Analysis of multiple activity manual materials handling tasks using A Guide to Manual Materials Handling

Manual handling of materials continues to be a hazardous activity, leading to a very significant number of severe overexertion injuries. Designing jobs that are within the physical capabilities of workers is one approach ergonomists have adopted to redress this problem. As a result, several job design procedures have been developed over the years. However, these procedures are limited to designing or evaluating only pure lifting jobs or only the lifting aspect of a materials handling job. This paper describes a general procedure that may be used to design or analyse materials handling jobs that involve several different kinds of activities (e.g. lifting, lowering, carrying, pushing, etc). The job design/analysis procedure utilizes an elemental approach (breaking the job into elements) and relies on databases provided in A Guide to Manual Materials Handling to compute associated risk factors. The use of the procedure is demonstrated with the help of two case studies.     

Calculation of average coding efficiency based on subjective quality scores

The Bjøntegaard model is widely used to calculate the coding efficiency between different codecs. However, this model might not be an accurate predictor of the true coding efficiency as it relies on PSNR measurements. Therefore, in this paper, we propose a model to calculate the average coding efficiency based on subjective quality scores, i.e., mean opinion scores (MOS). We call this approach Subjective Comparison of ENcoders based on fItted Curves (SCENIC). To consider the intrinsic nature of bounded rating scales, a logistic function is used to fit the rate–distortion (R–D) values. The average MOS and bit rate differences are computed between the fitted R–D curves. The statistical property of subjective scores is considered to estimate corresponding confidence intervals on the calculated average MOS and bit rate differences. The proposed model is expected to report more realistic coding efficiency as PSNR is not always correlated with perceived visual quality.     

Evolution of superpeer topologies — An analytical perspective

In superpeer based networks, resourceful peers (having high bandwidth and computational resources) are discovered through the process of bootstrapping, whereby they get upgraded to superpeers. However, bootstrapping is influenced by several factors like limitation on the maximum number of connections a peer can have due to bandwidth constraints, limitation on the availability of information of existing peers due to cache size constraints and also by the attachment policy of the newly arriving peers to the resourceful peers. In this paper, we derive closed form equations that model the effect of these factors on superpeer related topological properties of the networks. Based on the model, we show that existing bootstrapping protocols can lead to a situation where only a small fraction of the resourceful peers gets converted to superpeers, i.e., a large fraction of them remain underutilized; we later validate this statement using real Gnutella snapshots. We observe that as a node attachment policy, newly arriving peers must use a combination of random and preferential attachment strategy so as to ensure proper utilization of the resourceful peers. We also show that the cache parameters must also be suitably tuned so as to increase the fraction of superpeers in the network. Finally, we show that in real Gnutella networks the degree distribution generated using our models suitably fits the corresponding empirical values.     

降低用棉单耗的生产体会

探讨降低净用棉单耗的途径和措施。以JC 9.7tex纱为例,通过在各项专业及生产技术管理工作方面采取一系列措施,结果获得了良好的降耗效果。认为,降低净用棉单耗是一项全面系统的管理工作,首先应发挥各职能部门专业管理作用,做好原棉采购、收付检验、配棉、混棉、拣花间回花、落棉、下脚的管理以及月末盘存和数据统计工作。各生产工序在稳定成纱质量的前提下,以减少落棉、回花,提高制成率为主线,做好工艺、设备、操作等各方面的基础管理工作,最终能够取得良好的降耗效果。     

Komplementäre Modellierung in der Fluidverfahrenstechnik

Optimization of technological processes depends on the relevant process design, properly selected column internals and sufficient understanding of the process behavior. This can only be achieved with the help of accurate and reliable process models. Along these lines, the present article suggests a new modelling concept – complementary modeling – for a large class of fluid engineering processes. Due to diversity of process conditions and criteria, it is impossible to develop a unified modelling approach. Instead, an efficient combination of different modeling approaches is advantageous. The complementary modeling is discussed in detail and illustrated with several case studies.     

