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A Methodology to Extend the Altitude Adaptability of a Turbocharged Heavy-Duty Diesel Engine
Gu Yuncheng,Ma Zetai,Zhu Sipeng,Yang Mingyang,Deng Kangyao 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.4
This research aims to propose a method to achieve the maximum altitude adaptability of turbocharged diesel engines with the optimum fuel consumption. Firstly, engine performance at different altitudes is studied by experimental method. It is found that the engine power recovery is restricted by three constraints, which are cylinder pressure, exhaust temperature and boosting pressure ratio. Following that, the influence of turbocharging system and fuel injection on the three constraints is studied via experimentally validated numerical model. A power-recovery-zone bounded by the three constraints is proposed, inside which engine power can be fully recovered. The altitude adaptability of the engine is discussed in details via this zone. Further analysis finds that the boosting pressure and the maximum pressure ratio are the key factors to the constraints. A new methodology which can achieve the maximum altitude with the optimum fuel consumption is proposed based the concept of the zone. Finally, the methodology is applied in the engine with three types of turbocharging systems to quantitatively compare their altitude adaptability. Results prove that the altitude adaptability of the engine is notably improved by adapting the proposed method, especially for the two stage turbocharging system.
( Meizhou Huang ),( Xin Zhang ),( Wenjun Yan ),( Jingjing Liu ),( Hui Wang ) 한국축산학회 2022 한국축산학회지 Vol.64 No.1
Species are facing strong selection pressures to adapt to inhospitable high-altitude environments. Yaks are a valuable species and an iconic symbol of the Qinghai-Tibet Plateau. Extensive studies of high-altitude adaptation have been conducted, but few have focused on metabolism. In the present study, we determined the differences in the serum metabolomics between yaks and the closely related species of low-altitude yellow cattle and dairy cows. We generated high-quality metabolite profiling data for 36 samples derived from the three species, and a clear separation trend was obtained between yaks and the other animals from principal component analysis. In addition, we identified a total of 63 differentially expressed metabolites among the three species. Functional analysis revealed that differentially expressed metabolites were related to the innate immune activation, oxidative stress-related metabolism, and energy metabolism in yaks, which indicates the important roles of metabolites in high-altitude adaptation in yaks. The results provide new insights into the mechanism of adaptation or acclimatization to high-altitude environments in yaks and hypoxia-related diseases in humans.
Supersonic Dual Bell Axisymmetric Minimum Length Nozzle Conception for High Propulsion Thrust
Toufik Zebbiche 한국항공우주학회 2019 International Journal of Aeronautical and Space Sc Vol.20 No.3
The aim of this work is to develop a new numerical computing program to design a new form of a dual bell axisymmetric supersonic minimum length nozzle contour, adapted to two different altitudes, usually at sea level and space, giving a supersonic uniform and parallel flow to the exit section. The first bell has a uniform and parallel sonic inlet and a low-altitude adaptation, with a reduced supersonic Mach number, while the second bell has a supersonic inlet and uniform and parallel flow and high altitude adaptation with high supersonic Mach number. The two bells are attached to an inflection point at the exit of the first bell. The passage from low altitude to high altitude is done without any mechanical activation. The purpose of this type of nozzle is the possibility of supersonic flight in two different regimes adapted into two different altitudes, under the assumption of a calorically and thermally perfect gas. This type of nozzle has an inflection point at the attachment point of the second bell to the first bell. The design is done using the method of characteristics. Solving the equations is done numerically by the predictor corrector algorithm. The validation of the results is controlled by the convergence of the critical sections ratio, calculated numerically, to that given by the theory. In this case, all the design parameters automatically converge towards the desired solution.
