滇中引水工程测量中椭球变换方法选定研究

系统地阐述与推导了椭球膨胀法、椭球变形法与椭球平移法3种常用的椭球变换方法,并在云南滇中引水这一典型的高原长距离工程测量中加以应用。针对3种方法进行了椭球参数变化分析、大地坐标变化分析、高斯投影坐标变化分析及长度变形分析,并比较了各种方法的差异性与一致性。分析结果表明,椭球膨胀法之广义微分法适宜作为滇中引水工程测量的椭球变换方法。     

新型旋流煤粉燃烧器出口区域气固两相流场的PDPA实验研究

针对电站锅炉燃用煤种多变和负荷多变的问题,提出了一种新型的旋流燃烧技术,即利用在一次风管中加装浓缩煤粉构件实行煤粉浓淡分离的旋流浓淡煤粉燃烧器。使用三维相位多普勒颗粒分析仪对旋流浓淡煤粉燃烧器和双调风旋流煤粉燃烧器出口区域气固两相流场进行了实验研究,得出了两种不同燃烧器几何结构下的气固两相流场和颗粒浓度场,并进行了理论分析。     

试析广州——一个正在形成的国际化城市

本文试图通过广州目前的国际化发展水平的分析,就如何迈向国际化城市提出几点看法.     

Agricultural water and energy management in Tajikistan: a new opportunity

ABSTRACT

Agricultural water use in Tajikistan is largely based on mechanized irrigation pumps. The farming community cannot afford the cost of the energy used for pumping, resulting in large debts to the service provider. We propose limiting pumping facilities for five years in exchange for energy export to neighbouring countries. The energy export could cover the annual pumping expenditures, pay off agricultural debt and partly rehabilitate the irrigation network. We suggest three scenarios with different pumping energy reductions, and the relevant technical parameters of the set-aside scheme are assessed.     

热水集中供暖系统调节监视控制装置的理论及应用

通过对供暖运行调节理论研究,开发出一套集中供暖运行调节系统,它改变了传统的靠人体感觉气温或天气预报对供暖方式进行温度控制及靠阀门开启大小调节流量的方式,而本系统能自动实时提供标准供暖温度及通过变频器准确控制循环流量。本文侧重对集中调节理论公式做了修正,并以修正公式为基础,介绍了集中调节控制供暖显示装置。     

华中电力系统抽水蓄能装机规模分析

华中电网在"全国联网、西电东送、南北互供"的战略中具有重要的枢纽作用.通过对华中电网调峰现状及华中电力系统抽水蓄能电站的建设规模、开发时机及站点布局等问题的分析,论证了华中电网2020年抽水蓄能电站的经济规模,并推荐了适当的抽水蓄能站点及适宜的开发时机.     

对中原白酒企业管理与质量管理的认识与思考

在介绍了中原白酒企业发展形势的基础上,通过分析豫酒的兴衰和轮回总结出了对中原白酒企业管理与质量管理的认识：应一手抓市场管理、一手抓质量管理,以质求存、理性引领企业发展;并通过加大原酒生产的投入和实施中原白酒的品牌战略来提高中原白酒的竞争力。     

Eutrophication of lakes in urbanized areas: The case of Yaounde Municipal Lake in Cameroon, Central Africa

A 1 year qualitative and quantitative evaluation of phytoplankton and chlorophyll‐a, as well as some physicochemical parameters, was recorded in a shallow tropical lake in Cameroon: the Yaounde Municipal Lake. Physicochemical measurements also were regularly made in its main tributary (Mingoa Stream). These analyses aimed to assess the lake's trophic status and to propose measures for controlling its degradation process. The Secchi disk transparency was low and rarely exceeded 100 cm. Conductivity was higher near the lake bottom. The oxygen deficiency, and sometimes anoxia, recorded from a 2.5 m depth leads to high quantities of ammonium‐nitrogen. The total phosphorus concentrations varied from 80–2290 µg P L^?1 and the total Kjeldhal nitrogen concentrations fluctuated between 3 and 15 mg  L^?1. Upstream to the lake, in the Mingoa Stream, total phosphorus concentrations ranged from 0.6–3.8 mg P L^?1 and total Kjeldhal nitrogen concentrations ranged from 10–22 mg  L^?1. There are up to 102 phytoplankton‐specific taxa, with Euglenophyta and Chlorophyta particularly more diversified. The phytoplankton biomass and chlorophyll‐a concentrations reached 225 µg mL^?1 and 566 mg m^?3, respectively. The analyses pointed out the allogenic nature of the functioning of this ecosystem as a result of bad waste management in the surrounding landscape. Urgent actions need to be undertaken in order to rehabilitate this lake, which rapidly shifted to a hypertrophic status.     

Optimisation of ultrasound-assisted extraction of phenolic compounds from wheat bran

Wheat bran, an important by-product of the cereal industry, is rich in potentially health-promoting phenolic compounds. In this paper, the phenolic compounds from wheat bran were extracted by ultrasound-assisted extraction technology. The experiments were carried out according to a five level, three variable central composite rotatable design (CCRD), and the best possible combination of solvent concentration, extraction temperature and extraction time with the application of ultrasound, for maximum extraction of phenolic compounds from wheat bran, was obtained, through response surface methodology (RSM). The optimum extraction conditions were as follows: ethanol concentration, 64%; extraction temperature, 60 °C; and extraction time, 25 min; and the extraction time was the most significant parameter for the process. Under the above-mentioned conditions, the experimental total phenolic content was 3.12 mg gallic acid equivalents/g of wheat bran tested, which is well matched with the predicted content.     

The past,present, and future Aral Sea

The Aral Sea, a once vast brackish terminal lake in the heart of Central Asia, has been rapidly drying since the 1960s. It had separated into four separate waterbodies by September 2009. The maximum water level decline was more than 26 m, whereas the lake surface area decreased 88% and the water volume 92%. The lake salinity increased by more than 20‐fold. Prior to the modern recession, the Aral Sea experienced a number of water level declines and subsequent recoveries over the last 10 millennia. The main causative factor until the 1960s was the periodic westward diversion of the Amu Dar’ya, the main influent river, towards the Caspian Sea by both natural and human forces. The post‐1960 recession, however, was overwhelmingly the result of unsustainable irrigation development. The lake’s modern recession has caused a broad range of severe negative ecological, economic and human welfare problems. To restore the Aral Sea to its 1960s’ size and ecological condition would be very difficult, if not impossible, in the foreseeable future. The plight of the Aral Sea, however, is far from hopeless. Partial restoration of portions of the lake is still feasible. A project to raise the Small (northern) Sea was completed in Fall 2005, raising its water level by 2 m, and lowering its salinity to a level not much higher than the early 1960 levels. Its ecological recovery has been dramatic, and a new project to improve further the Small Aral was recently announced. Improving the Large (southern) lake would be much more difficult and expensive. A project to save the deep Western Basin partially is technically feasible, however, and should be given careful evaluation. It is important to repair and preserve what is left of the deltas of the two tributary rivers, Syr Dar’ya and Amu Dar’ya, as these two rivers are of great ecological and economic value, and act as biological refugia for endemic species of the Aral Sea.