System Design Requirements Research Articles

A Reliability Allocation Methodology for Mechanical Systems With Motion Mechanisms

The design requirement of a mechanical system with motion mechanisms is to ensure the successful implementation of its motion functions. Aiming at the characteristics of motion mechanisms, a reliability allocation methodology is proposed. Since motion reliability plays an important role in motion mechanisms, a system decomposition is extended to map motion functions with subsystems. Combined with the analytic hierarchy process model, the subsystem contribution factor is developed. For motion mechanisms, the nondestructive fault events that have a significant impact on motion reliability are considered in the potential reliability improvement factor. To assist in evaluating the criticality of failures, the transformed failure severity factor is utilized. In addition, the dynamic performance factor is developed to evaluate the motion performance of the systems. Then, due to the interactions between the subsystems, the copula theory is applied to investigate the failure dependence, and the reliability model of the system to be apportioned is established. Furthermore, an engineering case about a mechanical system of an aircraft is presented to illustrate the applicability and rationality of the proposed method. The result shows that the reliability allocated to the subsystems is decreased when the failure dependence is considered, which is more reasonable in engineering practice.

Design of Thermostat Controlled Electrical Heating Circuits on Manned Spacecraft

A thermostat is a type of contact inductive device. It has the features of being compact, lightweight, and high temperature control precision. A scheme for using a thermostat as a control device in the active electrical heating and temperature control circuit of the spacecraft is proposed. It is in line with the design requirement of the spacecraft thermal control system when the computer controlled heater-system is limited. Compared with the computer-controlled heater system, the thermostat-controlled heater system has the advantages of simple configuration, easy implementation, and high reliability under certain conditions. The thermal design of the shunt regulator, manipulator, portable light, and emergency brake device is analysed given the characteristics of the demands on manned spacecraft. The use of a thermostat to solve the temperature control problem when a computer is not available is a common feature of these thermal designs. The temperature results of the on-orbit test and ground test prove that using a thermostat in the heater system of spacecraft can ensure equipment is within the range of index requirement reliably.

Research and Verification on the Solution of Bleed Air Temperature Deviation of Civil Aircraft Pneumatic System

The pneumatic system of civil aircraft is equipped with a precooler (PCE) to cool the high-temperature bleed air from the engine to meet the design requirement of a downstream user system. The PCE is usually a fork-flow heat exchanger. This heat exchange structure will make the outlet temperature difference especially large, which shall lead to the deviation of the inlet air temperature of the downstream wing anti-icing system and air conditioning system and cause the temperature of bleed air supplied to the wing anti-ice system unstable. During a flight test of a certain large passenger aircraft, it was found that the bleed temperature at the PCE outlet was lower than the piccolo inlet temperature of the wing anti-ice system when the wing anti-ice system was operated with two engine bleed systems on. This paper creatively proposes design ideas for the three kinds of mixers and determines the solution of adding a mixer downstream of the PCE to solve the temperature deviation problem. The mixer is installed at the hot side outlet of the PCE and used to mix the temperature field at the PCE outlet so that the air supplied to the downstream customer systems meets the design temperature requirements. According to the simulation calculation and laboratory test verification results, the design scheme of a certain large passenger aircraft is selected, which has successfully solved the problem of temperature stratification at the outlet of the PCE and supported the follow-up flight test.

Research on Three-Port Converter for New Aerospace Energy Architecture

The traditional design method of spacecraft power systems based on customization and the combination of two-port converters can no longer meet the increasing application demands of having high power and being modular and versatile. Three-port DC converter, standardized to form a redundant parallel power supply system with a distributed model, is a possible solution to meet the design requirements of the above spacecraft power supply system. In this paper, a three-port converter is designed to complete the MPPT control of the PV array at the input end to maximize the power generated by the PV array, complete the battery charge and discharge control, realize the bidirectional conversion and transmission of the battery charge and discharge power, and complete the control of the load voltage at the output end to ensure the stable and reliable power supply of the load. If the integrated DC converter is used to realize the power transmission and conversion between the three ports at the same time, the volume and weight of the system can be greatly reduced, and then the power density of the system can be improved.

