The reach of tribology has expanded in diverse fields and tribology related research activities have seen immense growth during the last decade.This review takes stock of the recent advances in research pertaining to ...The reach of tribology has expanded in diverse fields and tribology related research activities have seen immense growth during the last decade.This review takes stock of the recent advances in research pertaining to different aspects of tribology within the last 2 to 3 years.Different aspects of tribology that have been reviewed including lubrication,wear and surface engineering,biotribology,high tem perature tribology,and computational tribology.This review attempts to highlight recent research and also presents future outlook pertaining to these aspects.It may however be noted that there are limitations of this review.One of the most important of these is that tribology being a highly multidisciplinary field,the research results are widely spread across various disciplines and there can be omissions because of this.Secondly,the topics dealt with in the field of tribology include only some of the salient topics(such as lubrication,wear,surface engineering,biotribology,high tem perature tribology,and computational tribology)but there are many more aspects of tribology that have not been covered in this review.Despite these limitations it is hoped that such a review will bring the most recent salient research in focus and will be beneficial for the growing community of tribology researchers.展开更多
In response to the need in industry for a quick and reproducible method of measuring the flowability of powders in processes involving transport and storage, the apparently simple idea of measuring angle of repose has...In response to the need in industry for a quick and reproducible method of measuring the flowability of powders in processes involving transport and storage, the apparently simple idea of measuring angle of repose has been revived. The simple tester first used has evolved over a number of years into the present version which is shown to be capable of handling quite small samples of powders that are even slightly cohesive. Experimental data are presented and results shown to compare consistently with the better known Hausner ratio.展开更多
BACKGROUND： Laparoscopic pancreaticoduodenectomy（LPD）is a safe procedure. Oncological safety of LPD is still a matter for debate. This study aimed to compare the oncological outcomes,in terms of adequacy of resecti...BACKGROUND： Laparoscopic pancreaticoduodenectomy（LPD）is a safe procedure. Oncological safety of LPD is still a matter for debate. This study aimed to compare the oncological outcomes,in terms of adequacy of resection and recurrence rate following LPD and open pancreaticoduodenectomy（OPD）.METHODS： Between November 2005 and April 2009, 12LPDs（9 ampullary and 3 distal common bile duct tumors）were performed. A cohort of 12 OPDs were matched for age,gender, body mass index（BMI） and American Society of Anesthesiologists（ASA） score and tumor site.RESULTS： Mean tumor size LPD vs OPD（19.8 vs 19.2 mm,P=0.870）. R0 resection was achieved in 9 LPD vs 8 OPD（P=1.000）. The mean number of metastatic lymph nodes and total number resected for LPD vs OPD were 1.1 vs 2.1（P=0.140）and 20.7 vs 18.5（P=0.534） respectively. Clavien complications grade I/II（5 vs 8）, III/IV（2 vs 6） and pancreatic leak（2 vs 1）were statistically not significant（LPD vs OPD）. The mean high dependency unit（HDU） stay was longer in OPD（3.7 vs 1.4 days,P〈0.001）. There were 2 recurrences each in LPD and OPD（logrank,P=0.983）. Overall mortality for LPD vs OPD was 3 vs 6（log-rank, P=0.283） and recurrence-related mortality was 2 vs 1.There was one death within 30 days in the OPD group secondary to severe sepsis and none in the LPD group.CONCLUSIONS： Compared to open procedure, LPD achieved a similar rate of R0 resection, lymph node harvest and longterm recurrence for tumors less than 2 cm. Though technically challenging, LPD is safe and does not compromise oncological outcome.展开更多
The use of X-ray microtomographic （XMT） methods in analysing particulate systems has expanded rapidly in recent years with the availability of affordable desk-top apparatus. This review presents a summary of the maj...The use of X-ray microtomographic （XMT） methods in analysing particulate systems has expanded rapidly in recent years with the availability of affordable desk-top apparatus. This review presents a summary of the major applications in which computer simulations are explicitly coupled with XMT in the area of granular and porous materials. We envisage two main ways of establishing the coupling between both techniques, based on the transference or exchange of information by using physical or geometrical parameters （i.e. a parametric link through fitting to a process model） or through the direct use of3D XMT digital images （i.e. comparing image pixels and features directly）. Examples of coupled applications are shown for the study of transport properties of rocks, particle packing, mechanical loading and sintering. Often, the link between XMT and computer simulations is based on visual comparisons and we conclude that the use of quantitative parameters such as the number of interparticle contacts, force networks or granule shape to link both techniques is still underrepresented in the literature. Strategies to provide a more robust and quantitative approach to optimise the information obtained from such tomography analyses are proposed. 2010 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.展开更多
