Solid-state NMR studies of sulfonated SBA-15 and the synergistic catalysis of fructose into 5-hydroxymethylfurfural with dimethyl sulfoxide

Sulfonic acid functionalized mesoporous SBA-15 was prepared using the grafting method.The structure and acid properties were comprehensively characterized using multi-nuclear and quantitative probe molecule solid-state NMR(SSNMR),together with powder X-ray diffraction(XRD),scanning electron microscope(SEM),transmission electron microscopy(TEM),N2 adsorption-desorption techniques.Its catalytic performance in the conversion of fructose to 5-hydroxymethylfurfural(HMF)in dimethyl sulfoxide(DMSO)was studied.Catalyst dosage,reaction time,reaction temperature and solvent effect have been investigated.A high yield of HMF up to 93%was obtained at a relatively low temperature of 373 K for 180 min.The Brønsted acid of SBA-15_SO3H together with the solvent DMSO was found to synergistically catalyze the reaction.The catalyst preserved most of its activity after five times reuse and the catalytic activity can be recovered by H2O2 process.

Recent advances on surface metal hydrides studied by solid-state nuclear magnetic resonance spectroscopy

Metal hydrides (MeH) on solid surfaces, i.e., surface MeH, are ubiquitous but criticalspecies in heterogeneous catalysis, and their intermediate roles have been proposed innumerous reactions such as (de)hydrogenation and alkanes activation, etc., however, thedetailed spectroscopic characterizations remain challenging. Solid-state nuclear magnetic resonance (ssNMR) spectroscopy has become a powerful tool in surface studies, asit provides access to local structural characterizations at atomic level from multipleviews, with comprehensive information on chemical bonding and spatial structures. Inthis review, we summarized and discussed the latest research developments on thesuccessful application of ssNMR to characterize surface MeH species on solid catalystsincluding supported single-site heterogeneous catalysts, bulk metal oxides and metalmodified zeolites. We also discussed the opportunities and challenges in this field, aswell as the potential application/development of state-of-the-art ssNMR technologies toenable further exploration of metal hydrides in heterogeneous catalysis.

DIR:Dynamic Request Interleaving for Improving the Read Performance of Aged Solid-State Drives

Triple-level cell(TLC)NAND flash is increasingly adopted to build solid-state drives(SSDs)for modern computer systems.While TLC NAND flash effectively improves storage density,it faces severe reliability issues;in partic-ular,the pages exhibit different raw bit error rates(RBERs).Integrating strong low-density parity-check(LDPC)code helps to improve reliability but suffers from prolonged and proportional read latency due to multiple read retries for worse pages.The straightforward idea is that dispersing page-size data across several pages in different types can achieve a low-er average RBER and reduce the read latency.However,directly implementing this simple idea into flash translation lay-er(FTL)induces the read amplification issue as one logic page residing in more than one physical page brings several read operations.In this paper,we propose the Dynamic Request Interleaving(DIR)technology for improving the performance of TLC NAND flash-based SSDs,in particular,the aged ones with large RBERs.DIR exploits the observation that the la-tency of an I/O request is determined,without considering the queuing time,by the access of the slowest device page,i.e.,the page that has the highest RBER.By grouping consecutive logical pages that have high locality and interleaving their encoded data in different types of device pages that have different RBERs,DIR effectively reduces the number of read re-tries for LDPC with limited read amplification.To meet the requirement of allocating hybrid page types for interleaved data,we also design a page-interleaving friendly page allocation scheme,which splits all the planes into multi-plane re-gions for storing the interleaved data and single-plane regions for storing the normal data.The pages in the multi-plane re-gion can be read/written in parallel by the proposed multi-plane command and avoid the read amplification issue.Based on the DIR scheme and the proposed page allocation scheme,we build DIR-enable FTL,which integrates the proposed schemes into the FTL with some modifications.Our experimental results show that adopting DIR in aged SSDs exploits nearly 33%locality from I/O requests and,on average,reduces 43%read latency over conventional aged SSDs.

