Search

Measurements of Martian magnetic field, atmosphere and sampling are core missions of Martian exploration. Since the successful demonstration of the Ingenuity Helicopter, a large amount of researches have emerged on Mars rotor-craft. However, Mars rotor-crafts have short endurance and limited detection range. This paper proposes a solar-powered tilt-rotor unmanned aerial vehicle (UAV) named Archaeopteryx-I, which can perform vertical take-off and landing (VTOL) and long-endurance level flight. Its general concepts are first elucidated. Then, a multidisciplinary modeling and optimization method is proposed. Considering the harsh magnetic field and atmospheric environment of Mars, the detailed designation of mission system is carried out to further enhance the performance of Archaeopteryx-I, including avionics, energy flow, control system and electromagnetic compatibility (EMC) design. Finally, the conceptual design scheme is validated through simulation and ground testing. The results illustrate the efficaciousness and applicability of Archaeopteryx-I for Mars exploration. • A novel solar-powered tilt-rotor UAV for Martian medium granularity exploration. • The proposed conceptual design framework can deal with multidisciplinary constraints. • Avionics, energy, control, and EMC can enable the UAV to flight in high-performance. • In each cycle, the UAV can cruise on Mars at 33.24 m/s for 0.5 h and hover for 2 min. • The tilt-rotor UAV can achieve 7 to 8 complete mission cycles per Mars day. [ABSTRACT FROM AUTHOR]

According to the characteristics of the rotor system in an aero-engine and the vibrational test requirements of the aero-engine ground test, suitable vibration measurement sensors and test positions were selected. The vibration signals at the casings for the compressor and turbine of a twin-spool turbo-jet engine were collected under the states of maximum power and afterburning respectively, and the power spectrum analysis was carried out to determine the positions and causes of vibration. Furthermore, methods and preventive measures for eliminating vibration have been proposed. The results indicated that the main rotor vibration excited by mass imbalance in the twin-spool turbo-jet engine was significant. Rotor spindle misalignment or rotor radial stiffness unevenness also induced the vibration. The aerodynamic pulse vibration formed by the rotor blades of the first stage of the low pressure compressor was large, and rub induced vibration fault may occur at the turbine rotor seals. Based on the power spectrum analysis technology, the rotor system faults information including the type, position, and the degree can be quickly identified, and useful attempts and explorations have been made to reduce the vibration faults of the twin-spool turbo-jet engine. [ABSTRACT FROM AUTHOR]

A scale model experimental study is conducted addressing howl occurring during engine tests in the Propulsion Systems Laboratory (PSL) of NASA Glenn Research Center. The aim is to understand the sources of the howling noise and find possible remedies. It is shown that a jet discharged into the model of the PSL entrance duct gives rise to high levels of low frequency noise. This occurs apparently due to duct acoustic modes randomly excited by the jet. Wire-mesh screens of various mesh size and configuration as well as tabs, placed at the end of the model duct, are shown to affect the noise. Comparative effects of these configurations are studied, and some are found to alleviate the low-frequency noise significantly. Based on these results, the equivalent of a 4-mesh screen is recommended as the end treatment for the duct of the PSL facility. [ABSTRACT FROM AUTHOR]

A wireless monitoring system based on piezoelectric energy harvesting (PEH) is presented to provide fatigue data of wind turbine blades in operation. The system comprises three subsystems, each respectively providing the following functions: (i) the conversion of mechanical to electric energy by exploiting the bistable vibration of a composite beam with piezoelectric patches in post-buckling, (ii) harvesting the converted energy by means of a modified, commercial, off-the-shelf (COTS) circuit to feed a LiPo battery and (iii) the battery-powered acquisition and wireless transmission of sensory signals to the cloud to be elaborated upon by the end-user. The system was verified with ground tests under representative operation conditions, which demonstrated the fulfillment of the design requirements. The measurements indicated that the system provided 23% of the required power for fully autonomous operation when subjected to white noise base excitation of 1 g acceleration in the range of 1–20 Hz. [ABSTRACT FROM AUTHOR]

