Extending the solid solution range of sodium ferric pyrophosphate:Off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)as a novel cathode for sodium‐ion batteries

Iron‐based pyrophosphates are attractive cathodes for sodium‐ion batteries due to their large framework,cost‐effectiveness,and high energy density.However,the understanding of the crystal structure is scarce and only a limited candidates have been reported so far.In this work,we found for the first time that a continuous solid solution,Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2)(0≤α≤1,could be obtained by mutual substitution of cations at center‐symmetric Na3 and Na4 sites while keeping the crystal building blocks of anionic P_(2)O_(7) unchanged.In particular,a novel off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)is thus proposed,and its structure,energy storage mechanism,and electrochemical performance are extensively investigated to unveil the structure–function relationship.The as‐prepared off‐stoichiometric electrode delivers appealing performance with a reversible discharge capacity of 83 mAh g^(−1),a working voltage of 2.9 V(vs.Na^(+)/Na),the retention of 89.2%of the initial capacity after 500 cycles,and enhanced rate capability of 51 mAh g^(−1)at a current density of 1600 mA g^(−1).This research shows that sodium ferric pyrophosphate could form extended solid solution composition and promising phase is concealed in the range of Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2),offering more chances for exploration of new cathode materials for the construction of high‐performance SIBs.

Solid Rocket Booster Thrust Asynchrony Identification Method for Solid Rocket Bundled Rockets With ESO

The role of the rocket attitude control system is to execute the required maneuvers for guidance and ensure the stability of the rocket's flight attitude. Attitude control technology has always been one of the key technologies for ensuring the success of rocket flights and has been a core topic in carrier rocket technology research. The Gravity-1 solid carrier rocket is the first solid rocket bundled rocket developed by China, adopting a configuration with four boosters and a core stage bundled together. During the actual flight process, the four booster engines are ignited first, and then, in the event of insufficient control force from the boosters, the core stage engine is ignited to participate in control. To address thrust asynchrony during the descent of the four boosters, an Extended State Observer(ESO) is employed in the control scheme for this flight segment. This involves real-time estimation and compensation of attitude parameters during flight, identification of thrust asynchrony among the boosters, and simultaneous determination of whether the core stage engine is ignited to participate in control.Through six degrees of freedom simulation analysis and Y1 flight test validation, this method has been proven to be correct and feasible.

水压与动载耦合作用下高铁隧底结构裂损机理分析

高速铁路隧道底部结构隆起变形开裂是多方面影响因素叠加作用的结果。综合利用扩展有限元方法、流固耦合理论和现场实测结果,采用激振力荷载拟合函数施加于轨面模拟列车振动荷载作用效果,分析在水压和列车动荷载耦合作用下的高铁隧道底部结构不协调变形机理,揭示水压与动荷载作用下隧道底部结构的变形特征与水压力变化规律。研究结果表明:在既有隧底结构型式与排水条件下,水压变化是隧道底部结构变形与开裂的诱发原因,列车动荷载导致的裂缝水压交替变化是隧道底部结构持续性隆起裂损的间接原因。隧道底部结构开裂一般首先发生在仰拱填充层中央排水沟处,然后在轨道板、仰拱填充层与衬砌仰拱结构存在刚度差异的各交界面上出现裂缝。高速列车动荷载周期性的上下振动与水压力耦合作用下隧道底部结构界面和各裂缝过水处产生超静水压力,其周期性抽吸变化将对裂缝产生水力压裂效应,加剧隧道底部结构的裂损。高水压高铁隧道底部结构隆起开裂的整治措施应综合考虑泄水降压、裂缝封堵以及底部多层结构体系的层间锚固。

固态变压器中隔离双向DC/DC变换器扩展移相下虚拟电流控制策略

该文以固态变压器后级隔离双向DC/DC变换器为重点研究对象,提出一种扩展移相下虚拟电流控制策略。通过分析后级变换器在扩展移相传输功率下相移量关系以获得最小电流应力最优解来提高变换器的传输效率,减少器件损耗。同时通过虚拟电流控制思想在线估算传输功率来提高系统动态响应性能,减少电流传感器使用。最后,对该文所提出的扩展移相下虚拟电流控制与扩展移相控制进行实验对比分析,验证了扩展移相下虚拟电流控制策略具有降低电流应力,显著提高变换器的动态响应的优点。

Treatment of discontinuous interface in liquid-solid forming with extended finite element method

Extended finite element method(XFEM) is proposed to simulate the discontinuous interface in the liquid-solid forming process.The discontinuous interface is an important phenomenon happening in the liquid-solid forming processes and it is difficult to be simulated accurately with conventional finite element method(CFEM) because it involves solid phase and liquid phase simultaneously.XFEM is becoming more and more popular with the need of solving the discontinuous problem happening in engineering field.The implementation method of XFEM is proposed on Abaqus code by using UEL(user element) with the flowchart.The key is to modify the element stiffness in the proposed method by using UEL on the platform of Abaqus code.In contrast to XFEM used in the simulation of solidification,the geometrical and physical properties of elements were modified at the same time in our method that is beneficial to getting smooth interface transition and precise analysis results.The analysis is simplified significantly with XFEM.

