School-based universal screening for behavioral/emotional risk is a necessary first step to providing services in an educational setting for students with emotional and behavioral disorders (EBDs). Psychometric proper...School-based universal screening for behavioral/emotional risk is a necessary first step to providing services in an educational setting for students with emotional and behavioral disorders (EBDs). Psychometric properties are critical to making decisions about choosing a screening instrument. The purpose of the present study was to examine the psychometric properties of the student risk screening scale for internalizing and externalizing behaviors (SRSS-IE). Participants included 3145 students and their teachers. Item-level analyses of the current sample supported the retention of all items. The internal consistency of the SRSS items ranged from 0.83 to 0.85. Convergent validity between the SRSS-IE and a well-established screening tool, the strength and difficulties questionnaire (SDQ), was found for the total score (r = 0.70). Additionally, the results of this study demonstrate strong social validity, suggesting the SRSS-IE to be a useful and functional screening tool. We conclude that the SRSS-IE is a valid and reliable instrument for assessing the level of emotional and behavioral difficulties among elementary students.展开更多
BACKGROUND Pelvic fractures(PF)with concomitant injuries are on the rise due to an increase of high-energy trauma.Increase of the elderly population with age related comorbidities further complicates the management.Ab...BACKGROUND Pelvic fractures(PF)with concomitant injuries are on the rise due to an increase of high-energy trauma.Increase of the elderly population with age related comorbidities further complicates the management.Abdominal organ injuries are kindred with PF due to the proximity to pelvic bones.Presence of contrast blush(CB)on computed tomography in patients with PF is considered a sign of active bleeding,however,its clinical significance and association with outcomes is debatable.AIM To analyze polytrauma patients with PF with a focus on the geriatric population,co-injuries and the value of contrast blush.METHODS This retrospective cohort study included 558 patients with PF admitted to level 1 trauma center(01/2017-01/2023).Analyzed variables included:Age,sex,mechanism of injury(MOI),injury severity score(ISS),Glasgow coma scale(GCS),abbreviated injury scale(AIS),co-injuries,transfusion requirements,pelvic angiography,embolization,laparotomy,orthopedic pelvic surgery,intensive care unit and hospital lengths of stay,discharge disposition and mortality.The study compared geriatric and non-geriatric patients,patients with and without CB and abdominal co-injuries.Propensity score matching was implemented in comparison groups.RESULTS PF comprised 4%of all trauma admissions.89 patients had CB.286(52%)patients had concomitant injuries including 93(17%)patients with abdominal co-injuries.Geriatric patients compared to non-geriatric had more falls as MOI,lower ISS and AIS pelvis,higher GCS,less abdominal co-injuries,similar CB and angio-embolization rates,less orthopedic pelvic surgeries,shorter lengths of stay and higher mortality.After propensity matching,orthopedic pelvic surgery rates remained lower(8%vs 19%,P<0.001),hospital length of stay shorter,and mortality higher(13%vs 4%,P<0.001)in geriatric patients.Out of 89 patients with CB,45(51%)were embolized.After propensity matching,patients with CB compared to without CB had more pelvic angiography(71%vs 12%,P<0.001),higher embolization rates(64%vs 22%,P=0.02)and comparable mortality.CONCLUSION Half of the patients with PF had concomitant co-injuries,including abdominal co-injuries in 17%.Similarly injured geriatric patients had higher mortality.Half of the patients with CB required an embolization.展开更多
With the development of globalization, more and more companies are under global operation. What coming with it, on one hand is chance and opportunity; on the other hand is risk and uncertainty. This paper aims to spec...With the development of globalization, more and more companies are under global operation. What coming with it, on one hand is chance and opportunity; on the other hand is risk and uncertainty. This paper aims to specify the potential and current risks and uncertainty that may be met in international logistics, then seeks some practical methods to dodge and solve them.展开更多
A physical isolation system based on PCI (peripheral component interconnect),embedded with intelligence card technology, strong identity authentication technology and securityaudit, etc., is introduced. The system can...A physical isolation system based on PCI (peripheral component interconnect),embedded with intelligence card technology, strong identity authentication technology and securityaudit, etc., is introduced. The system can physically isolate the internaland external networks. Thehardware of the system, including PCI interface control circuits, network interface circuits andlogic control circuits, is designed to automatically adapt its operation speed and mode to thenetwork and securely isolate the internal and external networks; the software of the system,including the security strategy management module, the security audit module, the database recordexchanging module, the file exchanging module and the mail exchanging module, is designed toefficiently exchange and manage the data transference between the internal and external networks.Also the driver of the system is implemented with Windows driver development kits (DDK) based onNetwork Driver Interface Specification (NDIS). The prototype ofthe system developed has beenemployed in the Police Fire Protection Bureau of Hubei Province, which performs consistently andefficiently. The technological cruxes discussed have practical values for related subjects.展开更多
Accurate chemical shifts of hydrogen atoms in CH groups are difficult to obtain. To solve this problem, relative chemical shifts are introduced. Internal and external standard methods were used to measure the chemical...Accurate chemical shifts of hydrogen atoms in CH groups are difficult to obtain. To solve this problem, relative chemical shifts are introduced. Internal and external standard methods were used to measure the chemical shifts in a whole-concentration of N-methylacetamide- water system. Determination of the chemical shifts of hydrogen atoms, especially those of CH groups, according to the two methods yielded significant differences. Relative chemical shifts were proven to be independent of the reference and may be applied to other systems.展开更多
