基于遥感信息的黄河中游水土流失敏感区淤地坝坝地资源特征研究

淤地坝是黄河中游黄土高原区水土流失防治的有效工程措施之一,在拦泥淤地、建设农田、巩固退耕还林（草）、改善生态环境等方面发挥了重要作用。基于WorldView-2、Google Earth、Bing、Sentinel-2多源遥感影像并结合实地淤地坝监测资料、NDVI和土地类型数据,本文完成了晋西南地区淤地坝坝地资源（数目、面积、位置、坝系、流域面积）的统计,并对其运行现状进行了评估。结果表明：截至2021年,晋西南地区淤地坝共计12167座,总面积达71.19 km²。规模上该区主要以小型淤地坝（＜0.015 km²）为主;空间上主要集中于中部的汾西县、洪洞县和浮山县地区,坝地数量和面积分别占总数量和面积的67.37%（8197座）和56.67%（40.35 km²）。目前,56.58%的淤地坝已经处于服务超限状态,平均超限5—10 a,其中,隰县、大宁县、汾西县、吉县和乡宁县地区淤地坝超限较为严重,60%以上的淤地坝已处于淤满状态。淤地坝的修建明显促进了黄土高原地区植被恢复、拦泥蓄容、建设耕地资源,但随着一些淤地坝的“淤满”,其生态和经济服务功能明显下降,并存在一定的潜在风险,亟需地方流域管理部门重视并采取有效措施。     

Deteriorated watersheds can be restored: A case study

A project in west-central Colorado demonstrated that a watershed dissected by a dense gully network can be stabilized and rehabilitated. Check dam systems, aided by improved vegetative cover through reduced cattle grazing and plantings, stabilized not only the structurally treated gullies, but also gullies within the network that were not structurally treated. Comparison with untreated gullies located outside of the project area, showed that the outside gullies widened three times as much as the structurally untreated inside gullies. Statistical analysis indicated that precipitation was normal during the treatment and evaluation period.Check dams decreased gully depth by accumulating sediment deposits. In turn, gully bank stabilization was hastened and alluvial aquifer volumes increased. This increase, plus higher infiltration rates as a result of denser vegetation, led to renewed perennial streamflow after 7 treatment years.Within 11 years after treatment, check dam systems and improved vegetation reduced sediment loads in the flows by more than 90 percent, providing a substantial benefit to farmlands and ponds downstream.From this work we are able to conclude that only part of a gully network requires structural treatment. The mainstem gully, and those tributaries controlling the local base levels of others, are the critical segments that should be structurally treated.     

关于建立我国工业企业系统安全分析的理论与方法体系的研究

基于当前世界各国安全科学研究的新成果、新经验，结合我国近年来各类事故频繁，损失惊人的情况，运用系统科学的思想，提出了“系统安全价值”思想和“大安全”观点。进而探讨了系统失效的识别、预测与控制理论和方法，系统安全投入的优化分析与安全价值分析体系，并通过这一体系，建立或改进我国工业企业系统安全管理模式，提高管理水平，实现系统安全化。     

TWO-DIMENSIONAL DIFFUSION-PROBABILISTIC MODEL OF A SLOW DAM BREAK1

ABSTRACT: A two-dimensional model of a dam-break flood wave is developed by simplifying the St. Venant equations to eliminate local acceleration and inertial terms and combining the simplified equations with continuity to form a diffusion type partial differential equation. This model is cascaded with a two point probability estimate scheme to account for uncertainty in the dam break flood hydrograph and channel roughness. The development and application of the probabilistic model is the main contribution of this paper. The approach is applied to a hypothetical dam break of Long Valley Dam on the Owens River above Bishop, California.     

摆动辗压模具的材料选择

分析了摆辗模具的工作原理、失效形式 ,合理地选择材料及制定热处理工艺 ,可以大大提高模具寿命     

噪声与静压载荷同时作用下飞机壁板试验研究

目的 模拟飞机结构承受静压载荷与噪声载荷时的真实情况,为飞机设计初期阶段设计选型提供试验数据支持。方法 使用压缩空气进行静压加载,模拟噪声与正压、噪声与负压联合加载,并以静压载荷0.06 MPa、噪声载荷151 dB为例,进行了试验验证。结果 在噪声与静压载荷同时作用下,若静压载荷过大,结构会发生塑性变形。结论 提出的飞机选型阶段噪声与静压载荷联合加载的试验方法,实现了噪声与静压(正压与负压)联合加载,并通过飞机壁板声静联合试验,验证了飞机壁板结构的噪声与静压联合试验方法。     

某型飞机液压泵安装座螺栓断裂失效分析

目的探究某型飞机液压泵安装座固定螺栓断裂原因。方法通过观察多组螺栓的断口形貌,以及对其进行力学性能测试和材料组织分析。结果螺栓断口边缘无明显的腐蚀氧化特征,有较为明显的氢脆断裂断面特征,螺栓的硬度均超过标准,并未发现有害的夹杂物和磷化物。结论螺栓在制造时可能存在缺陷,硬度超标和除氢不完全是造成断裂的主要原因。并根据分析结果对生产商提出相关建议和检查方向。     

差速器螺栓失效行为研究

目的研究车辆差速器螺栓失效原因。方法在化学成分、非金属夹杂物、力学性能、金相组织、断口形貌等检测分析的基础上,研究车辆差速器螺栓的失效行为,推断失效原因。结果差速器螺栓化学成分、氢含量、心部硬度及金相组织、材料抗拉强度及屈服强度等均未见明显异常,断口有明显的疲劳断裂特征,螺纹表层存在脱碳现象,脱碳层深度约为0.07 mm。裂纹起始于螺纹根部,裂纹两侧无脱碳现象,螺纹表面及裂纹内部均未见腐蚀产物。结论由于表面脱碳使得差速器螺栓表面硬度及疲劳强度降低,而螺纹根部存在的应力集中使早期裂纹在螺纹根部产生,并在交变载荷作用下进一步扩展,进而最终导致疲劳断裂。     

Development aid: The moral obligation to innovation

The prominent, though not exclusive, role of basic needs strategies to attain ethically acceptable development goals raises the question of the ability of development agencies to find and employ basic needs strategies. The obligation to prevent severe human suffering leads to the obligation to employ basic needs strategies to attain basic needs goals. The history of failure by development agencies in finding and employing basic needs tools leads to a further obligation to cultivate bureaucratic environments which foster profound innovation. This requires not only new tools but also new bureaucratic behaviour. An understandable obstacle to simultaneously technological and bureaucratic innovation lies in the tension between responsible behaviour and behaviour promoting fundamental change. Since this tension is based on the unpredictability of creative change, a series of axioms and corollaries which reduce the unpredictability is given. They include: (1) an obligation to seek innovation; (2) a clear statement of basic needs goals and intent to use some basic needs tools; (3) increase in effective knowledge of the poor and their survival strategies; (4) bureaucratic learning flexibility; (5) participatory development and allied emphasis on sustainable resource technologies. The embodiment of these in the learning process approach is illustrated.     

无铰拱形泥石流拦挡坝研究

在泥石流防治工程中，拦挡坝是应用得比较广泛的一种措施。利用土木建筑中的拱结构形式，结合锚杆技术，引入了无铰拱形拦挡坝的概念。在狭窄河谷中，采用无铰拱形坝既可以改善坝体的工作环境，提高其承载能力，又可以减少材料用量，从而降低造价。针对无铰拱形坝的受力特性，进行了分析，提出了加强坝体、实现无铰的构造措施。