宝珠寺水电站设计效益与运行效益差异分析

四川省宝珠寺水电站自1997年建成运行以来，年平均发电量只有12亿kW-h左右，不足设计发电量（22亿kW-h）的60％，所发电量严重不足。其实际发电量与设计发电量差距较大的原因主要在于：所用水库径流系列的差异、水电站设计调度图的水位设置与实际运行情况有出入、电力系统市场需求以及对水库运行方式的约束等。为此，推荐了新的水电站调度图，并在此基础上计算了多年平均发电量。分析结果对其他水电站类似问题的解决具有参考价值。     

MIMO Frequency Hopping Spread Spectrum Multi-Carrier Multiple Access: A Novel Uplink System for B3G Cellular Networks

In this paper, we propose and give the performance of a novel uplink system based on the combination of multi-carrier (MC), code division multiple access (CDMA) and multiple input multiple output (MIMO) techniques. First, we describe the interests of spread-spectrum multi-carrier multiple access (SS-MC-MA) scheme for uplink, especially compared to MC-CDMA. Classically, with SS-MC-MA, each user spreads its data symbols on a specific subset of adjacent or multiplexed subcarriers, to facilitate the channel estimation and reduce complexity at the reception. In order to compensate for the lack of frequency diversity of SS-MC-MA with adjacent subcarriers, we first combine it with an orthogonal space-time block code (STBC) and demonstrate the resulting spatial diversity gain. Then, we propose to allocate the subsets to the different users by applying a frequency hopping pattern (FH). In that case, each user benefits from the frequency diversity linked to the total bandwidth as with the multiplexed subcarriers solution, while keeping the advantages of the adjacent subcarriers solution. The gain provided by the use of the frequency hopping is stressed on. Finally, the performance of this scheme is evaluated over realistic MIMO channel with channel turbo coding for systems offering asymptotic spectrum efficiency of 1, 2, 3 and 4.5 bit/s/Hz. Thus, the efficiency of the novel proposed STBC FH SS-MC-MA system as a very promising multiple access and modulation scheme for the uplink of the future wideband wireless networks is successfully demonstrated.     

Effects of grade control structures on the macroinvertebrate assemblage of an agriculturally impacted stream

Nearly 400 rock rip‐rap grade control structures (hereafter GCS) were recently placed in streams of western Iowa, USA to reduce streambank erosion and protect bridge infrastructure and farmland. In this region, streams are characterized by channelized reaches, highly incised banks and silt and sand substrates that normally support low macroinvertebrate abundance and diversity. Therefore, GCS composed of rip‐rap provide the majority of coarse substrate habitat for benthic macroinvertebrates in these streams. We sampled 20 sites on Walnut Creek, Montgomery County, Iowa to quantify macroinvertebrate assemblage characteristics (1) on GCS rip‐rap and at sites located (2) 5–50 m upstream of GCS, (3) 5–50 m downstream of GCS and (4) at least 1 km from any GCS (five sites each). Macroinvertebrate biomass, numerical densities and diversity were greatest at sites with coarse substrates, including GCS sites and one natural riffle site and relatively low at remaining sites with soft substrates. Densities of macroinvertebrates in the orders Ephemeroptera, Trichoptera, Diptera, Coleoptera and Acariformes were abundant on GCS rip‐rap. Increases in macroinvertebrate biomass, density and diversity at GCS may improve local efficiency of breakdown of organic matter and nutrient and energy flow, and provide enhanced food resources for aquatic vertebrates. However, lack of positive macroinvertebrate responses immediately upstream and downstream of GCS suggest that positive effects might be restricted to the small areas of streambed covered by GCS. Improved understanding of GCS effects at both local and ecosystem scales is essential for stream management when these structures are present. Copyright © 2007 John Wiley & Sons, Ltd.     

论通信动力系统运维效益的量化方法

为了实现通信动力系统运维管理部门的量化考核与绩效改进,文章提出了基于成本与网络风险损失的动力运维效益量化方法,直接计算单位成本的有效电度,并提供网络风险损失系数取值的建议。     

Numerical simulation of the solar chimney power plant systems coupled with turbine

Numerical simulations have been carried out on the solar chimney power plant systems coupled with turbine. The whole system has been divided into three regions: the collector, the chimney and the turbine, and the mathematical models of heat transfer and flow have been set up for these regions. Using the Spanish prototype as a practical example, numerical simulation results for the prototype with a 3-blade turbine show that the maximum power output of the system is a little higher than 50 kW. Furthermore, the effect of the turbine rotational speed on the chimney outlet parameters has been analyzed which shows the validity of the numerical method advanced by the author. Thereafter, design and simulation of a MW-graded solar chimney power plant system with a 5-blade turbine have been presented, and the numerical simulation results show that the power output and turbine efficiency are 10 MW and 50%, respectively, which presents a reference to the design of large-scale solar chimney power plant systems.     