Extended tacrolimus release via the combination of lipid-based solid dispersion and HPMC hydrogel matrix tablets

The objective of this study is to evaluate the feasibility of obtaining extended release of tacrolimus by a novel combination of lipid-based solid dispersion and matrix-type extended release tablet techniques. Tacrolimus solid dispersion was prepared using glycerylbehenate(Compritol~?ATO888) and Pluronic F127 as the carrier materials with hot-melt method, which was then blended with hydrogel matrix materials, such as HPMC and lactose, the powders were directly compressed into tablets. In vitro drug release tests were carried out to evaluate the performance of the solid dispersions and the tablets. The dissolution rate of tacrolimus was significantly improved by the lipid-based solid dispersion, and the incorporation of HPC into the solid dispersion obviously improved its stability after storage. Extended release tablets loaded with tacrolimus solid dispersion showed prolonged drug release patterns over 24 h, the release patterns of the tablets can be tailored by the compositions of the matrix materials, including the types and content of HPMCs. A modified processing method that directly mixed the melted solid dispersion with HPMC powders improved the uniformity of the solid dispersion inside the tablet matrix and release profile. The release data of the extended release tablet fitted well to the Korsmeyer–Peppas model with n value of 0.85, which suggested diffusion-and erosion-controlled release mechanism. The combination of lipid-based solid dispersion and HPMC hydrogel matrix may find wide applications in the extended release dosage forms of high potent, water-insoluble drugs.

基于SolidWorks的电力光缆捆扎机的虚拟样机设计研究

光缆捆扎机是智能电网信息化的信息通信工程施工中的关键设备。应用SolidWorks三维建模软件完成捆扎机零部件的建模,并应用虚拟装配技术得到捆扎机的虚拟样机模型。设计的结果表明捆扎机可以满足施工要求,具有一定的指导意义。

Overview of extended release tacrolimus in solid organ transplantation

Tacrolimus(Prograf?, Astellas Pharma Europe Ltd, Staines, United Kingdom; referred to as tacrolimusBID) is an immunosuppressive agent to prevent and treat allograft rejection in kidney transplant recipients in combination with mycophenolate mofetil, corticosteroids,with or without basiliximab induction. The drug has also been studied in liver, heart and lung transplant; however, these are currently off-label indications. An extended release tacrolimus formulation(Advagraf?, Astagraf XL?) allows for once-daily dosing, with the potential to improve adherence. Extended release tacrolimus has similar absorption, distribution, metabolism and excretion to tacrolimus-BID. Phase Ⅰ pharmacokinetic trials comparing extended release tacrolimus and tacrolimus-BID have demonstrated a decreased maximum concentration(C max) and delayed time to maximum concentration(t max) with the extended release formulation; however, AUC0-24 was comparable between formulations. Overall extended release tacrolimus has a very similar safety and efficacy profile to tacrolimus-BID. It is not recommended in the use of liver transplant patient's due to the increased risk of mortality in female recipients. There has been minimal data regarding the use of extended release tacrolimus in heart and lung transplant recipients. With the current data available for all organ groups the extended release tacrolimus should be dosed in a 1:1 fashion, the exception may be the cystic fibrosis population where their initial dose may need to be higher.

Effect of original microstructures on microstructural evolution of A2017 semi-solid alloy billets during reheating

The microstructural evolution of the A2017 semi-solid alloy billets provided with rheocasting and extruding/extending forming by shearing-cooling-rolling(SCR) technology during reheating in semi-solid state was investigated. The microstructural differences and their generation causes for both billets were also analyzed. The results show that during reheating, the grains of rheocasting billets grow up and spheroidize gradually with the prolongation of isothermal holding time, the eutectic liquid phase at low melting point forms mainly among the grains. However, the grains of the extruding/extending forming billets grow up abnormally through grain coalescence in the initial stage of the reheating, the entrapment of large amount of liquid within grains occurs, and the grain sizes in the reheating billets are coarse and inhomogeneous. Compared with extruding/extending forming billets, rheocasting billets have smaller and uniform grains in reheating microstructure and can rapidly form liquid phase among grains. Therefore, rheocasting billets are more suitable for the semi-solid forming than the extruding/extending forming billets.

