Bus Structure Research Articles

Aerodynamic evaluation of a commercial bus structure

Abstract This article focuses on the aerodynamics evaluation of a commercial intercity bus used on the highway. The research begins with a brief introduction to the state-of-the-art vehicle aerodynamic assessment using the iterative CFD (computational fluid dynamics) method. The second part presented the method to generate the basic CAD model of a commercial bus using the blueprint images. The boundary conditions and the discretization of computational volume are presented in the third part of this document. The aerodynamic evaluation is performed at a velocity of 33.34 m/s, highlighting the velocity distribution around the bus structure and the air pressure on the bus and road surface. For high accuracy of the simulation results, a movable road surface and a rotation zone is introduced around the wheels, according to the simulation case. After analysing the results of the original model is proposed a geometrical improvement by adding the air deflectors to the bus model. The improved bus model is simulated under the same boundary conditions as the base model. The last part of the document presents the comparison study and its conclusions.

6σ Robust Lightweight Design of the GIL/GIS Bus Based on Co‐Simulation of Insulation, Current Flow, and Mechanical Stress

GIL/GIS bus is widely used in the field of power transmission and distribution, and the demand for lightweight is becoming more and more prominent. To reduce the weight of the bus and ensure the safety and reliability of the structure, a new 6σ robust design method of the GIL/GIS bus based on electric‐thermal‐mechanical co‐simulation is proposed. Taking a 550 kV/5000A bus as the initial structure, considering the uncertainty of product size and performance, a 6σ robust lightweight model of bus insulation electric field strength, current temperature rise, and mechanical stress multi‐performance co‐simulation is established. The finite element numerical calculation method is used to calculate and analyze the performance parameters of the bus. The Kriging surrogate model is used to form the response surface, and the optimal bus structure is obtained by genetic algorithm. The results show that after the robustness optimization, the performance of the bus meets the design requirements, the weight per meter decreased from 65.11 to 39.12 kg, and the lightweight effect is remarkable. Compared with the traditional deterministic optimization design, the reliability of the structure is improved. The new method of the GIL/GIS bus lightweight design proposed in this study has high feasibility and application prospects, which can provide new ideas for the development of gas‐insulated electrical equipment. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Prediction of full-scale crashworthiness performance based on component-level testing: application to bus structures

The growing interest in vehicle crashworthiness necessitates efficient methods to predict full-scale crash performance from component-level testing. This study introduces a framework for predicting vehicle crashworthiness using component-level tests. The framework employs a scaling procedure incorporating factors like total energy, deformation mode, and vehicle dimensions. The feasibility of this method was validated both experimentally and numerically in a study on the rollover performance of paratransit buses, utilizing two decades of data from full-scale and component testing of six buses. Wall-to-floor connections, prone to plastic deformation during rollovers, were tested for component bending. A rollover performance index was developed as a scaling procedure, establishing a clear correlation between full-scale and component tests. Additionally, extensive finite element simulations confirmed the framework applicability to numerical simulations, demonstrating its practical use in vehicle crashworthiness evaluations to foster resource-efficient design and reduce dependence on full-scale tests.

Should Islamic Window be converted into a Full-Fledge Islamic Bank? A case study in Indonesia

Research Originality: This research provides fresh perspectives on the future landscape of Islamic banking, particularly concerning the Islamic window. The paper stands out for its originality as it undertakes an empirical study utilizing a mixed method. This study is also expected to answer the research gap between literature studies, empirical studies, and implemented policies. Additionally, it is driven by the objective of contributing to the existing literature on Islamic finance.Research Objectives: This study dives into whether converting Islamic Business Units (UUS) into full-fledged Islamic Banks (BUS) leads to performance enhancement.Research Methods: There are two types of data analysis methods, namely qualitative and quantitative. The qualitative analysis method comes from a collection of literature reviews and institutional opinions from Islamic banking experts in the world. This study employs a multi-pronged quantitative approach to investigate the performance and consumer perception of Islamic banking services with an emphasis on UUS and BUS.Empirical Result: The results indicate that UUS and BUS structures adhere to Sharia principles and achieve commendable performance. However, analysis of financial reports across many countries, including Indonesia, shows that UUS's financial performance is generally better than BUS. The research further emphasizes that internal factors like capital adequacy, asset quality, and management capabilities, rather than the institutional structure itself, hold greater sway in driving performance improvement. Forced conversion of UUS could even hinder overall progress. Implications: Beyond financial considerations, the study explores consumer behavior through surveys with educated individuals. The results indicate that their choice between BUS and UUS products is guided by practical factors such as financial returns, costs, and service reliability offered by each structure. JEL Classification: G21, G28 How to Cite:Abimanyu, A., & At Tamimi, R. A. (2024). Should Islamic Window be Converted into a Full-Fledge Islamic Bank? A Case Study in Indonesia. Etikonomi, 23(1), 183 – 200. https://doi.org/10.15408/etk.v23i1.35082.