Simulation analysis and research of cylindrical lithium battery pack automation equipment system

The performance difference of the single battery has a significant impact on the cruising range, service life, charge and discharge control of an electric vehicle that uses multiple batteries as the power battery. Highly consistent performance is an essential process for lithium battery production. In order to verify the performance of the lithium battery automatic pack system, this paper used Flexsim software to establish a system simulation model, used the Dashboard data statistical method to analyze the running data of the simulation model, completed the system construction and testing, and used SPSS statistical analysis software to analyze the system test results. Using the paired sample T test, we verify that the system matching test results are accurate, that the cylindrical lithium battery matching automation equipment system has complete functions, is simple to interact with the computer, and meets the system design requirements.

Research on Testing and Calculation Analysis of Cargo Bay Fire-Extinguishing Agent Concentration Based on Different Loading in Civil Aircraft

In the history of international aviation, there have been many fire accidents of the cargo compartment. To ensure that the fire is extinguished in time when the cargo compartment is on fire, and to ensure the safety of aircraft and personnel, the design of the cargo compartment fire extinguishing system needs to be verified according to CCAR 25. According to the AC851-1 guidance, the verification of the cargo compartment's fire extinguishing system design aims to test and calculate the concentration of fire extinguishing agents used for the C-class cargo compartment based on different loading conditions of civil aircraft. Through the flight test of the cargo compartment under a no-load condition, it can be seen that the concentration of fire extinguishing agents in the cargo compartment is higher than 5% in the initial phase, higher than 3% in the 39,000ft and 10,000ft level flight phase, and the entire flight test phase is maintained above the suppression concentration required by the test, which meets the system design requirements. The concentration of fire extinguishing agents in the cargo compartment under a no-load condition is calculated and analyzed according to the maximum load rate (full load), and the result is higher than the required 3% suppression concentration.

Seismic performance evaluation of Y-shaped eccentric brace–high-strength steel frame structure based on remote collaborative hybrid test

A remote collaborative hybrid test (RCHT) system based on the OpenFresco platform was established. The seismic performance of the Y-shaped eccentric brace–high-strength steel frame (YEB–HSSF) structure was evaluated via the RCHT loading of a multistory and multi span YEB–HSSF model with two test substructures at different locations. The test phenomena and results showed that the maximum inter-story drift angles of the RCHT model were 0.0018 and 0.0077 rad under frequent-intensity and rare-intensity earthquakes, respectively, which satisfies the requirements of GB 50011-2010. Under the action of a rare intensity earthquake, the webs of the test substructure links preferentially entered the yield state with shear deformation, whereas the other members remained in the elastic state; this conforms with the design concept of damage-controllable structures. Finally, a finite-element pure numerical model corresponding to the RCHT model was established to further evaluate the seismic performance of YEB-HSSF structure. The results showed that the base shear distribution ratio resisted by the HSSF part in the global model tended to increase with increasing peak ground acceleration. Under the action of a rare 9 intensity earthquake, the shear links were close to the ultimate bearing capacity, and the shear distribution ratio resisted by the HSSF part exceeded 40%. This indicates that the YEB-HSSF structure satisfies the design requirements for dual systems based on GB 50011-2010.

Urban rail transit FAO system: technological development and trends

This paper introduces the worldwide history of fully automatic operation (FAO) system in urban rail transit, followed by the development status in China. Then, the architecture and characteristics of the FAO system are described, and the analysis method of system design requirements is proposed based on the human factors engineering. The key technologies are introduced from the aspects of signaling system, vehicle system, communication system, traffic integrated automation system and reliability, availability, maintainability, and safety (RAMS) assurance. Furthermore, based on the independent practical experience of the FAO system, this paper summarizes the management methods for the construction and operation of FAO lines and prospects its future development trends toward a more intelligent urban rail transit system.

