Hierarchical porous onion-shaped LiMn<Subscript>2</Subscript>O<Subscript>4</Subscript> as ultrahigh-rate cathode material for lithium ion batteries

Spinel LiMn₂O₄ is a widely utilized cathode material for Li-ion batteries. However, its applications are limited by its poor energy density and power density. Herein, a novel hierarchical porous onion-like LiMn₂O₄(LMO) was prepared to shorten the Li⁺ diffusion pathway with the presence of uniform pores and nanosized primary particles. The growth mechanism of the porous onion-like LiMn₂O₄ was analyzed to control the morphology and the crystal structure so that it forms a polyhedral crystal structure with reduced Mn dissolution. In addition, graphene was added to the cathode (LiMn₂O₄/graphene) to enhance the electronic conductivity. The synthesized LiMn₂O₄/graphene exhibited an ultrahigh-rate performance of 110.4 mAh·g^–1 at 50 C and an outstanding energy density at a high power density, maintaining 379.4 Wh·kg^–1 at 25,293 W·kg^–1. Besides, it shows durable stability, with only 0.02% decrease in the capacity per cycle at 10 C. Furthermore, the (LiMn₂O₄/graphene)/graphite full-cell exhibited a high discharge capacity. This work provides a promising method for the preparation of outstanding, integrated cathodes for potential applications in lithium ion batteries.

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基于控制单元的流域水环境问题诊断方法研究

流域内水系的水质在空间和时间上往往有明显的时空变化特点,常规的基于断面达标的水质诊断方法容易忽略流域内污染负荷产生的时空特点。基于生态环境空间管控的理念,将流域干流水文过程与断面水质浓度变化相结合,提出了等标负荷历时曲线法的水环境问题诊断方法,该方法可以有效地识别出流域不同控制单元主要超标污染物及其污染来源。从某流域的应用评价结果来看:在流域河源及上游区域,超标时段集中在大流量的汛期,主要超标因子为总磷(TP),表明对于该流域上游及水系源头控制单元而言,农业等非点源污染是主要的污染来源;而对于入江河口区域,主要超标污染物是氨氮(NH_3-N),且为全时段超标,此控制单元的污染削减控制方案应将重点放在工业源和生活源上。     

一种城市道路照明的节能措施

着重讨论次干道及以下道路照明的节能问题,通过接在路灯回路里的时间继电器和中间继电器的控制器完成隔灯亮灯的功能,并和增加电力电缆控制隔灯亮灭的方法进行了技术经济比较,证明取得了较好的节能效果,最后还分析了这种方法存在的问题。     

连续结晶器积垢的化学清洗

通过对连续结晶器积垢成因的分析,提出了用纯碱和氯化钠溶液清洗的新方法．     

Maximum temperature rise of fire plume ejected out of the compartment window with a horizontal eave

This study focuses on the maximum temperature rise of fire plume ejected out of the compartment window with a horizontal eave. Based on the symmetry of ejected plume and pictures recorded by the cameras in the study, the shape of ejected thermal plume out of the window under the eave is suggest as an isosceles trapezoid, and the ejected thermal plume rising at the edge of the eave is assumed to be a rectangular fire source. The dimensions of the rectangular fire source are theoretically deduced for compartment fire process of different window geometry, width of eave, and heat release rate, according to the conservation of plume mass. The previous predictive model for plume temperature proposed by Quintiere is popularized to the ejected flame above an eave by including the dimensions of the rectangular fire source as well as the width of eave. The results would provide theoretical guidance to the application of fireproof eave in high-rise building for fire protection designs.     

甘肃省肃北县二段井地区遥感地质特征及金多金属找矿预测

甘肃省肃北县二段井地区属于北山造山带南带拾金坡-金场沟金、铜、铁和铅锌、银、稀有金属成矿带,具有良好的成矿条件和找矿潜力.该文利用日本ALOS遥感数据,完成遥感地质解译工作,采用美国Land-sat 8 OLI数据完成矿化蚀变信息的提取工作,并结合已有的地质矿产及物化探资料,对区内的成矿地质条件及找矿远景进行了分析预测...     

Phase partition and KPI-related process monitoring for batch processes using a novel canonical correlation analysis strategy

Key performance indicators (KPI)-related process monitoring has been of great significance to ensure product quality and economic benefits for batch processes. Considering that different phases exhibit different characteristics, one of the key issues is how to partition the whole batch process into different phases and characterize them separately by multiple phase models. In order to model and monitor batch processes more accurately and efficiently, a novel canonical correlation analysis (CCA) strategy is proposed in this paper. The phase partition algorithm is designed based on the joint canonical variable matrix (JCVM). Different from previous methods, it considers the time sequence of operation phases and can distinguish the phase switches from dynamics anomalies. Using this algorithm, phases are separated in order from a KPI-related perspective, revealing high correlation among variables. After phase partition, a novel multi-phase local neighbourhood standardization CAA (MPLNSCCA) method focusing on KPI is set up for online monitoring, which could further address the misclassification problems. The advantages of the proposed method are illustrated by two case studies, a penicillin simulation platform and an industrial application of Escherichia coli fermentation, respectively.     

寄生电感对低压增强型GaN HEMT开关行为的影响

寄生电感是影响功率管开关特性的重要因素之一,开关频率越高,寄生电感对低压增强型氮化镓高电子迁移率晶体管(GaN HEMT)的开关行为影响越深,使其无法发挥高速开关的性能优势。通过建立数学模型,理论分析了考虑各部分寄生电感后增强型GaN HEMT的开关过程,并推导了各阶段的持续时间和影响因素,然后通过建立双脉冲测试平台,对各部分寄生电感对开关特性的具体影响进行了实验验证。实验结果表明,寄生电感会使开关过程中的电流、电压出现振荡,影响开关速度和可靠性,并且各部分寄生电感对增强型GaN HEMT的开关过程影响程度不同,在实际PCB布局受到物理限制时,需要根据设计目标优化布局,合理分配各部分寄生电感以获得最优的开关性能。     

Mg-6Al-1Nd-1.5Gd合金的高温蠕变机制

采用高温蠕变装置,研究了Mg-6Al-1Nd-1.5Gd合金在150、175、200℃以及50、70、90 MPa条件下的高温压缩蠕变行为,分析合金在高温蠕变过程中的蠕变机制。结果表明,Mg-6Al-1Nd-1.5Gd合金的平均应力指数及蠕变激活能分别为4.64和73.87kJ/mol,其主要蠕变机制是由位错攀移和晶界扩散共同作用,合金的蠕变本构方程为:ε=1.877×10-8σ4.641exp[-73 865/(RT)];合金在高温蠕变过程中,微观组织中的位错密度逐渐增大,出现位错缠结及位错堆积,合金蠕变后的晶粒变得粗大,金属间化合物Al3Nd和Al3Gd在晶界上出现偏聚。     

一种控制系统串行口驱动程序的实现

控制系统中的通信是设计人员经常需要面对的问题,本文介绍了一种工业控制系统中串行口驱动程序的设计与实现。