Temperature-dependent photoluminescence on organic inorganic metal halide perovskite CH3NH3Pb I3-xClx prepared on ZnO/FTO substrates using a two-step method

Temperature-dependent photoluminescence characteristics of organic-inorganic halide perovskite CH3NH3Pb I3-xClx films prepared using a two-step method on ZnO/FTO substrates were investigated. Surface morphology and absorption characteristics of the films were also studied. Scanning electron microscopy revealed large crystals and substrate coverage. The orthorhombic-to-tetragonal phase transition temperature was-140 K. The films＇ exciton binding energy was 77.6 ± 10.9 meV and the energy of optical phonons was 38.8 ± 2.5 meV. These results suggest that perovskite CH3NH3Pb I（3-x）Clx films have excellent optoelectronic characteristics which further suggests their potential usage in perovskitebased optoelectronic devices.

Applying the Dynamic Two-Step Method to Forecast Remaining Oil Distribution of Lower Series ,Xiaermen Oilfield

The distribution of remaining oil is often described qualitatively. The remaining oil distributed in the whole reservoir is calculated according to the characteristics of the space distribution of the saturation of remaining oil. Logging data are required to accomplish this. However, many such projects cannot be completed. Since the old study of remaining oil distribution could not be quantified efficiently, the ＂dynamic two-step method＂ is presented. Firstly, the water cut of every flow unit in one well at one time is calculated according to the comprehensive water cut of a single well at one time. Secondly, the remaining oil saturation of the flow unit of the well at one time is calculated based on the water cut of the flow unit at a given time. The results show that ＂dynamic two-step method＂ has characteristics of simplicity and convenience, and is especially suitable for the study of remaining oil distribution at high water-cut stage. The distribution of remaining oil presented banding and potato form, remaining oil was relatively concentrated in faultage neighborhood and imperfect well netting position, and the net thickness of the place was great. This proposal can provide an effective way to forecast remaining oil distribution and enhance oil recovery, especially applied at the high water-cut stage.

Forming Mechanism of Gaseous Defect in Ti-48Al-2Cr-2Nb Exhaust Valves Formed with Permanent Mold Centrifugal Casting Method

A method combining theoretical analysis with experiment is adopted and the flowing process of Ti-48A1-2Cr-2Nb alloy melt poured in a permanent mould during the centrifugal casting process has been analyzed. A mathematical model of the filling process is established and the forming mechanism of internal gaseous defect is summarized. The results of calculation show that the melt fills the mould with varying cross-section area and inclined angle. The filling speed of the cross-section is a function of filling time. The cross-section area is directly proportional to the filling speed and the inclined angle is inversely proportional to the filling speed at a given rotating speed of the platform. Both of them changes more obvious near the mould entrance. The gaseous defect can be formed in several ways and the centrifugal field has an important influence on the formation of the defect. In addition, the filling process in centrifugal field has been verified by wax experiments and the theoretical analysis are consistent with experimental results.

Application of Space-time Conservation Element and Solution Element Method in Intake and Exhaust Flows of High Power Density Diesel Engine

A one-dimensional pipe flow model of single-cylinder diesel engine is established to investigate the intake and exhaust flow characteristics of diesel engine in the condition of high power density(HPD).A space-lime conservation element and solution element(CE/SE)method is used to derive the discrete equations of the partial differential equation for the intake and exhaust systems.The performance parameters of diesel engine with speed of 2100 r/min are simulated.The simulated results are in accordance with the experimental data.The effect of increased power density on charging coefficient is analyzed using a validated model.The results show that the charging coefficient is slowly improved with the increase in intake pressure,and is obviously reduced with the increase in engine speed.

The convergence ball and error analysis of the two-step Secant method

Under the assumption that the nonlinear operator has Lipschitz continuous divided differences for the first order,we obtain an estimate of the radius of the convergence ball for the two-step secant method.Moreover,we also provide an error estimate that matches the convergence order of the two-step secant method.At last,we give an application of the proposed theorem.

