Based on the definition of R&D pcrformance auditing system, this paper analyzes the characteristics of the system. Then it designs the components of the R&D performance auditing system and the procedure of its estab...Based on the definition of R&D pcrformance auditing system, this paper analyzes the characteristics of the system. Then it designs the components of the R&D performance auditing system and the procedure of its establishment.展开更多
Traditionally governance structures are classified into "hierarchy or market" or "equity or non-equity." However,such classifications may not be effective in characterizing all governance structures of research an...Traditionally governance structures are classified into "hierarchy or market" or "equity or non-equity." However,such classifications may not be effective in characterizing all governance structures of research and development(R D) alliances.Therefore,the first objective of this study is to investigate why there exist different organizational governance structures in managing R D alliances;the second objective of this study is to give strategic advice in choosing appropriate forms with respect to various characteristics of R D alliances.Through the theoretical lens that integrate both transaction cost economics(TCE) and the resource-based view(RBV),a model that focuses on six major factors is developed for determining governance structure choices,namely,technological uncertainty,cultural difference,asset specificity,technology complementarity,appropriability of the individual firm's know-how,and trust.An R D alliance with higher technological uncertainty,larger cultural differences,and greater concerns for protecting an individual's know-how is more likely to adopt non-integrated alliances as the governing structure.An R D alliance with a higher degree of asset-specificity,greater technology complementarity and greater trust among partnering organizations is more likely to adopt integrated alliances as the governing structure;an R D alliance in the face of lower technological uncertainty will tend to adopt integrated alliances.The more aligned the choice of the governance structure with its determinants,the better the R D alliance will perform,and vice versa.展开更多
A high performance 70nm CMOS device has been demonstrated for the first time in the continent, China. Some innovations in techniques are applied to restrain the short channel effect and improve the driving ability, ...A high performance 70nm CMOS device has been demonstrated for the first time in the continent, China. Some innovations in techniques are applied to restrain the short channel effect and improve the driving ability, such as 3nm nitrided oxide, dual poly Si gate electrode, novel super steep retrograde channel doping by heavy ion implantation, ultra shallow S/D extension formed by Ge PAI(Pre Amorphism Implantation) plus LEI(Low Energy Implantation), thin and low resistance Ti SALICIDE by Ge PAI and special cleaning, etc. The shortest channel length of the CMOS device is 70nm. The threshold voltages, G m and off current are 0 28V,490mS·mm -1 and 0 08nA/μm for NMOS and -0 3V,340mS·mm -1 and 0 2nA/μm for PMOS, respectively. Delays of 23 5ps/stage at 1 5V, 17 5ps/stage at 2 0V and 12 5ps/stage at 3V are achieved in the 57 stage unloaded 100nm CMOS ring oscillator circuits.展开更多
Objective To investigate the relationship among serum vitamin D levels, physical performance impairment, and geriatric syndromes in elders with hypertension. Methods According to the concentration of vitamin D levels,...Objective To investigate the relationship among serum vitamin D levels, physical performance impairment, and geriatric syndromes in elders with hypertension. Methods According to the concentration of vitamin D levels, a total of 143 elderly patients with hypertension were classified into vitamin D deficient group (vitamin D 〈 20 ng/mL, n = 94) and vitamin D appropriate group (vitamin D 〉 20 ng/rnL, n = 49). Geriatric syndromes and physical performance were assessed by using comprehensive geriatric assessment (CGA). Correlation among vitamin D levels, geriatric syndromes and physical performance was analyzed. Results No statistical differences were found in various aspects of geriatric syndromes between the two groups (P 〉 0.05). While correlation analysis indicated that vitamin D levels had a positive association with ADL score (r = 0.235, P 〈 0.01) and a negative association with Morse fall scale score (r = 0.238, P 〈 0.01). Patients with deficient vitamin D level had longer time both in the Five Time Sit to Stand Test (5tSTS), (15.765 ± 5.593) and the four-meter walk test [7.440 (5.620, 9.200)], a weaker hand-grip in the grip strength test (28.049 ± 9.522), and a lower Tinetti performance-oriented mobility assessment (Tinetti POMA) [26 (22, 27)] and Balance subscale of the Tinetti performance-oriented mobility assessment (B-POMA) score [ 14 (12, 16)], compared with appropriate vitamin D level [(13.275 ± 3.692); 5.810 (4.728, 7.325)]; (31.989 ± 10.217); [26.5 (25, 28)]; [15 (14, 16), respectively, all P 〈 0.05]. Furthermore, results of logistic regression indicated that vitamin D was significantly associated with 5tSTS (OR = 1.2, 95% CI = 1.050-1.331, P 〈 0.01), Tinetti POMA (OR = 3.7, 95% CI:1.284-10.830, P 〈 0.05) and B-POMA (OR = 0.8, 95% CI:0.643-0.973, P 〈 0.05). Conclusions In elderly hypertensive patients, serum vitamin D deficient level is associated with physical performance impairment. However, no statistical significance was found between vitamin D and geriatric syndromes. Further study is required to investigate possible mechanisms for the association between vitamin D and physical performance.展开更多
This paper examines the performance of an atmospheric general circulation model (AGCM) developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of ...This paper examines the performance of an atmospheric general circulation model (AGCM) developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics (LASG/IAP). It is a spectral model truncated at R42(2.8125°long×1.66°lat) resolution and with nine vertical levels, and referred to as R42L9/LASG hereafter. It is also the new version of atmospheric component model R15L9 of the global ocean-atmosphere-land system (GOALS/LASG). A 40-year simulation in which the model is forced with the climatological monthly mean sea surface temperature is compared with the 40-year (1958-97) U.S. National Center for Environmental Prediction (NGEP) global reanalysis and the 22-year (1979-2000) Xie-Arkin monthly precipitation climatology. The mean DJF and JJA geographical distributions of precipitation, sea level pressure, 500-hPa geopotential height, 850-hPa and 200-hPa zonal wind, and other fields averaged for the last 30-year integration of the R42L9 model are analyzed. Results show that the model reproduces well the observed basic patterns, particularly precipitation over the East Asian region. Comparing the new model with R15L9/LASG, the old version with coarse resolution (nearly 7.5°long×4.5°lat), shows an obvious improvement in the simulation of regional climate, especially precipitation. The weaknesses in simulation and future improvements of the model are also discussed.展开更多
