Data-driven parameterization of polymer electrolyte membrane fuel cell models via simultaneous local linear structured state space identification

In order to mitigate the degradation and prolong the lifetime of polymer electrolyte membrane fuel cells, advanced, model-based control strategies are becoming indispensable. Thereby, the availability of accurate yet computationally efficient fuel cell models is of crucial importance. Associated with this is the need to efficiently parameterize a given model to a concise and cost-effective experimental data set. A challenging task due to the large number of unknown parameters and the resulting complex optimization problem. In this work, a parameterization scheme based on the simultaneous estimation of multiple structured state space models, obtained by analytic linearization of a candidate fuel cell stack model, is proposed. These local linear models have the advantage of high computational efficiency, regaining the desired flexibility required for the typically iterative task of model parameterization. Due to the analytic derivation of the local linear models, the relation to the original parameters of the non-linear model is retained. Furthermore, the local linear models enable a straight-forward parameter significance and identifiability analysis with respect to experimental data. The proposed method is demonstrated using experimental data from a 30 kW commercial polymer electrolyte membrane fuel cell stack.     

Impact of Lake Michigan water level rise on complex bidirectional flow in the Chicago Area Waterway System (CAWS)

In the past decade, continuously rising water levels in Lake Michigan have been threatening lakefront areas, especially in metropolitan regions like the Greater Chicago area. This provides the motivation to analyze the impact that high lake levels have on the Chicago Area Waterway System (CAWS). As the only primary free connection between the CAWS and Lake Michigan, the Calumet Area waterway subsystem plays a key and unique role. In this work, a numerical model covering the Calumet subsystem and having Lake Michigan as a boundary condition, is set up, calibrated, and validated using limited field observations. It is found that the Calumet subsystem has become bidirectional, where both discharge and flow directions are controlled by lake levels. When lake levels are below −0.15 m (-0.5 ft, Chicago City Datum, CCD), the discharge in the Grand Calumet River is around zero, with water flowing along its east branch towards Indiana. When lake levels are above +0.46 m (+1.5 ft, CCD), the flow reverses direction and drains west into Illinois. In 2020, the mean lake-level was at +1.07 m (+3.5 ft, CCD), and the base discharge in the Grand Calumet River was approximately 8.5 m³/s (300 ft³/s). The higher Lake Michigan’s level is, the larger the discharge would be into Illinois. Potential impact of this extra discharge on Lake Michigan Diversion Accounting (LMDA) of the State of Illinois and flood management in the Chicago Sanitary and Ship Canal (CSSC), is analyzed; while the nature of the bidirectional flows is characterized with the intent of shedding light on this complex phenomenon.     

Malaysia’s electricity market structure in transition

The Malaysian electricity industry evolved from a vertically integrated utility into a single-buyer model, which considered a precursor to deregulation and a competitive market. This study considers electricity sector reform in Malaysia and proposes a market structure for the industry. We focus on the single-buyer model and the pool model for the analysis with the recommendation on reform stages required to ensure a smooth and successful market transition. A smooth transition from regulated market into deregulated market will ensure market stability and sustainability of the energy market. It will also provide enough time for the market participants to adapt and transit from regulated to deregulated energy market.     

A new hybrid solar photovoltaic/ phosphoric acid fuel cell and energy storage system; Energy and Exergy performance

Present work investigates the performance of a combined solar photovoltaic (PV) and Pumped-Hydro and Compressed-Air energy storage system to overcome the challenges of using solar energy systems. This energy system, which is one of the newest hybrid systems, is able to generate electricity and store energy. To examine the solar PV performance the climatic conditions of Shiraz (in Iran) and Abu Dhabi (in UAE) are considered. The results revealed that, the required pump work, which must be supplied by PV system, is equal to 2.85 and 2.62 MJ/m³ for isothermal and isentropic processes, respectively. Furthermore, the total system efficiency is equal to 76.5%. In addition, the total exergy destruction of hybrid system for isentropic process is 8.91% less than that isothermal process. In addition, instead of the solar PV system, a phosphoric acid fuel cell is coupled to the storage system and the results are compared with the main system.     

中国罕见病研究的现状与未来

罕见病是人类社会发展的沉重负担,对罕见病进行深入研究具有重要的社会意义和科学价值。中国人口基数巨大,为罕见病研究提供了广阔资源,同时也带来了巨大挑战。既往中国在罕见病领域取得了众多成就,同时也面临着研究力量分散、资源整合缺乏等问题。随着政府部门、学术机构、研究团体及个人对罕见病研究的重视及参与,中国罕见病研究正朝着协作、创新方向发展。未来的中国罕见病研究将从多个方面推进,为中国及世界应对罕见病挑战作出贡献。     

Review of Antiswing Control of Shipboard Cranes

Shipboard cranes are extensively utilized in numerous fields such as cargo transferring and offshore engineering. The control of shipboard cranes, especially the antiswing control of payloads, has attracted much research attention due to their typical underactuation characteristics and complicated dynamics. Through comparisons of the traditional land-fixed cranes, a brief review on modeling and dynamics analysis is presented to illustrate the tremendous challenges and difficulties in controller design for shipboard cranes. A comprehensive review and brief analysis of shipboard crane control strategies are further presented. Some future research directions are also put forward for reference. It is expected that the paper will be useful for improving existing control schemes and generating novel control approaches for shipboard crane systems.      

刘家山排土场滑坡治理措施

刘家山排土场为民采排弃形成，已经出现大规模滑坡。为了保证上下游生产生活设施的安全，依据现场实际情况，结合现场调查，提出了削坡处理的方案。经过治理后，刘家山排土场平稳地渡过了雨季，目前处于稳定状态，达到了治理目的。     

关于运营商局房管理系统新增功能的浅析

本文对运营商局房资源管理现状进行了分析,阐述了资源管理系统增加审批模块及资源更新的方案,实现工作流程的有效监督。     

大倾角工作面防刮板输送机上窜下滑研究与实践

本文以北辛窑煤矿8103工作面为背景,对刮板输送机“上窜下滑”的机理进行了研究,计算和改进头巷超前推采距离,对“上窜下滑”的防控进行了实践。     

Compiler compatible 5.66 Mb/mm2 8T 1R1W register file in 14 nm FinFET technology

1-read/1-write (1R1W) register file (RF) is a popular memory configuration in modern feature rich SoCs requiring significant amount of embedded memory. A memory compiler is constructed using the 8T RF bitcell spanning a range of instances from 32 b to 72 Kb. An 8T low-leakage bitcell of 0.106 μm² is used in a 14 nm FinFET technology with a 70 nm contacted gate pitch for high-density (HD) two-port (TP) RF memory compiler which achieves 5.66 Mb/mm² array density for a 72 Kb array which is the highest reported density in 14 nm FinFET technology. The density improvement is achieved by using techniques such as leaf-cell optimization (eliminating transistors), better architectural planning, top level connectivity through leaf-cell abutment and minimizing the number of unique leaf-cells. These techniques are fully compatible with memory compiler usage over the required span. Leakage power is minimized by using power-switches without degrading the density mentioned above. Self-induced supply voltage collapse technique is applied for write and a four stack static keeper is used for read Vmin improvement. Fabricated test chips using 14 nm process have demonstrated 2.33 GHz performance at 1.1 V/25 °C operation. Overall V_min of 550 mV is achieved with this design at 25 °C. The inbuilt power-switch improves leakage power by 12x in simulation. Approximately 8% die area of a leading 14 nm SoC in commercialization is occupied by these compiled RF instances.