Multi-state techno-economic model for optimal dispatch of grid connected hydrogen electrolysis systems operating under dynamic conditions

The production of hydrogen through water electrolysis is a promising pathway to decarbonize the energy sector. This paper presents a techno-economic model of electrolysis plants based on multiple states of operation: production, hot standby and idle. The model enables the calculation of the optimal hourly dispatch of electrolyzers to produce hydrogen for different end uses. This model has been tested with real data from an existing installation and compared with a simpler electrolyzer model that is based on two states. The results indicate that an operational strategy that considers the multi-state model leads to a decrease in final hydrogen production costs. These reduced costs will benefit businesses, especially while electrolysis plants grow in size to accommodate further increases in demand.     

Economic viability assessment of sustainable hydrogen production,storage, and utilisation technologies integrated into on- and off-grid micro-grids: A performance comparison of different meta-heuristics

In recent years, there has been considerable interest in the development of zero-emissions, sustainable energy systems utilising the potential of hydrogen energy technologies. However, the improper long-term economic assessment of costs and consequences of such hydrogen-based renewable energy systems has hindered the transition to the so-called hydrogen economy in many cases. One of the main reasons for this is the inefficiency of the optimization techniques employed to estimate the whole-life costs of such systems. Owing to the highly nonlinear and non-convex nature of the life-cycle cost optimization problems of sustainable energy systems using hydrogen as an energy carrier, meta-heuristic optimization techniques must be utilised to solve them. To this end, using a specifically developed artificial intelligence-based micro-grid capacity planning method, this paper examines the performances of twenty meta-heuristics in solving the optimal design problems of three conceptualised hydrogen-based micro-grids, as test-case systems. Accordingly, the obtained numeric simulation results using MATLAB indicate that some of the newly introduced meta-heuristics can play a key role in facilitating the successful, cost-effective development and implementation of hydrogen supply chain models. Notably, the moth-flame optimization algorithm is found capable of reducing the life-cycle costs of micro-grids by up to 6.5% as compared to the dragonfly algorithm.     

东江源区地表水环境质量变化趋势分析与对策

根据江西省赣州市水环境监测中心的实测资料分析,运用季节性肯达尔检验方法,分析了东江源区地表水环境变化趋势,提出相应的解决对策.     

某工业园周边农田土壤重金属污染特征及潜在风险评价

为探究某工业园周边农田土壤重金属污染及潜在风险状况,系统采集了园区周边农田15个表层土壤,通过测定土壤的pH及重金属Pb、Cu、Zn、Cd、Cr、Ni,并借助Pearson相关性分析和主成分分析等分析方法,及内梅罗指数法及Hakanson潜在风险评价指数法等评价方法,进一步揭示重金属的污染特征及潜在风险。研究结果表明：Pb、Cu、Zn和Cd的平均含量超过了我国农用地风险筛选值,Cd的平均含量甚至超过管制值,该地区土壤已不适合作为农用地用途;距离工业区较近的土壤中重金属浓度较高,研究区土壤中重金属污染来源与工业园关系密切;内梅罗综合指数污染法评价表明所有采样点的土壤均为重度污染,各金属元素的潜在风险指数从大到小依次为Cd＞Pb＞Cu＞Ni＞Cr＞Zn,其中Cd是对潜在生态风险指数贡献最大的金属元素。人体健康风险评估表明,Pb、V和As对人体造成非致癌风险的很显著,As存在很大可能的致癌风险。周边工矿活动等人为活动对土壤的重金属贡献份额达71.99%,自然源贡献为17.06%。整体来看,研究区土壤呈现极高生态风险水平,应当对该区域土壤污染采取一定的调控措施。     

Alkanes,Terpanes, and Aromatic Hydrocarbons in Surficial Sediments of Halifax Harbor

Hydrocarbons were quantified in surficial sediments of Halifax Harbor. Alkanes ranging from nC-15 to nC-33 were detected in all samples at a mean concentration of 23.2 - 12.3 w g/g, dry. A lower mean concentration of 7.0 - 3.3 w g/g, dry, was observed for the smaller nC-15 to nC-22 alkanes, which represented between 15% and 60% of summed alkanes. The site with the highest sum of alkanes (46.4 w g/g, dry) also had the highest carbon preference index for the nC-15 to nC-33 alkanes (1.41), and lowest ratios of C-17 to pristane (1.23) and C-18 to phytane (0.83), reflecting terrestrial inputs, both biogenic and petrogenic. The latter source was confirmed by the profile of terpanes, including the hopanes. The ratio of tricyclic to summed terpanes remained relatively constant at all sites 0.26 - 0.04, revealing a chronic petrogenic input, with a moderate degree of degradation, because they were present in a concentration range (i.e., 15.0 - 10.0 w g/g) similar to that of alkanes. A site adjacent to a sewage treatment plant displayed lower levels of alkanes, terpanes, and unresolved complex mixture as well as PACs compared to the two closest sites. Two sites at the entrance to the harbor consistently displayed lower levels of all hydrocarbons.     

