污水源热泵渠温受地温作用下的温变模型

为更广泛地应用原生污水源热泵技术,有必要对干渠污水与土壤的耦合特性进行深入研究和分析.调查并分析干渠散热时的物理模型与边界条件,基于虚拟热源镜像法,引入并假定土壤地温及其简化条件.理论解析干渠周边土壤温度场及干渠沿程温度函数,为适于工程应用,对渠程温变模型作近似处理与示例.研究表明:干渠散热时的物理模型与边界条件复杂,难以得到精确解.可理论解析近似得到干渠与土壤传热耦合模型,温度场是以同等埋深的土壤地温为渐近线的曲面,而渠温则终将趋于埋深处的地温,由两个特征常数决定.简化的模型适宜工程应用,符合物理机理.     

末级渠系节水配套工程建设及管理探讨

根据目前淠史杭灌区末级渠系的管理状况,末级渠系节水配套工程建设、建后管理中的问题,提出改进措施。     

临清市历史文化资源产业化开发探究

作为运河城市的临清市,历史文化底蕴深厚,文化资源丰富,具有鲜明的运河文化地缘特征,优越的开发条件.依据历史文化资源可持续发展原则,结合临清市历史文化资源发展特点,对临清市历史文化资源开发利用的基本情况、开发条件及存在的问题进行分析,提出了实现运河城市历史文化资源产业化运作的构想.     

宁夏平罗县井渠结合灌区地下水盐运移规律研究

以综合治理井渠结合灌区土壤盐碱化为目标,针对宁夏平罗县井渠结合灌区下游灌水难、排水难和盐碱化严重等问题,采用渠灌井排、井沟联合使用等措施,对作物进行适量和适时灌溉,充分利用地下水资源,并监测井渠结合灌溉条件下田间土壤含盐量、地下水矿化度和水位埋深的变化情况,分析地下水埋深和矿化度对土壤含盐量的影响。结果表明:井渠结合灌溉对降低地下水位效果显著。以黄河水为主要灌溉水源的宁夏银北自流灌区,地下水矿化度变化幅度较小;灌溉后的土壤表层含盐量骤降,0~40 cm土层的盐分变化较大;土壤盐分与地下水矿化度具有较强的线性正相关性,与地下水埋深呈负相关。研究成果对干旱半干旱区灌区水资源优化配置、盐碱地改良具有参考价值。     

新疆灌溉渠系水资源优化配置技术分析

研究了渠系优化配水模型一般形式和求解方法,及优化配水模型的应用、管理中存在的问题;论述了灌溉水量配置不合理现象;分析了灌溉水的利用率及其利用效率低下的原因,对进一步研究建立干旱灌区渠系水量优化调配模型具有借鉴意义.     

新疆灌溉渠系水资源优化配置技术分析

本文介绍了灌溉渠系优化配水模型在国内外的研究进展,渠系优化配水模型的一般形式及其求解的一般方法,以及建立的优化配水模型的应用和在管理中存在的问题,论述了灌溉水量配置不合理现象,分析了造成灌溉水的利用率和利用效率低下的原因,对进一步研究建立干旱灌区渠系水量优化调配模型具有借鉴意义。     

Percentage of gutta-percha in mesial canals of mandibular molars obturated by lateral compaction or single cone techniques

The aim of this study was to compare the percentage of gutta‐percha (PGP) in mesial root canals of mandibular molars obturated with LC (Lateral Compaction) or SC (Single Cone) ProTaper Universal System techniques at different levels of the root. Mesial root canals of 20 human permanent molars with similar anatomical characteristics were instrumented using the ProTaper Universal rotary system technique until the F2 instrument, with 20 canals filled by SC ProTaper Universal technique and 20 canals by the LC technique. The mesial roots were sectioned transversely to 3, 5, and 7 mm from the root apex. Digital images of specimens were obtained at MIC‐D digital microscope in increases of 30 to 35X. The gutta‐percha area was measured using ImageTool software. Data were analyzed using two‐way ANOVA and Bonferroni test (α = 0.05). The SC technique provided greater PGP than the LC technique in the apical third (3 mm) (P < 0.001). In the other thirds (5 and 7 mm) there was no statistical difference between the two techniques regarding the PGP (P > 0.05). There was no statistically significant difference between thirds of the root canal for both techniques (P > 0.05). It was concluded that SC technique provided greater PGP than the LC technique in the apical third of mesial root canals of mandibular molars. There was no difference between the two techniques regarding the PGP in the cervical and middle thirds. Microsc. Res. Tech. 75:1229–1232, 2012. © 2012 Wiley Periodicals, Inc.     

SEM evaluation of thermoplastic endodontic materials alterations after disinfection: a new experimental model

This study assessed a new experimental model to analyze the effects of sodium hypochlorite solution 2.5% for 10 min and chlorhexidine 2% for 15 s on cones surface alterations. Twenty five gutta-percha and 25 thermoplastic synthetic polymer-based cones had their last 1 mm from the tapered end examined by scanning electron microscopy (SEM) before and after being exposed to the disinfectant solutions. To allow the surfaces to be compared, the samples were not metalized, a voltage of 1 kV was used and the images were captured within standardized angles. The samples were immersed on the test solutions. The comparison of the alterations of the cones was performed using the software program Adobe Photoshop CS. A measurement was taken of the standard deviations of the pixel intensity in this area, higher standard deviations represent more irregular areas. Differences in standard deviation before and after disinfection for each cone were compared between groups by means of analysis of variance supplemented by the Tukey test. Gutta-percha cones showed higher standard deviations than Resilon cones (P < 0.001). In the gutta-percha cones, sodium hypochlorite generated more irregular areas than chlorhexidine and the control group (P < 0.001). The present study has demonstrated the feasibility of using a modified SEM method. This opens opportunities to the use of new and precise tools for evaluating a sample in different moments.     

古运河环境景观设计及理论纲要--以无锡市环城四公园景观规划为例

以无锡市环城四公园景观规划为例,来探讨古运河环境景观设计及理论纲要,认为古运河环境景观设计宗旨为水脉、绿脉、文脉,三脉合一.其中水脉、绿脉是古运河的生态主体、景观空间载体,文脉则是体现古运河的精髓、底蕴、景观时间载体,两者融为一体才能再创古运河的辉煌.     

FORTRAN语言在渠道断面设计中的应用

水利灌溉工程中渠道的设计是经常遇到的。传统的渠道设计是用“试算法”、“图解法”。利用这两种方法比较繁琐,特别是在需要计算的渠道断面很多的情况下,同样的计算步骤要重复很多次。应用FORTRAN语言编写的“渠道断面计算程序”,可以代替人工的计算工作,提高工作效率。