Application of dual reciprocity boundary element method to predict acoustic attenuation characteristics of marine engine exhaust silencers

In marine engine exhaust silencing systems, the presence of exhaust gas flow influences the sound propagation inside the systems and the acoustic attenuation performance of silencers. In order to investigate the effects of three-dimensional gas flow and acoustic damping on the acoustic attenuation characteristics of marine engine exhaust silencers, a dual reciprocity boundary element method (DRBEM) was developed. The acoustic governing equation in three-dimensional potential flow was derived first, and then the DRBEM numerical procedure is given. Compared to the conventional boundary element method (CBEM), the DRBEM considers the second order terms of flow Mach number in the acoustic governing equation, so it is suitable for the cases with higher Mach number subsonic flow. For complex exhaust silencers, it is difficult to apply the single-domain boundary element method, so a substructure approach based on the dual reciprocity boundary element method is presented. The experiments for measuring transmission loss of silencers are conducted, and the experimental setup and measurements are explained. The transmission loss of a single expansion chamber silencer with extended inlet and outlet were predicted by DRBEM and compared with the measurements. The good agreements between predictions and measurements are observed, which demonstrated that the derived acoustic governing equation and the DRBEM numerical procedure in the present study are correct.

Solution of Nonlinear Integro Differential Equations by Two-Step Adomian Decomposition Method (TSAM)

The Adomian decomposition method (ADM) can be used to solve a wide range of problems and usually gets the solution in a series form. In this paper, we propose two-step Adomian Decomposition Method (TSAM) for nonlinear integro-differential equations that will facilitate the calculations. In this modification, compared to the standard Adomian decomposition method, the size of calculations was reduced. This modification also avoids computing Adomian polynomials. Numerical results are given to show the efficiency and performance of this method.

An Adaptive Sequential Replacement Method for Variable Selection in Linear Regression Analysis

With the rapid development of DNA technologies, high throughput genomic data have become a powerful leverage to locate desirable genetic loci associated with traits of importance in various crop species. However, current genetic association mapping analyses are focused on identifying individual QTLs. This study aimed to identify a set of QTLs or genetic markers, which can capture genetic variability for marker-assisted selection. Selecting a set with k loci that can maximize genetic variation out of high throughput genomic data is a challenging issue. In this study, we proposed an adaptive sequential replacement (ASR) method, which is considered a variant of the sequential replacement (SR) method. Through Monte Carlo simulation and comparing with four other selection methods: exhaustive, SR method, forward, and backward methods we found that the ASR method sustains consistent and repeatable results comparable to the exhaustive method with much reduced computational intensity.

基于多元储能的分布式能源系统优化调度方法研究

为进一步构建清洁低碳、经济节能的供能系统,研究建立了含风、光以及多元储能的分布式能源系统,针对北京某办公园区,采用DeST预测用户负荷以及当地风、光条件。以经济性、节能性和环保性三方面的综合效益最大为目标,提出一种自适应优化运行策略,分别采用穷举搜索法和遗传算法对系统优化调度方案进行优化。同时,采用以电定热运行策略作为对照,对比分析几种不同运行策略下系统的综合效益。结果表明:传统以电定热运行模式下的综合效益平均值为0.41;而在自适应优化运行策略下,使用遗传算法得到的调度方案,其综合效益平均值可达0.5,穷举搜索法得到的运行方案,其综合效益平均值可达0.51。

基于区段的地下空间环路通风排烟设计方法

为实现多匝道、多地块、内部空间复杂的地下空间环路烟气控制,提出一种区段式排烟方法:将地下空间环路与地块通过防火门分隔,形成独立的构筑物,结合隧道结构,确定风机房位置,划分区段,使烟气在一定区域内排出。以滨江地下环路为例,在隧道主线上均匀布置6个排烟风机房,并以此为节点,将隧道划分为8个区段。当火灾发生时,开启所在区段两端的风机进行排烟。由于各区段不设置固定分隔,整个风道是贯通的,因而各个风机房里的风机可互相作为备用排烟风机,以降低成本。采用数值模拟软件建立模型,对排烟口开启数量和间距进行模拟,确定排烟量为90 m^(3)/s、排烟口间距为30 m、开启8个排烟口的排烟方案。从人员疏散环境以及排烟效率对典型区段进行分析,结果表明:烟气控制在一定的范围内,人员疏散环境安全,排烟效率达到90%,证明方案合理可行。