Unmanned aerial vehicles (UAVs) with an ultra-large aspect ratio and a joined-wing configuration exhibit characteristics such as minimal mass, remarkable flexibility, and a unified wing structure, thereby presenting a significant challenge in accurately assessing their dynamic behaviors in terrestrial environments. This study focuses on a specific UAV model characterized by an ultra-large aspect ratio and a joined-wing configuration, which underwent experimental scrutiny under free-free conditions, encompassing the entire aircraft. A rubber rope suspension mechanism was employed to support the UAV, and deliberate efforts were made to eliminate the additional stiffness effect, thus facilitating precise determination of the aircraft’s modal characteristics. Subsequent ground-based servoelasticity tests were conducted based on modal experimentation, and specialized filtering techniques were developed to enhance stability. Finally, an analysis of aeroservoelastic stability revealed a strong correlation between simulation and experimental results, with the UAV demonstrating high stability margins in aeroservoelasticity.

According to the characteristics of the rotor system in an aero-engine and the vibrational test requirements of the aero-engine ground test, suitable vibration measurement sensors and test positions were selected. The vibration signals at the casings for the compressor and turbine of a twin-spool turbo-jet engine were collected under the states of maximum power and afterburning respectively, and the power spectrum analysis was carried out to determine the positions and causes of vibration. Furthermore, methods and preventive measures for eliminating vibration have been proposed. The results indicated that the main rotor vibration excited by mass imbalance in the twin-spool turbo-jet engine was significant. Rotor spindle misalignment or rotor radial stiffness unevenness also induced the vibration. The aerodynamic pulse vibration formed by the rotor blades of the first stage of the low pressure compressor was large, and rub induced vibration fault may occur at the turbine rotor seals. Based on the power spectrum analysis technology, the rotor system faults information including the type, position, and the degree can be quickly identified, and useful attempts and explorations have been made to reduce the vibration faults of the twin-spool turbo-jet engine.

The nitrogen isotopic compositions of lunar soil have important implications for the sources of lunar volatiles and even the evolution of the moon. At present, the research on the lunar nitrogen isotopic compositions is mainly based on the lunar meteorites and the samples brought back by the Apollo and Luna missions. However, volatiles adsorbed on the surface of the lunar soil may be lost due to changes in temperature and pressure, as well as vibration and shock effects when the sample is returned. At the same time, in the case of low N content in the sample, since N is the main component of the earth's atmosphere, it is easily affected by the atmosphere during the analysis process. Therefore, in situ nitrogen isotopic analysis of lunar soil on orbit is necessary to avoid the problems mentioned above and is one of the primary science goals for the Lunar Soil Volatile Measuring instrument on Chang'e-7 spacecraft. After the nitrogen purification procedure, the volatiles in lunar soil that are released through single-step or stepped heating techniques diffuse to the quadrupole mass spectrometer to obtain the N contents and isotopic compositions of the lunar soil. This paper introduces the ground test for N isotopic analysis of lunar soil in orbit according to the Lunar Soil Volatile Measuring Instrument. After long-term repeated measurements, the background and CO-corrected Air-STD 14N/15N ratio is 268.986 ± 4.310 (1SD, n = 35), and the overall reproducibility of measurements is 1.6%. The accuracy of N isotopic compositions is calculated to be better than 5%, which can distinguish different sources of N components in lunar soil. [ABSTRACT FROM AUTHOR]

Numerical simulation and related experimental research on supersonic aerodynamic heating are important contents in the development of hypersonic vehicles. The boundary layer flow and heat transfer process in the supersonic aerodynamic heating phenomenon are analyzed, and the effects of the engineering model, gas model, turbulence model, grid scale, calculation scheme, and boundary conditions in aerodynamic heating simulation on the numerical simulation are discussed from the physical point of view. This paper introduces the test equipments commonly used in the research of aerodynamic heating, such as oxygebacetylene flame ablation, radiation heater and high enthalpy wind tunnel, and their advantages and disadvantages, also discusses the similar parameters in the ground simulation test, and points out the reasons for the over high heat flow of the cold wall.

