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Floquet spectrum and universal dynamics of a periodically driven two-atom system
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作者 谢文柱 周正强 +2 位作者 李轩 崔思淼 孙明远 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第2期436-443,共8页
We investigate the Floquet spectrum and excitation properties of a two-ultracold-atom system with periodically driven interaction in a three-dimensional harmonic trap.The interaction between the atoms is changed by va... We investigate the Floquet spectrum and excitation properties of a two-ultracold-atom system with periodically driven interaction in a three-dimensional harmonic trap.The interaction between the atoms is changed by varying the s-wave scattering length in two ways,the cosine and the square-wave modulations.It is found that as the driving frequency increases,the Floquet spectrum exhibits two main features for both modulations,the accumulating and the spreading of the quasienergy levels,which further lead to different dynamical behaviors.The accumulation is associated with collective excitations and the persistent growth of the energy,while the spread indicates that the energy is bounded at all times.The initial scattering length,the driving frequency and amplitude can all significantly change the Floquet spectrum as well as the dynamics.However,the corresponding relation between them is valid universally.Finally,we propose a mechanism for selectively exciting the system to one specific state by using the avoided crossing of two quasienergy levels,which could guide preparation of a desired state in experiments. 展开更多
关键词 Floquet spectrum universal dynamics two-atom system avoided crossing
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Abnormal thermal expansion coefficients in(Nd_(1−x)Dy_(x))_(2)Zr_(2)O_(7) pyrochlore:The effect of low-lying optical phonons 被引量:2
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作者 Zesheng Yang Yi Li +1 位作者 Wei Pan Chunlei Wan 《Journal of Advanced Ceramics》 SCIE EI CAS CSCD 2023年第5期1001-1014,共14页
Chemical doping is a normal strategy to tune thermal expansion coefficient(TEC)of ceramics in engineering applications,but the resultant TEC values usually follow Vegard’s law,as doping does not modify the nature of ... Chemical doping is a normal strategy to tune thermal expansion coefficient(TEC)of ceramics in engineering applications,but the resultant TEC values usually follow Vegard’s law,as doping does not modify the nature of chemical bonding in ceramics and its anharmonicity.In this paper,we report abnormal TEC behavior in(Nd_(1−x)Dy_(x))_(2)Zr_(2)O_(7) ceramics,where the TEC values remarkably exceed the values predicted by Vegard’s law and even exceed the values obtained for two constituents Nd_(2)Zr_(2)O_(7) and Dy_(2)Zr_(2)O_(7).In addition to a reduction in lattice energy with an increasing molar fraction of Dy(x)value,we attribute the additional increase in the TEC to the high concentration of Dy dopants in a pyrochlore(P)region,which can soften low-lying optical phonon modes and induce strongly avoided crossing with acoustic phonon branches and enhanced anharmonicity.We believe that this finding can provide a new route to break through the restriction imposed by the conventional Vegard’s law on the TEC values and bring new opportunities for thermal barrier coatings(TBCs)or ceramic/metal composites towards realizing minimized thermal mismatch and prolonged service life during thermal cycling. 展开更多
关键词 thermal barrier coating(TBC) thermal expansion first-principles calculations avoided crossing
