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A fast compound direct iterative algorithm for solving transient line contact elastohydrodynamic lubrication problems

Jian LIU,Yuxue CHEN,Zhenzhi HE,Shunian YANG

Frontiers of Mechanical Engineering 2014, Volume 9, Issue 2,   Pages 156-167 doi: 10.1007/s11465-014-0297-7

Abstract: First, by introducing a special matrix splitting iteration method into the traditional compound directiterative method, the full matrices for the linear systems of equations are transformed into sparsebanded ones with any half-bandwidth; then, an extended Thomas method which can solve banded linear systemsalgorithm increases computing speed several times more than the traditional compound direct iterative method

Keywords： elastohydrodynamic lubrication     transient     line contact     matrix splitting iteration method     the Thomas method    

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Functional trait differences between native bunchgrasses and the invasive grass

Huiqin HE, Thomas A. MONACO, Thomas A. JONES

Frontiers of Agricultural Science and Engineering 2018, Volume 5, Issue 1,   Pages 139-147 doi: 10.15302/J-FASE-2017175

Abstract: We conducted 30- and 60-d greenhouse experiments to compare functional traits of (invasive annual grass) and four perennial bunchgrasses under well-watered or drought conditions. Even under drought, experienced significantly less stress (i.e., higher xylem pressure potential and greater shoot water content, water use per day and water-use efficiency) and biomass production than the perennial grasses after 30 d. However, after 60 d, its superiority was reduced under infrequent watering. Differences among perennial grasses were more pronounced for physiological traits under infrequent watering and for morphological traits under frequent watering. (fast-growing species) had a higher transpiration rate, lower leaf temperature, and lower water-use efficiency than the other grasses after 30 d. In contrast, (slow-growing) had lower xylem pressure potential and higher leaf temperature than all other grasses under infrequent watering. Under frequent watering, shoot dry mass and specific leaf area of was matched by (moderate-growing species). Our results indicate that multiple-species plantings or seedings are necessary to foster greater weed resistance against . We also emphasize that when choosing plant material for restoration, performance during both pulse (resource-rich) and inter-pulse (resource-poor) periods should be considered.

Keywords： annual grass     comparative growth     drought response     invasive plant     native grass     specific leaf area     soil-water use    

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Application of cold spraying for flux-free brazing of aluminium alloy 6060

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA,

Frontiers of Mechanical Engineering 2010, Volume 5, Issue 3,   Pages 256-260 doi: 10.1007/s11465-010-0095-9

Abstract: In the present study, samples of aluminium alloy 6060 were coated by cold spraying with a powder of brazing alloy Al12Si. The influence of the process gas temperature on particle velocities and coating build-up was investigated. The coated samples were heat-treated in air and under argon atmosphere to investigate the wetting behaviour of the deposited Al12Si and the diffusion processes between Al12Si coatings and substrates. Coated samples were brazed flux-free under argon atmosphere by an induction heating system. The microstructure of the coated, heat-treated, and brazed samples was investigated. The shear strength of the brazed joints was determined. The results show that the brazing alloy Al12Si could be very well deposited on the substrate by cold spraying. The particle velocity increased with increasing process temperature. Correspondingly, the thickness of Al12Si coatings increased with increasing process temperature. The heat treatments showed that a very good metallurgical bond between the Al12Si coatings and the substrate could be realized by the deposition using cold spraying. The coated samples could be well brazed without fluxes. The coating thickness and overlap width influenced the shear strength of the brazed joints. The highest shear strength of brazed joints amounts to 80 MPa.