Radiated emission from DC bus loop of AC induction motor inverter FEM based and experimental evaluation

The paper describes practical method how to analyze locally radiated magnetic field to improve the geometry of printed circuit board (PCB) or busbar structure, select better control method and design electromagnetic interference (EMI) filter. Experimental prototype of three-phase induction motor variable frequency drive has been created and controlled by microcontroller with sinusoidal, namely pulse with modulation (PWM) method. Three-dimensional finite element model simulation of DC bus structure has been created and results has been obtained. Electromagnetic field was measured, practically and results compared with simulation-based ones. Simulation based and experimental results matches thus allowing to conclude method usefulness for cost effective way to test different geometries of DC bus, different modulation methods, EMI filters for variable frequency drive, and other power electronics converters.

Analysis and Design of Independent DC Bus Structure Multiport Power Electronic Transformer Based on Maximum Power Transmission Capability of Low-Voltage DC Ports

Owing to the diverse connection configurations of dual active bridge converters, a multiplicity of low-voltage DC port structures are anticipated to emerge in the independent DC bus structure multiport power electronic transformer (IDBS-MPET). An inadequate low-voltage DC port structure exacerbates the power imbalance in IDBS-MPET, presenting a risk of overmodulation even when transmitting relatively low levels of power. To overcome this limitation, a design scheme of IDBS-MPET topology based on the maximum power transmission capability of the low-voltage DC ports is proposed in this paper. Three topology design rules are derived from the maximum power transmission capability results of more than 80 typical IDBS-MPET topologies. The symmetrical triple cross-phase connection structure, the symmetrical double cross-phase connection structure and the single-phase connection structure are sequentially identified as the three most optimal structures of low-voltage DC ports. By employing the proposed design methodology, each low-voltage DC port achieves its maximum power transfer capability relative to other configurations. The effectiveness of the proposed design scheme is validated by an optimal designed IDBS-MPET topology with six low-voltage DC ports.

Development of the Construction of City Buses in Terms of Reducing the Curb Weight of the Vehicle

Modern city buses are made of various construction materials and the share of material groups has changed over the decades. By replacing heavy materials for structural elements or bus components with their lighter counterparts, the kerb weight of the bus can be reduced by up to several hundred kilograms. This article presents the issues of the development of city bus design in terms of passenger space comfort and bus structure in the context of reducing the vehicle's own weight since the 1970s. The main changes in vehicle design allowing for reducing the weight of structural elements of bodies and chassis as well as the main assemblies in city buses are presented as well as research on body types in terms of aerodynamics, safety and travel comfort. It has been shown that reducing the weight of the bus does not negatively affect its load capacity and the new bus designs are equipped with safety and comfort systems, including ABS (Anti-lock Braking System), ASR (Automatic Stability Regulation), ESP (Electronic Stability Program) and air conditioning in the passenger space. Thanks to modern light construction materials, we gain the opportunity to improve safety and comfort without losing the transport capabilities developed as a result of the development of city buses over the years.

