Space Structures Research Articles

Hypervelocity impact investigations of composite truss tubes for in orbit assembly risk assessment

As the number of orbital structures increases, so does the threat posed by micrometeoroid and orbital debris (MMOD) impacts. These impacts range from the ballistic range (less than 1.5 km/s) to exceeding 20 km/s and can significantly weaken space structures such as the International Space Station (ISS), leading to further risk as the debris shed could damage the in-orbit assembly field. Space structures, including the James Webb Space Telescope (JWST) and the in-space assembled telescope (ISAT), often employ fiber-matrix composites in various shapes and sizes. While the effects of hypervelocity impacts (HVI) on flat plate composites have been extensively studied, there is a notable lack of research on HVI of composite tubes. Understanding how MMOD impacts affect the integrity of individual truss members, as well as the structure as a whole is essential for assessing the condition of existing space structures and improving future designs. To replicate MMOD impacts, HVI investigations from 1 to over 3 km/s were conducted on a specialized two-stage light-gas gun, showing the transition from single inlet wall damage to cascading internal fragmentation inside the tube, leading to increased damage with increasing velocity. Our investigation focuses on the image analysis of the damage area and ejecta fragmentation in the carbon fiber reinforced polymer (CFRP) tubes, as well as quantifying the resulting hole diameter. This data is crucial for validating corresponding computational models. In this study we present three separate methods of characterizing HVI including: impedance matching through equations of state, a hybrid Lagrangian finite element (FE) model using LS-DYNA with smoothed particle hydrodynamics (SPH), and experimental investigations. All methods agree that HVI can cause nearly three times the amount of damage within a tube compared to similar conditions on a plate. Our findings help enhance our understanding of MMOD impact risks on existing structures and contribute to the development of systems with greater resilience to HVI.

Multirobot Assembly Sequence Planning of a Large Space Telescope

As space structures trend toward larger scales and modularization, their on-orbit assembly presents a significant challenge. Assembly sequence planning is crucial in minimizing vibration and enhancing the efficiency of on-orbit construction. This paper explores the multirobot assembly sequence planning algorithm for a large space telescope. A dynamic model is firstly developed to analyze the vibration of segmented mirror pieces and the main satellite during assembly, taking into account the flexibility of connections at interfaces. The dynamic model is able to provide criteria for time efficiency and satellite attitude disturbances. Considering constraints during the assembly process, a modified multiobjective ant colony optimization algorithm capable of planning multirobot assembly sequences is implemented. The simulation results demonstrate that the proposed method not only facilitates parallel planning of multirobot assembly sequences but also leads to a reduction in assembly time and attitude disturbances of the main satellite. The results of assembly sequence planning provide dependable guidance for the subsequent planning levels, such as task planning and trajectory planning, of the on-orbit assembly task for large space telescopes.

PRELIMINARY ASSESSMENT OF THE ACUTE TOXICITY EFFECTS OF FRIED CAT FISH EXTRACT ON BIOCHEMICAL, HEMATOLOGICAL AND HISTOPATHOLOGICAL PARAMETERS OF WISTAR RATS

Some food processing techniques have been linked with formation of toxic chemicals known as Polycyclic Aromatic Hydrocarbons (PAHs), which are found in some processed foods and have been widely attributed to the prevalence of cancer of liver and stomach in Nigeria. However, the toxicological effects of the consumption of fried fish have not been adequately documented. Therefore, this study investigated the toxicological effects of PAHs in fried cat fish on Wistar rats. Fifty five rats were used in the study and they were divided into control and ten treatment groups with daily administration of fried fish extract at dosage of 200, 400, 600, 800 and 1000 mg/kg body weight to the rats for 14 days. The results showed that the activities of serum, alanine aminotransferase (ALT), alkaline phospherase (ALP), asparte aminotransferase (AST) as well as urea and creatinine concentration were affected across the treated groups of animals which were indications for hepatorenal damage. White blood cell (WBC) and mean corpuscular volume (MCV) showed significant changes in response to the administered dosage compared to the control. The liver showed no significant histopathological changes between the test rats and control. The architecture of sections of kidney treated groups was similar to that of the control in which the renal corpuscles maintained their normal size of urinary space and normal tubular structures with no necrosis observed. The result revealed that there can be potential toxicity if there is repeated indulgence to fried cat fish at the temperatures between 160 – 230 oC.

