Optimal design and scheduling of an integrated centralized and decentralized energy generation system

Most electricity worldwide is supplied from the established centralized energy generation (CEG) system network which mainly operates using fossil fuels. An alternative decentralized energy generation (DEG) system has emerged with the advantage of generating electricity from locally available resources (usually renewable energy) for local consumption. DEG systems could avoid significant power losses during transmission in the CEG network and reduce the reliance on fossil fuels. These DEGs however, are geographically scattered and their resources are intermittent. One notable problem is that, at one point of time, some DEGs may have excess electricity and some may have electricity deficits; depending on the resource availability and the electricity consumption pattern. Weather-depending resources such as solar and wind energy could also affect the system’s reliability. The energy gaps between one DEG to another can be solved, provided that the DEGs are integrated at the distribution level whereas the reliability issue can be overcome by integrating multiple DEGs to the existing CEG (which has a more stable electricity supply) at the transmission level. To deploy this complex integrated energy system, key decision parameters such as selection of technologies and their capacities, interactions between different units, overall system efficiency and costing at their optimum level have to be determined. There are limited studies in the literature regarding the wide-scale integration of DEGs with CEG and a lack of comprehensive optimization approach to solve for the system’s design and scheduling. To fill these gaps, this research aimed to develop a novel targeting and optimization methodology for the design and scheduling of the DEG-CEG integrated energy system. A new numerical DEG-CEG integration framework was developed based on two enhanced Power Pinch approaches: (i) Extended Power Pinch Analysis for on-grid DEG system, and (ii) Extended Electrical Power System Cascade Analysis for CEG system with generation flexibility. The numerical framework optimized only the system’s energy efficiency. A mixed integer nonlinear programming (MINLP) model was then developed to study the DEG-CEG system more holistically in terms of energy efficiency and costing, as well as to validate the optimal solutions resulted from the numerical framework. Both approaches were demonstrated using a hypothetical case study – an integrated energy system with multiple DEGs (operating using solar, wind and biomass energy) at different locations connected to one CEG (operating using natural gas) to fulfil power demand from residential, commercial and industrial sectors. From energy-efficient aspect, the numerical framework resulted in the system operating at an efficiency of 77 %, while the MINLP model showed 80.7 %. The difference of 3.7 % confirms the relevance of the numerical DEG-CEG integration framework as a systematic and effective energy planning tool in solving the design and scheduling problems of a power system. In term of costing, the MINLP model revealed that the system can achieve 77 % with a total cost of RM 936 million/y. Nevertheless, the numerical method is still an important analytical tool as the analysis provides visual insights that can be easily understood and appreciated by users like energy engineers and policymakers

Stable nontrivial Z2 topology in ultrathin Bi (111) films: a first-principles study

Recently, there have been intense efforts in searching for new topological insulator (TI) materials. Based on first-principles calculations, we find that all the ultrathin Bi (111) films are characterized by a nontrivial Z2 number independent of the film thickness, without the odd-even oscillation of topological triviality as commonly perceived. The stable nontrivial Z2 topology is retained by the concurrent band gap inversions at multiple time-reversal-invariant k-points and associated with the intermediate inter-bilayer coupling of the multi-bilayer Bi film. Our calculations further indicate that the presence of metallic surface states in thick Bi(111) films can be effectively removed by surface adsorption.Comment: 5 pages, 3 figure

Horndeski Gravity and the Violation of Reverse Isoperimetric Inequality

We consider Einstein-Horndeski-Maxwell gravity, together with a cosmological constant and multiple Horndeski axions. We construct charged AdS planar black holes in general dimensions where the Horndeski anxions span over the planar directions. We analyse the thermodynamics and obtain the black hole volumes. We show that the reverse isoperimetric inequality can be violated, implying that these black holes can store information more efficiently than the Schwarzschild black hole.Comment: Latex, 25 pages, 1 figure, references adde

Joint RNN Model for Argument Component Boundary Detection

Argument Component Boundary Detection (ACBD) is an important sub-task in argumentation mining; it aims at identifying the word sequences that constitute argument components, and is usually considered as the first sub-task in the argumentation mining pipeline. Existing ACBD methods heavily depend on task-specific knowledge, and require considerable human efforts on feature-engineering. To tackle these problems, in this work, we formulate ACBD as a sequence labeling problem and propose a variety of Recurrent Neural Network (RNN) based methods, which do not use domain specific or handcrafted features beyond the relative position of the sentence in the document. In particular, we propose a novel joint RNN model that can predict whether sentences are argumentative or not, and use the predicted results to more precisely detect the argument component boundaries. We evaluate our techniques on two corpora from two different genres; results suggest that our joint RNN model obtain the state-of-the-art performance on both datasets.Comment: 6 pages, 3 figures, submitted to IEEE SMC 201

KCRC-LCD: Discriminative Kernel Collaborative Representation with Locality Constrained Dictionary for Visual Categorization

We consider the image classification problem via kernel collaborative representation classification with locality constrained dictionary (KCRC-LCD). Specifically, we propose a kernel collaborative representation classification (KCRC) approach in which kernel method is used to improve the discrimination ability of collaborative representation classification (CRC). We then measure the similarities between the query and atoms in the global dictionary in order to construct a locality constrained dictionary (LCD) for KCRC. In addition, we discuss several similarity measure approaches in LCD and further present a simple yet effective unified similarity measure whose superiority is validated in experiments. There are several appealing aspects associated with LCD. First, LCD can be nicely incorporated under the framework of KCRC. The LCD similarity measure can be kernelized under KCRC, which theoretically links CRC and LCD under the kernel method. Second, KCRC-LCD becomes more scalable to both the training set size and the feature dimension. Example shows that KCRC is able to perfectly classify data with certain distribution, while conventional CRC fails completely. Comprehensive experiments on many public datasets also show that KCRC-LCD is a robust discriminative classifier with both excellent performance and good scalability, being comparable or outperforming many other state-of-the-art approaches

Central placenta previa with placenta percreta partially invading bladder: a case report

Placenta previa, placenta accreta, increta and percreta are increasing day by day due to increased number of cesarean sections now days, but central placenta previa with placenta percreta invading bladder is a very rare obstetrical complication. A case of central placenta previa with placenta percreta partially invading bladder in woman who was G2P1L1 with 32+6 weeks of gestation and with history of previous cesarean section is presented in this manuscript. The patient was managed with intrapartum cesarean hysterectomy with bilateral ureter J stents and bladder repair following cesarean delivery of a preterm baby. Total estimated blood loss was 6000 mL. The patient was discharged on 28th December 2014 that is 29th day of admission with a healthy baby. The aim of this study is to bring awareness of such case and to discuss the risk factor, presentation, diagnosis, management and choice of anesthesia for the same