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Environmental benefits for a geothermal power plant with CO_(2) reinjection:case study of the Kizildere 3 U1 geothermal power plant 被引量:1
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作者 María Dolores Mainar-Toledo Ural Halaçoglu +4 位作者 Hakan Alp Sahiller Tugrul Hazar Claudio Zuffi Maryori Díaz-Ramírez Giampaolo Manfrida 《Energy Storage and Saving》 2023年第4期631-638,共8页
Geothermal power plants(GPP)with high non condensable gases(NCG)content geothermal fluid have shown to be environmental impacting relating to their energy production,which could be critical if no corrective actions ar... Geothermal power plants(GPP)with high non condensable gases(NCG)content geothermal fluid have shown to be environmental impacting relating to their energy production,which could be critical if no corrective actions are achieved.The GPP of Kizildere 3 U1,located in Türkiye(Denizli),in where the geothermal fluid contains high percentage of CO_(2),99%of the NCG fraction,which represents the 3%of the geothermal fluid mass,is taken as a relevant case study to implement a new innovation consisting of NCG reinjection to reduce the amount of NCGs released to the atmosphere.In order to calculate the present environmental impacts which the plant is causing(baseline);and the potential reduction of environmental impacts which can be achieved with the innovation(reinjection),a life cycle assessment(LCA)calculation were developed.Primary data were collected for all the relevant stages of the energy conversion cycle and complemented where necessary with secondary data from other geothermal power plants studies.The main results of the baseline environmental assessment show that the construction phase is the most impacting phase due to the materials used in the power plant building construction,electrical generation equipment and distributed machinery and infrastructures;the effects in the operation phase are dominated by the geothermal fluid composition.In this sense,the application of CO_(2) reinjection at the Turkish site into the reservoir will prevent the emission of 1,700 tons⋅year1 in the pilot site and 10%of the total emissions released along the life span of the GPP. 展开更多
关键词 Life cycle assessment Geothermal energy Non-condensable gases REINJECTION CO_(2)emissions avoided
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Environmental Impacts of Grid Connected High Concentrated Photovoltaic Systems Adapted for Peak Load Minimization in Hot Climate
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作者 Talal H. Alzanki Kandil M. Kandil +1 位作者 Mohammad R. Alenezi Adel A. Ghoneim 《Smart Grid and Renewable Energy》 2018年第11期237-258,共22页
High concentrated PV multi-junction solar cells (HCPV) likely present a favorable alternative to achieve low cost of energy. However, multi-junction solar cell has different characteristics which should be settled bef... High concentrated PV multi-junction solar cells (HCPV) likely present a favorable alternative to achieve low cost of energy. However, multi-junction solar cell has different characteristics which should be settled before they can be adapted for large scale energy generation. Peak energy consumption in Kuwait usually occurs in periods of utilizing air conditioning systems which are essentially used in almost all year around in harsh climate like Kuwait. Power consumed at peak times is more costly than power needed to satisfy loads at regular consumption times. The main goal of the present research is to increase HCPV solar cells’ efficiency, to decrease maximum power cost in Kuwait. Multi-junction solar cells performance in weather conditions of Kuwait is investigated employing