Problems and Barriers Impeding the Implementation of MagLev Assisted Aircraft Take-Off and Landing Concept

Nowadays, the success of the new technology development and deployment process depends not only on technical, technological solutions, but also on solving the non-technological problems and crossing the societal and psychological barriers. A large international European projects, GABRIEL1 had developed a maglev assisted aircraft take-off and landing, that was applied to conceptual design of aircraft and required on-board and ground systems, had analysed all impacts (effects of concept deployment on effectiveness, safety, security, noise, emissions) and had demonstrated the safe applicability by concept validation. The applied methodology, used methods and the results of the Gabriel projects had been described and discussed by 55 project deliverables. This paper has a special goal: investigating the problems and barriers of possible implementing of the radically new technology, aircraft MagLev assisted take-off and landing. The study was started by identification and classification of the problems and barriers. After it, the problems were systematically analysed by use of special methodology containing the understanding (description) of the problems, investigation of the possible solutions and discussing their applicability (mainly by use of the Gabriel project results). The paper has three major sections: 1) description of the Gabriel concept and project results, 2) introducing some related thoughts on general aspects of new technology developments, and 3) discussion on the problems and their solutions. The major classes of the problems are the 1) technical, technological problems as developing a radically new solution, landing the undercarriage-less aircraft on the magnetic tracks, 2) stakeholders’ problems as decision makers kicking against supporting the developments of so radically new technologies and 3) society barriers like society worrying on and fear of future passengers on flying by aircraft have not conventional undercarriage systems. The paper will show that these problems have safe and cost-effective solutions.

The Influence of Climate Change and Variability on Aircraft Take-off and Landing Performance;a Case Study of the Abeid Amani Karume International Airport-Zanzibar

Climate change (CC) and variability have been world widely reported to pose number of risks in aviation industry including accidents, astray, and other operational difficulties. The impact of weather on landing and take-off performances has been several times experienced at Abeid Amani Karume International Airport (AAKIA);however, the influence of climate change and variability to the aircraft performance needs to be assessed. Thus, this study investigated the influence of climate change and variability on aircrafts take-off and landing performances. Specifically, the study investigated;i) the influence of climate change on Take-off Distance Required (TODR) and Maximum Take-off Mass (MTOM) for different types of aircraft;ii) the influence of climate variability to the aircraft landing performance on light, medium and heavy aircraft and lastly, iii) the study investigated the seasonal and annual variability on aircraft landing performance due to climate variability. The datasets used in this study include the eight years (2014-2021), aircraft operational records (diversion and missed approach events) and Aviation Routine Weather Reports (METAR) records which were utilized as the indicators for landing performance, the long-term (1990-2020) annual maximum temperatures (Tmax) which was used to determine the TODR and MTOM. Statistical tools including mean, percentage changes, correlations, regression, and the chi-square test were used for analysis and hypotheses testing. The results revealed that light and medium aircraft categories were significantly most affected on diversion events as compared to the heavy categories;however, for the missed approach events the impact was vice versa. Moreover, the seasonal and annual variability on diversion and missed approach events were significantly different (at p ≤ 0.001). As for the take-off performance, results show that the TODR and MTOM were significantly increasing and decreasing (at p ≤ 0.001), based on increasing air temperatures. Therefore, the study concludes that the changing climate has significantly affected aircraft by increasing the TODR and decreasing the MTOM, while the climate variability has significantly affected landing performance by influencing the diversion and missed approach events. Thus, the study recommends (i) further research works including the feasibility study on runway extension for the safety of future aircraft operations at the AAKIA and (ii) proper maintenance and improvement of the Instrumental Landing Systems (ILS) as an adaptation measures to the landing aircraft during bad weather events.

PARAMETRIC MODELING OF COMPONENT LIBRARY FOR LANDING GEAR BASED ON CATIA/CAA

The design of landing gear is complicated due to the numerous considered elements.And the initial elements related to each other can also be influenced by different factors.Landing gear design often involves a very large variety of configurations,especially in the conceptual design phase.However,traditional method costs more time to complete the whole procedure for suitable configurations of landing gears.Therefore,the parametric modeling of component library for landing gear based on computer aided three-dimensional interface application/component application architecutre(CATIA/CAA)is proposed.According to the analysis of the characteristics of landing gear components,a method is presented to extract the primary parameters of landing gear components so that a systematic classification can be established.Further,the related theories and methods,including receiving geometrical parameters of the components and updating the parametrical model,displaying the component parts,are also illustrated.Finally,the development technology for component library is explained.The proposed modeling method can improve the efficiency of the whole design cycle for landing gear.

