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Validity of Amontons's law for run-in short-cut aramid fiber reinforced elastomers:The effect of epoxy coated fibers

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Friction 2020年第3期8卷 613-625页

作者： m.KHAFIDH D.J.schipper m.A.mASEN N.VLEUGELS W.K.DIERKES J.W.m.NOORDERmEER Faculty of Engineering Technology University of TwenteEnschede 7500AEThe Netherlands Dutch Polymer Institute Eindhoven 5600AXThe Netherlands Department of mechanical Engineering Universitas Islam IndonesiaYogyakarta 55584Indonesia Department of mechanical Engineering Imperial College LondonLondon SW72AZUnited Kingdom

Friction between two contacting surfaces is studied *** of the k n o w n friction theories is Amontons,law which states that the friction force is proportional to the normal ***,Amontons7 law has been found to be invalid for *** the present study,the validity of Amontons7 law for short-cut aramid fiber reinforced elastomers is *** types of fillers are used to reinforce the elastomers,namely highly dispersible silica and short-cut aramid ***-cut aramid fibers with two different surface treatments are used,namely non-reactive fibers with standard oily finish(SF-fibers)and fibers treated with an epoxy coating(EF-fibers).A pin-on-disc tribometer is used to investigate the frictional behavior of the composites in sliding contact with a granite counter *** results show that,after the run-in phase,Amontons,law is valid for those composites that are reinforced by short-cut aramid fibers(without reinforcing filler,i.e.,silica)if the contact pressure is below a threshold ***,once the contact pressure exceeds this threshold value,Amontons'law will be *** threshold contact pressure of the composites containing EF-fibers is higher than of the composites containing *** composites that are reinforced by silica and short-cut aramid fibers do not follow Amontons7 law.

关键词： Amontons's law elastomer epoxy coated fiber short-cut aramid fiber

Is glial heme oxygenase-1 suppression in neurodegenerative disorders permissive for neural repair?

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Neural Regeneration Research 2015年第2期10卷 208-210页

作者： Hyman m. schipper Bloomfield centre for Research in Aging Lady Davis Institute for Medical Research Jewish General Hospital Department of Neurology &Neurosurgery and Department. of Medicine Mc Gill University

＇core＇ neuropathology of degenerative central nervous system （cNS） disorders The common human neurodegenerative disorders （Alzheimer＇s disease （AD）, Parkinson＇s disease （PD）, amyotrophic lateral sclerosis, etc.） vary with respect to risk factors, ages of onset, sex predilections, neuraxial regions affected, hallmark cellular inclusions, behavioral and neurological symptoms, and responses to treatment. Despite these differences, there appears to be a set of ＇core＇ neuropathological features shared among these and related entities. common to these conditions are 1） pathological deposition of non-transferrin bound iron, 2） oxidative stress and associated protein, lipid and nucleic acid modifications, 3） mitochondrial membrane damage and bioenergetic failure, and 4） macroautophagy in the affected neural tissues.

关键词： gene HO Is glial heme oxygenase-1 suppression in neurodegenerative disorders permissive for neural repair GFAP

Hepatosplenic T-cell lymphoma in a 47-year-old crohn's disease patient on thiopurine monotherapy

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World Journal of Gastroenterology 2016年第47期22卷 10465-10470页

作者： maartje m van de meeberg Lauranne AAP Derikx Harm Am Sinnige Peet Nooijen D Lucette schipper Loes Hc Nissen Department of Gastroenterology and Hepatology Jeroen Bosch Hospital Department of Hematology Jeroen Bosch Hospital Department of Pathology Jeroen Bosch Hospital

Hepatosplenic T-cell lymphoma(HSTcL) is a rare nonHodgkin lymphoma with a high mortality rate. Higher incidence is reported in patients with inflammatory bowel disease, specifically in male patients that are younger than 35 years, and have been treated with thiopurine and tumor necrosis factor(TNF)-α inhibitor combination therapy for over 2 years. In this case report we describe a 47-year-old patient with crohn's disease(cD) who developed HSTcL after having been treated with thiopurine monotherapy for 14 years. To our best knowledge, only eleven cases exist of patients with cD who developed HSTcL while on thiopurine monotherapy. We report the first patient with cD, older than 35 years, who developed HSTcL while on thiopurine monotherapy. This emphasizes that HSTcL risk is not limited to young men receiving both thiopurines and TNF-α inhibitors.

