Design Procedure Research Articles

Development and Experimental Study of Supercritical Flow Payload for Extravehicular Mounting on TZ-6

This paper provides a detailed description of the development and experimental results of the supercritical flow experiment payload carried on the TZ-6 cargo spacecraft, as well as a systematic verification of the out-of-cabin deployment experiment. The technical and engineering indicators of the payload deployment experiment are analyzed, and the functional modules of the payload are shown. The paper provides a detailed description of the design, installation location, size, weight, temperature, illumination, pressure, radiation, control, command reception, telemetry data, downlink data, and experimental procedures for the out-of-cabin payload in the extreme conditions of space. The paper presents the annular liquid surface state and temperature oscillation signals obtained from the space experiment and conducts ground matching experiments to verify the results, providing scientific references for the design and condition setting of space experiments and comparisons for the experimental results to obtain the flow field structure under supercritical conditions. The paper provides a specific summary and discussion of the space fluid science experiment project, providing useful references for future long-term in-orbit scientific research using cargo spacecraft.

Application of Multiple Linear Regression Method in Steel Column Design under Combined Loading

The article explores using multiple linear regression (MLR) approach to predict the cross-section of beam-column steel members. These members are complex in design, as they must withstand bending and axial forces. The design process involves multiple safety checks according to design standards. The first step in the design procedure is to calculate and verify the axial capacity of the member. Following that, the flexural capacity is calculated. Finally, the combined load capacity is examined, often involving a trial-and-error process. If the initially selected section cannot withstand the applied forces, a new section must be chosen, and the calculations must be repeated. This study employs a multiple linear regression approach to investigate the relationship between member properties (such as length and cross-section) and load design parameters (axial and bending forces). The primary objective is to predict the beam-column steel member’s elastic section modulus (Sx). The regression equation derived from the study is as follows: Sx = 18.000L + 6.839Pr + 47.193Mr – 129.093, with an R-square value of 0.985. The histogram of the equation exhibits symmetry and a standard distribution, while the typical probability plot demonstrates a relatively linear trend. Two examples are presented to evaluate the efficiency of the regression equation. The first example confirms the efficiency of the equation by determining the cross-sectional size by employing the regression equation and using it to verify the safety according to EIT design standards. The second example is the application of the equation for estimating the size of other types of steel members. This study suggests that the regression equation can effectively predict the size of beam-column steel members, providing reliable results for practical design applications.

Multidimensional RF pulse design with consideration of concomitant field effects.

To develop a small-tip multidimensional RF pulse design procedure that incorporates linear time-invariant gradient imperfections and concomitant field effects. This could be particularly important for contemporary low-field MRI systems with high-performance gradients. We developed an extension of the small-tip excitation k-space formalism, where concomitant fields were approximated as a Bloch-Siegert shift in the rotating frame. This was evaluated using realistic simulations of 2D selective excitation at various field strengths (0.2T, 0.55T, 1.5T, 3T, and 7T) with single and parallel transmit. Simulated excitation profiles from the original and extended k-space formalisms were compared. Experimental validations were performed at 0.55T with a single-channel transmit. The extended formalism provides improved 2D excitation profiles in all scenarios simulated, compared against the original formalism. The proposed method corrects the concomitant field effects on 2D selective excitations for B0 > 0.2T when the magnitude of the B0 is far larger than that of nonrotating concomitant fields. Simulation and phantom experiments at 0.55T match well for both original and proposed methods, with the proposed method providing sharper and more accurate excitation profiles at off-isocenter distances up to 15 cm. The impact of the proposed method is greatest in scenarios where concomitant fields are substantial, such as low field strengths and off-isocenter. Concomitant fields can be modeled as a Bloch-Siegert shift in the rotating frame during multidimensional RF pulse design, resulting in improved excitation profiles with sharp edges. This is important to consider for off-isocenter excitations and imaging at low field strengths with strong gradients.

Design and Experimental Validation of a High-Efficiency Sequential Load Modulated Balanced Amplifier

The purpose of this paper is to present a detailed design procedure for a highly efficient sequential load-modulated balanced amplifier (SLMBA) to provide an in-depth analysis of this complex power amplifier (PA) architecture. SLMBA’s basic theory is presented and discussed. An SLMBA with a frequency range from 2.45 GHz to 2.65 GHz was implemented and then measured in order to validate the proposed design methodology. In both saturation and back-off states, the fabricated SLMBA exhibits extremely high efficiency and output power. It delivers a maximum output power of 43~44.4 dBm and a drain efficiency (DE) of 71.6~75% at saturation, a DE of 63.5~66% at 6 dB output back-off (OBO) state, a DE of 61.8~66% at 10 dB OBO state, and a DE of more than 51% at 12 dB OBO state in the targeted frequency band. The achieved results demonstrate the effectiveness of the proposed design procedure.

