基于水资源的工业绿色偏向型技术进步测度与分析

经济增长的"新常态"模式必然要求逐步提高全要素生产率对增长的贡献,这也是提升经济发展质量的内在要求;而其中,能兼顾资源环境约束的绿色技术进步对于提升经济长期可持续性发展的作用显得尤为重要。基于此,本文探究了兼顾水资源投入和水污染排放后,中国工业绿色偏向型技术进步的测度和分解问题及影响因素分析。利用中国大陆除西藏外30个省1999—2015年间工业投入产出数据,构建基于方向距离函数的绿色偏向型技术进步模型,采用参数与非参数回归相结合的方法,具体判断绿色技术偏向对要素投入、产出的影响以及技术进步的动态演进和区域分布特征。结果显示:(1)区域工业TFP基本处于持续增长状态,且其增长主要由绿色技术进步因素推动。(2)大部分省市多数年份仍倾向于过度使用水资源进行生产,高耗水特征明显;前期的产出偏向型技术进步加重了水污染物排放,直到"十一五"后期才逐步有利于减排。(3)东部地区技术进步更偏向于促进工业增长而抑制排放,中西部则倾向于排放更多污染物。(4)工业研发投入、治理水污染投资、工业劳动力受教育程度、用水价格及水资源储量等因素会对偏向型技术进步产生不同方向的影响。本文在兼顾水资源和水环境约束条件下,从原理上把技术进步分解为绿色投入偏向型技术进步和绿色产出偏向型技术进步两方面,甄别不同的技术偏向对投入要素和产出的影响,并实证应用于分地区工业水资源使用问题,为绿色偏向技术进步的量化测度提供了新的视角,亦为中国工业可持续性增长提供了政策启示。

移动机器人路径规划算法综述

为提高机器人路径规划的搜索速度,缩短搜索时间,总结归纳移动机器人在路径规划问题上的算法及其特点。首先回顾移动机器人发展历史,并对路径规划技术进行概述;其次对移动机器人路径规划进行分类总结,并从移动机器人对环境掌握情况的角度出发,将移动机器人路径规划分成全局规划和局部规划两类,然后对全局规划和局部规划的相关算法进行综述,同时对相关算法发展现状及优缺点进行总结。最后指出机器人路径规划技术在改进算法、混合算法、多机器人协作、复杂环境以及多维环境下进一步深入研究的未来发展趋势。

儿童早期发展的投资与干预:国际的实证依据

近十多年来,儿童早期健康、营养、社会保障、入学公平以及有质量的保育和教育逐渐受到全球的关注。儿童早期保育与教育已经纳入2030可持续发展目标之中。政府为幼儿制定全面的政策、为家长提供有质量的服务、提供必要的公共资金逐渐成为发展的紧迫要求。本文基于世界不同国家、不同政治经济和社会文化背景的实证依据,呈现对处境不利儿童及早干预的重要性,早期投资对个体和经济社会发展的益处,以及不同早期干预措施的影响力。进一步比较了当前儿童早期发展实际的和最佳的投资模式特征,介绍了近年来发展中国家儿童早期发展的实践项目及其干预研究结果。强调政府需要重视并衡量儿童早期保育与教育的质量,参照国际经验开展政策的制定工作。由于儿童早期发展项目的实施涉及到公共和私营部门的诸多利益相关方,需要建立支持儿童早期发展的制度架构,建立协调机制,促进政策的设计、制定、实施和评估。

我国幼儿园教师队伍建设中的资格及任用制度探讨

现行《中华人民共和国教师法》中,关于幼儿园教师入职、任用和发展等相关规定经25年的社会发展已滞后性凸显,亟待明确和完善。在启动《中华人民共和国教师法》修订的背景下,总结分析我国现行幼儿园教师资格及任用制度的现状及存在的问题,建议借鉴幼儿园教师资格与任用方面的国际经验,完善我国幼儿园教师资格及任用制度:提升幼儿园教师准入标准,提高师资队伍入职门槛;进一步完善教师资格认证制度;落实幼儿园教师定期注册制度;在幼儿园教师的任用标准与聘任制度上逐步走向法制化;建立和完善幼儿园教师的退出机制。

Mechanical and tribological performance of AlCr_(0.5)NbTa_(x)Ti_(4-x)(x=0,0.5,1)refractory high-entropy alloys

The tribological behavior of AlCr_(0.5)NbTa_(x)Ti_(4-x)(x=0,0.5,and 1)refractory high-entropy alloys was systematically investigated from room temperature to 800℃.The relationship between the alloy composition,microstructure,mechanical properties,and tribological performance was analyzed.The results show that all three alloys have a body-centered cubic(bcc)single-phase structure.The Ta addition enhances solid solution strengthening and increases the melting point that would resist high-temperature thermal softening.As a result,high-temperature strength is enhanced considerably,the coefficients of friction(COF)and wear rates of the alloys are reduced considerably at elevated temperatures,demonstrating excellent friction-reducing and anti-wear properties,e.g.,the COF and wear rate of AlCr_(0.5) NbTaTi_(3) alloy at 800℃ are 0.34 and 4.40×10^(-7) mm^(3) N^(-1) m^(-1),respectively.The excellent wear resistance at high temperatures can be attributed to the formation of an oxide-tribo layer(Ta_(2)O_(5) and TiO_(2))with ultrafine-grained layers and good high-temperature mechanical properties.