Carbon materials are considered to be one of the most promising anode materials for sodium-ion batteries(SIBs),but the well-ordered graphitic structure limits the intercalation of sodium ions.Besides,the sluggish inte...Carbon materials are considered to be one of the most promising anode materials for sodium-ion batteries(SIBs),but the well-ordered graphitic structure limits the intercalation of sodium ions.Besides,the sluggish intercalation kinetics of sodium ions impedes the rate performance.Thus,the precise structure control of carbon materials is important to improve the battery performance.Herein,a 3D porous hard-soft composite carbon(3DHSC)was prepared using the NaCl as the template and phenolic resin and pitch as carbon precursors.The NaCl template restrains the growth of the graphite crystallite during the carbonization process,resulting in small graphitic domains with expanded interlayer spacing which is favorable for the sodium storage.Moreover,the Na Cl templates help to create abundant mesopores and macropores for fast sodium ion diffusion.The porous structure and the graphite crystalline structure can be precisely controlled by simply adjusting the mass ratio of Na Cl,and thus,the suitable structure can be prepared to reach high capacity and rate performance while keeping a relatively high Coulombic efficiency.Typically,a high reversible capacity(215 mA h g^(-1)at 0.05 A g^(-1)),an excellent rate capability(97 mA h g^(-1)at 5 A g^(-1)),and a high initial Coulombic efficiency(60%)are achieved.展开更多
Germanium(Ge), an alloy-type anode material for lithium-ion batteries(LIBs), possesses many advantages such as high theoretical capacity and decent electrical conductivity. Nevertheless, its application is restricted ...Germanium(Ge), an alloy-type anode material for lithium-ion batteries(LIBs), possesses many advantages such as high theoretical capacity and decent electrical conductivity. Nevertheless, its application is restricted by tremendous volume variation and tardy reaction kinetic during discharge/charge process.In this paper, the Ge/3DPG composites with Ge nanoparticles uniformly dispersed in 3D interconnected porous graphene(3DPG) skeleton are successfully prepared using a template-assisted in-situ reduction method. The unique 3D interconnected porous graphene can not only enhance the electronic conductivity and reaction kinetics of the materials, but also provide sufficient buffer space to effectively mitigate the volume expansion during cycling and strengthen the structural integrity. Moreover, the small-sized Ge nanoparticles in close conjunction with the 3D graphene can boost the surface-controlled reaction of the electrode, which contributes to a fast charge–discharge rate capability. The Ge/3DPG composite with optimized Ge/graphene mass ratio delivers high reversible specific capacity(1102 mAh g^(-1) after 100 cycles at 0.2 C), outstanding rate capability(494 mAh g^(-1) at 5 C), and admirable cycling stability(85.3% of capacity retention after 250 cycles at 0.5 C). This work provides a significant inspiration for the design and fabrication of advanced Ge-based anode materials for next-generation highperformance LIBs.展开更多
Rechargeable microbatteries are important power supplies for microelectronic devices.Two essential targets for rechargeable microbatteries are high output energy and minimal footprint areas.In addition to the developm...Rechargeable microbatteries are important power supplies for microelectronic devices.Two essential targets for rechargeable microbatteries are high output energy and minimal footprint areas.In addition to the development of new high-performance electrode materials,the device configurations of microbatteries also play an important role in enhancing the output energy and miniaturizing the footprint area.To make a clear vision on the design principle of rechargeable microbatteries,we firstly summarize the typical configurations of microbatteries.The advantages of different configurations are thoroughly discussed from the aspects of fabrication technologies and material engineering.Towards the high energy output at a minimal footprint area,a revolutionary design for microbatteries is of great importance.In this perspective,we review the progress of fabricating microbatteries based on the rolled-up nanotechnology,a derivative origami technology.Finally,we discussed the challenges and perspectives in the device design and materials optimization.展开更多
Traditional electrode manufacturing for lithium-ion batteries is well established,reliable,and has already reached high processing speeds and improvements in production costs.For modern electric vehicles,however,the n...Traditional electrode manufacturing for lithium-ion batteries is well established,reliable,and has already reached high processing speeds and improvements in production costs.For modern electric vehicles,however,the need for batteries with high gravimetric and volumetric energy densities at cell level is increasing;and new production concepts are required for this purpose.During the last decade,laser processing of battery materials emerged as a promising processing tool for either improving manufacturing flexibility and product reliability or enhancing battery performances.Laser cutting and welding already reached a high level of maturity and it is obvious that in the near future they will become frequently implemented in battery production lines.This review focuses on laser texturing of electrode materials due to its high potential for significantly enhancing battery performances beyond state-of-the-art.Technical approaches and processing strategies for new electrode architectures and concepts will be presented and discussed with regard to energy and power density requirements.The boost of electrochemical performances due to laser texturing of energy storage materials is currently proven at the laboratory scale.However,promising developments in high-power,ultrafast laser technology may push laser structuring of batteries to the next technical readiness level soon.For demonstration in pilot lines adapted to future cell production,process upscaling regarding footprint area and processing speed are the main issues as well as the economic aspects with regards to CapEx amortization and the benefits resulting from the next generation battery.This review begins with an introduction of the three-dimensional battery and thick film concept,made possible by laser texturing.Laser processing of electrode components,namely current collectors,anodes,and cathodes will be presented.Different types of electrode architectures,such as holes,grids,and lines,were generated;their impact on battery performances are illustrated.The usage of high-energy materials,which are on the threshold of commercialization,is highlighted.Battery performance increase is triggered by controlling lithium-ion diffusion kinetics in liquid electrolyte filled porous electrodes.This review concludes with a discussion of various laser parameter tasks for process upscaling in a new type of extreme manufacturing.展开更多
