Defect Engineering:Can it Mitigate Strong Coulomb Effect of Mg^(2+)in Cathode Materials for Rechargeable Magnesium Batteries?

Rechargeable magnesium batteries(RMBs)have been considered a promising“post lithium-ion battery”system to meet the rapidly increasing demand of the emerging electric vehicle and grid energy storage market.However,the sluggish diffusion kinetics of bivalent Mg^(2+)in the host material,related to the strong Coulomb effect between Mg^(2+)and host anion lattices,hinders their further development toward practical applications.Defect engineering,regarded as an effective strategy to break through the slow migration puzzle,has been validated in various cathode materials for RMBs.In this review,we first thoroughly understand the intrinsic mechanism of Mg^(2+)diffusion in cathode materials,from which the key factors affecting ion diffusion are further presented.Then,the positive effects of purposely introduced defects,including vacancy and doping,and the corresponding strategies for introducing various defects are discussed.The applications of defect engineering in cathode materials for RMBs with advanced electrochemical properties are also summarized.Finally,the existing challenges and future perspectives of defect engineering in cathode materials for the overall high-performance RMBs are described.

Automated Dimensioning Method of Engineering Drawings for Mechanical Products Based on Curve Chain

An automated method based on the curve chain was proposed for dimensioning of engineering drawings for the mechanical products.According to the internal relation between the features of 3D model feature and elements of 2D drawing,the curve chain was established to reflect the geometric topological structure between the elements.It divides the dimensions into the absolute dimensions within the cure chain and the relative dimensions between the curve chains.The parallel and lengthy relationship between the drawing elements of the constructed X and Y parallel matrix was solved to remove redundant elements in the curve chain and labeled the absolute dimensions of the remaining valid elements.The average minimum weight coefficient was introduced to judge the dependence on the relative dimensions between curve chains.Through the analysis of the overlap between the circular rectangular areas,including all the absolute dimensions of the curve chains,overlapping curve chains were merged,and their dimensions were rearranged to avoid the cross interference between them.The method was seamlessly integrated into the drafting module of product design software NX,and it developed an automated dimensioning system.The examples show that the system has excellent interactivity and robustness in the dimensioning of product engineering drawings.The dimension information is complete,accurate and reliable.

Teaching Reform and Practice in Engineering Drawing Based on 3D Modeling with Computer

Based on the necessity of three dimensional modeling with computer in teaching reform, this paper is the summarization of reform practice of teaching engineering drawing in our institute. The teaching reform begins with three dimensional modeling that used computer instead of board. On the basis of target of teaching reform, set of teaching content, arrangement of class hour and teaching method, the research of teaching practice have been done, and very good effects in teaching of engineering drawing have been achieved.

Combination of Splicing Visualization and Assembling Visualization in Engineering Drawing Education Carried by Self-optimizing Student Presentation

A pioneering self-optimizing teaching method in student-centric seminars was introduced in this paper, in which each student will establish preferred engineering drawing process directed by educators and necessary principles. We presented the working-memory centered mechanism in mental aspect to explain the phenomena. The theoretical mechanism is based on the typical translation between orthographic projection image and perspective image. The first is bonding object into a whole solid. The second is splicing the selected surfaces of objects and tailored them together. Two study groups were determined： an experimental group, who were directed to combine the object-based and surface-based construction methods in the presentations, and a control group, who learned through regular presentations made by an experienced teacher during the same period. The results showed that a significant enhancement in average scores has been achieved in the test among the experimental group in comparison with the control group. The variance of the scores is obviously reduced through the self-optimizing learning strategy, indicating a significant advantage on filling up the ability gaps among students. In fact, the results also indicated that the educator did keep the lesson in high quality. But it is worthy of more attention that the difference of mental manipulation habits between some students and educator may lead to a polarization in score distribution. So the seminar is a promising method to help the students to combine the object-based and surface-based construction methods.

An Optimum and Effective Drawing Teaching System in Engineering

In this study, the authors shall illustrate the difficulties, pros and cons of ＂Technical Drawing＂ courses in engineering curriculums. The authors also show the efficiency, effectiveness of students＇ grasping the engineering drawing concepts in depth. The authors have conducted a survey on students and their instructors for teaching the course. Whether the course should be taught with manual handling and then computerized or starting with computer aid and finishing the content of the course, the authors shall also go in detail of syllabus how the drawing rooms and aid tools will be. This part of study shall look into the ergonomics, safety and conditions of classrooms. Responses of 300 students will be shared in this presentation. Statistical analysis will detect the effects of different factors involved in the questionnaire.