Keywords： aluminium alloy     flux-free brazing     cold spraying     shear strength    

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Influence of the filler materials on flux-free brazing of pure aluminium (1050)

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA,

Frontiers of Mechanical Engineering 2010, Volume 5, Issue 1,   Pages 47-51 doi: 10.1007/s11465-009-0079-9

Abstract: In the present study, samples of pure aluminium (1050) were deposited by cold spraying with filler materials such as Al12Si, Al7Si, Al12Si-4%Cu, and the Al-Si-based filler material A, which was especially developed for flux-free brazing by the Surface Engineering Institute. Besides, pure Si powder was also sprayed. The coated samples were heat-treated under different conditions and were brazed under an argon atmosphere without fluxes or with the flux Nokolok by an induction heating system. The shear strength of the brazed joints was determined. The results show that the filler materials could be well deposited by cold spraying. A thin layer of brittle Si could also form due to the strong deformation of the substrate surface. The heat treatments showed that a very good metallurgical bond between the filler materials and the substrate could be realized by the deposition by cold spraying. The Al7Si deposited samples could not be brazed without fluxes under the given conditions. The samples deposited with other filler materials could be brazed without fluxes. The in-situ diffusion process made it possible to braze the Si-deposited samples at 580°C. The joints of the samples deposited with the filler material showed the highest shear strength of 41 MPa, whereas the values of the Al12Si and Si deposited samples were less than 20 MPa. The employment of the flux Nikolok significantly increased the shear strength of the Al12Si deposited samples to more than 53 MPa.

Keywords： aluminium     flux-free brazing     cold spraying     shear strength    

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Development of oxide based diffusion barrier coatings for CFC components applied in modern furnaces

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA

Frontiers of Mechanical Engineering 2011, Volume 6, Issue 4,   Pages 392-396 doi: 10.1007/s11465-011-0241-z

Abstract:

Carbon fibre reinforced carbon (CFC) materials show a high potential for usage in furnaces as sample carriers for example, which is due to their excellent thermal stability compared to steel carriers. Only their tendency to react with different metals at high temperatures by C-diffusion is a disadvantage, which can be solved by application of diffusion barriers. In order to enable the utilization of CFC-carriers for e.g. brazing furnaces, within the frame of this study thermally sprayed diffusion barrier coatings were developed. Coatings of mullite and ZrO2-7%βY2O3 (YSZ) were prepared by air plasma spraying (APS). The coatings were investigated in terms of their microstructure and thermal shock behaviour. In order to prove the suitability of the coatings for the application in brazing furnaces, the wettability of the coating surfaces by a Ni-based brazing alloy was investigated. The results showed that both mullite and YSZ could be deposited on CFC substrates with a bond coat of W or SiC. Both coatings exhibited good thermal shock behaviour and an excellent non-wetting behaviour against the used Ni-based braze alloy.

Keywords： diffusion barrier coatings     carbon fibre reinforced carbon (CFC)     plasma spraying     microstructure     furnace    

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Evaluation of strategies for the subsequent use of CO 2

Marc SCHAEFER, Frank BEHRENDT, Thomas HAMMER,

Frontiers of Chemical Science and Engineering 2010, Volume 4, Issue 2,   Pages 172-183 doi: 10.1007/s11705-009-0236-z

Abstract: If substantial amounts of CO, which according to actual scenarios may in the future be captured from industrial processes and power generation, shall be utilized effectively, scalable energy efficient technologies will be required. Thus, a survey was performed to assess a large variety of applications utilizing CO chemically (e.g., production of synthesis-gas, methanol synthesis), biologically (e.g., CO as fertilizer in green houses, production of algae), or physically (enhancement of fossil fuel recovery, use as refrigerant). For each of the processes, material and energy balances were set up. Starting with pure CO at standard conditions, expenditure for transport and further process specific treatment were included. Based on these calculations, the avoidance of greenhouse gas emissions by applying the discussed technologies was evaluated. Based on the currently available technologies, applications for enhanced fossil fuel recovery turn out to be most attractive regarding the potential of utilizing large quantities of CO (total capacity>1000 Gt CO) and producing significant amounts of marketable products on one hand and having good energy and material balances on the other hand (

Keywords： industrial     generation     production     substantial     enhancement    

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Preparation and characterization of nanocrystalline ZrO2-7%Y2O3 powders for thermal barrier coatings by high-energy ball milling

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA

Frontiers of Mechanical Engineering 2011, Volume 6, Issue 2,   Pages 176-181 doi: 10.1007/s11465-011-0220-4

Abstract:

High-energy ball milling is an effective method to produce nanocrystalline oxides.

