The evolution of microstructure and microhardness was studied in a commercial tungsten-25%rhenium(mass fraction)(W-25Re)alloy processed by the high pressure torsion(HPT)procedure under a pressure of7.7GPa up to10revol...The evolution of microstructure and microhardness was studied in a commercial tungsten-25%rhenium(mass fraction)(W-25Re)alloy processed by the high pressure torsion(HPT)procedure under a pressure of7.7GPa up to10revolutions at different temperatures.The results show that the samples processed by10revolutions at room temperature could have the smallest grain size at around0.209μm.High saturation hardness(HV^1200)could be achieved after the rapid strengthening stage for samples processed by10revolutions both at room temperature and at573K.Microstructural observation and analysis from Hall-Patch relationship could reveal that grain refinement and grain boundaries strengthening are the main factors of hardening mechanism in W-25Re alloy.It is also demonstrated that sintered W-25Re sample may have brittle phase separation phenomenon after HPT processing.展开更多
To the accomplishment of this article, we have chosen, as a case study, a small Goiana construction company that acted in the market of social housing. The main goal of this work is to analyze the fundamental aspects ...To the accomplishment of this article, we have chosen, as a case study, a small Goiana construction company that acted in the market of social housing. The main goal of this work is to analyze the fundamental aspects related to the management of the flow of supplies in civil construction to achieve a greater streamlining of logistic processes involved in supplying material. A checklist was developed for the purpose of data collection, and it was applied by means of an interview with the person in charge of the purchase department of the enterprise. In addition, this person is the engineer of the site. Taking into account the exploratory feature of this research, the construction site was visited so that some issues, such as quality aspects, losses, cleanliness and organization, could be observed. This on-site data collection visit was carried out through visual analyses and photographs. The obtained results were subdivided into a quantitative and a qualitative analysis. In this way, it was possible to see that the production process still has many phases to be improved. What is more, it was possible to see that the construction company knows its flaws and necessities to improve its processes although the final result does not have the expected quality. Being aware of this need for improvement, the construction company aims at having an affordable price product to the target public, especially when it is associated to an image that shows quality.展开更多
Hevea brasiliensis Muell. Arg. is an important industrial crop for natural rubber production. Latex biosynthesis occurs in the cytoplasm of highly specialized latex cells and latex bleeds out when the bark is tapped. ...Hevea brasiliensis Muell. Arg. is an important industrial crop for natural rubber production. Latex biosynthesis occurs in the cytoplasm of highly specialized latex cells and latex bleeds out when the bark is tapped. Ethylene stimulation acts by increasing latex flow to the cells of inner bark from the latex cells, increasing yield and may affect the physical properties of rubberwood. The aim of this work was to assess the permeability properties of ethylene treated rubberwood （TRW） relative to untreated rubberwood （URW）, because in wood industrial technology, permeability relates to bondability and wood preservative treatments. The Hevea samples were of PRIM 600 strain, from 20-25 years old rubber trees. The TRW rubber trees had been stimulated by ethylene gas for six years. The rubberwood specimens were collected at a single plot of plantation to minimize variations in soil fertility, environmental exposures and silvicultural treatments at Tumbon Chaibury, Amphor Chaibury, Suratthani Province, Thailand. The moisture contents （MC） of fresh rubberwood were significantly different （P 〈 0.05） at 75% for TRW and 64% for URW. The permeability experiment followed Darcy＇s law, and the hydrostatic pressure was controlled. The average 0.005 Darcy water permeability of TRW was significantly higher than the 0.001 Darcy for URW. Water absorptions during 4 h water immersion of rubberwood blocks differed significantly, and TRW had higher absorption than URW also across 6 d of immersion. Scanning electron microscope （SEM） imaging showed anatomical effects that contribute to the fivefold permeability increase.展开更多