Cogging Torque Reduction of Integer Gear Ratio Axial-Flux Magnetic Gear for Wind-Power Generation Application by Using Two New Types of Pole Pieces

Flux-modulated-type magnetic gears are expected to be applied as a step-up gear for wind-power generation because of their advantages, including high torque density and maintenance-free operation. Furthermore, the flux-modulated-type magnetic gears with an axial-flux structure have attracted great attention recently since they have a smaller axial length and are relatively easy to assemble. In some cases, magnetic gears are required to have an integer gear ratio based on the design requirements of the entire system, which results in larger cogging torque in the high-speed (H-speed) rotor that causes vibration, acoustic noise, and startup error. A skewed rotor structure is well known to be capable of reducing the cogging torque; however, it is complicated and poor in assembling, especially in a large-scale axial-flux magnetic gear (AFMG) used for the wind-power generation. To resolve the above problem, this article presents two new types of pole pieces for reducing the cogging torque: one is an unequal-space type, and the other is an unequal-width type. The validity of the two newly proposed types of pole pieces is proved by both a 3-D finite-element method (3D-FEM) and experiment.

Two-tier control structure design methodology applied to heat exchanger networks

Because of its paramount importance in the successful industrial control strategy of a given heat exchanger network (HEN), the control structure designs for providing appropriate manipulated variable (MV) and controlled variable pairings have received considerable attention. However, quite frequently HENs with such control structures face the problem of hard constraints, typically holding the HENs at less controlled operating space. So both the MV pairings and the above control pairings should be considered to design a control structure. This paper investigates the systematic incorporation of the two pairings, and presents a methodology for designing such two-tier control structure. This is developed based on the sequential strategy, coupling an indirect-tier with direct-tier control structure design, wherein the intention is realized in the former stage and the latter is implemented for further optimization. The MV identification and pairing are achieved through variations in heat load of heat exchangers to design the indirect-tier control structure. Then the direct-tier control structure is followed the relative gain array pairing rules. With the proposed methodology, on the one hand, it generates an explicit connection between the MV pairings and the HEN configuration, and the quantitative interaction measure is improved to avoid the multiple solutions to break the relationship among all the control pairings into individuals; on the other hand, a two-tier control structure reveals control potentials and control system design requirements, this may avoid complex and economically unfavourable control and HEN structures. The application of proposed framework is illustrated with two cases involving the dynamic simulation analysis, the quantitative assessment and the random test.

Design and Optimisation of an Enterprise Digital Management System Based on IoT Monitoring.

Modern enterprise management is developing rapidly, and one of the most important components of enterprise management is enterprise digital management. In this paper, the research background of enterprise digital management system is firstly elaborated, current situation of enterprise digital management work in enterprises is elaborated, then the current situation of the system research and development at home and abroad is also analysed and outlined in detail, and finally, according to the actual enterprise digital management situation of enterprises, combined with the system method of software development and corresponding technology, the new system design requirements of enterprises based on Internet of Things are proposed. Simulations show that the overall design and module design of the system in this paper are well managed, a system interface diagram can be given, and the database table structure and entity class diagram are applied to elaborate the database design.

TEMPERATURE CAPTURE AND IMAGE PROCESSING SYSTEM: A CASE STUDY

This paper describes a technical solution to stop the spread of COVID-19 by creating a system consisting of a video camera with a thermal sensor connected to a web-based platform, which would help to manage to restrict access of people who have fever into a building. The main purpose of the project system is to measure body temperature, to detect and to recognize the person that has at the moment or had fever in the past 14 days, the registration in the database of both the fever and the person, and validate the access of the person in the building if it has a temperature below 37 degrees Celsius. The technical details as analysis and determination of the domain of interest, development of the new system design, functional and non-functional requirements, interface, project planning, technical specification and quality of the proposed solution are discussed. The proposed system aims to reduce the number of employees responsible for collecting the temperature, thus no longer exposing them to the risk of infection.