Extensive studies on nonlinear dynamics of gear systems with internal excitation or external excitation respectively have been carried out. However, the nonlinear characteristics of gear systems under combined interna...Extensive studies on nonlinear dynamics of gear systems with internal excitation or external excitation respectively have been carried out. However, the nonlinear characteristics of gear systems under combined internal and external excitations are scarcely investigated. An eight-degree-of-freedom(8-DOF) nonlinear spur gear-rotor-bearing model, which contains backlash, transmission error, eccentricity, gravity and input/output torque, is established, and the coupled lateral-torsional vibration characteristics are studied. Based on the equations of motion, the coupled spur gear-rotor-bearing system(SGRBS) is investigated using the Runge-Kutta numerical method, and the effects of rotational speed, error fluctuation and load fluctuation on the dynamic responses are explored. The results show that a diverse range of nonlinear dynamic characteristics such as periodic motion, quasi-periodic motion, chaotic behaviors and impacts exhibited in the system are strongly attributed to the interaction between internal and external excitations. Significantly, the changing rotational speed could effectively control the vibration of the system. Vibration level increases with the increasing error fluctuation. Whereas the load fluctuation has an influence on the nonlinear dynamic characteristics and the increasing excitation force amplitude makes the vibration amplitude increase, the chaotic motion may be restricted. The proposed model and numerical results can be used for diagnosis of faults and vibration control of practical SGRBS.展开更多
Internal and external wall surface temperatures (Tws) in April, August and December in Kunming, a city in low latitude plateau, were investigated. Results showed that the Tws in April were of the highest among the thr...Internal and external wall surface temperatures (Tws) in April, August and December in Kunming, a city in low latitude plateau, were investigated. Results showed that the Tws in April were of the highest among the three, followed by August and December. The Tws differences among walls with different orientation were higher in April and December when the weather tends to be sunny, and lower in August with more cloudy days in the time. In April and August, Tws of E-wall was the highest, followed by S- and N-wall. But in December Tws of S-wall might be sometimes higher than E one. Diurnal range of internal Tws was usually smaller than that of the external, with also a time lag for the occurrence of its maximum and minimum. The results can serve as a basis for further research on building microclimate and urban architecture designs. It also gives suggestions for similar studies in other areas.展开更多
Globe control valve is widely used in chemical, petroleum and hydraulic industries, and its throttling feature is achieved by the adopting of valve plug. However, very limited information is available in literature re...Globe control valve is widely used in chemical, petroleum and hydraulic industries, and its throttling feature is achieved by the adopting of valve plug. However, very limited information is available in literature regarding the influence of valve plug on the internal and external features in globe control valves. Thus the effect of valve plug is studied by CFD and experiment in this paper. It is obtained from external features that the pressure drop between upstream and downstream pressure-sampling position increases exponentially with flow rate. And for small valve opening, the increment of pressure drop decreases with the increase of cone angle(β). However, with the increase of valve opening, the effect of cone angle diminishes significantly. It is also found that the cone angle has little effect on flow coefficient(Cv) when the valve opening is larger than 70%. But for the cases less than 70%, Cv curve varies from an arc to a straight line. The variation of valve performance is caused by the change of internal flow. The results of internal flow show that cone angle has negligible effect on flow properties for the cases of valve opening larger than 70%. However, when valve opening is smaller than 70%, the pressure drop of orifice decreases with the increase of β, making the reduction in value and scope of the high speed zone around the conical surface of valve plug, and then results in a decreasing intensity of adjacent downstream vortex. Meanwhile, it is concluded from the results that the increase of cone angle will be beneficial for the anti-cavitation and anti-erosion of globe control valve. This paper focuses on the internal and external features of globe control valve that caused by the variation of cone angle, arriving at some results beneficial for the design and usage of globe control valve.展开更多
The research on consumers' purchase intention for 3G handsets has important theoretical and practical value. This research puts forward four key factors which influence consumers' purchase intention based on t...The research on consumers' purchase intention for 3G handsets has important theoretical and practical value. This research puts forward four key factors which influence consumers' purchase intention based on the cue utilization theory, situational theory and social impact theory, then it establishes the study model for consumers' purchase intention of 3G handsets. Based on the result of the questionnaire survey and empirical analysis, the study shows that social influence is the most prominent factor in purchase intention. Moreover, as different from results of previous studies, the situational influence factors have no significant impact on purchase intention in the 3G handsets market. The results of the model provides a forceful evidence for operators' and handset manufacturers' decision-making of 3G handsets design and marketing strategies, and it will improve their social impact.展开更多