The widespread microbialites deposition that followed the End-Permian mass extinction in the Tethyan realm have been intensively studied because of the evidence they provide on the nature of this crisis and its afterm...The widespread microbialites deposition that followed the End-Permian mass extinction in the Tethyan realm have been intensively studied because of the evidence they provide on the nature of this crisis and its aftermath. However, the age of the microbialite event remains controversial. New conodont collection across the Permian–Triassic（P–T） transition from Dajiang（Guizhou Province, South China） in this study enable us to discriminate four conodont zones, in ascending order, they are： Hindeodus parvus zone, Isarcicella lobata zone, Isarcicella isarcica zone and Hindeodus sosioensis zone. The age of microbialite in the P–T transition at the Dajiang Section is considered to be within the Hindeodus parvus zone and thus to clearly post-date the main extinction crisis. Reviewing the age of onset of microbialites throughout the Tethyan regions reveals two different ages： a Hindeodus changxingensis zone age is dominant in south-western and westernmost Tethys, whilst most other regions show microbialite deposition began in the Hindeodus parvus zone. Our investigation also indicates that two conodont changes occur at this time： an increase of hindeodid species immediately following a sequence boundary and the mass extinction, and a phase of extinction losses in the earliest Triassic Isarcicella isarcica zone during highstand development.展开更多
Both linear-spring-dashpot （LSD） and non-linear Hertzian-spring-dashpot （HSD） contact models are commonly used for the calculation of contact forces in Discrete Element Method （DEM） simulations of granular syste...Both linear-spring-dashpot （LSD） and non-linear Hertzian-spring-dashpot （HSD） contact models are commonly used for the calculation of contact forces in Discrete Element Method （DEM） simulations of granular systems. Despite the popularity of these models, determination of suitable values for the contact parameters of the simulated particles such as stiffness, damping coefficient, coefficient of restitution, and simulation time step, is not altogether obvious. In this work the relationships between these contact parameters for a model system where a particle impacts on a flat base are examined. Recommendations are made concerning the determination of these contact parameters for use in DEM simulations.展开更多
This paper discusses composite materials based on inorganic salts for medium- and high-temperature thermal energy storage application. The composites consist of a phase change material （PCM）, a ceramic material, and...This paper discusses composite materials based on inorganic salts for medium- and high-temperature thermal energy storage application. The composites consist of a phase change material （PCM）, a ceramic material, and a high thermal conductivity material. The ceramic material forms a microstructural skeleton for encapsulation of the PCM and structural stability of the composites; the high thermal conductivity material enhances the overall thermal conductivity of the composites. Using a eutectic salt of lithium and sodium carbonates as the PCM, magnesium oxide as the ceramic skeleton, and either graphite flakes or carbon nanotubes as the thermal conductivity enhancer, we produced composites with good physical and chemical stability and high thermal conductivity. We found that the wettability of the molten salt on the ceramic and carbon materials significantly affects the microstructure of the composites.展开更多
The prevalence of type 2 diabetes(T2D)has increased worldwide and doubled over the last two decades.It features among the top 10 causes of mortality and morbidity in the world.Cardiovascular disease is the leading cau...The prevalence of type 2 diabetes(T2D)has increased worldwide and doubled over the last two decades.It features among the top 10 causes of mortality and morbidity in the world.Cardiovascular disease is the leading cause of complications in diabetes and within this,heart failure has been shown to be the leading cause of emergency admissions in the United Kingdom.There are many hypotheses and well-evidenced mechanisms by which diabetic cardiomyopathy as an entity develops.This review aims to give an overview of these mechanisms,with particular emphasis on metabolic inflexibility.T2D is associated with inefficient substrate utilisation,an inability to increase glucose metabolism and dependence on fatty acid oxidation within the diabetic heart resulting in mitochondrial uncoupling,glucotoxicity,lipotoxicity and initially subclinical cardiac dysfunction and finally in overt heart failure.The review also gives a concise update on developments within clinical imaging,specifically cardiac magnetic resonance studies to characterise and phenotype early cardiac dysfunction in T2D.A better understanding of the pathophysiology involved provides a platform for targeted therapy in diabetes to prevent the development of early heart failure with preserved ejection fraction.展开更多