Monitor-based synthesis in enforcing disjunctive generalised mutual exclusion constraints

This paper focuses on enforcing disjunctive generalised mutual exclusion constraints, referred to as OR-GMEC, on Petri net models. In this case, the legal marking set is non-convex, while the admissible marking set can either be convex or non-convex. The study presents a necessary condition for the existence of a monitor-based solution for a non-convex admissible marking set. Subsequently, the disjunctive constraints are developed to derive an optimal supervisory controller, and an algorithm is proposed for solution computation. The design procedure includes off-line computation mechanisms, yielding an optimal (maximally permissive) supervisor with only a few monitors. The key advantage of the suggested approach is that, unlike the current techniques, the number of monitors in the supervisor’s structure does not rise as the number of constraints increases.

Optimized Nonlinear PID Control for Maximum Power Point Tracking in PV Systems Using Particle Swarm Optimization

This paper proposes a high-performing, hybrid method for Maximum Power Point Tracking (MPPT) in photovoltaic (PV) systems. The approach is based on an intelligent Nonlinear Discrete Proportional–Integral–Derivative (N-DPID) controller with the Perturb and Observe (P&O) method. The feedback gains derived are optimized by a metaheuristic algorithm called Particle Swarm Optimization (PSO). The proposed methods appear to present adequate solutions to overcome the drawbacks of existing methods despite various weather conditions considered in the analysis, providing a robust solution for dynamic environmental conditions. The results showed better performance and accuracy compared to those encountered in the literature. We also recall that this technique provides a systematic design procedure in the search for the MPPT in photovoltaic (PV) systems that has not yet been documented in the literature to the best of our knowledge.

A new similarity method for the ultimate strength of box girders subjected to the combined load of bending and lateral pressure

The ultimate strength is an important property for hull structures nowadays. For large-scale structures, scale models are needed to perform physical model tests. Therefore, similarity methods are especially important. Traditional similarity methods consider similarity criteria of cross-section properties, and modern similarity methods introduce some strength-related similarity criteria to consider the nonlinear collapse procedure. However, these two kinds of criteria may be conflicting and are hard to meet simultaneously. Most existing works concentrated on simple structures, like stiffened plates, due to the difficulty in meeting all the similarity criteria. In this paper, a new similarity method is proposed for box girders subjected to the combined load of bending moment and lateral pressure. The proposed method considers only the strength-related similarity criteria, ignoring the criteria of cross-section properties. The column slenderness, the plate slenderness, and the torsional slenderness are selected as the similarity parameters for every stiffened plate in the box girder. The new similarity relations of the ultimate moment and the applied lateral pressure are derived according to the proposed criteria. A structured step-by-step scale model design procedure is proposed to design corresponding scale models. 4 numerical examples are presented to show the correctness and advantages of the proposed method.

Water holding capacity, aggregation, respiration, and chemical character of acid soil amended rice straw biochar enriched with different volumes of liquid extract (sap) of Kappapychus alvarezii

The quality of acidic soil is determined by organic C content produced from rice straw biochar in agriculture. In this context, liquid extract from Kappapychus alvarezii (K-sap) is used as a biochar enrichment agent. Therefore, this research aimed to (i) analyze the character of K-sap enriched rice straw biochar with different volumes, as well as (ii) evaluate the impact on soil water holding capacity, size class distribution, aggregate stability index, respiration rate, and acidic soil chemical characters. The treatment tested was the volume of K-sap kg-1 biochar, namely (i) without biochar, (ii) 0 mL, (iii) 500 mL, (iv) 1,000 mL, and (v) 1,500 mL. Each treatment was repeated three times and placed according to a randomized block design procedure. The area covered by K-sap, pore size, and amorphous degree increased while the pore volume of the biochar surface decreased. The addition of 1,000 mL of K-sap kg-1 biochar released a new peak number associated with the aliphatic and aromatic groups. The K-sap enriched biochar increased the proportion of soil aggregate size of 1-2 mm, water holding capacity, carbon storage, pH, total N, available P and K, exchangeable base cations as well as base saturation. Meanwhile, the concentration of Al3+ and H+ were decreased in the acidic soil solution. The results showed that the performance of rice straw biochar, K-sap volumes, soil chemical quality, water holding capacity, and ability to store carbon of the acidic soil was improved by adding K-sap volume.

