Small and Medium-sized Enterprises (SMEs) are considered the backbone of global economy, but they often face cyberthreats which threaten their financial stability and operational continuity. This work aims to offer a ...Small and Medium-sized Enterprises (SMEs) are considered the backbone of global economy, but they often face cyberthreats which threaten their financial stability and operational continuity. This work aims to offer a proactive cybersecurity approach to safeguard SMEs against these threats. Furthermore, to mitigate these risks, we propose a comprehensive framework of practical and scalable cybersecurity measurements/protocols specifically for SMEs. These measures encompass a spectrum of solutions, from technological fortifications to employee training initiatives and regulatory compliance strategies, in an effort to cultivate resilience and awareness among SMEs. Additionally, we introduce a specially designed a Java-based questionnaire software tool in order to provide an initial framework for essential cybersecurity measures and evaluation for SMEs. This tool covers crucial topics such as social engineering and phishing attempts, implementing antimalware and ransomware defense mechanisms, secure data management and backup strategies and methods for preventing insider threats. By incorporating globally recognized frameworks and standards like ISO/IEC 27001 and NIST guidelines, this questionnaire offers a roadmap for establishing and enhancing cybersecurity measures.展开更多
With a continuously increasing population and better food consumption levels, im- proving the efficiency of arable land use and increasing its productivity have become funda- mental strategies to meet the growing food...With a continuously increasing population and better food consumption levels, im- proving the efficiency of arable land use and increasing its productivity have become funda- mental strategies to meet the growing food security needs in China. A spatial distribution map of medium- and low-yield cropland is necessary to implement plans for cropland improvement In this study, we developed a new method to identify high-, medium-, and low-yield cropland from Moderate Resolution Imaging Spectroradiometer （MODIS） data at a spatial resolution of 500 m. The method could be used to reflect the regional heterogeneity of cropland productiv- ity because the classification standard was based on the regionalization of cropping systems in China. The results showed that the proportion of high-, medium-, and low-yield cropland in China was 21%, 39%, and 40%, respectively. About 75% of the low-yield cropland was lo- cated in hilly and mountainous areas, and about 53% of the high-yield cropland was located in plain areas. The five provinces with the largest area of high-yield cropland were all located in the Huang-Huai-Hai region, and the area amounted to 42% of the national high-yield cropland area. Meanwhile, the proportion of high-yield cropland was lower than 15% in Hei- Iongjiang, Sichuan, and Inner Mongolia, which had the largest area allocated to cropland in China. If all the medium-yield cropland could be improved to the productive level of high-yield cropland and the low-yield cropland could be improved to the level of medium-yield cropland, the total productivity of the land would increase 19% and 24%, respectively.展开更多
AIM:To evaluate the outcomes of patients withmedium-sized hepatocellular carcinoma(HCC)who underwent percutaneous microwave ablation(MWA).METHODS:We retrospectively reviewed all patients with a single medium-sized HCC...AIM:To evaluate the outcomes of patients withmedium-sized hepatocellular carcinoma(HCC)who underwent percutaneous microwave ablation(MWA).METHODS:We retrospectively reviewed all patients with a single medium-sized HCC who underwent percutaneous MWA from January 2010 to January2013.Technical success,technical effectiveness and complications were subsequently observed.Survival curves were constructed using the Kaplan-Meier method.The Cox proportional hazards model was fitted to each variable.The relative prognostic significance o f t h e va r i a b l e s fo r p re d i c t i n g ove ra l l s u r v i va l rate,recurrence-free survival rate and local tumor recurrence(s)was assessed using univariate analysis.All variables with a P value<0.20 were subjected to multivariate analysis.RESULTS:The study included 182 patients(mean age,58 years;age range:22-86 years)with a single HCC(mean size,3.72±0.54 cm;range:3.02-5.00cm).The estimated technical effectiveness rate was93%in 182 patients.The major complication rate was2.7%(5/182),including liver abscess in 4 cases,and abdominal bleeding at the puncture site in 1 case.Thirty-day mortality rate was 0.5%(1/182).One patient died due to liver abscess-related septicemia.Cumulative recurrence-free survival and overall survival(OS)rates were 51%,36%,27%and 89%,74%,60%at 1,2,and 3 years,respectively.Age(P=0.017)and tumor diameter(P=0.029)were independent factors associated with local tumor recurrence.None of the factors had a statistically significant impact on recurrence-free survival.Serum albumin level(P=0.009)and new lesion(s)(P=0.029)were independently associated with OS.CONCLUSION:Percutaneous MWA is a relatively safe and effective treatment for patients with medium-sized HCC.展开更多
Based on the research of juvenile (2, 3, 4 months) growth and survival of three populations of two different geographic areas in Chlamys farreri from Russian and China and their F1 hybrids derived from Chinese cultura...Based on the research of juvenile (2, 3, 4 months) growth and survival of three populations of two different geographic areas in Chlamys farreri from Russian and China and their F1 hybrids derived from Chinese cultural population (CC) (?) × Russian population (RW) (?) , Chinese wild population (CW) (?) × Russian population (RW) (?), Russian population (RW) (?) × Chinese wild population (CW) (?) , the study of the medium-term (6, 8, 10, 12 months) growth and development of Chlamys farreri was carried out. The four determined results indicated that there existed different extent heterosis (3% -52%) for the growth in three types of F1 hybrids, and the offspring derived from CC(?) ×R(?) had a stronger heterosis among the crosses at the medium-term; the uptrend among traits are wet weight >shell width>shell length> shell height, Chinese cultural population could be recognized as excellent parent, and seasonal variations influence very much on the daily increment and growth rate of each trait of Chlamys farreri and it is only able to survive and could barely grow in winter (6-8 months), but grows fast in temperate season (10-12 months).展开更多
A novel high nitrogen medium-entropy alloy CrCoNiN, which had higher strength and slightly lower ductility than CrCoNi alloy, was successfully manufactured by pressurized metallurgy.The microstructure and corrosion be...A novel high nitrogen medium-entropy alloy CrCoNiN, which had higher strength and slightly lower ductility than CrCoNi alloy, was successfully manufactured by pressurized metallurgy.The microstructure and corrosion behaviour were investigated by microscopic, electrochemical and spectroscopic methods. The results indicated that nitrogen existed in the form of Cr2N precipitates and uniformly distributed N atoms, and nitrogen alloying significantly refined the grain size. Besides, nitrogen enriched on the outmost surface of passive film and metal/film interface as ammonia （NH3 and NH4^＋） and CrN, respectively. The significant improvement of corrosion resistance of CrCoNiN was attributed to the lower metastahle pitting susceptibility together with thicker, less defective and more compact passive film.展开更多
