Backup Structure Research Articles

Finite Element Model Updating Method for Radio Telescope Antenna Based on Parameter Optimization with Surrogate Model

There are deviations between the radio telescope antenna finite element (FE) model, founded on the design stage, and the actual working antenna structure. The original FE model cannot accurately describe the antenna structure deformation characteristics under the environmental load, thereby compromising the accuracy of the active structural compensation. This article proposes an antenna FE model updating method founded on parameter optimization with a surrogate model. The updating method updates the modulus of elasticity parameters of different components of the antenna backup structure (BUS) to obtain finite element analysis (FEA) results consistent with the actual measurement of the antenna reflector surface shape. The surrogate model founded on the multi-quadratic radial basis function (RBF) improves the computational efficiency of FE model updating, replacing the complex and time-consuming finite element analysis and calculation process. This method is implemented on a radio telescope antenna with an aperture of 25 m. The results show a significant reduction in the mismatch between the antenna and the updated FE model. This method’s calculation time is significantly reduced compared with the updating method without using the surrogate model, with the RBF surrogate model taking 1% of the time of the finite element model in the FEA calculations. The proposed method can improve the antenna FE model calculation accuracy and significantly enhance the efficiency of FE model updating calculations. Thus, it can offer a reference for antenna engineering practice.

Embodied Carbon Impacts of Building Envelope Systems

Abstract As buildings become more energy efficient due to stringent building codes, the emphasis on reducing the embodied carbon (EC) in the built environment has become significant. Studies predict that between 2020 and 2050, new buildings will surpass operational emissions with higher embodied emissions in their initial decade and throughout their life cycle. To meet decarbonization targets, reducing EC through low-carbon, high-performance building designs and grid decarbonization is crucial. This research analyzes the embodied carbon intensity of 26 commonly used envelope systems of large buildings in Ontario’s Greater Toronto and Hamilton Area (GTHA) using the attributional life cycle assessment (ALCA) methodology. Results highlight the impact of cladding materials, insulation layers, and backup structures on EC. The study ranks envelope assemblies based on their EC intensity (ECI), providing insights for designers to balance operational and embodied emissions. Noteworthy findings include the relatively high ECI of floor systems compared to exterior wall and roof systems. It also emphasized the challenges in assessing the environmental impacts of wood-based products and the need for uncertainty analysis and transparent reporting. The study contributes to understanding EC in building envelopes, guiding design teams toward low-carbon structures and more informed decision-making. As research progresses, recommendations include consequential analysis, assessing biogenic carbon impacts, and material durability studies for a deeper insight on the environmental impacts of building envelope materials.

Application of Infrared Thermal Imager to measure the temperature of Back-Up Structure of the TianMa radio telescope

Application of Infrared Thermal Imager to measure the temperature of Back-Up Structure of the TianMa radio telescope

Modeling and Analysis of the Active Surface System for the Large Single-Dish Sub-mm Telescope

Enlarging antenna diameter while maintaining an accurate reflective surface is important in the development of next-generation single-dish sub-mm telescopes. In this article, we propose an emulation and optimization method of the active surface system (EOMASS) for large single-dish sub-mm telescopes. The proposed method involves three main steps: 1) building an active surface system model (ASSM) based on the whole finite element model (FEM) of the large single-dish sub-mm telescope, which includes the main reflector, realistic adjustment models of actuators, backup structure and so on; 2) emulating the reflective surface deformation compensation under gravity based on the initial distribution of the actuators with the ASSM, in consideration of the manufacturing error of panels; and 3) further optimizing the number and distribution of actuators based on the illumination function, and predicting the performance of the sub-mm antenna due to the limited number of faulty actuators. As an application example, a 60 m single-dish sub-mm telescope is analyzed under gravity with the proposed EOMASS. The results demonstrate that the proposed EOMASS is an effective and advanced method, providing a feasible precision design of the active surface system for a large single-dish sub-mm telescope.