The start-up of external circulationadded internal circulation(IC) reactor was finished in 26 d, 32 d fewer than that of IC reactor. To evaluate the influence of the added external circulation on the development of gr...The start-up of external circulationadded internal circulation(IC) reactor was finished in 26 d, 32 d fewer than that of IC reactor. To evaluate the influence of the added external circulation on the development of granular sludge, the characteristics of the granular sludge taken from the two tested laboratory-scale reactors during start-up were studied. The results show that the added external circulation can enhance biomass granulation, accelerate granule development and improve sludge characteristics. At the end of start-up, the granular size of sludge in external circulation-added IC reactor greatly increases with a size distribution much better than that of sludge in IC reactor. The granular sludge originated from external circulationadded IC reactor contains more extracellular polymers and has a greater settling velocity than that from IC reactor. Methanogenic activity of the granular sludge from the external circulationadded IC reactor started 26 d ago reaches 358.23mL·g -1 ·d -1 , 1.66 and 1.20 times as great as that of the sludge from the IC reactor started 26 d and 58 d ago respectively.展开更多
Scratch test and friction test were performed to evaluate the internal and external interface behaviors of TiAISiN coating, respectively. The critical compressive and shearing stress of coating failure during scratch ...Scratch test and friction test were performed to evaluate the internal and external interface behaviors of TiAISiN coating, respectively. The critical compressive and shearing stress of coating failure during scratch test were calculated and the values are 30.84 MPa and 4.98 MPa respectively. The average friction coefficients of TiAISiN coat- ing against 2Crl2Ni4Mo3VNbN steel are 0.70 (sliding speed 50 m/rain), 0.63 (sliding speed 100 m/min), and 0.81 (sliding speed 150 m/min). The elements diffusion was analyzed by EDS. A1 and Si element of coating material dif- fuse to the steel disc, except Ti element. The oxidation decreases with the increase of sliding speed, but the adhesion increases with the increase of sliding speed. More A1 element diffuses to the steel disc at the high sliding speed, but the diffusion of Si element keeps almost constant at dlfferent sliding speeds.展开更多
In order to solve the problem of using new nozzle is proposed in fire rescue robot. middle or low water pressure to form fine water mist, a Existing water mist nozzles are basically used for high pressure and in large...In order to solve the problem of using new nozzle is proposed in fire rescue robot. middle or low water pressure to form fine water mist, a Existing water mist nozzles are basically used for high pressure and in large size, complex structure and poor low pressure atomization effect in comparison with requirement of snake-like fire rescue robots. On the basis of comprehensive typical spray noz- zles, a direct spiral double helix converging nozzle (DSDHCN) is proposed, which has the advanta- ges of small volume, light weight, simple structure, and convenient installation. To make the spray nozzle have good performance, and meet the requirements of more efficient fire extinguishing, a nu- merical study is carried out to analyze the internal and external full flow field of nozzle. A gas-liquid two-phase flow is applied to simulate the external full flow field of nozzle with VOF model in fluent software. The simulation results show the real situation of water flow out of the atomization nozzle and the water jet trajectory. Some simulations about middle or low water pressure direct spiral double he- lix converging optimized nozzle have been done in 30bar pressure. The simulation results show that the optimized nozzle structure not only makes the spray droplets have a good cone angle, but also have a sufficient axial velocity,which proves the structure rationality of the proposed optimized nozzle.展开更多
Arctic sea ice extent has been declining in recent decades. There is ongoing debate on the contribution of natural internal variability to recent and future Arctic sea ice changes. In this study, we contrast the trend...Arctic sea ice extent has been declining in recent decades. There is ongoing debate on the contribution of natural internal variability to recent and future Arctic sea ice changes. In this study, we contrast the trends in the forced and unforced simulations of carefully selected global climate models with the extended observed Arctic sea ice records. The results suggest that the natural variability explains no more than 42.3% of the observed September sea ice extent trend during 35 a(1979–2013) satellite observations, which is comparable to the results of the observed sea ice record extended back to 1953(61 a, less than 48.5% natural variability). This reinforces the evidence that anthropogenic forcing plays a substantial role in the observed decline of September Arctic sea ice in recent decades. The magnitude of both positive and negative trends induced by the natural variability in the unforced simulations is slightly enlarged in the context of increasing greenhouse gases in the 21st century.However, the ratio between the realizations of positive and negative trends change has remained steady, which enforces the standpoint that external forcing will remain the principal determiner of the decreasing Arctic sea ice extent trend in the future.展开更多
A problem of the air pollution control in China is getting to know a regional contribution rate of internal and external source of PM2.5. In this paper,Set Pair Analysis( SPA) method is proposed to calculate the con...A problem of the air pollution control in China is getting to know a regional contribution rate of internal and external source of PM2.5. In this paper,Set Pair Analysis( SPA) method is proposed to calculate the contribution rate of PM2.5in Dongguan City. Due to geographic,meteorological factors and the low concentration of air pollutants in Qingxi area,the PM2.5in this place is mainly contributed by the regional transport of air pollutants from other inside areas of Dongguan,and less affected by the outside of Dongguan. So the concentration of PM2.5in Qingxi area can reflect the Dongguan's basic background concentration of PM2.5. On the basis of the basic background concentration,firstly the concentration of each pollutant components is divided into the internal part and the mixed part. Secondly using the source apportionment samples of five monitoring sites in Dongguan we can respectively construct a sample set A and an evaluation set B. Thirdly the SPA is operated onto the mixed part in terms of set B.At last the connection degree between the concentration of each pollutant components and external source and internal source will be calculated,that is the contribution rate. The research reveals that the contribution rate of internal source and external source of PM2.5in Dongguan City is 83%and 17% respectively,which roughly met expectations. This method is simple and effective and it can provide a reference for the government taking reduction measures to control PM2.5pollutants emission.展开更多
