分类: 统计学 >> 社会统计学 提交时间: 2024-03-27 合作期刊: 《中国科学院院刊》
摘要: 为践行“绿水青山就是金山银山”和“山水林田湖草沙是生命共同体”协调发展的理念,文章以党的 二十大报告中提出的“推动绿色发展,促进人与自然和谐共生”为理论指导,以提升生态系统完整性与连通 性、增进种群交流、提高种群生存力、建设旗舰物种生态廊道提供示范为目标,基于亚洲象种群分布现状及 栖息地选择策略,按照“获取物种分布—识别源地斑块和阻力面—基于最小成本路径模型构建廊道—通过电 流模型分析廊道中心度、生态夹点和障碍点—实地勘察—调整优化生态廊道设计—推荐廊道建设设计方案— 对野生动物利用生态廊道开展长期监测”的技术流程,提出了亚洲象生态廊道建设构想及相关保护建议。上 述构想和建议服务于“加大生态系统保护力度”“优化生态安全屏障体系,构建生态廊道和生物多样性保护 网络”的战略布局,可为亚洲象种群的科学保护和有效管理提供技术支撑,为栖息地恢复与拟建亚洲象国家 公园等自然保护地的布局提供科学依据。
分类: 其他 >> 综合 提交时间: 2024-03-28 合作期刊: 《文献与数据学报》
摘要: [目的 / 意义]皮书评价在皮书发展过程中发挥着关键的引领作用,是皮书分级资助、评奖及淘汰的重要衡量依据。科学合理的皮书影响力评价指标体系能够为皮书评价工作的有序进行提供保障,对于保证评价结果公正客观、推动皮书评价发挥学术引领作用具有重要意义。[方法 / 过程]采用文献调查法、问卷调查法及层次分析法,综合考虑各项原则,设置决策影响力、学术影响力、使用影响力和社会影响力 4 个一级指标,下设 10 个二级指标和 16 个三级指标,确定指标权重,选择 51 本第十二届“优秀皮书奖”皮书进行实证研究。[结果 / 结论] 本文实证研究结果与实际获奖情况存在关联,构建的皮书影响力评价指标体系具有一定的有效性和合理性,提出了优化皮书评价的建议。
分类: 统计学 >> 社会统计学 提交时间: 2024-03-27 合作期刊: 《中国科学院院刊》
摘要: 对涉及国家安全和利益的技术实施严格的出口管制是国际通行做法。近年来,随着大国竞争博弈加 剧,美国、欧洲、日本等发达国家和地区纷纷调整其技术出口管制政策。在总结国外技术出口管制演进历程 的基础上,重点分析了美西方国家对华技术出口管制的最新动向和对我国科技创新的影响。从完善技术出口 管制制度体系、强化战略性技术攻关能力、优化自主创新生态环境等方面提出了应对策略和政策建议。
分类: 统计学 >> 社会统计学 提交时间: 2024-03-27 合作期刊: 《中国科学院院刊》
摘要: 我国山地灾害易发区与经济社会发展滞后区的空间范围高度重叠,长期以来形成的减灾与发展间的疏 离和脱节问题,造成极大的资源浪费,成为制约2035 年山区同步迈向现代化的关键障碍。文章在系统梳理山 区综合减灾与产业发展面临的主要挑战基础之上,基于人地协调论思想创新发展易灾山区的“灾—地—人” 绿色协同理论,提出综合减灾与特色产业协同发展的新理念和新模式,剖析了该模式的内外部协同机制、主 要协同路径和关键协同技术;系统介绍了四川省凉山彝族自治州喜德县红莫镇热水河小流域综合减灾与产业 发展协同示范区建设成果;讨论了在全国山区推广综合减灾与产业发展协同模式的必要性、可行性及具体路 径。成果可用于指导我国广大山区巩固脱贫攻坚成效,全面推进乡村振兴战略实践,也有助于提高山区的统 筹与治理能力,支撑山区现代化建设。
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Correlated red noise recently reported from pulsar timing observations may be an indication of stochastic gravitational waves emitted by cosmic strings that formed during a primordial phase transition near the Grand Unification energy scale. Unfortunately, known probes of cosmic strings, namely the Cosmic Microwave Background anisotropies and string lensing of extragalactic galaxies, are not sensitive enough for low string tensions of $G\mu = 10^{-10}-10^{-7}$ that are needed to explain this putative signal. We show that strong gravitational lensing of Fast Radio Bursts (FRBs) by cosmic strings is a potentially unambiguous avenue to probe that range of string tension values. The image pair of string lensing are expected to have identical magnification factor and parity, and have a typical time delay of $\sim 10^2\,\,(G\,\mu/10^{-8})^2$ seconds. The unique spectral fingerprint of each FRB, as well as the possibility to detect correlations in the time series of the electric field of the radio waves, will enable verification of the string lensing interpretation. Very-Long-Baseline Interferometry (VLBI) observations can spatially resolve the image pair and provide a lower bound on the string tension based on the image separation. We calculate the FRB lensing rate as a function