算法透明何以提升公众的政府信任?

随着算法辅助决策逐渐嵌入公共部门,算法黑箱极易冲击公众对于政府公权力的信任。算法透明成为政府治理的应有之义。然而,算法透明何以实现,以及政府信任与算法透明的关联仍存在争议。论文基于“金税工程”税务算法现实案例,设计了一个情景调查实验,实证检验了算法透明的实现机制及其对政府信任的影响路径。研究发现:(1)算法过程透明、算法结果透明均对公众感知算法透明具有显著正向影响;(2)感知算法透明能够提高公众对政府的信任;(3)算法信任在感知算法透明、政府信任中发挥了部分中介效应。研究明晰了算法透明的概念,回应了算法透明与信任的迷思,并阐明了其中的强化机制,为推进算法善治提供了实践参考。

储能用质子交换膜燃料电池长期老化预测

质子交换膜燃料电池(PEMFC)的长期老化预测有助于缩短耐久性测试时间,降低成本,为维护策略提供依据。针对超参数问题,提出一种将优化算法和储备池计算相结合的数据驱动预测方法。基于耐久性测试数据集,以电堆输出电压为老化指标,利用麻雀搜索算法(SSA)优化回声状态网络(ESN)的储备池尺寸、泄漏率和正则化系数,以构建预测模型。分别利用原始数据的前30%、40%、50%和60%作为训练集训练模型,验证模型在各训练集比例下的长期老化预测性能。训练集比例为30%时,所提方法在静态工况下的长期预测均方根误差(RMSE)达到0.0083,准动态工况下可达到0.0359。

中国式花园城市:理论构建与实践路径

花园城市是生态文明潮流下营造和谐人居环境的一种理想模式,与中国本土文化和城市发展形势相结合被赋予了更丰富的内涵。中国式花园城市吸收国外花园城市建设经验,延续中华传统自然山水观意蕴,拓展现代生态都市主义理论,成为建设人与自然和谐共生现代化的重要载体。其特性包括系统性、人民性、人文性、生态性、强韧性等。在具体构成上以城市要件、环境要件和连通要件为支撑,涵盖微观花园要素、中观花园场景、宏观花园体系三个层次。实践方面可在景观设计上建设开敞花园空间、在空间形态上打造全域花园体系、在功能设置上营造多元花园场景、在治理方式上共享多重花园红利。

载万古霉素缓释微球纳米羟基磷灰石/壳聚糖支架联合自体红骨髓可修复慢性骨髓炎兔的骨缺损

背景:前期研究证实,万古霉素缓释微球对兔慢性骨髓炎具有良好的治疗效果,纳米羟基磷灰石/壳聚糖具有良好的生物相容性、降解性及成骨诱导性,自体红骨髓联合纳米羟基磷灰石/壳聚糖支架可用于修复兔桡骨骨缺损。因此,3者联合修复兔慢性骨髓炎骨缺损的效果有待验证。目的:探讨载万古霉素/聚乳酸-羟基乙酸共聚物(polyactic-co-glycolicacid,PLGA)缓释微球的纳米羟基磷灰石/壳聚糖支架,联合自体红骨髓修复兔慢性骨髓炎骨缺损的治疗效果及可行性。方法:采用水-油-水乳相法制备万古霉素/PLGA缓释微球,将缓释微球与纳米羟基磷灰石/壳聚糖混合液充分混匀,采用真空冷冻干造法制备载万古霉素/PLGA缓释微球的纳米羟基磷灰石/壳聚糖支架,对支架进行力学性能测试及万古霉素释放量检测。在20只5月龄新西兰大白兔(解放军第三军医大学大坪医院实验动物中心提供)左侧胫骨髓腔内注射金黄色葡萄球菌,构建慢性骨髓炎骨缺损模型,随机分4组干预,A组仅作清创处理,B组清创后植入纳米羟基磷灰石/壳聚糖支架,C组清创后植入载万古霉素/PLGA缓释微球纳米羟基磷灰石/壳聚糖支架,D组清创后植入载万古霉素/PLGA缓释微球纳米羟基磷灰石/壳聚糖支架及自体红骨髓。治疗3个月后,通过X射线、病理苏木精-伊红染色评价骨缺损修复效果。结果与结论:(1)载万古霉素/PLGA缓释微球的纳米羟基磷灰石/壳聚糖支架,具有良好的生物力学性能及缓慢平稳释放万古霉素的能力;(2)治疗3个月后的X射线显示,A、B组胫骨近端仍见明显的缺损区、骨质破坏及骨膜反应;C组可见新生骨形成,缺损区稍模糊,但仍有缺损存在;D组可见新骨形成,缺损区模糊,密度稍增高,骨膜反应消失;(3)治疗3个月后的病理苏木精-伊红染色显示,A、B组骨小梁紊乱、破坏较多;C、D组骨小梁排列较为整齐,破坏较少,且D组骨小梁粗大,排列有序;(4)结果表明,载万古霉素/PLGA缓释微球的纳米羟基磷灰石/壳聚糖支架联合自体红骨髓修复兔慢性骨髓炎骨缺损效果良好。