Microstructure variation and growth mechanism of hypoeutectic Al-Si alloy solidifi ed under high pressure

The microstructure of hypoeutectic Al-9.21wt.%Si alloy solidified under 5.5 GPa was studied.The results show that the solidifi cation microstructure is refi ned.The primary α phase is the extended solid solution.The solid solubility of Si in α phase is up to 8.26wt.%.The growth mode of the α phase is cellular,and this cellular growth mechanism is interpreted in terms of the decrease of the diffusivity and the extended solid solution under high pressure.By calculation,it can be known that the the diffusivity of solute in the liquid under normal pressure is as high as two hundred times that under high pressure.The microhardness of the hypoeutectic Al-Si alloy solidif ied under high pressure is higher than that of solidifi ed under normal pressure.After annealing,Si precipitates from the solid solution,the microhardness of the alloy decrease,but,still higher than that of solidif ied under normal pressure.

Continuous Extruding Extending Forming of Semi-solid A2017 Alloy

Continuous extruding/ extending formiug process for A2017 alloy in semi-solid state was proposed through installing extending die at the outlet of shearing- cooling- rolling （SCR） machine. A series of experiments to produce fiat bar of A2017 alloy were carried oat. The forming process, metal flow behavior in die and microstructure and mechanical property of prodacts were investigated. It is shown that if the pouring temperature of melt was higher, the die was filled with semi-solid slurry with low solid fraction and periodical cracks would occur on the product surface ; If its pouring temperature was lower or the preheating temperature of die was lower, semisolid slurry would solidify rapidly and block the die after entering the cavity. The analysis of mass flow trace shows that the semi-solid slurry move forward layer by layer and fills the die extending cavity in radiation manner and the velocity of mass flow in the central area of extending cavity and exit of mould is the maximum, and then decreases gradually from the center to both sides of die wall. By inereasiug the die extending angle, the velocity of mass flow becomes more homogeneous. Under rational process control and die design, the A2017 fiat bar with transverse section of 10 × 50 mm and with good surface and fine equiaxed grains can be obtained by continuous extruding/extending forming process. The product＇s tensile strength and elongation are 420.5 MPa and 14.2% , respectively.

超长电力电缆隧道固壁遮挡对土壤热库吸热特征的影响

为探究电力电缆隧道通风设计中土壤热库吸热量简化计算方法的误差和适用范围,采用数值计算方法对隧道传热过程进行三维模拟研究。通过定义切向导热偏差率,量化评价简化计算方法所采用的一维传热假设与实际传热过程的偏差,分析现行简化计算方法在隧道内壁不同遮挡情况下的误差和适用性。结果表明:1)隧道内壁遮挡区边缘位置的切向导热偏差率最高达95%;2)双层隧道的下层空间,由于内壁面被遮挡程度大,使得土壤热库传热呈现典型的二维特征,简化计算方法误差高达57.5%;3)上层空间内壁面遮挡较少,传热过程与简化计算方法所做的一维假设类似,故计算误差仅约10%,这表明隧道土壤热库吸热量现行简化计算方法仅适用于双层隧道的上层空间,但不适用于下层空间。

不同后扩链剂对无溶剂型高固含水基聚氨酯的影响

分别以水、乙二胺(EDA)、异佛尔酮二胺(IPDA)、二乙烯三胺(DETA)、N-β-(氨乙基)-γ-氨丙基甲基二甲氧基硅烷(KH-602)和聚醚胺(D-230)为后扩链剂,制备一系列无溶剂高固含水基聚氨酯,研究不同后扩链剂对水基聚氨酯的乳液性能(乳液稳定性、粒径大小、乳液黏度)、成膜性能(耐水耐溶剂性、力学性能、热稳定性、玻璃化转变温度)及应用性能(常温耐折牢度、热粘性、耐温性)的影响。结果表明,在较高R值(—NCO/—OH摩尔比)条件下,采用后扩链法可制备无溶剂、高固含水基聚氨酯,其热力学性能满足应用需求。其中,含环状结构的后扩链剂如IPDA可提高聚氨酯力学性能和耐温性;含交联功能的后扩链剂如DETA与KH602可提高聚氨酯耐水耐溶剂性及涂层抗热粘性和耐温性;而含柔性链的后扩链剂如D-230所制备的聚氨酯具有非常低的模量,适合制备非常柔软的聚氨酯。