The recent review for the Restriction of Hazardous Substances Directive(RoHS)by the expert committee,appointed by the European Union,stated that the replacement of PZT“…may be scientifically and technologically prac...The recent review for the Restriction of Hazardous Substances Directive(RoHS)by the expert committee,appointed by the European Union,stated that the replacement of PZT“…may be scientifically and technologically practical to a certain degree…”,although replacement“…is scientifically and technically still impractical in the majority of applications.”Thus,two decades of sustained research and development may be approaching fruition,at first limited to a minority of applications.Therefore,it is of paramount importance to assess the viability of lead-free piezoceramics over a broad range of application-relevant properties.These are identified and discussed in turn:1.Cost,2.Reproducibility,3.Mechanical and Thermal Properties,4.Electrical Conductivity,and 5.Lifetime.It is suggested that the worldwide efforts into the development of lead-free piezoceramics now require a broader perspective to bring the work to the next stage of development by supporting implementation into real devices.Guidelines about pertinent research requirements into a wide range of secondary properties,measurement techniques,and salient literature are provided.展开更多
Studying and understanding of the surface topography variation are the basis for analyzing tribological problems,and characterization of worn surface is necessary.Fractal geometry offers a more accurate description fo...Studying and understanding of the surface topography variation are the basis for analyzing tribological problems,and characterization of worn surface is necessary.Fractal geometry offers a more accurate description for surface roughness that topographic surfaces are statistically self-similar and can be quantitatively evaluated by fractal parameters.The change regularity of worn surface topography is one of the most important aspects of running-in study.However,the existing research normally adopts only one friction matching pair to explore the surface topography change,which interrupts the running-in wear process and makes the experimental result lack authenticity and objectivity.In this paper,to investigate the change regularity of surface topography during the real running-in process,a series of running-in tests by changing friction pairs under the same operating conditions are conducted on UMT-II Universal Multifunction Tester.The surface profile data are acquired by MiaoXAM2.5X-50X Ultrahigh Precision Surface 3D Profiler and analyzed using fractal dimension D,scale coefficient C and characteristic roughness Ra ＊based on root mean square（RMS） method.The characterization effects of the three parameters are discussed and compared.The results obtained show that there exists remarkable fractal feature of surface topography during running-in process,both D and Ra ＊increase gradually,while C decreases slowly as the wear-in process goes on,and all parameters tend to be stable when the wear process steps into the normal wear process.Ra ＊illustrates higher sensitivity for rough surface characterization compared with the other two parameters.In addition,the running-in test carried with a set of identical surface properties is more scientific and reasonable than the traditional one.The proposed research further indicates that the fractal method can quantitatively measure the rough surface,which also provides an evidence for running-in process identification and tribology design.展开更多
Lung cancer is the most common cause of death from cancer in males,accounting for more than 1.4 million deaths in 2008.It is a growing concern in China,Asia and Africa as well.Accurate staging of the disease is an im... Lung cancer is the most common cause of death from cancer in males,accounting for more than 1.4 million deaths in 2008.It is a growing concern in China,Asia and Africa as well.Accurate staging of the disease is an important part of the management as it provides estimation of patient’s prognosis and identifies treatment sterategies.It also helps to build a database for future staging projects.A major revision of lung cancer staging has been announced with effect from January 2010.The new classification is based on a larger surgical and non-surgical cohort of patients,and thus more accurate in terms of outcome prediction compared to the previous classification.There are several original papers regarding this new classification which give comprehensive description of the methodology,the changes in the staging and the statistical analysis.This overview is a simplified description of the changes in the new classification and their potential impact on patients’ treatment and prognosis.展开更多