Facilitating conditions for staff’s confidence to enforce school tobacco policies: qualitative analysis from seven European cities

BackgroundSchool staff members’ consistent enforcement of school tobacco policies (STPs) is needed to decrease adolescent smoking and exposure to tobacco smoke. Staff’s confidence, indicating their perceived ability to cope with students’ negative responses, explains variations in staff’s STPs enforcement, yet understanding of the determinants for confidence is lacking. We analyzed the conditions in which the staff feel confident in addressing students who violate STPs to support staff’s enforcement. MethodsData consists of 81 semi-structured interviews with the staff members from 26 secondary schools in seven European cities in Belgium, Finland, Germany, Ireland, Italy, The Netherlands, and Portugal. In every city, 3–4 staff members (senior management, teachers, supportive staff) in 3–4 schools (academic–vocational, high–low SES area) were interviewed. Transcripts were analyzed with thematic analysis.ResultsWhen staff felt confident in their ability to prevent, diminish, or handle students’ negative responses, they were more likely to address students on STP violations. The staff was more confident (1) when consistent policy enforcement within school and regarding the wider society ensured staff legitimacy for STPs enforcement, (2) when dialog and mutual familiarity with students allowed the staff to facilitate constructive interaction with STP violators, and (3) when organizational backup structures provided staff collegial support to overcome challenges in the enforcement. These conditions would support consistent enforcement, especially with persistent misbehavers and among the more uncertain staff members.ConclusionsOur study stresses the need to implement strategies at multiple levels to strengthen staff’s confidence for STP enforcement. To support staff’s legitimacy for enforcement, we suggest reinforcing structures and practices that facilitate consistency in STP enforcement; to support staff’s ability for constructive interaction with STP violators, we suggest strengthening staff’s social and emotional learning; and to support staff’s experience of collegial support, we suggest reinforcing staff’s collective ability to cope with students’ negative responses.

Thermal Analysis of the Backup Structure of the Tianma Telescope

Taking the Tianma Radio Telescope (TMRT) as an object, this paper focuses on the determination of temperature gradients and thermal deformations of the backup structure (BUS) with the finite element method. To this end, a modeling and analysis method, which consists of a simplified FEM and a four-component simulation process, is proposed. In the development, only solar radiation is considered and thermal convection is neglected. Based on the thermal time constant of the BUS, the simulations of temperature gradients are simplified as static analysis. The superposed temperature gradients agree well with the ones measured by thermometers with a 0.57°C root mean square (rms) error. In addition, the illuminated-weighted rms errors of the primary reflector surface calculated by the simulation and measured by the extended out-of-focus holography are in good agreement. The rms error increases approximately 170 μm when the Sun persistently illuminated the BUS for 3 hr. The optimized initial temperature of the antenna structure is 20°C by comparing the results between the finite element analysis and the e-OOF measurement. The thermal deformation database can support the real-time compensation of the active surface system if the traces of the radio telescope are known in advance.

Non-uniform temperature distribution of the main reflector of a large radio telescope under solar radiation

The non-uniform temperature distribution of the main reflector of a large radio telescope may cause serious deformation of the main reflector, which will dramatically reduce the aperture efficiency of a radio telescope. To study the non-uniform temperature field of the main reflector of a large radio telescope, numerical calculations including thermal environment factors, the coefficients on convection and radiation, and the shadow boundary of the main reflector are first discussed. In addition, the shadow coverage and the non-uniform temperature field of the main reflector of a 70-m radio telescope under solar radiation are simulated by finite element analysis. The simulation results show that the temperature distribution of the main reflector under solar radiation is very uneven, and the maximum of the root mean square temperature is 12.3°C. To verify the simulation results, an optical camera and a thermal imaging camera are used to measure the shadow coverage and the non-uniform temperature distribution of the main reflector on a clear day. At the same time, some temperature sensors are used to measure the temperature at some points close to the main reflector on the backup structure. It has been verified that the simulation and measurement results of the shadow coverage on the main reflector are in good agreement, and the cosine similarity between the simulation and the measurement is above 90%. Despite the inevitable thermal imaging errors caused by large viewing angles, the simulated temperature field is similar to the measured temperature distribution of the main reflector to a large extent. The temperature trend measured at the test points on the backup structure close to the main reflector without direct solar radiation is consistent with the simulated temperature trend of the corresponding points on the main reflector with the solar radiation. It is credible to calculate the temperature field of the main reflector through the finite element method. This work can provide valuable references for studying the thermal deformation and the surface accuracy of the main reflector of a large radio telescope.