Determining optimal paths of virtual links in Avionics Full-Duplex Switched Ethernet networks using modified ant colony optimization algorithm

The Aeronautical Radio Incorporated (ARINC) 664 Avionics Full Duplex Switched Ethernet (AFDX) data bus has been developed based on the Ethernet standard Institute of Electrical and Electronics Engineers (IEEE) 802.3, including redundancy, guaranteed bandwidth, and deterministic timing of transmit interval time to meet the increasing amounts of data exchange needs among aircraft equipment while reducing the harness weight. Isolated data tunnels, called Virtual Links (VLs), are established to route Ethernet frames from a single source to one or more destinations using end systems and switches that contain a static routing mechanism specific to ARINC 664 AFDX. A limited number of algorithmic approaches are presented in the literature to route VLs; however, they are proven in uncomplicated topologies. Depending on the technological development, the node amount consisting of End Systems (ESs), Switches, and Remote Data Concentrators (RDCs) in the aircraft data bus structure will increase enormously. Bandwidth utilization (BWU), bandwidth flexibility limit for further extensions, port usage, total harness weight, latency, and redundancy should be considered in addition to number of nodes to determine VLs’ route paths in ARINC 664 AFDX networks. In such cases, determining optimal paths of VLs in ARINC 664 AFDX networks becomes a challenging problem to solve with the existing methods in the literature. This paper proposes an Ant Colony Optimization (ACO) based algorithm to determine optimal VL path routes in the complex topology of ARINC 664 AFDX networks considering multi-effective parameters. Experimental simulations are executed to confirm the validity of the presented algorithm in different case studies and show its applicability in the industry. The obtained results of the proposed algorithm outperform conventional algorithms existing in the literature in terms of bandwidth usage depending on predefined expansion capacity and solution time. The proposed algorithm also introduces novelty by considering the redundancy, total harness weight, and delay limit, which is deficient in the existing literature.

Development of a Neural Network Model and Taguchi-Based Optimization for Dry Sliding Wear Performance of Al 6065 Alloy Reinforced with Nano SiC and Graphene Nanoplatelets

The Al6065 alloy is widely used in various applications, including tubing for furniture, railway and bus structures, pylons, platforms, and pipelines. However, due to the wear experienced in these applications, it is essential to enhance the wear confrontation of this alloy. To address this issue, this research focuses on reinforcing Al6065 with nanoparticles of silicon carbide and graphene by means of the stir casting method. The wear behaviour of the alloy is studied by varying the rotational speed, load, and composition of reinforcement in the stir casting machine using Taguchi design of experiment. The rate of wear and friction coefficient are measured as responses. The obtained results are then analysed and optimized for the minimum of the output responses using S/N ratio analysis. Further, ANOVA is carried out to determine the influence of each parameter, and a model of the neural network is developed to predict the response. The findings indicate that cumulative the percentage of reinforcement enhances the wear resistance of the alloy. The optimized values of the rotational speed, load, and composition of reinforcement lead to improved wear resistance, with a corresponding decrease in the coefficient of friction. The ANOVA results reveal that the rotational speed and load significantly affect the responses, while the reinforcement composition has a moderate effect. The developed neural network model accurately predicts the response with a high degree of accuracy. The model can be used to optimize the wear behaviour of Al6065 alloy reinforced with nanoparticles of silicon carbide and graphene, as well as for prediction of the alloy's wear behaviour in various application environments. In conclusion, this research delivers a complete thoughtful of the wear behaviour of Al6065 alloy reinforced with nanoparticles of silicon carbide and graphene. The findings can be used to optimize the wear resistance and improve the routine of this alloy in various applications.

Slew Maneuver Constraints for Agile Flexible Spacecraft

Traditional spacecraft design paradigms rely on stiff bus structures with comparatively flexible appendages. More recent trends, however, trade deployed stiffness for packaging efficiency to stow apertures with larger areas inside existing launch vehicles. By leveraging recent advances in materials and structures, these spacecraft may be up to several orders of magnitude lighter and more flexible than the current state of the art. Motivated by the goal of achieving agility despite structural flexibility, this paper proposes and verifies a quantitative method for determining structure-based performance limits for maneuvering flexible spacecraft. The results demonstrate that, contrary to common assumptions, other constraints impose more restrictive limits on maneuverability than the dynamics of the structure. In particular, it is shown that an attitude control system’s available angular momentum and torque are often significantly more limiting than the compliance of the structure. Consequently, these results suggest that there is an opportunity to design less-conservative, higher-performance space systems that can either be maneuvered faster (assuming suitable actuators are available) or built using lighter-weight, less-stiff architectures that move the structure-based performance limits closer to those of the rest of the system.

