喷丸强化技术在某型作动筒延寿修理中的应用

目的将某型作动筒的寿命由6000±150起落延长至12 000±150起落。方法采用喷丸强化技术对作动筒的主要承力零件进行喷丸强化处理,提高零件的抗疲劳和抗应力腐蚀性能。通过疲劳寿命试验验证对比喷丸强化处理前后典型零件和作动筒的寿命指标是否达到了预期目标。结果喷丸强化处理前的3件前耳环螺栓试验循环次数均未超过1.8×10~6即断裂,喷丸强化后达到3.6×10~6时仍未断裂。喷丸强化处理后的4件主耳环螺栓与喷丸强化处理前对比,断裂时的试验循环次数均有不同程度的提高,均值寿命比值大于2.36。喷丸强化处理前后的主前作动筒疲劳寿命试验达到预期的循环次数时,均没有出现断裂或者损坏。结论喷丸强化处理能有明显提高作动筒的抗疲劳和抗应力腐蚀性,强化处理后的零件疲劳寿命能够超过处理前的2倍,可以采用喷丸强化技术延长作动筒的使用寿命。     

表面喷丸对Aermet100钢耐蚀性影响

目的 探究表面喷丸处理对于Aermet100钢耐蚀性能的影响。方法 借助显微观察、电化学测量及XRD分析等手段,开展喷丸与未喷丸2类A100钢试件的中性盐雾试验。结果 腐蚀形貌上,两者腐蚀表面变化均为先出现红褐色物质,后出现红棕色与绿色絮状物,在出现变化的时间上相差约1个周期。随着腐蚀时间增长,XRD衍射峰发生右移,2类试件XRD结果均在144 h变化明显。中性盐雾试验电化学结果与海洋环境下电化学结果在溶液电阻、腐蚀产物电阻和腐蚀反应电阻上均有差异,自腐蚀电位略低,自腐蚀电流则低了2个数量级。结论 两者腐蚀现象规律一致,XRD衍射峰右移表明试件晶格参数变小。2类试件腐蚀速率呈现增加到减缓再到增加的趋势。喷丸能明显提高A100钢的耐蚀性。     

基坑工程边坡滑移事故分析及微型桩在加固补强中的应用

以某高层住宅楼深基坑浆喷桩 喷锚网支护部分土体失稳为例,分析了事故的原因,阐述了采用微型桩在工程抢险加固中的作用,为类似工程提供可借鉴的方法。     

车辆悬架螺旋弹簧断裂失效行为研究

目的 判定车辆悬架螺旋弹簧失效的原因,提出改进措施.方法 通过分析和测试其化学成分、氢含量、非金属夹杂物、力学性能、金相组织、断口形貌等,研究车辆悬架螺旋弹簧的失效行为.结果 试件弯曲变形内侧的剪切应力值最大,容易引起应力集中.材料最后断裂区为韧窝和沿晶的混合断裂,且断后伸长率偏低.喷丸并未完全去除脱碳层及表层的其他原始缺陷,表层形成疲劳缺陷的可能性增高.喷丸造成螺旋弹簧表层存在较深的凹坑,凹坑边缘形成明显凸起棱边,引起应力集中,且材料表层存在折叠缺陷.在循环应力作用下,凹坑处折叠缺陷端部首先成为裂纹萌生点,在循环应力作用下,裂纹持续扩展,最终疲劳断裂.结论 减小钢丸粒径,降低喷丸压力,以避免过深的凹坑及尖锐的凸起棱边,并适当增加喷丸过程的表层去除深度;调整热处理工艺,适度降低材料强度、提高韧性,使断后伸长率大于10％.改进轧制工艺,消除材料的折叠缺陷,加强材料缺陷检测.     

喷丸强化对超高强度钢耐腐蚀性能的影响

目的提高舰载机结构疲劳关键部位的主体材料超高强度钢的耐蚀性能。方法基于实测的环境数据编制加速腐蚀试验环境谱,针对喷丸和未喷丸超高强度钢试验件在实验室条件下开展加速腐蚀试验,从宏观/微观形貌、质量损失、腐蚀速率和表面粗糙度等方面表征腐蚀行为,分析讨论喷丸强化对超高强度钢耐腐蚀性能的影响。结果超高强度钢腐蚀初期为局部点蚀,然后转变为全面均匀腐蚀。喷丸强化延缓了腐蚀形态转变的时机,喷丸试验件腐蚀速率约为未喷丸试验件的75%,加速腐蚀当量为3 a,未喷丸和喷丸试验件表面平均粗糙度分别为5.67mm和4.16mm,前者为后者的1.36倍。结论通过质量损失率、腐蚀速率和表面粗糙度的对比分析知,喷丸强化明显提高了超高强度钢的耐腐蚀性能。     

