Multiple Terminals Research Articles

Reliability Evaluation of MMC‐MTDC System Considering Device Failure Rates and Multi‐State Transition

ABSTRACTThe modular multi‐level converter based multi‐terminal high voltage direct current (MMC‐MTDC) system, with its numerous power devices and diverse operating states, poses a significant challenge for reliability evaluation. The paper introduces a method for modeling and assessing the reliability of MMC‐MTDC, considering both power device failure rates and multi‐state transitions of multiple terminals. To determine the weights of influence, the analytic hierarchy process (AHP) is employed to evaluate the impact of sub‐modules (SMs), the controller system, and the water cooling systems of an MMC. Subsequently, a multi‐state transition model is established to describe the changes in the operation mode of the MMC‐MTDC. On this basis, the reliability evaluation via semi‐Markov processes is implemented. A case study is performed on the reliability of a ±200 kV five‐terminal system and the results are compared with practical operation data.

Loss of C1q alters the auditory brainstem response.

Neural circuits in the auditory brainstem compute interaural time and intensity differences used to determine the locations of sound sources. These circuits display features that are specialized for these functions. The projection from the ventral cochlear nucleus (VCN) to the medial nucleus of the trapezoid (MNTB) body travels along highly myelinated fibers and terminates in the calyx of Held. This monoinnervating synapse emerges during development as multiple inputs are eliminated. We previously demonstrated that elimination of microglia with a colony stimulating factor-1 inhibitor results in impaired synaptic pruning so that multiple calyceal terminals reside on principal cells of MNTB. This inhibitor also resulted in impaired auditory brainstem responses (ABRs), with elevated thresholds and increased peak latencies. Loss of the microglial fractalkine receptor, CX3CR1, decreased peak latencies in the ABR. The mechanisms underlying these effects are not known. One prominent microglial signaling pathway involved in synaptic pruning and plasticity during development and aging is the C1q-initiated compliment cascade. Here we investigated the classical complement pathway initiator, C1q, in auditory brainstem maturation. We found that C1q expression is detected in the MNTB by the first postnatal week. C1q levels increased with age and were detected within microglia and surrounding the soma of MNTB principal neurons. Loss of C1q did not affect microglia-dependent calyceal pruning. Excitatory and inhibitory synaptic markers in the MNTB and LSO were not altered with C1q deletion. ABRs showed that C1q KO mice had normal hearing thresholds but shortened peak latencies. Altogether this study uncovers the developmental time frame of C1q expression in the sound localization pathway and shows a subtle functional consequence of C1q knockdown.

A Novel Polynomial-Time Algorithm for Automatic Layout of Branching Cables in a Fixed Topology

Designing the layout for complex electromechanical products involves the challenging task of automatically laying out cables. This challenge is particularly pronounced in the case of branch cables, which are more intricate due to their multiple connection terminals and branches. This paper presents a polynomial-time wiring algorithm based on dynamic programming to determine branching point locations in the layout design of cables, given the electrical definition of the wire harness. The method considers various engineering constraints, including obstacle avoidance, wall adherence, minimum bend radius, and gray areas. To validate our method, we implemented a branch cable auto-layout system through secondary development based on the UG platform. The experimental results indicate the effectiveness of our approach, demonstrating promising performance in terms of time and high-quality layouts. This showcases its potential for practical application in cable layout design for complex electromechanical systems.

Nine-Switch Multiport Converter Applied to Battery-Powered Tramway with Reduced Leakage Current

Electrically powered rail transport is constantly increasing in order to meet the high demand for people and cargo transportation, whether with high-speed trains, subways, suburban trains, or electric tramways. In these types of applications, power electronics solutions such as integrated and efficient converters with multiple functionalities are highly desirable. Among these converters, one family stands out for its ability to generating multiple output terminals with reduced number of switches, namely, the nine-switch converter. Therefore, this paper proposes a multiport converter solution based on the nine-switch converter topology that integrates multiple functionalities with a reduced switch count. The converter, responsible for the power drive of the electric tramway, is exclusively powered by a battery. Moreover, it presents a strategically connected passive filter that provides a low-impedance path for high-frequency currents, avoiding leakage of the current circulation in the induction motor. Its phase-shift pulse-width modulation is capable of reducing the high-frequency components of the current delivered by the battery. The energy storage system is designed to optimize the system capacity based on the known real load profile of a public tramway, with a maximum power of 532.1 kW. The control system is designed and applied considering the battery as the energy source. Simulations were performed in the Matlab/Simulink environment to validate the proposed system, along with experiments using a reduced-scale prototype controlled by the dSPACE platform. The results present the converter’s proper operation with integration of the source and AC load, presenting improved features compared with conventional solutions in terms of reduced leakage of the current circulation from the AC load and reduced battery current ripple.