Topology of Wind Power DC Collection Converter Based on Double Bus Structure and Its Power Balancing Control Strategy

Wind power collection technology is the key to grid-connected wind power generation. Compared with AC wind integration, DC wind power collection is more advantageous. Using a triple active bridge (TAB) converter as a submodule, this paper proposes a wind power DC converter topology and its control strategy for medium-voltage dc (MVDC) grid connection. The converter adopts a double bus structure, with the MVDC bus connected to the grid and the low-voltage dc (LVDC) bus handling the mismatched power. It has independent maximum power point tracking (MPPT) control, power balancing, and autonomous voltage balancing on the output side. The converter system is simulated and verified on the MATLAB/SIMULINK software platform. The simulation results show the effectiveness of the control strategy and the ability of the converter to operate stably under multiple conditions.

Design and Synthesis of AMBA APB Protocol for SoC

The AMBA (Advanced Microcontroller Bus Architecture) and APB (Advanced Peripheral Bus) protocol is a widely used bus protocol designed by ARM for integrating peripheral devices into a system-on- chip (SoC) design. It provides a low-power, low-complexity interface that allows efficient communication between the master and slave devices within the SoC. The APB protocol offers a straightforward and flexible architecture, making it suitable for a wide range of SoC applications. It supports a single-master, multiple-slave bus structure, where an APB master can communicate with multiple APB slave devices. This architecture enables seamless integration of various peripheral devices, such as timers, UARTs, I/O controllers, and more, into the SoC. One of the key advantages of the APB protocol is its power efficiency. It achieves this by utilizing a simplified set of signals and reduced complexity compared to other bus protocols. The APB bus operates based on a common clock signal, ensuring proper timing and synchronization of data transfers while minimizing power consumption.

Congestion Management of Power Systems by Optimal Allocation of FACTS devices using Hybrid Techniques

For system operators, Congestion management is a difficult task as the market’s security and reliability are protected by this methodology. As the magnitude of an electric transmission system is extremely dynamic, limits must be estimated much beforehand, in order to manage the congestion issues at the right time. Flexible AC transmission systems (FACTS) are used to control voltage fluctuation by adjusting the system's real and reactive power. A combination of Improved Remora Optimization (IRO) and Improved Radial Basis Function (IRBF) is used to allocate positions and sizes of the FACTS devices. In this study, Static Synchronous Compensator (STATCOM), Interlink Power Flow Controllers (IPFC) and Unified Power Flow Controllers (UPFC) are among the FACTS devices used. In the proposed hybrid IRO-IRBF technique, following are the functional aims calculated: build-on-expenditure, Line Loading (LL), Total Voltage Deviation (TVD) and real power loss. Additionally, the hybrid IRO-IRBF technique is used to confirm the proper location using the IEEE 30 bus structure. TVD, power loss, installation costs, and line loading are the measurements used to assess the implementation performance of the hybrid IRO-IRBF approach. From the result analysis, the hybrid IRO-IRBF achieved a real power loss of 0.1591 p.u., and TVD of 0.02 p.u., which is lesser than the existing Whale Optimization Algorithm and Mayfly Optimization Algorithm.

Higher-order modeling of a thin-walled beam with a welded multicell cross-section and its application to welding line optimization

Thin-walled multicell structures observed in vehicle frames are partially welded to lower the welding process cost while maintaining their overall structural stiffness comparable to those of fully-welded multicell structures. A fast and reliable beam-based model for analyzing such structures is required in the concept stage of the design process. In this investigation, an analysis method for a thin-walled beam of a multi-cell cross-section partially welded along its axial direction is newly established using a higher-order beam theory (HoBT). Our approach uses the Lagrange multipliers to impose the partial welding condition along the common edges of multiple thin-walled closed sections using the three-dimensional field derived from a higher-order beam theory. The developed method in this study can be an accurate and effective alternative without full finite element analysis employing shell and solid elements. To find the optimal welding locations, we introduced binary design variables parameterized through their corresponding welding constraints to identify the status of welding or non-welding along a candidate welding line. A genetic algorithm is adopted to solve optimization problems. After establishing the analysis method and optimization technique, their validity was checked using double-cell and triple-cell sectioned beams and beam frame structures, including a bus structure. The stiffnesses of the structures with optimized partial welding lines (20%) drop less than 6% from those of fully welded counterparts.