In this paper, highly active Ziegler-Natta catalysts of MgCl_2 supported TiCl_4 for synthesis ofpolyolefins, using di-n-butyl phthalate (DNBP) as internal donor and diphenyl dimethoxyl silane(DPDMS) as external donor,...In this paper, highly active Ziegler-Natta catalysts of MgCl_2 supported TiCl_4 for synthesis ofpolyolefins, using di-n-butyl phthalate (DNBP) as internal donor and diphenyl dimethoxyl silane(DPDMS) as external donor, have been prepared. The conditions controlling the treatment ofsupport were studied. The interactions of various components present in the catalysts and theirinfluences on catalytic performance were investigated. It is found that by using DNBP and DPDMSas internal and external donors together the polymer products with higher isotactic index can beobtained. Plausible structure model and mechanism were proposed.展开更多
Primary erythema limb pain is a very rare disease,and its pathogenesis is not clear.Usually,the pain symptoms of patients exist for a long time,which seriously affect the daily life of patients and increase the econom...Primary erythema limb pain is a very rare disease,and its pathogenesis is not clear.Usually,the pain symptoms of patients exist for a long time,which seriously affect the daily life of patients and increase the economic burden of patients.Professor Liu Guobin,who has been engaged in the diagnosis and treatment of peripheral vascular diseases for nearly 30 years,believes that heat-toxin and blood stasis collaterals are closely related to the disease,and emphasizes the principle of heat-toxin and evil qi causing the disease.It is emphasized that clearing heat and detoxification,promoting blood circulation and dispersing blood stasis are the main treatment principles.This paper selects a typical case to describe Professor Liu's clinical experience in the treatment of primary erythema limb pain by oral and external use of traditional Chinese medicine,so as to provide an effective method of traditional Chinese medicine for the treatment of primary erythema limb pain.展开更多
China Pakistan Economic Corridor (CPEC) is dreamed to be the game changer not only for China and Pakistan but other 50 regional, Middle East, Central Asian Republics, and European countries too. It is one of its kin...China Pakistan Economic Corridor (CPEC) is dreamed to be the game changer not only for China and Pakistan but other 50 regional, Middle East, Central Asian Republics, and European countries too. It is one of its kind a huge project with billion US$ investment by China. Since its inception, the internal controversies and disputes in Pakistan on the sharing of benefits as well as interests and concerns of the regional and international players are posing threats to it. The review article aims to investigate and analyze the strengths and weakness and opportunities and threats (SWOT) for CPEC. To analyze the qualitative data, a computer based software program ATLAS.ti was used by employing multiple methods like discourse, hermeneutics, and heuristic by Moustakas. The schematic model of the theoretical framework elaborates the association and impact between and on the dependent, independent, and mediating variables of the study. It was found that if the security, political support, internal and external threats, coordination and cooperation and involvement of stakeholders are properly addressed, the CPEC will bear the fruits.展开更多
The stability of a class of delayed cellular neural networks (DCNN) with or without noise perturbation is studied. After presenting a simple and easily checkable condition for the global exponential stability of a d...The stability of a class of delayed cellular neural networks (DCNN) with or without noise perturbation is studied. After presenting a simple and easily checkable condition for the global exponential stability of a deterministic system, we further investigate the case with noise perturbation. When DCNN is perturbed by external noise, the system is globally stable. An important fact is that, when the system is perturbed by internal noise, it is globally exponentially stable only if the total noise strength is within a certain bound. This is significant since the stochastic resonance phenomena have been found to exist in many nonlinear systems.展开更多
This study aimed to evaluate the external and internal fluxes of nutrients of an urban eutrophic reservoir (lbirit6 reservoir, SE-Brazil). External loads were estimated in the tributaries (Pintados and Ibirit6 cre...This study aimed to evaluate the external and internal fluxes of nutrients of an urban eutrophic reservoir (lbirit6 reservoir, SE-Brazil). External loads were estimated in the tributaries (Pintados and Ibirit6 creeks) through nutrient concentrations and discharge measurements. Using Fick's law, internal loads were estimated in the reservoir from fluxes across sediment-water interface from nutrient concentration gradients between the pore water and the water. The Ibirit6 creek (urban sewage recipient) contributes with 72%-47% of ammonium (NH4^+) and 100%-8% of SRP (soluble reactive phosphorus) of the total quantity entering the reservoir, whereas the Pintados creek (oil refinery effluent recipient) contributions are 20%-19% and 44%-100%, respectively. Despite the high external loads (130 and 2.2 ton-yr^-1 of NH4+ and SRP, respectively), internal loads (average flux of 120 and 2 mg·cm^-2yr^-1, respectively) correspond to 25% of the total external loads which may sustain a high productivity in the reservoir for a long time even if the external loads are controlled. The stocks of ammonium and SRP of the interstitial water (100 cm of sediment) would be released to the water in six years and five months, respectively, The release time would be extremely larger (〉 3,000 years) considering the stocks of total N and bioavailable P.展开更多
