Switched Reluctance Motor: Research Trends and Overview

There has been a growing interest in switched reluctance motor(SRM)ever since the development of thyristor in 1956.The most appealing feature of SRM which attracts researchers over these years is its simple structure that incorporates concentrated windings on the stator poles and plain laminations of ferromagnetic material as a rotor.Due to this attributes,advances are being made rapidly with the consideration that SRM can be used as an alternative to DC motors and permanent magnet motors.The objective of this paper is to present an overview of the recent developments and a prediction of possible future advancements in SR Drives.Brief history,importance,innovations in structure and control,along with practical application examples are all discussed here to give a more in-depth comprehension of the motor.

Programmed DNA walkers for biosensors

Nowadays,due to excellent biological and polymeric characteristics,DNA has been widely noted as an emerging building block to construct diverse materials for biosensing,in vivo imaging,drug delivery,and disease therapy.Particularly,relying on programmability,predictability,and stability of DNA,DNA walkers have opened new and exciting opportunities in modern life sciences for target detection and biological analysis,which are constructed by self-assembly of DNA or combining DNA with other nanomaterials(e.g.,quantum dots,gold nanoparticles,magnetic nanoparticles,polymers).Compared with conventional nanomaterials(lanthanide-doped upconversion nanoparticles,magnetic nanomaterials,carbon dots,silicon dots,and so on),DNA walkers showed convenient modification,lower biotoxicity,excellent biocompatibility and high biostability,improving the biological application.Meanwhile,with high-speed operating efficiency and sustainable operation,DNA walkers powered by strand displacement reaction or protein enzyme/DNAzyme reaction,have highly sensitive detection and signal amplification abilities,which are applied in biosensing,material assembly and synthesis,and early cancer diagnosis.Worthily,DNA walkers could be regarded as signal amplifiers,which enhanced the signal transduction and amplified biosensor sensing signals.Herein,we systematically and comprehensively summarized the operating principles of various DNA walkers,categorized rational design of the DNA walker,and outlined the application of DNA walker in biosensors.Furthermore,the challenges and future trends of DNA walkers were discussed.

A critical review of key materials and issues in solid oxide cells

Solid oxide cells(SOCs)are all solid ceramic devices with the dual functionality of solid oxide fuel cells(SOFCs)to convert the chemical energy of fuels like H2,natural gas and other hydrocarbons to electricity and of solid oxide electrolysis cells(SOECs)to store renewable electric energy of sun and wind in hydrogen fuel.Among the electrochemical energy conversion and storage devices,SOCs are the most clean and efficient technology with unique dual functionality.Due to the high operation temperature(typically 600–800°C),SOCs exhibit many advantages over other energy conversion devices,such as low material cost,high efficiency and fuel flexibility.There has been rapid development of SOC technologies over the last decade with significant advantages and progress in key materials and a fundamental understanding of key issues such as an electrode,electrolyte,performance degradation,poisoning,and stack design.The reversible polarization also has a critical effect on the surface segregation and stability of the electrode and electrode/electrolyte interface.This critical review starts with a brief introduction,working principles and thermodynamics of SOC technology to readers with interests in this rapidly developing and emerging field.Then the key materials currently used in SOCs are summarized,followed by the discussion of the most advanced electrode modification methods and critical issues of SOCs,including the surface chemistry,segregation,electrode/electrolyte interface and varying material degradation mechanisms under reversible operations.The challenges and prospects of SOC technology for future developments are discussed.

Overview of Research and Development Status of Brushless Doubly-Fed Machine System

The brushless doubly-fed machine(BDFM)has been widely used due to its advantages of robustness,reliable operation,ease of maintenance,adjustable power factor,small converter capacity and low cost.BDFM is attractive for use in many applications such as variable frequency speed regulation systems and variable speed constant frequency generation systems.Hence,there is a rapidly growing interest in design and control of BDFM.In this paper,the origin and development of BDFM are reviewed,the structural characteristics of BDFM are discussed at length,the principles of operation and design are analyzed,and the different control methods used for BDFM are overviewed and compared in detail.Finally,challenges and opportunities of BDFM are concluded.

Strategies of Efficient Exploration and Development of Deepwater Oil and Gas Overseas

Deepwater offshore area,with rich oil and gas resources,has currently become the hot area for oil and gas exploration and the main battlefield where global oil majors compete with each other.This article summarizes the current situation of deepwater oil and gas exploration and development overseas from the perspectives of exploration history,exploration achievements and technical progress,and analyzes the difficulties and challenges faced by the industry,such as low level understanding of hydrocarbon accumulation conditions,global security and environmental challenges.And then,several feasible implementation strategies have been proposed on how to actively deal with the challenges,promote Chinese oil companies' overseas exploration,and realize efficient exploration and development of deepwater oil and gas fields overseas.These strategies consist of three aspects:profit-oriented operation principle,exploration ideas supported by theory and technology,and exploration strategy that puts safety first.In the era of low oil prices,Chinese oil companies must build up confidence,seize the opportunity and face the challenge while taking efforts to innovate technologies and theories,updates strategic ideas,and cultivate deepwater talents so as to be in an active position in global deepwater exploration and development industry in the future.

A Review on the Heat Pipe Photovoltaic/Thermal(PV/T)System

The Photovoltaic/thermal(PV/T)system combines the conventional PV panel with solar collector into one integrated system,which could achieve the function of generating power and providing thermal energy at the same time.Recently,it has become the most promising solar system for building applications.Most of the PV/T systems use water as the coolant,which could cause freezing problem in winter.To overcome this problem,the heat pipe PV/T system is developed to provide electrical and thermal energy stably without the seasonal barrier.Although some published review works have involved this type of PV/T system,they just stated a simple introduction on it,acting as a small part of their works.This paper focuses on the heat pipe PV/T system independently and provides a comprehensive and in-depth analysis of its performance.Firstly,the structure and operational principles of the heat pipe PV/T module and system are introduced concisely.Then the features and performance of different types of heat pipe PV/T systems,i.e.,integral heat pipe,loop heat pipe,and pulsating heat pipe PV/T system,are presented and analyzed.This is followed by the review on the performance of the systems which combine heat pipe PV/T module and other devices.Finally,the research gaps in this field are identified,and some future research trends and directions are recommended.