Action of liquid tune mass dampers and base isolation in high rise buildings

In areas where earthquakes are common, high-rise structure seismic resistance is a major concern. The purpose of this research is to determine whether base isolation and liquid tuned mass dampers (LTMDs) can improve tall building seismic performance. A symmetrical G+8 story RCC structure in Zone V with medium grade soil is analyzed using ETABS software, Response Spectrum Analysis, and Equivalent Static Analysis to see how the structure behaves under different load combinations. For various structural configure rations, including basic models, models with water tanks, and models with base isolation, key factors such joint displacement, storey drift, base shear, and time period are evaluated. The results show that as compared to baseline models, models with damping and isolation systems exhibit much lower joint displacements, base shear forces, and story drift. In particular, base isolation models perform better in terms of reducing structural deformations and resisting lateral forces. Furthermore, shorter time periods and higher frequencies are routinely observed in base isolated models, suggesting enhanced dynamic response and energy dissipation capabilities. The paper also covers the flexibility and benefits of using LTMDs and base isolation to reduce seismic threats. Buildings can be successfully separated from ground motion by base isolation systems, and dynamic response can be countered by LTMDs using regulated liquid sloshing. The attraction of LTMDs in improving overall stability is increased by their adaptability in minimizing torsional and lateral vibrations. The study concludes by emphasizing how crucial it is to use cutting-edge structural retrofitting methods, including base isolation and LTMDs, to improve the seismic resistance of high-rise structures. In earthquake-prone areas, engineers and legislators may proactively protect tall buildings and guarantee a safer, more robust built environment by incorporating these technologies into construction standards and design procedures.

Design of Stabilizing Network for Capacitive Power Transfer Transmitter Operating at Maximum Power Transfer Limiting the Voltage Gain in Resonant Capacitors

Capacitive power transfer (CPT) is a technology that is emerging as an alternative to inductive power transfer (IPT) in applications requiring low to medium power. A great interest has been developed in the implementation of CPT systems in battery charging systems, where a condition to compete with IPT systems is the need to increase the power transfer in the CPT systems without significant losses. This paper puts forth a design methodology for a stabilizing network, which has been applied to a CPT system. This methodology has been developed through impedance analysis of the circuit, in order to achieve maximum power transfer, with total gains of voltage and current reaching a value close to unity. The methodology allows for the calculation of the value of the components of the stabilizing network, which has been designed with the objective of stabilizing the resonant frequency against changes in the capacitance of the transmission plates. To validate the design procedure, an experimental prototype was developed at 25 W and an operational frequency of 1.55 MHz. The results obtained validate the design methodology.

Pixelated slot-based dual-broadband tunable graphene metasurface absorber design through excitation of coupled modes in terahertz regime

This work presents a dual-broadband metasurface absorber (DBMSA) design inspired by the pixel-based slot patterning of the top graphene sheet (Gpat). Complimentary design procedure using slots ensures an inbuilt DC connection among graphene patterns, which makes tuning of chemical potential μc highly practical. A DBMSA provides an absorptivity (Af) ≥ 90 % from 4.46 to 5.6 THz (22.66 %) in the lower band and from 7.52 to 8.68 THz (14.32 %) in the upper band. At the same time, variation in μc (Top) from 0.5 to 1 eV leads to the coverage of an ultra-wideband (UWB) terahertz (THz) spectrum from 3.62 to 9.1 THz with Af≥ 90 % due to the overlapping of bands. The absorber is polarization-insensitive due to the symmetricity in the design of the unit cell and provides stable Af for incidence angle ≤ 60° under both transverse magnetic and electric polarization. The DBMSA is compact and ultra-thin, having periodicity and thickness of λ0/6.72 and λ0/26.9, respectively. The developed ECM model closely predicts the working principle of the metasurface. In conclusion, the proposed DBMSA can be used for several applications in the THz gap regime, such as THz shielding, radar cross-section (RCS) reduction, sensing, imaging, etc.

Behaviour of large-diameter high-strength bolted shear connections for prefabricated composite beams

This paper presents an experimental investigation into the structural behaviour of a new proposed shear connection incorporating high-strength large-diameter steel bolts in conjunction with steel fibre reinforced concrete blocks. A detailed account of fourteen large-scale push-out tests is provided with the aim of examining and quantifying the full deformational characteristics of these shear connections. The results include the load-slippage responses, shear resistances, and failure modes for the various specimens. It is shown that the proposed connection configuration is suitable for prefabricated composite beams in highway bridges and can be detailed to provide high stiffness over 1500 kN/mm, large shear resistance exceeding 1000 kN, and slippage at failure greater than 6.0 mm. The proposed connection can also be easily assembled on site and provides significant resistance against pull-out forces. Based on the experimental results, complementary design procedures are proposed to enable a prediction of the shear resistance of the connections. A simplified load-slippage relationship for the shear connections is also suggested and shown to represent closely the full deformation characteristics. Overall, the proposed shear connection configuration is shown to offer considerable stiffness, resistance, and ductility, and can be readily installed on site for joining steel beams and precast slabs in combination with high performance in-situ concrete. This connection form contributes to an enabling construction technology for promoting effective prefabrication of composite bridge structures.