Thermal Deformation Stability Optimization Design and Experiment of the Satellite Bus to Control the Laser Communication Load’s Acquisition Time

The optical axis angle fluctuation due to thermal deformation of the satellite bus between the laser communication load and the star sensor must be constrained to within 0.16 mrad to meet the rapid acquisition needs of the laser communication satellite. This paper analyzes the satellite’s in-orbit temperature field distribution, which is then used as the input boundary condition for the thermal deformation analysis. The optical axis angle fluctuation is reduced by the common reference optimization design. Then, adaptable isolation between the satellite bus structure and the reference support structure reduces the thermal deformation coupling. As a result, there will be less optical axis angle fluctuation caused by thermal deformation. The thermal deformation between the optimized laser communication load and the star sensor installation angle is decreased to 14.25″ according to the entire satellite simulation analysis of the modified structure. The maximum angle variation induced by temperature change dropped from 117.74″ to 10.72″ through the ground temperature deviation and prism calibration tests. The on-orbit alignment test confirms that the required capture time of 30 s is met. The aforementioned work minimizes the uncertain region of laser communication load, lessens the in-orbit acquisition time, and satisfies the demand for speedy acquisition.

Bounding Memory Access Times in Multi-Accelerator Architectures on FPGA SoCs

Modern FPGA System-on-Chips (SoCs) embed large FPGA logics capable of hosting multiple hardware accelerators. Typically, hardware accelerators require direct access to the shared DRAM memory for reaching the high performance demanded by modern applications. In commercial FPGA SoCs, this goal is achieved by interconnecting the hardware accelerators on an interconnect based on AMBA AXI, which is the de-facto industrial standard for on-chip communications. The AXI standard provides great flexibility in the definition of the network topology. Nevertheless, such flexibility generates a significant unpredictability when attempting to bound the hardware accelerators’ response time when executing under contention. This work focus on bounding the worst-case memory access time of hardware accelerators deployed on commercial FPGA SoCs. We propose a modeling and analysis technique to bound the response time of the hardware accelerators and evaluate the schedulability of a system applicable to arbitrary AXI-based bus structures deployed on FPGA SoCs. Our results are validated on real execution traces collected on two popular FPGA SoCs belonging to the Xilinx ZYNQ-7000 and Zynq-Ultrascale+ families and by simulated results.

RF and Crosstalk Characterization of Chip Interconnects Using Finite Element Method

This paper presents new finite element method (FEM) based approach for radio frequency (RF) and crosstalk (X talk) characterization of chip interconnects. Being based on scattering parameters (S-parameters), this approach truly and accurately demonstrates the transmission line behavior of chip interconnects over a wideband of frequencies. To demonstrate FEM based method, a single-line and a 3-line interconnect test structures on SiO2-Si substrate have been designed and simulated in High Frequency Structure Simulator (HFSS). The RF and crosstalk characterization of chip interconnect materials Copper (Cu), doped multilayer Graphene Nanoribbon (DMLGNR), and neutral multilayer Graphene Nanoribbon (NMLGNR) have been demonstrated in terms of transmission coefficient (Sij & Smn) from 1 to 1000 GHz. The single-line three-dimensional (3D) structures comprising of Cu, DMLGNR, and NMLGNR have maximum transmission loss values of -15.93 dB, -22.03 dB, and - 13.73 dB at frequencies of 643 GHz, 402 GHz, and 643 GHz, respectively whereas three-line bus structure exhibit maximum victim-line transmission loss values of -15.28 dB, -17.47 dB, and -15.98 dB at frequencies of 247 GHz, 829 GHz, and 377 GHz, respectively. Further, the crosstalk results have demonstrated that as frequency increases significant crosstalk is observed between nearby lines due to electromagnetic interference and coupling (EMI/EMC) issues.