Aeroservoelastic ground simulation test is a new aeroelastic ground test technology developed in recent years. One of the key problems is the condensation of unsteady aerodynamic forces, that is, the distributed aerodynamic loads on flight vehicles are condensed into a few concentrated loads. The traditional condensation method deals with the distributed force with a simple force and moment balance criterion, or takes the support reaction forces as the condensation forces by solving the statically indeterminate problem. These methods have some disadvantages. In this paper, an equivalent condensation method based on one-dimensional spline interpolation is proposed for the distributed loads of slender vehicles, and the key mode similarity criterion is used to optimize the location of condensation points, so as to achieve the effects that the dynamic responses of slender body under the concentrated loads of condensation points are the closest to that under the distributed loads. The accuracy of the proposed condensation method is verified by two examples of simple supported beam and cantilever beam, and the condensation method is applied to the aeroservoelastic ground simulation of a slender missile. Numerical simulation shows that the unsteady aerodynamic force of the missile can be condensed into real-time concentrated force quickly and accurately by using this method, which meets the accuracy and rapidity requirements of aeroservoelastic ground simulation test.

In the final approach stage of rendezvous and docking of a spacecraft, the pose parameters of the target spacecraft need to meet docking or berthing capture conditions. Visible light visual measurement systems are increasingly employed in spacecraft ground tests to extract the geometric features of spacecraft to calculate and verify the accuracy of pose parameters. Most current feature-segmentation algorithms are unable to break through the scale transformation problem of spacecraft movement and the noise interference of multi-layer insulation materials in imaging. To overcome these challenges, we propose a novel feature segmentation algorithm based on the framework of deep convolutional neural networks. Firstly, a full convolution model of the encoding-decoding structure is constructed based on data for the ground test. A feature concatenation module is applied and combined with a network backbone to improve the segmentation performance. Then, a comprehensive loss function is presented and optimized by the pose characteristics of the spacecraft in the approach phase. Furthermore, a specific spacecraft simulation dataset to train and test our segmentation model is built through data augmentation. The experimental results verify that the proposed method achieves accurate segmentation of spacecraft of different scales, suppresses the interference caused by multilayer insulation material, and has strong robustness against motion ambiguity. The pixel accuracy of our proposed method reaches 96.5%, and the mean intersection over union is 93.0%. [ABSTRACT FROM AUTHOR]

A wireless monitoring system based on piezoelectric energy harvesting (PEH) is presented to provide fatigue data of wind turbine blades in operation. The system comprises three subsystems, each respectively providing the following functions: (i) the conversion of mechanical to electric energy by exploiting the bistable vibration of a composite beam with piezoelectric patches in post-buckling, (ii) harvesting the converted energy by means of a modified, commercial, off-the-shelf (COTS) circuit to feed a LiPo battery and (iii) the battery-powered acquisition and wireless transmission of sensory signals to the cloud to be elaborated upon by the end-user. The system was verified with ground tests under representative operation conditions, which demonstrated the fulfillment of the design requirements. The measurements indicated that the system provided 23% of the required power for fully autonomous operation when subjected to white noise base excitation of 1 g acceleration in the range of 1–20 Hz.

Copyright of Aero Weaponry is the property of Aero Weaponry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Aero Weaponry is the property of Aero Weaponry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Oscillation fault is a kind of aircraft fault which has a great influence on flight safety, aircraft structure and system control. This paper analyzes the causes and influencing factors of aircraft oscillation fault, and defines the design path and monitoring level of oscillation fault monitoring, proposes a design and verification method of oscillation fault monitor, and verifies its feasibility by applying it to a certain type of flight control system. This result has a good guiding role for the design and test verification of the aircraft flight control system oscillation fault monitor, can support the flight control system oscillation fault test, and verify the compliance of the oscillation fault monitor with the design requirements and corresponding airworthiness terms. [ABSTRACT FROM AUTHOR]

The nitrogen isotopic compositions of lunar soil have important implications for the sources of lunar volatiles and even the evolution of the moon. At present, the research on the lunar nitrogen isotopic compositions is mainly based on the lunar meteorites and the samples brought back by the Apollo and Luna missions. However, volatiles adsorbed on the surface of the lunar soil may be lost due to changes in temperature and pressure, as well as vibration and shock effects when the sample is returned. At the same time, in the case of low N content in the sample, since N is the main component of the earth’s atmosphere, it is easily affected by the atmosphere during the analysis process. Therefore, in situ nitrogen isotopic analysis of lunar soil on orbit is necessary to avoid the problems mentioned above and is one of the primary science goals for the Lunar Soil Volatile Measuring instrument on Chang’e-7 spacecraft. After the nitrogen purification procedure, the volatiles in lunar soil that are released through single-step or stepped heating techniques diffuse to the quadrupole mass spectrometer to obtain the N contents and isotopic compositions of the lunar soil. This paper introduces the ground test for N isotopic analysis of lunar soil in orbit according to the Lunar Soil Volatile Measuring Instrument. After long-term repeated measurements, the background and CO-corrected Air-STD 14N/15N ratio is 268.986 ± 4.310 (1SD, n = 35), and the overall reproducibility of measurements is 1.6%. The accuracy of N isotopic compositions is calculated to be better than 5%, which can distinguish different sources of N components in lunar soil.