On May 12, 2008, a magnitude 8.0 earthquake hit Wenchuan County, Sichuan Province resulted in great loss of life and properties.Besides, abundant landslides and slope failures were triggered in the most seriously hit ...On May 12, 2008, a magnitude 8.0 earthquake hit Wenchuan County, Sichuan Province resulted in great loss of life and properties.Besides, abundant landslides and slope failures were triggered in the most seriously hit areas and caused disastrous damages to infrastructures and public facilities.Moreover, abundant unstable slopes caused by the quake have the potential to cause damages for a considerable long period of time.The variety of these slopes and the corresponding treatments are connected with the topographical and geological conditions of the sites.It is decided to document and identify some of these major slope instabilities caused by the earthquake and their treatments.The paper shows the condition of a road in Dujiangyan through in situ explorations.The case history showed significant implications to the reconstruction of the quake-hit regions and future disaster prevention and management works.展开更多
In Eastern South America, high altitude grasslands represent a mountain system that has a high number of endemic species. However, studies on the ecology of plant communities in these environments remain scarce. We ai...In Eastern South America, high altitude grasslands represent a mountain system that has a high number of endemic species. However, studies on the ecology of plant communities in these environments remain scarce. We aimed to evaluate the patterns of biodiversity and structure of plant communities from rocky outcrops in high altitude grasslands of three areas at the Caparaó National Park, southeastern Brazil, by sampling 300 randomly distributed plots. Then, we compared the floristic composition, relative abundance, and biological and vegetation spectra among areas. We classified species as endemic and non-endemic and verified the occurrence of endangered species. Species richness was evaluated by rarefaction analysis on the sampling units. The importance value and species abundance distribution(SAD) models were assessed. We also performed an indicator species analysis. We sampled 58 species belonging to 49 genera and 32 families. The number of species decreased with increasing altitude, with significant differences being observed among areas regarding richness, abundance, and cover. Of the total number of species, 10 are endemic to the Caparaó National Park and 17 are listed on the Brazilian Red List of endangered species. The dominant families on all peaks were Asteraceae and Poaceae. The SAD models showed lognormal and geometric distributions, corroborating the fact that 10 species that were common to all three areas were also the most dominant ones in the communities and showed the highest importance values, which ranged between 35% and 60%. Indicator species analysis revealed that 28 species(48.27%) were indicators. Of these, 42.85% had maximum specificity, meaning that they occurred only in one area. Thus, the number of species per life form ratio was similar among areas, yet vegetation spectra differed, especially for hemicryptophytes. The altimetric difference among the areas showed to be a very important driver in the community assembly, influencing the evaluated variables, however, other drivers as soil depth, slope and water could also influence the community structure on a smaller and local spatial scale.展开更多
The objective of this research was to develop the causal relationship model of firm characteristics factors and good corporate governance affecting the performance of the companies listed on the Stock Exchange of Thai...The objective of this research was to develop the causal relationship model of firm characteristics factors and good corporate governance affecting the performance of the companies listed on the Stock Exchange of Thailand. The developed model consisted of three latent variables and eight observable variables. The sample of this study was 338 companies listed on the Stock Exchange of Thailand. Data are from annual reports （form-56）, annual financial statements and notes to the fmancial statements during the years 2010-2013. The statistics used in this study were descriptive statistics. The causal model was analyzed through a path analysis with LISREL 8.80 Student Edition. The results showed as follows. By testing the consistence of the causal model of finn characteristics （CHA）, the assumed model was consistent with empirical data. Based on the statistical test, the Chi-Square was 22.08. The statistical probability （p） was 0.077, the degree of freedom （dO was to 0, 2/2 was 1.58, RMSEA was 0.041, SRMR was 0.037, GFI was 0.98, CFI was 0.99, AGFI was 0.96. The latent variable of firm characteristics （CHA） had directly negative impact on performance （PAL） with a statistical significance level of 0.01. A path coefficient was 0.18. However, CHA variable did not indirectly influence performance （PAL） and it had directly negative impact on good corporate governance （GGN） with a path coefficient of 0.02 without statistical significance level. The latent variable of good corporate governance （GGN） had directly positive impact on the performance （PAL） with a statistical significance level of 0.05, with a path coefficient of 0.18.展开更多
