In the structure of double-nut ball-screw mechanism(BSM),the contact angle of the ball-screw determines the relative positional relationship between the balls and the screw as well as the nut.The contact angle is rela...In the structure of double-nut ball-screw mechanism(BSM),the contact angle of the ball-screw determines the relative positional relationship between the balls and the screw as well as the nut.The contact angle is related to geometrical parameters of the ball,the screw and the nut,which are also affected by the running status and the preload of the BSM.Considering the effect of the gy-roscopic moment on the ball in the raceway,the dynamic model of the ball in space is established under different speeds and different preloads of the BSM.By simulation of the dynamic model of the ball in space,the changing regularity of the contact angle,the helix angle,the drag torque and the mechanical efficiency of the BSM can be obtained under different speeds and different preloads.The results show that there is a nonlinear gradient relationship between contact angle,helix angle,the drag torque,the mechanical efficiency and the speeds of the ball-screw under different preloads.The contact angle is the key factor to affect the drag torque of the BSM.Through the analysis,it is found that establishing the ball dynamic model in space can better study the precision degradation law of the ball screw.展开更多
碳交易市场是实现“双碳”目标的重要途径,丰富的碳金融衍生品有助于增加碳市场活性,可以更好地发挥发现价格和风险管理功能。本文借鉴欧洲碳排放权交易体系中的碳期货期权产品,设计了我国的以碳排放配额为标的碳期权合约,并选择BSM模...碳交易市场是实现“双碳”目标的重要途径,丰富的碳金融衍生品有助于增加碳市场活性,可以更好地发挥发现价格和风险管理功能。本文借鉴欧洲碳排放权交易体系中的碳期货期权产品,设计了我国的以碳排放配额为标的碳期权合约,并选择BSM模型作为碳期权的基础定价模型,描述碳价波动率与碳价之间的变化过程。研究发现,全国碳交易市场是非有效市场,具有反持久性特点,全国碳排放配额收益率具有明显的条件异方差特征,且波动具有显著的持续性。基于此,应加快完善碳市场建设,积极开展碳金融创新实践,加强碳交易市场国际合作。The carbon trading market is an important way to achieve the goal of “double carbon”. Rich carbon financial derivatives can help to increase the activity of the carbon market and better play the role of price discovery and risk management. Based on the carbon futures option products in the European carbon emission trading system, this paper designs a carbon option contract with carbon emission quota as the target in China, and chooses BSM model as the basic pricing model of carbon options to describe the changing process between carbon price volatility and carbon price. It is found that the national carbon trading market is inefficient and anti-persistent, and the national carbon emission quota yield has obvious conditional heteroscedasticity characteristics, and the fluctuation has obvious persistence. Based on this, we should speed up the improvement of carbon market construction, actively carry out carbon financial innovation practice, and strengthen international cooperation in carbon trading market.展开更多
通过总结所有IaaS(infrastructure as a service)云服务定价的方法,明确了pay-per-use和subscription是目前业界普遍采用的两种定价方法,分析了IaaS云服务定价影响因素,并把IaaS云计算服务的五大基础参数(初始投资、合同期限、资源折旧...通过总结所有IaaS(infrastructure as a service)云服务定价的方法,明确了pay-per-use和subscription是目前业界普遍采用的两种定价方法,分析了IaaS云服务定价影响因素,并把IaaS云计算服务的五大基础参数(初始投资、合同期限、资源折旧、服务质量和资源年限)映射到BSM模型中,利用复利摩尔定律和BSM模型公式计算出IaaS云服务在两种定价方法(pay-per-use和subscription)下相对应的价格范围,并分析了两种定价方法的适应范围,更好地解决了现阶段对于IaaS云服务定价中只有云计算服务提供商单边定价的弊端,并从云计算服务提供商和用户两者的角度提供了对于IaaS服务价格的衡量标准。展开更多
造纸污水具有处理量大、有机物污染负荷高的特点,但是对其处理过程中温室气体的大量排放长期以来关注不足。以国际公认的BSM1平台为基础,采用Benchmark simulation model No.1(BSM1)标准数据,根据微生物生长动力学及物料平衡关系,从污...造纸污水具有处理量大、有机物污染负荷高的特点,但是对其处理过程中温室气体的大量排放长期以来关注不足。以国际公认的BSM1平台为基础,采用Benchmark simulation model No.1(BSM1)标准数据,根据微生物生长动力学及物料平衡关系,从污水生化处理工艺的四个方面,建立了温室气体排放计算模型,实现了污水生化处理过程中温室气体排放的动态计算。研究结果表明,污水生化处理过程中的总温室气体排放量为0.419 kg CO_2/m^3污水,其中具有高温室效应潜势的N_2O对温室气体的总排放的影响高达13%,应引起重视。展开更多