40K is one of the most important atomic species for ultra-cold atomic physics. Due to the extremely low con- centration (0.012%) of 40K in natural abundance of potassium, most experiments use 4-10% enriched potassiu...40K is one of the most important atomic species for ultra-cold atomic physics. Due to the extremely low con- centration (0.012%) of 40K in natural abundance of potassium, most experiments use 4-10% enriched potassium source, which have greatly suffered from the extremely low annual production and significant price hikes in recent years. Using naturally abundant potassium source, we capture 5.4 × 10 6 cold 40K atoms with the help of a high performance of two-dimensional magneto-optical trap (2D+ MOT), which is almost three orders of magnitude greater than previous results without the 2D+ MOT. The number of the 40K atoms is sufficient for most ultra-cold 40K experiments, and our approach provides an ideal alternative for the field.展开更多
Two-dimensional(2D)InSe and WS2 exhibit promising characteristics for optoelectronic applications.However,they both have poor absorption of visible light due to wide bandgaps:2D InSe has high electron mobility but low...Two-dimensional(2D)InSe and WS2 exhibit promising characteristics for optoelectronic applications.However,they both have poor absorption of visible light due to wide bandgaps:2D InSe has high electron mobility but low hole mobility,while 2D WS2 is on the contrary.We propose a 2D heterostructure composed of their monolayers as a solution to both problems.Our first-principles calculations show that the heterostructure has a type-Ⅱband alignment as expected.Consequently,the bandgap of the heterostructure is reduced to 2.19 eV,which is much smaller than those of the monolayers.The reduction in bandgap leads to a considerable enhancement of the visible-light absorption,such as about fivefold(threefold)increase in comparison to monolayer InSe(WS2)at the wavelength of 490 nm.Meanwhile,the type-Ⅱ band alignment also facilitates the spatial separation of photogenerated electron-hole pairs;i.e.,electrons(holes)reside preferably in the InSe(WS2)layer.As a result,the two layers complement each other in carrier mobilities of the heterostructure:the photogenerated electrons and holes inherit the large mobilities from the InSe and WS2 monolayers,respectively.展开更多
Diesel engines have proven over the years important in terms of efficiency and fuel consumption to power generation ratio. Many research works show the potential of biodiesel as a substitute for conventional gasoil. M...Diesel engines have proven over the years important in terms of efficiency and fuel consumption to power generation ratio. Many research works show the potential of biodiesel as a substitute for conventional gasoil. Mainly, previous and recent researches have focused on experimental investigation of diesel engine performance fuelled by biodiesel. Researches on the mathematical description of diesel engine process running on biodiesel are scarce, and mostly about chemical and thermodynamic description of the combustion process of biodiesel rather than performance studies. This work describes a numerical investigation on the performance analysis of a diesel engine fuelled by palm oil biodiesel. The numerical investigation was made using a semi empirical 0D model based on Wiebe’s and Watson’s model which was implemented via the open access numerical calculation software Scilab. The model was validated first by comparing with experimental pressure and performance data of a one cylinder engine at rated speed and secondly by comparing with a six cylinders engine performance data at various crankshaft rotational speeds. Simulations were then made to analyze the engine performance when running on biodiesel. The calculations were made at constant combustion duration and constant coefficient of excess air. Results showed that the model matches the overall experimental data, such as the power output and peak cylinder pressure. The ignition delay was somehow underestimated by the model for the first experiment, which caused a slight gap on in cylinder pressure curve, whereas it predicted the average ignition delay fairly well for the second set of validation. The simulations of engine performance when running on biodiesel confirmed results obtained in previous experimental researches on biodiesel. The model will be further investigated for engine control when shifting to biodiesel fuel.展开更多
Molybdenum sulfide(MoS_(2))with well-designed porous structure has the potential to be great electrode materials in sodium-ion batteries due to its high theoretical capacity and abundant resource,however,hindered by i...Molybdenum sulfide(MoS_(2))with well-designed porous structure has the potential to be great electrode materials in sodium-ion batteries due to its high theoretical capacity and abundant resource,however,hindered by its intrinsic low conductivity and stability.Herein,MoS_(2) with 3 D macroporous foam structure and high conductivity was obtained through SiO_(2) templates and integrated with carbon paper(3 D FMoS_(2)/CP).It has showed superior specific capacity(225 m A h g^(-1),0.4–3 V)and cycling stability(1000 cycles)at high rate(2000 m A g^(-1)),with a low decay rate(0.033%per cycle)in sodium-ion batteries.The excellent electrochemical performance may originate from its unique integrated structure:3 D MoS_(2) macropores providing high surface area and abundant transfer channels while carbon paper enhancing the conductivity of MoS_(2) and avoiding unnecessary side reactions brought by binder addition.展开更多