A novel composite charged mosaic membrane(CCMM) was prepared via interfacial polymerization(IP) of polyamine[poly(epichlorohydrin amine) ]and trimesoyl chloride(TMC) on the polyethersulfone(PES) support. Fourier trans...A novel composite charged mosaic membrane(CCMM) was prepared via interfacial polymerization(IP) of polyamine[poly(epichlorohydrin amine) ]and trimesoyl chloride(TMC) on the polyethersulfone(PES) support. Fourier transform infrared spectroscopy(FT-IR) ,environmental scanning electron microscopy(ESEM) ,atomic force microscopy(AFM) and water contact angle analysis were applied to characterize the resulted CCMM.The FT-IR spectrum indicates that TMC reacts sufficiently with polyamine.ESEM and AFM pictures show that the IP process produces a dense selective layer on the support membrane.The water contact angle of the CCMM is smaller than that of the substrate membrane because of the cross-linked hydrophilic polyamine network.Several factors affecting the IP reaction and the performance of the CCMM,such as monomer concentration,reaction time,pH value of aqueous phase solution and post-treatment,were studied.The pure water flux of the optimized CCMM is 14.73 L·m -2 ·h -1 ·MPa -1 at the operating pressure of 0.4 MPa.The values of separation factorαfor NaCl/PEG1000/water and MgCl2/PEG1000/water are 11.89 and 9.96,respectively.These results demonstrate that CCMM is promising for the separation of low-molecular-weight organics from their salt aqueous solutions.展开更多
The present research will concentrate on the topic of Fourier analysis on fractals.It mainly deals with the problem of determining spectral self-affine measures on the typical fractals:the planar Sierpinski family.The...The present research will concentrate on the topic of Fourier analysis on fractals.It mainly deals with the problem of determining spectral self-affine measures on the typical fractals:the planar Sierpinski family.The previous researches on this subject have led to the problem within the possible fifteen cases.We shall show that among the fifteen cases,the nine cases correspond to the spectral measures,and reduce the remnant six cases to the three cases.Thus,for a large class of such measures,their spectrality and non-spectrality are clear.Moreover,an explicit formula for the existent spectrum of a spectral measure is obtained.We also give a concluding remark on the remnant three cases.展开更多
基金Project(11402264)supported by the National Natural Science Foundation of ChinaProject(BK20160182)supported by the Natural Science Foundation of Jiangsu Province,ChinaProjects(JUSRP116027,JUSRP51732B)supported by the Fundamental Research Funds from Jiangnan University,China
文摘The evolution of microstructure and microhardness was studied in a commercial tungsten-25%rhenium(mass fraction)(W-25Re)alloy processed by the high pressure torsion(HPT)procedure under a pressure of7.7GPa up to10revolutions at different temperatures.The results show that the samples processed by10revolutions at room temperature could have the smallest grain size at around0.209μm.High saturation hardness(HV^1200)could be achieved after the rapid strengthening stage for samples processed by10revolutions both at room temperature and at573K.Microstructural observation and analysis from Hall-Patch relationship could reveal that grain refinement and grain boundaries strengthening are the main factors of hardening mechanism in W-25Re alloy.It is also demonstrated that sintered W-25Re sample may have brittle phase separation phenomenon after HPT processing.
文摘To the accomplishment of this article, we have chosen, as a case study, a small Goiana construction company that acted in the market of social housing. The main goal of this work is to analyze the fundamental aspects related to the management of the flow of supplies in civil construction to achieve a greater streamlining of logistic processes involved in supplying material. A checklist was developed for the purpose of data collection, and it was applied by means of an interview with the person in charge of the purchase department of the enterprise. In addition, this person is the engineer of the site. Taking into account the exploratory feature of this research, the construction site was visited so that some issues, such as quality aspects, losses, cleanliness and organization, could be observed. This on-site data collection visit was carried out through visual analyses and photographs. The obtained results were subdivided into a quantitative and a qualitative analysis. In this way, it was possible to see that the production process still has many phases to be improved. What is more, it was possible to see that the construction company knows its flaws and necessities to improve its processes although the final result does not have the expected quality. Being aware of this need for improvement, the construction company aims at having an affordable price product to the target public, especially when it is associated to an image that shows quality.
