IMPROVED DOPPLER WARPING METHOD FOR AIRBORNE RADAR WITH NON-SIDELOOKING ARRAY

Traditional range-dependency compensation space time adaptive processing(STAP)methods usually involve aligning the clutter spectrums in a certain point to reduce the clutter non-homogeneity.A novel compensation STAP method is proposed as an improved Doppler warping(DW)method for airborne radar with non-sidelooking radar.This method facilitates DW method to bring clutter spectrum of different range gates together in the mainlobe and subsequently compensation to accomplish space angle of different range gates alignment at multiple Doppler bins.Simulation results show that the proposed method can further reduce the clutter non-homogeneity of non-sidelooking array and significantly outperform traditional algorithms with only a little increase of the computation load.

Experimental Investigation to Evaluate LiFePO4Batteries Anode and Cathode Elastic Properties under Cyclic Temperature Loading Conditions

Experimental investigations and associated methods are provided to characterize the mechanical properties of a lithium-ion battery accounting for operating temperature variation and thermal effects.Material properties for LiFePO4cathode and anode samples taken from an off-the-shelf battery are evaluated in new and fatigued(subjected to charging and discharging cycles)conditions.

Thin Film Lithium-Ionbatteries Crack Initiation Due to Thermal and Electric Effects

The transient and thermo-electric finite element analysis(FEA)of a 2Dlithium-on(Li-ion)battery is presented.The process of recharging and discharging of thin film lithium-ion(LiFePO4)battery in the presence of a transversal crack is numerically investigated.During this process significant temperature load influences the behavior of the battery and thermal fields can affect the way crack propagates into the thin film media.The simulations infer about relationship between temperature and electric field and their effect on crack propagation.A Li-ion battery model suitable for this investigation is implemented in the multi-physics software package by COMSOL Inc.,and it is extended to include the thermal and electrical effects.Results and discussion are accompanied with pertinent conclusions.

Research on Penetration Rules of LY-12cz Thin Sheet Subjected to Rod-Shaped Fragment

By establishing the finite element models and corresponding calculation methods for the target board and rod-shaped fragment, the penetration effect of the high-velocity rod-shaped fragments＇ impact on the LY- 12cz thin sheet is analyzed by analog calculation. The variation rules of the residual velocity and residual mass of fragments, chock mass and crevasse shape are obtained when the fragment penetrates target board with different incidence velocities and attack angles. Corresponding fitting computation formulas are concluded from the above calculating data. The conclusions are helpful to analyzing the destructivity of fragment and protective ability of aircraft structure. In addition, they can guide the research for battle damage mode and assessment effectively.

Acoustic Emission Characterization of Matrix Damage Initiation in Woven CFRP Composites

In this paper, an experimental investigation is performed using acoustic emission (AE) technique to study the behaviour of crack initiation and propagation of woven carbon fibre reinforced plastic (CFRP) composites under static tensile loading. Three laminates with three plies each were manufactured and tested under tensile static loading. Damage was being monitored using AE technique with instantaneous AE hits energies being used as the damage parameter. Results showed that angle ply laminates experienced crack initiations at about 50% of ultimate tensile strength whereas cross ply laminates and non-conventional angle ply laminates having one cross ply laminate experienced initiation of cracks at about a third of ultimate tensile strength. This early cracks initiation is believed to be caused by the presence of 90° plies that cannot take much load transversely.

Thermal Modelling of a Remote Sensing Satellite Panel in an Inclined Orbit

Satellites consist of different subsystems;one of them is the thermal control subsystem (TCS), which warranties the specified temperature settings of other subsystems and devices through satellite lifetime. Satellite Thermal modelling is performed by solving thermal budget equation, taking into consideration maximum and minimum external fluxes, and heat rejection from internal devices which fixed on the internal surface of the panel. To reach the optimum design for the thermal control of the panel (radiation surface areas and power of the electric heaters), the thermal analysis results should meet the design requirements, and the temperature ranges of each device or subsystem inside the satellite. Multilayer Insulation (MLI) is one of the most important passive elements of thermal control subsystem covered the satellite as a blanket consists of some layers from thin pressed Mylar or Kapton sheets. MLI is important to minimize the heat exchange between the inside (devices heat dissipation), and outside satellite (external heat fluxes). A parametric investigation is presented for an inclined satellite in Low Earth Orbit (LEO) at 650 km altitude, to study MLI covering area effect on panel thermal control design. Satellite thermal analysis is performed by Thermal desktop/SINDA FLUINT Software by decreasing and increasing MLI on the outer surfaces of the satellite, to ensure that the satellite electrical equipment temperatures maintained in the required ranges for normal operation.