a single diode equivalent circuit model. The model developed considers the impacts of concentration ratio as well as temperature. Most research in literature review usually neglects shunt resistance of the diode, however this resistance is taken into consideration in current developed theoretical model. To calibrate the present model, current predictions are compared with corresponding measured data provided by multi-junction solar cell manufacturer. The total root mean square errors in the present model predictions are about 1.8%. This means that current developed model of single diode model which takes into account shunt resistance impacts gives precise and reliable data. HCP electrical efficiency is noticed to rise as concentration increases but to a certain concentration value, then it begins to decrease. In addition, utilizing HCPV linked to grid satisfies great decrease in maximum load. Power produced from HCPV modules is utilized to provide energy needs to a family in normal Kuwaiti family home to evaluate HCPV environmental effects. HCPV modules slopes and areas are changed to accomplish peak energy production all over the year. Present results reveal that optimum power production corresponds to HCPV modules directed to south and 展开更多
关键词 HIGH Concentrated PHOTOVOLTAIC Systems avoided CO2 Emission MAXIMUM Load
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Economic Assessment of Large Grid-connected Wind Farms——Avoided Cost Method
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作者 魏婕 郭元 顾树华 《Tsinghua Science and Technology》 SCIE EI CAS 1999年第1期73-76,共4页
mong the many forms of renewable energy generation, wind power is the most mature. However, the method used to assess the economic value of large grid connected wind farms still needs further study. At present the tra... mong the many forms of renewable energy generation, wind power is the most mature. However, the method used to assess the economic value of large grid connected wind farms still needs further study. At present the traditional method of project economic assessment as widely used in China isolates the wind farm from the whole power system and ignores the influence of reliability on the cost of wind generation; therefore, the evaluation results can not reflect the true economic value of wind power generation. After reviewing the many assessment methods used at home and abroad, this paper uses the Avoided Cost Method as theoretical basis to establish an economic evaluation model for large wind farms including the characteristics of other conventional forms of power generation like thermal power as well as the system load. The generating reliability is also combined into the economic evaluation. The model is used to evaluate China's largest wind farm, Dabancheng Wind Farm in Xinjiang. 展开更多
关键词 avoided cost economic evaluation reliability evaluation large wind farms〖ZK
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Adapting Integrated High Concentrated PV Modules and Evacuated Tube Collectors to Minimize Building Energy Consumption in Hot Climate
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作者 Talal H. Alzanki Kandil M. Kandil 《Smart Grid and Renewable Energy》 2019年第10期237-256,共20页