高质量发展视角下的安徽省城市建设用地利用效率时空演变分析

为了研究安徽省城市建设用地利用效率在我国高质量发展视角下的时空演变情况,本文通过构建城市建设用地利用效率评价体系,并选取2006—2020年安徽省相关指标数据,运用三阶段DEA模型,把产业结构协调、技术进步协调、内外发展协调均纳入进环境因素,借此从时空2个维度对安徽省城市建设用地利用效率进行定量分析,并对安徽省非DEA有效设区市的城市建设用地投入及其产出指标进行投影分析。研究结果表明:1)从时间维度上看,2006—2020年安徽省的城市建设用地利用效率均处于较高水平,但上升趋势逐渐减缓,该省Malmquist全要素生产率变化指数的均值为1.023,技术进步是提升安徽省城市建设用地利用效率的主要驱动力量。2)从空间维度上看,安徽省城市建设用地高水平利用效率的空间分布主要沿着西北—东南城市带(淮北-淮南-合肥-铜陵)与西南-东北城市带(六安-滁州)大致成十字状对称布局,并且随着时间的推移,安徽省城市建设用地高水平利用效率还会沿着西北—东南、西南-东北2条轴线呈十字状向外扩散,其中在皖北地区主要以淮北、淮南2座资源型城市为核心向周边扩张,在皖南与江淮地区主要以芜湖、合肥2座交通枢纽城市为核心向周边扩张。3)通过冗余分析发现,安徽省城市建设用地利用效率主要受到城市产业协调发展和绿色协调发展的影响。在投入方面,城市第二、第三产业从业人数冗余是制约着安徽省城市建设用地利用效率提升的主要因素;在产出方面,安徽省各设区市的产业结构不合理、生态产出不足,以及资源配置不当等问题也均是制约着安徽省城市建设用地利用效率提升的重要因素。

基于长短期记忆神经网络模型的多步滚动预测方法

飞机着陆阶段是各飞行阶段中风险最大的阶段之一,可能会遇到阵风、跑道入侵、硬着陆和跑道超限等不安全事件。较长的着陆距离会增加着不安全事件发生的风险。为了降低发生不安全事件的风险,利用长短期记忆(long short term memory,LSTM)神经网络捕获时间序列飞行数据对时间的依赖性,研究了一种多步滚动预测策略来预测飞机着陆距离以进行实时预警,飞机着陆预测模型用于预测着陆距离。结果表明:与单步预测相比,该方法可以更好地捕捉飞行参数的时间变化。通过多组仿真实验验证基于LSTM神经网络模型的多步滚动预测方法的准确性与有效性。

景电一期灌区土地利用变化及驱动力分析

研究利用2000、2010、2020年3期Globeland 30土地覆盖数据,结合资料收集、现场调研、土地利用转移矩阵法、土地利用动态度法等研究方法,分析2000、2010、2020年土地利用变化特征;根据2007—2020年景电一期灌区社会经济数据,运用SPSS主成分分析法对土地利用变化及驱动力进行分析。结果表明:灌区地类主要以耕地和裸地为主,占总面积的85%以上;2000—2010年,人造地表、湿地、水体面积分别减少14.74 km^(2)、0.97 km^(2)、0.13 km^(2);2010—2020年,人造地表面积增加36.35 km^(2);整个研究期(2000—2020年),灌区综合土地利用动态度为0.25%,人造地表和水体面积分别增加21.61 km^(2)和0.48 km^(2);景电一期灌区土地利用变化主要驱动力为产业、经济和人口变化。研究成果可为灌区水土资源高效利用奠定基础。

Integrated visual navigation based on angles-onlymeasurements for asteroid final landing phase

Visual navigation is imperative for successful asteroid exploration missions.In this study,an integrated visual navigation system was proposed based on angles-only measurements to robustly and accurately determine the pose of the lander during the final landing phase.The system used the lander's global pose information provided by an orbiter,which was deployed in space in advance,and its relative motion information in adjacent images to jointly estimate its optimal state.First,the landmarks on the asteroid surface and markers on the lander were identified from the images acquired by the orbiter.Subsequently,an angles-only measurement model concerning the landmarks and markers was constructed to estimate the orbiter's position and lander's pose.Subsequently,a method based on the epipolar constraint was proposed to estimate the lander's inter-frame motion.Then,the absolute pose and relative motion of the lander were fused using an extended Kalman filter.Additionally,the observability criterion and covariance of the state error were provided.Finally,synthetic image sequences were generated to validate the proposed navigation system,and numerical results demonstrated its advance in terms of robustness and accuracy.

