A haptic illusion created by gravity

Human dexterity requires very fine and efficient control of fingertip forces, which relies on the integration of cutaneous and proprioceptive feedback. Here, we examined the influence of gravity on isometric force control. We trained participants to reproduce isometric vertical forces on a dynamometer held between the thumb and the index finger in normal gravity and tested them during parabolic flight creating phases of microgravity and hypergravity, thereby strongly influencing the motor commands and the proprioceptive feedback. We found that gravity creates the illusion that upward forces are larger than downward forces of the same magnitude. The illusion increased under hypergravity and was abolished under microgravity. Gravity also affected the control of the grip force employed to secure the grasp. These findings suggest that gravity biases the haptic estimation of forces, which has implications for the design of haptic devices to be used during flight or space activities.

Active disturbance rejection control of drag-free satellites considering the effect of micro-propulsion noise

The space gravitational wave detection mission requires a super "static and precise" scientific experiment environment. In order to solve the non-conservative force disturbance variation and the actuator noise and measurement noise, this paper designs a drag-free control scheme based on active disturbance rejection control (ADRC) framework to achieve the high-precision index. According to the ultra-high accuracy, low bandwidth limitation, and robustness requirements of drag-free satellite, the H_∞ controller satisfying the robustness constraint is designed as an active disturbance rejection feedback controller to achieve the high-precision index. Meanwhile, the non-conservative force disturbance with a wide range of variations is estimated and feedforward compensated by an extended state observer to improve the system robustness. Simulation results show that the control system can achieve the relative displacement of 2 nm/Hznm/Hz^1/2 for the drag-free satellite platform and the residual acceleration of 1 × 10^-15 m/sm/s²/Hz^1/2 for the test mass.

Increasing the robustness and crack resistivity of high-performance carbon fiber composites for space applications

The endeavors to develop manufacturing methods that can enhance polymer and composite structures in spacecraft have led to much research and innovation over many decades. However, the thermal stability, intrinsic material stress, and anisotropic substrate properties pose significant challenges and inhibit the use of previously proposed solutions under extreme space environment. Here, we overcome these issues by developing a custom-designed, plasma-enhanced cross-linked poly(p-xylylene):diamond-like carbon superlattice material that enables enhanced mechanical coupling with the soft polymeric and composite materials, which in turn can be applied to large 3D engineering structures. The superlattice structure developed forms an integral part with the substrate and results in a space qualifiable carbon-fiber-reinforced polymer featuring 10-20 times greater resistance to cracking without affecting the stiffness of dimensionally stable structures. This innovation paves the way for the next generation of advanced ultra-stable composites for upcoming optical and radar instrument space programs and advanced engineering applications.

A comprehensive review of energy sources for unmanned aerial vehicles, their shortfalls and opportunities for improvements

Unmanned Aerial Vehicles were first introduced almost 40 years ago and their applications have increased and diversified substantially since then, in both commercial and private use. One of the UAVs main issues when it comes to mobility is that the power sources available are inadequate, this highlights an area for improvement as the interest in drones is on the increase. There exist many different types of power supplies applied to UAVs, however each has their own limitations and strengths that pertain to weight contributions, charging and discharging times, size, payload capabilities, energy density and power density. The aim of this paper is to review the main power sources available for UAVs, determine their shortfalls, compare the power sources with each other and offer suggestions as to how they can be improved – hence identifying where the gap lies for developing better alternative power sources.

Debris cloud of India anti-satellite test to Microsat-R satellite

Understanding the motion of debris cloud produced by the anti-satellite test can help us to know the danger of these tests. This study presents the orbit status of 57 fragments observed by the CelesTrak and presented in the NORAD Two-Line Element Sets of India Anti-Satellite Test. There are 10 of these observed fragments have altitudes of the apogee larger than 1000.0km, the maximum one is 1725.7km. We also numerical calculated the number of debris, the results show that the number of debris with the diameter larger than 0.2m is 14, the number of debris with the diameter larger than 0.01m is 6587, and the number of debris with the diameter larger than 0.001m is 7.22×10⁵. The results of the secondary collision of the debris will produced more fragments in the space. The life time of the fragments depends on the initial orbit parameters and the sizes of the debris.