Energy consumption in buildings is considered a significant portion of gross power dissipation, so a great effort is required to design efficient construction. In severe hot weather conditions as Kuwait, energy requir... Energy consumption in buildings is considered a significant portion of gross power dissipation, so a great effort is required to design efficient construction. In severe hot weather conditions as Kuwait, energy required for building cooling and heating results in a huge energy loads and consumption and accordingly high emission rates of carbon dioxide. So, the main purpose of the current work is to convert the existing institutional building to near net-zero energy building (nNZEB) or into a net-zero energy building (NZEB). A combination of integrated high concentrated photovoltaic (HCPV) solar modules and evacuated tube collectors (ETC) are proposed to provide domestic water heating, electricity load as well as cooling consumption of an institutional facility. An equivalent circuit model for single diode is implemented to evaluate triple junction HCPV modules efficiency considering concentration level and temperature effects. A code compatible with TRNSYS subroutines is introduced to optimize evacuated tube collector efficiency. The developed models are validated through comparison with experimental data available from literature. The efficiency of integrated HCPV-ETC unit is optimized by varying the different system parameters. Transient simulation program (TRNSYS) is adapted to determine the performance of various parts of HCPV-ETC system. Furthermore, a theoretical code is introduced to evaluate the environmental effects of the proposed building when integrated with renewable energy systems. The integrated HCPV-ETC fully satisfies the energy required for building lighting and equipment. Utilizing HCPV modules of orientation 25? accomplishes a minimum energy payback time of about 8 years. Integrated solar absorption chiller provides about 64% of the annual air conditioning consumption needed for the studied building. The energy payback period (EPT) or solar cooling system is about 18 years which is significantly larger than that corresponding to HCPV due to the extra expenses of solar absorption system. The li 展开更多
关键词 HIGH Concentrated PHOTOVOLTAIC Evacuated Tube COLLECTOR Net-Zero Energy Building avoided CO2 Emission
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The Electricity Market Structure in Greece and the Paradox of Renewable Energy Sources
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作者 Ilias G. Doulos Nikolas M. Katsoulakos Dimitris C. Kaliampakos 《Journal of Power and Energy Engineering》 2019年第4期1-26,共26页
The European Union, in an effort to boost the use of Renewable Energy Sources (RES) in power generation, applies supportive tools consisting in financial motivation either as grants or as subsidies. According to welfa... The European Union, in an effort to boost the use of Renewable Energy Sources (RES) in power generation, applies supportive tools consisting in financial motivation either as grants or as subsidies. According to welfare economics, a subsidy should reflect the external benefits;otherwise a distortion of competition takes place. The most widespread method to calculate externalities is the avoided cost approach, despite the fact that it encounters equally all the RES units leading to technological neutrality. In the present article, the avoided cost approach with the objective social justification of RES subsidies/feed in tariffs (FITs) in the case of Greece, for the year 2014, is applied. The results show a high gap between the current FITs and the suggested ones amounting to approximately 40%. This uncomfortable outcome indicates that, at least in the case of Greece, either the level of the current guaranteed tariffs is not socially justified, or the CO2 value derived from the European carbon market does not reflect the real social cost, or that the avoided cost method, alone, is not adequate to explain the level of subsidies. In light of the foregoing, the need for the development of a concrete and integrated methodology for calculating all RES externalities emerges. 展开更多