黏土岩中水泥锚固体滑脱的有限-离散元模型初探

锚固体与围岩有效黏结是保证锚杆(索)系统正常工作的重要前提,为研究黏土岩内水泥锚固体在拉拔荷载作用下的滑移脱黏机理,开展黏土岩三轴试验、黏土岩-水泥砂浆界面直剪试验和水泥锚固体拉拔的物理模型试验,基于有限-离散元方法(FDEM),建立黏土岩-水泥砂浆的二元体模型,对水泥锚固体拉拔过程进行模拟。研究表明:黏土岩黏聚力小于黏土岩-水泥砂浆界面的切向黏结强度,低法向压力时二元体的剪切破坏多为黏土岩的剪切破坏,但黏土岩内摩擦角较大,高法向压力下界面抗剪强度低于黏土岩,二元体剪切破坏逐渐转变为界面脱黏;考虑剪切失效的双线性黏聚力模型在模拟软岩破坏时是适用的,而二元体黏结界面更适合通过黏结-摩擦模型模拟;水泥锚固体拉拔失效过程可分为黏结变形阶段,界面脱黏阶段,剪胀咬合阶段和滑移阶段4个阶段,界面脱黏后,锚固体附近黏土岩的剪切破坏也是导致锚固失效的重要因素,剪胀咬合阶段的咬合力决定了锚固体的峰值抗拔能力。研究结果对于软岩地区锚固结构设计有一定的指导作用。

绳控多模块固面天线展开动力学分析与优化

针对一种扭簧驱动的双绳控固面天线,建立了基于欧拉-拉格朗日方程的天线展开动力学模型,研究了绳索张力对天线展开运动参数的影响。对绳控天线反射面系统的完整展开过程进行动力学仿真,得到仿真中的展开情况与数值计算结果相符,验证了理论模型的正确性。为了使天线反射面充分展开,采用序列二次规划算法(sequential quadratic programming,SQP)分别在无绳和有绳控制系统中,对驱动扭簧进行优化设计,通过优化使得展开更为合理并减少了反射面的展开包络空间。研究表明,通过引入绳索系统能够提高天线展开过程的稳定性,有效降低了各铰链关节处的负载峰值。研究结果可为绳控固面天线的展开过程设计提供理论指导,并具有实际工程意义。

基于SPDMD算法的XLPE电缆介质响应参数辨识

为进一步解析获取表征交联聚乙烯(cross-linked polyethylene,XLPE)电缆绝缘介质内部弛豫、电导过程的特征参数,从而定量评估其绝缘状态,该研究以极化电流谱线为研究对象,提出一种基于稀疏增强动态模态分解(sparsity-promoting dynamic mode decomposition,SPDMD)的介质扩展Debye等效电路模型参数辨识计算方法。首先,从采集极化电流中计算得出增强稀疏幅值向量;随后利用介质响应真实模态对应向量元素非零的特征,辨识得出扩展Debye模型支路数量;最后实现对支路元件参数进行计算。结果表明,该方法相较于传统方法辨识精度更高;此外,根据极化/去极化电流测试的自身特性,相较于传统针对去极化电流进行参数辨识的方式,将极化电流作为辨识对象更为准确可靠,这一观点也在仿真及实测结果中得到验证。

锂离子电池回收利用规范的国别比较与中国进路

由于资源稀缺和对使用锂离子电池设备需求的增长,锂离子电池越来越多地应用于各行各业中,因此电池元件的回收利用可能在未来发挥越来越大的作用。本文中,笔者对比分析了欧盟、美国关于锂离子电池回收利用的规范,以及中国现行的制度框架和规范政策。由此得知,锂离子电池回收利用规范的中国进路可以是扩大电池生产者责任,明确分配回收责任,对回收外的环节进行适当规制。以此完善中国锂离子电池回收利用的相关做法,为锂离子电池回收利用提供法律保障,提升电池回收利用的法治化程度,配合“双碳”战略目标的实现。

实心分割铝合金导体高压电缆的设计与研究

为实现以铝代铜在高压交联电缆领域中的应用,并解决多股绞合的铝分割导体在接头处发生蠕变变形的现象,研究了一种实心分割铝合金导体的高压电缆。通过对实心分割铝合金导体的结构设计、产品工艺技术研究、工艺装备研究、产品性能研究及试验分析,结果表明,实心分割铝合金导体高压电缆的导体电阻相对偏差均在±0.5%以内。

运载火箭电缆自适应布局技术研究

电气系统是运载火箭的重要组成部分,传统火箭布局是将仪器设备布局和电缆走线两个阶段串联运行的设计模式,布局方式大多都依靠经验,割裂了仪器布局与电缆走线之间的耦合关系,不仅效率较低,而且可能造成电缆总重量难以有效优化,从而降低运载火箭的运载能力。本文提出一种基于智能算法的仪器电缆自适应快速布局技术,将设备布局和电缆走线协同优化设计,实现壳段上仪器电缆的快速、智能设计,从而大幅提升设计效率,该技术已成功应用到我国最大的固体运载火箭“力箭一号”设计中,火箭在2022年7月27日完成圆满首飞。