New design of large fully-steerable radio telescope reflector based on homogenized mesh structure

The self-weight of a large fully-steerable radio telescope is one of the important factors affecting its performance. In the existing reflector system scheme, the problem of surface accuracy caused by its large and heavy structure has seriously restricted the application and implementation of large radio telescopes. Therefore, a new mesh structure scheme for a large fully-steerable radio telescope reflector is proposed in this paper. This scheme is based on a homogenized mesh back-up structure in the form of a quasi-geodesic grid and regular quasi-tri-prism or tetrahedron, which can significantly reduce the structural complexity and self-weight of the reflector under the condition that the reflector can meet the desired performance requirements. Finally, the feasibility and rationality of the scheme are evaluated by numerical simulation analysis, which has significant advantages and provides a new design for the reflector of a large fully-steerable radio telescope.

Questions of the overall dependability of the scada system in the corporate infrastructure

The paper considers the peculiarities of the SCADA (energy infrastructure management system in the railway infrastructure), as well as issues of the overall dependability in the corporate infrastructure, which is the aim of the study. The study, based on the accepted structure and values of the parameters, examines what depends on and how the readiness factor of a SCADA system changes when the recovery intensity changes and at a fixed failure rate. The results show that with increasing recovery intensity, the readiness factors of the telecommunications network and SCADA system thus defined increase, while reducing the downtime. For a more in-depth study of the overall reliability of the SCADA system, it is necessary to set specific normatively accepted dependability parameters of all connected elements, as well as a real set structure. Based on the fact that with backup resources provided, a defined dependability of the system can be ensured at preset values of the reliability parameters of its components and the backup structure; the opposite problem can also be solved. The proposed approach for studying the reliable behavior of the SCADA system within the corporate infrastructure can be noted as a contribution of the present work and conclusions are made for the practical use of the results.

CONSIDERATION OF SIGNIFICANT FACTORS AND LIMITATIONS IN THE STUDY AND DEVELOPMENT OF PASSIVELY RESERVED AIRCRAFT SUBSYSTEMS, TAKING INTO ACCOUNT TOLERANCES

Objectives.The relevance of this article lies in the fact that the problem of increasing the reliability of subsystems of aviation and rocket and space technology in case of sudden independent refusals determines one of the important areas of scientific research. The work is aimed at identifying and analyzing specific features that must be considered when researching and developing passively redundant subsystems, taking into account tolerances in case of sudden independent failures.Method.During the study, calculations were carried out using the methods of probability, search. The necessity of taking into account assigned and implemented tolerances, multiple and non-multiple reservation, discrete scales of realizable tolerances with different levels of significance, critical probabilities, determining the probability ranges of elements, where redundancy is profitable and unprofitable, is shown.Result.The possibility of implementing any tolerance for different values of a number of increasing individual multiplicities is revealed, which allows for a given tolerance to pose the task of finding the optimal multiplicity and its corresponding optimal backup structure in the interests of ensuring maximum reliability of the redundant subsystems. Analysis of the presented dependencies for the implemented tolerances of the first and second levels shows that for each tolerance level there are equilibrium values ???????????? at which the critical values of p_kr practically do not change depending on the multiplicities ????????.Conclusion. A different nature of the change in the critical probabilities ???????????? was found depending on the multiplicities for different values of the tolerances to be realized. So, with tolerances of the first level, larger than 25%, with increasing multiplicity, p_kr increases and smaller than 25% decreases with increasing multiplicity. The similar nature of the change in the p_kr values has a 28.6% tolerance for the implemented second-level tolerances.