Keywords： nanostrucured powders     yttria stabilized zirconia (YSZ)     high-energy ball milling     thermal barrier coatings    

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Editorial for the Special Issue on High-End Measuring Instruments

Jiubin Tan, Kenneth Thomas VictorGrattan

Engineering 2022, Volume 16, Issue 9,   Pages 1-2 doi: 10.1016/j.eng.2022.07.002

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Rhizosphere immunity: targeting the underground for sustainable plant health management

Zhong WEI, Ville-Petri FRIMAN, Thomas POMMIER, Stefan GEISEN, Alexandre JOUSSET, Qirong SHEN

Frontiers of Agricultural Science and Engineering 2020, Volume 7, Issue 3,   Pages 317-328 doi: 10.15302/J-FASE-2020346

Abstract:

Managing plant health is a great challenge for modern food production and is further complicated by the lack of common ground between the many disciplines involved in disease control. Here we present the concept of rhizosphere immunity, in which plant health is considered as an ecosystem level property emerging from networks of interactions between plants, microbiota and the surrounding soil matrix. These interactions can potentially extend the innate plant immune system to a point where the rhizosphere immunity can fulfil all four core functions of a full immune system: pathogen prevention, recognition, response and homeostasis. We suggest that considering plant health from a meta-organism perspective will help in developing multidisciplinary pathogen management strategies that focus on steering the whole plant-microbe-soil networks instead of individual components. This might be achieved by bringing together the latest discoveries in phytopathology, microbiome research, soil science and agronomy to pave the way toward more sustainable and productive agriculture.

Keywords： rhizosphere     soil microbiome     plant immunity     microbial ecology     plant health     soilborne pathogens    

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Thermal response of steel framing members in open car park fires

Xia YAN; Marion CHARLIER; Thomas GERNAY

Frontiers of Structural and Civil Engineering 2022, Volume 16, Issue 9,   Pages 1071-1088 doi: 10.1007/s11709-022-0879-0

Abstract: Regarding the different models, CFD-FEM (CFD: computational fluid dynamics, FEM: finite-element method

Keywords： open car park     localized fire     steel frame     numerical modeling     computational fluid dynamics    

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Scientifically advanced woody media for improved water quality from livestock woodchip heavy-use areas

Laura Christianson, David DeVallance, Joshua Faulkner, Thomas Basden

Frontiers of Environmental Science & Engineering 2017, Volume 11, Issue 3, doi: 10.1007/s11783-017-0909-7

Abstract: Overwintering cattle on pastures in many areas can damage the pasture and lead to impaired water quality. During these times, use of a woodchip heavy-use area (HUA) presents advantages such as a soft, supportive, and dry foot surface for animals and protection of the pasture and pasture soils. However, woodchip HUAs can also be a centralized source of high nutrient loads due to their drainage outflows. A column study was conducted to assess the nutrient load reduction potential of: 1) six types of wood media (including torrefied wood media and biochar) that could be used in a woodchip HUA versus a gravel control, and 2) providing a 48 h retention time within the wood media to enhance nitrogen removal through denitrification. The woody media provided significant liquid waste volume reduction compared to the gravel in simulated events (53%–61% vs. 39% reductions, respectively), and there may be additional liquid storage capacity in the woodchips not utilized during these rapid events. Substantial total nitrogen removal by the wood treatments (mean removal efficiencies>50%) was observed across the simulated events, although nitrate leaching also occurred. Nitrate removal was enhanced during the 48 h retention test which showed removal was governed by availability of labile carbon (i.e., fresh woodchips exhibited>70% nitrate removal). The retention test also indicated biochar mixtures provided some of the best total phosphorus removal, but the greatest benefits across all parameters was provided by the Mixed Hardwood treatment.