关键词 RENEWABLE Energy Feed in TARIFF avoided Cost WELFARE ECONOMICS PRICING Externalities
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Improvement of the chirality near avoided resonance crossing in optical microcavity 被引量:1
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作者 SONG QingHai GU ZhiYuan +3 位作者 ZHANG Nan WANG KaiYang YI Ning Bo XIAO ShuMin 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2015年第11期55-62,共8页
Chirality is one of the important phenomena at the vicinity of exceptional point(EP). The conventional understanding is that the chirality is determined by asymmetrical scattering efficiency(?), which reaches to zero ... Chirality is one of the important phenomena at the vicinity of exceptional point(EP). The conventional understanding is that the chirality is determined by asymmetrical scattering efficiency(?), which reaches to zero only when the resonance approaches EP. Here we study the possibility to enhance the chirality in open systems with a more robust mechanism. By combining chirality with avoided resonance crossing, we show that the chirality and ? can be dramatically modified. Taking a spiral shaped annular cavity as an example, we show that the chirality of optical resonances can be significantly improved when two sets of chiral states approach each other. The imbalance between counterclockwise(CCW) components and clockwise(CW) components has been enhanced by more than an order of magnitude. Our research provides a new route to tailor and control the chirality in open systems. 展开更多
关键词 MICROCAVITY CHIRALITY avoided resonance crossing mode coupling
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Evolution of polarization singularities accompanied by avoided crossing in plasmonic system
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作者 彭一啸 宋前举 +3 位作者 胡鹏 崔大健 向红 韩德专 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第1期305-310,共6页
The evolution of polarization singularities supported in a one-dimensional periodic plasmonic system is studied.The lateral inversion symmetry of the system,which breaks the in-plane inversion symmetry and up-down mir... The evolution of polarization singularities supported in a one-dimensional periodic plasmonic system is studied.The lateral inversion symmetry of the system,which breaks the in-plane inversion symmetry and up-down mirror symmetry simultaneously,yields abundant polarization states.A complete evolution process with geometry for the polarization states is traced.In the evolution,circularly polarized points(C points)can stem from 3 different processes.In addition to the previously reported processes occurring in an isolated band,a new type of C point appearing in two bands simultaneously due to the avoided band crossing,is observed.Unlike the dielectric system with a similar structure which only supports at-Γbound states in the continuum(BICs),accidental BICs off theΓpoint are realized in this plasmonic system.This work provides a new scheme of polarization manipulation for the plasmonic systems. 展开更多
关键词 polarization singularities topological charge avoided crossing inversion symmetry
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S波段四腔强流相对论速调管的设计和实验研究 被引量:1
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作者 成会 谢鸿全 +2 位作者 刘迎辉 李正红 吴洋 《物理学报》 SCIE EI CAS CSCD 北大核心 2014年第1期372-378,共7页
本文根据四腔强流相对论速调管设计过程中出现的高次模振荡现象,采用电磁场软件模拟,分析了这种振荡的产生原因,给出抑制这种高次模振荡的方法.利用二维和三维模拟软件,研究了谐振腔谐振频率、谐振腔Q值、漂移管长度、特性阻抗等参数的... 本文根据四腔强流相对论速调管设计过程中出现的高次模振荡现象,采用电磁场软件模拟,分析了这种振荡的产生原因,给出抑制这种高次模振荡的方法.利用二维和三维模拟软件,研究了谐振腔谐振频率、谐振腔Q值、漂移管长度、特性阻抗等参数的变化对高次模振荡的影响,模拟上验证了高次模振荡抑制方法的有效性,并在输出端模拟获得了功率2.13 GW、效率26%、增益60 dB的输出微波,实现了2D,3D中高次模振荡的有效抑制.最终在实验中获得了功率1.9 GW、效率24%、增益61 dB的输出微波. 展开更多