Background:The search for alternatives to antibiotics in pig production has increased the interest in natural resources with antimicrobial properties,such as medium-chain fatty acids(MCFA)as in-feed additives.This stu...Background:The search for alternatives to antibiotics in pig production has increased the interest in natural resources with antimicrobial properties,such as medium-chain fatty acids(MCFA)as in-feed additives.This study evaluated the potential of a novel blend of MCFA salts(DIC)from distilled coconut oil with a lauric acid content to reduce enteropathogens and control intestinal diseases around weaning.Two experimental disease models were implemented in early-weaned piglets,consisting of two oral challenges:Salmonella Typhimurium(1.2×10~8 CFU)or enterotoxigenic Escherichia coli(ETEC)F4(1.5×10~9 CFU).The parameters assessed were:animal performance,clinical signs,pathogen excretion,intestinal fermentation,immune-inflammatory response,and intestinal morphology.Results:The Salmonella challenge promoted an acute course of diarrhea,with most of the parameters responding to the challenge,whereas the ETEC F4 challenge promoted a mild clinical course.A consistent antipathogenic effect of DIC was observed in both trials in the hindgut,with reductions in Salmonella spp.plate counts in the cecum(P=0.03)on d 8 post-inoculation(PI)(Salmonella trial),and of enterobacteria and total coliform counts in the ileum and colon(P<0.10)on d 8 PI(ETEC F4 trial).When analyzing the entire colonic microbiota(16 S rRNA gene sequencing),this additive tended(P=0.13)to reduce the Firmicutes/Bacteroidetes ratio and enriched Fibrobacteres after the Salmonella challenge.In the ETEC F4 challenge,DIC prompted structural changes in the ecosystem with increases in Dialister,and a trend(P=0.14)to increase the Veillonellaceae family.Other parameters such as the intestinal fermentation products or serum pro-inflammatory mediators were not modified by DIC supplementation,nor were the histological parameters.Only the intraepithelial lymphocyte(IEL)counts were lowered by DIC in animals challenged with Salmonella(P=0.07).With ETEC F4,the IEL counts were higher with DIC on d 8 PI(P=0.08).Conclusions:This study confirms the potential activity of this MCFA salts mixture to reduce intestinal colonization by opportunistic pathogens such as Salmonella or E.coli and its ability to modulate colonic microbiota.These changes could explain to some extent the local immune cell response at the ileal level.展开更多
An in situ high-energy X-ray diffraction(HE-XRD) technique was mainly used to investigate the micromechanical behavior of medium-Mn Fe-0.12 C-10.16 Mn-1.87 Al(in wt%) transformation-induced plasticit(TRIP) steel subje...An in situ high-energy X-ray diffraction(HE-XRD) technique was mainly used to investigate the micromechanical behavior of medium-Mn Fe-0.12 C-10.16 Mn-1.87 Al(in wt%) transformation-induced plasticit(TRIP) steel subjected to intercritical annealing at 625℃, 650℃, 675℃ and 700℃ for 1 h. As the intercritical annealing temperature increased, the volume fraction of retained austenite(RA) and ultimate tensilstress(UTS) increased, while the Lüders strain and yield stress(YS) decreased. The incremental workhardening exponent of experimental steel increased with increasing intercritical annealing temperatureThe overall trend of the transformation kinetics of the RA with respect to the true strain followed thsigmoidal shape predicted by the Olson and Cohen(OC) model. Load partitioning occurred among the ferrite, austenite and martensite immediately after entering the yielding stage. Because the stability of thRA decreased with increasing intercritical annealing temperature, the load undertaken by the martensitincreased. The moderate transformation kinetics of the RA and effective load partitioning among constituent phases were found to contribute to a favorable combination of strength and ductility for thimedium-Mn TRIP steel.展开更多
Objective To investigate activation of brown adipose tissue （BAT） stimulated by medium-chain triglyceride （MCT）. Methods 30 Male C57BL/6J obese mice induced by fed high fat diet （HFD） were divided into 2 groups,...Objective To investigate activation of brown adipose tissue （BAT） stimulated by medium-chain triglyceride （MCT）. Methods 30 Male C57BL/6J obese mice induced by fed high fat diet （HFD） were divided into 2 groups, and fed another HFD with 2% MCT or long-chain triglyceride （LCT） respectively for 12 weeks. Body weight, blood biochemical variables, interscapular brown fat tissue （IBAT） mass, expressions of mRNA and protein of beta 3-adrenergic receptors （β3-AR）, uncoupling protein-1 （UCP1）, hormone sensitive lipase （HSL）, protein kinase A （PKA）, and adipose triglyceride lipase （ATGL） in IBAT were measured. Results Significant decrease in body weight and body fat mass was observed in MCT group as compared with LCT group （P〈O.05） after 12 weeks. Greater increases in IBAT mass was observed in MCT group than in LCT group （P〈O.05）. Blood TG, TC, LDL-C in MCT group were decreased significantly, meanwhile blood HDL-C, ratio of HDL-C/LDL-C and norepinephrine were increased markedly. Expressions of mRNA and protein of β3-AR, UCP1, PKA, HSL, ATGL in BAT were greater in MCT group than in LCT group （P〈O.05）. Conclusion Our results suggest that MCT stimulated the activation of BAT, possible via norepinephrine pathway, which might partially contribute to reduction of the body fat mass in obese mice fed high fat diet.展开更多
The flow field of molten steel and the interfacial behaviour between molten steel and liquid slag layer in medium-thin slab continuous casting mold with argon gas injection were studied by numerical simulation, in whi...The flow field of molten steel and the interfacial behaviour between molten steel and liquid slag layer in medium-thin slab continuous casting mold with argon gas injection were studied by numerical simulation, in which the effects of nozzle submergence depth and port angle, casting speed, and argon gas flow rate on the flow and the level fluctuation of molten steel were considered. The results show that the molten steel is jetted from the submerged en- try nozzle （SEN） with three ports into the mold and forms three recirculation zones including one upper recireulation zone and two lower recirculation zones. Argon gas injection results in a secondary vortex flow in the upper zone near the nozzle. For a given casting speed and argon gas flow rate, increasing the side port angle and submergence depth of nozzle can effectively restrain the steel/slag interracial fluctuation. Increasing the casting speed would prick up the level fluctuation. For a fixed casting speed, argon gas flow rate has a critical value, the interracial fluctuation with argon gas injection are stronger than the case without argon gas injection when the argon gas flow rate is less than the critical value, but when the argon gas flow rate exceeds the critical value, the level fluctuation is calmer than that without argon gas injection.展开更多
The effects of the basal and top-dressing nitrogen (N) on N uptake and translocation, N utilization efficiency, grain yieldand quality of medium-gluten winter wheat Yangmai 10 were studied from 2000 to 2002. The main ...The effects of the basal and top-dressing nitrogen (N) on N uptake and translocation, N utilization efficiency, grain yieldand quality of medium-gluten winter wheat Yangmai 10 were studied from 2000 to 2002. The main results were as follows.Nitrogen content and nitrogen accumulation in plant at maturity increased with the amount of N application. Grain proteincontent and wet gluten content were significantly correlated with applied N. There was a significantly positive correlationbetween nitrogen accumulation before anthesis (NBA) and basal N fertilizer, and between nitrogen accumulation afteranthesis (NAA) and top-dressing N. N accumulated in grains was significantly correlated to NBA, NAA and N translocationfrom vegetative organs after anthesis (NTVA). NBA was significantly correlated with N application, but NAA and NTVAhad a quadratic curve correlation with applied N. N fertilizer use efficiency (NUE) had a quadratic curve correlation withapplied N, and the NUE was high when basal and top-dressing N was equally applied. For the medium-gluten wheatYangmai 10 under the same N application ratio, there was a N-regulating effect when the N application was less than266.55 kg ha-1, a stagnation of yield and quality when N application ranged from 266.55 to 309.08 kg ha-1, and an excessiveN application when the N application rate was greater than 309.08 kg ha-1. Under the conditions of this experiment, theprecise N application is 220-270 kg ha-1 with basal and top-dressing N equally used when a grain yield of more than 6 750kg ha-1, protein content higher than 12%, wet gluten content more than 30% and NUE greater than 40% could be obtained.展开更多