Tectonic movements formed several unconfor- mities in the north-west margin of the Junggar basin. Based on data of outcrop, core, and samples, the unconformity is a structural body whose formation associates with weat...Tectonic movements formed several unconfor- mities in the north-west margin of the Junggar basin. Based on data of outcrop, core, and samples, the unconformity is a structural body whose formation associates with weath- ering, leaching, and onlap. At the same time, the structural body may be divided into three layers, including upper layer, mid layer, and lower layer. The upper layer with good primary porosity serves as the hydrocarbon migration system, and also accumulates the hydrocarbon. The mid layer with compactness and ductility can play a role as cap rock, the strength of which increases with depth. The lower layer with good secondary porosity due to weathering and leaching can form the stratigraphic truncation traps. A typical stratigraphie reservoir lying in the unconformity between the Jurassic and Triassic in the north-west margin of the Junggar basin was meticulously analyzed in order to reveal the key controlling factors. The results showed that the hydrocarbon distribution in the stratigraphic onlap reservoirs was controlled by the onlap line, the hydro- carbon distribution in the stratigraphic truncation reser- voirs was confined by the truncation line, and the mid layer acted as the key sealing rock. So a conclusion was drawn that ＂two lines （onlap line and truncation line） and a body （unconformity structural body）＂ control the formation and distribution of stratigraphic reservoirs.展开更多
Na2CO3/MgO composites with added multi-walled carbon nanotubes （MWCNTs） were prepared and tested as phase change materials （PCMs） for thermal energy storage. Na2CO3/MgO composite PCMs were prepared and their chemi...Na2CO3/MgO composites with added multi-walled carbon nanotubes （MWCNTs） were prepared and tested as phase change materials （PCMs） for thermal energy storage. Na2CO3/MgO composite PCMs were prepared and their chemical compatibility and thermal stability were studied. MWCNTs introduced with Na2CO3/MgO composite PCMs were also investigated and scanning electron microscopy （SEM） characterization was used to demonstrate the uniform dispersion of MWCNTs in Na2CO3/MgO composite PCMs. The composites with added MWCNTs still display good thermal stability with mass losses lower than 5%. Introducing MWCNTs into composite Na2CO3/MgO PCMs by material formation/calcination signifi.cantly enhances the thermal conductivity of the composite PCMs. The thermal conductivity of the composite PCMs was found to increase with an increase in the weight fraction of the added MWCNTs and an increase in the testing temperature. This study may present a promising way to prepare high temperature phase change materials with superior properties such as improved thermal stability.展开更多
This short communication reports our recent work on the synthesis and characterisation ofmicrocapsules of phase change materials using silica as the shell material through a one-step method. The method uses no surfact...This short communication reports our recent work on the synthesis and characterisation ofmicrocapsules of phase change materials using silica as the shell material through a one-step method. The method uses no surfactants or dispersants for stabilising the capsules. The results show that the one-step method allows the tuning of the size and polydispersity of the capsules, and the use of different core materials. Analyses of the capsules show that they contain about 65% phase change materials. The results also suggest no need for a stabilising agent due to self-stabilisation by the amine groups. Further work is underway to investigate the mechanical and thermal properties of the microcapsules and the scale-up of the method.展开更多
基金National N atural Science Foundation of China(Grant Nos.51635009 and 51775460)the funding of State Key Laboratory of Tribology,China(SKLT2018C05).
文摘The reach of tribology has expanded in diverse fields and tribology related research activities have seen immense growth during the last decade.This review takes stock of the recent advances in research pertaining to different aspects of tribology within the last 2 to 3 years.Different aspects of tribology that have been reviewed including lubrication,wear and surface engineering,biotribology,high tem perature tribology,and computational tribology.This review attempts to highlight recent research and also presents future outlook pertaining to these aspects.It may however be noted that there are limitations of this review.One of the most important of these is that tribology being a highly multidisciplinary field,the research results are widely spread across various disciplines and there can be omissions because of this.Secondly,the topics dealt with in the field of tribology include only some of the salient topics(such as lubrication,wear,surface engineering,biotribology,high tem perature tribology,and computational tribology)but there are many more aspects of tribology that have not been covered in this review.Despite these limitations it is hoped that such a review will bring the most recent salient research in focus and will be beneficial for the growing community of tribology researchers.
文摘In response to the need in industry for a quick and reproducible method of measuring the flowability of powders in processes involving transport and storage, the apparently simple idea of measuring angle of repose has been revived. The simple tester first used has evolved over a number of years into the present version which is shown to be capable of handling quite small samples of powders that are even slightly cohesive. Experimental data are presented and results shown to compare consistently with the better known Hausner ratio.