of FRB detection number for several different models of the FRB redshift distribution. We find that a survey detecting $\sim 10^5$ FRBs, in line with estimates for the detection rate of the forthcoming survey CHORD, can uncover a strong lensing event for a string tension of $G\mu \simeq 10^{-7}$. Larger FRB surveys, such as Phase 2 of the Square Kilometre Array (SKA), have the potential to significantly improve the sensitivity on the string tension to $G\mu \simeq 10^{-9}$.
分类: 统计学 >> 社会统计学 提交时间: 2024-03-27 合作期刊: 《中国科学院院刊》
摘要: 2023 年在疫情以后国民经济保持恢复态势,中国经济向着积极的方向复苏。但是经济恢复存在一定波 动,预测2024 年中国经济将平稳较快增长。文章综合运用了投入产出技术、景气分析、专家分析、统计和计 量经济模型来预测国内生产总值(GDP)。通过回顾2023 年中国的经济运行状况,并考虑到当下国内外的形 势,预测显示2024 年中国经济有望保持平稳运行,增速达到5.3%左右;基于对当前经济状况的分析,文章 提出如下建议:加强宏观政策跨周期和逆周期调节力度;提升产业链现代化水平,提高产业链韧性和竞争 力;稳定支持中小企业的发展。
分类: 统计学 >> 社会统计学 提交时间: 2024-03-27 合作期刊: 《中国科学院院刊》
摘要: 近年来,人工智能(AI) 在前沿科技领域取得了诸如AlphaFold2、核聚变智能控制、新冠药物设计等 诸多令人瞩目成果,表明AI for Science 正在成为一种新的研究范式。实现智能时代的基础科学源头创新及其 下游重大技术创新,需破解2 个方面的核心问题:(1) 如何利用新一代AI (特别是生成式AI及大模型) 的通 用性和创造性推动新范式的形成;(2) 如何利用AI实现对传统科学设施的赋能与改造。文章提出一种智能化 科学设施的建设构想,兼顾“高度智能化的科学新设施”和“AI 赋能已有科学大设施”2 个层面的需求,构 筑AI for Science 的科学设施体系,形成科学领域大模型、生成式模拟与反演、自主智能无人实验及大规模可 信科研协作等创新功能,加速重大科学发现、变革性物质合成,以及重大工程技术应用。
分类: 统计学 >> 社会统计学 提交时间: 2024-03-27 合作期刊: 《中国科学院院刊》
摘要: 随着社会的发展,需要用语言表达的信息是巨量的。由于新的信息、技术和物品不断大量出现,表达 和命名都不是一个简单的问题,需要大量合适的词汇,也需要新的字。针对这些问题,文章思考了汉语字词 扩展的必要性。
分类: 统计学 >> 社会统计学 提交时间: 2024-03-27 合作期刊: 《中国科学院院刊》
摘要: 文章以我国297 个地级及以上城市为分析对象,对其2023 年以来经济运行的总体情况、亮点热点和突 出问题进行分析回顾,并展望2024 年城市经济运行态势。总体来看,2023 年以来我国城市经济运行总体回 升向好,各领域亮点热点频现,但出口下行明显、房地产风险频发、地方债务风险加大、消费需求释放不足 等问题不容忽视。展望2024 年上半年,房地产、投资、消费、开放等领域宏观调控的政策效应将集中释放, 各城市应突出问题导向,准确把握2024 年发展重点,制定针对性政策举措,推动城市经济高质量发展。
分类: 图书馆学、情报学 >> 情报资料的处理 提交时间: 2024-03-28 合作期刊: 《文献与数据学报》
摘要: [目的 / 意义]智慧图书馆研究不仅要聚焦当下、探索未来,亦需回顾过往、追根溯源。本文通过对国际智慧图书馆领域历史根源文献进行识别与分析,为研究者梳理领域发展脉络、发现重要节点文献提供参考。[方法 / 过程]以 Web of Science 核心数据集中的智慧图书馆领域 617 篇施引文献、14 949篇参考文献为数据源,基于 CRExplorer 软件引文出版年光谱功能,构建了历史根源文献识别与分析框架。依据参考文献年度被引量、5 年平均中值偏差曲线变化趋势,将该领域研究阶段划分为铺垫期、萌芽期、初始发展期以及快速发展期,在此基础上,识别出历史根源文献 17 篇。[结果 / 结论]通过文献分析发现,智慧图书馆领域研究呈现历史根源文献存在显著跨学科性、研究内容从技术至理论与用户体验转变、典型研究主题连续性较弱且出现时间间隔较大、作者多以“大家”为主且新生力量近年崭露头角等特征。
分类: 统计学 >> 社会统计学 提交时间: 2024-03-27 合作期刊: 《中国科学院院刊》
摘要: 三江源国家公园是我国正式设立的首批国家公园之一,也是我国面积最大的国家公园,作为我国重要 的生态安全屏障和高原生物种质资源库,在全国乃至世界范围都具有重大的保护价值。针对三江源国家公园 生物多样性丧失、野生动物栖息地破坏、高寒草地退化和家畜超载放牧等一系列生态保护问题,基于草地多 功能目标管理理论创新和生物多样性保护新技术研发,推动生态保护、修复重大工程的落地实施,形成了三 江源国家公园生物多样性保护和民生改善的科技支撑新范式,为我国生态文明建设提供了实践方案,为全球 国家公园建设提供了中国智慧,为全球生物多样性保护提供了中国方案。
分类: 统计学 >> 社会统计学 提交时间: 2024-03-27 合作期刊: 《中国科学院院刊》
摘要: 大型复杂污染场地的污染治理修复是国内外环境领域面临的重大难题。大型复杂污染场地具有影响范 围广、污染物种类多、生态环境威胁大等特征,这类场地污染物的环境行为认知和高效治理修复都面临巨大 挑战,其中土壤和地下水污染的形成机制、污染源的精准识别、智能决策优化等关键科技问题亟待解决。我 国大型复杂污染场地在京津冀、长江经济带、珠江三角洲等经济发达地区呈集群式分布,涉及化学品制造 业、石油等燃料加工业、黑色金属冶炼等行业。基于我国国情,文章提出了大型复杂污染场地修复治理的关 键“三步曲”(TSRTCM),从调查评估与科学认知、方案决策与技术筛选、工程实施与监测评价3 方面着力 破解修复治理难题。大型复杂污染场地环境修复能有力支撑污染防治攻坚战,有助于区域经济社会绿色 发展。