The flux cored wires with different rare earth oxide additions for hardfacing the workpieces of medium-high carbon steel were developed. The microstrucmre of the hardfacing layer was observed using the optical microsc...The flux cored wires with different rare earth oxide additions for hardfacing the workpieces of medium-high carbon steel were developed. The microstrucmre of the hardfacing layer was observed using the optical microscopy. The average dimension of primary austenite grains in hardfacing layer was measured by image analyzer. The primary austenite grain growth activation energy and index were calculated according to Sellars＇s mode and Beck formula, respectively. Moreover, the effect of rare earth oxide on the growth dynamics of primary aus- tenite grain was analyzed, and then discussed with the misfit theory. The experimental results showed that, by adding rare earth oxide, the av- erage dimension of primary austenite grains in hardfacing layer of medium-high carbon steel decreased, and it was the smallest when the ad- dition of rare earth oxide was 5.17 wt.%. Meanwhile, at this rare earth oxide addition, the primary austenite grain growth activating energy in hardfacing layer was the largest, while its index was the smallest. The calculated results indicated that the primary austenite grain could be refined because LaAlO3 as heterogeneous nuclei of γ-Fe was the most effective.展开更多
The microstructure and mechanical properties of NiCrMoV-and NiCrSi-alloyed medium-carbon steels were investigated after multiple tempering. After austenitising, the steels were hardened by oil quenching and subsequent...The microstructure and mechanical properties of NiCrMoV-and NiCrSi-alloyed medium-carbon steels were investigated after multiple tempering. After austenitising, the steels were hardened by oil quenching and subsequently double or triple tempered at temperatures from 250 to 500 °C. The samples were characterised using scanning electron microscopy and X-ray diffraction, while the mechanical properties were evaluated by Vickers hardness testing, V-notched Charpy impact testing and tensile testing. The results showed that the retained austenite was stable up to 400 °C and the applied multiple tempering below this temperature did not lead to a complete decomposition of retained austenite in both steels. It was also found that the microstructure, hardness and impact toughness varied mainly as a function of tempering temperature,regardless of the number of tempering stages. Moreover, the impact toughness of NiCrMoV steel was rather similar after single/triple tempering at different temperatures, while NiCrSi steel exhibited tempered martensite embrittlement after single/double tempering at 400 °C. The observed difference was mainly attributed to the effect of precipitation behaviour due to the effect of alloying additions in the studied steels.展开更多
A new process involving ultra-fast cooling（UFC）and on-line tempering（OLT）was proposed to displace austempering process,which usually implements in a salt/lead bath and brings out serious pollution in the industria...A new process involving ultra-fast cooling（UFC）and on-line tempering（OLT）was proposed to displace austempering process,which usually implements in a salt/lead bath and brings out serious pollution in the industrial application.The optimization of the new process,involving the evolution of the microstructure of medium-carbon steel during various cooling paths,was studied.The results show that the cooling path affected the final microstructure in terms of the fraction of pearlite,grain size and distribution of cementite in pearlite.Increasing the cooling rate or decreasing the OLT temperature contributes to restraining the transformation from austenite to ferrite,and simultaneously retains more austenite for the transformation of pearlite.It is also noted that bainite was observed in the microstructure at the cooling rate of 45℃/s and the OLT temperature of 500℃.Through either increasing the cooling rate or decreasing the OLT temperature,the distribution of cementite in pearlite is more dispersed and grain is refined.Taking the possibility of industrial applications into account,the optimal process of cooling at 45℃/s followed by OLT at 600℃ after hot rolling was determined,which achieves a microstructure containing nearly full pearlite with an average grain size of approximately 7μm and a homogeneously dispersed distribution of cementite in pearlite.展开更多
The delayed fracture behavior of medium carbon high strength spring steel containing different amounts of boron （0. 000 5%, 0. 001 6 %） was studied using sustained load delayed fracture test. The results show that d...The delayed fracture behavior of medium carbon high strength spring steel containing different amounts of boron （0. 000 5%, 0. 001 6 %） was studied using sustained load delayed fracture test. The results show that delayed fracture resistance of boron containing steels is higher than that of conventional steel 60Si2MnA at the same strength level and it increases with the increase of boron eontent from 0. 000 5% to 0. 001 6%. The delayed fracture mode is mainly intergranular in the boron containing steels tempered at 350℃, which indicates that the addition of boron does not change the fracture character. However, the increase of boron content enlarges the size of the crack initia tion area. Further study of phase analysis indicates that most boron is in solid solution, and only a very small quantity of boron is in the M3 （C, B） phase.展开更多
The non-edible camphor tree seed oil was extracted and catalyzed by immobilized lipase for biodiesel production. The oil yield from camphor tree seeds reached 35.2% of seed weight by twice microwave-assisted extractio...The non-edible camphor tree seed oil was extracted and catalyzed by immobilized lipase for biodiesel production. The oil yield from camphor tree seeds reached 35.2% of seed weight by twice microwave-assisted extractions. Gas chromatography showed that free fatty acid content in camphor tree seed oil was 1.88%, and the main fatty acids were capric acid(53.4%) and lauric acid(38.7%). With immobilized lipase Candida sp. 99–125as catalyst, several important factors for reaction conditions were examined through orthogonal experiments.The optimum conditions were obtained: water content and enzyme loading were both 15% with a molar ratio of 1:3.5(oil/ethanol), and the process of alcoholysis was in nine steps at 40 °C for 24 h, with agitation at170 r·min-1. As a result, the medium-chain biodiesel yield was 93.5%. The immobilized lipase was stable when it was used repeatedly for 210 h.展开更多