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the final approach stage of rendezvous and docking of a spacecraft, the pose parameters of the target spacecraft need to meet docking or berthing capture conditions. Visible light visual measurement systems are increasingly employed in spacecraft ground tests to extract the geometric features of spacecraft to calculate and verify the accuracy of pose parameters. Most current feature-segmentation algorithms are unable to break through the scale transformation problem of spacecraft movement and the noise interference of multi-layer insulation materials in imaging. To overcome these challenges, we propose a novel feature segmentation algorithm based on the framework of deep convolutional neural networks. Firstly, a full convolution model of the encoding-decoding structure is constructed based on data for the ground test. A feature concatenation module is applied and combined with a network backbone to improve the segmentation performance. Then, a comprehensive loss function is presented and optimized by the pose characteristics of the spacecraft in the approach phase. Furthermore, a specific spacecraft simulation dataset to train and test our segmentation model is built through data augmentation. The experimental results verify that the proposed method achieves accurate segmentation of spacecraft of different scales, suppresses the interference caused by multilayer insulation material, and has strong robustness against motion ambiguity. The pixel accuracy of our proposed method reaches 96.5%, and the mean intersection over union is 93.0%.

The deep oil and gas formation has strong abrasiveness, high hardness and poor drillability, which are the main causes of low rate of penetration (ROP). Percussive drilling technique can greatly improve the ROP of hard formation. In order to improve the impact force of the drilling tool, a new type of drilling tool with impellers as pulse source and Helmholtz pressurized cavity was designed. Through the ground test, the pulse impact performance of the tool was compared, and the effects of different working parameters (flow rate) and the structural parameters of Helmholtz pressurized cavity (cavity diameter, cavity length and inner wall collision angle) on the output frequency, pressure amplitude and pressure loss of the tool were studied. Finally, the parameters of the enhanced pulse jet generating mechanism were optimized. The results show that the enhanced pulse impact speed-up tool can increase pulse amplitude and adjust the pulse frequency from 4 Hz to 12.5 Hz, which is suitable for drilling in hard formations. With the increase of cavity length and diameter, the impact frequency decreases continuously. When the inlet diameter of Helmholtz pressurized cavity is 40 mm, the cavity diameter is 80 mm, the cavity length is 70 mm and the inner wall collision angle is 60°, the pulse jet output characteristics reach the best with the increase of displacement. It provides a new idea for the development of percussion drilling tools. [ABSTRACT FROM AUTHOR]

A new type of flexible web with a spatial symmetry structure is proposed to address the interception and acquisition of UAVs. It is different from the existing flexible web structure. According to the mechanical characteristics of the flexible web, the dynamic analysis model of the flexible web is established through theoretical deduction. Through finite element simulation calculation, the flexible webs of three different spatial symmetric structures are compared and analyzed. The internal force and air attitude of the three flexible webs are discussed. Among them, the new flexible web has a lag time of 0.162 s and a flight height of 11.624 m. The above simulation parameters are better than those of the other two symmetrical structures. It was proved that the new spatial symmetric flexible web has good traction and deployment performance. In addition, a ground verification test is designed and carried out. The web attitude and flight altitude parameters are compared with the simulation and test results. It is found that the simulation and experimental process of the new symmetric structure web are in good agreement, the synchronization of attitude change is good, and the flight altitude error of the two is controlled at about 5%. The feasibility and effectiveness of this method are proven and it can provide a reference for the research of flexible interception and acquisition of UAVs. [ABSTRACT FROM AUTHOR]