Understanding functional relations among plant traits and their modulation by growing conditions is imperative in designing selection strategies for breeding programs. This study assessed trait relationships among 196...Understanding functional relations among plant traits and their modulation by growing conditions is imperative in designing selection strategies for breeding programs. This study assessed trait relationships among 196 common bean genotypes exposed to stresses for drought and field infestation of bean fly or bean stem maggot(BSM). The study was carried out at two locations and data was analyzed with linear correlation, path coefficient and genotype × trait biplot analyses. Multiple trait data related to mechanisms of drought and bean fly tolerance were collected on 196 genotypes grown under i) water deficit at mid-pod fill, or ii) unprotected against bean fly; iii) irrigated, well watered conditions, or iv) bean fly protection with chemicals. Seed yield exhibited positive and significant correlations with leaf chlorophyll content, vertical root pulling resistance, pod harvest index, pods per plant and seeds per pod at both phenotypic and genotypic levels under stress and non-stress conditions. Genotypic correlations of traits with seed yield were greater than their respective phenotypic correlations across environments indicating the greater contribution of genotypic factors to the trait correlation. Pods per plant and seeds per pod had high positive direct effects on seed yield both under stress and non-stress whereas pods per plant had the highest indirect effect on seed yield through pod harvest index under stress.In general, our results suggest that vertical root pulling resistance and pod harvest index are important selection objectives for improving seed yield in common beans under non-stress and stress conditions, and particularly useful for drought and BSM tolerance evaluation.展开更多
基金Supported by the National Natural Science Foundation of China(No.51575014,51505020)Key Foundation Project of China Academy of Railway Sciences(No.2021YJ200).
文摘In the structure of double-nut ball-screw mechanism(BSM),the contact angle of the ball-screw determines the relative positional relationship between the balls and the screw as well as the nut.The contact angle is related to geometrical parameters of the ball,the screw and the nut,which are also affected by the running status and the preload of the BSM.Considering the effect of the gy-roscopic moment on the ball in the raceway,the dynamic model of the ball in space is established under different speeds and different preloads of the BSM.By simulation of the dynamic model of the ball in space,the changing regularity of the contact angle,the helix angle,the drag torque and the mechanical efficiency of the BSM can be obtained under different speeds and different preloads.The results show that there is a nonlinear gradient relationship between contact angle,helix angle,the drag torque,the mechanical efficiency and the speeds of the ball-screw under different preloads.The contact angle is the key factor to affect the drag torque of the BSM.Through the analysis,it is found that establishing the ball dynamic model in space can better study the precision degradation law of the ball screw.