Self-Powered Dual-Mode Pressure Sensor Based on Porous Triboelectric Nanogenerator for Use in Smart Home System

With the rapid evolution of the Internet of Things (IoT), smart home systems have greatly improved people’s lifestyles and quality of life. However, smart home systems based on a single sensor cannot efficiently control multiple terminals, which limits product penetration into lower-end markets. Here, we have developed a dual-mode smart home system based on a porous triboelectric nanogenerator (TENG), which effectively compensates for the shortcomings of smart home systems being unable to control multiple appliances through a single switch. Benefitting from the remarkable electronegativity of MXene and the ameliorative specific surface area of the friction layer, the output characteristics of the porous TENG are greatly improved. Under the identical external stimulus, the open-circuit voltage (VOC) and short-circuit current (ISC) of the porous TENG were 3.03 and 3.04 times higher than those of the TENG with a pure PVDF membrane used as the friction layer. Thanks to the excellent output performance and good linear relationship between pressure and voltage, the developed dual-mode smart home system could efficiently control multiple terminals through a single sensor. This work not only provides theoretical support for developing high-performance TENGs but also paves the way to designing multifunctional smart home systems.

Dynamic Tugboat Scheduling for Large Seaports with Multiple Terminals

Effective utilization of tugboats is the key to safe and efficient transport and service in ports. With the growth of maritime traffic, more and more large seaports show a trend toward becoming super-scale, and are divided into multiple specialized terminals. This paper focuses on the problem of large-scale tugboat scheduling. An optimization problem is formulated considering the cross-region constraints and uncertainties during tugboat operation. An improved genetic algorithm is proposed based on the reversal operation (GA-RE) to solve the formulated Tug-SP. A task-triggered strategy is designed for dynamic scheduling and dealing with uncertainties. Taking Zhoushan Port as a representation of multi-terminal seaports, simulation experiments are carried out to demonstrate the effectiveness of the proposed method. Compared with historical scheduling data and the standard GA, the proposed method shows good performance in solving different scale instances (including a large-scale instance of 191 ships) in terms of solution quality and computational time.

Precise and Robust IMU-Centric Vehicle Navigation via Tightly Integrating Multiple Homogeneous GNSS Terminals

Precise and Robust IMU-Centric Vehicle Navigation via Tightly Integrating Multiple Homogeneous GNSS Terminals

A Basic Study on the Existence of the Pairs of Edge-Disjoint Steiner Tree Connecting Multiple Terminals on Graphs

A Basic Study on the Existence of the Pairs of Edge-Disjoint Steiner Tree Connecting Multiple Terminals on Graphs

Container Scheduling considering Customer Satisfaction in the Context of Internal Circulation

As China’s foreign trade continues to progress, a trade surplus in inland container transportation has emerged. At the same time, businesses need to not only focus on transportation tasks but also prioritize customer service requirements. To address the issues of container supply shortages and inefficient empty container allocation, this article establishes a container truck scheduling model that includes multiple terminals and yards. With the objective of minimizing total costs and maximizing customer satisfaction during the allocation process, the model incorporates coupling constraints between vehicle flow and container flow. Instance verification using Cplex demonstrates that the proportions of different cost types and the range of expected time windows can impact the formulation of transportation plans and, consequently, total costs. Lastly, numerical experiments are conducted to analyze the cost variations and transportation plan preferences under different ranges of time windows and different weights assigned to transportation costs and fixed costs.

A Parallel Multimodal Integration Framework and Application for Cake Shopping

Multimodal interaction systems can provide users with natural and compelling interactive experiences. Despite the availability of various sensing devices, only some commercial multimodal applications are available. One reason may be the need for a more efficient framework for fusing heterogeneous data and addressing resource pressure. This paper presents a parallel multimodal integration framework that ensures that the errors and external damages of integrated devices remain uncorrelated. The proposed relative weighted fusion method and modality delay strategy process the heterogeneous data at the decision level. The parallel modality operation flow allows each device to operate across multiple terminals, reducing resource demands on a single computer. The universal fusion methods and independent devices further remove constraints on the integrated modality number, providing the framework with extensibility. Based on the framework, we develop a multimodal virtual shopping system, integrating five input modalities and three output modalities. The objective experiments show that the system can accurately fuse heterogeneous data and understand interaction intent. User studies indicate the immersive and entertaining of multimodal shopping. Our framework proposes a development paradigm for multimodal systems, fostering multimodal applications across various domains.