Considering the vibration generated by a propeller-driven UAV or encountering gust, the propeller will perform a very complex follower motion. A pitch and rotating coupled motion is proposed in the present work that can take more complex unsteady performance of follower force than a regular fixed-point rotating motion. In order to evaluate the unsteady follower force and conduct parametric study, an extensive ground test bench was designed for this purpose where the whole test system was driven by a linear servo actuator and the follower force was measured by a 6-component balance. For CFD simulation, coupled motion in particular needs detailed unsteady aerodynamic model; therefore, a high-fidelity CFD-based study integrated with the overset mesh method was complemented to solve the unsteady fluid of varying conditions. The results suggest that a significant influence on unsteady follower force is observed, and the mean value of in-plane force does not equal to zero during the coupled motion process. Compared with the regular fixed-point rotation of propeller, the fluctuation frequency of follower force in present work couples the rotation and pitch motion frequencies. In addition, the oscillation amplitude of out-plane force and torque is positively related with the pitch frequency, pitch amplitude, and relative length from leading edge of wing to the rotation center. For example, the oscillation amplitude of 1-blade’s out-plane force and torque increases by 57.122% and 66.542% for the 5 Hz-5 deg case compared with the 5 Hz-3 deg case, respectively. However, the torque is not sensitive to frequency of pitch motion. The generally excellent agreement evident between the ground test and numerical simulation results is important as guidance for our future investigation on “dynamic” aerodynamic performance of a propeller-driven UAV.

Copyright of Ordnance Industry Automation is the property of Editorial Board for Ordnance Industry Automation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As part of China's first Mars exploration mission 'Tianwen-1', the Zhurong rover has successfully touched down on the surface of southern Utopia Planitia on May 15th 2021 and has been conducting surface operations for several months. A multispectral camera (MSCam), as an important payload onboard the Zhurong rover, aims to acquire multispectral images to investigate the morphological characteristics and mineralogic properties of the Martian surface. In this study, a detailed optimization design for the MSCam was carried out to achieve the abovementioned scientific objectives. The MSCam can perform multispectral imaging without chromatic aberration by utilizing eight narrow bandwidth filters made of glass of different thicknesses. Clear images of observation targets at different distances can be obtained by utilizing the six focal plane compensation lenses of varying thicknesses through the rotation of wheels. Calibration experiments, key specification tests and ground verification tests were also conducted in this study. Our results show that the pixel resolution of the MSCam can reach 0.146 mrad, the system static modulation transfer function (MTF) of the MSCam is better than 0.25@525 nm, and the signal-to-noise ratio (SNR) is higher than 40 dB, all of which allow clear imaging and accurate multispectral data acquisition of the targets. The high-resolution images obtained by the MSCam will provide detailed geological context for the data interpretation of other payloads on the rover, such as the Mars surface composition detector (MarSCoDe). The mineralogy information of the targets (e.g., fresh rock, dune) indicated by the MSCam multispectral data will also help to constrain the surface material composition of Mars. [ABSTRACT FROM AUTHOR]

Solar sails, characterized by passive propulsion, have attracted an increasing attention of researchers, which has important value in the field of deep space exploration. SIASAIL-I is an on-orbit verification mission for solar sails based on a 6U cubesat, designed and produced by Shenyang Institute of Automation, Chinese Academy of Sciences (SIA, CAS). SIASAIL-I deployment mechanism is composed by two-stage deployment system, which can achieve direction transformation, stretching and membrane deploying in the narrow space of the cubesat. SIASAIL-I only takes up within 0.5U (48 mm × 90 mm × 95 mm) space and the total mass is within 1kg. SIASAIL-I was successfully launched from the Xiaoxiang-1 07 satellite on August 31, 2019, and successfully deployed a 0.78 m × 0.78 m sail in low earth orbit in December. This paper introduces the design process of SIASAIL-I system, including deployment mechanism, a series of ground experiments, and an de-orbit mission analysis, which aims to provide some engineering experience for the development of solar sails. • Development of the 0.5U solar sail, SIASAIL-I system. • Ground testing of SIASAIL-I. • A de-orbit strategy is analyzed for SIASAIL-I. • SIASAIL-I was deployed on-orbit successfully. [ABSTRACT FROM AUTHOR]