文摘碳交易市场是实现“双碳”目标的重要途径,丰富的碳金融衍生品有助于增加碳市场活性,可以更好地发挥发现价格和风险管理功能。本文借鉴欧洲碳排放权交易体系中的碳期货期权产品,设计了我国的以碳排放配额为标的碳期权合约,并选择BSM模型作为碳期权的基础定价模型,描述碳价波动率与碳价之间的变化过程。研究发现,全国碳交易市场是非有效市场,具有反持久性特点,全国碳排放配额收益率具有明显的条件异方差特征,且波动具有显著的持续性。基于此,应加快完善碳市场建设,积极开展碳金融创新实践,加强碳交易市场国际合作。The carbon trading market is an important way to achieve the goal of “double carbon”. Rich carbon financial derivatives can help to increase the activity of the carbon market and better play the role of price discovery and risk management. Based on the carbon futures option products in the European carbon emission trading system, this paper designs a carbon option contract with carbon emission quota as the target in China, and chooses BSM model as the basic pricing model of carbon options to describe the changing process between carbon price volatility and carbon price. It is found that the national carbon trading market is inefficient and anti-persistent, and the national carbon emission quota yield has obvious conditional heteroscedasticity characteristics, and the fluctuation has obvious persistence. Based on this, we should speed up the improvement of carbon market construction, actively carry out carbon financial innovation practice, and strengthen international cooperation in carbon trading market.
文摘通过总结所有IaaS(infrastructure as a service)云服务定价的方法,明确了pay-per-use和subscription是目前业界普遍采用的两种定价方法,分析了IaaS云服务定价影响因素,并把IaaS云计算服务的五大基础参数(初始投资、合同期限、资源折旧、服务质量和资源年限)映射到BSM模型中,利用复利摩尔定律和BSM模型公式计算出IaaS云服务在两种定价方法(pay-per-use和subscription)下相对应的价格范围,并分析了两种定价方法的适应范围,更好地解决了现阶段对于IaaS云服务定价中只有云计算服务提供商单边定价的弊端,并从云计算服务提供商和用户两者的角度提供了对于IaaS服务价格的衡量标准。
文摘造纸污水具有处理量大、有机物污染负荷高的特点,但是对其处理过程中温室气体的大量排放长期以来关注不足。以国际公认的BSM1平台为基础,采用Benchmark simulation model No.1(BSM1)标准数据,根据微生物生长动力学及物料平衡关系,从污水生化处理工艺的四个方面,建立了温室气体排放计算模型,实现了污水生化处理过程中温室气体排放的动态计算。研究结果表明,污水生化处理过程中的总温室气体排放量为0.419 kg CO_2/m^3污水,其中具有高温室效应潜势的N_2O对温室气体的总排放的影响高达13%,应引起重视。
基金the Alliance for Green Revolution in Africa (AGRA) PASS project for providing financial support for the field studythe South Agricultural Research Institute (SARI) for hosting this researchDrs. I.M. Rao and B. Raatz at CIAT for supplying methods to analyze the recombinant inbred lines used as well the Bill and Melinda Gates Foundation through the Generation Challenge Program (GCP), Tropical Legume I (TL-I) project, for financial support to the research
文摘Understanding functional relations among plant traits and their modulation by growing conditions is imperative in designing selection strategies for breeding programs. This study assessed trait relationships among 196 common bean genotypes exposed to stresses for drought and field infestation of bean fly or bean stem maggot(BSM). The study was carried out at two locations and data was analyzed with linear correlation, path coefficient and genotype × trait biplot analyses. Multiple trait data related to mechanisms of drought and bean fly tolerance were collected on 196 genotypes grown under i) water deficit at mid-pod fill, or ii) unprotected against bean fly; iii) irrigated, well watered conditions, or iv) bean fly protection with chemicals. Seed yield exhibited positive and significant correlations with leaf chlorophyll content, vertical root pulling resistance, pod harvest index, pods per plant and seeds per pod at both phenotypic and genotypic levels under stress and non-stress conditions. Genotypic correlations of traits with seed yield were greater than their respective phenotypic correlations across environments indicating the greater contribution of genotypic factors to the trait correlation. Pods per plant and seeds per pod had high positive direct effects on seed yield both under stress and non-stress whereas pods per plant had the highest indirect effect on seed yield through pod harvest index under stress.In general, our results suggest that vertical root pulling resistance and pod harvest index are important selection objectives for improving seed yield in common beans under non-stress and stress conditions, and particularly useful for drought and BSM tolerance evaluation.