In this paper,we theorize about the impacts of human resource management(HRM) practices on enterprises' performance in Abidjan(Cote d'Ivoire).Specifically,we emphasize the correlation between HRM practices and t...In this paper,we theorize about the impacts of human resource management(HRM) practices on enterprises' performance in Abidjan(Cote d'Ivoire).Specifically,we emphasize the correlation between HRM practices and the perceived enterprise performance.A factor analysis of different HRM practices was utilized.The exploratory factor analysis on the HRM practices for managerial employees revealed three HRM dimensions:employee development,feedback systems,and pay/organization.A separate factor analysis for HRM practices for non-managerial employees led to the same conclusions.These three factors resemble those obtained in previous empirical study and discussed in the theoretical HRM literature.Therefore,the relationship among these three HRM dimensions and their relationship with enterprise performance was examined in the present study to facilitate comparison between managerial and non-managerial employees in the Ivorian context.展开更多
In recent years, China has promulgated many laws and regulations of environmental protection, gradually forming an environmental regulation system, and most enterprises are under the dual pressure of environmental pro...In recent years, China has promulgated many laws and regulations of environmental protection, gradually forming an environmental regulation system, and most enterprises are under the dual pressure of environmental protection and business performance. It would be a significant way that enterprises undertake R&D activities for a change. This paper is based on the Shanghai and Shenzhen A-share listed heavy pollution enterprises in 2011-2016, which is based on the review and summary of research results of former researchers, combining with current environmental regulation situation of our country, raising the relevant hypothesis between environmental regulations, R&D investment and business performance against heavy pollution industry. Adopting the method of empirical research, it also built the linear regression model which employs the relevant financial data of heavy-polluting enterprises in China as the statistical research sample. The relationship for heavy-polluting enterprises affected by environmental regulations between environmental protection R&D investment and enterprise business performance was tested. The results show that there is a positive influence on the environmental R&D investment and business performance, and a lag effect upon the R&D investment of enterprises to business performance. Finally, the research results were used to evaluates problems existing in the R&D investment on pollution industry in China as well as business performance and we put forward some suggestions on improving environmental regulation standards and technology innovation consciousness as well as optimizing the structure of R&D investment.展开更多
Objective To improve the creativity and enthusiasm of R&D personnel in R Company.Methods The status quo of the performance assessment of R&D personnel in R Company was studied through questionnaire and intervi...Objective To improve the creativity and enthusiasm of R&D personnel in R Company.Methods The status quo of the performance assessment of R&D personnel in R Company was studied through questionnaire and interview survey.Factor analysis and multiple linear regression method were used to find out the core factors affecting the expectation of employee performance optimization,and the regression equation of employee performance optimization was established.Results and Conclusion R&D personnel in R Company have low satisfaction with the current performance appraisal and strong self-actualization needs,so they expect to optimize the performance appraisal.The objectives and key results(OKR),a management goal-setting system,can make up the deficiencies of R&D personnel’s current performance assessment in R Company,which meets their self-realization needs to a greater extent,thus stimulating their productivity.展开更多
Object classification in high-density 3D point clouds with applications in precision farming is a very challenging area due to high intra-class variances and high degrees of occlusions and overlaps due to self-similar...Object classification in high-density 3D point clouds with applications in precision farming is a very challenging area due to high intra-class variances and high degrees of occlusions and overlaps due to self-similarities and densely packed plant organs, especially in ripe growing stages. Due to these application specific challenges, this contribution gives an experimental evaluation of the performance of local shape descriptors (namely Point-Feature Histogram (PFH), Fast-Point-Feature Histogram (FPFH), Signature of Histograms of Orientations (SHOT), Rotational Projection Statistics (RoPS) and Spin Images) in the classification of 3D points into different types of plant organs. We achieve very good results on four representative scans of a leave, a grape bunch, a grape branch and a flower of between 94 and 99% accuracy in the case of supervised classification with an SVM and between 88 and 96% accuracy using a k-means clustering approach. Additionally, different distance measures and the influence of the number of cluster centres are examined.展开更多
The performance parameters of vapor compression refrigeration units that used the refrigerant R-404A were studied by developing a computer simulation algorithm. The various performance parameters investigated per one ...The performance parameters of vapor compression refrigeration units that used the refrigerant R-404A were studied by developing a computer simulation algorithm. The various performance parameters investigated per one kilowatt of refrigeration capacity, such as the mass flow rate, the compressor power consumption, the condenser heat rejection rate, the compressor exit temperature and the coefficient of performance. Two refrigeration cycles were tested under various evaporating and condensing temperatures: the standard cycle and the ideal cycle with superheating and sub-cooling. The results of the present work reveal that the compressor power variation over the evaporating temperature range from –10℃ to 15℃at Tc = 40℃ is decreased by 38.8% for standard cycle and by 43.8% for ideal cycle. The compressor power variation over the condensing temperature range from 30℃ to 50℃ at Te = 10℃ is increased by 122% for standard cycle and by 54.5% for ideal cycle. On the other hand, the COP for the ideal cycle with 5℃ superheating and sub-cooling is approximately 25% higher than that of the standard cycle at Te = 10℃ and Tc = 40℃ for the refrigerant R-404A.展开更多
文摘Based on the definition of R&D pcrformance auditing system, this paper analyzes the characteristics of the system. Then it designs the components of the R&D performance auditing system and the procedure of its establishment.
