Design of unsurfaced roads constructed with large-size shredded rubber tires: a case study

Stockpiles of scrap tires are serious fire hazard, public health hazard, and an environmental burden. The construction of road embankments, using tire shreds as a lightweight fill, can consume large quantities of scrap tires and has certain engineering benefits. All the previous research focused on small size tire shreds (3–6 in. size) in terms of its use in civil engineering applications and determination of the engineering/environmental properties. This research specifically focuses on large size tire shreds (12 in. size) and its direct comparison with the other sizes of the tire shreds to develop mechanistic-empirical practical design model and so that the use of tire shreds in road bases could be used on regular basis with enhanced reliability instead of on an empirical basis. The research also examines the potential environmental implications of the use of shredded rubber tires and the comparison of the short-term results with other long-term monitoring studies.     

关于房间空气调节器不稳定状态的热泵制热量试验中一些问题的探讨

不稳定状态的热泵制热量试验是房间空调器.试验中新增加的项目,本文对在实际试验操作时遇到的几个问题进行了探讨并结合实际经验提出了一些建议.     

Stress responses of Calluna vulgaris to reduced and oxidised N applied under 'real world conditions'

Effects and implications of reduced and oxidised N, applied under 'real world' conditions, since May 2002, are reported for Calluna growing on an ombrotrophic bog. Ammonia has been released from a 10 m line source generating monthly concentrations of 180-6 microg m(-3), while ammonium chloride and sodium nitrate are applied in rainwater at nitrate and ammonium concentrations below 4mM and providing up to 56 kg N ha(-1) year(-1) above a background deposition of 10 kg N ha(-1) year(-1). Ammonia concentrations, >8 microg m(-3) have significantly enhanced foliar N concentrations, increased sensitivity to drought, frost and winter desiccation, spring frost damage and increased the incidence of pathogen outbreaks. The mature Calluna bushes nearest the NH3 source have turned bleached and moribund. By comparison the Calluna receiving reduced and oxidised N in rain has shown no significant visible or stress related effects with no significant increase in N status.     

山东省近600年旱涝霜雹数据库和超长期预报系统研究

干旱、洪涝、霜冻、冰雹是山东省最主要的气象灾害,具有频率高、范围广、灾情重等特征。通过对历史资料的整理、编码和输入,建立了山东省近600年旱涝霜雹数据库、近40年降水数据库和预报因子数据库,并编制了数据管理和分析软件包,在国际著名的SAS统计分析系统基础上,建立了山东省旱涝霜雹超长期预报系统。本文简要论述灾害数据库和预报系统建立的技术方法及系统应用的初步结果。     

Impacts of changing frost regimes on Swedish forests: Incorporating cold hardiness in a regional ecosystem model

Understanding the effects of climate change on boreal forests which hold about 7% of the global terrestrial biomass carbon is a major issue. An important mechanism in boreal tree species is acclimatization to seasonal variations in temperature (cold hardiness) to withstand low temperatures during winter. Temperature drops below the hardiness level may cause frost damage. Increased climate variability under global and regional warming might lead to more severe frost damage events, with consequences for tree individuals, populations and ecosystems. We assessed the potential future impacts of changing frost regimes on Norway spruce (Picea abies L. Karst.) in Sweden. A cold hardiness and frost damage model were incorporated within a dynamic ecosystem model, LPJ-GUESS. The frost tolerance of Norway spruce was calculated based on daily mean temperature fluctuations, corresponding to time and temperature dependent chemical reactions and cellular adjustments. The severity of frost damage was calculated as a growth-reducing factor when the minimum temperature was below the frost tolerance. The hardiness model was linked to the ecosystem model by reducing needle biomass and thereby growth according to the calculated severity of frost damage. A sensitivity analysis of the hardiness model revealed that the severity of frost events was significantly altered by variations in the hardening rate and dehardening rate during current climate conditions. The modelled occurrence and intensity of frost events was related to observed crown defoliation, indicating that 6-12% of the needle loss could be attributed to frost damage. When driving the combined ecosystem-hardiness model with future climate from a regional climate model (RCM), the results suggest a decreasing number and strength of extreme frost events particularly in northern Sweden and strongly increasing productivity for Norway spruce by the end of the 21st century as a result of longer growing seasons and increasing atmospheric CO₂ concentrations. However, according to the model, frost damage might decrease the potential productivity by as much as 25% early in the century.     

Reproduction of olive tree habitat suitability for global change impact assessment

The olive tree is so typical of the Mediterranean climate that its presence in a territory qualifies the climate of this as Mediterranean. Many clues indicated that in the past olive cultivation limits moved northward or southward in the Northern Hemisphere according to warmer or cooler climate, respectively. This makes the olive tree cultivation area a possible biological indicator of changes in climate and the identification of the climatological parameters that limit its cultivation plays an important role for climate change impact assessment. In this work, three different approaches were compared, with the aim to compare methodologies suited to predict olive tree distribution over the Mediterranean basin: two classifiers (Random Forest, RF and an Artificial Neural Network, ANN) and a spatial model to infer climatic limiters of plant distribution (CLPD). These methodologies were applied within a framework including a geographical information system (GIS), which spatially defined olive tree cultivated area, and climatological informative layers (average temperature and cumulated rainfall, 50 km × 50 km), which were used as predictor variables. The results indicated that RF achieved on the whole, the lowest classification error (113 misclassified cases on 1906 test cases) followed by ANN (128 cases) and CLPD (153 cases). A validation test, performed over areas out of the Mediterranean basin where olive tree is cultivated (i.e. California and Southern Australia), confirmed the goodness of the RF fitted model in predicting olive tree suitable areas. In general, climatic predictor variables of the coldest and warmest periods of the year were the most significant in determining the limits of suitable olive cultivation area for these methodologies. In particular, temperature of January and July and rainfall of October and July were the climatic predictor variables having highest significance for both RF and ANN. Temperature of January >2 °C, of July >20 °C and cumulated annual rainfall >240 mm were the bounds found in the spatial model. The fitted RF model, coupled with the results of both Regional and General Circulation Model, was finally proposed to assess climate change impact on olive tree cultivated area in the Mediterranean basin.