined surface temperatures and residual stress patterns in finish drycutting

Subhash ANURAG, Yuebin GUO,

《机械工程前沿(英文)》 2010年 第5卷 第3期   页码 247-255 doi: 10.1007/s11465-010-0097-7

摘要: Temperature on the machined surface is critical for surface integrity and the performance of a precision component. However, the temperature of a machined surface is challenging for in-situ measurement. Furthermore, the individual contribution of tool/work friction and plastic deformation of work materials to surface temperature is very difficult to quantify because the measured temperature is always the resultant temperature. This lack of understanding on the temperature distribution blocks the design of effective cutting tool geometries and materials to minimize surface temperature. This study provides a finite element method based on a predictive model to decouple the contributions of tool/work friction and material plastic deformation to surface temperature in a dry cutting process. The study shows that the plastic deformation of work material contributes to the majority of surface temperature, whereas the tool/work friction contribution is secondary. High temperatures are produced when more materials are plowed under the cutting edge. A large tool/work friction leads to higher surface temperatures, and the use of a cutting tool with physical properties in process simulation significantly improves the accuracy of predicted surface temperatures. Residual stress reversal from subsurface maximum residual to surface maximum residual stress may occur when tool/work friction increases.

关键词: surface temperature     friction     residual stress     finite element analysis (FEA)     dry cutting     tool property    

Application of cable-supported spatial grid in dry coal shed

XING Haidong, HAO Jiping, XU Guobin

《结构与土木工程前沿(英文)》 2008年 第2卷 第1期   页码 26-29 doi: 10.1007/s11709-008-0008-8

摘要: This paper presented a new structural style cable-supported spatial grid, which was applied in large span dry coal sheds. The influence of configuration of cable on the force of cable and beam, the ratio of beam force to cable force and the deflection of span was investigated, and a rational configuration of cable was obtained. The results show that the cable-supported spatial grid can maximize the use of material strength, and have the advantages of low usage of steel, large span and sufficient headroom.

关键词: dry     material strength     low     rational configuration     influence    

Influence of HS and NH on biogas dry reforming using Ni catalyst: a study on single and synergetic effect

《环境科学与工程前沿(英文)》 2023年 第17卷 第3期 doi: 10.1007/s11783-023-1632-1

摘要:

● NH3 in biogas had a slight inhibitory effect on dry reforming.

关键词: Biogas     Dry reforming     Sulfur poisoning     Ammonia     Synergetic effect     Hydrogen    

promotes macrophage pyroptosis by driving the glycolytic reprogramming of corneal epithelial cells in dry

《医学前沿(英文)》 2023年 第17卷 第4期   页码 781-795 doi: 10.1007/s11684-023-0986-x

摘要: Tear film hyperosmolarity plays a core role in the development of dry eye disease (DED) by mediating the disruption of ocular surface homeostasis and triggering inflammation in ocular surface epithelium. In this study, the mechanisms involving the hyperosmolar microenvironment, glycolysis mediating metabolic reprogramming, and pyroptosis were explored clinically, in vitro, and in vivo. Data from DED clinical samples indicated that the expression of glycolysis and pyroptosis-related genes, including PKM2 and GSDMD, was significantly upregulated and that the secretion of IL-1β significantly increased. In vitro, the indirect coculture of macrophages derived from THP-1 and human corneal epithelial cells (HCECs) was used to discuss the interaction among cells. The hyperosmolar environment was found to greatly induce HCECs’ metabolic reprogramming, which may be the primary cause of the subsequent inflammation in macrophages upon the activation of the related gene and protein expression. 2-Deoxy-d-glucose (2-DG) could inhibit the glycolysis of HCECs and subsequently suppress the pyroptosis of macrophages. In vivo, 2-DG showed potential efficacy in relieving DED activity and could significantly reduce the overexpression of genes and proteins related to glycolysis and pyroptosis. In summary, our findings suggested that hyperosmolar-induced glycolytic reprogramming played an active role in promoting DED inflammation by mediating pyroptosis.