基金The Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Traditionally governance structures are classified into "hierarchy or market" or "equity or non-equity." However,such classifications may not be effective in characterizing all governance structures of research and development(R D) alliances.Therefore,the first objective of this study is to investigate why there exist different organizational governance structures in managing R D alliances;the second objective of this study is to give strategic advice in choosing appropriate forms with respect to various characteristics of R D alliances.Through the theoretical lens that integrate both transaction cost economics(TCE) and the resource-based view(RBV),a model that focuses on six major factors is developed for determining governance structure choices,namely,technological uncertainty,cultural difference,asset specificity,technology complementarity,appropriability of the individual firm's know-how,and trust.An R D alliance with higher technological uncertainty,larger cultural differences,and greater concerns for protecting an individual's know-how is more likely to adopt non-integrated alliances as the governing structure.An R D alliance with a higher degree of asset-specificity,greater technology complementarity and greater trust among partnering organizations is more likely to adopt integrated alliances as the governing structure;an R D alliance in the face of lower technological uncertainty will tend to adopt integrated alliances.The more aligned the choice of the governance structure with its determinants,the better the R D alliance will perform,and vice versa.
文摘A high performance 70nm CMOS device has been demonstrated for the first time in the continent, China. Some innovations in techniques are applied to restrain the short channel effect and improve the driving ability, such as 3nm nitrided oxide, dual poly Si gate electrode, novel super steep retrograde channel doping by heavy ion implantation, ultra shallow S/D extension formed by Ge PAI(Pre Amorphism Implantation) plus LEI(Low Energy Implantation), thin and low resistance Ti SALICIDE by Ge PAI and special cleaning, etc. The shortest channel length of the CMOS device is 70nm. The threshold voltages, G m and off current are 0 28V,490mS·mm -1 and 0 08nA/μm for NMOS and -0 3V,340mS·mm -1 and 0 2nA/μm for PMOS, respectively. Delays of 23 5ps/stage at 1 5V, 17 5ps/stage at 2 0V and 12 5ps/stage at 3V are achieved in the 57 stage unloaded 100nm CMOS ring oscillator circuits.
文摘Objective To investigate the relationship among serum vitamin D levels, physical performance impairment, and geriatric syndromes in elders with hypertension. Methods According to the concentration of vitamin D levels, a total of 143 elderly patients with hypertension were classified into vitamin D deficient group (vitamin D 〈 20 ng/mL, n = 94) and vitamin D appropriate group (vitamin D 〉 20 ng/rnL, n = 49). Geriatric syndromes and physical performance were assessed by using comprehensive geriatric assessment (CGA). Correlation among vitamin D levels, geriatric syndromes and physical performance was analyzed. Results No statistical differences were found in various aspects of geriatric syndromes between the two groups (P 〉 0.05). While correlation analysis indicated that vitamin D levels had a positive association with ADL score (r = 0.235, P 〈 0.01) and a negative association with Morse fall scale score (r = 0.238, P 〈 0.01). Patients with deficient vitamin D level had longer time both in the Five Time Sit to Stand Test (5tSTS), (15.765 ± 5.593) and the four-meter walk test [7.440 (5.620, 9.200)], a weaker hand-grip in the grip strength test (28.049 ± 9.522), and a lower Tinetti performance-oriented mobility assessment (Tinetti POMA) [26 (22, 27)] and Balance subscale of the Tinetti performance-oriented mobility assessment (B-POMA) score [ 14 (12, 16)], compared with appropriate vitamin D level [(13.275 ± 3.692); 5.810 (4.728, 7.325)]; (31.989 ± 10.217); [26.5 (25, 28)]; [15 (14, 16), respectively, all P 〈 0.05]. Furthermore, results of logistic regression indicated that vitamin D was significantly associated with 5tSTS (OR = 1.2, 95% CI = 1.050-1.331, P 〈 0.01), Tinetti POMA (OR = 3.7, 95% CI:1.284-10.830, P 〈 0.05) and B-POMA (OR = 0.8, 95% CI:0.643-0.973, P 〈 0.05). Conclusions In elderly hypertensive patients, serum vitamin D deficient level is associated with physical performance impairment. However, no statistical significance was found between vitamin D and geriatric syndromes. Further study is required to investigate possible mechanisms for the association between vitamin D and physical performance.
