Optimization of molten carbonate fuel cell (MCFC) and homogeneous charge compression ignition (HCCI) engine hybrid system for distributed power generation

In a previous study, a new hybrid system of molten carbonate fuel cell (MCFC) and homogeneous charge compression ignition (HCCI) engine was developed, where the HCCI engine replaces the catalytic burner and produces additional power by using the left-over heating values from the fuel cell stack. In the present study, to reduce the additional cost and footprint of the engine system in a hybrid configuration, the possibility of engine downsizing is investigated by using two strategies, i.e. the use of a turbocharger and the use of high geometric compression ratio for the engine design, both of which are to increase the density of the intake charge and thus the volumetric efficiency of the engine. Combining these two strategies, we suggest a new engine design with ∼60% of displacement volume of the original engine. In addition, operating strategies are developed to run the new hybrid system under part load conditions. It is successfully demonstrated that the system can operate down to 65% of the power level of the design point, while the system efficiency remains almost unchanged near 63%.     

Augmented reality in informal learning environments: A field experiment in a mathematics exhibition

Recent advances in mobile technologies (esp., smartphones and tablets with built-in cameras, GPS and Internet access) made augmented reality (AR) applications available for the broad public. While many researchers have examined the affordances and constraints of AR for teaching and learning, quantitative evidence for its effectiveness is still scarce. To contribute to filling this research gap, we designed and conducted a pretest–posttest crossover field experiment with 101 participants at a mathematics exhibition to measure the effect of AR on acquiring and retaining mathematical knowledge in an informal learning environment. We hypothesized that visitors acquire more knowledge from augmented exhibits than from exhibits without AR. The theoretical rationale for our hypothesis is that AR allows for the efficient and effective implementation of a subset of the design principles defined in the cognitive theory of multimedia learning. The empirical results we obtained show that museum visitors performed significantly better on knowledge acquisition and retention tests related to augmented exhibits than to non-augmented exhibits and that they perceived AR as a valuable and desirable add-on for museum exhibitions.     

Operation Assist by Vibration Suppression Control Using Impulse‐Shaped Signals for Power Assist Conveyance System

This paper presents an assist control method for a flexible parts conveyance task using a power assist conveyance system. The assist control method should be designed so as not only to suppress vibration but also to reduce the degradation of operating feel. For this purpose, multiple impulse‐shaped signals are used as feedforward signals in order to reduce the vibration of flexible parts during conveyance. In addition, the adjustment time is introduced to adjust the input timing of the impulse‐shaped signal and to suppress vibration. In order to improve the degradation of operating feel, the smaller amplitudes of the three impulse‐shaped signals are used and input repeatedly. The effectiveness of the proposed system was verified experimentally. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(2): 31–39, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22476     

Applying the kriging method to predicting irradiance variability at a potential PV power plant

One-second irradiance data from forty-five sensors spaced over a one-mile square section of land were analyzed to characterize the short-term (1-s to 1-min) variability of the solar resource in Northern Arizona. The geostatistical interpolation model known as kriging was applied to our data set to better understand the method's strengths and weaknesses in accurately predicting the variations in the irradiance over this relatively small section of land. Of particular interest was to investigate the ability of the kriging method to show the variation in solar irradiance over the section of land as compared to that measured by the sensors. When using data from all the sensors as input to the prediction method, kriging performed very well compared to the sensors. However, because it is unlikely to have a large number of sensors to characterize the variability at a prospective solar site, it was also of interest to investigate how many sensors are required as input to the kriging technique in order to generate a reliable prediction. Solar data from four characteristic periods (related to the four seasons) were analyzed, and different sensor configurations, consisting of subsets of the actual sensor array, were employed using the method to demonstrate the number of sensors required to correctly characterize the short-term irradiance variability at the site. Using four measurement stations as input to the kriging method was shown to reasonably represent the variability in the 1-s to 1-min timescales.     

高炉水渣排汽筒在线更换改造技术

为根本解决宝钢股份炼铁厂一号、二号高炉水渣排汽筒筒体腐蚀破损问题,对4根水渣排气筒进行了更新改选,针对工程中,FRP玻璃钢管安装难度大,采取了多种辅助安装措施,确保了工程改选的顺利进行。     

State variable analysis of hydrological systems

The concepts of state and state variables are introduced. From a mathematical point of view the concept of state variables provides the means of transforming a differential equation of any order into an equivalent set of first-order equations. From a physical point of view the state of a system, specified by numeric values of the system state variables at a given time, contains all the relevant information about the system necessary to predict the behaviour of the system in the future. The state variable concept is thus very much suited for analysis of dynamic systems. Examples of the state variable concept applied to analysis of discharge from a reservoir and from two reservoirs operating in series are presented.     

Study on performance and flow field of an undershot cross-flow water turbine comprising different number of blades

Recently,small hydroelectric generators have gained attention as a further development in water turbine technology for ultra low head drops in open channels.The authors have evaluated the application of cross-flow water turbines in open channels as an undershot type after removing the casings and guide vanes to substantially simplify these water turbines.However,because undershot cross-flow water turbines are designed on the basis of cross-flow water turbine runners used in typical pipelines,it remains unclear whether the number of blades has an effect on the performance or flow fields.Thus,in this research,experiments and numerical analyses are employed to study the performance and flow fields of undershot cross-flow water turbines with varying number of blades.The findings show that the turbine output and torque are lower,the fluctuation is significantly higher,and the turbine efficiency is higher for runners with 8 blades as opposed to those with 24 blades.     

Parallel Operation of Centrifugal Pumps: Effects of Rotational Speed Differences due to Motor Slip

In industrial plants, centrifugal pumps are frequently operated in parallel configuration, not least for redundancy and operational reliability reasons. However, regarding the resulting pressure pulsations and energy consumption, this operation mode has so far not been in the focus of scientific studies. The object of the present article is to clarify the effect of parallel operation with respect to the observable pressure pulsations. Measurements were carried out with two identical centrifugal pumps operating in parallel mode in an industrial‐scale closed‐loop piping system. The results suggest that, regarding both the resulting pressure pulsations and the operating point of each pump, this operation mode is quite sensitive to smallest rotational speed deviations as they may occur due to different motor slip. The results indicate furthermore that, for minimum pressure pulsations, equal power consumptions of the two pumps are crucial, but not necessarily equal rotational speeds.     

集中供暖换热站扩容供热方式的选择

通过对某换热站新增区域的供热方式与原采暖用户进行系统分析,建议新增区采用间接连接和混水直接连接两种方案,并对两种方案给出详细的设计说明;通过对两种方案进行整体比较分析,综合得出混水直供换热方式运行经济,供热效果良好,尤其是区域供热新增区或新建区采暖用户的供热选择方式。