Interaction of driven ``cold'' electron plasma wave with thermal bulk via ion spatial inhomogeneity

Abstract Using high resolution Vlasov - Poisson simulations, evolution of driven ``cold" electron plasma wave (EPW) in the presence of stationary inhomogeneous background of ions is studied. Mode coupling dynamics between ``cold'' EPW with phase velocity $v_{\phi}$ greater than thermal velocity i.e $v_{\phi} \gg v_{thermal}$ and its inhomogeneity induced sidebands is illustrated as an initial value problem. In driven cases, formation of BGK like phase space structures corresponding to sideband modes due to energy exchange from primary mode to bulk particles via wave-wave and wave-particle interactions leading to particle trapping is demonstrated for inhomogeneous plasma. Qualitative comparison studies between initial value perturbation and driven problem is presented, which examines the relative difference in energy transfer time between the interacting modes. Effect of variation in background ion inhomogeneity amplitude as well as ion inhomogeneity scale length on the driven EPWs is reported.

Multifunctional bistable ultrathin composite booms with flexible electronics

Small satellites such as CubeSats pose demanding requirements on the weight, size, and multifunctionality of their structures due to extreme constraints on the payload mass and volume. To address this challenge, we introduce a concept of multifunctional deployable space structures for CubeSats based on ultrathin, elastically foldable, and self-deployable bistable composite structures integrated with flexible electronics. The multifunctional bistable booms can be stored in a coiled configuration and self-deploy into a long structure upon initiation by releasing the stored strain energy. The boom demonstrates the capabilities of delivering power and transmitting data from the CubeSat to the flexible devices on the boom tip. The boom also shows the ability to monitor the dynamics and vibration during and after the deployment. A payload boom has been installed in a 3 U CubeSat as flight hardware for in-space testing and demonstration. This effort combines morphable ultrathin composite structures with flexible electronics.

Navigating the body’s double nature in a sedentary environment: Swedish primary school children’s use of physical activity during the school day

ABSTRACT The structuring of time and space in schools influences when children’s bodies should be active and when they should be still. The growing interest in physical activity interventions in schools today highlights a pattern where schools act as sites meant to regulate and educate children’s bodies according to adult-centric interests. Drawing on existential phenomenology, particularly the dual nature of the body as both object and subject, this article examines how children themselves use physical activity in school. Sixty-three children aged 8 – 13 in Sweden participated in semi-structured focus groups where they discussed the significance of movement for them in the school environment. Reflexive thematic analysis in an ‘experiential mode’ was used to understand how the children related to their bodies in terms of objectivity and subjectivity, creating different types of incentives for movement. This is illustrated through two themes: ‘Physical activity for a healthy body (The body as object)’, which shows how children use physical activity based on instrumental motives, and ‘The sentient body (The body as subject)’, where the feeling body is presented in two states: both as trapped and as liberated. The children used movement as a way to balance the structuring of time and place imposed by their school environment, which generated various subjective corporeal states. Thus, the analysis shows that the school environment produces subjective bodies that children understand in objective terms influenced by contemporary health discourses, which in turn shapes their use of movement.

Multidisciplinary space shield origami composite: Incorporating cosmic radiation shielding, space debris impact protection, solar radiative heat shielding, and atomic oxygen erosion resistance

Origami composites have been extensively utilized in space structures with constrained payload volumes due to their capability to efficiently transform compact structures into larger surface area or volume configurations. The proposed origami composite incorporates hydrogen-rich benzoxazine polymers known for their high radiation shielding capability and ultra-high-molecular-weight polyethylene fibers known for their high ballistic performance, radiation shielding capability, and flexibility. The proposed origami composite and manufacturing method can enhance bonding strength by achieving precise origami shapes and utilizing the same matrix for both flexible and rigid components. Membrane sheets are manufactured at a low curing temperature to provide flexibility, while rigid facets are separately manufactured at a high curing temperature to increase rigidity. The integration of a polyimide protection layer significantly enhances space environment resistance and reduces mass loss due to atomic oxygen erosion. Despite a slight decrease in ballistic performance after exposure to space conditions, the proposed origami composite maintains superior ballistic performance compared to conventional space materials and conventional origami composites. Compared to existing origami composites or conventional space materials, the proposed origami composite exhibited superior radiation shielding performance. The laminated structure of the proposed origami composite can offer some solar radiation shielding capability. The proposed origami composite offers a multifunctional origami solution as a membrane-space shield material, fulfilling requirements for high ballistic performance, cosmic radiation shielding, solar radiative heat shielding, and space environmental resistance.