关键词： Hepatosplenic T-cell lymphoma Thiopurine crohn’s disease Immunosuppression

Butt-welding Residual Stress of Heat Treatable Aluminum Alloys

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Journal of materials Science & Technology 2007年第2期23卷 217-222页

作者： c.m. cheng Department of Industrial Education National Taiwan Normal University Taipei Taiwan China　

This study, taking three types of aluminum alloys 2024-T351, 6061-T6 and 7075-T6 as experimental materials, conducted single V-groove GTAW （gas tungsten arc welding） butt-welding to analyze and c.m.a.e the magnitude and differences of residual stress in the three aluminum alloys at different single V-groove angles and in restrained or unrestrained conditions. The results show that the larger the grooving angle of butt joint, the higher the residual tensile stress. Too small grooving angle will lead to dramatic differences due to the amount of welding bead filler metal and pre-set joint geometry. Therefore, only an appropriate grooving angle can reduce residual stress. While welding, weldment in restrained condition will lead to a larger residual stress. Also, a residual stress will arise from the restraint position. The ultimate residual stress of weldment is determined by material yield strength at equilibrium temperature. The higher the yield strength at equilibrium temperature, the higher the material residual stress. Because of its larger thermal conductivity, aluminum alloy test specimens have small temperature differential. Therefore, the residual tensile stress of all materials is lower than their yield strength.

关键词： Residual stress Hole-drilling strain-gage method Aluminum alloy Single-V groove

Detection of Breaking Waves Using X-Band Pulse Radar in the Nearshore Region

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china Ocean Engineering 2013年第4期27卷 549-556页

作者： Y.c.Lin c.c.chang m.c.Lee H.c.chan J.m.Leu Department of Hydraulic and Ocean Engineering National Cheng-Kung University Department of Soil and Water conservation National Chung Hsing University Department of Hospitality management Taiwan Shoufu University

An X-band pulsed Doppler microwave radar has been used to determine the characteristics of breaking waves. Field experiments were conducted at the Shuang-Si estuary in the north of Taiwan in the winter of 2005. Analyses on maxima radar cross section and Doppler frequency shift are done to characterize wave breaking zones. Based on observations of breaking waves, the wave breaking zones are shown to be located at water depths of 1.8 to 2.2 m in the experimental site. In general, the results indicate that a radar system has the potential to delineate the spatial variation of breaking waves clearly and that this is sufficient to achieve a measurement operation for near-shore air-sea interaction events.

关键词： radar Doppler effect wave breaking coastal zone

mixing features in an electromagnetic rectangular micromixer for electrolyte solutions

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Journal of Hydrodynamics 2017年第4期29卷 668-678页

作者： m.m.Wen c.N.Kim Department of mechanical Engineering Graduate School Kyung Hee University Department of mechanical Engineering College of Engineering Kyung Hee University

In this study, a new magnetohydrodynamic（mHD） mixer for electrolyte solutions with pumping function is reported, and the mixing performance of the device for two different electrolyte solutions is numerically examined in a uniform magnetic field. Application of different potentials to different electrodes allows the current to be induced. The combination of the induced current and magnetic field yields Lorentz force, resulting in the fluid motion. The numerical simulation for the flows in the device is carried out with commercial software cFX. The validity of cFX code for the present numerical model is presented. The mixing performance of the fluids is investigated in many different cases with different combinations of input voltage of the electrode. This study shows that the mixing performance can be enhanced by applying spatially alternating positive and negative voltages to the electrodes. The present simulation results show that with a magnetic field intensity lower than 0.5 T, a voltage difference smaller than 2.0 V, and an electric conductivity of electrolyte solution of 1.5 S/m the pumping capabilities ranging 1.6×10^（-7）-3.6×10^（-6） kg/s and the mixing indexes higher than 0.90 can be obtained with sophisticated designs of the micromixer.

关键词： mixer electrolyte solution Lorentz force cFX

Hard rock tunnel boring machine penetration test as an indicator of chipping process efficiency

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Journal of Rock mechanics and Geotechnical Engineering 2017年第4期9卷 611-622页

作者： m.c. Villeneuve Department of Geological Sciences University of Canterbury Christchurch 8140 New Zealand

The transition from grinding to chipping can be observed in tunnel boring machine(TBm) penetration test data by plotting the penetration rate(distance/revolution) against the net cutter thrust(force per cutter) over the full range of penetration rates in the *** penetration test data to the geological and geomechanical characteristics of rock masses through which a penetration test is conducted provides the ability to reveal the efficiency of the chipping process in response to changing geological *** test data can also be used to identify stress-induced tunnel face *** research shows that the strength of the rock is an important parameter for controlling how much net cutter thrust is required to transition from grinding to *** also shows that the geological characteristics of a rock will determine how efficient chipping occurs once it has *** particular,geological characteristics that lead to efficient fracture propagation,such as fabric and mica contents,will lead to efficient *** findings will enable a better correlation between TBm performance and geological conditions for use in TBm design,as a basis for contractual payments where penetration rate dominates the excavation cycle and in further academic investigations into the TBm excavation process.

