Risk of slaughterhouse workers developing work-related musculoskeletal disorders in different organizational working conditions

Job rotation is defined as workers rotating between tasks with different exposure levels and occupational demands. The aim of the present study was to analyze the risk factors for the development of upper-limb work-related musculoskeletal disorders (UL-WMSDs) in poultry slaughterhouse workers as well as compare the score of the OCRA Checklist in different organizational working conditions. In this cross-sectional study, 118 workers were involved, 68 women (32.3 ± 10.7 years) and 50 men (29.5 ± 10.5 years). Three organizational configurations (“without job rotation”, “with job rotation – tasks >1h” and “with job rotation - tasks <1h”) were evaluated using the OCRA Checklist method, totaling 36 tasks and 28 job rotation schemes composed of 2–3 tasks. The OCRA score of the right upper limbs (17.8 ± 3.2) was significantly higher (p = 0.046) relative to the left upper limbs (16.4 ± 3.6). The median score was significantly lower in the “with job rotation - tasks <1h” condition (18.6) when compared to the “job rotation – tasks >1h” (19.4) (p < 0.001) and the “without job rotation” (19.0) (p = 0.038) conditions. However, there was no significant difference between the condition “with job rotation - tasks >1h” and “without job rotation” (p = 0.155). Thus, job rotations with intervals <1h reduced the risk of developing UL-WMSDs. Job rotations with <1 h intervals in poultry slaughterhouses are recommended along with further studies to verify the effectiveness of rotations with more than two tasks, involving mild or non-repetitive tasks.     

基于残差决策的自动飞行控制系统远程实时故障诊断

针对自动飞行控制系统结构复杂、关联部件众多,发生故障时诊断时间长,从而影响飞机运行效率的问题,提出一种基于飞机通信寻址报告系统(ACARS)的远程实时故障诊断方案。首先,分析自动飞行控制系统的故障特点,设计搭建检测滤波器;然后,利用ACARS数据链实时发送的自动飞行控制系统的关键信息进行相关部件的残差计算,并根据残差决策算法进行故障诊断及定位;最后,针对不同故障部件残差间的差异大、决策门限无法统一的缺点,提出基于二次差值的残差决策改进算法,减缓了检测对象的整体变化趋势,降低了随机噪声和干扰的影响,避免了将瞬态故障诊断为系统故障的情况。实验仿真结果表明,基于二次差值的改进残差决策算法避免了多决策门限的复杂性,在采样时间为0.1 s的情况下,故障检测所需时间大约为2 s,故障检测时间大幅降低,有效故障检测率大于90%。     

Industrial sugar beets to biofuel: Field to fuel production system and cost estimates

Specialized varieties of sugar beets (Beta vulgaris L.) may be an eligible feedstock for advanced biofuel designation under the USA Energy Independence and Security Act of 2007. These non-food industrial beets could double ethanol production per hectare compared to alternative feedstocks. A mixed-integer mathematical programming model was constructed to determine the breakeven price of ethanol produced from industrial beets, and to determine the optimal size and biorefinery location. The model, based on limited field data, evaluates Southern Plains beet production in a 3-year crop rotation, and beet harvest, transportation, and processing. The optimal strategy depends critically on several assumptions including a just-in-time harvest and delivery system that remains to be tested in field trials. Based on a wet beet to ethanol conversion rate of 110 dm³ Mg⁻¹ and capital cost of 128 M$ for a 152 dam³ y⁻¹ biorefinery, the estimated breakeven ethanol price was 507 $ m⁻³. The average breakeven production cost of corn (Zea mays L.) grain ethanol ranged from 430 to 552 $ m⁻³ based on average net corn feedstock cost of 254 and 396 $ m⁻³ in 2014 and 2013, respectively. The estimated net beet ethanol delivered cost of 207 $ m⁻³ was lower than the average net corn feedstock cost of 254–396$ m⁻³ in 2013 and 2014. If for a mature industry, the cost to process beets was equal to the cost to process corn, the beet breakeven ethanol price would be $387 m^-3 (587 $ m⁻³ gasoline equivalent).     

Large piezoelectricity and potentially activated polarization reorientation around relaxor MPB in complex perovskite

Improving piezoelectric performance is always favorable to further enhance the sensitivity and accuracy of piezoelectric devices. Here, a complex piezoelectric system of Pb(Ni_1/3Nb_2/3)O₃-Pb(Yb_1/2Nb_1/2)O₃-Pb(Hf_0.1Ti_0.9)O₃ is designed and investigated in detail. Optimized piezoelectric response of ～ 880 pC/N is achieved at the composition of 0.51PNN-0.09PYN-0.40PHT. The characterization of TEM and In-situ high-energy synchrotron diffraction indicate that nanodomain growth and microdomain switching occurs in succession at around coercive electric field. Most interestingly, the coexisted tetragonal and rhombohedral-like phase transforms into multiple monoclinic-like phases with polarization vectors aligned as close to the electric field direction as possible under the strong electric field. The enhanced polarization instability in this complex morphotropic phase boundary sample should be ascribed to the strong local heterogeneity. The novel polarization rotation behavior found in this work would be important guidance for designing high-performance piezoceramics.     

Improving weld formability by a novel dual-rotation bobbin tool friction stir welding

A novel dual-rotation bobbin tool friction stir welding (DBT-FSW) was developed, in which the upper shoulder (US) and lower shoulder (LS) have different rotational speeds. This process was tried to weld 3.2 mm thick aluminum-lithium alloy sheets. The metallographic analysis and torque measurement were carried out to characterize the weld formability. Experimental results show that compared to conventional bobbin tool friction stir welding, the DBT-FSW has an excellent process stability, and can produce the defect-free joints in a wider range of welding parameters. These can be attributed to the significant improvement of material flow caused by the formation of a staggered layer structure and the unbalanced force between the US and LS during the DBT-FSW process.     

VRDS装置增加上流式反应器的技术分析

介绍了世界上第1套上流式反应器技术(UFR)在胜利炼油厂渣油加氢脱硫(VRDS)装置的生产运行情况。结果表明:UFR技术可以极大地优化VRDS装置的运转,减少装置运转的苛刻度,有效地延长装置运转周期,提高装置的经济效益。     

RHT系列渣油加氢催化剂在胜利炼油厂VRDS装置上的工业应用

介绍由北京石油化工研究院研制、开发、用于渣油加氢装置固定床反应器的RHT系列催化剂在胜利炼油厂VRDS装置的首次工业应用情况。该催化剂采用自行开发的级配路线,较好地结合了脱金属剂、脱硫剂、脱氮剂的性能特点,使整个运行周期的催化剂活性和稳定性达到较好地匹配,已达到同类进口催化剂的水平。     

摩擦换向抽油机悬点运动分析计算

摩擦换向抽油机采用开关磁阻电动机或变频调速电动机,其特点是可以频繁双向旋转,带动摩擦轮正反转,实现光杆的上行下行。该抽油机运动特点与游梁式抽油机运动特点有较大区别,文章分析了摩擦换向抽油机的运动特点,给出了该机悬点位移、速度、加速度的计算方法。