RIS-Assisted Covert Transmission in Satellite–Terrestrial Communication Systems

With the development of the sixth-generation wireless communication technology, the difficulty of covert communication in the satellite communications system (SCS) is further increased. In this paper, a satellite covert communication system based on reconfigurable intelligent surface (RIS) is studied, which consists of a satellite, a terrestrial receiver, RIS, and a warden. Specifically, the ground terminal simultaneously receives the signal transmitted by the satellite and the signal reflected by RIS, while the warden wants to overhear the transmitted signal from the satellite and that reflected by the RIS. The main target of this wort is to maximize the minimum covert rate to improve signal quality while considering the limited onboard resources, the hardware constraints of RIS, and the requirement to implement covert communication. To address the non-convex problem, we propose an effective alternating optimization scheme by jointly optimizing transmitter precoding and RIS to improve the covert communication performance of the considered system. In addition to ideal RIS, we also consider the non-ideal RIS, the angle of which is discrete in the actual case. In addition, several simplified methods are proposed to decrease the computational complexity of the covert communication optimal problem under multiple terminals. Finally, simulation results are provided to verify the superiority of the proposed scheme compared with the benchmark scheme, which suggests that the considered RIS-based satellite-terrestrial covert communication system can significantly improve the achievable masking.

Recent advancements in implantable neural links based on organic synaptic transistors

AbstractThe progress of brain synaptic devices has witnessed an era of rapid and explosive growth. Because of their integrated storage, excellent plasticity and parallel computing, and system information processing abilities, various field effect transistors have been used to replicate the synapses of a human brain. Organic semiconductors are characterized by simplicity of processing, mechanical flexibility, low cost, biocompatibility, and flexibility, making them the most promising materials for implanted brain synaptic bioelectronics. Despite being used in numerous intelligent integrated circuits and implantable neural linkages with multiple terminals, organic synaptic transistors still face many obstacles that must be overcome to advance their development. A comprehensive review would be an excellent tool in this respect. Therefore, the latest advancements in implantable neural links based on organic synaptic transistors are outlined. First, the distinction between conventional and synaptic transistors are highlighted. Next, the existing implanted organic synaptic transistors and their applicability to the brain as a neural link are summarized. Finally, the potential research directions are discussed.

Solving the Inter-Terminal Truck Routing Problem for Delay Minimization Using Simulated Annealing with Normalized Exploration Rate

The growth in containerized shipping has led to the expansion of seaports, resulting in the emergence of multiple terminals. While multi-terminal systems increase port capacity, they also pose significant challenges to container transportation, particularly in inter-terminal movements. Consequently, the transportation delay of containers in inter-terminal operations demands crucial attention, as it can adversely affect the efficiency and service levels of seaports. To minimize the total transportation delays of the inter-terminal truck routing problem (ITTRP), we introduce simulated annealing with normalized acceptance rate (SANE). SANE improves the exploration capability of simulated annealing (SA) by dynamic rescaling of the transportation delay objective to modify the acceptance probability. To validate the quality of solutions provided by SANE, we have developed a mathematical model that provides a set of linear formulations for ITTRP constraints, avoiding the known set-partitioning alternative. Experimental results showed that for small-scale ITTRP instances, SANE achieved a solution close to the optimal. In larger instances with 100–120 orders, SANE found feasible suboptimal solutions within 15–21 seconds, which is unattainable using the exact solver. Further comparison with baselines indicates that SANE provides considerable improvements compared to both SA and Tabu search in terms of the objective value.

Pipeline Leak Detection System

This article deals with a development of a pipeline leak detection system for monitoring hydrocarbon pipelines in real time. This system is based on the integration of methods of negative pressure waves of propagation and mass and momentum balance calculation. The system is designed to receive real-time data from multiple remote terminals which operate in the field and its processing in a monitoring center. For validation of the system, a liquefied gas pipeline of 20” diameter and 60 km in length was used. The validation of the system was done by comparing the events detected and located by the developed system and the results of verification of real leak locations. Some inspection results using this system are presented.