Design of a large-scale model for wind tunnel test of a multiadaptive flap concept

The design and application of morphing systems are ongoing issues compelling the aviation industry.The Clean Sky-program represents the most significant aeronautical research ever launched in Europe on advanced technologies for greening next-generation aircraft.The primary purpose of the program is to develop new concepts aimed at decreasing the effects of aviation on the environment,increasing reliability,and promoting eco-friendly mobility.These ambitions are pursued through research on enabling technologies fostering noise and gas emissions reduction,mainly by improving aircraft aerodynamic performances.Within the Clean Sky framework,a multimodal morphing flap device was designed based on tight industrial requirements and tailored for large civil aircraft applications.The flap is deployed in one unique setting,and its cross section is morphed differently in take-off and landing to get the necessary extra lift for the specific flight phase.Moreover,during the cruise,the tip of the flap is deflected for load control and induced drag reduction.Before manufacturing the first flap prototype,a high-speed(Ma=0.3),large-scale test campaign(geometric scale factor 1:3)was deemed necessary to validate the performance improvements brought by this novel system at the aircraft level.On the other hand,the geometrical scaling of the flap prototype was considered impracticable due to the unscalability of the embedded mechanisms and actuators for shape transition.Therefore,a new architecture was conceived for the flap model to comply with the scaled dimensions requirements,withstand the relevant loads expected during the wind tunnel tests and emulate the shape transition capabilities of the true-scale flap.Simplified strategies were developed to effectively morph the model during wind tunnel tests while ensuring the robustness of each morphed configuration and maintaining adequate stiffness levels to prevent undesirable deviations from the intended aerodynamic shapes.Additionally,a simplified design was conceived for the flap-wing interface,allowing for quick adjustments of the flap setting and enabling load transmission paths like those arising between the full-scale flap and the wing.The design process followed for the definition of this challenging wind tunnel model has been addressed in this work,covering the definition of the conceptual layout,the numerical evaluation of the most severe loads expected during the test,and the verification of the structural layout by means of advanced finite element analyses.

Assessment of the impact of a 10-MW grid-tied solar system on the Libyan grid in terms of the power-protection system stability

The energy market in Libya is expected to face substantial changes in the next few years:electrical energy consumption will increase by 50% within the next 4 years.Therefore,there is a plan to gradually increase renewable energy sources in the power network by 2030 to 30%.Solar photovoltaic(PV)plants will play a significant role in the energy transition and the mix of energy sources in Libya.This article is a study conducted to investigate the challenges of power-flow management and power protection from integrating PV power plants into the Libyan power grid.In particular,a simulation model is built for the Kufra PV power plant(10 MW)with eight buses to assess the power network performance in terms of power quality such as voltage profile,power losses and harmonics.Furthermore,the impact of the PV plant on the short-circuit level and the power-protection system is presented under different operating conditions.The fault ride-through(FRT)is operated using standard ambient temperature and a wide range of irradiation intensity,and is verified by using the Libyan grid code.The results show that the integration of the PV plant into the grid has a significant impact on the short-circuit level and the FRT over the different fault levels and locations on the network.The initial period of the three-phase fault shows that the PV plant will be disconnected from the grid due to a decrease in the root mean square value voltages where the reactive and active power of the grid reach 938 MVAR and 261 MW,respectively.These results show that increasing the fault level will lead to an increase in injecting the active power.This work is considered the first extensive investigation into the challenges of modern power-flow management and power protection for the power network system in Libya.