关键词 四腔强流相对论速调管 电磁场模拟软件 高次杂模振荡 抑制
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“双碳”背景下火电机组CCUS应用的成本及收益分析
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作者 赵淑媛 刘骏 +2 位作者 袁鑫 陈衡 潘佩媛 《河北电力技术》 2023年第6期88-94,共7页
在“双碳”目标提出的背景下,为解决火电机组碳排放量高的问题,对其进行CCUS改造(Carbon Capture,Utilization and Storage,碳的捕集、利用与封存)。为了给企业投资CCUS项目提供更多可行性参考,综合当前电-碳双市场发展趋势总结并分析... 在“双碳”目标提出的背景下,为解决火电机组碳排放量高的问题,对其进行CCUS改造(Carbon Capture,Utilization and Storage,碳的捕集、利用与封存)。为了给企业投资CCUS项目提供更多可行性参考,综合当前电-碳双市场发展趋势总结并分析了火电机组进行碳捕集、压缩与运输的成本、收益情况及其影响因素,同时对2025-2060年碳捕集和运输成本的变化趋势进行合理预测。将某省火电机组作为典型案例,假设该省火电机组于2022年进行CCUS改造,对其2022-2070年的项目运行及收益情况进行计算与分析,收益中涵盖二氧化碳的地质利用与封存及碳交易。最终得出若2022年进行CCUS项目改造,则预计于2039-2040年间实现收益覆盖成本的目标,且项目周期中碳捕集费用在支出费用中占比最高,此外在整个项目周期中成本占比最高的环节为碳捕集环节等结论。 展开更多
关键词 火电机组 二氧化碳 CCUS 碳捕集成本 碳交易 驱油利用
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Building Sector: The Different Ways to Improve Their Energetic Efficiency
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作者 Clito Afonso Ricardo Pereira 《Journal of Environmental Science and Engineering(B)》 2016年第5期243-253,共11页
The building sector has a significant weight in the global energy consumption in almost of the countries. So, there is a high potential for increasing its energy efficiency. With the enforcement of the energetic certi... The building sector has a significant weight in the global energy consumption in almost of the countries. So, there is a high potential for increasing its energy efficiency. With the enforcement of the energetic certification, it was tried to select different solutions that presents less energy consumption and waste, as well as an effective reduction of CO2 emissions. This work fits in this perspective, since the main goal is to evaluate the contribution of passive and active solutions that can be used in buildings for the improvement of its energetic efficiency, as well as to evaluate the contribution of renewable energy sources. Contribution of solar systems for hot water heating and electric energy production has been studied, as well as cogeneration, Combined Heat and Power (CHP). The case studied is a hotel. To improve the building performance, there were proposed several changes, with the goal of evaluating the contribution of the different solutions proposed. It was concluded that they contribute to a reduction of thermal needs of 25.2% and avoided emissions of CO2 is 30.4%. The analysis of the implementation of trigeneration, Combined Heat, Cooling and Power (CHCP) turns it executable. The payback period is less than 8 years. 展开更多
关键词 CHP CHCP energy analysis avoided CO2 emissions economic analysis.
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煤矿安全监控技术与系统 被引量:106
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作者 孙继平 《煤炭科学技术》 CAS 北大核心 2010年第10期1-4,共4页
研究了煤矿安全监控系统在瓦斯、火灾等重特大事故防治和事故调查中的作用;分析了煤矿安全监控系统使用与管理存在的问题;提出了煤矿安全监控系统使用与管理技术要点:①甲烷、风速、风压、风筒、风门、局部通风机开停、主要通风机开停... 研究了煤矿安全监控系统在瓦斯、火灾等重特大事故防治和事故调查中的作用;分析了煤矿安全监控系统使用与管理存在的问题;提出了煤矿安全监控系统使用与管理技术要点:①甲烷、风速、风压、风筒、风门、局部通风机开停、主要通风机开停、馈电状态等传感器要按规定的数量和地点正确安装与维护;②根据被控对象的不同,正确连接甲烷断电闭锁和风电闭锁;③根据工作面和回风巷等不同地点,正确设置报警浓度、断电浓度、复电浓度和断电区域;④每隔10d使用校准气样和空气气样对甲烷传感器进行正确调校,同时对甲烷断电闭锁和风电闭锁功能进行测试;⑤甲烷超限报警、断电、馈电异常、停风报警后,要及时采取停电、撤人等安全措施。 展开更多
关键词 安全监控 灾害防治 预警 安全避险 六大系统 煤矿
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“避害型”府际合作何以可能?——基于京津冀大气污染联防联控的扎根理论研究 被引量:56
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作者 李辉 黄雅卓 +1 位作者 徐美宵 周颖 《公共管理学报》 CSSCI 北大核心 2020年第4期53-61,109,168,共11页