关键词: dry eye disease     glycolytic reprogramming     pyroptosis     inflammation     2-DG    

Characteristics of pollutants behavior in a stormwater constructed wetland during dry days

Jianghua YU, Kisoo PARK, Youngchul KIM

《环境科学与工程前沿(英文)》 2012年 第6卷 第5期   页码 649-657 doi: 10.1007/s11783-012-0426-7

摘要: A stormwater wetland treating non-point source pollution (NPS) from a 64 ha agricultural watershed was monitored over a period of five months. The results indicated that pH and dissolved oxygen (DO) were increased in the wetland due to the algal growth. The highest total suspended solids (TSS) concentration was observed in the aeration pond due to the resuspension of solids, decreased in the wetland. The respective decreases in total nitrogen (TN) and total kjeldahl nitrogen (TKN) were 15.9% and 28.7% on passing through the wetland. The nitrate and ammonia were increased by 45.4% and decreased by 79.9%, respectively. These variations provided strong evidence for the existence of nitrification. The total phosphorus (TP) and phosphate had respective reductions of 52.3% and 58.2% over the wetland. The total chemical oxygen demand (TCOD) and soluble chemical oxygen demand (SCOD) were also decreased. Generally, the TN, TP and phosphate removal efficiencies were positive. These positive removal efficiencies were mainly due to microbial activities, uptake by plants, and chemical precipitation at high pH. Negative removal efficiencies can be caused by continuous rainfall activities, with short antecedent dry days (ADDs) and unstable hydraulic conditions, some other biogeochemical transformations and algal growth also being important parameters.

关键词: constructed stormwater wetland     dry days     nitrification and denitrification     pollutants characteristic    

Acupuncture for the management of dry eye disease

《医学前沿(英文)》 2022年 第16卷 第6期   页码 975-983 doi: 10.1007/s11684-022-0923-4

摘要: The effectiveness of using acupuncture for dry eye disease (DED) is controversial. Thus, this systematic review investigated the effectiveness and feasibility of using acupuncture for DED in accordance with the 2020 PRISMA statement. The outcomes of interests were (1) to evaluate the efficacy of acupuncture in improving the ocular surface disease index (OSDI), Schirmer I test score, and tear breakup time from baseline to the last follow-up; (2) to determine possible complications of using acupuncture; and (3) to investigate the superiority of acupuncture over other commonly used treatments for DED. Data from 394 patients were collected. Results showed that acupuncture significantly prolonged the tear breakup time (P < 0.0001), significantly increased the Schirmer I test score ( P < 0.0001), and significantly reduced the OSDI ( P < 0.0001) from baseline to the last follow-up. Compared with the control group, the acupuncture group had significantly greater Schirmer I test score ( P < 0.0001), significantly longer tear breakup time ( P = 0.0004), and significantly lower OSDI (P = 0.002). These results suggest that acupuncture is effective and feasible in improving symptoms and signs of DED. No severe adverse effects of acupuncture were observed.

关键词: dry eye disease     xerophthalmus     acupuncture    

Seismic behavior of cantilever wall embedded in dry and saturated sand

Sanku KONAI, Aniruddha SENGUPTA, Kousik DEB

《结构与土木工程前沿(英文)》 2020年 第14卷 第3期   页码 690-705 doi: 10.1007/s11709-020-0615-6

摘要: The embedded cantilever retaining walls are often required for excavation to construct the underground facilities. Significant numbers of numerical and experimental studies have been performed to understand the behavior of embedded cantilever retaining walls under static condition. However, very limited studies have been conducted on the behavior of embedded retaining walls under seismic condition. In this paper, the behavior of a small scale model embedded cantilever retaining wall in dry and saturated sand under seismic loading condition is investigated by shake table tests in the laboratory and numerically using software FLAC2D. The embedded cantilever walls are subjected to sinusoidal dynamic motions. The behaviors of the cantilever walls in terms of lateral displacement and bending moment are studied with the variation of the two important design parameters, peak amplitude of the base motions and excavation depth. The variation of the pore water pressures within the sand is also observed in the cases of saturated sand. The maximum lateral displacement of a cantilever wall due to seismic loading is below 1% of the total height of the wall in dry sand, but in case of saturated sand, it can go up to 12.75% of the total height of the wall.