Detecting Adjacent Relativity of Engineering Drawing Entities with Container Window

Automatic recognition and interpretation of engineering drawing plays an important role in computer aided engineering. Detecting the positional relation between entities is an important topic in this research field. In this paper the concepts of adjacent relativity and container window of drawing entities were proposed. By means of container window, the adjacent irrelative entities can be detected quickly and effectively, which speeds up the process of adjacent relativity detection. Meanwhile, the algorithm of adjacent relativity detection was discussed.

Research on Teaching Reform of Architectural Engineering Drawing Based on BIM Technology

The course of architectural engineering drawing is the basic course before the students of civil engineering related majors study the professional courses.It aims to cultivate the students’ability of configuration,expression,reading and drawing.BIM Technology simulates the real component information of a building through digital information simulation,and flexibly transforms between two-dimensional and threedimensional,providing a new tool for the teaching of architectural engineering drawing.This paper analyzes the characteristics of BIM Technology and teaching advantages,combined with the current teaching situation of architectural engineering drawing course,puts forward reform suggestions and implementation process,and provides reform ideas for the teaching of engineering basic courses.

The First Professional Work on Descriptive Geometry and Engineering Drawing in China

The book ＂Selected Papers on Descriptive Geometry and Construction Drawing＂ was published by the joint efforts of three institutions （the Association for Science and Technology of Hubei Province, Hubei Province Cartographic Association, Hubei Science and Technology Information Institute） in 1965. It is the first collection of papers on construction drawing, representing the accomplishments of the research of the field in the 1960s in China. This paper describes its historical background, contents and val- He.

Raster to Vector Conversion for Engineering Drawings:Survey and Prospect

Recent development and recognition methods of raster to vector conversion for engineering drawings are presented. The advantages and disadvantages of all existing models are analyzed. Some research challenges and future directions are discussed.

对“一带一路”来华留学生进行双语教学的实践与启示--以《Civil Engineering Drawing》为例

疫情期间,笔者对“一带一路”来华留学生进行了《Civil Engineering Drawing》课程的双语教学,在这个过程中发现了一些问题并进行了反思。

Evaluation of Environmental Sound Pressure Level,Drawing of Noise-Isosonic Map Using Surfer V.19,and Prioritization of Engineering Noise Control Methods Using the Analytic Hierarchy Process(AHP):A Field Study in CGS Stations

Noise pollution is one of the most significant harmful physical factors in the industrial and occupational environments.Due to the high costs of exposure to excessive noise;continuous sound evaluation,propose and implement noise control plans in occupational environments is necessary.Thus,the present study aimed to review environmental sound measurements,drawing of noise maps,and prioritizing the engineering noise control methods using the Analytic Hierarchy Process(AHP).This study was a descriptive-analytical study that aimed to assess occupational noises and present a control plan in the City Gas Stations(CGSs)of Kerman,Iran in 2021.The present study was done in two phases.In the first phase,six CGSs were investigated to measure and evaluate the noise.In addition,the noise map of a CGS was drawn using the Surfer software.Finally,the AHP was used in the second phase of the research to prioritize the control measures.In this phase,four criteria and ten alternatives were identified.According to first phase results,the sound pressure level(SPL)of the stations varied from 76 to 98 dBA.Besides,the majority of the studied stations had a sound level higher than 85 dBA(danger zone).The second phase of the study showed that out of the four evaluated criteria,the executability criterion had the highest impact and the cost criterion had the lowest impact on the selection of control measures with a weight of 0.587 and 0.052,respectively.Based on the results of prioritization of the alternatives,using a silenced regulator(weight of 0.223)and increasing the thickness of the tube(weight of 0.023)had the highest and lowest priorities among the alternatives,respectively.The use of engineering noise control methods such as using silenced regulators was the best way to control the noises of CGSs.Additionally;it is noteworthy that AHP is a practical method for prioritizing alternatives to achieve the most accurate decision-making.The results of AHP can be of great help to health and safety experts and managers in choosing the sound engineering control measures more precisely.