文摘Hevea brasiliensis Muell. Arg. is an important industrial crop for natural rubber production. Latex biosynthesis occurs in the cytoplasm of highly specialized latex cells and latex bleeds out when the bark is tapped. Ethylene stimulation acts by increasing latex flow to the cells of inner bark from the latex cells, increasing yield and may affect the physical properties of rubberwood. The aim of this work was to assess the permeability properties of ethylene treated rubberwood （TRW） relative to untreated rubberwood （URW）, because in wood industrial technology, permeability relates to bondability and wood preservative treatments. The Hevea samples were of PRIM 600 strain, from 20-25 years old rubber trees. The TRW rubber trees had been stimulated by ethylene gas for six years. The rubberwood specimens were collected at a single plot of plantation to minimize variations in soil fertility, environmental exposures and silvicultural treatments at Tumbon Chaibury, Amphor Chaibury, Suratthani Province, Thailand. The moisture contents （MC） of fresh rubberwood were significantly different （P 〈 0.05） at 75% for TRW and 64% for URW. The permeability experiment followed Darcy＇s law, and the hydrostatic pressure was controlled. The average 0.005 Darcy water permeability of TRW was significantly higher than the 0.001 Darcy for URW. Water absorptions during 4 h water immersion of rubberwood blocks differed significantly, and TRW had higher absorption than URW also across 6 d of immersion. Scanning electron microscope （SEM） imaging showed anatomical effects that contribute to the fivefold permeability increase.
基金supported by the 973 Program of China (Grant No. 2008CB425803the Open Fund of the Key Laboratory of Marine Geology and Environment, China Academy of Sciences (Grant No. MGE2008KG04)the Open Fund of the Key Laboratory of Mountain Hazards and Surface Process, CAS.
文摘On May 12, 2008, a magnitude 8.0 earthquake hit Wenchuan County, Sichuan Province resulted in great loss of life and properties.Besides, abundant landslides and slope failures were triggered in the most seriously hit areas and caused disastrous damages to infrastructures and public facilities.Moreover, abundant unstable slopes caused by the quake have the potential to cause damages for a considerable long period of time.The variety of these slopes and the corresponding treatments are connected with the topographical and geological conditions of the sites.It is decided to document and identify some of these major slope instabilities caused by the earthquake and their treatments.The paper shows the condition of a road in Dujiangyan through in situ explorations.The case history showed significant implications to the reconstruction of the quake-hit regions and future disaster prevention and management works.
文摘In Eastern South America, high altitude grasslands represent a mountain system that has a high number of endemic species. However, studies on the ecology of plant communities in these environments remain scarce. We aimed to evaluate the patterns of biodiversity and structure of plant communities from rocky outcrops in high altitude grasslands of three areas at the Caparaó National Park, southeastern Brazil, by sampling 300 randomly distributed plots. Then, we compared the floristic composition, relative abundance, and biological and vegetation spectra among areas. We classified species as endemic and non-endemic and verified the occurrence of endangered species. Species richness was evaluated by rarefaction analysis on the sampling units. The importance value and species abundance distribution(SAD) models were assessed. We also performed an indicator species analysis. We sampled 58 species belonging to 49 genera and 32 families. The number of species decreased with increasing altitude, with significant differences being observed among areas regarding richness, abundance, and cover. Of the total number of species, 10 are endemic to the Caparaó National Park and 17 are listed on the Brazilian Red List of endangered species. The dominant families on all peaks were Asteraceae and Poaceae. The SAD models showed lognormal and geometric distributions, corroborating the fact that 10 species that were common to all three areas were also the most dominant ones in the communities and showed the highest importance values, which ranged between 35% and 60%. Indicator species analysis revealed that 28 species(48.27%) were indicators. Of these, 42.85% had maximum specificity, meaning that they occurred only in one area. Thus, the number of species per life form ratio was similar among areas, yet vegetation spectra differed, especially for hemicryptophytes. The altimetric difference among the areas showed to be a very important driver in the community assembly, influencing the evaluated variables, however, other drivers as soil depth, slope and water could also influence the community structure on a smaller and local spatial scale.