关键词: embedded cantilever wall     shake table test     FLAC2D     seismic loading     saturated and dry sand    

Use of dry yeast cells as a cheap nitrogen source for lactic acid production by thermophilic

Kim Yng Ooi, Jin Chuan Wu

《化学科学与工程前沿(英文)》 2015年 第9卷 第3期   页码 381-385 doi: 10.1007/s11705-015-1534-2

摘要: Dry yeast cells (DYC) were used as a cheap nitrogen source to replace expensive yeast extract (YE) for L-lactic acid production by thermophilic . Cassava starch (200 g·L ) was converted to L-lactic acid by simultaneous saccharification and fermentation using WCP10-4 at 50 °C in the presence of 20 g·L of DYC, giving 148.1 g·L of L-lactic acid at 27 h with a productivity of 5.5 g·L ·h and a yield of 92%. In contrast, 154.4 g·L of lactic acid was produced at 24 h with a productivity of 6.4 g·L ·h and a yield of 96% when equal amount of YE was used under the same conditions. Use of pre-autolyzed DYC at 50 °C for overnight slightly improved the lactic acid titer (154.5 g·L ) and productivity (7.7 g·L ·h ) but gave the same yield (96%).

关键词: L-lactic acid     thermophilic strain     Bacillus coagulans     dry yeast cells     autolysis     fermentation    

Crystallographic orientation effect on cutting-based single atomic layer removal

Wenkun XIE, Fengzhou FANG

《机械工程前沿(英文)》 2020年 第15卷 第4期   页码 631-644 doi: 10.1007/s11465-020-0599-x

摘要: The ever-increasing requirements for the scalable manufacturing of atomic-scale devices emphasize the significance of developing atomic-scale manufacturing technology. The mechanism of a single atomic layer removal in cutting is the key basic theoretical foundation for atomic-scale mechanical cutting. Material anisotropy is among the key decisive factors that could not be neglected in cutting at such a scale. In the present study, the crystallographic orientation effect on the cutting-based single atomic layer removal of monocrystalline copper is investigated by molecular dynamics simulation. When undeformed chip thickness is in the atomic scale, two kinds of single atomic layer removal mechanisms exist in cutting-based single atomic layer removal, namely, dislocation motion and extrusion, due to the differing atomic structures on different crystallographic planes. On close-packed crystallographic plane, the material removal is dominated by the shear stress-driven dislocation motion, whereas on non-close packed crystallographic planes, extrusion-dominated material removal dominates. To obtain an atomic, defect-free processed surface, the cutting needs to be conducted on the close-packed crystallographic planes of monocrystalline copper.

关键词: ACSM     single atomic layer removal mechanism     crystallographic orientation effect     mechanical cutting     Manufacturing III    

Laboratory study on high-temperature adsorption of HCl by dry-injection of Ca(OH)

Junjun TAN,Guohua YANG,Jingqiao MAO,Huichao DAI

《环境科学与工程前沿(英文)》 2014年 第8卷 第6期   页码 863-870 doi: 10.1007/s11783-013-0618-9

摘要: Combustion-generated hydrogen chloride (HCl) is considered to be a very hazardous acid gaseous pollutant. This paper presents a laboratory study on the dry adsorption of HCl. The experiments were conducted in a dual-layer granular bed filter, at gas temperatures of 500°C–700°C and (Ca)/ (Cl)molar ratios of 1.0–5.0 using the silver nitrate titration method by dry adsorbent powders Ca(OH) . Mainly, the adsorption efficiency of HCl and utilization efficiency of Calcium were studied, by varying relevant factors including (Ca)/ (Cl), temperature, feeding method, water vapor and CO . With a relatively higher HCl concentration of 1000 ppm, the experimental results revealed that 600°C may be the optimum temperature for HCl adsorption when optimum (Ca)/ (Cl) was 2.5 in our tests. The results also demonstrated that the feeding at a constant pressure was more effective, and the HCl adsorption efficiency could rapidly reach over 90% with (Ca)/ (Cl) = 2.5 at 600°C. Furthermore, the HCl adsorption efficiency was found to be slightly promoted by water vapor, while could be impeded by CO , and the utilization efficiency of calcium could be up to 74.4% without CO , while was only 36.8% with CO when (Ca)/ (Cl) was 2.5 at 600°C.

