Preparation of Porous Nanofibers from Electrospun Polyacrylonitrile/Polyvinylidene Fluoride Composite Nanofibers by Inexpensive Salt Using for Dye Adsorption

The high surface area of porous nanofibers enhances their performance for many applications. The present study investigated electrospinning and dye adsorption properties of polymeric nanofibers which were porous by various types of salts. The salt/polyacrylonitrile/polyvinylidene fluoride composite nanofibers were electrospun, and the inexpensive salts such as sodium chloride (NaCl), sodium bicarbonate (NaHCO₃), or calcium chloride (CaCl₂) was used to manufacture the porous fibers. Subsequently, the salt was removed by a selective dissolution, and salt extraction of nanofibers was performed with the solution of hydrochloric acid (10 wt%). Salt/PVDF/PAN and porous PVDF/PAN composite nanofibers have been applied to dye adsorption of solution. The characteristics of nanofibers were studied by Fourier transform infrared microscopy (FTIR) and scanning electron microscopy (SEM) analysis. FTIR showed that the salt was extracted from PVDF/PAN nanofibers successfully, and SEM indicated that many pores were aligned with the nanofibers. The adsorption capacity of salt nanofibers webs and porous nanofibers webs for Basic Blue 41 were compared with each other, and porous fibers were obtained from NaHCO₃ having the highest dye adsorption value. Adsorption of dyes follows the Langmuir isotherm and pseudo-second order kinetics.     

Inexact fuzzy-stochastic constraint-softened programming – A case study for waste management

In this study, an inexact fuzzy-stochastic constraint-softened programming method is developed for municipal solid waste (MSW) management under uncertainty. The developed method can deal with multiple uncertainties presented in terms of fuzzy sets, interval values and random variables. Moreover, a number of violation levels for the system constraints are allowed. This is realized through introduction of violation variables to soften system constraints, such that the model’s decision space can be expanded under demanding conditions. This can help generate a range of decision alternatives under various conditions, allowing in-depth analyses of tradeoffs among economic objective, satisfaction degree, and constraint-violation risk. The developed method is applied to a case study of planning a MSW management system. The uncertain and dynamic information can be incorporated within a multi-layer scenario tree; revised decisions are permitted in each time period based on the realized values of uncertain events. Solutions associated with different satisfaction degree levels have been generated, corresponding to different constraint-violation risks. They are useful for supporting decisions of waste flow allocation and system-capacity expansion within a multistage context.     

Using fuzzy method to evaluate safety condition of big diesel engine

Big diesel engine is one of the most important equipments in industry, and its safety condition plays a great role in oil production. This paper presents a fuzzy method to monitor the safety state of the big diesel. Six useful diagnostic characteristic parameters have been selected to diagnose safety condition of the big diesel engine. The standard fuzzy vector was obtained by using statistical method, so the status of big diesel's safety condition can be determined by calculating the fuzzy distance between the fuzzy vector and standard fuzzy vector. This fuzzy method has been successfully used on PZ12V190 diesel engine.     

实时气体分析在控制炼钢过程中的应用

电弧炉二次燃烧和转炉煤气回收是炼钢过程中2个最重要的节能降耗手段.而这2个过程中都需要对气体浓度进行实时分析来反馈控制工艺过程.分析了这两个过程中的气体实时分析的重要性,并对正在开发的激光气体分析系统进行了简要介绍.     