Pinpointing and scheduling access conflicts to improve internal resource utilization in solid-state drives

Modern solid-state drives (SSDs)are integrating more internal resources to achieve higher capacity.Parallelizing accesses across internal resources can potentially enhance the performance of SSDs.However,exploiting parallelism inside SSDs is challenging owing to real-time access conflicts.In this paper,we propose a highly parallelizable I/O scheduler (PIOS)to improve internal resource utilization in SSDs from the perspective of I/O scheduling.Specifically, we first pinpoint the conflicting flash requests with precision during the address translation in the Flash Translation Layer (FTL).Then,we introduce conflict eliminated requests (CERs)to reorganize the I/O requests in the device-level queue by dispatching conflicting flash requests to different CERs.Owing to the significant performance discrepancy between flash read and write operations,PIOS employs differentiated scheduling schemes for read and write CER queues to always allocate internal resources to the conflicting CERs that are more valuable.The small dominant size prioritized scheduling policy for the write queue significantly decreases the average write latency.The high parallelism density prioritized scheduling policy for the read queue better utilizes resources by exploiting internal parallelism aggressively.Our evaluation results show that the paralle/izable I/O scheduler (PIOS)can accomplish better SSD performance than existing I/O schedulers implemented in both SSD devices and operating systems.

Detection of Multi-dimensional Driving Forces of Public Environmental Concern in China:Based on Spatial Heterogeneity Perspectives

Public environmental concern(PEC)is an important bottom-up force in building an environmentally sustainable society.Guided by attitude theory,this paper innovatively constructed a PEC evaluation index system,while introducing entropy weighted-TOPSIS(Technique for Order Preference by Similarity to Ideal Solution)to realize the assessment of PEC.Exploratory spatial data analysis was used to portray the spatio-temporal evolution patterns of PEC in 362 Chinese cities at prefecture-level and above from 2011 to 2018.Furthermore,the Geodetector model was performed to identify the multi-dimensional determinants of PEC from the perspective of spatial heterogeneity.The results indicated that:1)PEC in China exhibited a fluctuating upward trend,consistent with the spatial distribution law of‘Heihe-Tengchong Line’and‘Bole-Taipei Line’;2)the driving effect of each factor varied dynamically,but in general,economic development level,population size,industrial wastewater,and education level were the dominant driving factors explaining the spatial variation of PEC;3)risk detection revealed that four factors,government environmental regulations,PM_(2.5),vegetation coverage,and natural resource endowment,had nonlinear effects on PEC;4)the interactions between factors all demonstrated an enhancement in explaining the spatial differentiation of PEC.PEC was driven by the comprehensive interaction of four-dimensional factors of economy,society,pollutant emissions,and ecology.Among them,population agglomeration accompanied by a high level of regional economy and information technology can explain the increase in PEC to the greatest extent.

SoftSSD:enabling rapid flash firmware prototyping for solid-state drives

Recently,solid-state drives(SSDs)have been used in a wide range of emerging data processing systems.Essentially,an SSD is a complex embedded system that involves both hardware and software design.For the latter,firmware modules such as the flash translation layer(FTL)orchestrate internal operations and flash management,and are crucial to the overall input/output performance of an SSD.Despite the rapid development of new SSD features in the market,the research of flash firmware has been mostly based on simulations due to the lack of a realistic and extensible SSD development platform.In this paper,we propose SoftSSD,a software-oriented SSD development platform for rapid flash firmware prototyping.The core of SoftSSD is a novel framework with an event-driven programming model.With the programming model,new FTL algorithms can be implemented and integrated into a full-featured flash firmware in a straightforward way.The resulting flash firmware can be deployed and evaluated on a hardware development board,which can be connected to a host system via peripheral component interconnect express and serve as a normal non-volatile memory express SSD.Different from existing hardware-oriented development platforms,SoftSSD implements the majority of SSD components(e.g.,host interface controller)in software,so that data flows and internal states that were once confined in the hardware can now be examined with a software debugger,providing the observability and extensibility that are critical to the rapid prototyping and research of flash firmware.We describe the programming model and hardware design of SoftSSD.We also perform experiments with real application workloads on a prototype board to demonstrate the performance and usefulness of SoftSSD,and release the open-source code of SoftSSD for public access.

Asurvey on design and application of open-channel solid-state drives

Compared with traditional solid-state drives(SSDs),open-channel SSDs(OCSSDs)expose their internal physical layout and provide a host-based flash translation layer(FTL)that allows host-side software to control the internal operations such as garbage collection(GC)and input/output(I/O)scheduling.In this paper,we comprehensively survey research works built on OCSSDs in recent years.We show how they leverage the features of OCSSDs to achieve high throughput,low latency,long lifetime,strong performance isolation,and high resource utilization.We categorize these efforts into five groups based on their optimization methods:adaptive interface customizing,rich FTL co-designing,internal parallelism exploiting,rational I/O scheduling,and efficient GC processing.We discuss the strengths and weaknesses of these efforts and find that almost all these efforts face a dilemma between performance effectiveness and management complexity.We hope that this survey can provide fundamental knowledge to researchers who want to enter this field and further inspire new ideas for the development of OCSSDs.