Proximal policy optimization-based committee selection algorithm in blockchain-enabled mobile edge computing systems

To cope with the low latency requirements and security issues of the emerging applications such as Internet of Vehicles (IoV) and Industrial Internet of Things (IIoT), the blockchain-enabled Mobile Edge Computing (MEC) system has received extensive attention. However, blockchain is a computing and communication intensive technology due to the complex consensus mechanisms. To facilitate the implementation of blockchain in the MEC system, this paper adopts the committee-based Practical Byzantine Fault Tolerance (PBFT) consensus algorithm and focuses on the committee selection problem. Vehicles and IIoT devices generate the transactions which are records of the application tasks. Base Stations (BSs) with MEC servers, which serve the transactions according to the wireless channel quality and the available computing resources, are blockchain nodes and candidates for committee members. The income of transaction service fees, the penalty of service delay, the decentralization of the blockchain and the communication complexity of the consensus process constitute the performance index. The committee selection problem is modeled as a Markov decision process, and the Proximal Policy Optimization (PPO) algorithm is adopted in the solution. Simulation results show that the proposed PPO-based committee selection algorithm can adapt to the system design requirements with different emphases and outperforms other comparison methods.

Dynamic Logo Design System of Network Media Art Based on Convolutional Neural Network

Nowadays, we are in an era of rapid development of Internet technology and unlimited expansion of information dissemination. While the application of new media and digital multimedia has become more popular, it has also brought Earth shaking changes to our life. In order to solve the problem that the traditional static visual image has been difficult to meet people’s needs, a network media art dynamic logo design system based on convolutional neural network is proposed. Firstly, the software and hardware platform related to accelerator development is introduced, the advanced integrated design and calculation IP core are determined as the FPGA hardware accelerator, and the design objectives and requirements of the accelerator system are analyzed. The overall architecture of the accelerator system is designed. 76% of designers believe that the dynamic logo has promoted the corporate image. Then, the function and architecture of IP core are designed based on advanced synthesis, the code structure is standardized, the function is divided, and the operation acceleration is further optimized by using the instruction set of HLS. Finally, the design is integrated by Vivado HLS and Vivado IDE software. The experiment shows that the accelerator system has low power consumption and high resource utilization.

Design and Verification of Calorimeter for CFETR Neutral Beam Injection System Prototype with Negative Ion Source

Currently, a neutral beam injection (NBI) system prototype with a 200-keV negative ion source, called the negative neutral beam injection (NNBI) system, is under construction for the China Fusion Engineering Test Reactor Project. In the NNBI system, the calorimeter is an extremely important high-heat-flux component, and its panels have to withstand a heat flux density of up to dozens of MW/m2 under some extreme conditions; thus, its efficient heat transfer enhancement design and the corresponding supporting structural design are most important, especially under the condition of a 3600-s long pulse. According to the detailed design requirements of the NNBI system, an overall design scheme of the calorimeter based on the heat transfer enhancement structure of the swirl tube (SW for short) is proposed in this paper. By using the gas-liquid two-phase flow boiling model and the supporting structure’s finite element model, the heat transfer performance of the heat exchange module, the mass flow distribution and pressure drop of the entire cooling circuit of the component, and the strength of the support structure are evaluated to verify the feasibility of the design scheme. Finally, based on the proposed design scheme, the detailed design of the temperature monitor system, which has high reliability and economy, is completed. This research provides important theoretical and engineering support for the structural development of the calorimeter for the NNBI verification prototype and will also provide references for the design and development of other internal components of large-scale fusion devices.

Challenges and Opportunities of Patient Safety Event Reporting.

The World Health Organization (WHO) announced the first-ever World Patient Safety Day on September 17, 2019, which remarks a global campaign to create an awareness of patient safety and urges people to show their commitment to making healthcare safer. Reporting medical incidents or patient safety events (PSE) has been recommended as an effective approach for the detection of patterns, discovery of underlying factors, and generation of solutions. It is believed that PSE reporting systems (e-reporting) could be a good resource to share and to learn from the reporting if the event data are collected in a properly structured format. Unfortunately, the prevalence of underreporting and low quality of the reports have become barriers to ultimately achieve the goal of preventing and reducing medical incidents. This chapter describes the efforts that have been made to improve e-reporting through informatics approaches, including a review of PSE taxonomies and conceptual frameworks, studies of medication events, patient falls, and PSE involved in health information technologies, as well as discussions of design requirements for future e-reporting systems.