生态产品价值实现机制的理论创新与实践探索

探索生态产品价值实现机制是践行“两山”理念,破解保护与发展矛盾的重要议题。本文首先剖析了生态产品的形成机理和价值特性,区分了生态产品的市场价值和非市场价值。其次,基于(准)公共产品视角,探究了生态产品的供给方式;进而从生产、交换、消费、分配各环节上,探讨了各类生态产品价值实现的共性诉求,认为生态产品市场价值依赖于市场交易手段实现,生态产品非市场价值则通过附着在物质产品之上或生态补偿手段实现;在此基础上,从产权管理、价值核算、生态产业化运营和资本化运作、多元化生态补偿等方面提出生态产品实现机制和制度保障。最后,针对制约生态产品价值实现的现实障碍,以丽水生态补偿和南平生态银行为例,探讨了生态产品价值实现的可行路径和改进方向。

“双碳”目标下低碳消费的作用机制和推进政策

落实碳达峰碳中和目标是一项涉及生产和生活方式变革的系统工程。围绕公众衣、食、住、行、用等生活领域,探究低碳消费的作用机制。低碳消费通过“直接减碳机制”或倒逼低碳生产的“间接减碳机制”助力碳达峰尽早实现,通过将人工与自然手段相结合的“保护机制”推动碳中和进程。基于需求效用论、外部性理论、消费行为论可知,低碳消费是多重心理动机的结果,易受多种因素影响,既需要硬性规制约束,又需要软性政策引导,消除低碳消费认知偏差,解决低碳消费外部性问题。梳理中国自“十一五”时期以来的低碳消费政策历程,并针对公众参与度较低、低碳消费市场不完善等困境,提出“十四五”期间应从参与主体、产品规范、市场培育、宣传教育、消费场景等方面进一步完善低碳消费的推进政策。

中国气候变化政策演进及阶段性特征

中国自1979年参加首届世界气候大会开始关注全球气候变化议题,到1992年成为《联合国气候变化框架公约》的缔约方,正式围绕应对气候变化建章建制,迄今已构建起较为完备的气候政策体系。当前,中国作为世界碳排放量排名第一的国家,正面临经济转型和减排的双重压力,站在新的历史方位,有必要总结已有气候政策的成效,明晰具有中国特色的气候治理方案。本文系统地梳理中国气候政策三十余年的演进历程和阶段性特征,解析国内减排行动和气候外交的变迁,总结中国气候治理经验,旨在为中国坚定减排信心、明确气候治理工作方向提供依据。中国气候政策取得了瞩目的阶段性成果,其经验在于对内统筹推进减缓与适应行动,将应对气候变化与经济社会可持续发展目标紧密结合;对外坚持与国际社会共建气候治理多边机制;未来中国应加快国内转型发展进程,以卓越的减排成效和先进的转型理念扮演好全球气候治理"引领者"的角色。

行政检查、行政约谈能提升平台规制的效果吗?--基于网约车平台的“大数据+准实验”研究

平台经济在我国经济社会发展全局中的地位和作用日益凸显,它为公众提供便捷、高效的同时,也蕴含着新的风险。如何防范化解风险,促进平台经济行稳致远的发展,从而更好地保护公众利益,是我国政府高度重视的问题。然而,既有研究尚未对政府如何在平台规制中发挥作用这一问题提供充分的论证与解释。围绕平台经济发展中的社会性风险这一议题,基于回应性规制理论下的威慑与遵从逻辑,研究采用“大数据+准实验”的设计思路,将网约车监管中的行政检查、行政约谈作为政策干预变量,以公众微博文本中挖掘的情感得分为结果变量,利用间断时间序列分析方法对政府规制效果进行检验。研究发现:(1)行政检查基于强制与惩罚对平台产生了威慑效果,行政约谈通过劝服与对话促成了平台的遵从行为,二者均能有效提升平台规制的效果,干预当期政策效应显著但不具有长效性;(2)行政检查、行政约谈的政策效应存在差异,规制手段强制力的高低对规制效果产生了不同程度的影响,威慑性规制的效果更为稳健。研究将全面的回应性规制框架扩展到平台规制这一新兴技术治理领域,丰富了回应性规制理论的本土化研究,为从公众评价的角度研究政策效果提供了新的思路。研究证明,行政约谈与行政检查的协同互补,能够形成更强大的政策合力,从而有利于风险的防范与治理,这为平台监管机制的完善提供了一定的政策启示。