农村居民点整理对农户土地投入影响研究

近年来,农村居民点整理被作为城乡统筹发展的重要措施,在各地广泛开展。其在改善农民居住环境、为工业化和城镇化发展置换建设用地空间的同时,也对区域农地资源可持续利用产生了巨大冲击,其中,土地投入变化是农户响应这些冲击的重要表现。本研究沿着"农村居民点整理-区域土地利用条件变化-农户土地利用行为响应"的逻辑思路,形成了农村居民点整理对农户土地投入影响的分析框架,并在此基础上,从总体效应和不同政策影响两个层次,构建了农村居民点整理对农户土地投入影响的两个模型。依据江苏省调研数据,从资金和劳动力两个方面,实证分析农村居民点整理项目对农户土地投入的净效应,以及不同居民点整理政策对农户土地投入的影响方向和大小。结果表明,农村居民点整理促进了农户的土地资金投入,但对农户的土地劳动力投入具有负向影响。不同居民点整理政策对农户土地投入的影响具有显著差异,其中,置换住房的宅基地补偿政策和农地产权稳定政策对农户的土地资金投入具有较好的积极作用,而安置公寓房政策则更可能带来农户土地资金投入减少;农地产权稳定政策和安置公寓房政策显著负向影响农户土地劳动投入,但宅基地补偿政策对农户土地劳动投入影响不显著。本研究对这些结果进行了合理解释,同时也估算了户主年龄、户主受教育程度、农业收入比例、非农就业水平、农业补贴收入、耕作距离和土地经营面积等控制变量对农户土地投入的影响情况。最后从强化规划引导、内涵拓展、宅基地补偿策略优化、土地流转制度完善等方面,提出农村居民点整理政策调整和合理引导农户土地投入行为的对策建议。     

资源环境与我国可持续发展

本文从资源、环境和人地关系的角度探讨我国的可持续发展问题 ,分析了影响我国可持续发展因素 ,指出中华民族的人口素质是我国可持续发展的关键 ,阐明科教兴国是我国可持续发展的必由之路     

Carbon Emission by Soils in Forests Damaged by the Siberian Moth

In the southern-taiga low grass–green moss fir forest completely defoliated by the Siberian moth, the rate of soil respiration in the third year after the pest population outbreak was 1.5 times higher than in an undisturbed tree stand. This was explained by a significant increase in the abundance and activity of soil microorganisms in the pest-defoliated forest, which occurred due to the qualitative changes in the litter composition and the increased temperature and moisture in the upper soil layers. The rate of carbon emission from the soil in the defoliated forest was 41.7 kg/ha per day, compared to 28.3 kg/ha per day in the undisturbed fir forest.     

气候变化对江汉平原调水格局的影响

江汉平原水利工程密布,大型调水工程对流域用水格局产生很大影响。气候变化同时会影响调水工程调入调出区供需水情况,从而影响流域的水资源的分配。梳理了江汉平原主要调水工程,重点围绕南水北调中线工程与引江济汉工程的规划设计指标及实际运营状况,分析江汉平原潜在的用水矛盾。此外,在未来气候变化情景下,随着干旱时长和频次增加,会导致各调水工程抽水引水成本提高,从而加剧江汉平原用水矛盾。结果表明:(1)从工程设计和运行来看,南水北调中线工程达到调水设计后,引江济汉工程在保证汉江下游用水需求上受限可能性很大;(2)引江济汉工程自运行以来,虽未有较长时间的泵站抽水引水,但就2018年的泵站抽水引水成本来看已经达到运行总经费的30%。如果引江济汉工程引水口长江水位下降,自流引水受限,使用泵站抽水引水时长及频率将会增加,会导致引水费用进一步增加;(3)"南水北调中线"、"引汉济渭"、"鄂北水资源配置"工程,再叠加汉江中下游生产生活用水,如遇枯水年份,汉江水资源配置会产生很大的矛盾,对汉江流域及汉江生态经济带发展将产生影响。     

大城市的城市化发展战略和途径研究--以南京市为例

城市化从本质上是一种经济社会结构变动过程，南京市作为长江三角洲的副中心城市和江苏省省会，需要认真研究在经济全球化背景下，如何加快推进城市化进程，发挥中心城市功能，促进城市现代化和可持续发展。城市化水平的提高、大城市中心功能的加强、较为明显的城乡二元结构是南京市城市化过程中的基本特征。南京城市化的发展遇到了前所未有的机遇，江苏省已经提出了大力规划建设以南京市为中心的都市圈，并在2001、2002连续2年扩张南京市区的范围，大大加强了南京市的综合实力。南京的城市化发展主要途径在于提升城市功能，奠定城市化的经济基础；以城市空间优化为支点，以基础设施建设为引导，提高城市现代化水平；增强中心城市辐射功能．带动城乡一体的发展。推进南京城市化的进程还必须要制定一些政策和措施傲保证，如加快户籍制度和土地制度的改革、加大投资融资的力度、制定各类切实可行的规划等等。