An ultrafine-grained(UFG) low-carbon medium-manganese steel was fabricated by the heavily warm rolling(HWR) and subsequent quenching, and the effects of annealing temperatures on microstructure and mechanical properti...An ultrafine-grained(UFG) low-carbon medium-manganese steel was fabricated by the heavily warm rolling(HWR) and subsequent quenching, and the effects of annealing temperatures on microstructure and mechanical properties of the UFG HWRed steel were investigated. The results show that the HWRed steel exhibits simultaneous improvements in strength,uniform elongation and work hardening, which is mainly attributed to the refinement of martensitic microstructures. The HWRed steels comprise only a-phase when annealing at lower temperatures below to 550 °C and at higher temperatures above to 700 °C. Whereas, UFG c-austenite is formed by reverse transformation when the HWRed steel was annealed at intermediate temperatures from 550 to 700 °C and the volume fraction increases with increasing annealing temperatures,consequently resulting in a dramatic increase in ductility of the annealed HWRed steels. It was found that the transformed UFG austenite and ferrite remained ～500 nm and ～800 nm in size when the HWRed steel was annealed at 650 and700 °C for 1 h, respectively, showing an excellent thermal stability. Moreover, the HWRed steel annealed at 650 °C exhibits high strength-ductility combinations with a yield strength of 906 MPa, ultimate tensile strength(UTS) of1011 MPa, total elongation(TEL) of 51% and product of strength and elongation(PSE: UTS 9 TEL) of 52 GPa%. It is believed that these excellent comprehensive mechanical properties are closely associated with the UFG austenite formation by reverse transformation and principally attributed to the transformation-induced plasticity(TRIP) effect.展开更多
Based on the analysis of the basic characteristics of medium-and large-sized marine gas fields in Sichuan Basin, combined with the division of major reservoir forming geological units in the marine craton stage and th...Based on the analysis of the basic characteristics of medium-and large-sized marine gas fields in Sichuan Basin, combined with the division of major reservoir forming geological units in the marine craton stage and their control on key hydrocarbon accumulation factors, the distribution law of medium-and large-sized marine carbonate gas fields in the basin was examined and the exploration direction was pointed out. Through the analysis of the periodic stretching-uplifting background, it is concluded that five large scale paleo-rifts, three large scale paleo-uplifts, five large scale paleo erosion surfaces were formed in the marine craton stage of Sichuan Basin, and these geological units control the key reservoir forming factors of medium and large sized gas fields:(1) Large-scale paleo-rifts control the distribution of high-quality hydrocarbon generation centers.(2) The margin of large-scale paleo-rifts, high position of paleo-uplifts and paleo erosion surfaces control the distribution of high-quality reservoirs.(3) Large-scale paleo-rifts, paleo-uplifts, paleo erosion surfaces and present tectonic setting jointly control the formation of many types of large and medium-sized traps.(4) Natural gas accumulation is controlled by the inheritance evolution of traps in large geological units. Based on the comparative analysis of the distribution characteristics of medium-and large-sized gas fields and large geological units, it is proposed that the superimposition relationship between single or multiple geological units and the present structure controls the distribution of medium-and large-sized gas fields, and the "three paleo" superimposed area is the most advantageous. According to the above rules, the main exploration fields and directions of medium-and large-sized marine carbonate gas fields in Sichuan Basin include periphery of Deyang-Anyue paleo-rift, eastern margin of Longmenshan paleo-rift, margins of Kaijiang-Liangping oceanic trough and Chengkou-western Hubei oceanic trough, the high part of the subaqueous paleo-uplifts around Central Sichuan, paleo erosion surfaces of the top boundary of Maokou Formation in eastern and southern Sichuan Basin, paleo erosion surfaces of the top boundary of the Leikoupo Formation in central and western Sichuan Basin.展开更多
A mathematical model for describing the melting process in the medium-frequency induction furnace was developed.Finite difference method was applied to deal with coupling electromagnetic field and temperature field in...A mathematical model for describing the melting process in the medium-frequency induction furnace was developed.Finite difference method was applied to deal with coupling electromagnetic field and temperature field in the melting process.The magnetic induction,temperature distribution and the phase interface moving characteristic during melting of the furnace burden were calculated.The effects of the direct current and inductive heating frequency on the process were analyzed.The simulation results show that:In the direction of burden radius,magnetic induction decreases from the outside of the burden to the center.Solid/liquid interface moves gradually from the outside of the burden to the center.The movement speed increases when the burden begins to melt.In the direction of the burden height,the distribution of eddy current in the surface is accord with the edge effect of the coil.Solid/liquid interface moves gradually from the center to the two sides.The direct current has a greater effect on the electromagnetic field and temperature field than frequency.展开更多
The Zhangjiakou-Penglai fault zone lies in the northern part of North China Plain and extends along the Zhangjiakou-Huailai-Sanhe-Tianjin-Bohai Sea-Penglai-Yantai-North Huanghai Sea line, it is about 900 km long and s...The Zhangjiakou-Penglai fault zone lies in the northern part of North China Plain and extends along the Zhangjiakou-Huailai-Sanhe-Tianjin-Bohai Sea-Penglai-Yantai-North Huanghai Sea line, it is about 900 km long and some 250-km wide in a northwest direction. The 1679 Sanhe-Pinggu M 8.0 and the 1976 Tangshan M7.8 earthquakes occurred in the fault zone. In this paper an analysis of Gutenberg- Richter’s empirical relation and time process of historic and recent earthquakes along the eastern and western segments of the fault zone separated by the 117°line indicates that they obey a Poison process and, hence, a calculation from it yields a cumulative probability of strong earthquake occurrence along the two segments before 2010, i. e. the probability of M6.0 earthquake occurrence is 0.80 along the eastern segment and the probability of M7. 0 earthquake occurrence is 0.76 along the western segment of the fault zone.展开更多
The effect of RE-modifier on the microstructure and mechanical properties of high carbon-medium manganese steel has been investigated in present work.The results showed that the RE-modifier can refine the crystalline ...The effect of RE-modifier on the microstructure and mechanical properties of high carbon-medium manganese steel has been investigated in present work.The results showed that the RE-modifier can refine the crystalline grain of high-carbon medium-manganese steel.The shape and distribution of carbides are improved and the columnar grains and phosphide in grain boundary are eliminated.Consequently,the impact toughness of the steel is increased by more than one time,compared with no addition of RE-modifier.展开更多
文摘Small and Medium-sized Enterprises (SMEs) are considered the backbone of global economy, but they often face cyberthreats which threaten their financial stability and operational continuity. This work aims to offer a proactive cybersecurity approach to safeguard SMEs against these threats. Furthermore, to mitigate these risks, we propose a comprehensive framework of practical and scalable cybersecurity measurements/protocols specifically for SMEs. These measures encompass a spectrum of solutions, from technological fortifications to employee training initiatives and regulatory compliance strategies, in an effort to cultivate resilience and awareness among SMEs. Additionally, we introduce a specially designed a Java-based questionnaire software tool in order to provide an initial framework for essential cybersecurity measures and evaluation for SMEs. This tool covers crucial topics such as social engineering and phishing attempts, implementing antimalware and ransomware defense mechanisms, secure data management and backup strategies and methods for preventing insider threats. By incorporating globally recognized frameworks and standards like ISO/IEC 27001 and NIST guidelines, this questionnaire offers a roadmap for establishing and enhancing cybersecurity measures.