关键词: acid gas HCl     Ca(OH)2     dry adsorption     high temperature     dual-layer granular bed filter    

Modeling of the minimum cutting thickness in micro cutting with consideration of the friction aroundthe cutting zone

Tianfeng ZHOU, Ying WANG, Benshuai RUAN, Zhiqiang LIANG, Xibin WANG

《机械工程前沿(英文)》 2020年 第15卷 第1期   页码 81-88 doi: 10.1007/s11465-019-0561-y

摘要: Friction modeling between the tool and the workpiece plays an important role in predicting the minimum cutting thickness during TC4 micro machining and finite element method (FEM) cutting simulation. In this study, a new three-region friction modeling is proposed to illustrate the material flow mechanism around the friction zone in micro cutting; estimate the stress distributions on the rake, edge, and clearance faces of the tool; and predict the stagnation point location and the minimum cutting thickness. The friction modeling is established by determining the distribution of normal and shear stress. Then, it is applied to calculate the stagnation point location on the edge face and predict the minimum cutting thickness. The stagnation point and the minimum cutting thickness are also observed and illustrated in the FEM simulation. Micro cutting experiments are conducted to validate the accuracy of the friction and the minimum cutting thickness modeling. Comparison results show that the proposed friction model illustrates the relationship between the normal and sheer stress on the tool surface, thereby validating the modeling method of the minimum cutting thickness in micro cutting.

关键词: tool friction     minimum cutting thickness     finite element method     tool edge radius     micro cutting    

A decoupled method to identify affecting mechanism of crosswind on performance of a natural draft dry

Weiliang WANG, Junfu LYU, Hai ZHANG, Qing LIU, Guangxi YUE, Weidou NI

《能源前沿(英文)》 2020年 第14卷 第2期   页码 318-327 doi: 10.1007/s11708-019-0627-x

摘要: The natural draft dry cooling tower (NDDCT) has been increasingly used for cooling in power generation in arid area. As crosswind affects the performance of a NDDCT in a complicated way, and the basic affecting mechanism is unclear, attempts have been made to improve the performance of a NDDCT based on limited experiences. This paper introduces a decoupled method to study the complicated crosswind effects on the inlet and outlet of a NDDCT separately by computational fluid dynamics (CFD) modeling and hot state experiments. Accordingly, the basic affecting mechanism of crosswind on the NDDCT performance is identified. Crosswind changes the inlet flow field of a NDDCT and induces mainstream vortices inside the tower, so as to degrade the ventilation. Besides, low crosswind deflects the upward plume at the outlet to further degrade the ventilation, while high crosswind induces the low pressure area at the outlet to reduce the ventilation degradation.

关键词: affecting mechanism     crosswind     decoupled method     mainstream vortices     natural draft dry cooling tower (NDDCT)     degradation    

A review on ductile mode cutting of brittle materials

Elijah Kwabena ANTWI, Kui LIU, Hao WANG

《机械工程前沿(英文)》 2018年 第13卷 第2期   页码 251-263 doi: 10.1007/s11465-018-0504-z

摘要:

Brittle materials have been widely employed for industrial applications due to their excellent mecha-nical, optical, physical and chemical properties. But obtaining smooth and damage-free surface on brittle materials by traditional machining methods like grinding, lapping and polishing is very costly and extremely time consuming. Ductile mode cutting is a very promising way to achieve high quality and crack-free surfaces of brittle materials. Thus the study of ductile mode cutting of brittle materials has been attracting more and more efforts. This paper provides an overview of ductile mode cutting of brittle materials including ductile nature and plasticity of brittle materials, cutting mechanism, cutting characteristics, molecular dynamic simulation, critical undeformed chip thickness, brittle-ductile transition, subsurface damage, as well as a detailed discussion of ductile mode cutting enhancement. It is believed that ductile mode cutting of brittle materials could be achieved when both crack-free and no subsurface damage are obtained simultaneously.