Keywords： Overwinter     Heavy-use area     Nutrient pollution     Torrefied     Woodchip    

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Ancient road transport devices: Developments from the Bronze Age to the Roman Empire

Cesare ROSSI,Thomas G. CHONDROS,Kypros F. MILIDONIS,Sergio SAVINO,Flavio RUSSO

Frontiers of Mechanical Engineering 2016, Volume 11, Issue 1,   Pages 12-25 doi: 10.1007/s11465-015-0358-6

Abstract:

The development of transportation systems has significantly enhanced the welfare and modernization of society. Wooden vehicles pulled by animals have been used for land transportation since the early Bronze Age. Whole-body gharries with rigid wheels pulled by oxen appeared in Crete by 2000 BC or earlier. Horses originating from the East were depicted in early Cretan seal-rings of the same period. The two-wheeled horse-drawn chariot was one of the most important inventions in history. This vehicle provided humanity its first concept of personal transport and was the key technology of war for 2000 years. Chariots of Mycenaean and Archaic Greece with light and flexible four-spoked wheels acting as spring suspensions were depicted in vase paintings. The development of this vehicle incorporated the seeds of a primitive design activity and was important for engineering. The Trojan horse since 1194 BC and the helepolis since 700 BC were the first known machines on a wheeled base transported by horses or self-powered. Ancient engineers invented bearings lubricated with fat, and Romans introduced the ancestors of ball bearings for their wagons and carts. The historic evolution of wheeled transportation systems, along with early traction, suspension, and braking systems, is presented in this paper. Analytical and numerical methods are incorporated to analyze the most conceivable loading situations of typically reconstructed wheeled transportation systems in ancient times. Traction requirements both for horse-driven machines and the power for internal motors are also analyzed. This study can serve as a basis for further development of detailed reconstruction of transportation systems in antiquity.

Keywords： transportation     wheel     spoke     cart     axle     bearing    

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International Winter Wheat Improvement Program: history, activities, impact and future

Alexey MORGOUNOV, Fatih OZDEMIR, Mesut KESER, Beyhan AKIN, Thomas PAYNE, Hans-Joachim BRAUN

Frontiers of Agricultural Science and Engineering 2019, Volume 6, Issue 3,   Pages 240-250 doi: 10.15302/J-FASE-2019261

Abstract:

International Winter Wheat Improvement Program (IWWIP) was established in 1986 between the Government of Turkey and CIMMYT with three main objectives: (1) develop winter/facultative germplasm for Central and West Asia, (2) facilitate global winter wheat germplasm exchange, and (3) training wheat scientists. ICARDA joined the program in 1991 making it a three-way partnership that continues to work effectively. The germplasm developed by IWWIP as well as the winter wheat cultivars and lines received from global cooperators are assembled into international nurseries. These nurseries are offered annually to public and private entities (IWWIP website) and distributed to more than 100 cooperators in all continents. IWWIP impact has primarily been in new winter wheat cultivars combining broad adaptation, high yield potential, drought tolerance and disease resistance. A total of 93 IWWIP cultivars have been released in 11 countries occupying annually an estimated 2.5–3.0 Mha. IWWIP cooperation with researchers in Turkey, Central and West Asia and several US universities has resulted in a number of publications reviewed in this paper. Important IWWIP impacts include national inventories of wheat landraces in Turkey, Tajikistan and Uzbekistan, their collection, characterization, evaluation and utilization.