Physiological workload reactions to increasing levels of task difficulty

The sensitivity of physiological measures to mental workload was investigated in a flight simulator. Twelve pilots had to fly through a tunnel with varying levels of difficulty. Additionally, they had to perform a memory task with four levels of difficulty. The easiest memory task was combined with the easiest tunnel task and the most difficult memory task with the most difficult tunnel task. Between the tunnel tasks, subjects had to fly a pursuit task in which a target jet had to be followed. Rest periods before and after the experiment were used as a baseline for the physiological measures. Mental workload was measured with heart period, continuous blood pressure, respiration and eye blinks. Several respiratory parameters, heart rate variability, blood pressure variability and the gain between systolic blood pressure and heart period (modulus) were scored. All measures showed differences between rest and flight, and between the pursuit and the tunnel task. Only heart period was sensitive to difficulty levels in the tunnel task. Heart rate variability increased when respiratory activity around 0.10 Hz increased, which occurred often. The modulus was hardly influenced by respiration and therefore appears to be a better measure than heart rate variability. Among the respiratory parameters, the duration of a respiratory cycle was the most sensitive to changes in workload. The time in between two successive eye blinks (blink interval) increased and the blink duration decreased as more visual information had to be processed. Increasing the difficulty of the memory task led to a decrement in blink interval, probably caused by subvocal activity during rehearsal of target letters. The data show that physiological measures are sensitive to mental effort, whereas rating scales are sensitive to both mental effort and task difficulty.     

A multi-layered dual-band on-body conformal integrated antenna for WBAN communication

This article presents a dual-band, multi-layered on-body conformal metamaterial (MTM) integrated antenna for Wireless Body Area Network (WBAN) communication. The frequency bands range from 3.2 GHz to 3.5 GHz and 3.9 GHz to 4.3 GHz. A zero-reflection-phase based MTM comprises of the 2 × 2 array of H-shaped unit-cell is installed beneath the monopole antenna to suppress the back radiations, and enhance the gain. The characterization of the unit-cell is done in terms of its reflection and transmission characteristics, refractive index, and material characteristics. The integration of the MTM brings down the peak 1-g-averaged SAR to 0.174 W/kg and 0.207 W/kg at the respective bands of the conformal configuration for a body-antenna separation of 1 mm. The proposed configuration proffers peak realized antenna gain of 4.54 dBi and 4.71 dBi, and Front to Back Ratio (FBR) of 11.79 dB and 12.98 dB at the respective frequency bands. The performance of the proposed antenna is rigorously analyzed against structural deformation, operating frequency, gain, and FBR. The measured performance of antenna agrees well with that of simulated results.     

Degradation of the antimicrobial triclocarban (TCC) with ozone

Triclocarban (TCC) has been used as an antimicrobial compound for many decades due to its sanitising properties. Recent studies showed that TCC is toxic and causes disruption to the endocrine system. In this work, ozone oxidation of TCC was studied in 70% acetonitrile:30% water solutions. Ozone degraded TCC effectively and the reaction rates increased substantially with ozone gas concentration, pH and temperature. Second-order-reaction kinetics was suitable to describe the chemical reaction. The effect of temperature was described by the Arrhenius equation and the activation energy was found equal to 31.0 kJ/mol. The stoichiometry of the reaction was one and the value of the rate constant at pH 7 was 5 × 10³ M⁻¹ s⁻¹.     

短波通信中基于自适应帧长的数据速率变化改进算法

为解决传统数据速率变化（DRC）传输算法中因速率震荡造成的高误码率（BER）问题，提出一种基于自适应帧长（AFL）的DRC改进传输算法。首先，在初始化阶段，根据当前信道的参数和以往经验值信息确定初始传输的帧长和传输速率，并进行数据传输。然后，当检测到传输过程中连续两个相同长度帧发送成功后，开始增加帧长；若出现重发帧连续两次重传失败的情况，则在下次传输时将帧长减半。最后，结合当前的帧长计算误帧率，若该值小于预设的阈值，则提高数据传输速率。与RapidM DRC算法相比，该算法的链路平均BER降低了个1.8百分点，链路连通率提高了11个百分点。实验结果表明，所提算法基本消除了速率震荡的现象，能够提高短波通信系统的通信能力。     

恩斯林装置的改进及吸水率影响因素分析

吸水率是球团用膨润土的重要指标,直接影响造球效应和生球质量的稳定。研究表明,恩斯林装置中市售毛细管内径的差别,对膨润土吸水率的测定带来较大的误差。测定方法参照《非金属矿物化性能测试规程》。对恩斯林装置进行改进,使用2 ml的移液管代替毛细管,测试体积直读;并对试验装置进行固定、水平检测,试验条件进行优化,并分析了影响膨润土吸水率的几个因素。实验测试可以达到准确、简便检测的目的。