Towards bio-inspired robots for underground and surface exploration in planetary environments: An overview and novel developments inspired in sand-swimmers

Dessert organisms like sandfish lizards (SLs) bend and generate thrust in granular mediums to scape heat and hunt for prey [1]. Further, SLs seems to have striking capabilities to swim in undulatory form keeping the same wavelength even in terrains with different volumetric densities, hence behaving as rigid bodies. This paper tries to recommend new research directions for planetary robotics, adapting principles of sand swimmers for improving robustness of surface exploration robots. First, we summarize previous efforts on bio-inspired hardware developed for granular terrains and accessing complex geological features. Later, a rigid wheel design has been proposed to imitate SLs locomotion capabilities. In order to derive the force models to predict performance of such bio-inspired mobility system, different approaches as RFT (Resistive Force Theory) and analytical terramechanics are introduced. Even in typical wheeled robots the slip and sinkage increase with time, the new design intends to imitate traversability capabilities of SLs, that seem to keep the same slip while displacing at subsurface levels.

The efficiency of using a tailored inventory management system in the military aviation industry

Introduction

Military aviation inventory management systems are a vital tool for air forces to reduce operating costs whilst improving fleet readiness, aircraft serviceability, and availability, and the safety measurements of the country.

Objective

This paper aims to establish a local, affordable, high quality, reliable, and adaptive inventory management system which manages and improves inventory in the military aviation industry (Air forces). The aim of the new system is to improve aircraft fleet serviceability, reliability, and readiness in order to enhance the operational status and level of readiness at the least possible costs.

Methods

This study designs, proposes, and implements a highly reliable customized Microsoft Access software as a powerful, simple, user-friendly. Affordable software that supports the on-time availability of the air force inventory of spare parts. The system will have full capability of integrating maintenance management systems (M.M.S.) and will address aircraft inventory challenges.

Results

The proposed system provides high-quality reports that improve supply chain management and processes that help collate maintenance, supply chain, and logistics information that reduces stock to the minimum. This will result in improved components, increased serviceability, availability, and reliability, decreased costs, and decreased Aircraft on Ground (A.O.G.).

Production of graphene nanoplate/polyetheretherketone composites by semi-industrial melt-compounding

Current studies on nanocomposites have focused on their multifunctional properties and their industrial production. In this work, polyetheretherketone (PEEK)/graphene nanoplate (GNP) composites were produced by a direct semi-industrial process. Different percentages of untreated GNP (1, 5, and 10 wt.%) were added to PEEK by employing melt-compounding followed by injection-moulding. Despite the semi-industrial approach used, the modulus, strength, and Poisson coefficient of the nanocomposites (1 and 5 wt.%) were not significantly affected by the addition of GNP. However, there was a slight decrease in the strength at 10 wt.% GNP. Our study also shows that the thermal conductivities of PEEK/GNP composites are up to 2.5 times higher than that of pure PEEK.

Thermal picks for anchoring on icy moons

Europa, Enceladus, and other icy moons are exciting science targets, but our capabilities to adequately explore these planetary bodies needs to be developed. Gripping the surface ice may aid the stability and mobility of surface landers and mobile explorers that are sent to the surface of an icy moon. This paper presents an approach to anchoring into the surface of an icy moon using a heated pick.

The proposed thermodynamic approach contrasts with the traditional mechanical approach to inserting terrestrial ice anchors. This thermodynamic approach maintains the ice structure to provide a reliable hold. The low temperatures and lack of a significant atmosphere on most of the icy moons cause surface conditions to stay below the triple point of water, the primary constituent of the surface ice for both Europa and Enceladus. Under these conditions the surface water ice will sublimate when sufficiently heated. The thermal pick concept presented in this paper is used to study the nature of the sublimation that results from forced insertion of an object into ice, which could then be used as an anchor for stability and mobility.

While the surfaces of the icy moons are composed primarily of water ice at cryogenic and vacuum conditions, the nature of a sublimation process can be more readily examined with frozen CO2, which sublimates under atmospheric conditions. This paper explores the physical phenomena and thermodynamic design considerations of a heated device that uses a sublimation based insertion into frozen CO2 under atmospheric conditions. This approach was found to allow for proper insertion of thermal picks with energetic efficiencies of up to 90%.