Nonvolatile Spin-Based Radiation Hardened Retention Latch and Flip-Flop

Reduction of leakage power and vulnerability to radiation are of critical challenges in modern nanometer CMOS technologies because of scaling down requirement. Spintronic logic has been progressed to realize these demands based on magnetic-based elements properties especially magnetic tunnel junction (MTJ) such as radiation-hardened, non-volatility, and CMOS process compatibility. A novel soft-error tolerant and highly reliable latch circuit is proposed in this paper which is a promising choice for reliable and low-power architectures. Furthermore, employing the proposed shadow latch based on MTJ cells as a backup structure along with the rad-hard main latch is aimed to the realization of a nonvolatile and SEU-immune flip-flop which is applicable in next-generation CMOS circuits. Simulations of proposed circuits have been performed by SPICE tool and a 45 nm CMOS technology model to evaluate the effectiveness of topologies.

Measuring and analyzing thermal deformations of the primary reflector of the Tianma radio telescope

The primary reflector of the Tianma Radio Telescope (TMRT) distorts due to the varying thermal conditions, which dramatically reduces the aperture efficiency of Q-band observations. To evaluate and overcome the thermal effects, a thermal deformations measurement system has been established based on the extended Out-of-Focus holography (e-OOF). The thermal deformations can be measured in approximately 20 min with an illumination-weighted surface root mean square (RMS) accuracy of approximately 50 μm. We have measured the thermal deformations when the backup and front structure were heated by the sun respectively, and used the active surface system to correct the thermal deformations immediately to confirm the measurements. The thermal deformations when the backup structure is heated are larger than those when the front structure is heated. The values of half power beam width (HPBW) are related to the illumination-weighted surface RMS, and can be used to check the thermal deformations. When the backup structure is heated, the aperture efficiencies can remain above 90% of the maximum efficiency at 40 GHz for approximately two hours after one adjustment. While the front structure is heated, the aperture efficiencies can remain above 90% of the maximum efficiency at 40 GHz, and above 95% after one adjustment in approximately three hours.

An Enhanced Methodology for Lightweighting a Vehicle Design Considering Front Crashworthiness and Pedestrian Impact Safety Requirements

The front body structure of an automobile should have sufficient stiffness and strength to protect the occupants during a high speed frontal collision; simultaneously, it should not induce unduly high impact loads during a low speed pedestrian collision. The above requirements appear to be in conflict with each other. Traditionally, the design solutions for crashworthiness and pedestrian safety have been addressed separately by designing the front rails and back-up structure of a car for crashworthiness and occupant safety, while optimizing the front bumper for pedestrian impact protection. In the current study, it is shown that it would be more prudent to pose the tasks of designing a vehicle for frontal impact and pedestrian impact safety as a single problem of weight reduction (i.e. lightweighting) by considering major vehicle crash safety requirements in the form of US-NCAP (United States New Car Assessment Program) and IIHS (Insurance Institute for Highway Safety) offset impact test standards, and pedestrian impact safety according to the EEVC/WG17 (European Enhanced Vehicle-Safety Committee/Working Group 17) standard. To illustrate this methodology, a finite element model of a passenger car sold in the USA at one time is chosen and simulation is carried out extensively in the form of nonlinear explicit dynamic analysis using a robust commercial solver viz. LS-DYNA.

Topology optimization of reflector antennas based on integrated thermal-structural-electromagnetic analysis

In the area of structural design of reflector antennas, the existing researches mainly focus on size/shape optimization or just optimizing for structural performances (e.g., the reflector surface accuracy). Reflector antennas are one kind of equipment which is finally judged by its electromagnetic performances, and topology optimization has been proven a powerful method for structural design. In this paper, an integrated thermal-structural-electromagnetic (TSE) analysis procedure based on topology variables for reflector antennas is established for the first time. Then, topology optimization of the backup structure (BUS) of reflector antennas is developed and solved by genetic algorithms (GA) with bit-matrix representation of chromosome. The proposed optimization design method takes both the electromagnetic performance (antenna gain) and structure performance (total weight) into consideration. Numerical examples of BUS topology optimization of maximum gain with weight constraint are carried out. For comparison, a traditional minimum compliance design is also performed. The results illustrate the validity and effectiveness of the proposed method in the topology optimization of reflector antennas.

