Challenges, Trends and Solutions for Communication Networks and Cyber-Security in Smart Grid.

Power grid is one of the most important manifestations of the modern civilization and the engine of it where it is described as a digestive system of the civil life. It is a structure has three main functions: generation, transmission lines, distribution. This concept was appropriate for a century. However, the beginning of the twenty-first century brought dramatic changes on different domains: media, human growth, economic, environmental, political, and technical etc. Smart grid is a sophisticated structure including cyber and physical bodies hence it reinforces the sustainability, the energy management, the capability of integration with microgrids, and exploiting the renewable energy resources. The quantum leap of smart grid is related to the advanced communication networks that deal with the cyber part. Moreover, the communication networks of smart grid offer attractive capabilities such as monitoring, control, and protection at the level of real time. The wireless communication techniques in integration frame are promised solution to compensate the requirements of smart grid designing such as wireless local area networks, worldwide interoperability for microwave access, long term evolution, and narrowband- internet of things. These technologies could provide high capacity, flexibility, low-cost maintenance for smart grid. However, the multi-interfaces in smart grid may exploit by persons or agencies to implement different types of cyber-attacks may lead to dangerous damage. This research paper reviews the up-to-date researches in the field of smart grid to handle the new trends and topics in one frame in order to offer integration vision in this vital section. It concentrates on the section of communication networks the mainstay of smart grid. This paper discusses the challenging and requirements of adopting the wireless communication technologies and delves deeply into literature review to devise and suggest solutions to compensate the impairments efficiently. Moreover, it explores the cyber security that representing the real defiant to implement the concept of smart grid safely.

Output Power Modeling of Wind Turbine Based on State Curve Analysis

Background: In wind power generation, the power curve can reflect the overall power generation performance of a wind turbine. How to make the power curve have high precision and be easy to interpret is a hot research topic. Objective: Because the current power curve modeling method is not comprehensive in feature selection, the simplified model and state curve of a wind turbine are introduced to avoid feature selection and make the model interpret easily. Methods: A power modeling method based on different working conditions is proposed. The wind turbine system is simplified into three physical models of blades, mechanical transmission and generator, and the energy transfer is expressed by mathematical expressions. The operation process of the wind turbine is divided into three phases: constant power (CP), constant speed (CS), and maximum power point tracking (MPPT), and the power expression of each phase is given after the analysis of state curves. Results: The effectiveness of the proposed method is verified by the supervisory control and data acquisition (SCADA) data of a 2MW wind turbine. The experimental results show that the mean absolute percentage error (MAPE) index of the proposed power modeling method based on state curve analysis is 11.56%, which indicates that the power prediction result of this method is better than that of the sixth-order polynomial regression method, whose MAPE is 13.88%. Conclusion: The results show that the proposed method is feasible with high transparency and is interpreted easily.

Study on the fire resistance of concrete-filled steel tubular column to composite beam joints after earthquake damage

Background: Post-earthquake fire is one of the secondary disasters caused by the earthquake; many earthquakes around the world have brought about severe fires and led to enormous losses. It is of great significance to study the fire resistance of structures after earthquake to improve the level of urban disaster prevention and reduce the fire loss. Methods: A nonlinear finite element model of composite joints subjected to post-earthquake fires is established based on ABAQUS software. The state after the earthquake damage is imported into the thermal-stress analysis model through the restart request in ABAQUS, and considered as the initial state of the thermal-stress analysis model. Results: It is noticed that when the damage index is less than 0.517, the damage level shows significant effect on the fire resistance, but the influence is no longer significant when the damage index reaches 0.781. When only the column is exposed to fire, the column showed obvious local buckling and overall bending deformation. Meanwhile, when the joint area below the concrete slab is exposed to fire, the joint shows a mixed failure mode of the excessive vertical displacement of beam end and column instability. Conclusion: The fire resistance of the composite joint decreases gradually with the increase of seismic damage level. The fire condition has a significant effect on the fire resistance of the composite joints; with the increase of fire area, the fire resistance of composite joints with same damage degrees decreases gradually.

Current research developments of electromagnetic joining technology in China-A review

: With the increasing applications of multi-material structures in lightweight vehicle, traditional joining techniques are highly challenged in joining dissimilar materials. To meet the requirements of the multi-material structure of lightweight design, electromagnetic joining (EMJ) technology including electromagnetic riveting (EMR) and magnetic pulse welding (MPW) developed rapidly in recent years, which can achieve good connection performance for complex-shaped structures and dissimilar materials. This paper presents a comprehensive review of the research progress of the EMJ technology in China. Moreover, this review aims at providing a guideline for researchers engaged in electromagnetic joining technology and other connecting processes to further improve the level of lightweight vehicle design and manufacture. Firstly, the development history and status of EMJ was presented. Then the basic joining principles and characteristics of EMR and MPW were analyzed in detail. Subsequently, the investigation of joints formation mechanism, mechanical properties of joints and equipment development of EMR and MPW techniques were reviewed and analyzed. Especially, the operating principle is described along with various factors affecting the mechanical and microcosmic properties of joints. Finally, the future development trend of the EMJ technology based on the current research progress is highlighted.

An approach of estimating the effect of replacement of conventional vehicles by L-category vehicles on fuel consumption and emissions

Background and Objective: In order to investigate the effect of electric L-category vehicles (EL-Vs) on traffic characteristics of urban roads, fuel consumption and exhaust emissions, existing technologies including traffic characteristics, vehicle performance were used. Methods: The relations among traffic density, traffic flow, and traffic speeds were reviewed based on the real test data in different areas. Results: One of the test data was chosen to get the mathematical equations between traffic density and traffic speed for congested urban roads. Conclusion: Then, the equations were used to estimate the reductions of vehicle fuel consumption and exhaust emissions brought by the improved traffic situation due to the applications of ELVs.