Ensuring efficiency and reliability of equipment with optimization of integrated tests

The paper suggests a method for optimization of the process of integrated tests for complex technical equipment of automotive, aviation, and rocket systems based on an analysis of efficiency dynamics models. The method makes it possible to determine scopes of ground tests for complex technical equipment, which are minimally required to start field tests under the necessity to combine ground and field development. Exponential models of complex systems' development are used as efficiency dynamics models for the whole testing process as well as efficiency dynamics models at various levels of the hierarchy of tests. The paper addresses an optimization task when the structure of tests at each level of the hierarchy is specified, i.e. efficiency dynamics models are determined for each level. The authors determine optimal points of transition from one level of tests to another, considering the random nature of efficiency dynamics parameters. A method for optimization using determination of the optimal scope of field tests is given.

Protein structural changes on a CubeSat under rocket acceleration profile

Catalyzing life-sustaining reactions, proteins are composed by 20 different amino acids that fold into a compact yet flexible three-dimensional architecture, which dictates what their function(s) might be. Determining the spatial arrangement of the atoms, the protein's 3D structure, enables key advances in fundamental and applied research. Protein crystallization is a powerful technique to achieve this. Unlike Earth's crystallization experiments, biomolecular crystallization in space in the absence of gravitational force is actively sought to improve crystal growth techniques. However, the effects of changing gravitational vectors on a protein solution reaching supersaturation remain largely unknown. Here, we have developed a low-cost crystallization cell within a CubeSat payload module to exploit the unique experimental conditions set aboard a sounding rocket. We designed a biaxial gimbal to house the crystallization experiments and take measurements on the protein solution in-flight with a spectrophotometry system. After flight, we used X-ray diffraction analysis to determine that flown protein has a structural rearrangement marked by loss of the protein's water and sodium in a manner that differs from crystals grown on the ground. We finally show that our gimbal payload module design is a portable experimental setup to take laboratory research investigations into exploratory space flights.

From aviation to automotive - a study on material selection and its implication on cost and weight efficient structural composite and sandwich designs

The design of a composite material structure is often challenging as it is driven by the trade-off between lightweight performance and production costs. In this paper, the boundaries of this design trade-off and its implications on material selection, geometrical design and manufacturability are analysed for a number of design strategies and composite material systems. The analysis is founded on a methodology that couples weight-optimization and technical cost modelling through an application-bound design cost. Each design strategy is evaluated for three levels of bending and torsional stiffness. The resulting stiffness-versus cost-range together constructs the design envelope and provides guidelines on the suitability and improvement potential of each case. Design strategies researched include monolithic, u-beam-, sandwich-insert- and sandwich-stiffened plates. Considered material systems include carbon-, glass, recycled carbon-, lignin- and hemp-fibre reinforced composites. Optimized sandwich designs are shown to have lowest design cost. Glass-, recycled carbon-, lignin- and hemp-fibre reinforced composite materials are all shown to reduce costs but at lower stiffness performance. Ultimately, the case study demonstrates the importance of early structural design trade-off studies and material selection and justifies introducing novel fibre systems in low-cost applications of moderate stiffness levels.

Growth of microorganisms in an interfacially driven space bioreactor analog

Fluid bioreactors in microgravity environments may utilize alternative methods of containment and mixing. The ring-sheared drop (RSD) is a containerless mixing device which functions in microgravity using surface tension for containment and mixes through interfacially-driven flow. To assess the feasibility of using interfacially driven flow devices, such as the RSD, as bioreactors, Escherichia coli growth and recombinant protein expression were analyzed in a ground-based analog of the RSD called the knife edge surface viscometer (KEV). Results demonstrated that the KEV can facilitate the growth of E. coli and that growth rate increases logarithmically with increasing knife edge rotation rate, similar to the standard growth method on Earth (orbital shaker). Furthermore, the KEV was shown to be viable for supporting recombinant protein expression in E. coli at levels comparable to those achieved using standard growth methods.