The aerodynamic performances of a ducted propeller system applied in a manned vertical takeoff and landing aircraft considering the ground effect are investigated. Based on the ground test and CFD simulation combined with sliding mesh technique, the thrust and power characteristics of the ducted propeller under different heights between the duct and ground are compared and analyzed, and the influence mechanism of the ground effect on the aerodynamic performance of the ducted propeller is detailed analyzed based on the CFD simulation results. The test and simulation results show that, the ground near the ducted propeller leads to a high-pressure zone to block the jet flow through the outlet of the duct, while an upward rebounded flow with the vortex rings is also generated to affect the aerodynamic forces and powers of both the duct and propeller. As the influence of the high-pressure zone, the thrust of the propeller increases. However, the thrust of the duct decreases when the rebounded flow is inhaled again into the duct. With the increase of the heights between the ground and the ducted propeller, the ground effect is weakened, and the power of the system recovers more quickly than the thrust. In general, the ground effect seriously affect the aerodynamic efficiency of the ducted propeller in near ground hover state, which should be mainly considered in the process of aerodynamic and conceptual design.

In order to make the space flexible webs system have more effective capability of capture, this paper designs a new space debris removal device, which consists of bionic flexible webs, central hub, magnetic mass and rotating mechanism. According to the principle of bionics and institutional design method, which based on the research of spider web structure and capture performance analysis. Firstly, the image processing system of spider web is established, and the spider web image is digitally processed to extract the structure shape of the spider web. According to the structure of spider web, a simplified cobweb-like flexible structure is proposed and a “cobweb-like” flexible capture device is designed. Then, the model of flexible web is established based on the finite element method, and the capture effect is compared with the traditional quadrilateral webs. Finally, a ground experiment system of “cobweb-like” flexible capture device is designed, and a verification experiment of the capture effect of the flexible webs is carried out. The results show that the bionic design scheme in this paper can fully meet the design requirements for the flexible webs capture system in space and the research provides theoretical and experimental references for the engineering realization of the space flexible webs capture system.

A new type of flexible web with a spatial symmetry structure is proposed to address the interception and acquisition of UAVs. It is different from the existing flexible web structure. According to the mechanical characteristics of the flexible web, the dynamic analysis model of the flexible web is established through theoretical deduction. Through finite element simulation calculation, the flexible webs of three different spatial symmetric structures are compared and analyzed. The internal force and air attitude of the three flexible webs are discussed. Among them, the new flexible web has a lag time of 0.162 s and a flight height of 11.624 m. The above simulation parameters are better than those of the other two symmetrical structures. It was proved that the new spatial symmetric flexible web has good traction and deployment performance. In addition, a ground verification test is designed and carried out. The web attitude and flight altitude parameters are compared with the simulation and test results. It is found that the simulation and experimental process of the new symmetric structure web are in good agreement, the synchronization of attitude change is good, and the flight altitude error of the two is controlled at about 5%. The feasibility and effectiveness of this method are proven and it can provide a reference for the research of flexible interception and acquisition of UAVs.

When using suspension method to simulate the microgravity environment, part of the hanger forces are used to offset the influence of gravitational field on the deployable structure, while the other part produces additional forces that affect the driving forces and precision of the deployable structure. In order to reduce the adverse effect of hanger forces, and avoid the construction of complex finite element theoretical model, an optimization method based on adaptive genetic algorithm with MATLAB and Nastran co-simulation is proposed. Then, the hanger forces are optimized, and the deployable structure deformation has been reduced 49%. It suggests that the adverse effect of hanger forces has been effectively reduced and the proposed optimization method works well. [ABSTRACT FROM AUTHOR]

A 105‐m, 13‐MW two‐bladed downwind Segmented Ultralight Morphing Rotor (SUMR‐13) blade was gravo‐aeroelastically scaled by 20% to a 20.87‐m‐long demonstrator blade and confirmed through structural ground testing. The subscale model was achieved through geometric scaling and by aeroelastic scaling principles based on operational flapwise deflections combined with rotational and structural frequencies while retaining the turbine tip‐speed ratio. In particular, the subscale demonstrator was designed to replicate, as closely as possible, the nondimensional geometry, the ratio of centrifugal to gravitational moments, the tip‐speed ratio, and the nondimensional rotation rate. The intent for this demonstrator was to achieve the same nondimensional flapwise blade deflections and dynamics of the full‐scale 13‐MW rotor. The manufactured SUMR‐D blade resulted in less than half of the mass of the conventional two‐bladed Controls Advanced Research Turbine (CART2) rotor blade based on scaling and a lower power rating, though with some differences in mass and stiffness from the ideal scaled‐down design to meet safety requirements at the test site. To achieve proper scaling, operational pitch control set points were altered to account for the differences by evaluating simulated operation of both the SUMR‐13 and SUMR‐D rotors. Structural testing of the SUMR‐D blade investigated the response to well‐defined flapwise loads and indicated that the subscale blade had the appropriate elastic properties needed for both scaling and for safe operational field testing. [ABSTRACT FROM AUTHOR]