基金STS Project of CAS,No.KFJ-EW-STS-001National Natural Science Foundation of China,No.41430861
文摘With a continuously increasing population and better food consumption levels, im- proving the efficiency of arable land use and increasing its productivity have become funda- mental strategies to meet the growing food security needs in China. A spatial distribution map of medium- and low-yield cropland is necessary to implement plans for cropland improvement In this study, we developed a new method to identify high-, medium-, and low-yield cropland from Moderate Resolution Imaging Spectroradiometer （MODIS） data at a spatial resolution of 500 m. The method could be used to reflect the regional heterogeneity of cropland productiv- ity because the classification standard was based on the regionalization of cropping systems in China. The results showed that the proportion of high-, medium-, and low-yield cropland in China was 21%, 39%, and 40%, respectively. About 75% of the low-yield cropland was lo- cated in hilly and mountainous areas, and about 53% of the high-yield cropland was located in plain areas. The five provinces with the largest area of high-yield cropland were all located in the Huang-Huai-Hai region, and the area amounted to 42% of the national high-yield cropland area. Meanwhile, the proportion of high-yield cropland was lower than 15% in Hei- Iongjiang, Sichuan, and Inner Mongolia, which had the largest area allocated to cropland in China. If all the medium-yield cropland could be improved to the productive level of high-yield cropland and the low-yield cropland could be improved to the level of medium-yield cropland, the total productivity of the land would increase 19% and 24%, respectively.
文摘AIM:To evaluate the outcomes of patients withmedium-sized hepatocellular carcinoma(HCC)who underwent percutaneous microwave ablation(MWA).METHODS:We retrospectively reviewed all patients with a single medium-sized HCC who underwent percutaneous MWA from January 2010 to January2013.Technical success,technical effectiveness and complications were subsequently observed.Survival curves were constructed using the Kaplan-Meier method.The Cox proportional hazards model was fitted to each variable.The relative prognostic significance o f t h e va r i a b l e s fo r p re d i c t i n g ove ra l l s u r v i va l rate,recurrence-free survival rate and local tumor recurrence(s)was assessed using univariate analysis.All variables with a P value<0.20 were subjected to multivariate analysis.RESULTS:The study included 182 patients(mean age,58 years;age range:22-86 years)with a single HCC(mean size,3.72±0.54 cm;range:3.02-5.00cm).The estimated technical effectiveness rate was93%in 182 patients.The major complication rate was2.7%(5/182),including liver abscess in 4 cases,and abdominal bleeding at the puncture site in 1 case.Thirty-day mortality rate was 0.5%(1/182).One patient died due to liver abscess-related septicemia.Cumulative recurrence-free survival and overall survival(OS)rates were 51%,36%,27%and 89%,74%,60%at 1,2,and 3 years,respectively.Age(P=0.017)and tumor diameter(P=0.029)were independent factors associated with local tumor recurrence.None of the factors had a statistically significant impact on recurrence-free survival.Serum albumin level(P=0.009)and new lesion(s)(P=0.029)were independently associated with OS.CONCLUSION:Percutaneous MWA is a relatively safe and effective treatment for patients with medium-sized HCC.
基金This study is contribution No. G199901209 of 973 from the Chinese Basic Research Project and Chinese Postdoctor Found
文摘Based on the research of juvenile (2, 3, 4 months) growth and survival of three populations of two different geographic areas in Chlamys farreri from Russian and China and their F1 hybrids derived from Chinese cultural population (CC) (?) × Russian population (RW) (?) , Chinese wild population (CW) (?) × Russian population (RW) (?), Russian population (RW) (?) × Chinese wild population (CW) (?) , the study of the medium-term (6, 8, 10, 12 months) growth and development of Chlamys farreri was carried out. The four determined results indicated that there existed different extent heterosis (3% -52%) for the growth in three types of F1 hybrids, and the offspring derived from CC(?) ×R(?) had a stronger heterosis among the crosses at the medium-term; the uptrend among traits are wet weight >shell width>shell length> shell height, Chinese cultural population could be recognized as excellent parent, and seasonal variations influence very much on the daily increment and growth rate of each trait of Chlamys farreri and it is only able to survive and could barely grow in winter (6-8 months), but grows fast in temperate season (10-12 months).
基金supported by the National Natural Science Foundation of China(Grant Nos.51434004,U1435205,51774074)the Transformation Project of Major Scientific and Technological Achievements in Shenyang(Grant No.Z17-5-003)
文摘A novel high nitrogen medium-entropy alloy CrCoNiN, which had higher strength and slightly lower ductility than CrCoNi alloy, was successfully manufactured by pressurized metallurgy.The microstructure and corrosion behaviour were investigated by microscopic, electrochemical and spectroscopic methods. The results indicated that nitrogen existed in the form of Cr2N precipitates and uniformly distributed N atoms, and nitrogen alloying significantly refined the grain size. Besides, nitrogen enriched on the outmost surface of passive film and metal/film interface as ammonia （NH3 and NH4^＋） and CrN, respectively. The significant improvement of corrosion resistance of CrCoNiN was attributed to the lower metastahle pitting susceptibility together with thicker, less defective and more compact passive film.
基金funded by the“PORCDIGEST”project(IDI-20140262)funded by the CDTI and the Ministerio de Economía y Competitividad(Spain)support from the pre-doctoral FI grant of the Generalitat de Catalunya(Spain)awarded to Paola López-Colom.