Design and experimental testing of safe flight control system for novel vertical take-off and landing aircraft

This paper describes the design and flight test of the control system of a novel octocopter with new topology to improve aerodynamic performance and efficiency. The article analyzes the advantages of the new configuration and analyzes the feasibility of the control method which can ensure fault-tolerant control when one rotor of the aircraft stops in theory. The feasibility verification is carried out through a prototype flight test. The power and hardware platform of the octocopter UAV was set up according to the requirements of structural and control system design. Flight tests were carried out multiple times, and the UAV’s redundant actuation was able to successfully stabilize the vehicle, even after a single rotor stopped functioning. Under normal flight conditions, smooth flight and effective control could be ensured for the UAV, while under the condition of a single rotor having stopped functioning, the control method was able to effectively utilize the other seven rotors to provide a proper lift force and to control the aircraft to perform basic motions such as pitch, roll, and yaw.

Sensifi: A Wireless Sensing System for Ultrahigh-Rate Applications

Wireless sensor networks (WSNs) are being used in various applications, such as structural health monitoring and industrial control. Since energy efficiency is one of the major design factors, the existing WSNs primarily rely on low-power, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">low-rate</i> wireless technologies, such as 802.15.4 and Bluetooth. In this article, by proposing Sensifi, we strive to tackle the challenges of developing <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ultrahigh-rate</i> WSNs based on the 802.11 (WiFi) standard. As an illustrative structural health monitoring application, we consider the spacecraft vibration test and identify system design requirements and challenges. Our main contributions are as follows. First, we propose packet encoding methods to reduce the overhead of assigning accurate timestamps to samples. Second, we propose energy-efficiency methods to enhance the system’s lifetime. Third, to enhance sampling rate and mitigate sampling rate instability, we reduce the overhead of processing outgoing packets through the network stack. Fourth, we study and reduce the delay of processing time synchronization packets through the network stack. Fifth, we propose a low-power node design, particularly targeting vibration monitoring. Sixth, we use our node design to empirically evaluate energy efficiency, sampling rate, and data rate. We leave large-scale evaluations as future work.

Systematic Mapping of Digital Gap and Gender, Age, Ethnicity, or Disability

Rapid technological evolution defines the first two decades of the millennium. This phenomenon has increased the digital gap, disparities, and inequalities in global and local contexts. This paper reports a systematic literature mapping of 180 articles published from 2000 to 2021 discussing the digital gap. The documents were retrieved using boolean operations in two databases, adding terms related to gender, age, ethnicity, and disabilities, focusing on population groups that are especially vulnerable to the effects of this phenomenon. The method included categorizing the retrieved documents to provide a general view of the most concerning topics in the academic and research community. This analysis concludes (a) the approaches to address this topic are diverse, as this is a multilayered, complex, and interconnected issue; (b) many studies refer to developed countries; however, fewer are those who observe or analyze the underdeveloped regions; (c) the majority of published papers in the last decade report information and communication technologies (ICT) and their role in bridging the gap, showing an opportunity area for designing these technologies considering more accessible approaches through flexible technology approaches; (d) this study’s results are a valuable source of information to identify the design requirements for accessible products and service systems. The last section provides a detailed explanation of the findings.

Implementation of Snow and Ice Sports Health and Sports Information Collection System Based on Internet of Things.

The promotion of ice and snow sports not only provides professional athletes for the Winter Olympics but also acts as appreciative mass bases for ice and snow sports. The appearance of ice and snow sports will bring a new consumption pattern and develop a new ice and snow industry. In this paper, an Internet of Things (IoT)-based sports information collection system which is specifically designed and developed for the healthcare domain specifically in the snow and ice sports is proposed. The physiological parameters such as body temperature, ECG, blood pressure, blood sugar, and blood oxygen saturation are captured through various monitoring devices. These physiological parameters are transmitted to the mobile device by the wireless module and mobile device that receives and displays these physiological parameters. A complete hardware design of the whole ice and snow sports health and sports information acquisition system, which is based on the Internet of Things, is given, and then, there is the overall design scheme of the system, such as adopted modular design for the system, attitude measurement unit, UWB positioning unit, data storage, and communication unit, respectively. The measurement results of the professional medical equipment are compared with those of acquisition equipment in real environment of ice and sports. These results have verified accuracy of data collected by acquisition equipment and meet the design requirements of the proposed system.