Extended Endoscopic Transsphenoidal Surgery with Total Cyst Wall Decollement for Suprasellar Cystic Craniopharyngioma: Case Report and Literature Review.

For most cystic craniopharyngiomas, intracapsular debulking is a good strategy to get a large operation space and protect vital structures. However, this surgical strategy may lead to the residual and recurrence of the tumor capsule wall. Therefore, there is an urgent need for a new surgical strategy without residual capsule walls for the removal of cystic craniopharyngiomas. We reviewed a 45-year-old male with vision loss and visual field defects, whose head MRI revealed a suprasellar cystic lesion. The patient underwent extended endoscopic transsphenoidal surgery. The surgical strategy of total cystic wall decollement was adopted, which was that the lesion surrounded by the capsule was completely separated from the surrounding tissue without destroying the capsule and maintaining the tension of the capsule. The lesion was totally resected and pathological findings confirmed the diagnosis of craniopharyngioma. After the operation, both the visual acuity and pituitary function were significantly improved. In addition, he suffered from transient diabetes insipidus, which was subsequently relieved. During the 33-month follow-up, there was no tumor recurrence. Compared with the traditional surgical strategy of intracapsular debulking, the surgical strategy of total cystic wall decollement has the advantages of less residual tumor capsules, low tumor recurrence rates, etc. Therefore, for specific cystic craniopharyngiomas, the surgical strategy of total cystic wall decollement may be an effective surgical strategy to reduce tumor recurrence.

The aroma of toasted oak wood (<i>Quercus petraea</i>): from sensory analysis to molecular characterisation

The chemical complexity of the aroma compounds developed by oak wood during the toasting process is known to contribute to the quality of wines and spirits after barrel ageing. Molecular characterisation of toasted oak wood has increased steadily in recent years, using the traditional olfactory-guided approach by gas chromatography coupled with olfactometry and mass spectrometry (GC-O-MS); however, few studies have focused on its sensory characterisation. In this study, a sensory characterisation of oak wood (Quercus petraea) was first carried out during toasting in order to identify any descriptors that had not yet been characterised from a molecular point of view. Thus, in the second part of this work, we were able to identify volatile compounds associated with the aroma of toasted oak wood.Based on previous work in oenology, the sensory characterisation of oak wood was carried out in three stages: identification, structuring and description of a sensory space. Data processing of the 215 descriptors generated by the panel of experts revealed six descriptors specific to the aroma of oak wood throughout its toasting (i.e., fresh wood, fresh green, sweet, roasted, spicy and smoky). The results were represented graphically in the form of an aroma wheel, which was used to highlight the descriptors that had not yet been characterised from a molecular point of view. Thus, two volatile compounds were identified: thymoquinone (pencil and cedar odour) and verbenone (fresh, menthol and tealeaf odour). Their evolution in oak wood during toasting and their distribution in different wood species used in oenology (sessile oak, pedunculate oak, American oak, Caucasian oak, acacia and chestnut) were studied. Their sensory impact was studied by assessing their olfactory detection threshold in a model wine solution. The thresholds were evaluated at 49 ng/L for thymoquinone and 193 µg/L for verbenone.

Design of Docking Interfaces for On-Orbit Assembly of Large Structures in Space

Considering the complexity of on-orbit assembly during space missions and the super-large size of space structures, this paper presents the design for a new type of docking interface with an androgynous body that exhibits a number of advantages, including high connection strength and a compact structure. The androgynous body has a conical guided symmetric design with a symmetry of 90°. The geometric design of the docking surface is described in detail in order to prove its advantages. Structural design was carried out using UG modeling as well as dynamic simulation using Recur Dyn to obtain the displacement coordinate curves of the docking port. The geometry of the docking port’s high docking misalignment tolerance was verified, and misalignment tolerance and lens splicing experiments were also performed. The docking port’s ability to be quickly connected or disconnected within a translation tolerance of 23.5 mm and a tilt tolerance of 24° was verified. This article provides a useful reference for space missions in terms of module docking and on-orbit assembly.