文摘BACKGROUND： Laparoscopic pancreaticoduodenectomy（LPD）is a safe procedure. Oncological safety of LPD is still a matter for debate. This study aimed to compare the oncological outcomes,in terms of adequacy of resection and recurrence rate following LPD and open pancreaticoduodenectomy（OPD）.METHODS： Between November 2005 and April 2009, 12LPDs（9 ampullary and 3 distal common bile duct tumors）were performed. A cohort of 12 OPDs were matched for age,gender, body mass index（BMI） and American Society of Anesthesiologists（ASA） score and tumor site.RESULTS： Mean tumor size LPD vs OPD（19.8 vs 19.2 mm,P=0.870）. R0 resection was achieved in 9 LPD vs 8 OPD（P=1.000）. The mean number of metastatic lymph nodes and total number resected for LPD vs OPD were 1.1 vs 2.1（P=0.140）and 20.7 vs 18.5（P=0.534） respectively. Clavien complications grade I/II（5 vs 8）, III/IV（2 vs 6） and pancreatic leak（2 vs 1）were statistically not significant（LPD vs OPD）. The mean high dependency unit（HDU） stay was longer in OPD（3.7 vs 1.4 days,P〈0.001）. There were 2 recurrences each in LPD and OPD（logrank,P=0.983）. Overall mortality for LPD vs OPD was 3 vs 6（log-rank, P=0.283） and recurrence-related mortality was 2 vs 1.There was one death within 30 days in the OPD group secondary to severe sepsis and none in the LPD group.CONCLUSIONS： Compared to open procedure, LPD achieved a similar rate of R0 resection, lymph node harvest and longterm recurrence for tumors less than 2 cm. Though technically challenging, LPD is safe and does not compromise oncological outcome.
基金support of this work (Grant EP/D031257/1)and the contribution of illustrations from Prof. U. Tuzun (University of Surrey), Prof. C. Lin(University of Utah) and Dr C. Selomulya (Monash University)
文摘The use of X-ray microtomographic （XMT） methods in analysing particulate systems has expanded rapidly in recent years with the availability of affordable desk-top apparatus. This review presents a summary of the major applications in which computer simulations are explicitly coupled with XMT in the area of granular and porous materials. We envisage two main ways of establishing the coupling between both techniques, based on the transference or exchange of information by using physical or geometrical parameters （i.e. a parametric link through fitting to a process model） or through the direct use of3D XMT digital images （i.e. comparing image pixels and features directly）. Examples of coupled applications are shown for the study of transport properties of rocks, particle packing, mechanical loading and sintering. Often, the link between XMT and computer simulations is based on visual comparisons and we conclude that the use of quantitative parameters such as the number of interparticle contacts, force networks or granule shape to link both techniques is still underrepresented in the literature. Strategies to provide a more robust and quantitative approach to optimise the information obtained from such tomography analyses are proposed. 2010 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.
基金supported by the Natural Science Foundation of China (Nos. 41172024, 41272044)the "973" Program (No. 2011CB808800)+2 种基金the "111" Project (No. B08030)the ‘Fundamental Research Funds for the Central Universities,China University of Geosciences (Wuhan)the State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (No. GBL11202)
文摘The widespread microbialites deposition that followed the End-Permian mass extinction in the Tethyan realm have been intensively studied because of the evidence they provide on the nature of this crisis and its aftermath. However, the age of the microbialite event remains controversial. New conodont collection across the Permian–Triassic（P–T） transition from Dajiang（Guizhou Province, South China） in this study enable us to discriminate four conodont zones, in ascending order, they are： Hindeodus parvus zone, Isarcicella lobata zone, Isarcicella isarcica zone and Hindeodus sosioensis zone. The age of microbialite in the P–T transition at the Dajiang Section is considered to be within the Hindeodus parvus zone and thus to clearly post-date the main extinction crisis. Reviewing the age of onset of microbialites throughout the Tethyan regions reveals two different ages： a Hindeodus changxingensis zone age is dominant in south-western and westernmost Tethys, whilst most other regions show microbialite deposition began in the Hindeodus parvus zone. Our investigation also indicates that two conodont changes occur at this time： an increase of hindeodid species immediately following a sequence boundary and the mass extinction, and a phase of extinction losses in the earliest Triassic Isarcicella isarcica zone during highstand development.
基金support to Mr Malone in the form of CASE studentship [GR/P03711/01].
文摘Both linear-spring-dashpot （LSD） and non-linear Hertzian-spring-dashpot （HSD） contact models are commonly used for the calculation of contact forces in Discrete Element Method （DEM） simulations of granular systems. Despite the popularity of these models, determination of suitable values for the contact parameters of the simulated particles such as stiffness, damping coefficient, coefficient of restitution, and simulation time step, is not altogether obvious. In this work the relationships between these contact parameters for a model system where a particle impacts on a flat base are examined. Recommendations are made concerning the determination of these contact parameters for use in DEM simulations.