分类: 统计学 >> 社会统计学 提交时间: 2024-03-27 合作期刊: 《中国科学院院刊》
摘要: 固体废弃物长期堆存和粗放处置利用造成严重的水-土-气复合污染,加强固体废弃物的科学有效利用, 不仅利于解决我国固废重大污染问题,还能缓解我国资源能源短缺困境。文章梳理了3 种典型类别的城市固 废综合处理经验模式,指出以集中化、资源化、绿色化为特征的固废循环经济处置利用模式是解决我国固废 复杂问题的主要途径,因此急需系统地开展城市多源固废协同利用模式下的关键技术、装备,以及资源能源 环境系统集成优化控制研究。以东莞海心沙国家资源循环利用示范基地发展实践为例,阐述了通过突破垃圾 焚烧、餐厨制沼、市政污泥热解、电子污泥熔炼、废矿物油蒸馏、全过程代谢模拟数字孪生等一系列城市多 源固废资源能源协同清洁高效回收与智能管控关键技术,大幅提升了基地的资源能源综合回收效率,降低了 区域环境综合影响水平,真正实现了粤港澳大湾区典型城市多源固废的资源能源耦合高效利用和环境友好型 发展。最后,从固废精细化管理、循环发展模式创新、无废社会建设等方面展望了城市多源固废综合利用与减污降碳协同发展的重点方向。
分类: 其他 >> 综合 提交时间: 2024-03-28 合作期刊: 《文献与数据学报》
摘要: [目的 / 意义]标准数字化能够深度挖掘标准潜在知识,并释放标准潜在价值。标准数字化治理战略直接关乎我国数字经济发展和国际竞争力的提升。[方法 / 过程]基于全球标准数字化变革趋势,从新技术、发展政策、发展格局、治理理念四方面进行研究。[结果 / 结论]研究结果表明:(1)标准数字化治理需把握四个机遇,一是标准数字化新技术促进标准链产业链全链条发展,二是标准化发展政策鼓励引导标准数字化发展,三是传统标准化发展格局产生变革,四是标准数据治理理念发生改变。(2)标准数字化治理正面临三个挑战,一是基本理论、关键技术、实施路径和应用场景尚未形成完整体系,二是成熟产品和优秀试点案例较少,三是制度体系和管理机制有待健全和完善。(3)标准数字化治理需考虑四项对策,一是大力发展基础概念体系和基础共性关键技术,二是强化相关政策保障,三是推动相关理论与各类业务场景融合和创新应用,四是提前谋划未来国际市场。
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: We measure for the first time the outermost edges of the Milky Way (MW) halo in terms of the depletion and turnaround radii. The inner depletion radius, $r_\mathrm{id}$, identified at the location of maximum infall velocity, separates a growing halo from the draining environment, while the turnaround radius, $r_\mathrm{ta}$, marks the outermost edge of infalling material towards the halo, both of which are located well outside the virial radius. Using the motions of nearby dwarf galaxies within $3\mathrm{Mpc}$, we obtain a marginal detection of the infall zone around the MW with a maximum velocity of $v_\mathrm{inf, max}=-46_{-39}^{+24}\mathrm{km s^{-1}}$. This enables us to measure $r_\mathrm{id}=559\pm 107 \mathrm{kpc}$ and $r_\mathrm{ta}=839\pm 121 \mathrm{kpc}$. The measured depletion radius is about 1.5 times the MW virial radius ($R_\mathrm{200m}$) measured from internal dynamics. Compared with halos in the cosmological simulation Illustris TNG100, the factor 1.5 is consistent with that of halos with similar masses and dynamical environments to the MW but slightly smaller than typical values of Local Group analogs, potentially indicating the unique evolution history of the MW. These measurements of halo edges directly quantify the ongoing evolution of the MW outer halo and provide constraints on the current dynamical state of the MW that are independent from internal dynamics.