Leaching behaviors of calcium and magnesium in ion-adsorption rare earth tailings with magnesium sulfate

The leaching behaviors of calcium and magnesium in the rare earth tailings leached with magnesium sulfate using deionized water,CaCl2 solution and lime water were investigated.Experimental data indicated that magnesium in the tailings was easy to be leached out since most of the magnesium was in the form of water-soluble phase.Most of calcium in the lime water was electrostatically adsorbed on the clay mineral of the tailings,and the water-soluble magnesium was also gradually converted into exchangeable phase because of back-adsorption of Mg2+on the clay mineral with increasing the pH values.When the liquid-to-solid ratio was 0.80,the contents of readily-available magnesium and calcium were 104.4−207.6 and 201.7−1426.3 mg/kg,respectively,which could meet the requirements for plants.These results suggest a promising route for the environmental remediation of ion-adsorption rare earth ore after in-situ leaching.

Distributed Periodic Event-Triggered Optimal Control of DC Microgrids Based on Virtual Incremental Cost

This article presents a distributed periodic eventtriggered(PET)optimal control scheme to achieve generation cost minimization and average bus voltage regulation in DC microgrids.In order to accommodate the generation constraints of the distributed generators(DGs),a virtual incremental cost is firstly designed,based on which an optimality condition is derived to facilitate the control design.To meet the discrete-time(DT)nature of modern control systems,the optimal controller is directly developed in the DT domain.Afterward,to reduce the communication requirement among the controllers,a distributed event-triggered mechanism is introduced for the DT optimal controller.The event-triggered condition is detected periodically and therefore naturally avoids the Zeno phenomenon.The closed-loop system stability is proved by the Lyapunov synthesis for switched systems.The generation cost minimization and average bus voltage regulation are obtained at the equilibrium point.Finally,switch-level microgrid simulations validate the performance of the proposed optimal controller.

Distributed Control of Multiple-Bus Microgrid With Paralleled Distributed Generators

A microgrid is hard to control due to its reduced inertia and increased uncertainties. To overcome the challenges of microgrid control, advanced controllers need to be developed.In this paper, a distributed, two-level, communication-economic control scheme is presented for multiple-bus microgrids with each bus having multiple distributed generators(DGs) connected in parallel. The control objective of the upper level is to calculate the voltage references for one-bus subsystems. The objectives of the lower control level are to make the subsystems' bus voltages track the voltage references and to enhance load current sharing accuracy among the local DGs. Firstly, a distributed consensusbased power sharing algorithm is introduced to determine the power generations of the subsystems. Secondly, a discrete-time droop equation is used to adjust subsystem frequencies for voltage reference calculations. Finally, a Lyapunov-based decentralized control algorithm is designed for bus voltage regulation and proportional load current sharing. Extensive simulation studies with microgrid models of different levels of detail are performed to demonstrate the merits of the proposed control scheme.

Adaptive Decentralized Output-Constrained Control of Single-Bus DC Microgrids

A single-bus DC microgrid can represent a wide range of applications. Control objectives of such systems include high-performance bus voltage regulation and proper load sharing among multiple distributed generators(DGs) under various operating conditions. This paper presents a novel decentralized control algorithm that can guarantee both the transient voltage control performance and realize the predefined load sharing percentages. First, the output-constrained control problem is transformed into an equivalent unconstrained one. Second, a two-step backstepping control algorithm is designed based on the transformed model for bus-voltage regulation. Since the overall control effort can be split proportionally and calculated with locally-measurable signals, decentralized load sharing can be realized. The control design requires neither accurate parameters of the output filters nor load measurement. The stability of the transformed systems under the proposed control algorithm can indirectly guarantee the transient bus voltage performance of the original system. Additionally, the high-performance control design is robust, flexible, and reliable. Switch-level simulations under both normal and fault operating conditions demonstrate the effectiveness of the proposed algorithm.