辽宁省资源枯竭型城市转型发展时空动态变化分析

转型发展是资源枯竭型城市实现可持续发展的必由之路。为明晰辽宁省15个资源枯竭城市在辽宁老工业基地振兴关键期的转型发展时空动态演变特征,根据转型发展内涵,从经济发展、民生保障、环境污染治理三方面构建评价指标体系,运用熵值法计算2009—2019年的转型发展分值,ArcGIS 10.2进行空间分析。利用夜光遥感数据验证分析转型发展时空动态演变特征,并对两种方法的分析结果进行空间耦合。结果表明:(1)熵值法和夜光遥感分析结果的空间耦合性总体较好,空间耦合相一致区域占比为73.33%。(2)辽宁资源枯竭地区在10年间的转型发展动态变化率差异较大,葫芦岛市、盘锦市、北票市和葫芦岛南票区的转型发展提升率较高,抚顺市、调兵山市、义县和葫芦岛杨家杖子开发区的提升率较低。(3)资源枯竭城市转型发展中的共性问题是产业转型力度不够,第三产业占比较少;民生发展受下岗职工安置和再就业问题制约;生态环境恢复时间较长,短期内难见明显成效。(4)辽宁资源枯竭城市转型发展均以经济转型为主,民生转型次之,以生态环境转型为辅,多数地区存在发展短板,制约区域转型整体效果。

基于安全稀释法的柴油车CO综合海拔系数研究

为准确进行高海拔隧道施工通风设计,对高海拔隧道施工通风需风量计算方法及参数展开研究。对柴油车辆CO排放量进行多海拔测试,得到柴油车CO海拔系数;采用安全稀释法,推导出不同海拔下单位功率需风量及同时考虑CO排放量和控制标准变化的综合海拔系数。结果表明,柴油车CO浓度随海拔增高而增大,当海拔为3172 m时,柴油车释放的CO浓度约为平原地区(海拔590 m)的2倍;现有规范中柴油车CO海拔系数明显偏大,海拔3000 m处实测值较规范值减少25.61%;基于安全稀释法的施工通风需风量可根据海拔高度分3段计算,其结果较额定功率法计算需风量明显增大;根据现场测试结果,提出不同海拔区间(海拔2000 m以下、2000~3000 m和3000 m以上)柴油车CO综合海拔系数计算模型;安装DOC尾气净化器可以减少作业面处80%的CO排放量,在净化效率仅达到60%的情况下,基于安全稀释法计算的海拔5000 m处的计算需风量只有6.59 m^(3)/(kW·min)。

内河船舶碳排放监测技术探究

开展内河船舶碳排放监测可以为船舶碳减排政策的制定提供数据支撑,有助于国家“双碳”目标的推进。本文总结了国内外船舶碳排放监测技术的应用现状,包括排放因子监测法、台架试验法、现场人工监测法、在线监测法和远程监测法。分析了各监测技术的特点、优势及不足,探究了各监测技术在我国内河航运的适用性,最后提出了相关建议。

熵权-优劣解距离法综合评价油田加热炉能耗方法研究

为了提高油田加热炉运行效果,实现节能减排的目标,采用熵权法结合优劣解距离法对能耗水平进行评价分析。对K油田35台加热炉的空气系数、排烟温度、炉体表面温差、热效率4项指标进行分析,评价加热炉与理想工况的相对接近度,得出加热炉运行的整体情况,并对低效加热炉采取措施。研究表明,3台加热炉的相对接近度明显较低,主要原因是4项指标的综合作用导致,因此对35台加热炉进行综合调整,调整后的加热炉平均热效率由84.22%上升到87.32%,提高了3.68%,累计节约天然气44.97×10^(4)m^(3),折合经济效益157.4万元。