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: The Solar System's orbital structure is thought to have been sculpted by an episode of dynamical instability among the giant planets. However, the instability trigger and timing have not been clearly established. Hydrodynamical modeling has shown that while the Sun's gaseous protoplanetary disk was present the giant planets migrated into a compact orbital configuration in a chain of resonances. Here we use dynamical simulations to show that the giant planets' instability was likely triggered by the dispersal of the gaseous disk. As the disk evaporated from the inside-out, its inner edge swept successively across and dynamically perturbed each planet's orbit in turn. The associated orbital shift caused a dynamical compression of the exterior part of the system, ultimately triggering instability. The final orbits of our simulated systems match those of the Solar System for a viable range of astrophysical parameters. The giant planet instability therefore took place as the gaseous disk dissipated, constrained by astronomical observations to be a few to ten million years after the birth of the Solar System. Terrestrial planet formation would not complete until after such an early giant planet instability; the growing terrestrial planets may even have been sculpted by its perturbations, explaining the small mass of Mars relative to Earth.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: A general covariant local field theory of the holographic dark energy model is presented. It turns out the low energy effective theory of the holographic dark energy is the massive gravity theory whose graviton has 3 polarisations, including one scalar mode and two tensor modes. The Compton wavelength is the size of the future event horizon of the universe. The UV-IR correspondence in the holographic dark energy model stems from the scalar graviton's strong coupling at the energy scale that marks the breaking down of the effective field theory.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Thermoelastic loss is one of the main energy dissipation mechanisms in resonant systems. A careful analysis of the thermoelastic loss is critical to design low-noise resonators for high-precision applications, such as gravitational-wave detectors. This paper presents an analytical solution to the thermoelastic loss in multimaterial coated finite substrates with realistic assumptions on the model structure and the elastic fields. The mechanism responsible for thermoelastic loss is taken as a function of material properties, operating temperature and frequency, and other design parameters. We calculate the thermoelastic loss for specific applications over a wide range of frequencies (1 Hz to 10 GHz) and temperatures (1 K to 300 K), and for a variety of substrate and coating materials. The result is relevant for gravitational-wave detectors and for experiments sensitive to mechanical dissipation.