Conceptual Design of the Aluminum Reflector Antenna for DATE5

DATE5, a 5 m telescope for terahertz exploration, was proposed for acquiring observations at Dome A, Antarctica. In order to observe the terahertz spectrum, it is necessary to maintain high surface accuracy in the the antenna when it is exposed to Antarctic weather conditions. Structural analysis shows that both machined aluminum and carbon fiber reinforced plastic (CFRP) panels can meet surface accuracy requirements. In this paper, one design concept based on aluminum panels is introduced. This includes panel layout, details on panel support, design of a CFRP backup structure, and detailed finite element analysis. Modal, gravity and thermal analysis are all performed and surface deformations of the main reflector are evaluated for all load cases. At the end of the paper, the manufacture of a prototype panel is also described. Based on these results, we found that using smaller aluminum reflector panels has the potential to meet the surface requirements in the harsh Dome A environment.

Structural design methodology of electro-optical system installation on special mission jet transport aircraft

The research reported in this paper investigated the structural design methodology of equipping a jet aircraft modified for maritime patrol with any type of observation system. The study includes installation feasibility, definition of mounting types (fix/retractable), installation location, airworthiness requirements, design considerations, structural design requirements, and static/dynamic analysis considerations. Due to lack of design publication in this field, this study focuses on methodology of electro-optical sensor installation as a flowchart leading to a road map to equip an aircraft with any type of maritime sensor. For validation of above methodology, a case study for installation of an electro-optical system on a particular jet aircraft with new mission is presented. By comparison of system and aircraft specification based on methodology flowchart, a retractable mounting was chosen. To accomplish a safe installation, an optimal mechanism suitable with aircraft fuselage and required backup structure was designed using reinforced cut out. The design was then analyzed for static and dynamic critical load cases using MSC/NASTRAN software.

Study of the Effects of Heat Load, Ablator Density and Backup Structure upon the Thermal Protection Performance of Heat Shield Systems Consisting of Phenolic Carbon Ablators

Study of the Effects of Heat Load, Ablator Density and Backup Structure upon the Thermal Protection Performance of Heat Shield Systems Consisting of Phenolic Carbon Ablators

Preliminary Research on Connecting Strategy between Back-Up Structure and Alidade for 110-m QitTai Radio Telescope

The QTT (QiTai 110m radio telescope) antenna, with large aperture and high main-reflector surface precision, whose connecting strategy between back-up structure and alidade was investigated. In order to make the reflector surface deformation coordinated, the connecting strategies of “umbrella supporting”, “space truss” and “double gear” structure were constructed and analyzed based on FEM (finite element method). The results show that “double gear supporting” is superior to “space truss structure”, and the latter is better than “umbrella supporting”, while in the “umbrella supporting structure”, the smaller cone angle is good for reflector deformation coordination. These structures are easy to achieve antenna structure “homology” design.

Smart glass facade subjected to wind loadings

The design of a modern glass facade translates an architectural aspiration for transparency. Innovative technological solutions have made it possible to materialise a transparent planar surface, exploring the load-bearing capabilities of the glass itself. Facades also need to have back-up structures, which are designed to withstand seismic and wind actions. This paper analyses the behaviour of a ‘smart' glass facade, based on a bow-string truss solution, which is able to continuously adapt its shape in order to compensate for the wind dynamic displacements, affecting the structural appearance. The wave superposition method is used to generate samples of the wind distributions, using sinusoidal functions. A proportional–integral–derivative control strategy enables a significant reduction of the displacements shown by the facade during wind events. This design approach yields an optimised structural solution in terms of weight, allowing the materialisation of a very light facade.

A New Type Aluminum Alloy Backup Frame of FAST Project

Distinct from conventional truss, FAST project reflector elements require light weight, high accuracy backup structure. A new type of aluminum alloy frame backup element is designed and simulated. According to which, an aluminum alloy backup element prototype is manufactured and assembled at the under-construction site. And with a serial of measure experiments, the prototype data meets the requirements. Thus the design and experiments verify the efficiency of the structure.