本文以京津冀大气污染联防联控为例,采用扎根理论构建府际合作的实现机制,为探索中国语境下"避害型"府际合作的规律提供新的路径。研究发现:中央纵向权力介入与地方横向协调间的策略性互动构成了"避害型"府际合作... 本文以京津冀大气污染联防联控为例,采用扎根理论构建府际合作的实现机制,为探索中国语境下"避害型"府际合作的规律提供新的路径。研究发现:中央纵向权力介入与地方横向协调间的策略性互动构成了"避害型"府际合作从提出到实施全过程的主轴。中央的任务压力与地方的合作成本分别作为正向和反向驱动因素,二者的差值决定了地方政府的合作意愿。中央过程压力与地方合作行动间的策略性互动在合作推动过程中发挥重要作用。依据二者强弱匹配的关系可以将"避害型"府际合作的生成模式分为自主探索型、应景响应型、压力回应型、命令指派型和直接组织型。在流域治理、空气污染治理等领域的府际合作中,中央政府既要适时施加任务压力和过程压力,也要根据地方政府合作意愿的强度及合作行动的积极性,将纵向权力介入控制在适度范围内。 展开更多
关键词 地方政府合作 “避害型”府际合作 京津冀大气污染联防联控 扎根理论
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低碳建筑的评价指标初探 被引量:42
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作者 龙惟定 张改景 +3 位作者 梁浩 苑翔 范蕊 白玮 《暖通空调》 北大核心 2010年第3期6-11,共6页
提出用"建筑利用中的人均碳排放指标"和"建筑用能过程碳减排效率"对低碳建筑进行评价。指出建筑碳排放实质上是人的碳排放,建筑只是使用者的能耗平台。因此,对建筑碳排放的评价要用强度指标,即建筑使用者人均碳排... 提出用"建筑利用中的人均碳排放指标"和"建筑用能过程碳减排效率"对低碳建筑进行评价。指出建筑碳排放实质上是人的碳排放,建筑只是使用者的能耗平台。因此,对建筑碳排放的评价要用强度指标,即建筑使用者人均碳排放指标。而对建筑设备的碳排放评价,是一个投入产出分析过程,即投入隐含碳、间接碳和直接碳,产出"避免碳排放量"的效率。同时计算得出我国太阳能光伏发电的隐含碳排放量。 展开更多
关键词 低碳建筑 评价指标 人均碳排放指标 碳减排效率 隐含碳排放 避免碳排放
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风电场的容量可信度和可避免费用计算 被引量:12
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作者 陈树勇 戴慧珠 +1 位作者 白晓民 周孝信 《太阳能学报》 EI CAS CSCD 北大核心 1999年第4期432-438,共7页
建立了风电场发电可靠性模型,考虑了风的随机性、风电机组的强迫停运率、尾流效应以及不同风电场之间风的相关性。基于该模型和电力系统随机生产模拟,提出风电场容量可信度和可避免费用的计算方法,这对并网风电场的规划具有十分重要... 建立了风电场发电可靠性模型,考虑了风的随机性、风电机组的强迫停运率、尾流效应以及不同风电场之间风的相关性。基于该模型和电力系统随机生产模拟,提出风电场容量可信度和可避免费用的计算方法,这对并网风电场的规划具有十分重要意义。 展开更多
关键词 风力发电 可靠性模型 容量可信度 可避免费用
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426份知情同意书缺陷分析 被引量:15
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作者 雍娟 《中国病案》 2011年第2期13-14,共2页
目的查找知情同意书存在的缺陷和改进措施,提高病历质量。方法回顾性分析2009年1月-6月的出院病案38 901份中知情同意书的填写情况。结果 38 901份病案中,知情同意书填写缺陷的病案426份,缺陷率1.10%。结论增强法律意识,规范知情同意书... 目的查找知情同意书存在的缺陷和改进措施,提高病历质量。方法回顾性分析2009年1月-6月的出院病案38 901份中知情同意书的填写情况。结果 38 901份病案中,知情同意书填写缺陷的病案426份,缺陷率1.10%。结论增强法律意识,规范知情同意书的书写,控制病历缺陷的发生,有利于提高病案质量,防止医疗纠纷发生。 展开更多
关键词 知情同意书 缺陷分析 防范措施
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分段路径寻优算法研究及实现 被引量:9
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作者 周鹏 张骏 史忠科 《计算机应用研究》 CSCD 北大核心 2005年第12期241-243,共3页
传统的路径寻优只考虑了起点和终点,不能满足一些用户的实际需求;研究了一类带有必经节点序列和避开节点序列的路径寻优问题。首先将必经节点序列进行有序调整,然后根据避开节点序列和调整后的必经节点序列进行分段路径寻优,最后生成满... 传统的路径寻优只考虑了起点和终点,不能满足一些用户的实际需求;研究了一类带有必经节点序列和避开节点序列的路径寻优问题。首先将必经节点序列进行有序调整,然后根据避开节点序列和调整后的必经节点序列进行分段路径寻优,最后生成满足用户要求的最短路径。将其应用到面向手机用户的路径诱导业务中,取得了良好的效果。 展开更多
关键词 分段路径寻优 搜索时间 必经节点序列 避开节点序列
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“避害型”府际合作中的纵向介入:一个整合性框架 被引量:9
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作者 李辉 《学海》 CSSCI 北大核心 2022年第4期126-134,146,共10页
与“趋利型”府际合作相比,“避害型”府际合作面临着更为复杂的集体行动困境,也更需要中央政府的纵向介入。本文遵循“集体性-选择性”“收益-损害”两种逻辑,对地方政府区域合作动机进行“二维-四分”的阐释,构建起关键行动者和合作... 与“趋利型”府际合作相比,“避害型”府际合作面临着更为复杂的集体行动困境,也更需要中央政府的纵向介入。本文遵循“集体性-选择性”“收益-损害”两种逻辑,对地方政府区域合作动机进行“二维-四分”的阐释,构建起关键行动者和合作动机的整合性框架。研究发现,“集体性损害≠选择性损害”是“避害型”府际合作困境的根源,包括合法性问题、理性主义陷阱、外部性困境以及合作成本障碍。纵向介入的工具和机制包括以纵向授权解决合法性困境的保障型介入、以纵向沟通规避理性主义陷阱的信息型介入、以纵向统合回应外部性困境的权威型介入、以纵向命令反制合作成本障碍的强制型介入。不同的介入方式形塑了“避害型”府际合作的不同生成模式,包括自主探索型、应景响应型、压力回应型、命令强制型、直接组织型。针对不同程度的府际合作困境选择恰当的介入工具和机制,有利于准确把握纵向介入的尺度,以最小介入成本达到促进府际合作的效用。 展开更多
关键词 地方政府合作 “避害型”府际合作 纵向介入 京津冀大气污染联防联控
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用B-样条函数研究静电场中锂原子里德伯态的性质 被引量:5
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作者 何永林 周效信 李小勇 《物理学报》 SCIE EI CAS CSCD 北大核心 2008年第1期116-123,共8页
用B-样条函数展开方法,结合原子的单电子势模型研究了静电场中锂原子里德伯态的性质.所得到的Stark能级图、反交叉位置、反交叉宽度以及振子强度与已有的实验和其他理论结果符合得很好.表明该方法是一种有效的研究静电场中碱金属原子性... 用B-样条函数展开方法,结合原子的单电子势模型研究了静电场中锂原子里德伯态的性质.所得到的Stark能级图、反交叉位置、反交叉宽度以及振子强度与已有的实验和其他理论结果符合得很好.表明该方法是一种有效的研究静电场中碱金属原子性质的方法.最后,在数值上研究了锂原子里德伯态振子强度谱随静电场场强的演化特征. 展开更多
关键词 B 样条函数 振子强度 反交叉位置 反交叉宽度
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