文摘The objective of this research was to develop the causal relationship model of firm characteristics factors and good corporate governance affecting the performance of the companies listed on the Stock Exchange of Thailand. The developed model consisted of three latent variables and eight observable variables. The sample of this study was 338 companies listed on the Stock Exchange of Thailand. Data are from annual reports （form-56）, annual financial statements and notes to the fmancial statements during the years 2010-2013. The statistics used in this study were descriptive statistics. The causal model was analyzed through a path analysis with LISREL 8.80 Student Edition. The results showed as follows. By testing the consistence of the causal model of finn characteristics （CHA）, the assumed model was consistent with empirical data. Based on the statistical test, the Chi-Square was 22.08. The statistical probability （p） was 0.077, the degree of freedom （dO was to 0, 2/2 was 1.58, RMSEA was 0.041, SRMR was 0.037, GFI was 0.98, CFI was 0.99, AGFI was 0.96. The latent variable of firm characteristics （CHA） had directly negative impact on performance （PAL） with a statistical significance level of 0.01. A path coefficient was 0.18. However, CHA variable did not indirectly influence performance （PAL） and it had directly negative impact on good corporate governance （GGN） with a path coefficient of 0.02 without statistical significance level. The latent variable of good corporate governance （GGN） had directly positive impact on the performance （PAL） with a statistical significance level of 0.05, with a path coefficient of 0.18.
基金Supported by the National High Technology Research and Development Program of China（2008AA06Z330） the National Natural Science Foundation of China（20676125） the Technician Service Enterprise Action Program（2009GJD00048）
文摘A novel composite charged mosaic membrane(CCMM) was prepared via interfacial polymerization(IP) of polyamine[poly(epichlorohydrin amine) ]and trimesoyl chloride(TMC) on the polyethersulfone(PES) support. Fourier transform infrared spectroscopy(FT-IR) ,environmental scanning electron microscopy(ESEM) ,atomic force microscopy(AFM) and water contact angle analysis were applied to characterize the resulted CCMM.The FT-IR spectrum indicates that TMC reacts sufficiently with polyamine.ESEM and AFM pictures show that the IP process produces a dense selective layer on the support membrane.The water contact angle of the CCMM is smaller than that of the substrate membrane because of the cross-linked hydrophilic polyamine network.Several factors affecting the IP reaction and the performance of the CCMM,such as monomer concentration,reaction time,pH value of aqueous phase solution and post-treatment,were studied.The pure water flux of the optimized CCMM is 14.73 L·m -2 ·h -1 ·MPa -1 at the operating pressure of 0.4 MPa.The values of separation factorαfor NaCl/PEG1000/water and MgCl2/PEG1000/water are 11.89 and 9.96,respectively.These results demonstrate that CCMM is promising for the separation of low-molecular-weight organics from their salt aqueous solutions.
基金supported by National Natural Science Foundation of China (Grant No.11171201)
文摘The present research will concentrate on the topic of Fourier analysis on fractals.It mainly deals with the problem of determining spectral self-affine measures on the typical fractals:the planar Sierpinski family.The previous researches on this subject have led to the problem within the possible fifteen cases.We shall show that among the fifteen cases,the nine cases correspond to the spectral measures,and reduce the remnant six cases to the three cases.Thus,for a large class of such measures,their spectrality and non-spectrality are clear.Moreover,an explicit formula for the existent spectrum of a spectral measure is obtained.We also give a concluding remark on the remnant three cases.