Parametric Drawing of Bearing Engineering Drawings based on Auto LISP

As the secondary development language of Auto CAD,Auto LISP is widely used in the standard rendering of various complex graphics.This method uses Auto LISP as a tool to select and draw three common bearings according to the matched spindles.This paper describes the key steps of bearing parametric drawing and implementation process in detail.This developed program simplifies the drawing process,reduces the repetitive work in the design,and improves the efficiency of drawing.

Key Technology in Developing Web-Based Engineering Drawing CAI Software

Key techniques to improve the quality of developing Web-based engineering drawing CAI software are discussed and some experience in applying commercial tools for generating vector drawing, concise representation of 3D solids, real-time interactive animation, data management etc. is illustrated. A Web-based Engineering Drawing CAI software 'Solid Projection' has been implemented by using these techniques.

A New Solution for Feature Recognition from 2D Engineering Drawing

The paper presents a promised way of feature recognition from 2D engineering drawing——developing special system and extracting features from machining drawings. In general, researchers inclined to extract features from design drawings and ignored machining drawings. Actually, both of machining and design information shows the same importance in developing new products. Not only can machining drawing provide us with feature model or 3D geometrical model of the part, but also they can be easily recognized. In the paper the processes and methods of feature recognition from three-cone-bit (A Kind of aiguilles used to drill oil well) machining drawings are introduced. Firstly, overall approach is explained. Secondly, two methods of form feature recognition are introduced: symbol-matching method used to analyze annularity or chained graph and method based on feature-hint used to recognize the general features. Thirdly, feature parameters are extracted. Finally, a practical implementation is given.

Engineering Drawing Education Reform and Digital Technology

The way of reform and development of Engineering Drawing education is explored. Such activities have been carried out for 5 years, and great progress in the update of course contents, teaching methods and other related aspects is achieved. A series of textbooks, multimedia CD and established a Web site for Engineering Drawing course have been published. The efforts to realize an advanced contemporary teaching mode are being made. With the support of multimedia software and resources over Internet, students become the real main body of study, the teaching qualities are supervised and controlled throughout, and the students?imagination and ability of design and drawing are greatly enhanced. All reform is built on digital technology.

Biomimetic natural biomaterials for tissue engineering and regenerative medicine:new biosynthesis methods,recent advances,and emerging applications

Biomimetic materials have emerged as attractive and competitive alternatives for tissue engineering(TE)and regenerative medicine.In contrast to conventional biomaterials or synthetic materials,biomimetic scaffolds based on natural biomaterial can offer cells a broad spectrum of biochemical and biophysical cues that mimic the in vivo extracellular matrix(ECM).Additionally,such materials have mechanical adaptability,micro-structure interconnectivity,and inherent bioactivity,making them ideal for the design of living implants for specific applications in TE and regenerative medicine.This paper provides an overview for recent progress of biomimetic natural biomaterials(BNBMs),including advances in their preparation,functionality,potential applications and future challenges.We highlight recent advances in the fabrication of BNBMs and outline general strategies for functionalizing and tailoring the BNBMs with various biological and physicochemical characteristics of native ECM.Moreover,we offer an overview of recent key advances in the functionalization and applications of versatile BNBMs for TE applications.Finally,we conclude by offering our perspective on open challenges and future developments in this rapidly-evolving field.

Compositional and Hollow Engineering of Silicon Carbide/Carbon Microspheres as High-Performance Microwave Absorbing Materials with Good Environmental Tolerance

Microwave absorbing materials(MAMs)characterized by high absorption efficiency and good environmental tolerance are highly desirable in practical applications.Both silicon carbide and carbon are considered as stable MAMs under some rigorous conditions,while their composites still fail to produce satisfactory microwave absorption performance regardless of the improvements as compared with the individuals.Herein,we have successfully implemented compositional and structural engineering to fabricate hollow Si C/C microspheres with controllable composition.The simultaneous modulation on dielectric properties and impedance matching can be easily achieved as the change in the composition of these composites.The formation of hollow structure not only favors lightweight feature,but also generates considerable contribution to microwave attenuation capacity.With the synergistic effect of composition and structure,the optimized SiC/C composite exhibits excellent performance,whose the strongest reflection loss intensity and broadest effective absorption reach-60.8 dB and 5.1 GHz,respectively,and its microwave absorption properties are actually superior to those of most SiC/C composites in previous studies.In addition,the stability tests of microwave absorption capacity after exposure to harsh conditions and Radar Cross Section simulation data demonstrate that hollow SiC/C microspheres from compositional and structural optimization have a bright prospect in practical applications.