文摘Background:The search for alternatives to antibiotics in pig production has increased the interest in natural resources with antimicrobial properties,such as medium-chain fatty acids(MCFA)as in-feed additives.This study evaluated the potential of a novel blend of MCFA salts(DIC)from distilled coconut oil with a lauric acid content to reduce enteropathogens and control intestinal diseases around weaning.Two experimental disease models were implemented in early-weaned piglets,consisting of two oral challenges:Salmonella Typhimurium(1.2×10~8 CFU)or enterotoxigenic Escherichia coli(ETEC)F4(1.5×10~9 CFU).The parameters assessed were:animal performance,clinical signs,pathogen excretion,intestinal fermentation,immune-inflammatory response,and intestinal morphology.Results:The Salmonella challenge promoted an acute course of diarrhea,with most of the parameters responding to the challenge,whereas the ETEC F4 challenge promoted a mild clinical course.A consistent antipathogenic effect of DIC was observed in both trials in the hindgut,with reductions in Salmonella spp.plate counts in the cecum(P=0.03)on d 8 post-inoculation(PI)(Salmonella trial),and of enterobacteria and total coliform counts in the ileum and colon(P<0.10)on d 8 PI(ETEC F4 trial).When analyzing the entire colonic microbiota(16 S rRNA gene sequencing),this additive tended(P=0.13)to reduce the Firmicutes/Bacteroidetes ratio and enriched Fibrobacteres after the Salmonella challenge.In the ETEC F4 challenge,DIC prompted structural changes in the ecosystem with increases in Dialister,and a trend(P=0.14)to increase the Veillonellaceae family.Other parameters such as the intestinal fermentation products or serum pro-inflammatory mediators were not modified by DIC supplementation,nor were the histological parameters.Only the intraepithelial lymphocyte(IEL)counts were lowered by DIC in animals challenged with Salmonella(P=0.07).With ETEC F4,the IEL counts were higher with DIC on d 8 PI(P=0.08).Conclusions:This study confirms the potential activity of this MCFA salts mixture to reduce intestinal colonization by opportunistic pathogens such as Salmonella or E.coli and its ability to modulate colonic microbiota.These changes could explain to some extent the local immune cell response at the ileal level.
基金supported by the National Key Research and Development Program of China (No. 2017YFA0403804)the National Natural Science Foundation of China (NSFC) (Nos. 51471032 and 51527801)+3 种基金the Fundamental Research Funds for the Central Universities (Nos. 06111020 and 06111040)the State Key Laboratory for Advanced Metals and Materials (Nos. 2016Z-01, 2016Z-12, and 2016Z-19)financial support from the Chinese Scholarship Council (CSC)supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences (No. DE-AC02-06CH11357)
文摘An in situ high-energy X-ray diffraction(HE-XRD) technique was mainly used to investigate the micromechanical behavior of medium-Mn Fe-0.12 C-10.16 Mn-1.87 Al(in wt%) transformation-induced plasticit(TRIP) steel subjected to intercritical annealing at 625℃, 650℃, 675℃ and 700℃ for 1 h. As the intercritical annealing temperature increased, the volume fraction of retained austenite(RA) and ultimate tensilstress(UTS) increased, while the Lüders strain and yield stress(YS) decreased. The incremental workhardening exponent of experimental steel increased with increasing intercritical annealing temperatureThe overall trend of the transformation kinetics of the RA with respect to the true strain followed thsigmoidal shape predicted by the Olson and Cohen(OC) model. Load partitioning occurred among the ferrite, austenite and martensite immediately after entering the yielding stage. Because the stability of thRA decreased with increasing intercritical annealing temperature, the load undertaken by the martensitincreased. The moderate transformation kinetics of the RA and effective load partitioning among constituent phases were found to contribute to a favorable combination of strength and ductility for thimedium-Mn TRIP steel.
基金supported by the National Natural Science Foundation of China(No.81172667 and No.81202203)
文摘Objective To investigate activation of brown adipose tissue （BAT） stimulated by medium-chain triglyceride （MCT）. Methods 30 Male C57BL/6J obese mice induced by fed high fat diet （HFD） were divided into 2 groups, and fed another HFD with 2% MCT or long-chain triglyceride （LCT） respectively for 12 weeks. Body weight, blood biochemical variables, interscapular brown fat tissue （IBAT） mass, expressions of mRNA and protein of beta 3-adrenergic receptors （β3-AR）, uncoupling protein-1 （UCP1）, hormone sensitive lipase （HSL）, protein kinase A （PKA）, and adipose triglyceride lipase （ATGL） in IBAT were measured. Results Significant decrease in body weight and body fat mass was observed in MCT group as compared with LCT group （P〈O.05） after 12 weeks. Greater increases in IBAT mass was observed in MCT group than in LCT group （P〈O.05）. Blood TG, TC, LDL-C in MCT group were decreased significantly, meanwhile blood HDL-C, ratio of HDL-C/LDL-C and norepinephrine were increased markedly. Expressions of mRNA and protein of β3-AR, UCP1, PKA, HSL, ATGL in BAT were greater in MCT group than in LCT group （P〈O.05）. Conclusion Our results suggest that MCT stimulated the activation of BAT, possible via norepinephrine pathway, which might partially contribute to reduction of the body fat mass in obese mice fed high fat diet.
基金Item Sponsored by National Natural Science Foundation of China and Baosteel Co(50674020)
文摘The flow field of molten steel and the interfacial behaviour between molten steel and liquid slag layer in medium-thin slab continuous casting mold with argon gas injection were studied by numerical simulation, in which the effects of nozzle submergence depth and port angle, casting speed, and argon gas flow rate on the flow and the level fluctuation of molten steel were considered. The results show that the molten steel is jetted from the submerged en- try nozzle （SEN） with three ports into the mold and forms three recirculation zones including one upper recireulation zone and two lower recirculation zones. Argon gas injection results in a secondary vortex flow in the upper zone near the nozzle. For a given casting speed and argon gas flow rate, increasing the side port angle and submergence depth of nozzle can effectively restrain the steel/slag interracial fluctuation. Increasing the casting speed would prick up the level fluctuation. For a fixed casting speed, argon gas flow rate has a critical value, the interracial fluctuation with argon gas injection are stronger than the case without argon gas injection when the argon gas flow rate is less than the critical value, but when the argon gas flow rate exceeds the critical value, the level fluctuation is calmer than that without argon gas injection.
基金supported by Foundation for University Key Teacher by the Ministry of Education of China(GG-901-11117-1003)the Research Fund from Jiangsu Province of China(BE2001333).