基金supported by the Focused Deployment Project of the Chinese Academy of Sciences(KGZD-EW-302-1)Key Technologies R&D Program of China(No.2012BAA03B03)+1 种基金Natural Science Foundation of China(Grant No.21106151)the UK Engineering and Physical Sciences Research Council(EPSRC)under grant EP/K002252/1
文摘This paper discusses composite materials based on inorganic salts for medium- and high-temperature thermal energy storage application. The composites consist of a phase change material （PCM）, a ceramic material, and a high thermal conductivity material. The ceramic material forms a microstructural skeleton for encapsulation of the PCM and structural stability of the composites; the high thermal conductivity material enhances the overall thermal conductivity of the composites. Using a eutectic salt of lithium and sodium carbonates as the PCM, magnesium oxide as the ceramic skeleton, and either graphite flakes or carbon nanotubes as the thermal conductivity enhancer, we produced composites with good physical and chemical stability and high thermal conductivity. We found that the wettability of the molten salt on the ceramic and carbon materials significantly affects the microstructure of the composites.
文摘The prevalence of type 2 diabetes(T2D)has increased worldwide and doubled over the last two decades.It features among the top 10 causes of mortality and morbidity in the world.Cardiovascular disease is the leading cause of complications in diabetes and within this,heart failure has been shown to be the leading cause of emergency admissions in the United Kingdom.There are many hypotheses and well-evidenced mechanisms by which diabetic cardiomyopathy as an entity develops.This review aims to give an overview of these mechanisms,with particular emphasis on metabolic inflexibility.T2D is associated with inefficient substrate utilisation,an inability to increase glucose metabolism and dependence on fatty acid oxidation within the diabetic heart resulting in mitochondrial uncoupling,glucotoxicity,lipotoxicity and initially subclinical cardiac dysfunction and finally in overt heart failure.The review also gives a concise update on developments within clinical imaging,specifically cardiac magnetic resonance studies to characterise and phenotype early cardiac dysfunction in T2D.A better understanding of the pathophysiology involved provides a platform for targeted therapy in diabetes to prevent the development of early heart failure with preserved ejection fraction.
文摘The recent review for the Restriction of Hazardous Substances Directive(RoHS)by the expert committee,appointed by the European Union,stated that the replacement of PZT“…may be scientifically and technologically practical to a certain degree…”,although replacement“…is scientifically and technically still impractical in the majority of applications.”Thus,two decades of sustained research and development may be approaching fruition,at first limited to a minority of applications.Therefore,it is of paramount importance to assess the viability of lead-free piezoceramics over a broad range of application-relevant properties.These are identified and discussed in turn:1.Cost,2.Reproducibility,3.Mechanical and Thermal Properties,4.Electrical Conductivity,and 5.Lifetime.It is suggested that the worldwide efforts into the development of lead-free piezoceramics now require a broader perspective to bring the work to the next stage of development by supporting implementation into real devices.Guidelines about pertinent research requirements into a wide range of secondary properties,measurement techniques,and salient literature are provided.
基金supported by National Natural Science Foundation of China (Grant No.50975276,Grant No.50475164)National Basic Research Program of China (973 Program,Grant No.2007CB607605)Doctoral Programs Foundation of Ministry of Education of China (Grant No.200802900513)
文摘Studying and understanding of the surface topography variation are the basis for analyzing tribological problems,and characterization of worn surface is necessary.Fractal geometry offers a more accurate description for surface roughness that topographic surfaces are statistically self-similar and can be quantitatively evaluated by fractal parameters.The change regularity of worn surface topography is one of the most important aspects of running-in study.However,the existing research normally adopts only one friction matching pair to explore the surface topography change,which interrupts the running-in wear process and makes the experimental result lack authenticity and objectivity.In this paper,to investigate the change regularity of surface topography during the real running-in process,a series of running-in tests by changing friction pairs under the same operating conditions are conducted on UMT-II Universal Multifunction Tester.The surface profile data are acquired by MiaoXAM2.5X-50X Ultrahigh Precision Surface 3D Profiler and analyzed using fractal dimension D,scale coefficient C and characteristic roughness Ra ＊based on root mean square（RMS） method.The characterization effects of the three parameters are discussed and compared.The results obtained show that there exists remarkable fractal feature of surface topography during running-in process,both D and Ra ＊increase gradually,while C decreases slowly as the wear-in process goes on,and all parameters tend to be stable when the wear process steps into the normal wear process.Ra ＊illustrates higher sensitivity for rough surface characterization compared with the other two parameters.In addition,the running-in test carried with a set of identical surface properties is more scientific and reasonable than the traditional one.The proposed research further indicates that the fractal method can quantitatively measure the rough surface,which also provides an evidence for running-in process identification and tribology design.