Defect engineering in transition-metal(Fe,Co,andNi)-based electrocatalysts for water splitting

Electrocatalytic water splitting seems to be an efficient strategy to deal with increasingly serious environmental problems and energy crises but still suffers from the lack of stable and efficient electrocatalysts.Designing practical electrocatalysts by introducing defect engineering,such as hybrid structure,surface vacancies,functional modification,and structural distortions,is proven to be a dependable solution for fabricating electrocatalysts with high catalytic activities,robust stability,and good practicability.This review is an overview of some relevant reports about the effects of defect engineering on the electrocatalytic water splitting performance of electrocatalysts.In detail,the types of defects,the preparation and characterization methods,and catalytic performances of electrocatalysts are presented,emphasizing the effects of the introduced defects on the electronic structures of electrocatalysts and the optimization of the intermediates'adsorption energy throughout the review.Finally,the existing challenges and personal perspectives of possible strategies for enhancing the catalytic performances of electrocatalysts are proposed.An in-depth understanding of the effects of defect engineering on the catalytic performance of electrocatalysts will light the way to design high-efficiency electrocatalysts for water splitting and other possible applications.

Interface Engineering of Titanium Nitride Nanotube Composites for Excellent Microwave Absorption at Elevated Temperature

Currently,the microwave absorbers usually suffer dreadful electromagnetic wave absorption(EMWA)performance damping at elevated temperature due to impedance mismatching induced by increased conduction loss.Consequently,the development of high-performance EMWA materials with good impedance matching and strong loss ability in wide temperature spectrum has emerged as a top priority.Herein,due to the high melting point,good electrical conductivity,excellent environmental stability,EM coupling effect,and abundant interfaces of titanium nitride(TiN)nanotubes,they were designed based on the controlling kinetic diffusion procedure and Ostwald ripening process.Benefiting from boosted heterogeneous interfaces between TiN nanotubes and polydimethylsiloxane(PDMS),enhanced polarization loss relaxations were created,which could not only improve the depletion efficiency of EMWA,but also contribute to the optimized impedance matching at elevated temperature.Therefore,the TiN nanotubes/PDMS composite showed excellent EMWA performances at varied temperature(298-573 K),while achieved an effective absorption bandwidth(EAB)value of 3.23 GHz and a minimum reflection loss(RLmin)value of−44.15 dB at 423 K.This study not only clarifies the relationship between dielectric loss capacity(conduction loss and polarization loss)and temperature,but also breaks new ground for EM absorbers in wide temperature spectrum based on interface engineering.

Ionization Engineering of Hydrogels Enables Highly Efficient Salt‑Impeded Solar Evaporation and Night‑Time Electricity Harvesting

Interfacial solar evaporation holds immense potential for brine desalination with low carbon footprints and high energy utilization.Hydrogels,as a tunable material platform from the molecular level to the macroscopic scale,have been considered the most promising candidate for solar evaporation.However,the simultaneous achievement of high evaporation efficiency and satisfactory tolerance to salt ions in brine remains a challenging scientific bottleneck,restricting the widespread application.Herein,we report ionization engineering,which endows polymer chains of hydrogels with electronegativity for impeding salt ions and activating water molecules,fundamentally overcoming the hydrogel salt-impeded challenge and dramatically expediting water evaporating in brine.The sodium dodecyl benzene sulfonate-modified carbon black is chosen as the solar absorbers.The hydrogel reaches a ground-breaking evaporation rate of 2.9 kg m−2 h−1 in 20 wt%brine with 95.6%efficiency under one sun irradiation,surpassing most of the reported literature.More notably,such a hydrogel-based evaporator enables extracting clean water from oversaturated salt solutions and maintains durability under different high-strength deformation or a 15-day continuous operation.Meantime,on the basis of the cation selectivity induced by the electronegativity,we first propose an all-day system that evaporates during the day and generates salinity-gradient electricity using waste-evaporated brine at night,anticipating pioneer a new opportunity for all-day resource-generating systems in fields of freshwater and electricity.