MHD surrogate model for convection in electromagnetically levitated molten metal droplets processed using the ISS-EML facility

Electromagnetic levitation experiments in space are an essential tool for thermophysical property measurement and solidification studies. In light of the need for material properties as inputs to industrial process modeling, investigators need new tools for efficient experiment planning. MHD surrogate modeling is a parametric method for prediction of flow conditions during processing using the ISS-EML facility. Flow conditions in model Au, Zr, and Ti_39.5Zr_39.5Ni₂₁ samples are predicted using the surrogate model. For Au, flow is shown be turbulent in nearly all experimental conditions, making property measurement difficult. For Zr, the flow is turbulent with the heater on and laminar with the heater off, allowing for property measurement during free-cooling experiments only. For TiZrNi, the flow is laminar under all experimental conditions, indicating that TiZrNi is an excellent candidate for EML experiments. This surrogate modeling approach can be easily applied to other materials of interest, enabling investigators to choose materials that will perform well in levitation and to tailor experiment parameters to achieve desirable flow conditions.

Evaluation of algorithmic, textual and pictorial forms of representation of standard operating procedures for error reduction in complex systems

A new concept has been developed to compare different ways of presenting instructions for action for evaluation procedures. The representation forms algorithm (A), image (I) and text (T) are examined with regard to the number of top events, error frequencies, execution times and subjectively perceived workload. For this purpose, a study was carried out with n = 93 test persons in the research flight, in which the test persons had the task of landing a passenger aircraft using the autopilot with different representation forms. Possible work errors 14 with 11 different steps in the representation. Results of positive work-task landing plane: algorithm 58 % (1.7/14 errors σ = 1.5), text 62 % (1.5/14 errors σ = 1.1), image 93 % (0.8/14 errors σ = 1.1).

Autonomous monitoring, analysis, and countering of air pollution using environmental drones

The effect of air pollution on the environment, economic and health of the people in the affected countries cannot be overemphasized. This paper investigates large scale air pollution elimination to remove pollutants that are already in existence in the environment. This method involves the use of Environmental Drones (E-drones) to autonomously monitor the air quality at a specific location. The E-drone flies up to a predetermined height (Ealtitude) every hour, measures the air pollutants at that location, implements on-board pollution abatement solutions for pollutants above the recommended threshold, and then flies back down to its location on the ground. The advantages of this system is its ability to measure air pollution concentration of CO₂, CO, NH₃, SO₂, PM, O₃ and NO₂, detect when they are too high, and implement on-board pollution abatement solutions as needed. This system's novelty lies in the fact that it not only detects when there is excessive pollution, but it also automatically deals with and abates the detected air pollution above earth. When multiple E-drones are used in different locations, a custom software generates an Air Quality Health Index (AQHI) map of the region that can be used for present and long-term environmental analysis.

Experimental study of consistency degradation of different greases in mixed neutron and gamma radiation

Many of the moving components in accelerator and target environments require lubrication. Lubricants in such environments are exposed to high fluxes of secondary radiation, which originates from beam interactions with the target and from beam losses. The secondary radiation is a mix of components, which can include significant fractions of neutrons. Lubricants are radiation-sensitive polymeric materials. The radiation-induced modifications of their structure reduce their service lifetime and impose additional facility maintenance, which is complicated by the environmental radioactivity. The study of the lubricants radiation resistance is therefore necessary for the construction of new generation accelerators and target systems. Nevertheless, data collected in mixed radiation fields are scarce. Nine commercial greases were irradiated at a TRIGA Mark II Research Reactor to serve for the construction of new accelerator projects like the European Spallation Source (ESS) at Lund (Sweden) and Selective Production of Exotic Species (SPES) at Legnaro, (Italy). Mixed neutron and gamma doses ranging from 0.1 MGy to 9.0 MGy were delivered to the greases. For an experimental quantification of their degradation, consistency was measured. Two of the greases remained stable, while the others became fluid. Post-irradiation examinations evidence the cleavage of the polymeric structure as the dominant radiation effect. Dose and fluence limits for the use of each product are presented. Apart from the scientific significance, the results represent an original and useful reference in selecting radiation resistant greases for accelerator and target applications.