全自动固相萃取-高效液相色谱-串联质谱法测定耕地周边地表水中6种嘧啶类杀菌剂的残留量

提出了全自动固相萃取-高效液相色谱-串联质谱法测定耕地周边地表水中乙嘧酚、嘧菌环胺、氟嘧菌胺、嘧菌腙、嘧霉胺、氯苯嘧啶醇等6种嘧啶类杀菌剂残留量的方法。分取预处理后的地表水样品500 mL,调节酸度至pH(7.00±0.05),以18 mL·min^(-1)流量过活化好的HLB固相萃取柱(500 mg/12 mL),用体积比1:1的甲醇-乙腈混合溶液洗脱,收集洗脱液,于45℃氮吹至近干,加入甲醇1 mL复溶,涡旋混匀后上机检测。结果表明:6种嘧啶类杀菌剂的质量浓度均在0.01~5.00μg·mL^(-1)内与对应的质谱响应值呈线性关系,检出限(3S/N)为0.007~0.033μg·L^(-1);按照标准加入法进行回收试验,回收率为84.8%~102%,测定值的相对标准偏差(RSD,n=5)为1.5%~3.6%,重复性RSD(n=6)为1.9%~2.9%。

Prognostics for Lithium-ion batteries for electric Vertical Take-off andLanding aircraft using data-driven machine learning

The health management of batteries is a key enabler for the adoption of Electric Vertical Take-off and Landingvehicles (eVTOLs). Currently, few studies consider the health management of eVTOL batteries. One distinctcharacteristic of batteries for eVTOLs is that the discharge rates are significantly larger during take-off andlanding, compared with the battery discharge rates needed for automotives. Such discharge protocols areexpected to impact the long-run health of batteries. This paper proposes a data-driven machine learningframework to estimate the state-of-health and remaining-useful-lifetime of eVTOL batteries under varying flightconditions and taking into account the entire flight profile of the eVTOLs. Three main features are consideredfor the assessment of the health of the batteries: charge, discharge and temperature. The importance of thesefeatures is also quantified. Considering battery charging before flight, a selection of missions for state-ofhealth and remaining-useful-lifetime prediction is performed. The results show that indeed, discharge-relatedfeatures have the highest importance when predicting battery state-of-health and remaining-useful-lifetime.Using several machine learning algorithms, it is shown that the battery state-of-health and remaining-useful-lifeare well estimated using Random Forest regression and Extreme Gradient Boosting, respectively.

农户劳动力转移规模对土地流转的影响

探讨农户劳动力转移规模对土地流转的影响,对发展现代化农业与城乡一体化具有重要意义。利用2018年中国家庭追踪调查(CFPS)农户样本数据,以社会网络为工具变量,运用IV-Probit模型,实证分析了农户劳动力转移规模对土地流转的作用。研究结果表明:劳动力转移规模对土地流转具有阶段性影响,即仅当劳动力转移规模>0.42时,劳动力转移才会显著促进土地流转;家庭中购买金融产品的可能性越大、教育程度越高都会促进土地流转行为;社会网络与劳动力转移规模存在相关关系。为促进土地流转发展,政府应完善劳动力市场及异地社会保障体制、更新农业信贷产品、鼓励农户学习相关政策与职业技能、加大非农就业机会宣传力度。

欠驱动VTOL飞行器的自耦PID控制方法

针对非最小相位欠驱动垂直起降(vertical taking-off and landing, VTOL)飞行器的控制难题,提出了一种自耦PID(auto-coupling proportional-integral-differrential, ACPID)控制理论方法.首先通过坐标变换将VTOL飞行器的质心映射为Huygens振动中心,不仅能实现新系统控制输入解耦,而且也能避免非最小相位VTOL飞行器零动态不稳定的问题;然后对Huygens振动中心分别设计纵横向位置的ACPID控制器,并分别获得VTOL飞行器底部推力和滚转姿态角虚拟指令,进而设计滚转姿态角的ACPID控制器形成滚转力矩,从而实现VTOL飞行器系统的位置跟踪控制;最后通过复频域分析理论证明闭环控制系统的鲁棒稳定性和抗扰动鲁棒性.理论分析和仿真结果都表明了本文方法的有效性,在非最小相位欠驱动控制系统领域具有重要的科学意义和广泛的应用前景.