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Potential features in the primordial power spectrum have been searched for in galaxy surveys in recent years since these features can assist in understanding the nature of inflation. The null detection to date suggests that any such features should be fairly weak, and next-generation galaxy surveys, with their unprecedented sizes and precisions, are in a position to place stronger constraints than before. However, even if such primordial features once existed in the early Universe, they would have been significantly damped in the nonlinear regime at low redshift due to structure formation, which makes them difficult to be directly detected in real observations. A potential way to tackle this challenge for probing the features is to undo the cosmological evolution, i.e., using reconstruction to obtain an approximate linear density field. By employing a set of N-body simulations, here we show that a recently-proposed nonlinear reconstruction algorithm can effectively retrieve damped oscillatory features from halo catalogues and improve the accuracy of the measurement of feature parameters (assuming that such primordial features do exist). We do a Fisher analysis to forecast how nonlinear reconstruction affects the constraining power, and find that it can lead to significantly more robust constraints on the feature amplitude for a DESI-like survey. Comparing nonlinear reconstruction with other ways of improving constraints, such as increasing the survey volume and range of scales, this shows that it is possible to achieve what the latter do, but at a lower cost.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: Building accurate and predictive models of the underlying mechanisms of celestial motion has inspired fundamental developments in theoretical physics. Candidate theories seek to explain observations and predict future positions of planets, stars, and other astronomical bodies as faithfully as possible. We use a data-driven learning approach, extending that developed in Lu et al. ($2019$) and extended in Zhong et al. ($2020$), to a derive stable and accurate model for the motion of celestial bodies in our Solar System. Our model is based on a collective dynamics framework, and is learned from the NASA Jet Propulsion Lab's development ephemerides. By modeling the major astronomical bodies in the Solar System as pairwise interacting agents, our learned model generate extremely accurate dynamics that preserve not only intrinsic geometric properties of the orbits, but also highly sensitive features of the dynamics, such as perihelion precession rates. Our learned model can provide a unified explanation to the observation data, especially in terms of reproducing the perihelion precession of Mars, Mercury, and the Moon. Moreover, Our model outperforms Newton's Law of Universal Gravitation in all cases and performs similarly to, and exceeds on the Moon, the Einstein-Infeld-Hoffman equations derived from Einstein's theory of general relativity.