文摘The effects of the basal and top-dressing nitrogen (N) on N uptake and translocation, N utilization efficiency, grain yieldand quality of medium-gluten winter wheat Yangmai 10 were studied from 2000 to 2002. The main results were as follows.Nitrogen content and nitrogen accumulation in plant at maturity increased with the amount of N application. Grain proteincontent and wet gluten content were significantly correlated with applied N. There was a significantly positive correlationbetween nitrogen accumulation before anthesis (NBA) and basal N fertilizer, and between nitrogen accumulation afteranthesis (NAA) and top-dressing N. N accumulated in grains was significantly correlated to NBA, NAA and N translocationfrom vegetative organs after anthesis (NTVA). NBA was significantly correlated with N application, but NAA and NTVAhad a quadratic curve correlation with applied N. N fertilizer use efficiency (NUE) had a quadratic curve correlation withapplied N, and the NUE was high when basal and top-dressing N was equally applied. For the medium-gluten wheatYangmai 10 under the same N application ratio, there was a N-regulating effect when the N application was less than266.55 kg ha-1, a stagnation of yield and quality when N application ranged from 266.55 to 309.08 kg ha-1, and an excessiveN application when the N application rate was greater than 309.08 kg ha-1. Under the conditions of this experiment, theprecise N application is 220-270 kg ha-1 with basal and top-dressing N equally used when a grain yield of more than 6 750kg ha-1, protein content higher than 12%, wet gluten content more than 30% and NUE greater than 40% could be obtained.
基金Program supported by National Nature Science Foundation of China(51271163)Key Project of Science and Technology of Hebei Province(09215106D)
文摘The flux cored wires with different rare earth oxide additions for hardfacing the workpieces of medium-high carbon steel were developed. The microstrucmre of the hardfacing layer was observed using the optical microscopy. The average dimension of primary austenite grains in hardfacing layer was measured by image analyzer. The primary austenite grain growth activation energy and index were calculated according to Sellars＇s mode and Beck formula, respectively. Moreover, the effect of rare earth oxide on the growth dynamics of primary aus- tenite grain was analyzed, and then discussed with the misfit theory. The experimental results showed that, by adding rare earth oxide, the av- erage dimension of primary austenite grains in hardfacing layer of medium-high carbon steel decreased, and it was the smallest when the ad- dition of rare earth oxide was 5.17 wt.%. Meanwhile, at this rare earth oxide addition, the primary austenite grain growth activating energy in hardfacing layer was the largest, while its index was the smallest. The calculated results indicated that the primary austenite grain could be refined because LaAlO3 as heterogeneous nuclei of γ-Fe was the most effective.
基金sponsorship provided by Innovate UK through the Knowledge Transfer Partnership Programme(KTP010269 Sheffield Hallam University and Tyzack Machine Knives Ltd.)
文摘The microstructure and mechanical properties of NiCrMoV-and NiCrSi-alloyed medium-carbon steels were investigated after multiple tempering. After austenitising, the steels were hardened by oil quenching and subsequently double or triple tempered at temperatures from 250 to 500 °C. The samples were characterised using scanning electron microscopy and X-ray diffraction, while the mechanical properties were evaluated by Vickers hardness testing, V-notched Charpy impact testing and tensile testing. The results showed that the retained austenite was stable up to 400 °C and the applied multiple tempering below this temperature did not lead to a complete decomposition of retained austenite in both steels. It was also found that the microstructure, hardness and impact toughness varied mainly as a function of tempering temperature,regardless of the number of tempering stages. Moreover, the impact toughness of NiCrMoV steel was rather similar after single/triple tempering at different temperatures, while NiCrSi steel exhibited tempered martensite embrittlement after single/double tempering at 400 °C. The observed difference was mainly attributed to the effect of precipitation behaviour due to the effect of alloying additions in the studied steels.
基金sponsored by Key Projects in the National Science&Technology Pillar Program of China(2013BAE07B00)State Natural Science Fund Projects of China(51474142,51671124)+1 种基金Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning(2012)China Postdoctoral Science Foundation(2015M580316)
文摘A new process involving ultra-fast cooling（UFC）and on-line tempering（OLT）was proposed to displace austempering process,which usually implements in a salt/lead bath and brings out serious pollution in the industrial application.The optimization of the new process,involving the evolution of the microstructure of medium-carbon steel during various cooling paths,was studied.The results show that the cooling path affected the final microstructure in terms of the fraction of pearlite,grain size and distribution of cementite in pearlite.Increasing the cooling rate or decreasing the OLT temperature contributes to restraining the transformation from austenite to ferrite,and simultaneously retains more austenite for the transformation of pearlite.It is also noted that bainite was observed in the microstructure at the cooling rate of 45℃/s and the OLT temperature of 500℃.Through either increasing the cooling rate or decreasing the OLT temperature,the distribution of cementite in pearlite is more dispersed and grain is refined.Taking the possibility of industrial applications into account,the optimal process of cooling at 45℃/s followed by OLT at 600℃ after hot rolling was determined,which achieves a microstructure containing nearly full pearlite with an average grain size of approximately 7μm and a homogeneously dispersed distribution of cementite in pearlite.
基金Item Sponsored by National Key Fundamental Research and Development Programme of China (2004CB619104)
文摘The delayed fracture behavior of medium carbon high strength spring steel containing different amounts of boron （0. 000 5%, 0. 001 6 %） was studied using sustained load delayed fracture test. The results show that delayed fracture resistance of boron containing steels is higher than that of conventional steel 60Si2MnA at the same strength level and it increases with the increase of boron eontent from 0. 000 5% to 0. 001 6%. The delayed fracture mode is mainly intergranular in the boron containing steels tempered at 350℃, which indicates that the addition of boron does not change the fracture character. However, the increase of boron content enlarges the size of the crack initia tion area. Further study of phase analysis indicates that most boron is in solid solution, and only a very small quantity of boron is in the M3 （C, B） phase.
基金Supported by Key Projects in the National Science & Technology Pillar Program during the 12th Five-year Plan Period(2011BAD22B04)the National Basic Research Program of China(973 program)(2011CB710800,2011CB200905,2009CB724703)+2 种基金the National Natural Science Foundation of China(21076017)the National High-Tech R & D Program of China(863 Program)(2012AA021404,2012AA021402)the Fundamental Research Funds for the Central Universities(ZY1331)
文摘The non-edible camphor tree seed oil was extracted and catalyzed by immobilized lipase for biodiesel production. The oil yield from camphor tree seeds reached 35.2% of seed weight by twice microwave-assisted extractions. Gas chromatography showed that free fatty acid content in camphor tree seed oil was 1.88%, and the main fatty acids were capric acid(53.4%) and lauric acid(38.7%). With immobilized lipase Candida sp. 99–125as catalyst, several important factors for reaction conditions were examined through orthogonal experiments.The optimum conditions were obtained: water content and enzyme loading were both 15% with a molar ratio of 1:3.5(oil/ethanol), and the process of alcoholysis was in nine steps at 40 °C for 24 h, with agitation at170 r·min-1. As a result, the medium-chain biodiesel yield was 93.5%. The immobilized lipase was stable when it was used repeatedly for 210 h.