文摘This paper examines the performance of an atmospheric general circulation model (AGCM) developed at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics (LASG/IAP). It is a spectral model truncated at R42(2.8125°long×1.66°lat) resolution and with nine vertical levels, and referred to as R42L9/LASG hereafter. It is also the new version of atmospheric component model R15L9 of the global ocean-atmosphere-land system (GOALS/LASG). A 40-year simulation in which the model is forced with the climatological monthly mean sea surface temperature is compared with the 40-year (1958-97) U.S. National Center for Environmental Prediction (NGEP) global reanalysis and the 22-year (1979-2000) Xie-Arkin monthly precipitation climatology. The mean DJF and JJA geographical distributions of precipitation, sea level pressure, 500-hPa geopotential height, 850-hPa and 200-hPa zonal wind, and other fields averaged for the last 30-year integration of the R42L9 model are analyzed. Results show that the model reproduces well the observed basic patterns, particularly precipitation over the East Asian region. Comparing the new model with R15L9/LASG, the old version with coarse resolution (nearly 7.5°long×4.5°lat), shows an obvious improvement in the simulation of regional climate, especially precipitation. The weaknesses in simulation and future improvements of the model are also discussed.
基金supported by the Guangdong Natural Science Funds for Distinguished Young Scholar (2017B030306006)the National Natural Science Foundation of China (Nos. 51772164, U1601206 and U1710256)+2 种基金the National Key Basic Research Program of China (2014CB932400)the Shenzhen Technical Plan Project (Nos. KQJSCX20160226191136, JCYJ20150529164918734 and JCYJ20170412171630020)the Shenzhen Environmental Science and New Energy Technology Engineering Laboratory (No. SDRC [2016]172)
文摘Carbon materials are considered to be one of the most promising anode materials for sodium-ion batteries(SIBs),but the well-ordered graphitic structure limits the intercalation of sodium ions.Besides,the sluggish intercalation kinetics of sodium ions impedes the rate performance.Thus,the precise structure control of carbon materials is important to improve the battery performance.Herein,a 3D porous hard-soft composite carbon(3DHSC)was prepared using the NaCl as the template and phenolic resin and pitch as carbon precursors.The NaCl template restrains the growth of the graphite crystallite during the carbonization process,resulting in small graphitic domains with expanded interlayer spacing which is favorable for the sodium storage.Moreover,the Na Cl templates help to create abundant mesopores and macropores for fast sodium ion diffusion.The porous structure and the graphite crystalline structure can be precisely controlled by simply adjusting the mass ratio of Na Cl,and thus,the suitable structure can be prepared to reach high capacity and rate performance while keeping a relatively high Coulombic efficiency.Typically,a high reversible capacity(215 mA h g^(-1)at 0.05 A g^(-1)),an excellent rate capability(97 mA h g^(-1)at 5 A g^(-1)),and a high initial Coulombic efficiency(60%)are achieved.
基金financially supported by the National Natural Science Foundation of China (21875091 and 51672114)the Shanghai Municipal Education Commission (QD2019008)。
文摘Germanium(Ge), an alloy-type anode material for lithium-ion batteries(LIBs), possesses many advantages such as high theoretical capacity and decent electrical conductivity. Nevertheless, its application is restricted by tremendous volume variation and tardy reaction kinetic during discharge/charge process.In this paper, the Ge/3DPG composites with Ge nanoparticles uniformly dispersed in 3D interconnected porous graphene(3DPG) skeleton are successfully prepared using a template-assisted in-situ reduction method. The unique 3D interconnected porous graphene can not only enhance the electronic conductivity and reaction kinetics of the materials, but also provide sufficient buffer space to effectively mitigate the volume expansion during cycling and strengthen the structural integrity. Moreover, the small-sized Ge nanoparticles in close conjunction with the 3D graphene can boost the surface-controlled reaction of the electrode, which contributes to a fast charge–discharge rate capability. The Ge/3DPG composite with optimized Ge/graphene mass ratio delivers high reversible specific capacity(1102 mAh g^(-1) after 100 cycles at 0.2 C), outstanding rate capability(494 mAh g^(-1) at 5 C), and admirable cycling stability(85.3% of capacity retention after 250 cycles at 0.5 C). This work provides a significant inspiration for the design and fabrication of advanced Ge-based anode materials for next-generation highperformance LIBs.
基金the support and funding from China Scholarship Council(CSC)financial support by the Leibniz Program of the German Research Foundation(SCHM 1298/26-1)。
文摘Rechargeable microbatteries are important power supplies for microelectronic devices.Two essential targets for rechargeable microbatteries are high output energy and minimal footprint areas.In addition to the development of new high-performance electrode materials,the device configurations of microbatteries also play an important role in enhancing the output energy and miniaturizing the footprint area.To make a clear vision on the design principle of rechargeable microbatteries,we firstly summarize the typical configurations of microbatteries.The advantages of different configurations are thoroughly discussed from the aspects of fabrication technologies and material engineering.Towards the high energy output at a minimal footprint area,a revolutionary design for microbatteries is of great importance.In this perspective,we review the progress of fabricating microbatteries based on the rolled-up nanotechnology,a derivative origami technology.Finally,we discussed the challenges and perspectives in the device design and materials optimization.
基金The research to anode material development received funding from the German Research Foundation(DFG,project No.392322200)the development of cathode materials and upscaling strategies was funded by the Federal Ministry of Education and Research(Project NextGen-3DBat,03XP0198F).