In general fast-growing tree species harvested at a young age has substantial amount of sapwood. It also contains juvenile wood, which has undesirable inferior physical and mechanical properties. Having sapwood and juvenile wood in the trees makes them very susceptible to be attacked by biological deterioration specifically termites in a tropical environment. The main objective of this study was to investigate the termite resistance of four fast-growing Indonesian wood species treated with furfuryl alcohol and imidacloprid. Wood specimens from sengon (Falcataria moluccana), jabon (Anthocephalus cadamba), mangium (Acacia mangium), and pine (Pinus merkusii) were impregnated with furfuryl alcohol, using tartaric acid and heat as well as treated with imidacloprid for the polymerization process. All of the specimens were exposed to environmental conditions in the field for three months. Based on the findings in this work, the untreated control samples had higher weight loss values and lower protection levels than those of imidacloprid-treated and furfurylated samples of all four species. It appears that furfurylation and imidacloprid treatment of such fast-growing species had a significant impact regarding their resistance against termite so that their service life can be extended during their utilization. [ABSTRACT FROM AUTHOR]

This work deals with the lunar sample return project, which requires lunar samples to be returned back to the ground without contamination. In this paper, a knife edge indium seal is proposed as a primary sealing form, where indium–silver alloy is welded into an annular groove of a cylindrical container firstly and then extruded by an annular knife edge of a cylindrical lid. The analysis of the leakage and sealing reliability of knife edge indium seal is the main aim of this paper. Firstly, the pretreatment of knife edge indium seal is discussed. Key techniques on indium welding are studied to evaluate its sealing reliability, with the tensile strength and welding void ratio mainly being discussed. Secondly, by means of "Roth" leakage theory, mathematical models on the leak rate for knife edge seal are established. By means of the finite element analysis, the knife edge geometry is optimized with minimum pressing force required. The results justify that the knife edge seal demands much lower pressing force to achieve a considerable sealing performance, which is suitable for low-powered operation. Finally, the ground tests are carried out to evaluate the feasibility of the indium welding and to measure the leak rate of the knife edge indium seal. Experimental results demonstrate the indium welding onto the stainless steel container is feasible, and the leak rate at room temperature is 3.0 × 10−10 Pa·m3/s, which is much lower than the rubber O-type ring seal. The knife edge indium seal is suitable for lunar sample return devices. [ABSTRACT FROM AUTHOR]

A single-body typed TDLAS sensor was developed, and its robustness and performance were experimentally evaluated under harsh thermal and mechanical environments which could be formed in scramjet intake. To confirm integrity and operability of the TDLAS sensor in the harsh thermal environments, high-thermal gradient, long-duration heating, and aero-heating tests were conducted. The high-thermal gradient, long-duration heating, and aero-heating tests were performed using high-temperature torch, furnace, and supersonic wind tunnel, respectively. In addition, vibration, mechanical shock, and acceleration tests were performed to analyze the durability and operating performance of the TDLAS sensor in the harsh mechanical environments. The vibration/mechanical shock, and acceleration tests were carried out using shaker and centrifuge, respectively. The TDLAS sensor did not experience any damage and had a stability of signal measurement under these severe thermal and mechanical environments. The experimental test results showed that the single-body TDLAS sensor in this paper could be used in the extreme thermal and mechanical conditions which could be formed in the scramjet intake. [ABSTRACT FROM AUTHOR]

In general fast-growing tree species harvested at a young age has substantial amount of sapwood. It also contains juvenile wood, which has undesirable inferior physical and mechanical properties. Having sapwood and juvenile wood in the trees makes them very susceptible to be attacked by biological deterioration specifically termites in a tropical environment. The main objective of this study was to investigate the termite resistance of four fast-growing Indonesian wood species treated with furfuryl alcohol and imidacloprid. Wood specimens from sengon (Falcataria moluccana), jabon (Anthocephalus cadamba), mangium (Acacia mangium), and pine (Pinus merkusii) were impregnated with furfuryl alcohol, using tartaric acid and heat as well as treated with imidacloprid for the polymerization process. All of the specimens were exposed to environmental conditions in the field for three months. Based on the findings in this work, the untreated control samples had higher weight loss values and lower protection levels than those of imidacloprid-treated and furfurylated samples of all four species. It appears that furfurylation and imidacloprid treatment of such fast-growing species had a significant impact regarding their resistance against termite so that their service life can be extended during their utilization.