Spatial and Temporal Variations in Available Soil Nitrogen—A Case Study in Kobresia Alpine Meadow in the Qinghai-Tibetan Plateau, China

Elucidating the factors that determine the effects of temporal and spatial variation of nutrients is important for analyzing the characteristics of an ecosystem. The goal of this paper was to estimate how values obtained using a particular sampling approach correlated with the actual data for an entire plot. The mesh partition method was employed to divide an integrated observing field (IOF) located at the Haibei National Field Research Station of an alpine grassland ecosystem, China, into 25 subplots. Five of the 25 subplots were randomly selected for soil sampling and to determine the source of variations in soil nutrient content from 2001 to 2012. The results showed that, contributions of temporal and spatial variation in available nitrogen in the 0 - 10 cm soil layer accounted for 47.3% and 52.7%, respectively. The contribution of spatial variance was higher than that of temporal variance especially in the surface soil layers. The available soil nitrogen content in the alpine meadow was not obviously affected by fluctuations in rainfall and temperature. Increasing the number of samples could reduce calculation errors in measuring available soil nitrogen content, while collecting a reasonable number of samples can save time and labor.

Effect of vanadium carbide on commercial pure aluminum

The effect of vanadium carbide（VC） on the grain size of commercial pure aluminum was experimentally investigated by varying the content of VC, the holding time, and casting temperature. The refining efficiencies of VC and Al5Ti1 B were also compared. The refined samples of commercial pure aluminum were examined using optical microscopy, scanning electron microscopy（SEM） and energy-dispersive spectroscopy（EDS）. The results suggest that VC is a good refiner of commercial pure aluminum. The addition of only 0.3wt% VC can decrease the grain size of aluminum to 102 μm, whereas the casting temperature and holding time have little effect on the grain size. The refining efficiency of VC is better than that of Al5Ti1 B. The VC particles in molten aluminum act as nuclei and the grain refinement of aluminum alloys by VC particles is achieved via heterogeneous nucleation.

Directed Acyclic Graph Blockchain for Secure Spectrum Sharing and Energy Trading in Power IoT

Peer-to-peer(P2P)spectrum sharing and energy trading are promising solutions to locally satisfy spectrum and energy demands in power Internet of Things(IoT).However,implementation of largescale P2P spectrum sharing and energy trading confronts security and privacy challenges.In this paper,we exploit consortium blockchain and Directed Acyclic Graph(DAG)to propose a new secure and distributed spectrum sharing and energy trading framework in power IoT,named spectrum-energy chain,where a set of local aggregators(LAGs)cooperatively confirm the identity of the power devices by utilizing consortium blockchain,so as to form a main chain.Then,the local power devices verify spectrum and energy micro-transactions simultaneously but asynchronously to form local spectrum tangle and local energy tangle,respectively.Moreover,an iterative double auction based micro transactions scheme is designed to solve the spectrum and energy pricing and the amount of shared spectrum and energy among power devices.Security analysis and numerical results illustrate that the developed spectrum-energy chain and the designed iterative double auction based microtransactions scheme are secure and efficient for spectrum sharing and energy trading in power IoT.

Passability test and simulation of sand control string with natural gas hydrates completion in large curvature hole

To meet the requirements of marine natural gas hydrate exploitation,it is necessary to improve the penetration of completion sand control string in the large curvature borehole.In this study,large curvature test wells were selected to carry out the running test of sand control string with pre-packed screen.Meanwhile,the running simulation was performed by using the Landmark software.The results show that the sand control packer and screen can be run smoothly in the wellbore with a dogleg angle of more than 20°/30 m and keep the structure stable.Additionally,the comprehensive friction coefficient is 0.4,under which and the simulation shows that the sand control string for hydrate exploitation can be run smoothly.These findings have important guiding significance for running the completion sand control string in natural gas hydrate exploitation.

VGWO: Variant Grey Wolf Optimizer with High Accuracy and Low Time Complexity

The grey wolf optimizer(GWO)is a swarm-based intelligence optimization algorithm by simulating the steps of searching,encircling,and attacking prey in the process of wolf hunting.Along with its advantages of simple principle and few parameters setting,GWO bears drawbacks such as low solution accuracy and slow convergence speed.A few recent advanced GWOs are proposed to try to overcome these disadvantages.However,they are either difficult to apply to large-scale problems due to high time complexity or easily lead to early convergence.To solve the abovementioned issues,a high-accuracy variable grey wolf optimizer(VGWO)with low time complexity is proposed in this study.VGWO first uses the symmetrical wolf strategy to generate an initial population of individuals to lay the foundation for the global seek of the algorithm,and then inspired by the simulated annealing algorithm and the differential evolution algorithm,a mutation operation for generating a new mutant individual is performed on three wolves which are randomly selected in the current wolf individuals while after each iteration.A vectorized Manhattan distance calculation method is specifically designed to evaluate the probability of selecting the mutant individual based on its status in the current wolf population for the purpose of dynamically balancing global search and fast convergence capability of VGWO.A series of experiments are conducted on 19 benchmark functions from CEC2014 and CEC2020 and three real-world engineering cases.For 19 benchmark functions,VGWO’s optimization results place first in 80%of comparisons to the state-of-art GWOs and the CEC2020 competition winner.A further evaluation based on the Friedman test,VGWO also outperforms all other algorithms statistically in terms of robustness with a better average ranking value.