文摘Traditional electrode manufacturing for lithium-ion batteries is well established,reliable,and has already reached high processing speeds and improvements in production costs.For modern electric vehicles,however,the need for batteries with high gravimetric and volumetric energy densities at cell level is increasing;and new production concepts are required for this purpose.During the last decade,laser processing of battery materials emerged as a promising processing tool for either improving manufacturing flexibility and product reliability or enhancing battery performances.Laser cutting and welding already reached a high level of maturity and it is obvious that in the near future they will become frequently implemented in battery production lines.This review focuses on laser texturing of electrode materials due to its high potential for significantly enhancing battery performances beyond state-of-the-art.Technical approaches and processing strategies for new electrode architectures and concepts will be presented and discussed with regard to energy and power density requirements.The boost of electrochemical performances due to laser texturing of energy storage materials is currently proven at the laboratory scale.However,promising developments in high-power,ultrafast laser technology may push laser structuring of batteries to the next technical readiness level soon.For demonstration in pilot lines adapted to future cell production,process upscaling regarding footprint area and processing speed are the main issues as well as the economic aspects with regards to CapEx amortization and the benefits resulting from the next generation battery.This review begins with an introduction of the three-dimensional battery and thick film concept,made possible by laser texturing.Laser processing of electrode components,namely current collectors,anodes,and cathodes will be presented.Different types of electrode architectures,such as holes,grids,and lines,were generated;their impact on battery performances are illustrated.The usage of high-energy materials,which are on the threshold of commercialization,is highlighted.Battery performance increase is triggered by controlling lithium-ion diffusion kinetics in liquid electrolyte filled porous electrodes.This review concludes with a discussion of various laser parameter tasks for process upscaling in a new type of extreme manufacturing.
基金Supported by the National Key Research and Development Program of China under Grant Nos 2016YFA0300600 and2016YFA0301500the National Natural Science Foundation of China under Grant Nos 11474347,61227902 and 61775232
文摘40K is one of the most important atomic species for ultra-cold atomic physics. Due to the extremely low con- centration (0.012%) of 40K in natural abundance of potassium, most experiments use 4-10% enriched potassium source, which have greatly suffered from the extremely low annual production and significant price hikes in recent years. Using naturally abundant potassium source, we capture 5.4 × 10 6 cold 40K atoms with the help of a high performance of two-dimensional magneto-optical trap (2D+ MOT), which is almost three orders of magnitude greater than previous results without the 2D+ MOT. The number of the 40K atoms is sufficient for most ultra-cold 40K experiments, and our approach provides an ideal alternative for the field.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11404013,11474012,11364030,61622406,61571415,51502283 and 11605003the National Key Research and Development Program of China under Grant No2017YFA0206303the MOST of China,and the 2018 Graduate Research Program of Beijing Technology and Business University
文摘Two-dimensional(2D)InSe and WS2 exhibit promising characteristics for optoelectronic applications.However,they both have poor absorption of visible light due to wide bandgaps:2D InSe has high electron mobility but low hole mobility,while 2D WS2 is on the contrary.We propose a 2D heterostructure composed of their monolayers as a solution to both problems.Our first-principles calculations show that the heterostructure has a type-Ⅱband alignment as expected.Consequently,the bandgap of the heterostructure is reduced to 2.19 eV,which is much smaller than those of the monolayers.The reduction in bandgap leads to a considerable enhancement of the visible-light absorption,such as about fivefold(threefold)increase in comparison to monolayer InSe(WS2)at the wavelength of 490 nm.Meanwhile,the type-Ⅱ band alignment also facilitates the spatial separation of photogenerated electron-hole pairs;i.e.,electrons(holes)reside preferably in the InSe(WS2)layer.As a result,the two layers complement each other in carrier mobilities of the heterostructure:the photogenerated electrons and holes inherit the large mobilities from the InSe and WS2 monolayers,respectively.
文摘Diesel engines have proven over the years important in terms of efficiency and fuel consumption to power generation ratio. Many research works show the potential of biodiesel as a substitute for conventional gasoil. Mainly, previous and recent researches have focused on experimental investigation of diesel engine performance fuelled by biodiesel. Researches on the mathematical description of diesel engine process running on biodiesel are scarce, and mostly about chemical and thermodynamic description of the combustion process of biodiesel rather than performance studies. This work describes a numerical investigation on the performance analysis of a diesel engine fuelled by palm oil biodiesel. The numerical investigation was made using a semi empirical 0D model based on Wiebe’s and Watson’s model which was implemented via the open access numerical calculation software Scilab. The model was validated first by comparing with experimental pressure and performance data of a one cylinder engine at rated speed and secondly by comparing with a six cylinders engine performance data at various crankshaft rotational speeds. Simulations were then made to analyze the engine performance when running on biodiesel. The calculations were made at constant combustion duration and constant coefficient of excess air. Results showed that the model matches the overall experimental data, such as the power output and peak cylinder pressure. The ignition delay was somehow underestimated by the model for the first experiment, which caused a slight gap on in cylinder pressure curve, whereas it predicted the average ignition delay fairly well for the second set of validation. The simulations of engine performance when running on biodiesel confirmed results obtained in previous experimental researches on biodiesel. The model will be further investigated for engine control when shifting to biodiesel fuel.