적응빔 형성을 이용한 다중경로 환경 내 저고도 해상표적의 고각 추적 정확도 향상
이창현(Chang-Hyun Lee),전상미(Sang-Mi Chon),박종국(Jongkuk Park),나형기(Hyung-Ki Na),김상현(Sang-Hyun Kim) 한국전자파학회 2021 한국전자파학회논문지 Vol.32 No.2
본 논문에서는 다중경로 환경에서 적응빔 형성 기법을 이용한 저고도 해상표적의 추적 정확도 향상 방법에 대해 제안하고, 이를 아날로그 빔 형성 능동위상배열(AESA: active electronically scanned array) 레이다 환경에 적용하여, 제안 방법이 반복 없는 적은 연산으로 비교적 높은 정확도의 표적 고각을 산출할 수 있음을 확인하였다. 제안 방법은 모노펄스(monopulse) 기울기 제어를 위한 기존의 적응빔 형성 제한조건에 부엽 제어 조건을 추가하고, 고각 변화 정도가 작은 저고도 해상표적의 특징을 활용하여 추적 정확도를 개선하였다. 또한 추적 정확도 향상을 위해 다양한 적응빔 형성 기법을 적용해 보고, 그 결과를 비교분석하였다. A method to improve the tracking accuracy of low-altitude sea targets is proposed using an adaptive beamforming algorithm in a multipath environment. It is confirmed that the target elevation can be estimated with relatively high accuracy without repetitive calculation using the proposed method in analog beamforming active electronically scanned array radar. The proposed method improves the tracking accuracy by adding a side-lobe suppression condition to the existing adaptive beamforming constraint for monopulse inclination control while accounting for the characteristics of the low-altitude sea target with less elevation change. In addition, various adaptive beamforming algorithms were applied to the proposed method, and the results were compared and analyzed to optimize tracking accuracy.
Byung-Cheol Min,Ji-Hyeon Hong,Eric T. Matson 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10
This research deals with an altitude controller of a quadrotor type UAV with an unknown total mass of the structure. We assume that the uncertainty results from the flight mission in which the UAV carries unknown payloads. Since the quadrotor type UAV involves both translational and rotational motions due to its inherent dynamics, it is of importance to know accurate information on the vehicles the moment of inertia and the total mass in order to guarantee the UAVs attitude and position controls. An Adaptive Robust Control (ARC) is utilized to compensate for the parametric uncertainty. Then, Lyapunov based stability analysis shows that the proposed control design guarantees asymptotic tracking error for the UAVs altitude control. Numerical simulation results which are time-based are presented to illustrate the good tracking performance of the designed control law.
Peng Zhu,Wen-han Dong,Yuhao Mao,Ri Liu 한국항공우주학회 2020 International Journal of Aeronautical and Space Sc Vol.21 No.1
This paper presents preliminary results of the application of the parameter space investigation method for the design of the L1 flight control system implemented on the ultralow-altitude airdrop process. In particular, the study has established the task performance level of airdrop mission which is chosen as the optimization objective in this paper. According to the characteristics of ultralow-altitude airdrop process, 12 optimization criteria are designated as the constraints during the multicriteria optimization. After two iterations, the task performance level of the airdrop is improved from “Moderate” to “Expected”. The results in the paper confirms the suitability of the parameter space investigation method for the multicriteria design optimization of an airdrop flight control system subject to desired control specifications. In addition, the robustness and dynamic response of the flight control system are significantly improved after optimization. Moreover, the analysis of optimization results has contributed to a deeper understanding of the relationship between L1 controller parameters and airdrop task performance.
Lateral Control for Ultra-low Altitude Airdrop Based on the L1 Adaptive Control Augmentation
Jinyong Chang,Jiahai Zhu,Ri Liu,Wen-han Dong 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.2
This paper presents a novel controller based on the L1 adaptive control to enhance the flight safety in the airdrop mission. An optimal controller produces the state feedback control signals, while a matched reference model is determined. First, we transform the system nonlinearity into the matched and unmatched uncertainty of the L1 control system. Then, leveraging the advantages of the outer loop PID controllers in the lateral deviation, we design the lateral flight control system. Simulation results reveal that the controllers present strong robustness, high adaptive gain, and suppress the undesirable high frequency dynamics.
Sameer Alsharif,Rashid A. Saeed,Yasser Albagory International Journal of Computer ScienceNetwork S 2024 International journal of computer science and netw Vol.24 No.3
This paper proposes a new communication system for e-learning applications to mitigate the negative impacts of COVID-19 where the online massive demands impact the current commu-nications systems infrastructures and capabilities. The proposed system utilizes high-altitude platforms (HAPs) for fast and efficient connectivity provision to bridge the communication in-frastructure gap in the current pandemic. The system model is investigated, and its performance is analyzed using adaptive antenna arrays to achieve high quality and high transmission data rates at the student premises. In addition, the single beam and multibeam HAP radio coverage scenarios are examined using tapered uniform concentric circular arrays to achieve feasible communication link requirements.