Controlling Chlorine-Doped Nickel Diselenide Ultrathin Nanosheets through Steric Effects: An Electrocatalyst for Oxygen Evolution Reaction and Urea Oxidation Reaction.

Exploration of electrocatalysts suitable for the oxygen evolution reaction (OER) and urea oxidation reaction (UOR) is essential for electrocatalytic hydrogen production. In this work, a ligand substitution strategy is used to synthesize ultrathin-nanosheet electrocatalysts of Cl-doped NiSe2 (NiSe2-a and NiSe2-b), which exhibit high-electrocatalytic activity during OER and UOR. NiSe2-a and NiSe2-b only need an overpotential of 227 and 268 mV, respectively, to achieve a current density of 10 mA cm-2 during OER. Furthermore, NiSe2-a with its smaller steric effects exhibits excellent catalytic performance for UOR, requiring an ultralow potential of 1.360 V to deliver a current density of 100 mA cm-2. This excellent performance can be attributed to the nonmetallic elements (Se and Cl) modulating and optimizing the charge state of the metal sites, thereby increasing the electrocatalytic activity. Overall, this work provides an unparalleled example of tuning space structures to design efficient electrocatalysts and has promising industrial applications.

Estimation and research of the temperature field models of large space spherical mesh shell structures under localized fire

This paper firstly investigated fire dynamics characteristics and the temperature field distributions of large space spherical mesh shell (SMS) structures under localized fire in FDS, and divided the temperature fields into plume region, smoke accumulation region and ceiling jet region. Based on the classical axisymmetric plume model, the predictive models for the steady-state and transient temperature fields in different fire regions for large space SMS structures were proposed in this paper. Thereafter, the proposed temperature models were compared with the simulated results and experimental test results by other scholars, and they were in good agreement. In order to further discover the realistic fire development progress and temperature distribution of large space fire, and validate the proposed temperature field models, this paper designed and conducted three full-scale large space fire tests (Test-1 ∼ Test-3) with different fire source powers in a large space building. Results showed that temperature fields of large space fires could be consisted of near-fire region (Flame region) and far-fire region (Plume region and Ceiling jet region). The steady-state fire source powers were tested for 443 kW, 886 kW, 1090 kW for Test-1, Test-2 and Test-3, respectively, while their maximum temperatures of the roof reached 75 °C, 105 °C and 120 °C. Based on McCaffrey plume model, we further proposed the transient temperature model in flame region for large space structures, and its accuracy was verified by the test results. Moreover, the proposed steady-state and transient temperature fields for large space SMS structures were compared with the tested temperature field data, and the tested and predicted temperature curves were generally in good agreement in plume and ceiling jet regions. Finally, the test results aimed to provide a scientific basis and reference for the fire safety and structural fire-resistant design of large space buildings.

Semi-analytical computation of bifurcation of orbits near collinear libration point in the restricted three-body problem

A unified semi-analytical solution is presented for constructing the phase space near collinear libration points in the Circular Restricted Three-body Problem (CRTBP), encompassing Lissajous orbits, quasihalo orbits, Axial orbits, and their invariant manifolds, as well as transit and non-transit orbits. Based on classical in-plane and out-of-plane frequency resonance mechanisms, the Lindstedt–Poincaré method could only derive separate analytical solutions for the invariant manifolds of Lissajous orbits and halo orbits, falling short for the invariant manifolds of quasihalo orbits. In this paper, by introducing a coupling coefficient η and a bifurcation equation, a unified series solution for these orbits is systematically developed using a coupling-induced bifurcation mechanism and Lindstedt–Poincaré method. Analyzing the bifurcation equation obtained from different coupling forms reveals bifurcation conditions for all kinds of orbits near collinear libration points. When η = 0, the series solution describes non-bifurcated orbits, while when η ≠ 0, the solution describes bifurcated orbits, including quasihalo orbits, Axial orbits, and their invariant manifolds, as well as newly bifurcated transit and non-transit orbits. This unified semi-analytical framework provides a more comprehensive understanding of the complex phase space structures near collinear libration points in the CRTBP.