A Novel MARS-Based Design Procedure for Anchored Wall Systems in Urban Excavations

A Novel MARS-Based Design Procedure for Anchored Wall Systems in Urban Excavations

An improved flexural design procedure of steel plate I‐girders considering elastic lateral torsional buckling at elevated temperatures

AbstractIn the present study, an improved design method is proposed for the flexural design of steel plate I‐girders at elevated temperatures. The proposed method accounts for two important phenomena accompanying the temperature increase in steel I‐girders: (1) alteration of the failure mode and (2) degradation of the material properties. The main strategy of the proposed procedure is to find the ambient‐temperature‐equivalent design parameters of steel I‐girders at elevated temperatures. The basic design relationships are adopted from the flexural design provisions of AISC 360‐16 and then modified to accommodate the elevated temperatures and instability conditions of I‐girders. To evaluate the accuracy and efficiency of the proposed method, a comprehensive finite element study is conducted using ABAQUS. To this aim, 54 numerical models of steel plate I‐girders with different cross‐section slenderness parameters were investigated. All the simulated I‐girders were prone to fail in elastic lateral‐torsional buckling mode at both ambient temperature and elevated temperatures. To corroborate the numerical modeling and analysis process at ambient and elevated temperatures, the results were verified against the available experimental data. Based on the results, the maximum absolute deviation of the ultimate flexural strength obtained from the proposed method from the finite element predictions was 9%.

From CAD to representations suitable for isogeometric analysis: a complete pipeline

AbstractNext generation CAD/CAE systems shall integrate design and analysis procedures as a means to simplify workflows, boost performance, and speed up time to market. In the present paper we demonstrate a proof of concept of such a unification using subdivision surfaces and the enabling technology of isogeometric analysis. In particular, we present a complete pipeline to convert CAD models into smooth $$G^1$$ G 1 spline representations, which are suitable for isogeometric analysis. Starting from a CAD boundary representation of a mechanical object, we perform an automatic control cage extraction by means of quadrangular faces, such that its limit Catmull-Clark subdivision surface approximates accurately the input model. We then compute a basis of the $$G^1$$ G 1 spline space over the quad mesh in order to carry out least squares fitting over a point cloud, acquired by sampling the original CAD geometry. The resulting surface is a collection of Bézier patches with $$G^1$$ G 1 regularity. Finally, we use the basis functions to perform isogeometric analysis simulations of realistic PDEs on the reconstructed $$G^1$$ G 1 model. The quality of the construction is demonstrated via several numerical examples performed on a collection of CAD objects presenting various challenging realistic shapes.

Optimizing multivariate alarm systems: A study on joint false alarm rate, and joint missed alarm rate using linear programming technique

In modern complex industrial systems, multiple process variables interact with one another. The role of alarm systems in ensuring the safety of these systems is of utmost importance. Consequently, there is an increasing value placed on the assessment of the performance of multivariate alarm systems. As the dimensions of the system and the number of variables grow, designing optimal parameters for the multivariate alarm system using traditional approaches such as probability density function estimation becomes increasingly convoluted. In this paper, an approximate method is proposed for calculating two indices known as the Joint False Alarm Rate (JFAR) and Joint Missed Alarm Rate (JMAR), which are used to evaluate the performance of multivariate alarm systems. These indices are computed using the multivariate Markov chain method. The Markov chain is constructed by solving an optimal Linear Programming (LP) problem. Subsequently, joint indices are defined based on steady state estimations of a multivariate Markov chain. To validate the theoretical results obtained on the JFAR and JMAR and to demonstrate the proposed performance assessment and alarm system design procedures, numerical example and an industrial case study are provided.