文摘 Lung cancer is the most common cause of death from cancer in males,accounting for more than 1.4 million deaths in 2008.It is a growing concern in China,Asia and Africa as well.Accurate staging of the disease is an important part of the management as it provides estimation of patient’s prognosis and identifies treatment sterategies.It also helps to build a database for future staging projects.A major revision of lung cancer staging has been announced with effect from January 2010.The new classification is based on a larger surgical and non-surgical cohort of patients,and thus more accurate in terms of outcome prediction compared to the previous classification.There are several original papers regarding this new classification which give comprehensive description of the methodology,the changes in the staging and the statistical analysis.This overview is a simplified description of the changes in the new classification and their potential impact on patients’ treatment and prognosis.
文摘Tectonic movements formed several unconfor- mities in the north-west margin of the Junggar basin. Based on data of outcrop, core, and samples, the unconformity is a structural body whose formation associates with weath- ering, leaching, and onlap. At the same time, the structural body may be divided into three layers, including upper layer, mid layer, and lower layer. The upper layer with good primary porosity serves as the hydrocarbon migration system, and also accumulates the hydrocarbon. The mid layer with compactness and ductility can play a role as cap rock, the strength of which increases with depth. The lower layer with good secondary porosity due to weathering and leaching can form the stratigraphic truncation traps. A typical stratigraphie reservoir lying in the unconformity between the Jurassic and Triassic in the north-west margin of the Junggar basin was meticulously analyzed in order to reveal the key controlling factors. The results showed that the hydrocarbon distribution in the stratigraphic onlap reservoirs was controlled by the onlap line, the hydro- carbon distribution in the stratigraphic truncation reser- voirs was confined by the truncation line, and the mid layer acted as the key sealing rock. So a conclusion was drawn that ＂two lines （onlap line and truncation line） and a body （unconformity structural body）＂ control the formation and distribution of stratigraphic reservoirs.
基金supported by National Natural Science Foundation of China(Grant No.21106151,21173226)Ministry of Science & Technology of China under the key technologies R&D program (No.2012BAA03B03)Chinese Academy of Sciences under KGZDEW-302-1,and UK EPSRC under EP/K002252/1
文摘Na2CO3/MgO composites with added multi-walled carbon nanotubes （MWCNTs） were prepared and tested as phase change materials （PCMs） for thermal energy storage. Na2CO3/MgO composite PCMs were prepared and their chemical compatibility and thermal stability were studied. MWCNTs introduced with Na2CO3/MgO composite PCMs were also investigated and scanning electron microscopy （SEM） characterization was used to demonstrate the uniform dispersion of MWCNTs in Na2CO3/MgO composite PCMs. The composites with added MWCNTs still display good thermal stability with mass losses lower than 5%. Introducing MWCNTs into composite Na2CO3/MgO PCMs by material formation/calcination signifi.cantly enhances the thermal conductivity of the composite PCMs. The thermal conductivity of the composite PCMs was found to increase with an increase in the weight fraction of the added MWCNTs and an increase in the testing temperature. This study may present a promising way to prepare high temperature phase change materials with superior properties such as improved thermal stability.
基金supported by UK EPSRC under grants EP/F023014/1 and EP/F000464/1a collaborative research fund from the Institute of Process Engineering of Chinese Academy of Sciences
文摘This short communication reports our recent work on the synthesis and characterisation ofmicrocapsules of phase change materials using silica as the shell material through a one-step method. The method uses no surfactants or dispersants for stabilising the capsules. The results show that the one-step method allows the tuning of the size and polydispersity of the capsules, and the use of different core materials. Analyses of the capsules show that they contain about 65% phase change materials. The results also suggest no need for a stabilising agent due to self-stabilisation by the amine groups. Further work is underway to investigate the mechanical and thermal properties of the microcapsules and the scale-up of the method.