Conductive paths generation using topology optimization for worst-case thermal design in space systems

Designing thermal systems for space platforms is a challenging task due to the wide variability in thermal conditions during the orbit and the strict constraints imposed by other subsystems. Several strategies have been developed to address these challenges while minimizing the thermal control subsystem’s signature, encompassing different algorithms optimize components positions in the platform. When relocation is not possible, thermal couplings between components can be modified to enhance heat transfer and achieve more uniform temperature distribution. To design optimal thermal paths in 2D space structures, in this paper a topology optimization framework based on the Heaviside Projection Method is introduced, using the Lumped Parameter Method (LPM) and taking the radiation heat transfer into account. The algorithm’s performance is tested on a Printed Circuit Board (PCB) by designing an optimal copper layer to meet specific thermal requirements under both extreme hot and cold conditions. Results show a significant improvement in thermal compliance for all components with the addition of this high-conductivity layer. Additionally, a reduction method is introduced to transfer the material distribution from the optimization to a coarser mesh of any size, which is useful to facilitate its implementation in existing software, where a large number of degrees of freedom can be a limitation.

Potential difference-induced electrodeposition of defect-rich α-cobalt hydroxide on porous copper (PCu): High-voltage performance of supercapacitor

Designing electrode materials for aqueous battery-type supercapacitors to extend the operating voltage window remains a significant challenge to increase the energy density of aqueous supercapacitors. In this work, a directional electrodeposition method without any additives was employed to deposit α-Co(OH)2 onto a porous copper (PCu) current collector substrate, which involves the fabrication of a supercapacitor electrode material with a cross-linked network structure named α-Co(OH)2@PCu900. The potential difference between copper and cobalt facilitated the formation of a larger interlayer spacing for α-Co(OH)2. In addition, crystals of α-Co(OH)2 with different orientations exert stress on one another, leading to lattice distortion and vacancy formation. The morphology and microstructure of materials were analyzed through techniques such as SEM, HRTEM, XRD, and XPS, confirming the validity of the experimental design. This defect-rich, large interlayer spacing structure facilitates ion intercalation and deintercalation during the charge-discharge process, thereby expanding the operating voltage window. In a three-electrode system, α-Co(OH)2@PCu900 exhibited a potential range from −0.45 V to 0.55 V and demonstrated an areal capacitance of 2580 mF cm−2 and specific capacitance of 600 A g−1 at 2 mA cm−2. The α-Co(OH)2@PCu900 was used as the cathode material and commercial reduced graphene oxide (rGO) was used as the anode material in an asymmetric supercapacitor, and the ASC device exhibited an areal capacitance of 295.3 mF cm−2 and a specific capacitance of 87.89 F g−1. Notably, it retained a high energy density of 0.12 mW h cm−2 (35.27 Wh kg−1) at a power density of 1.7 mW cm−2 (505.95 W kg−1). This method established α-Co(OH)2@PCu900 as a promising supercapacitor electrode material, providing a viable strategy for designing and fabricating functional electrode materials.

Passive low-frequency vibration mitigation in large space structures

Passive low-frequency vibration mitigation in large space structures

Supporting driver performance in closely spaced tunnel-interchange structure: Traffic control devices and effects on driving behavior

Objectives With the rapid development of expressways in the mountainous regions of southwestern China, closely spaced tunnel-interchange structures have inevitably emerged due to topographical constraints and environmental limitations. Given the unfavorable road geometry and rapid cross-section transitions, drivers face significant safety concerns. This study aims to investigate drivers’ safety performance at closely spaced tunnel-interchange sections and determine how safety risks can be mitigated through improved traffic control devices design. Methods Thirty-nine participants conducted an experimental study in a fixed-base simulator. The test scenario was modeled on the Xingyan Freeway-S3801 and accurately reproduced in the simulator. For each safety performance metric, the driving simulator experiments yielded a dataset with 780 observations. To address the idiosyncratic variation due to individual driver differences, a series of linear mixed effects models (LMM) were developed to analyze drivers’ behavior responses. Results In closely spaced tunnel-interchange sections, a general impairment of both longitudinal and lateral performance was observed. This study identified potential critical impact variables in traffic control device systems. According to the LMM results: (a) Removing the 0.5 km interchange ramp exit advance guide sign located in the tunnel exit area reduces dangerous behavior in the corresponding impact area. (b) Replacing the 0.5 km interchange ramp exit advance guide sign with arrow pavement markers as an information source supports improved driver performance, promoting driver safety. (c) Adding tunnel exit distance signs within tunnels is recommended to enhance situation awareness for drivers. Conclusions This study addresses the scientific issues related to traffic control devices setup for closely spaced tunnel-interchange sections, focusing on identifying potential critical impact variables. The findings provide guidance on the design of traffic control devices for such sections and support revisions to national engineering standards.

