EWT 算法在姿态解算中的应用

针对陀螺仪存在低频噪声和漂移误差导致姿态测量精度下降的问题,提出采用经验小波变换( empirical wavelet transform,EWT)算法融合陀螺仪、加速度计解算姿态角。 首先运用 EWT 算法对陀螺仪采集的数据进行频谱分割,得到信号的 模态分量;其次采用小波自适应软阈值去噪的方法对信号进行降噪处理并重构信号,得到处理后的陀螺仪数据;然后根据 PID 互补滤波方法,利用加速度计的数据实现对陀螺仪数据的修正;最后利用校正后的陀螺仪数据,结合龙格库塔法解算四元数,从 而通过四元数获得精确的姿态角。 实验结果表明,EWT 算法融合陀螺仪和加速度计,能够将姿态解算精度提高 50%,且降噪效 果良好,满足姿态解算准确性的要求。     

Influence of bearing damping on instability of asymmetric shafts-Part I. Stabilizing and destabilizing effects

This paper investigates the influence of bearing damping on the instability of rotating asymmetric shafts supported by isotropic bearings. In the rotating frame of reference, an analytical method based on modal expansion is developed to determine transition curves for stable and unstable regions. The effects of damping coefficients of bearings on the dynamic instability are evaluated for various bearing stiffness.     

片盘车场设计方法

片盘车场是井工矿区必不可少的车场形式。本文主要针对车场的主要设计形式 ,各种形式的优缺点 ,并提供了斜面回转时平、竖曲线的准确计算方法。     

弯道声光预警信号装置的应用

煤矿井下轨道运输大巷的弯道是设备、物料进出和安全运输的咽喉要道,车辆运行频繁、运量大,车辆交汇易造成事故,如果安装弯道声光预警信号装置就可以保证大巷运输的安全。     

煤炭燃点测定仪的设计与实现

针对市场上煤炭燃点测定仪测量精度低,试验过程可视化效果不好等缺陷,设计了一种新型煤炭燃点测定仪。系统利用ModBus传输协议和CRC16位校验技术实现了上位机与下位机的通信。上位机采用温度数字过滤程序,同时结合下位机采用冒泡排序法,滤除了温度突变值,解决了温度探头可能有较大突变而带来的误差问题,保证了燃点测定的精确可靠,本系统界面设计友好,可视化效果佳且操作更为方便。     

600MW机组凝汽器最佳经济方案选择及特性曲线分析

在提高机组初参数条件受到一定限制的情况下,从设计、制造和运行环节如何保证凝汽器的安全运行来提高汽轮发电机组的经济性得到各方面的重视.在上述背景下,国内外竞相开展了凝汽器的最佳经济方案的研制工作.以某厂600MW汽轮机组为例,根据汽轮机的设计参数,选择不同的冷却倍率,冷却水流速以及流程数,从经济角度确定凝汽器的最佳运行方案,计算得出冷却倍率为70的双流程凝汽器为最佳设计方案.此外,还利用Matlab编程绘制了该凝汽器在不同冷却水量及不同冷却水进口温度下的特性曲线,并对几个典型工况曲线进行了分析,为凝汽器的运行,改造提供参考依据.     

Modeling the Growth Rate of Listeria Monocytogenes Using Absorbance Measurements and Calibration Curves

ABSTRACT:  The influence of environmental conditions (temperature and pH) on the relationship between growth data expressed by absorbance (ABS) and data transformed to cell count (CC) measurements was studied, using calibration curves for predicting Listeria monocytogenes growth rate. With this aim, 19 calibration curves at different stress conditions were performed. A shift in the calibration curves was observed for the most stringent conditions, which affected cell viability. Subsequently, a Baranyi model was fitted to ABS and CC data to obtain growth rate (GR_ABS and GR_CC) and a linear regression was performed. Absorbance was found to be a reliable technique for measuring microbial growth, as a strong relationship between GR_ABS and GR_CC (R²= 0.9717) was observed. Furthermore, 2 different response surface models were developed to link GR_ABS and GR_CC data with temperature, citric acid, and ascorbic acid. The goodness of fit of both ABS and CC models to the data was observed (RMSE = 0.0223 and 0.0221; SEP [%]= 29 and 25, respectively). Mathematical validation was carried out by calculating bias and accuracy factors, providing reasonably acceptable values for both absorbance and cell count models (B_f= 1.11 and 1.09, A_f= 1.44 and 1.41, respectively). Predictions for GR_CC were compared to data taken from Growth Predictor software at different temperatures and pH. Response surface model predictions showed that a suitable combination of preservative factors can inhibit L. monocytogenes growth. These results highlight accurate predictions of growth parameters of L. monocytogenes .     

