Intelligent Identification over Power Big Data:Opportunities,Solutions,and Challenges

The emergence of power dispatching automation systems has greatly improved the efficiency of power industry operations and promoted the rapid development of the power industry.However,with the convergence and increase in power data flow,the data dispatching network and the main station dispatching automation system have encountered substantial pressure.Therefore,themethod of online data resolution and rapid problemidentification of dispatching automation systems has been widely investigated.In this paper,we performa comprehensive review of automated dispatching of massive dispatching data from the perspective of intelligent identification,discuss unresolved research issues and outline future directions in this area.In particular,we divide intelligent identification over power big data into data acquisition and storage processes,anomaly detection and fault discrimination processes,and fault tracing for dispatching operations during communication.A detailed survey of the solutions to the challenges in intelligent identification over power big data is then presented.Moreover,opportunities and future directions are outlined.

Expanded models of the project portfolio selection problem with learning effect

This research develops two new models for project portfolio selection, in which the candidate projects are composed of multiple repetitive units. To reflect some real situations, the learning effect is considered in the project portfolio selection problem for the first time. The mathematical representations of the relationship between learning experience and investment cost are provided. One numerical example under different scenarios is demonstrated and the impact of considering learning effect is then discussed.

Lebesgues-Stieltjes Integrals of Fuzzy Stochastic Processes with Respect to Finite Variation Processes

Let be a fuzzy stochastic process and be a real valued finite variation process. We define the Lebesgue-Stieltjes integral denoted by for each by using the selection method, which is direct, nature and different from the indirect definition appearing in some references. We shall show that this kind of integral is also measurable, continuous in time t and bounded a.s. under the Hausdorff metric.

AN EXTENDED MODEL FOR PROJECT PORTFOLIO SELECTION WITH PROJECT DIVISIBILITY AND INTERDEPENDENCY

In this paper, we develop an extended model for the project portfolio selection problem over a planning horizon with multiple time periods. The model incorporates the factors of project divisibility and interdependency at the same time for real-life applications. The project divisibility is considered as a strategy, not an unfortunate event as in the literature, in choosing the best execution schedule for the projects, and the classical concept of＂project interdependencies＂ among fully executed projects is then extended to the portions of executed projects. Additional constraints of reinvestment consideration, setup cost, cardinality restriction, precedence relationship and scheduling are also included in the model. For efficient computations, an equivalent mixed integer linear programming representation of the proposed model is derived. Numerical examples under four scenarios are presented to highlight the characteristics of the proposed model. In particular, the positive effects of project divisibility are shown for the first time.

Can energy storage make off-grid photovoltaic hydrogen production system more economical?

Under the ambitious goal of carbon neutralization,photovoltaic(PV)-driven electrolytic hydrogen(PVEH)production is emerging as a promising approach to reduce carbon emission.Considering the intermittence and variability of PV power generation,the deployment of battery energy storage can smoothen the power output.However,the investment cost of battery energy storage is pertinent to non-negligible expenses.Thus,the installation of energy-storage equipment in a PVEH system is a complex trade-off problem.The primary goals of this study are to compare the engineering economics of PVEH systems with and without energy storage,and to explore time nodes when the cost of the former scenario can compete with the latter by factoring the technology learning curve.The levelized cost of hydrogen(LCOH)is a widely used economic indicator.Represented by seven areas in seven regions of China,results show that the LCOH with and without energy storage is approximately 22.23 and 20.59 yuan/kg in 2020,respectively.In addition,as technology costs drop,the LCOH of a PVEH system with energy storage will be less than that without energy storage in 2030.

Vitreous Humor:A Review of Biochemical Constituents in Postmortem Interval Estimation

Postmortem changes in the biochemical constituents of the vitreous humor have been widely used to estimate the postmortem interval(PMI)over the past several decades.However,few reviews have summarized the relationship between the postmortem vitreous biochemical constituents and time of death.Herein,the relationship between PMI and single biochemical components,including vitreous potassium,hypoxanthine,and amino acids,as well as comparisons of each statistical parameter in the formula,is summarized.We also discuss other compounds such as urea and uric acid,which have no direct relationship with PMI.Utility of multiple constituent simultaneous analysis for estimating PMI is being increasingly investigated.The promising idea of using simultaneous analysis of multiple constituents to determine PMI is proposed as a future research direction.