关键词: ductile mode cutting     brittle materials     critical undeformed chip thickness     brittle-ductile transition     subsurface damage     molecular dynamic simulation    

Cutting performance of surgical electrodes by constructing bionic microstriped structures

《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0728-9

摘要: Surgical electrodes rely on thermal effect of high-frequency current and are a widely used medical tool for cutting and coagulating biological tissue. However, tissue adhesion on the electrode surface and thermal injury to adjacent tissue are serious problems in surgery that can affect cutting performance. A bionic microstriped structure mimicking a banana leaf was constructed on the electrode via nanosecond laser surface texturing, followed by silanization treatment, to enhance lyophobicity. The effect of initial, simple grid-textured, and bionic electrodes with different wettabilities on tissue adhesion and thermal injury were investigated using horizontal and vertical cutting modes. Results showed that the bionic electrode with high lyophobicity can effectively reduce tissue adhesion mass and thermal injury depth/area compared with the initial electrode. The formation mechanism of adhered tissue was discussed in terms of morphological features, and the potential mechanism for antiadhesion and heat dissipation of the bionic electrode was revealed. Furthermore, we evaluated the influence of groove depth on tissue adhesion and thermal injury and then verified the antiadhesion stability of the bionic electrode. This study demonstrates a promising approach for improving the cutting performance of surgical electrodes.

关键词: surgical electrodes     tissue adhesion     thermal injury     bionic structures     cutting performance     medical tools    

Edge preparation methods for cutting tools: a review

《机械工程前沿(英文)》 2023年 第18卷 第4期 doi: 10.1007/s11465-023-0766-y

摘要: Edge preparation can remove cutting edge defects, such as burrs, chippings, and grinding marks, generated in the grinding process and improve the cutting performance and service life of tools. Various edge preparation methods have been proposed for different tool matrix materials, geometries, and application requirements. This study presents a scientific and systematic review of the development of tool edge preparation technology and provides ideas for its future development. First, typical edge characterization methods, which associate the microgeometric characteristics of the cutting edge with cutting performance, are briefly introduced. Then, edge preparation methods for cutting tools, in which materials at the cutting edge area are removed to decrease defects and obtain a suitable microgeometry of the cutting edge for machining, are discussed. New edge preparation methods are explored on the basis of existing processing technologies, and the principles, advantages, and limitations of these methods are systematically summarized and analyzed. Edge preparation methods are classified into two categories: mechanical processing methods and nontraditional processing methods. These methods are compared from the aspects of edge consistency, surface quality, efficiency, processing difficulty, machining cost, and general availability. In this manner, a more intuitive understanding of the characteristics can be gained. Finally, the future development direction of tool edge preparation technology is prospected.

关键词: edge preparation method     preparation principle     cutting edge geometry     edge characterization     tool performance    

标题 作者 时间 类型 操作

friction and plastic deformation to machined surface temperatures and residual stress patterns in finish drycutting

Subhash ANURAG, Yuebin GUO,

期刊论文

Application of cable-supported spatial grid in dry coal shed

XING Haidong, HAO Jiping, XU Guobin

期刊论文

Influence of HS and NH on biogas dry reforming using Ni catalyst: a study on single and synergetic effect

期刊论文

promotes macrophage pyroptosis by driving the glycolytic reprogramming of corneal epithelial cells in dry

期刊论文

Characteristics of pollutants behavior in a stormwater constructed wetland during dry days

Jianghua YU, Kisoo PARK, Youngchul KIM

期刊论文

Acupuncture for the management of dry eye disease

期刊论文

Seismic behavior of cantilever wall embedded in dry and saturated sand

Sanku KONAI, Aniruddha SENGUPTA, Kousik DEB

期刊论文

Use of dry yeast cells as a cheap nitrogen source for lactic acid production by thermophilic

Kim Yng Ooi, Jin Chuan Wu

期刊论文

Crystallographic orientation effect on cutting-based single atomic layer removal

Wenkun XIE, Fengzhou FANG

期刊论文

Laboratory study on high-temperature adsorption of HCl by dry-injection of Ca(OH)

Junjun TAN,Guohua YANG,Jingqiao MAO,Huichao DAI

期刊论文

Modeling of the minimum cutting thickness in micro cutting with consideration of the friction aroundthe cutting zone

Tianfeng ZHOU, Ying WANG, Benshuai RUAN, Zhiqiang LIANG, Xibin WANG

期刊论文

A decoupled method to identify affecting mechanism of crosswind on performance of a natural draft dry

Weiliang WANG, Junfu LYU, Hai ZHANG, Qing LIU, Guangxi YUE, Weidou NI

期刊论文

A review on ductile mode cutting of brittle materials

Elijah Kwabena ANTWI, Kui LIU, Hao WANG

期刊论文

Cutting performance of surgical electrodes by constructing bionic microstriped structures

期刊论文

Edge preparation methods for cutting tools: a review

期刊论文