Seismic performance of pentagonal type aluminum alloy suspen-dome structure with large opening

Prestressing technology is an effective way to enhance the mechanical properties of space structures. In view of this, a new pentagonal type aluminum alloy suspen-dome structure with large opening is proposed in this paper by introducing the lower cable support system into the aluminium alloy single-layer reticulated shell structure. The seismic performance of this new structure is investigated using time-procedure analysis. Firstly, the effects of rise-span ratio, thickness-span ratio, prestressing level, horizontal radius factor for lower chord nodes and roof loading on the free vibration characteristics of the structure with different supporting stiffness are investigated. The distributions of internal forces and displacements of members of overall structure considering lower support and roof structure only are analyzed. Subsequently, the dynamic response of the structure under seismic combinations of different dimensions and directions is investigated, and reasonable combinations that should be considered for simplified analyses are derived. Furthermore, seismic internal force coefficients are introduced to assess the degree of seismic effects on various types of members. On this basis, parametric analysis of the seismic performance of the structural performance is conducted and quantitative assessment of the sensitivity of the parameters is carried out. Additionally, the free vibration characteristics and dynamic performance of steel and aluminium suspen-dome are compared. The results show that considering the supporting structure weakens the structural stiffness while increasing the structural dynamic response; reasonable values of key parameters in the seismic design of the structure are obtained; and the rise-span ratio and thickness-span ratio are important influencing factors of the seismic performance of the structure. Besides, the internal forces of members in aluminium alloy suspen-dome are less affected by seismic effects than those in steel suspen-dome, and the new structure has good seismic performance.

Оценка влияния процесса цифровизации и новейших технологий на структуру профессионального пространства в современном информационном обществе

This study aims to examine the characteristics of the structure of professional spaces in the modern infor-mation society. Using a systematic approach, the author highlights the dynamics of professional space struc-tures influenced by the broader context of modern society and the specific process of digitalization. The analy-sis explores new algorithms of interaction among participants within the professional space, which arise as a result of adopting the latest technologies. The advent of internet technologies and mobile phones has simpli-fied communication among these participants, altering spatial and temporal barriers. The modern professional becomes more “liberated”, which often leads to reduced efficiency due to the emergence of new actors who become significant components within the system. The multiplicity of actors in the modern professional space diminishes the role of the “classical” professional, who previously served as a system-forming element of this space. The author argues that while new technologies increase the mobility of professionals, they also impose new demands. Individuals must adapt to these changes, leading to conflicts both among specialists and across different generations.

Recycling of Spent Graphite from Lithium-Ion Batteries for Aqueous Zn Dual-Ion Batteries.

As lithium-ion batteries (LIBs) become more widespread, the number of spent LIBs gradually increases. Until now, recycling of spent LIBs has mainly concentrated on high-value cathodes, but the anode graphite has not yet attracted wide attention. In this work, spent graphite from LIBs was oxidized to graphene oxide and then thermally reduced to reduced graphene oxide (RGO), which serves as the cathode of aqueous Zn dual-ion batteries (ZDIBs). The thermal reduction process enables RGO with a large layer spacing and porous structure, which increase the anion insertion sites and transfer kinetics. As a result, the corresponding battery exhibits a high specific capacity of 96.82 mAh g-1 at 1 A g-1, superior rate capability, and a high capacity retention rate of 80% after 2000 cycles. Moreover, RGO gradually transforms into a long-range disordered structure during the cycling process, which provides more transport routes and active sites for anion insertion and thus leads to the increase of capacity. This work combines the recycling of spent graphite with aqueous ZDIBs, realizing the high-value use of spent graphite.