A review: Energy recovery in batch processes

The implementation of batch processing has increased due to its intrinsic flexibility and adaptability. These are essential characteristics when it comes to producing high-value added materials such as agrochemicals, pharmaceuticals, specialty chemicals…the demand for which has grown in recent decades.Although industrial processes are highly diverse, a common feature to all is that they utilize fossil fuels as the energy source. The reliance on fossil fuels as a primary source of energy generates a negative impact on the environment. The implantation of renewable energies and efficient usage of energy has thus become crucial. Improving energy use could be achieved through advancements in plant machinery and the use of methodologies such as ‘process integration’.Process integration can be described as system oriented methods that could be used during the design and retrofit of industrial processes in order to obtain an optimal utilization of resources. The methods have traditionally focused on an efficient energy use, although recently process integration techniques cover other areas such as efficient use of raw materials, emission reduction and process operations. Energy integration tries to reach the optimization of heat, power, fuel and utilities.The consideration of energy integration complicates the process design and the generation of batch process design alternatives, so what is now required is the proposal and development of different approaches and methods oriented towards recovering energy in this kind of industrial process. Improving energy end-use efficiency will make it possible to reduce dependence on energy imports and bring about innovation and competitiveness.The aim of this work is report the main contributions that have been carried out in order to attain energy integration in batch processes, as well as different examples of applications that have shown the possibilities offered by the developed tools.     

Improving inter-plant integration of syngas production technologies by the recycling of CO2 and by-product of the Fischer-Tropsch process

This paper deals with the emission reduction in synthesis-gas production by better integration and increasing the energy efficiency of a high-temperature co-electrolysis unit combined with the Fischer-Tropsch process. The investigated process utilises the by-product of Fischer-Tropsch, as an energy source and carbon dioxide as a feedstock for synthesis gas production. The proposed approach is based on adjusting process streams temperatures with the further synthesis of a new heat exchangers network and optimisation of the utility system. The potential of secondary energy resources was determined using plus/minus principles and simulation of a high-temperature co-electrolysis unit. The proposed technique maximises the economic and environmental benefits of inter-unit integration. Two scenarios were considered for sharing the high-temperature co-electrolysis and the Fischer-Tropsch process. In the first scenario, by-products from the Fischer-Tropsch process were used as fuel for a high-temperature co-electrolysis. Optimisation of secondary energy sources and the synthesis of a new heat exchanger network reduce fuel consumption by 47% and electricity by 11%. An additional environmental benefit is reflected in emission reduction by 25,145 tCO₂/y. The second scenario uses fossil fuel as a primary energy source. The new exchanger network for the high-temperature co-electrolysis was built for different energy sources. The use of natural gas resulted in total annual costs of the heat exchanger network to 1,388,034 USD/y, which is 1%, 14%, 116% less than for coal, fuel oil and LPG, respectively. The use of natural gas as a fuel has the lowest carbon footprint of 7288 tCO₂/y. On the other hand, coal as an energy source has commensurable economic indicators that produce 2 times more CO₂, which can be used as a feedstock for a high-temperature co-electrolysis. This work shows how in-depth preliminary analysis can optimise the use of primary and secondary energy resources during inter-plant integration.     

计算Weil/Tate配对的快速算法

对文献中的计算Weil/Tate配对的方法进行了分析,并在其基础上进行了改进,提出了2个计算Weil/Tate配对的快速算法.分析表明,改进后算法的效率均有明显提高.2种改进方法具有运算量低,且易于实现的功能.通过实例验证了2种改进算法.