综放仰斜开采顶板初跨规律及围巷稳定性研究

通过进行综放工作面仰斜开采顶板初跨规律及围巷稳定性研究,可合理指导回采工作面在初采老顶跨落期间的顶板管理以及合理确定风运两巷超前支护参数、排水巷与切眼间煤柱,为首采工作面围岩结构分析提供了新的思路和方法。     

Output power leveling of wind turbine generators using pitch angle control for all operating regions in wind farm

Effective utilization of renewable energies such as wind energy instead of fossil fuels is desirable. Wind energy is not constant and windmill output is proportional to the cube of the wind speed, which causes the generated power of wind turbine generators (WTGs) to fluctuate. In order to reduce the output power fluctuation of wind farms, this paper presents an output power leveling control strategy for a wind farm based on both the average wind farm output power and the standard deviation of the wind farm output power, a cooperative control strategy for WTGs, and pitch angle control using a generalized predictive controller (GPC) in all WTG operating regions. Simulation results using an actual detailed model for wind farm systems show the effectiveness of the proposed method. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 158(4): 31– 41, 2007; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20448     

泡沫沥青稳定技术在新西兰的应用

介绍了泡沫沥青稳定技术在我国沥青路面冷再生中的一些应用情况。为了推动这项技术的快速发展，重点介绍新西兰泡沫沥青混合料配合比的设计方法及混合料的力学特性。主要包括比较两种油源各两种标号的沥青的发泡特性，提出了泡沫沥青的技术指标。采用常用的矿料级配配制泡沫沥青混合料，研究了混合料的设计方法（包括最佳含水量及泡沫沥青含量的确定），比较了3种室内压实方法对混合料密度的影响。同时，分析了水泥对泡沫沥青混合料不同龄期强度的影响，并推荐了泡沫沥青冷再生路面的开放交通时间。     

Case Study: Channel Stability of the Missouri River, Eastern Montana

The construction of Fort Peck Dam in the 1930s on the Missouri River, eastern Montana, initiated a series of changes in hydrologic conditions and channel morphology downstream from the dam that impacted channel stability. Impacts included streambed degradation of up to 3.6 m and substantially altered magnitude, frequency, and temporal distribution of flows. To investigate the effects of the altered flow regime and bed degradation on bank stability, two independent bank-stability analyses (one for planar failures, the other for rotational failures) were performed on 17 outside meanders. Both included the effects of matric suction and positive pore-water pressures, confining pressures, and layering. Instability occurred from the loss of matric suction and the generation of positive pore-water pressures. In this semiarid region, such hydrologic conditions are most likely to occur from the maintenance of moderate and high flows (greater than 425–566 m3/s) for extended periods (5–10 days or more), thereby providing a mechanism for saturation of the streambank. For the postdam period, average annual frequencies of flows maintained above 566 m3/s for 5- and 10-day durations are 149 and 257% greater, respectively. The analyses indicated that 30% of the sites were susceptible to planar failures while 53% of the sites were susceptible to rotational failures under sustained moderate- and high-flow conditions, while under a worst-case rapid drawdown scenario, 80% of the banks were susceptible to failure. Despite the negative effects of the altered flow regime, analysis of maps and aerial photographs shows that closure of Fort Peck Dam has resulted in a fourfold reduction of the average rate of long-term channel migration between the dam and the North Dakota border.     

A novel artificial bee colony detection algorithm for massive MIMO system

As a hot‐spot of 5G, the research on detection algorithms for massive multiple input multiple output (MIMO) system is significant but difficult. The traditional MIMO detection algorithms or their improvements are not appropriate for large scaled antennas. In this paper, we propose artificial bee colony (ABC) detection algorithm for massive MIMO system. As one advanced technology of swarm intelligence, ABC algorithm is most efficient for large scaled constrained numerical combinatorial optimization problem. Therefore, we employ it to search the optimum solution vector in the modulation alphabet with linear detection result as initial. Simulation and data analysis prove the correctness and efficiency. Versus the scale of massive MIMO systems from 64 × 64 to 1024 × 1024 with uncoded four‐quadrature‐amplitude‐modulation signals, the proposed ABC detection algorithm obtains bit error rate of 10 ^− 5 at low average received signal‐to‐noise‐ratio of 12 dB with rapid convergence rate, which approximates the optimum bit error rate performance of the maximum likelihood and achieves the theoretical optimum spectral efficiency with low required average received signal‐to‐noise‐ratio of 10 dB in similar increasing regularity, over finite time of low polynomial computational complexity of per symbol, where N_T denotes the transmitting antennas' number. The proposed ABC detection algorithm is efficient for massive MIMO system. Copyright © 2016 John Wiley & Sons, Ltd.