关键词： Penetration rate Grinding chipping Geological characteristics Face stability

Baird’s tapir density in high elevation forests of the Talamanca region of costa Rica

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Integrative Zoology 2012年第4期7卷 381-388页

作者： JoséF.GONZÁLEZ-mAYA Jan schipper Beth POLIDORO Annelie HOEPKER Diego ZÁRRATE-cHARRY Jerrold L.BELANT Sierra to Sea Institute ProCAT Internacional/ColombiaLas AlturasCoto BrusPuntarenasCosta Rica Instituto de Ecología Universidad Nacional Autónoma de México(IE-UNAM)Ciudad UniversitariaDFMexico carnivore Ecology Laboratory Forest and Wildlife Research CenterMississippi State UniversityMississippiUSA Big Island Invasive Species committee University of HawaiiHiloHawaiiUSA Old Dominion University NorfolkVirginiaUSA

Baird’s tapir(Tapirus bairdii)is currently endangered throughout its neotropical range with an expected popula--lished in Valle del Silencio within Parque Internacional La Amistad(PILA).Seventy-seven tapir pictures of 15 individuals comprising 25 capture-recapture events were analyzed using mark-recapture *** 100%minimum convex polygon of the sampled area was 5.7 km2 and the effective sampled area using half mean max-imum distances moved by tapirs was 7.16 *** estimated a tapir density of 2.93 individuals/km2 which rep-resents the highest density reported for this *** valleys can represent unique and important habitats for large mammal ***,the extent of isolation of this population,potentially constrained by steep slopes of the cordillera,remains *** genetic and movement studies are required to un-derstand meta-population dynamics and connectivity between lowland and highland areas for Baird’s tapir con-servation in costa Rica.

关键词： camera trap capture central America populations tapir

Hydrodynamics of the interceptor on a 2-D flat plate by cFD and experiments

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Journal of Hydrodynamics 2015年第6期27卷 919-933页

作者： mANSOORI m. FERNANDES A.c. Department of Naval and Ocean Engineering Federal University of Rio de Janeiro

Nowadays, the use of interceptor by both partial and total dynamic lift crafts is quite common. In this article, a lot of evidence is given regarding the effectiveness of interceptor. The interceptor, when placed at the stern region, changes the pressure distribution around the craft. Its presence affects drag force, lifting force and the position of pressure＇s center leading to a new trim. This study focuses on hydrodynamic effects of interceptors on a 2-D fiat plate based on both computational fluid dynamic （cFD） and experimental approaches. The Reynolds average Navier-Stokes （RANS） equations are used to model the flow around a fixed flat plate with an interceptor at different heights and attack angles. Based on finite volume method and SImPLE algorithm which uses static structures, this model can be analyzed and the RANS results can be c.m.a.ed with the experimental data obtained in the current channel of the laboratory of waves and current of cOPPE/UFRJ （LOc in Portuguese acronym）. According to the results, the increase of pressure at the end of the flat plate was proportional to the interceptor height. In addition, the existence of interceptors can significantly increase the lift force coefficient at high angles of attack also proportional to the interceptor height. The presence of interceptor at the end of the fiat plate increased both the lift coefficient and the drag coefficient but hydrodynamic drag did not grow as fast as the lift coefficient did. The lift coefficient increased much more. Furthermore, the results showed that the interceptor effectiveness is proportional to the boundary layer thickness at the end of the fiat plate. As the interceptor was inside the boundary layer alterations of flow speed led to changes in boundary layer thickness, directly affecting interceptor＇s efficiency. Optimum choice of interceptor height had a great effect on its efficiency, and in choosing it the flow speed and length of the boat must be taken into consideration.

关键词： interceptor craft 2-D fiat plate lifting coefficient Reynolds average Navier-Stokes (RANS) pressure distribution,computational fluid dynamic drag