Improved Control Volume Method for Thermoelastic Analysis of Functionally Graded Solids

In this work, an improved control volume finite element method (ICVFEM) is proposed and implemented for thermoelastic analysis in functionally graded materials (FGMs) at steady state. Different from the conventional CVFEM, the sub-control volume used in the proposed method is a circular in the intrinsic coordinate. The advantages of the new integral domain are: (i) the complex integration path can be avoided, (ii) the method is very suitable for many types of elements. High-order shape functions of eight quadrilateral (Q8) elements are used to obtain the unknown variables and their derivatives. Besides, material properties in a functionally graded structure are calculated by the high-order shape functions based on the properties defined at the node. To verify the convergence and accuracy of the proposed method, three numerical examples with analytical solutions are illustrated by using the conventional CVFEM and FEM at the same time.

Computational Methods Dedicated for Neurological Disorder Detection through Epistasis Analysis: A Review

Background: Neurological disorders diseases such as ALS, Alzheimer’s, epilepsy, Parkinson’s Disease, Autism, Atrial Fibrillation, and Sclerosis affect the central nervous system, including the brain, nerves, spinal cords, muscles, and Neuromuscular joint. These disorders are investigated by detecting the genetic variations in Single Nucleotide Polymorphism (SNP) in Genome-Wide Association Studies (GWAS). In the human genome sequence, one SNP influence the effects of another SNP. These SNP-SNP interactions or Gene-Gene interaction (Epistasis) significantly increases the risk of disease susceptibility to neurological disorders. Objective: The manual analyzes of various genetic interactions related to Neurological diseases are cumbersome. Hence, the computational system is effective for the discovery of Epistasis effects in Neurological syndromes. This study aims to explore various techniques of statistical, machine learning, optimization, so far applied to find the epistasis effect for neurological-disorder. Conclusion: This study finds several genetic interactions models involving different loci, various candidate genes, and SNP interactions involved in numerous neurological diseases. The gene APOE and its polymorphism increase Alzheimer's disease pathology. The gene GAB2 and its SNPs play a vital role in Alzheimer’s disease. The genes GABRA4, ITGB3, and SLC64A highly influence the genetic interactions for Autism disorder. In schizophrenia, the SNPs of NRG1 increases the disease risk. The benefits, limitations, and issues of the various computational techniques implemented for epistasis evaluation of neurological disease are deeply discussed.

One-post Solvothermal Synthesis of Bismuth Oxybromides for Efficient Visible-light Photocatalytic Degradation of Methyl Parahydroxybenzoate: Effects of Alkaline and Reaction Medium

Background: The development of high-efficiency visible-light-active photocatalysts to eliminate emerging contaminants is of great significance for environmental remediation and personal safety. Methods: In this work, BiOBr and two oxygen-rich bismuth oxybromide (Bi4O5Br2-EG and Bi4O5Br2-H2O) were synthesized by solvothermal method through the reaction of Bi3+ and Br- in different reaction medium (ethylene glycol or water) and alkali conditions. The composition, structure, morphology, light absorption, surface area, and surface feature of the synthetic bismuth oxybromides were systematically characterized. Due to the presence of ethylene glycol and OH-, the Bi4O5Br2-EG preferentially exposes the 010 facets. The formation of hierarchical flower-like structures of Bi4O5Br2- EG can be elucidated by the dissolution-recrystallization-growth mechanism. The bismuth oxybromides were then used for photocatalytic degradation of methyl parahydroxybenzoate (a commonly used preservative but exposes endocrine disrupting activity) under visible-light irradiation. Results: Since Bi4O5Br2-EG has a satisfactory band structure (bandgap energy ~2.61 eV, valence band potential +2.45 V), high surface area (49.0 m2g-1), and negatively charged surface, its photocatalytic removal efficiency of MPHB is 46.5 and 41.2 times that of BiOBr and Bi4O5Br2-H2O, respectively. During the photodegradation reaction, holes and superoxide radicals were recognized as the key reactive oxide species. Conclusion: In addition, the as-synthesized Bi4O5Br2-EG is stable and easy to reuse, suggesting it is a potential candidate for wastewater treatment.

An approach to improving the mechanical properties of friction stir spot welded joints on the basis of hook formation mechanism

Background: Partial metallurgical bond (namely 'hook') is formed between the overlapped metal sheets during friction stir spot welding (FSSW). The geometry of hook is found to significantly affect the mechanical performance of FSSWed joints, while that how to adjust hook geometry to a better state remains to be studied. Methods: The conventional FSSW joints under different plunge depths and dwelling time were obtained. The cross-sectional morphology of each spot weld was investigated to clarify the material flow behavior and deduce the formation mechanism of hook. The tensile shear strength and fracture features were examined to reveal the effect of hook geometry on the mechanical properties. Results: The weld geometry affects the tensile shear strength of FSSWed joints by determining their fracture modes. The formation mechanism of hook is deduced by a material flow model. In the tool-plunging stage, the faying interface is broken by upward-flowing materials, hook is therefore initiated and driven up gradually. During the tool-dwelling stage, hook continues to migrate to the low-pressure zone, surrounding the stir zone. Conclusion: The uncertainty of crack-propagating endpoint along hook makes it difficult to ensure the mechanical properties of welds. If the hook endpoint has not yet reached the low-pressure zone at the end of welding process, welds with ideal hook geometry can be obtained. Target friction stir spot welds were produced by the use of a tool possessing smaller pin diameter.