The CMC International and Domestic Trade Division under the China National Machinery Import & Export Corporation has, in accordance with the CMC’s strategic goals, worked out the following business guidelines: in...The CMC International and Domestic Trade Division under the China National Machinery Import & Export Corporation has, in accordance with the CMC’s strategic goals, worked out the following business guidelines: internal trade is the basis of external trade, and external trade is a supplementary to internal trade; domestic and overseas markets and resources should be used effectively, and internal trade and external trade should be coordinated and handled in a unified way. The Division’s business concept is to conduct trade-dominated business backed by展开更多
文摘School-based universal screening for behavioral/emotional risk is a necessary first step to providing services in an educational setting for students with emotional and behavioral disorders (EBDs). Psychometric properties are critical to making decisions about choosing a screening instrument. The purpose of the present study was to examine the psychometric properties of the student risk screening scale for internalizing and externalizing behaviors (SRSS-IE). Participants included 3145 students and their teachers. Item-level analyses of the current sample supported the retention of all items. The internal consistency of the SRSS items ranged from 0.83 to 0.85. Convergent validity between the SRSS-IE and a well-established screening tool, the strength and difficulties questionnaire (SDQ), was found for the total score (r = 0.70). Additionally, the results of this study demonstrate strong social validity, suggesting the SRSS-IE to be a useful and functional screening tool. We conclude that the SRSS-IE is a valid and reliable instrument for assessing the level of emotional and behavioral difficulties among elementary students.
文摘BACKGROUND Pelvic fractures(PF)with concomitant injuries are on the rise due to an increase of high-energy trauma.Increase of the elderly population with age related comorbidities further complicates the management.Abdominal organ injuries are kindred with PF due to the proximity to pelvic bones.Presence of contrast blush(CB)on computed tomography in patients with PF is considered a sign of active bleeding,however,its clinical significance and association with outcomes is debatable.AIM To analyze polytrauma patients with PF with a focus on the geriatric population,co-injuries and the value of contrast blush.METHODS This retrospective cohort study included 558 patients with PF admitted to level 1 trauma center(01/2017-01/2023).Analyzed variables included:Age,sex,mechanism of injury(MOI),injury severity score(ISS),Glasgow coma scale(GCS),abbreviated injury scale(AIS),co-injuries,transfusion requirements,pelvic angiography,embolization,laparotomy,orthopedic pelvic surgery,intensive care unit and hospital lengths of stay,discharge disposition and mortality.The study compared geriatric and non-geriatric patients,patients with and without CB and abdominal co-injuries.Propensity score matching was implemented in comparison groups.RESULTS PF comprised 4%of all trauma admissions.89 patients had CB.286(52%)patients had concomitant injuries including 93(17%)patients with abdominal co-injuries.Geriatric patients compared to non-geriatric had more falls as MOI,lower ISS and AIS pelvis,higher GCS,less abdominal co-injuries,similar CB and angio-embolization rates,less orthopedic pelvic surgeries,shorter lengths of stay and higher mortality.After propensity matching,orthopedic pelvic surgery rates remained lower(8%vs 19%,P<0.001),hospital length of stay shorter,and mortality higher(13%vs 4%,P<0.001)in geriatric patients.Out of 89 patients with CB,45(51%)were embolized.After propensity matching,patients with CB compared to without CB had more pelvic angiography(71%vs 12%,P<0.001),higher embolization rates(64%vs 22%,P=0.02)and comparable mortality.CONCLUSION Half of the patients with PF had concomitant co-injuries,including abdominal co-injuries in 17%.Similarly injured geriatric patients had higher mortality.Half of the patients with CB required an embolization.
文摘With the development of globalization, more and more companies are under global operation. What coming with it, on one hand is chance and opportunity; on the other hand is risk and uncertainty. This paper aims to specify the potential and current risks and uncertainty that may be met in international logistics, then seeks some practical methods to dodge and solve them.
文摘A physical isolation system based on PCI (peripheral component interconnect),embedded with intelligence card technology, strong identity authentication technology and securityaudit, etc., is introduced. The system can physically isolate the internaland external networks. Thehardware of the system, including PCI interface control circuits, network interface circuits andlogic control circuits, is designed to automatically adapt its operation speed and mode to thenetwork and securely isolate the internal and external networks; the software of the system,including the security strategy management module, the security audit module, the database recordexchanging module, the file exchanging module and the mail exchanging module, is designed toefficiently exchange and manage the data transference between the internal and external networks.Also the driver of the system is implemented with Windows driver development kits (DDK) based onNetwork Driver Interface Specification (NDIS). The prototype ofthe system developed has beenemployed in the Police Fire Protection Bureau of Hubei Province, which performs consistently andefficiently. The technological cruxes discussed have practical values for related subjects.
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China (No.20903026), the Talents Introduction Foundation for Universities of Guangdong Province (No.2011), Scientific Research Foundation of the Natural Science Foundation of Guangdong Province, China (No.S2011010002483), and Science and Technology Planning Project of Guangzhou (No.2013J4100071).
