Evaluation on Configuration Stiffness of Overconstrained 2R1T Parallel Mechanisms

Currently,two rotations and one translation(2R1T)three-degree-of-freedom(DOF)parallel mechanisms(PMs)are widely applied in five-DOF hybrid machining robots.However,there is a lack of an effective method to evaluate the configuration stiffness of mechanisms during the mechanism design stage.It is a challenge to select appropriate 2R1T PMs with excellent stiffness performance during the design stage.Considering the operational status of 2R1T PMs,the bending and torsional stiffness are considered as indices to evaluate PMs'configuration stiffness.Subsequently,a specific method is proposed to calculate these stiffness indices.Initially,the various types of structural and driving stiffness for each branch are assessed and their specific values defined.Subsequently,a rigid-flexible coupled force model for the over-constrained 2R1T PM is established,and the proposed evaluation method is used to analyze the configuration stiffness of the five 2R1T PMs in the entire workspace.Finally,the driving force and constraint force of each branch in the whole working space are calculated to further elucidate the stiffness evaluating results by using the proposed method above.The obtained results demonstrate that the bending and torsional stiffness of the 2RPU/UPR/RPR mechanism along the x and y-directions are larger than the other four mechanisms.

Progress in carbon dioxide separation and capture: A review

This article reviews the progress made in CO2 separation and capture research and engineering. Various technologies, such as absorption, adsorption, and membrane separation, are thoroughly discussed. New concepts such as chemical-looping combustion and hydrate-based separation are also introduced briefly. Future directions are suggested. Sequestration methods, such as forestation, ocean fertilization and mineral carbonation techniques are also covered. Underground injection and direct ocean dump are not covered.

Surface spinel reconstruction to suppress detrimental phase transition for stable LiNi_(0.8)CO_(0.1)Mn_(0.1)O_(2) cathodes

Nickel-rich layered oxides are attractive cathode for lithium-ion batteries(LIBs)because of the high energy density and low cost.The critical problem is capacity fading caused by the highly reactive metastable phases under voltages of higher than 4.15 V.Herein,we find that facile Ar/H2 plasma treating could produce oxygen vacancies that will readily transform into homogeneous spinel layer(~6 nm)on the LiNi_(0.8)CO_(0.1)Mn_(0.1)O_(2)(NCM811)surface after a few cycles of lithiation/delithiation procedure.Owing to the structural matching between spinel and layered structure,the diffusion of Li ions could remain fast upon cycling.Besides,the spinel layer is electrochemically inert,which guarantees surface stabilization and inhibits the detrimental phase transition from H2 to H3 at high voltages.Under the protection of the homogeneous spinel layer,the NCM_(811) electrode shows superior capacity retention of 91.2% after 200 cycles at the current density of 100 mA·g^(−1).This work proposes a novel strategy of surface reconstruction to stabilize nickel-rich layered oxide materials for LIBs.

Recent advances in switchable surfactants for heavy oil production:A review

Surfactants are extensively employed in the cold production of heavy oil.However,producing heavy oil emulsions using conventional surfactants poses a challenge to spontaneous demulsification,necessitating the addition of demulsifiers for oil-water separation.This inevitably increases the exploitation cost and environmental pollution risk.Switchable surfactants have garnered much attention due to their dual capabilities of underground heavy oil emulsification and surface demulsification.This study focuses on the fundamental working principles and classification of novel switchable surfactants for oil displacement developed in recent years.It offers a comprehensive overview of the latest advances in the applications of switchable surfactants in the fields of enhanced oil recovery(EOR),oil sand washing,and oil-water separation.Furthermore,it highlights the existing challenges and future development directions of switchable surfactants for heavy oil recovery.

Chemical looping based ammonia production--A promising pathway for production of the noncarbon fuel

Ammonia, primarily made with Haber-Bosch process developed in 1909 and winning two Nobel prizes, is a promising noncarbon fuel for preventing global warming of 1.5 °C above pre-industrial levels. However,the undesired characteristics of the process, including high carbon footprint, necessitate alternative ammonia synthesis methods, and among them is chemical looping ammonia production(CLAP) that uses nitrogen carrier materials and operates at atmospheric pressure with high product selectivity and energy efficiency. To date, neither a systematic review nor a perspective in nitrogen carriers and CLAP has been reported in the critical area. Thus, this work not only assesses the previous results of CLAP but also provides perspectives towards the future of CLAP. It classifies, characterizes, and holistically analyzes the fundamentally different CLAP pathways and discusses the ways of further improving the CLAP performance with the assistance of plasma technology and artificial intelligence(AI).

Inaugural statement on the first issue

As an indispensable basic element for the civilization and development of the economy,copper-based new materials are of strategic importance required for scientific and technological advances,leading to the development of strategic emerging industries such as electronics,aerospace,high-end equipment manufacturing,renewable energy and biomedicine.It is of great significance to carry out comprehensively the basic and applied research on new copper-based materials in an all-round manner,for the purpose of promoting the innovation and integrated development of advanced technologies in copperrelated fields,adapt to emerging cross-field disciplines and talent training.