Work/rest cycles in railroad operations: effects of shorter than 24-h shift work schedules and on-call schedules on sleep

The current study examined the frequency with which shorter than 24-h work/rest cycles occur in locomotive engineer work schedules, and what effects these work/rest cycles had on sleep quantity and sleep quality. The results indicated that shorter than 24-h work/rest cycles occurred in 33.6% of the work days reported by 198 locomotive engineers. In addition, the shorter than 24-h work/rest cycles occurred more frequently in work schedules that created an on-call work system, such as road pool turn and extra board assignments, than in work schedules that used more predictable or regular work times, such as regular road assignments and yard/local work. As would be expected, when engineers worked shorter than 24-h work/rest cycles, they reported less sleep and poorer sleep than under the longer than 24-h work/rest cycles. Similarly, on-call work assignments resulted in less sleep and poorer sleep than regular work assignments. These results indicate that specific aspects of the work schedules used in railroad operations, particularly on-call operations that result in shorter than 24-h work/rest cycles, can lead to increased sleep-related problems. Although the North American railroad industry is making significant changes in on-call operations to minimize sleep-related problems from on-call schedules, better fatigue-related models validated within the railroad industry are needed.     

可重构移位单元的设计与实现

在对称密码算法中移位操作使用频率非常高,尤其是在密钥生成中的应用。但各种算法之间的移位位宽和移位长度并不一致,所以现有的密码处理系统中还没有一个通用的移位单元支持所有对称密码算法的移位操作。本文在研究了多种对称密码算法的基础上,分析了高效灵活实现移位单元的方法,并提出了一种基于多级网络的可重构移位单元,它可以支持4/8/28/32/128-bit移位位宽以及可变移位长度的移位操作。此单元的设计与实现,不仅增强了密码处理单元的通用性,还使得可重构密码芯片的实现成为可能。     

在Excel97中"Shift"键的几点使用技巧

1.快速选定多个工作表利用“Shift”键可以选定多个工作表。我们可以选定若干个工作表使其成为“工作表组”,可以选定相邻的工作表 ,也可以选定不相邻的工作表。要选定相邻的工作表 ,必须先单击想要选定的第一张工作表的标签 ,按住“Shift”键 ,然后单击最后一个工作表的标签 ,这时会看到在活动工作的标题栏上出现“工作表组”的字样。2 .快速移动数据区域利用“Shift”键可将一块数据区域移动到工作表中的任意位置。方法是 :选中需移动的数据区域 ,按下“Shift”键 ,再将鼠标移到数据区域的边界。按住鼠标左键拖动数据区域向目标位置移动…     

School timetabling for quality student and teacher schedules

The school timetabling problem, although less complicated than its counterpart for the university, still provides a ground for interesting and innovative approaches that promise solutions of high quality. In this work, a Shift Assignment Problem is solved first and work shifts are assigned to teachers. In the sequel, the actual Timetabling Problem is solved while the optimal shift assignments that resulted from the previous problem help in defining the values for the cost coefficients in the objective function. Both problems are modelled using Integer Programming and by this combined approach we succeed in modelling all operational and practical rules that the Hellenic secondary educational system imposes. The resulting timetables are conflict free, complete, fully compact and well balanced for the students. They also handle simultaneous, collaborative and parallel teaching as well as blocks of consecutive lectures for certain courses. In addition, they are highly compact for the teachers, satisfy the teachers’ preferences at a high degree, and assign core courses towards the beginning of each day. Dr. Birbas is currently the Director for Primary and Secondary Education in the Region of Western Greece.     

Reply to Folkard

Abstract

The duty and rest periods of aircrew operating the polar route from London via Anchorage were recorded during five schedules which involved 1-, 2- or 3-day sojourns in Japan. Sleep throughout each schedule was fragmented, with naps before duty and short sleeps after arrival at a new location. Sleep disturbance rather than cumulative sleep loss appeared to be the overriding problem, and the shorter schedules had the most marked disturbances in sleep during the trip and during the immediate recovery period. Electroencephalographic studies are necessary to confirm these observations, and information on circadian rhythmicity is needed to define the circumstances which lead to persistence of sleep disturbance on return to Europe.     

液压换档离合器带排转矩研究

本文针对车辆动力换档传装置普遍采用的液压换档离合器,分析研究了其在分离状态下所产和珠带排转矩,讨论了转速差、润滑油温度、润滑油流量和采用蝶形钢片对带排转矩的影响。     

PLL DEMODULATION TECHNIQUE FOR M-RAY POSITION PHASE SHIFT KEYING

The paper presents a kind of transmission system which employs M-ary Position Phase Shift Keying (MPPSK) to send data and Phase Locked Loop(PLL)based techniques for data retrieve.With a single PLL,MPPSK demodulation is achieved,as well as carrier recovery and symbol synchronization.Firstly,MPPSK modulation method is briefly introduced.2PPSK's PSD expression is given with its optimization result.Orthogonal Phase Detector (PD) and static threshold are used for the purpose of wider phase range and simplicity in demodulation.The data rate is alterable,which is 4.65 kbps for 2PPSK and 9.3 kbps for 4PPSK in the paper.Then some indicative comparisons in Signal to Noise Ratio Symbol Error Rate (SNR-SER) are made among 2PPSK,3PPSK and 4PPSK,of which 4PPSK has proved to be optimal in ten slots each symbol conditions.And finally,it is demonstrated by system simulations that lower than 10-4 Symbol Error Rate(SER)performance can be obtained at 13 dB symbol SNR.     

一种嵌入式实时跟踪系统的设计与实现

设计了一种视频跟踪器,它以高性能DSP芯片TMs320Vc5416作为中央处理器,结合现场可编程门阵列(FPGA)构成外围电路逻辑控制,搭建了硬件跟踪平台,并在此系统中实现了用Kalman滤波估计目标位置和Mean Shift算法跟踪的目标位置自适应加权求和,作为目标最终跟踪结果的跟踪算法,有效减少了相同颜色背景的干扰.实验结果表明,本系统具有良好的跟踪性能,满足实时性要求.     

一种由移位数列生成GMW序列和级联GMW序列的新算法

本文提出了一种新的根据移位数列生成GMW序列和级联GMW序列的构造方法,该方法简化了传统的GMW序列和级联GMW序列的构造方法,大大提高了生成效率,并验证了其可行性.     

一种面向混沌时间序列预测的虚拟特征提取算法

针对混沌时间序列预测问题,该文提出一种虚拟特征提取算法,以提高其预测精度。首先,采用平移不变小波变换,提取出混沌时间序列的细节和光滑子层信息。然后,将混沌序列线性与非线性特征从加和关系推广到函数关系。最后,利用小波子层信息给出一种新颖的虚拟特征表达,以用于预测实验。采用经典的Mackey-Glass仿真数据,以及美国密西西比河实测径流流量数据实验表明,该文方法提高了预测精度,从而也验证了该文提出的虚拟特征提取算法在混沌时间序列预测上的有效性。同时,也可为控制、水文、气象等领域的混沌现象决策提供参考。