某转管自动机停射故障分析

根据某自动机工作原理和试验情况,分析故障现象,建立了各故障现象间的关系框图,通过详细推理分析和验证,还原故障发生过程。经多方排查验证,最终确定故障原因为左供弹接口和进弹机交接处有负间隙现象,高速进弹时碰撞炮弹药筒口部使外形异常,推弹时受阻,引起后续相关零部件工作异常,进而造成连锁式损坏和最终停射故障。经分析和多次模拟试验,改进优化供、进弹交接处间隙,通过多门炮射击试验验证,再未出现类似停射故障。     

Assessment of the static fit of automobile lap-belt systems on front-seat passengers

While automobile seat belts are recognized as reducing injury in frontal collisions, the lap belt can cause injury to the abdominal contents during impact. A lap belt which is malpositioned, i.e., above the anterior superior iliac spines (ASIS) of the pelvis before impact, is suggested as a causative factor in many of these injuries. A questionnaire was completed by 198 adult passengers on lap-belt fit as well as vehicle, anthropometric and behavioural factors. All measures were self-reported. The fit of automobile seat belts was also investigated in the laboratory to determine some of the factors thought important in the pre-impact position of the lap belt. Seven factors, subject size, subject sitting posture, clothing thickness, vehicle configuration, vehicle seat position, seat back angle and the handling of the belt by the occupant, were assessed on 51 subjects sitting in six simulated vehicles. The sample purposely included a disproportionate number of tall, short, heavy and thin subjects.

The questionnaire responses indicated that a high proportion (49%) of lap belts were found to be malpositioned in a normal sitting posture. Moving around in the seat, especially slouching, greatly increased the proportion of malpositions. It was noteworthy that wearing a heavy winter coat did not cause belt malposition. A high incidence of malpositioned lap belts was also found in the laboratory study with 42% of the belts having their centre-lines above the ASIS and 89% having part of the belt overlying the ASIS in a normal upright seated position with the seat in the middle of its fore/aft movement. Slouching in the seat significantly increased this proportion. The malposition rate was adversely affected by a forward seat position in a significant manner. There was a large increase in the malposition rate when the occupant attached the belt compared to when the experimenter attached it, with malposition rates of 43% and 19% respectively in the rearmost seat position. There was no statistically significant effect of clothing thickness on belt fit. Although statistically significant correlations between belt inclination and malposition were found, no clear-cut belt-angle existed above which satisfactory fit existed.     

谈南京某项目混凝土跳仓法施工

通过研究南京某项目的环境特征及现场施工条件,对混凝土跳仓法施工的可行性进行了分析,并阐述了其施工原理,同时对跳仓法施工分仓划分与施工方法作了介绍,指出使用跳仓法施工可保证工程底板不出现有害贯穿性裂缝。     

输送带用钢丝绳生产及技术进步

介绍输送带用钢丝绳的主要生产控制及使用要求。从捻制质量、结构选择、力学性能以及粘合力和镀层质量控制等方面介绍输送带用钢丝绳的生产工艺控制以及各生产工序质量控制的注意事项,指出钢丝绳弯曲疲劳、输送带张紧装置造成胶带张力过大和张力分布不均匀、外力过大、腐蚀、异物损伤以及接头抽丝是输送带用钢丝绳使用过程中断裂的主要原因,保证钢丝绳储存质量和改善钢丝绳接头工艺有助于减少输送带生产过程中的钢丝绳消耗。对输送带用钢丝绳的技术进步做了展望。     

PLC在皮带输送机控制中的应用

结合皮带输送机的控制实例,阐述了PLC控制系统的软硬件设计方法,并重点分析了顺序功能图的设计方法     

Differences in lithospheric structures between two sides of Taihang Mountain obtained from the Zhucheng-Yichuan deep seismic sounding profile

A 2-D model of lithospheric velocity structures in the southern part of the North China Craton was obtained using data from the Zhucheng-Yichuan deep seismic sounding profile.Results show that there are great differences in lithospheric structures between two sides of Taihang Mountain.In the eastern region,the lithosphere is thinner,with a thickness of about 70-80 km,while in the western region,the thickness is 85-120 km.There is a jump of the lithospheric thickness across Taihang Mountain gravity anomaly b...     

Polymers in High Performance Structures

Abstract

The continuing need for “high performance” in the application of polymers will provide a driving force for modification of polymers to achieve these characteristics. Some specific considerations with respect to polymers, properties and uses are presented as possible guides to future developments.     

组合式火箭爆破器系统飞行性算法研究

为提高爆炸带的展直率,确保火箭爆破器的破障效果,建立二维有限质点模型对火箭爆破器系统的飞行特性进行研究。根据力学方程、运动方程和几何连续方程,通过时间差分法对各质点的力学参数进行数值计算,并结合实验工况对火箭爆破器系统在空中飞行的力学特性进行计算分析。结果表明:在主动段中,火箭拖拽爆炸带加速运动,爆炸带保持直线拉直状态;爆炸带全部拉出后,由于阻力伞的作用,爆炸带的内力较大,仍能维持在展直状态;进入被动段后,随着火箭及爆炸带速度的下降,阻力伞对爆炸带的拉力随之下降,爆炸带在越过最高点后,下落的阶段容易发生弯曲。     

一次成型环状输送带增强骨架研发

在机上织造成环、无需机下接头的输送带增强骨架,称为一次成型环状增强骨架。环状增强骨架由于不存在接头,具有带体厚度波动小、噪声低、力学性能优等特点。将织物组织结构参数相同的环状增强骨架、传统增强骨架制备成输送带,对两者的厚度波动、噪声和拉伸强度进行试验和对比分析。结果表明,环状增强骨架输送带的厚度波动小于传统增强骨架输送带,噪声低于传统增强骨架输送带,力学性能明显优于传统增强骨架输送带。