Relationships between observed and perceived deviations from normative work procedures

Deviations from anticipated courses of events are often associated with accidents, while the effects of deviations that decrease productivity but do not obviously lead to human injury are less clear. A systemic approach to production and safety is introduced, and it is proposed that production deviations have effects that may lead to safety violations and personal injury. In addition, the relationship between observed and perceived production deviations from 12 senior (60–79 years old) males' routine work using three firewood processing machines is analysed. For simple machine work, perceived deviations were positively related to observed deviations per work cycle and inversely correlated to the perception of work efficiency. For more complex machine work it was more difficult to match observers' and operators' perceptions of deviations. Despite challenges in the production deviation concept, this approach offers a holistic understanding of the performance of human–machine-environment systems and complements assessments of deviations from safe working practice.     

边坡主要因素对强度折减法计算精度的影响

采用强度折减法和极限平衡法对粘土边坡进行稳定性分析,并将计算所得的安全系数加以对比,进行误差分析,通过研究粘聚力、内摩擦角、坡高和坡角等指标对计算精度的影响,揭示影响计算精度的主要因素和次要因素,为以后的数值模拟研究提供有利的参考。     

Analysis of spatial smoothing effect of short‐term fluctuation of global solar radiation based on data including quantization error

Photovoltaic (PV) systems are attracting attention as one of the promising countermeasures against global warming and the environmental issues. However, the generation output from PV systems is generally unstable and unpredictable. Therefore, large penetration of PV systems may cause some serious impacts on power system operation, such as load frequency control, voltage regulation, etc. Estimation of the influences of PV system installation is becoming important, but it requires simultaneous multipoint solar radiation measurements. The Japan Meteorological Business Support Center has provided 1‐minute meteorological data observed in Japan, but its solar radiation data includes quantization errors. This paper proposes a regeneration method for solar radiation data including quantization errors. It also analyzes the spatial smoothing effect of global solar radiation fluctuations. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(3): 55–63, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21274     

A second-order algorithm for curve orthogonal projection onto parametric surface

Repeated use of point projection to find the projection of a curve on a surface is rather inefficient as the iteration procedures in point projection is typically slow. A novel curve projection scheme is proposed for computing the orthogonal projection of a progenitor curve onto a parametric surface. Under this scheme, the projection curve is parameterized using the parameter of the progenitor curve. Differential geometric characteristics of the projection curve are analysed. A marching method with error adjustment is used to calculate the projection curve. Several examples are presented and comparisons are made to demonstrate the effectiveness of the proposed scheme.     

MIMO two-way relay channel with superposition coding and imperfect channel estimation

This paper deals with the superposition coding (SPC) scheme in multiple-input multiple-output two-way relay channels subject to imperfect channel estimation. In this scenario, two multiple antenna terminals, which are unable to communicate directly, exchange information with each other via a multiple antenna relay. We determine the impact of the channel estimation error degradation on the achievable rate region for two main SPC techniques: (a) SPC without channel state information (CSI) at the users, (b) SPC with an imperfect CSI at the users where a waterfilling power allocation is employed. We demonstrate that imperfect CSI significantly improves the achievable rate at low signal-to-noise ratios (SNRs) while it becomes less critical at high SNRs. In addition, a SPC power allocation technique that incorporates the average channel statistics and does not require any instantaneous CSI is also investigated. We show how the available power is split between the two bi-directional (superimposed) data flows in order to maximize the system performance and to support fairness as well as to maximize the achievable sum-rate.     

Perturbation sensitivity analysis of azimuth estimation of the acoustic source for the planar microphone array

Aiming at the requirements of quantitative analysis of the array scheme and positioning performance of a practical compact acoustic detection node system, the upper bound of the far-field azimuth estimation error for an arbitrary small-size planar array is derived and the four elements of the corresponding perturbation sensitivity factor with explicit physical significance are determined. It is proved that the perturbation sensitivity of the source direction-finding algorithm to the time difference of arrival (TDOA) estimates between microphones can be lowered obviously by means of increasing the number of distinct microphone pairs as well as employing spatially uniform distribution of array elements. Simulation results demonstrate that this study provides a quantitative approach to evaluating and comparing the azimuth estimation performance of different planar arrays.     

Knowledge domain states mapping concept for controller tuning in an interconnected power network

This paper presents novel power system stabilizers (PSS) tuning approach with particles swarm optimization (PSO) driven knowledge domain states mapping for multi area power system. Tuning of PSS parameters has been done by PSO technique offline at different operating conditions as load dynamics change. The objective function for PSS parameters tuning is integral time multiplied by absolute error (ITAE). The sets of tuned parameters at different operating conditions thus obtained are termed as knowledge domain. The process is viewed as knowledge domain mapping. The dynamical system response has been linked with states, and if there is any violation from desired limits, control action is initiated and thus retuned control parameters obtained straight away from the respective knowledge domain helps to provide quick response and precise damping of signals of interest. Proposed concept also demonstrates that if one controller (PSS) fails to stabilize the system at certain operating condition then another controller (UPFC) connected in the system acts as supplementary controller in automation which assists PSS functioning and thus entire system operation improves by way of modulating the signal dynamics at interface points which quickly damps oscillations. The system study has been performed on a sample six area power systems comprising of UPFC connected between area two and three and PSS to all areas. The proposed concept demonstrates auto tuning of PSS for quick oscillation damping as the operating conditions change and also under situations of PSS failure due to relatively larger perturbation, UPFC acts as supplementary controller by assisting the entire system PSS to recover ensuring stability.     

非对称成对载波多址信号的相位误差分析及幅度改进算法

针对由主站和小站信号同频混合而成的非对称成对载波多址（PCMA）信号解调问题，构建了一种实现此类信号解调的框架。参数估计是非对称PCMA通信系统在实现两路信号分离解调时不可或缺的环节，对于幅度参数估计精度问题，提出一种基于四次方法的搜索式幅度估计算法。首先建立非对称PCMA系统解调模型并作出基本假设，然后对不同假设下的相位误差进行对比并分析相位误差对幅度估计算法的影响，最后提出一种新的幅度估计算法。实验结果表明在相同信噪比（SNR）下，正态相位误差下的小站信号解调性能要劣于其均值条件下的解调性能。当误比特率（BER）在数量级为10^-4时，改进算法下小站信号的解调性能提升了1 dB，说明改进算法优于四次方法。     

采用一维物理光学法的天线罩瞄准误差补偿

针对雷达天线罩瞄准误差的补偿问题，提出了一种适用于各向同性的天线罩瞄准误差修正方法。构建了基于一维物理光学法的天线罩瞄准误差的数学模型，推导了雷达导引头测量目标角度和角速度的误差修正公式。试验结果表明，该方法有效降低了天线罩瞄准误差对目标角速度性能的影响。     

Reduction in thickness error of optical coatings by dividing thick layers and monitoring with multiple witness glasses

We present a monitoring strategy based on using two pieces of witness glass, which are brought to the measuring position in a specially chosen sequence, each witness glass is monitored by one single wavelength. To reduce the thickness error, some thick layers are divided into two layers and monitored by different witness glasses. Theoretical analysis and experimental results have demonstrated that the proposed monitoring strategy can achieve spectral performance close to the theoretical design.