文摘Accurate chemical shifts of hydrogen atoms in CH groups are difficult to obtain. To solve this problem, relative chemical shifts are introduced. Internal and external standard methods were used to measure the chemical shifts in a whole-concentration of N-methylacetamide- water system. Determination of the chemical shifts of hydrogen atoms, especially those of CH groups, according to the two methods yielded significant differences. Relative chemical shifts were proven to be independent of the reference and may be applied to other systems.
基金Supported by National Natural Science Foundation of China(Grant No.51475084)
文摘Extensive studies on nonlinear dynamics of gear systems with internal excitation or external excitation respectively have been carried out. However, the nonlinear characteristics of gear systems under combined internal and external excitations are scarcely investigated. An eight-degree-of-freedom(8-DOF) nonlinear spur gear-rotor-bearing model, which contains backlash, transmission error, eccentricity, gravity and input/output torque, is established, and the coupled lateral-torsional vibration characteristics are studied. Based on the equations of motion, the coupled spur gear-rotor-bearing system(SGRBS) is investigated using the Runge-Kutta numerical method, and the effects of rotational speed, error fluctuation and load fluctuation on the dynamic responses are explored. The results show that a diverse range of nonlinear dynamic characteristics such as periodic motion, quasi-periodic motion, chaotic behaviors and impacts exhibited in the system are strongly attributed to the interaction between internal and external excitations. Significantly, the changing rotational speed could effectively control the vibration of the system. Vibration level increases with the increasing error fluctuation. Whereas the load fluctuation has an influence on the nonlinear dynamic characteristics and the increasing excitation force amplitude makes the vibration amplitude increase, the chaotic motion may be restricted. The proposed model and numerical results can be used for diagnosis of faults and vibration control of practical SGRBS.
基金Key project from the Natural Science Foundation of China (59836250)
文摘Internal and external wall surface temperatures (Tws) in April, August and December in Kunming, a city in low latitude plateau, were investigated. Results showed that the Tws in April were of the highest among the three, followed by August and December. The Tws differences among walls with different orientation were higher in April and December when the weather tends to be sunny, and lower in August with more cloudy days in the time. In April and August, Tws of E-wall was the highest, followed by S- and N-wall. But in December Tws of S-wall might be sometimes higher than E one. Diurnal range of internal Tws was usually smaller than that of the external, with also a time lag for the occurrence of its maximum and minimum. The results can serve as a basis for further research on building microclimate and urban architecture designs. It also gives suggestions for similar studies in other areas.
基金Supported by National Natural Science Foundation of China(Grant Nos.51406184,21276241)Science Foundation of Zhejiang Sci-Tech University of China(Grant No.14022005-Y)
文摘Globe control valve is widely used in chemical, petroleum and hydraulic industries, and its throttling feature is achieved by the adopting of valve plug. However, very limited information is available in literature regarding the influence of valve plug on the internal and external features in globe control valves. Thus the effect of valve plug is studied by CFD and experiment in this paper. It is obtained from external features that the pressure drop between upstream and downstream pressure-sampling position increases exponentially with flow rate. And for small valve opening, the increment of pressure drop decreases with the increase of cone angle(β). However, with the increase of valve opening, the effect of cone angle diminishes significantly. It is also found that the cone angle has little effect on flow coefficient(Cv) when the valve opening is larger than 70%. But for the cases less than 70%, Cv curve varies from an arc to a straight line. The variation of valve performance is caused by the change of internal flow. The results of internal flow show that cone angle has negligible effect on flow properties for the cases of valve opening larger than 70%. However, when valve opening is smaller than 70%, the pressure drop of orifice decreases with the increase of β, making the reduction in value and scope of the high speed zone around the conical surface of valve plug, and then results in a decreasing intensity of adjacent downstream vortex. Meanwhile, it is concluded from the results that the increase of cone angle will be beneficial for the anti-cavitation and anti-erosion of globe control valve. This paper focuses on the internal and external features of globe control valve that caused by the variation of cone angle, arriving at some results beneficial for the design and usage of globe control valve.
基金supported by China Fundamental Research Funds for the Central Universities under Grant No.2011RC1006Humanities and Social Sciences Planning Fund Project, Ministry of Education of the PRC under Grant No.11YJA630081
文摘The research on consumers' purchase intention for 3G handsets has important theoretical and practical value. This research puts forward four key factors which influence consumers' purchase intention based on the cue utilization theory, situational theory and social impact theory, then it establishes the study model for consumers' purchase intention of 3G handsets. Based on the result of the questionnaire survey and empirical analysis, the study shows that social influence is the most prominent factor in purchase intention. Moreover, as different from results of previous studies, the situational influence factors have no significant impact on purchase intention in the 3G handsets market. The results of the model provides a forceful evidence for operators' and handset manufacturers' decision-making of 3G handsets design and marketing strategies, and it will improve their social impact.