Keywords： biotic and abiotic stresses     breeding     methodology     winter wheat    

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Advances in Molecular Electronics: A Brief Review Review

Paven Thomas Mathew, Fengzhou Fang

Engineering 2018, Volume 4, Issue 6,   Pages 760-771 doi: 10.1016/j.eng.2018.11.001

Abstract:

The field of molecular electronics, also known as moletronics, deals with the assembly of molecular electronic components using molecules as the building blocks. It is an interdisciplinary field that includes physics, chemistry, materials science, and engineering. Moletronics mainly deals with the reduction of size of silicon components. Novel research has been performed in developing electrical-equivalent molecular components. Moletronics has established its influence in electronic and photonic applications, such as conducting polymers, photochromics, organic superconductors, electrochromics, and many more. Since there is a need to reduce the size of the silicon chip, attaining such technology at the molecular level is essential. Although the experimental verification and modeling of molecular devices present a daunting task, vital breakthroughs have been achieved in this field. This article combines an overview of various molecular components, such as molecular transistors, diodes, capacitors, wires, and insulators, with a discussion of the potential applications of different molecules suitable for such components. We emphasize future developments and provide a brief review of different achievements that have been made regarding graphene-based molecular devices.

Keywords： Moletronics     Molecular transistor     Molecular diode     Molecular capacitor     Molecular wire     Graphene    

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Shear design of high strength concrete prestressed girders

DHONDE,Thomas T. C. HSU,Y. L. MO

Frontiers of Structural and Civil Engineering 2014, Volume 8, Issue 4,   Pages 373-387 doi: 10.1007/s11709-014-0087-7

Abstract: The proposed UH-Method was found to accurately predict the ultimate shear strength of PC girders withThe UH-Method was found to be not as overly conservative as the ACI-318 (2011) code provisions, and alsoMoreover, the proposed UH-Method was found fairly accurate and not exceedingly conservative in predicting

Keywords： shear design     high strength concrete     prestressed girders     full-scale tests    

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Title Author Date Type Operation

A fast compound direct iterative algorithm for solving transient line contact elastohydrodynamic lubrication problems

Jian LIU,Yuxue CHEN,Zhenzhi HE,Shunian YANG

Journal Article

Functional trait differences between native bunchgrasses and the invasive grass

Huiqin HE, Thomas A. MONACO, Thomas A. JONES

Journal Article

Application of cold spraying for flux-free brazing of aluminium alloy 6060

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA,

Journal Article

Influence of the filler materials on flux-free brazing of pure aluminium (1050)

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA,

Journal Article

Development of oxide based diffusion barrier coatings for CFC components applied in modern furnaces

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA

Journal Article

Evaluation of strategies for the subsequent use of CO 2

Marc SCHAEFER, Frank BEHRENDT, Thomas HAMMER,

Journal Article

Preparation and characterization of nanocrystalline ZrO2-7%Y2O3 powders for thermal barrier coatings by high-energy ball milling

Kirsten BOBZIN, Lidong ZHAO, Thomas SCHLAEFER, Thomas WARDA

Journal Article

Editorial for the Special Issue on High-End Measuring Instruments

Jiubin Tan, Kenneth Thomas VictorGrattan

Journal Article

Rhizosphere immunity: targeting the underground for sustainable plant health management

Zhong WEI, Ville-Petri FRIMAN, Thomas POMMIER, Stefan GEISEN, Alexandre JOUSSET, Qirong SHEN

Journal Article

Thermal response of steel framing members in open car park fires

Xia YAN; Marion CHARLIER; Thomas GERNAY

Journal Article

Scientifically advanced woody media for improved water quality from livestock woodchip heavy-use areas

Laura Christianson, David DeVallance, Joshua Faulkner, Thomas Basden

Journal Article

Ancient road transport devices: Developments from the Bronze Age to the Roman Empire

Cesare ROSSI,Thomas G. CHONDROS,Kypros F. MILIDONIS,Sergio SAVINO,Flavio RUSSO

Journal Article

International Winter Wheat Improvement Program: history, activities, impact and future

Alexey MORGOUNOV, Fatih OZDEMIR, Mesut KESER, Beyhan AKIN, Thomas PAYNE, Hans-Joachim BRAUN

Journal Article

Advances in Molecular Electronics: A Brief Review

Paven Thomas Mathew, Fengzhou Fang

Journal Article

Shear design of high strength concrete prestressed girders

DHONDE,Thomas T. C. HSU,Y. L. MO

Journal Article