基金financially supported by the National Major Science and Technology Project of China (No. 2014ZX07214-002)
文摘An ultrafine-grained(UFG) low-carbon medium-manganese steel was fabricated by the heavily warm rolling(HWR) and subsequent quenching, and the effects of annealing temperatures on microstructure and mechanical properties of the UFG HWRed steel were investigated. The results show that the HWRed steel exhibits simultaneous improvements in strength,uniform elongation and work hardening, which is mainly attributed to the refinement of martensitic microstructures. The HWRed steels comprise only a-phase when annealing at lower temperatures below to 550 °C and at higher temperatures above to 700 °C. Whereas, UFG c-austenite is formed by reverse transformation when the HWRed steel was annealed at intermediate temperatures from 550 to 700 °C and the volume fraction increases with increasing annealing temperatures,consequently resulting in a dramatic increase in ductility of the annealed HWRed steels. It was found that the transformed UFG austenite and ferrite remained ～500 nm and ～800 nm in size when the HWRed steel was annealed at 650 and700 °C for 1 h, respectively, showing an excellent thermal stability. Moreover, the HWRed steel annealed at 650 °C exhibits high strength-ductility combinations with a yield strength of 906 MPa, ultimate tensile strength(UTS) of1011 MPa, total elongation(TEL) of 51% and product of strength and elongation(PSE: UTS 9 TEL) of 52 GPa%. It is believed that these excellent comprehensive mechanical properties are closely associated with the UFG austenite formation by reverse transformation and principally attributed to the transformation-induced plasticity(TRIP) effect.
基金Supported by the China National Science and Technology Major Project(2016ZX05007004,2016ZX05004005)
文摘Based on the analysis of the basic characteristics of medium-and large-sized marine gas fields in Sichuan Basin, combined with the division of major reservoir forming geological units in the marine craton stage and their control on key hydrocarbon accumulation factors, the distribution law of medium-and large-sized marine carbonate gas fields in the basin was examined and the exploration direction was pointed out. Through the analysis of the periodic stretching-uplifting background, it is concluded that five large scale paleo-rifts, three large scale paleo-uplifts, five large scale paleo erosion surfaces were formed in the marine craton stage of Sichuan Basin, and these geological units control the key reservoir forming factors of medium and large sized gas fields:(1) Large-scale paleo-rifts control the distribution of high-quality hydrocarbon generation centers.(2) The margin of large-scale paleo-rifts, high position of paleo-uplifts and paleo erosion surfaces control the distribution of high-quality reservoirs.(3) Large-scale paleo-rifts, paleo-uplifts, paleo erosion surfaces and present tectonic setting jointly control the formation of many types of large and medium-sized traps.(4) Natural gas accumulation is controlled by the inheritance evolution of traps in large geological units. Based on the comparative analysis of the distribution characteristics of medium-and large-sized gas fields and large geological units, it is proposed that the superimposition relationship between single or multiple geological units and the present structure controls the distribution of medium-and large-sized gas fields, and the "three paleo" superimposed area is the most advantageous. According to the above rules, the main exploration fields and directions of medium-and large-sized marine carbonate gas fields in Sichuan Basin include periphery of Deyang-Anyue paleo-rift, eastern margin of Longmenshan paleo-rift, margins of Kaijiang-Liangping oceanic trough and Chengkou-western Hubei oceanic trough, the high part of the subaqueous paleo-uplifts around Central Sichuan, paleo erosion surfaces of the top boundary of Maokou Formation in eastern and southern Sichuan Basin, paleo erosion surfaces of the top boundary of the Leikoupo Formation in central and western Sichuan Basin.
基金Item Sponsored by Program for New Century Excellent Talents in University(NCET-09-0396)State Major Science and Technology Special Project Foundation for High-End Numerical Machine and Basic Manufacturing Equipment(2011ZX04014-052,2012ZX04012-011)
文摘A mathematical model for describing the melting process in the medium-frequency induction furnace was developed.Finite difference method was applied to deal with coupling electromagnetic field and temperature field in the melting process.The magnetic induction,temperature distribution and the phase interface moving characteristic during melting of the furnace burden were calculated.The effects of the direct current and inductive heating frequency on the process were analyzed.The simulation results show that:In the direction of burden radius,magnetic induction decreases from the outside of the burden to the center.Solid/liquid interface moves gradually from the outside of the burden to the center.The movement speed increases when the burden begins to melt.In the direction of the burden height,the distribution of eddy current in the surface is accord with the edge effect of the coil.Solid/liquid interface moves gradually from the center to the two sides.The direct current has a greater effect on the electromagnetic field and temperature field than frequency.
基金the project of " Mechanism for Continental Strong Earthquakes and Their Prediction" , one of the projects in the National Basic Scientific Research and Development Program,grant No.G1998040706.
文摘The Zhangjiakou-Penglai fault zone lies in the northern part of North China Plain and extends along the Zhangjiakou-Huailai-Sanhe-Tianjin-Bohai Sea-Penglai-Yantai-North Huanghai Sea line, it is about 900 km long and some 250-km wide in a northwest direction. The 1679 Sanhe-Pinggu M 8.0 and the 1976 Tangshan M7.8 earthquakes occurred in the fault zone. In this paper an analysis of Gutenberg- Richter’s empirical relation and time process of historic and recent earthquakes along the eastern and western segments of the fault zone separated by the 117°line indicates that they obey a Poison process and, hence, a calculation from it yields a cumulative probability of strong earthquake occurrence along the two segments before 2010, i. e. the probability of M6.0 earthquake occurrence is 0.80 along the eastern segment and the probability of M7. 0 earthquake occurrence is 0.76 along the western segment of the fault zone.
文摘The effect of RE-modifier on the microstructure and mechanical properties of high carbon-medium manganese steel has been investigated in present work.The results showed that the RE-modifier can refine the crystalline grain of high-carbon medium-manganese steel.The shape and distribution of carbides are improved and the columnar grains and phosphide in grain boundary are eliminated.Consequently,the impact toughness of the steel is increased by more than one time,compared with no addition of RE-modifier.