基于实时动态载波相位差分的无人机起降引导系统研制

中程固定翼无人机在起降阶段高精度定位,要求实时计算无人机下滑道与固定基准站之间高精度的相对定位基线,以引导无人机精确起降.基于全球卫星导航系统(GNSS)实时动态载波相位差分(RTK)技术、无线链路数传电台技术,设计了固定基准站无人机起降引导系统.起降引导系统在静态零基线、动态飞行条件下,RTK引导系统与固定基准站之间相对定位精度达到水平方向≤0.03 m(1σ),高程方向≤0.05 m(1σ).试验结果表明,无人机起降引导系统达到了厘米级定位精度,满足中程固定翼无人机在起降阶段对高精度定位的要求.

A multi-strategy pigeon-inspired optimization approach to active disturbance rejection control parameters tuning for vertical take-off and landing fixed-wing UAV

In this paper.Active Disturbance Rejection Control(ADRC)is utilized in the pitch control of a vertical take-off and landing fixed-wing Unmanned Aerial Vehicle(UAV)to address the problem of height fluctuation during the transition from hover to level flight.Considering the difficulty of parameter tuning of ADRC as well as the requirement of accuracy and rapidity of the controller,a Multi-Strategy Pigeon-Inspired Optimization(MSPIO)algorithm is employed.Particle Swarm Optimization(PSO),Genetic Algorithm(GA),the basic Pigeon-Inspired Optimization(PIO),and an improved PIO algorithm CMPIO are compared.In addition,the optimized ADRC control system is compared with the pure Proportional-Integral-Derivative(PID)control system and the non-optimized ADRC control system.The effectiveness of the designed control strategy for forward transition is verified and the faster convergence speed and better exploitation ability of the proposed MSPIO algorithm are confirmed by simulation results.

Development of a Bird-like Flapping-wing Aerial Vehicle with Autonomous Take-off and Landing Capabilities

The lack of autonomous take-off and landing capabilities of bird-like flapping-wing aerial vehicles(BFAVs)seriously restricts their further development and application.Thus,combined with the current research results on the autonomous take-off and landing technology of unmanned aerial vehicles,four types of technologies are studied,including jumping take-off and landing technology,taxiing take-off and landing technology,gliding take-off and landing technology,and vertical take-off and landing(VTOL)technology.Based on the analytic hierarchy process(AHP)-comprehensive evaluation method,a fuzzy comprehensive evaluation model for the autonomous take-off and landing scheme of a BFAV is established,and four schemes are evaluated concretely.The results show that under the existing technical conditions,the hybrid layout VTOL scheme is the best.Furthermore,the detailed design and development of the prototype of a BFAV with a four-rotor hybrid layout are carried out,and the vehicle performance is tested.The results prove that through the four-rotor hybrid layout design,the BFAV has good autonomous take-off and landing abilities.The power consumption analysis shows that for a fixed-point reconnaissance mission,when the mission radius is less than 3.38 km,the VTOL type exhibits longer mission duration than the hand-launched type.

基于SPH法的返回舱入水载荷模拟分析

返回舱水上着落前期面临较大砰击,为研究过程中受到的砰击载荷,基于光滑粒子流体动力学(SPH)气-液两相流算法,首先通过模拟平板和楔形体两种算例模型的入水过程,并与相关文献的试验结果进行对比,验证算法的有效性。在此基础上,对返回舱的入水过程进行模拟。结果显示,两种算例模型的计算结果与相关文献试验结果吻合良好。返回舱入水速度和倾角对砰击有较大影响并且过程中存在二次砰击现象。砰击载荷随入水速度增大而增加。第一次砰击载荷峰值随倾角增大而减小,第二次砰击载荷峰值随倾角增大先增后减。结果表明,SPH气-液两相流算法能够较好地模拟返回舱入水过程。

