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11.
通过直升机实际使用过程中暴露的腐蚀问题,分析了直升机全寿命期的腐蚀防护应对方法和思路。对陆地环境和海洋环境使用直升机的腐蚀情况进行了汇总,并对直升机典型腐蚀问题及改进措施进行了研究。在此基础上,进一步分析了导致直升机发生腐蚀的环境、设计、生产、制造、维护等原因,总结了直升机易腐蚀部位、腐蚀特点以及危害性。提出了采用“设计保证、生产实现、维护保持”的综合手段来提升直升机全寿命期的腐蚀防护能力。最后,对外场维护维修过程中需要重点关注的腐蚀控制手册、清洗、涂镀层修复、密封剂/缓蚀剂等问题进行了思考和分析,提出了需加快推进先进的防腐技术在直升机防腐中的应用,对有效开展直升机全寿命周期的腐蚀防护工作具有一定指导意义。 相似文献
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目的 将电子产品在野外环境下日变化波动与季节差异明显的温度载荷编制成温循载荷谱和转换为加速载荷谱。方法 通过四点雨流计数法提取原谱中的载荷循环信息,对提取的循环信息进行分布拟合、相关性检验等统计分析,进而构建循环均值与范围值的联合概率密度函数,再运用概率密度法,编制出8×8二维环境载荷谱。在二维载荷谱基础上,编制出温循载荷谱,使用针对电子部件参数修正的加速方程转化为加速载荷谱。结果 利用野外作业现场1个作业周期内的气温纪录,提供了一套编制温循载荷谱和转换加速载荷谱的合理化流程和解决方案。结论 该制谱方法可以利用原始环境谱中绝大部分有效信息,较好地还原电子部件野外作业阶段经历的温度变化过程,为电子产品的加速寿命试验和使用寿命预测奠定基础。 相似文献
13.
Bohan Liao Zhaohui Guo Qingru Zeng Anne Probst Jean-Luc Probst 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):151-161
Leaching experiments of rebuilt soil columns with two simulated acid rain solutions (pH 4.6–3.8) were conducted for two natural
soils and two artificial contaminated soils from Hunan, south-central China, to study effects of acid rain on competitive
releases of soil Cd, Cu, and Zn. Distilled water was used in comparison. The results showed that the total releases were Zn>Cu>Cd
for the natural soils and Cd>Zn≫Cu for the contaminated soils, which reflected sensitivity of these metals to acid rain. Leached
with different acid rain, about 26–76% of external Cd and 11–68% external Zn were released, but more than 99% of external
Cu was adsorbed by the soils, and therefore Cu had a different sorption and desorption pattern from Cd and Zn. Metal releases
were obviously correlated with releases of TOC in the leachates, which could be described as an exponential equation. Compared
with the natural soils, acid rain not only led to changes in total metal contents, but also in metal fraction distributions
in the contaminated soils. More acidified soils had a lower sorption capacity to metals, mostly related to soil properties
such as pH, organic matter, soil particles, adsorbed SO4
2−, exchangeable Al3+ and H+, and contents of Fe2O3 and Al2O3. 相似文献
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Natural scientists are increasingly interested in social research because they recognize that conservation problems are commonly social problems. Interpreting social research, however, requires at least a basic understanding of the philosophical principles and theoretical assumptions of the discipline, which are embedded in the design of social research. Natural scientists who engage in social science but are unfamiliar with these principles and assumptions can misinterpret their results. We developed a guide to assist natural scientists in understanding the philosophical basis of social science to support the meaningful interpretation of social research outcomes. The 3 fundamental elements of research are ontology, what exists in the human world that researchers can acquire knowledge about; epistemology, how knowledge is created; and philosophical perspective, the philosophical orientation of the researcher that guides her or his action. Many elements of the guide also apply to the natural sciences. Natural scientists can use the guide to assist them in interpreting social science research to determine how the ontological position of the researcher can influence the nature of the research; how the epistemological position can be used to support the legitimacy of different types of knowledge; and how philosophical perspective can shape the researcher's choice of methods and affect interpretation, communication, and application of results. The use of this guide can also support and promote the effective integration of the natural and social sciences to generate more insightful and relevant conservation research outcomes. Una Guía para Entender la Investigación de Ciencias Sociales para las Ciencias Naturales Katie Moon 相似文献
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为解决传统冻结壁设计方法不能真实、合理地反映黏土地层中联络通道冻结壁实际受力情况,进而导致冻结壁厚度设计过于保守的问题,结合黏土地层直墙拱形冻结壁实际受力特点,基于对冻结壁支护压力的合理计算,提出1种适用于黏土地层冻结壁厚度设计的优化方法。结果表明:与传统设计方法相比,该方法所确定冻结壁支护压力与实际施工环境中冻结壁受力状态吻合效果更好,并且能够提供合理的安全储备;经数值计算和现场应用验证,计算所得冻结壁设计方案可以满足施工环境中的承载力及变形稳定性要求;且相较传统设计方案,所得方案兼具安全性与经济性,可有效规避因设计过于保守和冻结周期过长引起的冻胀、融沉变形过大等工程灾害的风险;该方法高效、易行,可为传统冻结壁设计方法提供必要补充,亦可为类似工程的施工设计提供有益参考。 相似文献
19.
Rainfall interception represents the amount of water trapped in natural cover that is not drained directly to the ground. Intercepted rainfall may evaporate after a rain event, making it one of the main drivers of water balance and hydrologic regionalization. This process can be affected by factors such as climate, altitude, vegetation type, and topography. Here is a simple method of calculating rainfall interception in temperate forests using in Santa Maria Yavesia, Oaxaca, and Mexico as an illustrative study area. We used two rain gauges to measure net precipitation (Np) under the canopy at each study site and one gauge outside the canopy to obtain gross precipitation (Gp). Throughfall (Th) was indirectly measured using hemispherical photographs. Rainfall interception was obtained through a combination Th and Gp and Np. The mean rainfall interception was 50.6% in the Abies forests, 23%–40% in the coniferous‐mixed forests, and 27.4% in the broad‐leaved forests. We classified rainfall events by intensity to determine the effect of canopy structure and precipitation and found that 75% of the events were weak events, 24% were moderate events, and 1% were strong events. In addition, we found that rainfall interception was lower when the intensity of precipitation was higher. Our method can be replicated in different ecosystems worldwide as a tool for assessing the influence of rainfall interception in terms of ecological services. 相似文献
20.
The accomplishments of inherent safety in the field of loss prevention thus far are impressive due to its scientific philosophy: reducing risks at source rather than adding engineered and procedural protections. Generally, the implementation of inherent safety can be done through a cohesive set of fourteen principles elucidated by Kletz and Amyotte. This work, guided by the fourteen principles, presents a systematic review on the implementation methodologies of inherent safety. Firstly, PRISMA procedure was adopted to select eligible literatures according to inclusive and exclusive criteria. After obtaining the selected literatures, the preference, level of application, and gaps in using these principles were critically analyzed. Of the fourteen principles, intensification, substitution, attenuation, simplification, limitation of effects, and avoidance of knock-on effects are preferable to implementing inherent safety in chemical process. Although the remaining principles are also potentially useful, they are not commonly used due to their costs and complexities of implementation. Overall, this work presents a complete spectrum to look across the implementation methodologies of inherent safety and concludes with some holistic and inclusive approaches as future research recommendations. 相似文献