Crashworthiness analysis and design of a sandwich composite electric bus structure under full frontal impact

The transition toward sustainable transportation includes adopting ecofriendly electric vehicles in public transport, which reduces greenhouse gas emissions and increases energy efficiency. One of the critical features in fuel economy improvement of electric vehicles lies in lightweight structural design. Nevertheless, the crashworthiness of the structures of the vehicles and the safety of passengers must be guaranteed in the attempt of mass reduction because the crash of large vehicles such as buses usually costs many lives. This paper, therefore, aims to present an in-depth analysis of the impact behavior of a lightweight monocoque sandwich composite microbus body under full-frontal crash conditions. The bus structure, made of a high-density polyurethane foam core and woven glass fabric-epoxy face sheets, was modeled and simulated via LS-DYNA dynamic analysis using strength-based Chang-Chang criteria to characterize the failure mechanism of the structure and investigate intrusion into the passenger survival space. Under front collision, the front panel, A-pillars, and front sidewalls of the original bus were found to be extensively damaged in the compressive fiber mode. Based on the 50th percentile male dummy anthropometric parameters, injury indices of 0-5 intervals were proposed to evaluate occupant injury risks. The maximum front and side intrusion into the specified safety space under a maximum impact speed of 50 km/h is 208 mm at the front panel and 221 mm at the sidewall, indicating high injury indices of 3.59 and 4.81, respectively. The effects of stiffeners reinforced in the front panel and foam core thicknesses in the sidewalls, floor, and bottom parts on crashworthiness improvement were thoroughly discussed. The improved bus design can significantly enhance the safety of the occupants with a minimal increase in structural weight of merely 35.6 kg. An effective vehicle safety design under full frontal collision is presented.

Partial discharge location method in GIS coaxial bus structure based on multi-normal photoelectric array

Partial discharge is an important reason for the failure of GIS equipment, and its detection can determine the type and position of the defect in GIS. In the discharge inspection, accurate positioning of defects can provide an important reference for maintenance. In response to this, this paper proposes a discharge optical location method based on multi-normal photoelectric array. Based on the SiPM sensor, a multi-normal array is designed and built into the coaxial structure of GIS equipment. Measuring the responses of each unit in the array to get the response ratio of each element and calculate the direction of the discharge light in space. This paper firstly introduces the array structure, and proposes a solution algorithm in space, which uses the proportional relationship of multi-normal elements to solve the discharge direction. Secondly, the feasibility and error source of this method are verified in the simulation software. Finally, the application effect of this method in actual power equipment is verified by actual measurement, and the results show that this method can accurately locate the partial discharge in GIS.

Assessment of Passenger Security in Paratransit Buses

The main objective of this study was to assess usefulness of 3-D, nonlinear dynamic, explicit computer codes for transit safety and security research. An analysis of response of a paratransit bus structure under loading caused by high explosive (HE) detonation is presented. It was assumed that the cubic HE charge detonates in the air near the bus. The ground was modeled as a rigid stationary wall. The problem was studied using LS DYNA, an explicit, 3-D, dynamic, nonlinear finite element program. The HE detonation and the processes of shock propagation in the air were modeled using the mesh with the Euler’s formulation. The Euler’s mesh was modeled as a rectangular prism sufficiently large enough to cover the entire bus structure. The nonreflecting boundary conditions on the top and side surfaces of the Euler’s domain and the sliding interface on the bottom side for the contact with the ground were assumed.A finite element model of the Ford Eldorado Aerotech 240 paratransit bus was developed for this study. This model consisted of 73,600 finite elements and had 174 defined properties (groups of elements with the same features) and 23 material models.Computational analysis provided useful information about dynamic deformations and damage inflicted to the bus structure under load blast wave activated by the HE detonation. It allowed for detailed, rigorous analyses of time histories of accelerations, velocities, deformations, and stresses. Resulting acceleration and overpressure histories were correlated with expected blast injuries of the bus passengers. The data obtained can be used to improve passenger safety and to reduce the threat of suicidal terrorist attacks against public transit. Changes in the bus structure and replacement of some materials to build a safer class of vehicles can be carefully considered and implemented.