Microgravity disturbance analysis on Chinese space laboratory

Many scientific experiments are conducted in space; therefore, it is critical to understand the microgravity environment of a space laboratory. The first Chinese cargo ship, Tianzhou-1 (TZ-1), entered space on 20 April, 2017 and later joined with the Tiangong-2 (TG-2) Chinese space laboratory. TZ-1 carried a high-precision electrostatic suspension accelerometer system (ES-ACC) for measuring the microgravity acceleration on the spacecraft and a microgravity-active vibration system (MAIS), which contained flexible quartz accelerometers (Q-ACC). The ES-ACC was able to provide a reduced-disturbance environment for the MAIS. The purpose of these two instruments was to validate novel technologies and as an opportunity to record the microgravity acceleration of TZ-1 and TG-2 in detail during spacecraft operation in different flight modes, with or without vibration isolation. The acceleration data were analyzed comprehensively in a time–frequency–amplitude spectrogram. Some periodical disturbances with orbital period and irregular signals related to certain in-orbit events were observed. After reducing those disturbances, the microgravity levels on TZ-1 and TG-2 could be resolved to better than 10⁻⁶ m/s² in the root mean square in the frequency of 0.01–10 Hz. These accurate measurements aboard the Chinese space laboratory will provide valuable information to optimize working conditions for scientific experiments.

Investigation on in-situ formed Al3V-Al-VC nano composite through conventional, microwave and spark plasma sintering

In the present study, the effect of heating methods has been studied on the microstructure and mechanical properties of in-situ formed Al₃V-Al-VC nano-composite. 5 and 15 wt % of VC were added to Al matrix and conventional and microwave sintering processes were performed at 600 °C. While spark plasma sintering process was done at 450 °C with initial and final pressure of 10 and 30 MPa, respectively. The XRD results revealed the formation of Al₃V intermetallic compound in microwave sintered sample, while in both spark plasma sintered and conventionally prepared specimens, the only crystalline phases were Al and VC. Microstructure studies, demonstrated a uniform distribution of 5wt% VC reinforcement in Al matrix but the 15wt%VC addition led to form agglomerates in all prepared samples. The highest bending strength (275 ± 13 MPa) and hardness (260 ± 13 Vickers) were obtained in the spark plasma sintered sample with 15wt% of VC content.

Optimization of positional parameters of close-formation flight for blended-wing-body configuration

In the present study, we study formation flight with two flying wing configurations. A low speed wind tunnel test is conducted to validate the accuracy of the Computational Fluid Dynamics (CFD). Two optimization procedures are implemented at a high subsonic speed. The free stream Mach number is kept at 0.85, the lead aircraft's angle of attack is 2°, and the following aircraft's angle of attack is 2° as well. The maximum lift-to-drag ratio of the following aircraft is achieved as the lateral spacing is 0.853 b, and the vertical offset is 0.022 b (b is the wingspan). As much as 24.7% induced drag reduction is achieved at the optimized state. A pair of counter-rotating vortices interact and weaken each other. By analyzing the Kriging model constructed in the optimization procedure, it seems that the following aircraft's aerodynamic performance is sensitive to lateral spacing and vertical spacing, but insensitive to longitudinal spacing in close-formation flight. The best drag reduction position places in the following aircraft's wing tip is positioned at the core of the leading aircraft's wing tip vortex.

Advanced Laser-Based Techniques for Gas-Phase Diagnostics in Combustion and Aerospace Engineering

Gaining information of species, temperature, and velocity distributions in turbulent combustion and high-speed reactive flows is challenging, particularly for conducting measurements without influencing the experimental object itself. The use of optical and spectroscopic techniques, and in particular laser-based diagnostics, has shown outstanding abilities for performing non-intrusive in situ diagnostics. The development of instrumentation, such as robust lasers with high pulse energy, ultra-short pulse duration, and high repetition rate along with digitized cameras exhibiting high sensitivity, large dynamic range, and frame rates on the order of MHz, has opened up for temporally and spatially resolved volumetric measurements of extreme dynamics and complexities. The aim of this article is to present selected important laser-based techniques for gas-phase diagnostics focusing on their applications in combustion and aerospace engineering. Applicable laser-based techniques for investigations of turbulent flows and combustion such as planar laser-induced fluorescence, Raman and Rayleigh scattering, coherent anti-Stokes Raman scattering, laser-induced grating scattering, particle image velocimetry, laser Doppler anemometry, and tomographic imaging are reviewed and described with some background physics. In addition, demands on instrumentation are further discussed to give insight in the possibilities that are offered by laser flow diagnostics.