Electroactive barium titanate coated titanium scaffold improves osteogenesis and osseointegration with low-intensity pulsed ultrasound for large segmental bone defects

For large segmental bone defects,porous titanium scaffolds have some advantages,however,they lack electrical activity which hinders their further use.In this study,a barium titanate(BaTiO3)piezoelectric ceramic was used to modify the surface of a porous Ti6Al4V scaffold(pTi),which was characterized by scanning electron microscopy,energy dispersive spectroscopy,X-ray photoelectron spectroscopy,and roughness and water contact angle analyses.Low intensity pulsed ultrasound(LIPUS)was applied in vitro and in vivo study.The activity of bone marrow mesenchymal stem cells,including adhesion,proliferation,and gene expression,was significantly superior in the BaTiO3/pTi,pTi+LIPUS,and BaTiO3/pTi+LIPUS groups than in the pTi group.The activity was also higher in the BaTiO3/pTi+LIPUS group than in the BaTiO3/pTi and pTi+LIPUS groups.Additionally,micro-computed tomography,the mineral apposition rate,histomorphology,and the peak pull-out load showed that these scaffold conditions significantly enhanced osteogenesis and osseointegration 6 and 12 weeks after implantation in large segmental bone defects in the radius of rabbits compared with those resulting from the pTi condition.Consequently,the improved osteogenesis and osseointegration make the BaTiO3/pTi+LIPUS a promising method to promote bone regeneration in large segmental bone defects for clinical application.

Aggregation-induced emission polymers via reversible-deactivation radical polymerization Special Collection:Distinguished Australian Researchers

Aggregation-induced emission(AIE)is a unique phenomenon whereby aggregation of molecules induces fluorescence emission as opposed to the more commonly known aggregation-caused quenching(ACQ).AIE has the potential to be utilized in the large-scale production of AIE-active polymeric materials because of their wide range of practical applications such as stimuli-responsive sensors,biological imaging agents,and drug delivery systems.This is evident from the increasing number of publications over the years since AIE was first discovered.In addition,the evergrowing interest in this field has led many researchers around the world to develop new and creative methods in the design of monomers,initiators and crosslinkers,with the goal of broadening the scope and utility of AIE polymers.One of the most promising approaches to the design and synthesis of AIE polymers is the use of the reversible-deactivation radical polymerization(RDRP)techniques,which enabled the production of well-controlled AIE materials that are often difficult to achieve by other methods.In this review,a summary of some recent works that utilize RDRP for AIE polymer design and synthesis is presented,including(i)the design of AIE-related monomers,initiators/crosslinkers;the achievements in preparation of AIE polymers using(ii)reversible addition–fragmentation chain transfer(RAFT)technique;(iii)atom transfer radical polymerization(ATRP)technique;(iv)other techniques such as Cu(0)-RDRP technique and nitroxide-mediated polymerization(NMP)technique;(v)the possible applications of these AIE polymers,and finally(vi)a summary/perspective and the future direction of AIE polymers.

基于GMDH神经网络的智能多源自主导航方法

针对复杂受限、博弈对抗等场景下飞行器自主导航系统的“可重构性”需求,提出了一种基于GMDH神经网络的多源自主导航方法。利用GMDH神经网络的动态建模能力增强传统卡尔曼滤波器的状态估计矩阵,通过神经网络构建时变状态转移模型,预测并代替GNSS系统时间序列中的位置与速度信息,实现卫星拒止条件下的多源自主导航滤波器的平滑快速收敛,有效应对卫星信号中断情况下导航误差发散等难题,提高其应对复杂任务场景的自主判别与重构能力。仿真结果表明,相比于传统松组合导航和长短时记忆神经网络滤波优化算法,所提方法在卫星短时拒止条件下,速度精度提升了27.3%,位置精度提升了20.1%,为新一代国家综合PNT体系端侧自主导航系统设计提供参考。