基金supported financially by the National Key R&D Program of China(No.2016YFA0204100,2016YFA0200200)the National Natural Science Foundation of China(No.21890753,21988101,21905035)+1 种基金the Danish company Haldor Tops?e A/S,Liaoning Revitalization Talents Program(XLYC1907093)the Liaoning Natural Science Foundation(20180510043)。
文摘Molybdenum sulfide(MoS_(2))with well-designed porous structure has the potential to be great electrode materials in sodium-ion batteries due to its high theoretical capacity and abundant resource,however,hindered by its intrinsic low conductivity and stability.Herein,MoS_(2) with 3 D macroporous foam structure and high conductivity was obtained through SiO_(2) templates and integrated with carbon paper(3 D FMoS_(2)/CP).It has showed superior specific capacity(225 m A h g^(-1),0.4–3 V)and cycling stability(1000 cycles)at high rate(2000 m A g^(-1)),with a low decay rate(0.033%per cycle)in sodium-ion batteries.The excellent electrochemical performance may originate from its unique integrated structure:3 D MoS_(2) macropores providing high surface area and abundant transfer channels while carbon paper enhancing the conductivity of MoS_(2) and avoiding unnecessary side reactions brought by binder addition.
文摘In this paper,we theorize about the impacts of human resource management(HRM) practices on enterprises' performance in Abidjan(Cote d'Ivoire).Specifically,we emphasize the correlation between HRM practices and the perceived enterprise performance.A factor analysis of different HRM practices was utilized.The exploratory factor analysis on the HRM practices for managerial employees revealed three HRM dimensions:employee development,feedback systems,and pay/organization.A separate factor analysis for HRM practices for non-managerial employees led to the same conclusions.These three factors resemble those obtained in previous empirical study and discussed in the theoretical HRM literature.Therefore,the relationship among these three HRM dimensions and their relationship with enterprise performance was examined in the present study to facilitate comparison between managerial and non-managerial employees in the Ivorian context.
基金supported by Jiangsu University Philosophical and Social Science Research Projects (Grant No. 2014SJB4442014)
文摘In recent years, China has promulgated many laws and regulations of environmental protection, gradually forming an environmental regulation system, and most enterprises are under the dual pressure of environmental protection and business performance. It would be a significant way that enterprises undertake R&D activities for a change. This paper is based on the Shanghai and Shenzhen A-share listed heavy pollution enterprises in 2011-2016, which is based on the review and summary of research results of former researchers, combining with current environmental regulation situation of our country, raising the relevant hypothesis between environmental regulations, R&D investment and business performance against heavy pollution industry. Adopting the method of empirical research, it also built the linear regression model which employs the relevant financial data of heavy-polluting enterprises in China as the statistical research sample. The relationship for heavy-polluting enterprises affected by environmental regulations between environmental protection R&D investment and enterprise business performance was tested. The results show that there is a positive influence on the environmental R&D investment and business performance, and a lag effect upon the R&D investment of enterprises to business performance. Finally, the research results were used to evaluates problems existing in the R&D investment on pollution industry in China as well as business performance and we put forward some suggestions on improving environmental regulation standards and technology innovation consciousness as well as optimizing the structure of R&D investment.
文摘Objective To improve the creativity and enthusiasm of R&D personnel in R Company.Methods The status quo of the performance assessment of R&D personnel in R Company was studied through questionnaire and interview survey.Factor analysis and multiple linear regression method were used to find out the core factors affecting the expectation of employee performance optimization,and the regression equation of employee performance optimization was established.Results and Conclusion R&D personnel in R Company have low satisfaction with the current performance appraisal and strong self-actualization needs,so they expect to optimize the performance appraisal.The objectives and key results(OKR),a management goal-setting system,can make up the deficiencies of R&D personnel’s current performance assessment in R Company,which meets their self-realization needs to a greater extent,thus stimulating their productivity.
基金the project“Automated Evaluation and Comparison of Grapevine Genotypes by means of Grape Cluster Architecture”which is supported by the Deutsche Forschungsgemeinschaft(funding code:STE 806/2-1).
文摘Object classification in high-density 3D point clouds with applications in precision farming is a very challenging area due to high intra-class variances and high degrees of occlusions and overlaps due to self-similarities and densely packed plant organs, especially in ripe growing stages. Due to these application specific challenges, this contribution gives an experimental evaluation of the performance of local shape descriptors (namely Point-Feature Histogram (PFH), Fast-Point-Feature Histogram (FPFH), Signature of Histograms of Orientations (SHOT), Rotational Projection Statistics (RoPS) and Spin Images) in the classification of 3D points into different types of plant organs. We achieve very good results on four representative scans of a leave, a grape bunch, a grape branch and a flower of between 94 and 99% accuracy in the case of supervised classification with an SVM and between 88 and 96% accuracy using a k-means clustering approach. Additionally, different distance measures and the influence of the number of cluster centres are examined.
文摘The performance parameters of vapor compression refrigeration units that used the refrigerant R-404A were studied by developing a computer simulation algorithm. The various performance parameters investigated per one kilowatt of refrigeration capacity, such as the mass flow rate, the compressor power consumption, the condenser heat rejection rate, the compressor exit temperature and the coefficient of performance. Two refrigeration cycles were tested under various evaporating and condensing temperatures: the standard cycle and the ideal cycle with superheating and sub-cooling. The results of the present work reveal that the compressor power variation over the evaporating temperature range from –10℃ to 15℃at Tc = 40℃ is decreased by 38.8% for standard cycle and by 43.8% for ideal cycle. The compressor power variation over the condensing temperature range from 30℃ to 50℃ at Te = 10℃ is increased by 122% for standard cycle and by 54.5% for ideal cycle. On the other hand, the COP for the ideal cycle with 5℃ superheating and sub-cooling is approximately 25% higher than that of the standard cycle at Te = 10℃ and Tc = 40℃ for the refrigerant R-404A.