文摘The start-up of external circulationadded internal circulation(IC) reactor was finished in 26 d, 32 d fewer than that of IC reactor. To evaluate the influence of the added external circulation on the development of granular sludge, the characteristics of the granular sludge taken from the two tested laboratory-scale reactors during start-up were studied. The results show that the added external circulation can enhance biomass granulation, accelerate granule development and improve sludge characteristics. At the end of start-up, the granular size of sludge in external circulation-added IC reactor greatly increases with a size distribution much better than that of sludge in IC reactor. The granular sludge originated from external circulationadded IC reactor contains more extracellular polymers and has a greater settling velocity than that from IC reactor. Methanogenic activity of the granular sludge from the external circulationadded IC reactor started 26 d ago reaches 358.23mL·g -1 ·d -1 , 1.66 and 1.20 times as great as that of the sludge from the IC reactor started 26 d and 58 d ago respectively.
基金Supported by China Postdoctoral Science Foundation(No. 20110490380 and No. 20110490383)Dongfang Turbine Co, Ltd (No. 2011GZ011)State Key Laboratory of Tribology, Tsinghua University (No. SKLT10A01)
文摘Scratch test and friction test were performed to evaluate the internal and external interface behaviors of TiAISiN coating, respectively. The critical compressive and shearing stress of coating failure during scratch test were calculated and the values are 30.84 MPa and 4.98 MPa respectively. The average friction coefficients of TiAISiN coat- ing against 2Crl2Ni4Mo3VNbN steel are 0.70 (sliding speed 50 m/rain), 0.63 (sliding speed 100 m/min), and 0.81 (sliding speed 150 m/min). The elements diffusion was analyzed by EDS. A1 and Si element of coating material dif- fuse to the steel disc, except Ti element. The oxidation decreases with the increase of sliding speed, but the adhesion increases with the increase of sliding speed. More A1 element diffuses to the steel disc at the high sliding speed, but the diffusion of Si element keeps almost constant at dlfferent sliding speeds.
基金Supported by the National Natural Science Foundation of China(No.61105086)Self-Planned Task(SKLRS-2010-MS-12)of State Key Laboratory of Robotics and System(HIT)Hubei Province Natural Science Foundation(No.2010CDB03405)
文摘In order to solve the problem of using new nozzle is proposed in fire rescue robot. middle or low water pressure to form fine water mist, a Existing water mist nozzles are basically used for high pressure and in large size, complex structure and poor low pressure atomization effect in comparison with requirement of snake-like fire rescue robots. On the basis of comprehensive typical spray noz- zles, a direct spiral double helix converging nozzle (DSDHCN) is proposed, which has the advanta- ges of small volume, light weight, simple structure, and convenient installation. To make the spray nozzle have good performance, and meet the requirements of more efficient fire extinguishing, a nu- merical study is carried out to analyze the internal and external full flow field of nozzle. A gas-liquid two-phase flow is applied to simulate the external full flow field of nozzle with VOF model in fluent software. The simulation results show the real situation of water flow out of the atomization nozzle and the water jet trajectory. Some simulations about middle or low water pressure direct spiral double he- lix converging optimized nozzle have been done in 30bar pressure. The simulation results show that the optimized nozzle structure not only makes the spray droplets have a good cone angle, but also have a sufficient axial velocity,which proves the structure rationality of the proposed optimized nozzle.
基金The National Natural Science Foundation of China under contract Nos 41305097 and 41176169
文摘Arctic sea ice extent has been declining in recent decades. There is ongoing debate on the contribution of natural internal variability to recent and future Arctic sea ice changes. In this study, we contrast the trends in the forced and unforced simulations of carefully selected global climate models with the extended observed Arctic sea ice records. The results suggest that the natural variability explains no more than 42.3% of the observed September sea ice extent trend during 35 a(1979–2013) satellite observations, which is comparable to the results of the observed sea ice record extended back to 1953(61 a, less than 48.5% natural variability). This reinforces the evidence that anthropogenic forcing plays a substantial role in the observed decline of September Arctic sea ice in recent decades. The magnitude of both positive and negative trends induced by the natural variability in the unforced simulations is slightly enlarged in the context of increasing greenhouse gases in the 21st century.However, the ratio between the realizations of positive and negative trends change has remained steady, which enforces the standpoint that external forcing will remain the principal determiner of the decreasing Arctic sea ice extent trend in the future.
基金Supported by National Natural Science Foundation of China(71171089)Research for PM_(2.5) Contamination Characteristics and Prevention and Control Countermeasures in Dongguan City(Dongcaidan[2013]222)
文摘A problem of the air pollution control in China is getting to know a regional contribution rate of internal and external source of PM2.5. In this paper,Set Pair Analysis( SPA) method is proposed to calculate the contribution rate of PM2.5in Dongguan City. Due to geographic,meteorological factors and the low concentration of air pollutants in Qingxi area,the PM2.5in this place is mainly contributed by the regional transport of air pollutants from other inside areas of Dongguan,and less affected by the outside of Dongguan. So the concentration of PM2.5in Qingxi area can reflect the Dongguan's basic background concentration of PM2.5. On the basis of the basic background concentration,firstly the concentration of each pollutant components is divided into the internal part and the mixed part. Secondly using the source apportionment samples of five monitoring sites in Dongguan we can respectively construct a sample set A and an evaluation set B. Thirdly the SPA is operated onto the mixed part in terms of set B.At last the connection degree between the concentration of each pollutant components and external source and internal source will be calculated,that is the contribution rate. The research reveals that the contribution rate of internal source and external source of PM2.5in Dongguan City is 83%and 17% respectively,which roughly met expectations. This method is simple and effective and it can provide a reference for the government taking reduction measures to control PM2.5pollutants emission.
