The keyboard blues: Modern technology and the rights and risks of people at work

Health and safety at work is a moral imperative, but the debates emphasise only the economic and legal sides. Drawing on case material from working with VDUs and other forms of modern technology it is shown that loss of control over their immediate work processes can be stressful and potentially harmful to responsible operators. Autonomy and freedom in work process control enhances the power that workers have to protect their health. It is suggested that unquestioned divisive and dualistic practices at workplaces are a potent and unnecessary reason for this problem.A human being can only survive in the Age of Machinery if the ethical norms of life are held sacred. This Shamanist protest at the destructive power of evil, as expressed in theCurse Upon Iron, stands forth prominently in a society in moral crisis.     

President’s column.

Presents remarks from the president of the APA's Division 13 (Division of Consulting Psychology). The author discusses the second annual Colorado conference on consulting to corporations and business; the planning for Division activities at the APA convention in Los Angeles; and the affect of health reform on consulting psychology and consulting psychologists. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Novel Technique for Channel Estimation and Equalization for High Mobility OFDM Systems

Orthogonal frequency division multiplexing (OFDM) technique, when used in wireless environments, is known to be robust against frequency selective fading. However, when the channel shows time selective fading, rapid variations destroy the subcarrier orthogonality and introduce inter-carrier interference (ICI). The use of ICI mitigation schemes requires the availability of channel state information (CSI) at the receiver, which is a non-trivial task in fast fading systems. In our work, we have addressed the problem of estimation of rapidly varying channels for OFDM systems. The channel is modeled using complex exponentials as basis functions and the estimation process makes use of the cyclic prefix (CP) part available in OFDM symbols as training. The system is viewed as a state space model and Kalman filter is employed to estimate the channel. Following this, a time domain ICI mitigation filter that maximizes the received SINR (signal to interference plus noise ratio) is employed for equalization. This method performs considerably well in terms of MSE as well as BER at very high Doppler spreads.

Adaptive resource allocation techniques in OFDMA using cross-layer architecture

This paper utilizes the cross-layer architecture to implement adaptive resource allocation in Orthogonal Frequency Division Multiple Access （OFDMA） based on the broadband wireless access system. According to the cross-layer architecture, the information in link layer is used for adaptive resource allocation in OFMDA. A new cross-layer adaptive resource allocation algorithm is developed which can guarantee the users to be in minimum average waiting time in link-layer and get the better spectrum utilization. Numerical results show that our scheme is appealing and can get about half of average waiting time less and 0.5 bps/Hz spectrum utilization more than the scheme in 1EEE802.16a.     

Performance analysis and simulation of OCDMA system based on FBGs encoder/decoder

The encoding/decoding scheme based on Fiber Bragg Grating （FBG） for Optical Code Division Multiple Access （OCDMA） system is analyzed and the whole process from transmitting end to receiving end is researched in detail. The mathematical mode including signal transmission, summing, receiving and recovering are established respectively. One of the main sources of Bit Error Rate （BER） of OCDMA system based on FBGs is the unevenness of signal power spectrum, which leads to the chip powers unequal with each other. The Signal to Interfere Ratio （SIR） and BER performance of the system are studied and simulated at the case with uneven distribution of chips＇ powers.     

A novel estimation method of timing offset for OFDM based WLAN systems

The conventional timing synchronization methods based on time domain correlation have the problems of timing metric plateau in Additive White Gaussian Noise(AWGN) channel and estimation error in multipath fading channel. To resolve the problems, this paper proposes a novel timing metric using the characteristics of long training symbols in IEEE802.11a and a new timing recovery method based on the new timing metric for Orthogonal Frequency Division Multiplexing(OFDM)-based WLAN systems. The proposed timing metric is defined as a sum of absolute values of the imaginary parts of all the subcarrier samples. It exhibits a unique characteristic that is very sensitive to the true synchronization point since it has minimum value at the true synchronization point and maximum around the true synchronization point. The simulation results show that the performance of timing synchronization is significantly improved, as a result, the probability of error estimation is lower than 10^-4 when Signal-to-Noise Ratio(SNR) is more than 10dB.     

新的基于粒子群优化的正交频分复用系统盲频偏估计算法

针对正交频分复用(OFDM)系统频偏估计问题,提出了一种基于粒子群优化(PSO)的盲频偏估计算法。首先,根据频偏估值重建的接收信号和实际接收到的信号误差最小原则构造了盲频偏估计的数学模型,并推导出了代价函数;然后,利用粒子群优化算法强大的随机并行全局搜索能力,通过最小化代价函数估计频偏。仿真比较了常系数、微分递减两种惯性权重策略PSO算法的频偏估计性能,并与最小输出方差、黄金分割盲频偏估计算法进行了比较分析。仿真结果表明,所提算法精度高,同一信噪比下较同类算法大约有一个数量级的提升,且不受调制类型和频偏估计范围(-0.5,0.5)的限制。     

基于802.16e的OFDM调制解调技术的研究

随着正交频分复用技术（OFDM）的日益成熟,它在现实生活中的应用的范围也越来越广泛了。OFDM技术现在不仅广泛的应用在数字广播、数字电视中,而且由于其具有抗多径衰落,频谱利用率高,传输速度快的优点,被普偏认为是第四代移动通信物理层的关键技术之一,它能够同时为多个用户提供高数据速率的视频和语音服务。主要是针对基于802.16e标准的OFDM的不同调制解调方式在不同信道中传输的优缺点进行研究比较。     

802.1 I p Physical Layer the OFDM Baseband Modulator FPGA Implementation

基于IEEE802．11p标准的车辆无线通信系统作为智能交通系统的一部分,能极大地改善交通系统的安全性、有效性和实时性。该文详细描述了作者对车辆无线通讯系统关键技术进行的相关研究内容,并且在cyclnneⅢEP3C120F平台上实现了一种基于IEEE802．11p标准的物理层OFDM基带调制系统,效果理想,有很好的移植性。     

河南省安阳市第四系的初步划分

通过对安阳市第四系各类钻孔的搜集,基本查明了第四系在区内的分布、规模、特征、成因;该区的第四系堆积物,除分布于丘陵地区外,还广布于区内东半部的冲积平原,其岩性岩相变化大,厚度由西向东逐渐变厚,层次由多层到单层,颗粒逐渐变细,成因由冲洪积→冲积→坡冲积的变化规律,同时也反映了由老到新,坡冲积堆积范围由大到小,冲积范围由小到大的演变过程。