Coordinated Secondary Control for Autonomous Hybrid Three-port AC/DC/DS Microgrid

This paper presents a coordinated secondary control(CSC)strategy for distributed power management for an autonomous hybrid three-port AC/DC/DS microgrid.The proposed CSC is on top of a generalized primary control(GPC),which consists of local power sharing(LPS)control within an individual AC or DC subgrid,global power sharing(GPS)control throughout the AC/DC subgrids,and storage power sharing(SPS)control in a distributed storage(DS)network.The CSC along with the GPC uses the local frequency/voltage deviations and offers decentralized power management with enhanced overall reliability.To eliminate the inherent frequency/voltage deviations in GPC and restore to their nominal values,a secondary control is normally applied to all distributed generators(DGs),which would degrade the performance of decentralized power management.To overcome this concern,a CSC strategy is proposed to concurrently restore frequency/voltage and re-establish a distributed power management by means of limited information exchange through the low-bandwidth communication links.The proposed control scheme has been verified by both simulations and controller hardware-in-the-loop(CHIL)experiments in an OPAL-RT digital simulator system.

The determining role of carbon addition on mechanical performance of a non-equiatomic high-entropy alloy

The mechanical properties and deformation mechanism of a C-doped interstitial high-entropy alloy(i HEA)with a nominal composition of Fe_(49.5)Mn_(29.7)Co_(9.9)Cr_(9.9)C_(1)(at.%)were investigated.An excellent combination of strength and ductility was obtained by cold rolling and annealing.The structure of the alloy is consisted of FCC matrix and randomly distributed Cr_(23)C_(6).For gaining a better understanding of deformation mechanism,EBSD and TEM were conducted to characterize the microstructure of tensile specimens interrupted at different strains.At low strain(2%),deformation is dominated by dislocations and their partial slip.With the strain increase to 20%,deformation-driven athermal phase transformation and dislocations slip are the main deformation mechanism.While at high strain of 35%before necking,deformation twins have been observed besides the HCP phase.The simultaneous effect of phase transformation(TRIP effect)and mechanical twins(TWIP effect)delay the shrinkage,and improve the tensile strength and plasticity.What's more,compared with the HEA without C addition,the yield strength of the C-doped i HEA has been improved,which can be attributed to the grain refinement strengthening and precipitation hardening.Together with the lattice friction and solid solution strengthening,the theoretical calculated values of yield strength match well with the experimental results.

Influence of cooling rate on phase transformation and precipitation behavior of Ti-bearing steel in continuous cooling process

The influence of cooling rate on microstructural evolution and precipitation behavior in Ti,Ti–Nb and Ti-Mo low-carbon steels during the continuous cooling process was studied by dilatometer method,optical microscopy,and transmission electron microscopy.The results indicated that austenite transformation temperature decreased with the increasing cooling rate in three steels.The addition of Nb and Mo promoted bainite and martensite transformation and improved the hardenability of steels.In addition,precipitates formed in deformed austenite and ferrite can be observed simultaneously.Deformation in the austenite non-recrystallization zone can introduce a large number of deformation bands,and then,the precipitates preferentially nucleated in these deformation bands.In the following process,randomly distributed precipitates and interphase precipitates will be formed in ferrite.The precipitates formed in deformed austenite obey Kurdjumov-Sachs orientation relationship with the matrix,while the precipitates formed in ferrite obey Baker-Nutting orientation relationship with the matrix.The addition of Nb and Mo in Ti-bearing steels decreased the precipitates size and increased the number density of precipitates and then improved the precipitation hardening.And the effect of Mo addition is more obvious than that of Nb addition.

KHK-A promotes fructose-dependent colorectal cancer liver metastasis by facilitating the phosphorylation and translocation of PKM2

Excessive fructose diet is closely associated with colorectal cancer(CRC)progression.Nevertheless,fructose’s specific function and precise mechanism in colorectal cancer liver metastasis(CRLM)is rarely known.Here,this study reported that the fructose absorbed by primary colorectal cancer could accelerate CRLM,and the expression of KHK-A,not KHK-C,in liver metastasis was higher than in paired primary tumors.Furthermore,KHK-A facilitated fructose-dependent CRLM in vitro and in vivo by phosphorylating PKM2 at Ser37.PKM2 phosphorylated by KHK-A inhibited its tetramer formation and pyruvic acid kinase activity but promoted the nuclear accumulation of PKM2.EMT and aerobic glycolysis activated by nuclear PKM2 enhance CRC cells’migration ability and anoikis resistance during CRLM progression.TEPP-46 treatment,targeting the phosphorylation of PKM2,inhibited the pro-metastatic effect of KHK-A.Besides,c-myc activated by nuclear PKM2 promotes alternative splicing of KHK-A,forming a positive feedback loop.