机动车尾气排放检测与维护(I/M)制度实施的问题与对策

机动车尾气排放是移动源污染的主要来源,严重影响城市空气质量和市民的身体健康。为打赢蓝天保卫战,严格执行机动车排放检测与维护(I/M)制度,强化机动车尾气排放检测,规范超标车辆闭环管理,是控制机动车污染物排放及改善城市环境质量的重要举措。基于此,本文主要探讨机动车排放检测的方法,并针对机动车排放检测与维护(I/M)制度存在的问题及改进对策进行探究,确保I/M制度顺利推进与实施。

机动车尾气检测方法与治理策略

伴随着中国城乡各界民众基本物质生活条件的持续改善,机动车购买数量和持有数量均呈现出持续增加变化趋势,其在为生产生活实践进程创造提供便利条件基础上,还引致出现较为严重的大气环境污染问题。为有效彻底解决大气环境污染问题,必须全面系统分析各类污染源,采取有效技术措施将机动车尾气排放水平控制在恰当范围内。要切实强化针对机动车尾气的检测工作力度与防治工作力度,切实将机动车尾气污染问题控制减少,助推社会主义生态文明建设历史进程。文章将会围绕机动车尾气检测方法与治理策略,展开简要的阐释分析。

某柴油机排温异常原因分析及解决措施研究

排气温度作为判断发动机是否正常的一个参数,作为柴油机故障判断依据之一,快速判断排气温度异常的原因并对其进行解决是保证发动机运行的基本要求。本文通过故障树分析法对某柴油机排温异常进行原因分析及解决,从燃油供给系统、冷却水系统、涡轮增压器以及外界环境因素入手,最终确认排温异常是由于试验环境导致进气量少使燃料燃烧不充分造成后燃引起,最终通过增加混气箱,增大柴油机进气量成功消除了排气温度过高的故障,并通过此次问题分析总结,为后续解决柴油机排温高的问题提供了完善系统的排除流程。

基于离子色谱法的废气中二氧化硫检测方法

目的:通过离子色谱法对废气中二氧化硫进行检测分析。方法:先进行当前废气中二氧化硫实时浓度值的计算,结合离子色谱法设置色谱柱及对应的检测参数,以此为基础,调整检测装置,设置间隔,通过对二氧化硫峰高波动比以及摩尔质量,测定出二氧化硫变异相关系数,进而最终得出相对检测偏差。结果:针对5个区域对应的5个废气检测反应管的验证,二氧化硫相对检测偏差分别是0.16、0.18、0.21、0.28、0.37。结论:二氧化硫相对检测偏差的高低与浓度及变动的幅度存在正向的关系,二氧化硫实时浓度值以及峰高波动比提升,检测偏差增加;二氧化硫实时浓度值以及峰高波动比降低,检测偏差减小。

集成排气歧管低周疲劳寿命研究

集成排气歧管的设计使排气部分收到高低温载荷的反复冲击,因此在局部区域会产生较大的应力集中,超过材料的屈服强度,产生塑性变形,会有低周疲劳破坏的风险。本文基于有限元的方法,计算某冲击循环的瞬态温度场结果,并基于此结果进行交变工况下的应力应变分析,研究排气部位危险位置的温度、应力和应变的变化规律,并基于局部应力应变法得到该位置的疲劳寿命,为缸盖设计提供一种分析方法。

轧钢企业工业炉安全环保智能化研究与应用

目前,工业炉的排烟系统多采用压差法或强制排烟法,排烟系统有故障时,只能停炉停风机维护,工时损失大;炉门信号检测装置不智能,运行可靠性差;保护性气氛随着烟气排到大气,热效率不高,以上因素均制约着产线智慧升级和安全环保生产。