Copyright of Computer Measurement & Control is the property of Magazine Agency of Computer Measurement & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study reports the combustion oscillation features in a three-dimensional (3D) rocket-based combined-cycle (RBCC) engine combustor under flight Mach number ( M flight ) 3.0 conditions both experimentally and numerically. Experiment is performed on a direct-connect ground test facility, which measures the wall pressure along the flow-path. High-speed imaging of the flame luminosity and schlieren is carried out at exit of the primary rocket. Compressible reactive large eddy simulation (LES) with reduced chemical kinetics of a surrogate model for kerosene is performed to further understand the combustion oscillation mechanisms in the combustor. LES results are validated with experimental data by the time-averaged and root mean square (RMS) pressure values, and show acceptable agreement. Effects of the primary rocket jet on pressure oscillation in the combustor are analyzed. Relation of the high speed rocket jet oscillation, which is thought to among the most probable sources of combustion oscillation, with the RBCC combustor is recognized. Results reveal that the unsteady over-expanded rocket jet has significant impacts on the combustion oscillation feature of the RBCC combustor, which is different from a thermo-acoustics type oscillation. The rocket jet/air inflow physical interactions under different rocket jet expansion degrees are experimentally studied. [ABSTRACT FROM AUTHOR]

GyroWheel is an innovative device that combines the actuating capabilities of a control moment gyro with the rate sensing capabilities of a tuned rotor gyro by using a spinning flex-gimbal system. However, in the process of the ground test, the existence of aerodynamic disturbance is inevitable, which hinders the improvement of the specification performance and control accuracy. A vacuum tank test is a possible candidate but is sometimes unrealistic due to the substantial increase in costs and complexity involved. In this paper, the aerodynamic drag problem with respect to the 3-DOF flex-gimbal GyroWheel system is investigated by simulation analysis and experimental verification. Concretely, the angular momentum envelope property of the spinning rotor system is studied and its integral dynamical model is deduced based on the physical configuration of the GyroWheel system with an appropriately defined coordinate system. In the sequel, the fluid numerical model is established and the model geometries are checked with FLUENT software. According to the diversity and time-varying properties of the rotor motions in three-dimensions, the airflow field around the GyroWheel rotor is analyzed by simulation with respect to its varying angular velocity and tilt angle. The IPC-based experimental platform is introduced, and the properties of aerodynamic drag in the ground test condition are obtained through comparing the simulation with experimental results. [ABSTRACT FROM AUTHOR]

Focusing on partial nucleate pool boiling at low heat flux, SOBER-SJ10, one of 27 experiments of the program SJ-10, has been proposed to study local convection and heat transfer around an isolated growing vapor bubble during nucleate pool boiling on a well characterized flat surface in microgravity. An integrated micro heater has been developed. By using a local pulse overheating method in the experimental mode of single bubble boiling, a bubble nucleus can be excited with accurate spatial and temporal positioning on the top-side of a quartz glass substrate with a thickness of 2 mm and an effective heating area of 4.5 mm in diameter, and then grows under an approximate constant heat input provided by the main heater on the back-side of the substrate. Ten thin film micro-RTDs are used for local temperature measurements on the heating surface underneath the growing bubble. Normal pool boiling experiments can also be carried out with step-by-step increase of heating voltage. A series of ground test of the flight module of SOBER-SJ10 have been conducted. Good agreement of the measured data of single phase natural convection with the common-used empirical correlation warrants reasonable confidence in the data. It is found that the values of the incipience superheat of pool boiling at different subcooling are consistent with each others, verifying that the influence of subcooling on boiling incipience can be neglected. Pool boiling curves are also obtained, which shows great influence of subcooling on heat transfer of partial nucleate pool boiling, particularly in lower heat flux. [ABSTRACT FROM AUTHOR]