Axial Flow Fan Performance in a Forced Draught Air-Cooled Heat Exchanger for a Supercritical Carbon Dioxide Brayton Cycle

Abstract An axial flow cooling fan has been designed for use in a concentrated solar power plant. The plant is based on a supercritical carbon dioxide (sCO2) Brayton cycle, and uses a forced draft air-cooled heat exchanger (ACHE) for cooling. The fan performance has been investigated using both computational fluid dynamics (CFD) and scaled fan tests. This paper presents a CFD model that integrates the fan with the heat exchanger. The objective is to establish a foundation for similar models and to contribute to the development of efficient ACHE units designed for sCO2 power cycles. The finned-tube bundle is simplified, with a Porous Media Model representing the pressure drop through the bundle. Pressure inlet and -outlet boundary conditions are used, meaning the air flowrate is solved based on the fan and tube bundle interaction. The flowrate predicted by the CFD model is 0.5% higher than the analytical prediction, and 3.6% lower than the design value, demonstrating that the assumptions used in the design procedure are reasonable. The plenum height is also found to affect the flowrate, with shorter plenums resulting in higher flow rates and fan efficiencies, and longer plenums resulting in more uniform cooling air flow.

Surface Disinfection Systems with UV-C Lamps – Verification Measurements and Design Procedure Proposal

ABSTRACT Ultraviolet radiation in the UV-C range is widely applied to disinfect surfaces, air, and water. UV-C (germicidal) lamps are commonly used, and their application is reliable, scientifically proven, and efficient to inactivate various types of bacteria, viruses, and fungal spores, including the SARS-CoV-2 virus. This research aims to develop a UV-C irradiance design procedure for germicidal devices disinfecting surfaces in rooms. This procedure considers the required values of UV-C radiation doses that disinfect rooms efficiently. For this purpose, it has been proposed to apply the DIALux evo software to design the appropriate UV-C irradiance on disinfected room surfaces using different germicidal devices. The measurements verified the accuracy of the simulation performed in the DIALux evo software, which also considered the reflection of the ultraviolet radiation from the principal planes of the room. Two rooms with different dimensions were selected to verify the computational accuracy of the developed design procedure for the disinfection system. Ultraviolet lamps were placed in the rooms, and irradiance measurements were taken at the selected measuring points. The results of the irradiance measurements were compared. The comparative analysis of the disinfection device proved that it was possible to adapt the DIALux evo software to make the calculations for designing room disinfection systems. The research made it possible to determine a suitable design procedure for surface disinfection systems, which prevents errors in proper surface disinfection after implementing UV-C lamps in the room.

Design procedure of reach stacker control system

Reach stackers are efficient and maneuverable machinery for an overload of overall containers in cargo terminals and ports today. Such machinery design determines the practical interest of the engineering industry specialists. However, the lack of information in open sources about structural or kinematic diagrams of equipment control mechanisms and recommendations for their calculation does not allow an effective approach to the creation and update of reach stackers. We developed the design procedure of the reach stacker control system, which considers the kinematic and geometric parameters of the container spreader, as a result of the conducted research. It can be used in the design stages of mechanisms for spreader lateral displacement, extension of the spreader sections, spreader inclination in the vertical plane, container fixation by spreader, spreader rotation, lifting-lowering and telescoping of the boom, as well as during the real operation modes of reach stackers in cargo terminals and ports.

H∞ optimum design and nonlinear seismic performance assessment of tuned-mass-damper-inerter (TMDI) supported by an auxiliary structure

Tuned Mass Damper Inerter (TMDI) and its simplified form, Tuned Inerter Damper (TID), are highly effective in mitigating seismic responses in buildings, particularly when rigidly connected to the ground. However, practical constraints often limit the feasibility of this ideal setup. This study introduces a novel configuration: the AS-type TMDI, which connects the TMDI to an auxiliary structure (AS) adjacent to the main building to simulate a ground connection. To design the AS-type TMDI, this research builds upon insights from studies on TMDIs in adjacent buildings and develops an analogous 3-DOF model representing the TMDI-linked adjacent-building system. This model incorporates two buildings of different heights, allowing the TMDI to be connected at any floor level. Utilizing fixed-point theory, the study derives an analytical solution for the optimal design of TMDI systems within this novel configuration. Additionally, a method is introduced to determine the optimal stiffness and design procedure for the AS itself. The performance of the proposed AS-type TMDI is evaluated through comprehensive nonlinear seismic analysis of a benchmark nine-story steel frame structure, accounting for material and geometric nonlinearities. Results demonstrate that the AS-type TMDI performs comparably to a virtually grounded TMDI in effectively reducing the seismic responses. Furthermore, this innovative configuration outperforms both a conventional retrofitting technique, where the building is rigidly connected to the AS, and a system where a viscous damper alone connects the main building to the AS. This highlights the AS-type TMDI's potential to significantly improve the building’s seismic performance.