Generalized Trapezoidal Formulas For The Symmetric Heat Equation In Polar Coordinates II. The Case Of Point Sources

The present paper is in continuation of our previous paper Chawla et al. [4]. An important class of applications of the radially symmetric heat equation in polar coordinates: u_{t}=v ( u_{rr}\,+\; ( a/r ) u_{r} ), involve the presence of a continuous point source of heat at the centre of the sphere ( a=2 ) or on the axis of the cylinder ( a=1 ). This necessitates a modification of the radial grid used in [4]; our modification of the radial grid in the present paper accommodates a point source of heat at r=0 in a natural way. We then extend generalized trapezoidal formulas GTF( \alpha ) for the one-step time integration of these problems. Again, with the help of the generalized finite Hankel transforms introduced in [4] we are able to obtain, in a natural way, analytical solutions of the heat equation in the presence of point sources of heat for both the cases a=1 and a=2 . Numerical experiments are provided to compare the performance of the GTF( \alpha ) time integration scheme with the schemes based on the backward Euler and the classical arithmetic-mean trapezoidal formula.     

关于东江源区水资源保护与治理的几点思考

介绍珠江三角洲和香港地区的主要饮水水源——东江源的水资源现状,针对目前该区水资源的保护存在的一些问题提出建议.     

A modified particle swarm optimization algorithm for scheduling renewable generation in a micro-grid under load uncertainty

Renewable Energy Sources (RESs) have many benefits especially when integrated in micro-grids. In this paper, the particle swarm optimization (PSO) algorithm is modified for the optimal power sharing among several RESs such as wind (WT), photovoltaic (PV), and a combined heat and power (CHP) plants within a micro-grid framework. To evaluate the proposed method, first it is utilized to optimally schedule RESs in a micro-grid with the aim of cost minimization without uncertainty. Then, it is implemented under the load uncertainty and the random nature of demand is modeled by the scenario-based stochastic programming. Finally, the proposed algorithm is verified using some benchmark functions. The proposed method is compared with some different Meta-heuristic algorithms and it presents encouraging results in the RESs scheduling and solving benchmark functions.     

信息准则在信息融合中的应用

在图像识别时,如果样本较小,往往会造成识别结果的不准确.采用信息融合的方法可以改善这一问题.在这一过程中,通过引入信任度系数对信息源的质量作出评价,可以提高图像识别的准确性.提出了一种利用信息准则来确定信息源信任度系数的方法,并以此作为衡量信息源质量的依据.其中着重比较了根据两种不同的信息准则所确定的信任度系数对于识别结果的影响.实验结果表明利用BIC准则确定的信任度系数可以得到更好的图像识别结果,同时也证明了该方法应用在信息融合中的可行性.     

Mining spatio-temporal patterns in object mobility databases

With the increasing use of wireless communication devices and the ability to track people and objects cheaply and easily, the amount of spatio-temporal data is growing substantially. Many of these applications cannot easily locate the exact position of objects, but they can determine the region in which each object is contained. Furthermore, the regions are fixed and may vary greatly in size. Examples include mobile/cell phone networks, RFID tag readers and satellite tracking. This demands techniques to mine such data. These techniques must also correct for the bias produced by different sized regions. We provide a comprehensive definition of Spatio-Temporal Association Rules (STARs) that describe how objects move between regions over time. We also present other patterns that are useful for mobility data; stationary regions and high traffic regions. The latter consists of sources, sinks and thoroughfares. These patterns describe important temporal characteristics of regions and we show that they can be considered as special STARs. We define spatial support to effectively deal with the problem of different sized regions. We provide an efficient algorithm—STAR-Miner—to find these patterns by exploiting several pruning properties. Responsible editors: Charles Perng and Tao Li.