Long-term effects of lead poisoning on bone mineralization in vultures exposed to ammunition sources

Long-lived species are particularly susceptible to bioaccumulation of lead in bone tissues. In this paper we gain insights into the sublethal effects of lead contamination on Egyptian vultures (Neophron percnopterus). Our approach was done on the comparison of two populations (Canary Islands and Iberian Peninsula) differing in exposures to the ingestion of lead ammunition. Blood lead levels were higher in the island population (Canary Islands range: 5.10-1780 μg L⁻¹n = 137; Iberian Peninsula range: 5.60-217.30 μg L⁻¹n = 32) showing clear seasonal trends, peaking during the hunting season. Moreover, males were more susceptible to lead accumulation than females. Bone lead concentration increased with age, reflecting a bioaccumulation effect. The bone composition was significatively altered by this contaminant: the mineralization degree decreased as lead concentration levels increased. These results demonstrate the existence of long-term effects of lead poisoning, which may be of importance in the declines of threatened populations of long-lived species exposed to this contaminant.     

校园一次性废电池回收关键环节的问卷调研

如何从分散的大量用户手中回收一次性废电池是目前一次性废电池回收体系构建中的关键环节。文章采用问卷调查方法,以华东师范大学中山北路校区在校本科生为对象,研究了针对校园大学生用户回收一次性废电池环节中的存在问题和解决。提出了"以旧换新"的回收方式,初步确定了该方式运行所需的几个关键参数:回收的"旧新电池回收比例"为5:1,回收地点在各宿舍管理员处,回收时间为每月定期进行一次。文章结果对于构建废电池回收体系具有一定的参考意义。     

The environmental and ethical implications of lead shot contamination of rural lands in North America

Lead shot deposited in fields and woodlands near shooting rangesand intense, upland, hunting adds an enormous tonnage of lead toenvironments, worldwide. This contamination is not remedied bybanning lead shot use only for waterfowl hunting. Lead pelletsdisintegrate extremely slowly, during which time they may beingested from the soil by wild birds, livestock, or silage-makingmachinery, and cause sublethal or fatal lead poisoning. Leadpellet corrosion products contaminate soil, surface waters, andground waters, often exceeding permissible levels. Plants do notconcentrate much lead from the soil, except when grown in acidicsoils of heavily-contaminated shooting ranges. Inheavily-contaminated sites, earthworms ingest leadcompounds which are bioaccumulated in higher consumersof food webs. Non-toxic substitutes made from steelor bismuth are available internationally and areeffective for all types of hunting and targetshooting. Many nations are slow to require their use,despite the marked awareness of the problems of leadshot contamination and toxicosis. This is due tohunters and international sport shooting organizationsopposing the use of non-toxic substitutes and overtemphasis by government agencies on the burden ofscientific proof for every situation, rather thantaking preventative action according to thePrecautionary Principle. The ethical approach ofDenmark and The Netherlands, which banned all uses oflead shot, is advocated as a precedent for othernations to adopt.     

基于SSD网络的电梯内电动自行车检测研究*

为减少因电动自行车违规操作而造成的消防安全事故,杜绝电动自行车进电梯的违规行为,基于深度学习SSD目标检测网络,使用VGG16、EfficientNet、MobileNet 3种主干网络,研究SSD网络对电梯内电动自行车检测的可行性,分析比较3种网络的检测效果,并提出基于双摄的检测方法,进一步提高电梯场景下检测准确度,减少误检误报警。研究结果表明:SSD检测网络对电梯内电动自行车检测效果良好,其中SSD_MobileNet网络更适用于工业领域,双摄检测方法的检测准确率均大于90%。     

后处理对离子镀铝涂层腐蚀性能的影响研究

研究了喷丸和化学氧化后处理方法对离子镀铝涂层微观形貌和耐腐蚀性能的影响,并对离子镀铝、电镀锌、低氢脆镀镉、氯化铵镀镉等4种涂镀层的耐腐蚀性能和与铝合金的接触腐蚀进行了对比研究.研究表明通过喷丸可有效地减少镀层孔隙率,提高镀层致密度;喷丸 化学氧化,化学氧化后的离子镀铝层具有良好的耐腐蚀性能;离子镀铝涂层耐腐蚀性能大大高于锌镀层,但低于同等厚度的镉镀层,离子镀铝涂层与7B04铝合金的接触腐蚀性能略优于其他3种镀层.