A Coaching Program for Recently Licensed Young Drivers in the Netherlands： Which Drivers Are Attracted？

In line with European developments, a Dutch second phase coaching program, referred to as the DX- （Driver Xperience） program, was developed for young novice drivers to counteract their high accident risk. More specifically, the aim of the DX-program was to enable young drivers to make responsible decisions and develop positive attitudes regarding four levels of the driving task： combining life style and driving, planning and navigation, participating in different traffic situations and handling the vehicle. In this paper, the design principles of the program are described. The empirical study focused on the entry characteristics of the participating young drivers （n = 3,117） as compared to a reference group of young drivers （n = 345）. Results show that the DX-program attracted young drivers that, in some respects, showed a more risky profile than average young drivers in terms of speed violations, anger and the number of fines. In addition, four groups of participants with sharply differing driving styles could be distinguished. Implications for educational design and follow-up research are discussed within the theoretical framework of self-regulated learning.

公众感知下重大传染病疫情冲击对社区韧性驱动因子独立、耦合作用及区域异质性分析

目的:探究公众感知下重大传染病疫情冲击对社区韧性驱动因子独立、耦合作用及区域特征,为后续精准施策提供理论依据。方法:采用网络调查法在我国东、中、西部各选一个省会城市展开调查,运用地理探测器和ESDA对社区韧性驱动因子进行探测并比较区域异质性特征。结果:政府公信力(0.322)、应急物品准备情况(0.297)是社区韧性的主导因子;任意两因子耦合对社区韧性的解释力均显著增强;各驱动因子对社区韧性的影响在空间上存在差异性,且“风险意识”“政府公信力”“家庭应急计划”是造成区域异质性的关键因子。结论:重大传染病疫情冲击下的社区韧性是多因子耦合作用的结果,多因子耦合对社区韧性的复杂影响需要多部门、多阶段、多机制因地制宜采取差异化的举措,全方位提升社区韧性。

考虑时延的异质协作车队事件触发控制研究

针对目前研究较少考虑车辆混行造成的异质问题与时延问题,本文提出了一种具有时延的异质协作式自动驾驶车队事件触发控制方法 .首先,建立了考虑混行的异质车辆时延模型;其次,基于PID(proportional-integral-derivative)控制与模型预测控制(MPC),设计了不同模式下的事件触发控制器;然后,在城市和紧急情况下,对所提出的控制器进行了仿真分析;最后,基于Jetson Nano模型车进行了实车实验.仿真与实验结果表明,所提出的事件触发控制方法能够在不同情况下更好地权衡控制精度与计算速度间的矛盾.在带有通信时延的紧急情况下,仍能够保持较低的误差.

基于改进NaSch模型的网联异质交通流特性分析

为研究智能网联环境下异质交通流演变规律,设计典型场景驾驶模拟实验,采集传统车辆(human driven vehicle,HDV)与智能网联车辆(connected vehicle,CV)驾驶行为特征指标,对异质交通流关键参数进行分析和标定;构建考虑HDV与CV驾驶行为差异的异质交通流元胞自动机模型;并基于改进的NaSch模型进行仿真实验,解析智能网联环境下交通流基本图,分析异质交通流特性。研究结果表明:较于HDV,CV驾驶员捕捉道路信息和反应时间提升约11.4%;自由流状态下,CV车速比HDV车速提升了7.4%,且同一车速下安全跟驰距离缩短了18.2%;随着CV所占比例由20%增至80%,交通流基本图显示交通流平均车速显著提升,交通流率增加,时空轨迹图显示局部拥堵状况明显改善。

近十年哈尔滨市区县级LUCC时序演变及驱动机制分析

针对哈尔滨市土地利用的定量论证问题,从区县尺度分析多时段用地转化特征动态演变有助于得出更精细的结果,为地方政府部门和合理制定规划政策提供理论支持。本文采用2014—2022年哈尔滨市区县各项遥感影像数据,结合GDP、人口、DEM、坡度、气温、降水等影响因子数据信息,离散化后用土地覆被转移矩阵分析哈尔滨市土地利用覆被类型变化情况,引入地理探测器用单因子贡献率分析和多因子交互贡献率分析方法,探究了哈尔滨市近十年的用地变化的贡献度,综合分析了区县级土地利用时序演变特征及LUCC时序演变的多因子协同驱动机制,多因子交互贡献率对土地覆盖空间分布影响力体现为哈尔滨市土地利用的整体健康和可持续发展。

