Effects of urban green belts on the air temperature, humidity and air quality

As urbanization increases, designing green space that offers ecological benefits is an increasingly important goal of urban planning. As a linear green space in an urban environment, green belts lower air temperature, increase relative humidity, and improve air quality. To quantify the ecological effects of urban green belts and to identify a critical width for effective urban green belts, we analysed the width of urban green belts in terms of their effects on air temperature (T), relative humidity (RH), concentration of negative air ions (NAI) and bacteria rate (BR). The air T, RH and NAI from 8:00 to 18:00 and BR at 9:00 over seven days were investigated on six widths of green belts (0–10 m, 10–20 m, 20–30 m, 30–40 m, 40–50 m and over 50 m) along the west Fourth Ring Road of Beijing in April, July, October and December 2009. We found that (1) the T-RH benefits increased with the width of the green belts, and the 6 m belt had the smallest effect on T-RH, followed by the 16 m and 27 m belts, whereas the effect was obvious with the 34 m belt and conspicuous and stable with the 42 m belt (approximately 80% green coverage) (P < 0.05); (2) the critical width reference value of urban green belts for an obvious effect on the increase in NAI concentration was approximately 42 m (approximately 80% green coverage) (P < 0.05) and the NAI concentration increased with the width of green belts even in July; and (3) the positive effect on the decrease in the BR was greater than the negative effect, the BR decreased with the green belt width and the changes in the brs were stable with the 34 m belt. The results of this study may help urban planners and designers achieve urban green space designs that optimize ecological effects and cultural benefits

Optimization Design of IGV Profile in Centrifugal Compressor

Variable inlet guide vane (IGV) is used to control the mass flow and generate prewhirl in centrifugal compressors. The efficient operation of IGV is limited to the range of aerodynamic characteristics of their vane profiles. In order to find out the best vane profile for IGV regulation, the modern optimization method was adopted to optimize the inlet guide vane profile. The main methodology idea was to use artificial neural network for continuous fitness evaluation and use genetic algorithm for global optimization. After optimization, the regulating performance of IGV has improved significantly, the prewhirl ability has been enhanced greatly, and the pressure loss has been reduced. The mass flow and power of compressor reduced by using the optimized guide vane at large setting angles, and the efficiency increased significantly; the flow field distribution has been improved obviously, since the nonuniform distribution of flow and flow separation phenomenon greatly weakened or even completely disappeared. The achievement of this research can effectively improve the regulation ability of IGV and the performance of compressor

Experimental Investigation of Permeability Evolution on Sandstone in Triaxial and Long-Term Dissolution Experiment

The temporal permeability and damage evolutions of low-permeability sandstone cores during triaxial and long-term dissolution experiments were measured using a triaxial-flow system. Three triaxial experiments were performed on sandstone cores having initial permeability ranging from 78×10−18 m2 to 120×10−18 m2. Two sets of long-term dissolution experiments were conducted on cracked sandstone cores. All dissolution experiments were performed at room temperature and using a 10 g/L H2SO4 and 0.2 g/L H2O2 input solution. Permeability evolution was determined using Darcy’s law. The cores experienced an average increase of 25% in permeability in the dissolution experiment and 900%~1500% increase at the end of the experiment. The dissolution was fairly homogeneous during the long-term experiments whether on the 1 mm scale or the 10 μm scale. The relationship between damage and permeability was speculated and its correlation coefficient has been proved to be close to 1. These results suggest that hydraulic fracturing works well in permeability increase in low-permeability sandstone reservoir

constructing a data accessing layer for in-memory data grid

In-memory data grid (IMDG) is a novel data processing middleware for Internetware. It provides higher scalability and performance compared with traditional rational database. However, because the data stored in IMDG must follow the key/value data model, new challenges have been proposed. One important aspect is that IMDG does not support standard data accessing languages such as JPA and SQL, and application developers must design their programs according to the peculiarities of an IMDG product. This results in complex and error-prone code, especially for the programmers who have no deep understanding of IMDG. In this paper, we propose a data accessing reference architecture for IMDG and a methodology to design and implement its data accessing layer. In this methodology, data accessing engine construction, data model designation and join operation supporting are presented. Moreover, following this methodology, we develop and implement a JPA compatible data accessing engine for Hazelcast as a case study, which proves the feasibility of our approach. Copyright 2012 ACM.CCF-TSE; CCF-TSSIn-memory data grid (IMDG) is a novel data processing middleware for Internetware. It provides higher scalability and performance compared with traditional rational database. However, because the data stored in IMDG must follow the key/value data model, new challenges have been proposed. One important aspect is that IMDG does not support standard data accessing languages such as JPA and SQL, and application developers must design their programs according to the peculiarities of an IMDG product. This results in complex and error-prone code, especially for the programmers who have no deep understanding of IMDG. In this paper, we propose a data accessing reference architecture for IMDG and a methodology to design and implement its data accessing layer. In this methodology, data accessing engine construction, data model designation and join operation supporting are presented. Moreover, following this methodology, we develop and implement a JPA compatible data accessing engine for Hazelcast as a case study, which proves the feasibility of our approach. Copyright 2012 ACM