基坑伺服钢支撑分阶段轴力设计及效果分析

目的:在软土地区进行基坑开挖时,可采用伺服钢支撑系统减小基坑围护结构的变形以及对周边环境的影响,但目前对一道伺服支撑仅有一个初始设计值,无法指导开挖过程中支撑轴力的调整,因此需要针对开挖全过程提出相应的伺服支撑轴力设计值。方法:依托南京地铁9号线白云亭路站基坑工程,分别对伺服支撑设置情况不同的全伺服段,部分伺服段断面各开挖步下的伺服支撑轴力进行分阶段优化设计。结合有限元模型与遗传算法,通过有限元模型计算某组伺服支撑设计轴力下的围护结构变形,并通过遗传算法不断生成新的轴力设计值,直至围护结构变形等参数满足设计要求;据此得到不同开挖步下较优的伺服支撑轴力设计值,实现了伺服钢支撑轴力的动态设置。建立了伺服支撑基坑的三维有限元模型,验算优化设计方案下的伺服支撑的变形控制效果及对周边环境的影响。结果及结论:分阶段优化设计得到的伺服支撑轴力可以有效控制开挖过程中围护结构的变形及周边地面沉降。

New stabilization design for planar vertical take-off and landing aircrafts

This paper presents a new stabilizing control law for a planar vertical take-off and landing aircraft.The model is first transformed into an equivalent form,and then a control law consisting of a linear term and a saturated term is given for a related subsystem,with the saturation levels being assigned as large as possible.Compared to the existing saturation scheme in which all states are restricted by saturations,the design brings about a relatively fast convergence.The effectiveness and advantage of the design are validated by numerical simulations.

超声速飞机起降阶段噪声标准分析

随着超声速飞机的发展,现有亚声速飞机起降阶段噪声规章已经无法满足其适航审定要求。结合美国联邦航空局(FAA)发布的拟议规则制定通告(NPRM)和欧洲航空安全局(EASA)发布的拟议修订通告(NPA)等文件,基于规章制定立场和思路、草案差异、技术细节以及超声速新技术等关键要素,本文对超声速飞机规章的制定进行了综述和总结。结果表明,在标准制定思路一致的前提下,美国基于工业方和技术创新的考虑,在草案中给予了足够的自由度;欧洲方面为了维持现有环境保护水平,超声速标准比起美国更加严格和细致。同时,基于分析结果形成审定要素和方法建议,为今后我国的超声速飞机起降阶段噪声标准制定和适航审定工作开展提供技术支撑。

区域土地利用与产业结构变化互动关系研究

区域土地利用变化与产业之间存在内在的联系,为了分析它们之间的内在规律,该文选择北京的海淀区、平谷区和河北省的曲周县作为研究样区,采用对比分析的方法,探讨不同经济发展阶段下典型区域土地利用变化与产业之间的互动关系。研究结果表明,在以第一产业增长为主的区域经济发展阶段,土地利用变化的驱动机制主要是农用地与环境用地间的竞争,表现为农用地比重增加,城市建设用地稳定,环境用地不断减少;在第一产业比重降低,第二、三产业比重上升阶段,土地利用变化的驱动机制是农用地内部之间以及建设用地对其它用地类型的竞争,表现为农用地内部耕地面积减少,园地面积增加,建设用地也在不断增加;而在以二、三产业增长为主的经济阶段,土地利用变化的主要驱动机制则主要表现在建设用地与环境用地之间相互竞争农用地,表现为建设用地面积增加,环境用地面积增加,而农用地面积快速下降。

不同经济发展阶段地区耕地变化的对比研究——以广西江州和江苏吴江为例

土地利用变化与经济发展密切相关，区域经济在发展过程中呈现出阶段性，耕地作为土地的精华部分．其数量和质量变化在不同经济发展阶段表现出不同的特征。江州区和吴江市经济发展具有时序差异性，是进行区域对比研究较为理想的对象。利用统计资料分析表明，江州区经济发展伴随着耕地面积不断上升，从1990年的3.8×10^4hm^2增长到2003年的5．6×10^4hm^2；吴江市则相反，耕地与经济发展呈负相关，1990年以来耕地面积持续下降，13年中共减少了1．6×10^4hm^2。以耕地标准系数表征的耕地质量表明，吴江市耕地质量提升较快，但近年有降低趋势；江州区耕地质量整体水平较低，年际变化不大，1996年～2000年间略有下降。根据江州区产业演进趋势，借鉴吴江市发展历程，可以预计，随着江州区经济发展步伐加快，建设用地需求增加，耕地压力将会加大。在经济发展过程中要注意集约用地，保护耕地，通过投入增加和技术提高，提高耕地的生产能力。