基于多源异构信息融合的采摘机械臂驱动控制研究

[目的]为了准确感知采摘机械臂的作业信息,提高驱动控制精度,需要对多自由度采摘机械臂的驱动控制模块进行优化设计。[方法]本研究将采摘机械臂各关节自由度、运动学以及动力学原理融合到设备结构中,完成了多自由度采摘机械臂等效模型的构建。基于构建的等效模型,确定多源传感器设备的安装位置,利用内部安装的传感器设备对机械臂的实时运行信息进行采集,获取位姿信息。同时,根据传感器的空间位置及其相互之间的作用进行信息分群,得出信息级融合结果,以此作为特征级信息融合结果的输入值,提取多源异构信息特征,并通过特征匹配完成融合操作,由此得出任意时刻采摘机械臂运行参数的检测结果。[结果]结合给定的采摘任务,计算采摘机械臂所需的驱动动力以及位姿数据,通过与当前数据的比对确定驱动控制量,利用装设的驱动控制器生成可执行的控制指令,完成驱动控制。与2种对照方法进行的对比试验显示,基于多源异构信息融合的驱动控制方法采摘机械臂的位置控制误差降低约25 mm,姿态角与驱动力控制误差分别降低了0.22°和6.32 mm,得出的控制数据更精准。[结论]由于多源异构信息融合技术能够发挥多种数据的优势,获取到更全面、更准确的位姿信息和控制数据,能够实现对目标果实的精准采摘,从而降低了采摘工作对果实的伤害,具有明显的对比优势和应用价值。

企业异质性视角下的文化产业集聚动力分析——基于藏羌彝走廊数据的实证研究

基于集聚经济理论、企业异质性理论、选择效应理论等构建藏羌彝走廊文化产业空间集聚动力理论框架,通过实证分析探析各动力因子对文化产业集聚的影响。结果表明:藏羌彝走廊文化产业集聚由基础设施共享、知识溢出、产业匹配、选择效应四大动力因子在不同程度上共同发挥作用,其中人力资本、研发支出、金融产业、信息产业、人力资源禀赋受到企业异质性的调节作用对文化产业集聚呈现出显著正向的影响,并且调节变量在不同水平时,各动力因子对文化产业集聚的影响幅度具有差异性。基础设施发达程度和市场规模,这两种动力因子未受到企业异质性的调节作用。

城市居民生活碳排放及影响因素的时空异质性

基于地图可视化、空间自相关、标准差椭圆和空间马尔科夫链探究中国2006~2020年城市居民生活碳排放的时空特征,并采用时空地理加权模型(GTWR)实证考察城市居民生活碳排放影响因素的时空异质性.结果显示:中国城市居民生活碳排放逐年增长,年均增长率为10.12%,但增速逐渐放缓;呈现东高西低的空间差异特征,且在样本后期呈现逐渐收敛态势.城市居民生活碳排放水平的空间分布呈现显著的空间聚集特征;标准差椭圆呈现向心集聚的趋势,且分布重心逐渐向西南移动,累计迁移了68.97km;居民生活碳排放的动态演进受到邻地城市碳排放水平的影响.各影响因素存在明显的时空异质性.时间趋势上,人口密度、经济发展、对外开放和产业结构在大部分城市促进碳排放,但影响力逐年减弱;技术投入和环境规制则降低碳排放,且影响力逐年增强;空间分布上,人口密度、经济发展和对外开放在南部的影响力更强,而技术投入、产业结构和环境规制的影响力在东部更强.

基于价值评估的环渤海地区生境质量时空演变与驱动力分析

利用环渤海2000—2020年土地利用产品、耦合生态系统服务价值模型、生态系统活力指数和InVEST生境质量模型评估环渤海海岸带地区生境质量的时空演化格局,采用地理探测器模型对生境时空演化进行驱动因子探测和交互作用分析。结果表明:2000—2020年环渤海地区整体生境质量等级处于中等且呈持续上升趋势,其中大连市、营口市、葫芦岛市和秦皇岛市生境质量较高;2000、2010、2020年环渤海地区生境质量处于中等等级面积占比依次为53%、57.4%、58.3%,等级由低、较低等级转化为中等等级的面积占比较大;2000—2020年环渤海地区生境质量变化主要受气温、高程、降水、路网密度和植被覆盖率等因子的影响,其中降水、气温和高程的影响程度较强,因子交互呈现双因子增强和非线性增强两种复合增强结果。研究结果可为海岸带地区生境修复、土地利用规划提供参考。