基金This work was supported by the National Natural Science Foundation of China
文摘In this paper, highly active Ziegler-Natta catalysts of MgCl_2 supported TiCl_4 for synthesis ofpolyolefins, using di-n-butyl phthalate (DNBP) as internal donor and diphenyl dimethoxyl silane(DPDMS) as external donor, have been prepared. The conditions controlling the treatment ofsupport were studied. The interactions of various components present in the catalysts and theirinfluences on catalytic performance were investigated. It is found that by using DNBP and DPDMSas internal and external donors together the polymer products with higher isotactic index can beobtained. Plausible structure model and mechanism were proposed.
基金Youth programs of national natural science foundation of China(No.81804095)Funding project of Shanghai innovation center of TCM health service(No.ZYJKFW201701002
文摘Primary erythema limb pain is a very rare disease,and its pathogenesis is not clear.Usually,the pain symptoms of patients exist for a long time,which seriously affect the daily life of patients and increase the economic burden of patients.Professor Liu Guobin,who has been engaged in the diagnosis and treatment of peripheral vascular diseases for nearly 30 years,believes that heat-toxin and blood stasis collaterals are closely related to the disease,and emphasizes the principle of heat-toxin and evil qi causing the disease.It is emphasized that clearing heat and detoxification,promoting blood circulation and dispersing blood stasis are the main treatment principles.This paper selects a typical case to describe Professor Liu's clinical experience in the treatment of primary erythema limb pain by oral and external use of traditional Chinese medicine,so as to provide an effective method of traditional Chinese medicine for the treatment of primary erythema limb pain.
文摘China Pakistan Economic Corridor (CPEC) is dreamed to be the game changer not only for China and Pakistan but other 50 regional, Middle East, Central Asian Republics, and European countries too. It is one of its kind a huge project with billion US$ investment by China. Since its inception, the internal controversies and disputes in Pakistan on the sharing of benefits as well as interests and concerns of the regional and international players are posing threats to it. The review article aims to investigate and analyze the strengths and weakness and opportunities and threats (SWOT) for CPEC. To analyze the qualitative data, a computer based software program ATLAS.ti was used by employing multiple methods like discourse, hermeneutics, and heuristic by Moustakas. The schematic model of the theoretical framework elaborates the association and impact between and on the dependent, independent, and mediating variables of the study. It was found that if the security, political support, internal and external threats, coordination and cooperation and involvement of stakeholders are properly addressed, the CPEC will bear the fruits.
基金the National Natural Science Foundation of China(No.10771155)the Special Foundation for the Authors of National Excellent Doctoral Dissertations of China(FANEDD)
文摘The stability of a class of delayed cellular neural networks (DCNN) with or without noise perturbation is studied. After presenting a simple and easily checkable condition for the global exponential stability of a deterministic system, we further investigate the case with noise perturbation. When DCNN is perturbed by external noise, the system is globally stable. An important fact is that, when the system is perturbed by internal noise, it is globally exponentially stable only if the total noise strength is within a certain bound. This is significant since the stochastic resonance phenomena have been found to exist in many nonlinear systems.
文摘This study aimed to evaluate the external and internal fluxes of nutrients of an urban eutrophic reservoir (lbirit6 reservoir, SE-Brazil). External loads were estimated in the tributaries (Pintados and Ibirit6 creeks) through nutrient concentrations and discharge measurements. Using Fick's law, internal loads were estimated in the reservoir from fluxes across sediment-water interface from nutrient concentration gradients between the pore water and the water. The Ibirit6 creek (urban sewage recipient) contributes with 72%-47% of ammonium (NH4^+) and 100%-8% of SRP (soluble reactive phosphorus) of the total quantity entering the reservoir, whereas the Pintados creek (oil refinery effluent recipient) contributions are 20%-19% and 44%-100%, respectively. Despite the high external loads (130 and 2.2 ton-yr^-1 of NH4+ and SRP, respectively), internal loads (average flux of 120 and 2 mg·cm^-2yr^-1, respectively) correspond to 25% of the total external loads which may sustain a high productivity in the reservoir for a long time even if the external loads are controlled. The stocks of ammonium and SRP of the interstitial water (100 cm of sediment) would be released to the water in six years and five months, respectively, The release time would be extremely larger (〉 3,000 years) considering the stocks of total N and bioavailable P.
文摘The CMC International and Domestic Trade Division under the China National Machinery Import & Export Corporation has, in accordance with the CMC’s strategic goals, worked out the following business guidelines: internal trade is the basis of external trade, and external trade is a supplementary to internal trade; domestic and overseas markets and resources should be used effectively, and internal trade and external trade should be coordinated and handled in a unified way. The Division’s business concept is to conduct trade-dominated business backed by