城市景观格局演变驱动因子及其特征研究综述

识别城市景观格局演变的驱动因子,是更好地理解城市景观动态格局、过程及其影响的关键,对于城市景观格局优化与预测、城市空间规划和政策制定等均至关重要。系统梳理了城市景观格局演变的驱动因子;归纳了城市景观格局变化驱动因子定量分析模型,包括基于经验的统计模型和基于过程的动态模型;阐明了全球、国家、城市群和城市等不同尺度下城市景观格局演变驱动因子的时空和尺度异质性特征,以及不同驱动因子的直接和间接效应。提出了城市景观格局演变驱动因子的未来研究方向。

洞庭湖流域碳储量的时空异质性及驱动力分析

基于遥感反演和模型修正法,动态分析1980~2020年洞庭湖流域生态系统碳储量的时空分布特征,并借助碳储量贡献率和最优参数地理探测器,量化分析生态系统相互转换以及自然-社会-政策环境对碳储量时空异质性的驱动机制.结果表明:40a来洞庭湖流域及其子流域碳储量先降后升,整体增长262.81Tg,呈现由东-南-西三面向中部、北部逐级递减的“马蹄形”格局;生态系统相互转换推动洞庭湖流域碳储量增长了23.66Tg,其中农田、森林和城镇生态系统间的相互转换主导碳储量变化;洞庭湖流域及其子流域碳储量的时空异质性主要受社会环境和政策环境的协同影响,其中生境质量和人口密度是主导因素.由于存在增强效应和差异化特征,使得双因子交互作用的影响更强烈.为提高生态系统固碳能力,应加快完善洞庭湖流域的生态系统结构,因地制宜构建生态与社会的良性互动关系.

河北省祥云湾人工鱼礁区网采浮游植物群落结构的 时空变化特征及其与关键环境因子的关系

为探究河北省祥云湾人工鱼礁区浮游植物群落结构特征的时空变化规律,明确人工鱼礁区建设对浮游植物的养护效果及其与环境因子的关系,于2021年5月、8月、11月和2022年1月对祥云湾人工鱼礁区及对照区海域开展了网采浮游植物和关键环境因子季度调查。结果表明,4个季度共发现浮游植物3门39属70种,其中硅藻种类数最多(78.6%);浮游植物丰度呈现显著季节变化,夏、秋季丰度最高,2处人工鱼礁区浮游植物的年平均丰度为313.5×10^(4) cells/m^(3),是对照区浮游植物丰度的1.4倍;除春季外,人工鱼礁区浮游植物的丰富度指数、多样性指数和均匀度指数均高于对照区,且礁区春-夏和夏-秋季节礁区优势种更替率低于对照区,表明人工鱼礁区群落结构相比对照区更稳定;人工鱼礁区浮游植物主要类群的生物增量指数为0.9~3.6,特别是硅藻类群的生物增量指数平均达到1.8;Pearson相关性分析显示,浮游植物丰度主要受TP、TN、NH_(4)-N、NO_(3)-N和DIP的影响,且各季节之间存在显著差异。研究表明,人工鱼礁建设对浮游植物具有良好的养护效果,且养护效果主要与营养盐的时空变化密切相关。

“双碳”目标下欠发达地区碳排放效率时空演变与驱动因素——超效率SBM模型测度与GTWR模型的异质性分析

在“双碳”目标约束下,欠发达地区的传统高碳经济增长模式难以为继,如何在保持经济稳步发展的同时减少碳排放是欠发达地区面临的重要挑战。本文基于超效率SBM模型测度典型欠发达地区2006—2020年间的碳排放效率,探究了碳排放效率的时空演变特征,采用空间面板计量模型测度碳排放效率影响因素,运用GTWR模型研究驱动因素异质性。研究表明:欠发达地区碳排放效率高-高集聚区表现出极化效应,而低-低集聚区呈现溢出效应;人口规模、技术进步与经济发展是影响碳排放效率的主要驱动因素,碳排放效率受自身滞后效应影响;驱动因素存在时空异质性特征,经济发展水平较低地区存在环境“逐底”竞争效应,大多数城市的人口集聚效应逐渐增强,技术进步呈现“学习效应”。因此,应当推进区域间协同治理碳污染问题,因地制宜实施低碳发展战略,助力欠发达地区实现绿色发展。