Dynamic deployment method based on double deep Q-network in UAV-assisted MEC systems

The unmanned aerial vehicle (UAV) assisted mobile edge computing (MEC) system leverages the high maneuverability of UAVs to provide efficient computing services to terminals. A dynamic deployment algorithm based on double deep Q-networks (DDQN) is suggested to address issues with energy limitation and obstacle avoidance when providing edge services to terminals by UAV. First, the energy consumption of the UAV and the fairness of the terminal’s geographic location are jointly optimized in the case of multiple obstacles and multiple terminals on the ground. And the UAV can avoid obstacles. Furthermore, a double deep Q-network was introduced to address the slow convergence and risk of falling into local optima during the optimization problem training process. Also included in the learning process was a pseudo count exploration strategy. Finally, the improved DDQN algorithm achieves faster convergence and a higher average system reward, according to experimental results. Regarding the fairness of geographic locations of terminals, the improved DDQN algorithm outperforms Q-learning, DQN, and DDQN algorithms by 50%, 20%, and 15.38%, respectively, and the stability of the improved algorithm is also validated.

Joint Terminal Pairing and Multi-Dimensional Resource Allocation for Cooperative Computation in a WP-MEC System

The combination of multi-access edge computing (MEC) and wireless power transfer (WPT) can potentially improve system performance and prolong terminals’ battery lifetime. In this paper, we study cooperative computation in a wireless powered multi-access edge computing (WP-MEC) system. In this system, there are an access point (AP) deployed with an MEC server and multiple cellular terminals that are powered by harvested energy from a power station. The computational task of each terminal is partially completed locally and partially offloaded to the AP and an nearby idle terminal. In order to minimize energy consumption in the system, we jointly optimize terminal pairing and multi-dimensional resource (i.e., computing power and communication resource) allocation. A non-convex mixed-integer non-linear programming (MINLP) problem is formulated in this paper. To solve this challenging problem, we propose a bilevel optimization approach, in which the multi-dimensional resource allocation scheme is designed under given terminal pairing relationships in the inner level, and then the pairing relationships between terminals are obtained in the outer level based on the obtained multi-dimensional resource allocation scheme. Extensive numerical results show that the proposed bilevel optimization scheme can reduce energy consumption considerably compared to some baseline schemes.

Defect engineering of two-dimensional ultrathin Co3O4 nanosheets for wireless and high-performance monitoring of the sensing properties of volatile organic compounds

Volatile organic compounds (VOCs) as serious outdoor and indoor air pollutants have attracted great attention. Many detection technologies of VOCs have been investigated. However, it is challenging to develop an efficient and portable wireless sensor for monitoring VOCs. Here, we proposed a new strategy to obtain a high-performance VOC sensor based on two-dimensional Co3O4 nanosheets (NSs) with numerous oxygen vacancy defects. The Co3O4 NS-30 W sensor detected 200 ppm ethanol and exhibited a high response value (10.70) and fast response and recovery behavior (20 s and 17 s, respectively). The effect of oxygen vacancy defects on the sensitive properties was studied by theoretical calculations on the (110) plane of Co3O4. Furthermore, a unique VOC wireless sensor was fabricated in order to enable wireless early warning from multiple terminals and monitoring of alcohol in exhaled gas. The VOC sensor exhibited a promising potential for precisely monitoring the alcohol consumption of drivers.

Industrial Automation Debug Message Display Over Modbus RTU Using C#

Purpose: To debug any device needs to display debug message. Seeing the message, we can detect what is the issue in our program. The are several popular debug tools available. The popular is JTAG. This debug interface is not available to debug inside all embedded systems. Instead of it, the Researcher uses a serial debug terminal. However, it has several drawbacks. Its wire length is generally within the table. The message is displayed only in one terminal. Sometimes the connected system is damaged due to high voltage spike injection. Here we demonstrate a procedure to eliminate all the above drawbacks. Instead of a direct serial display, we recommend using a modified serial debugger like Modbus hooked debug display. It is safe, can display multiple arrays simultaneously using broadcast messages, and can transmit long-range data. We developed a terminal program in C#. We provide a sample Embedded side test program. The complete project code is available to download. Design/Methodology/Approach: First, we create a Graphical user interface using C# language. To display the message, we use the “Listbox” control. We added a timer control to fetch the data availability. The timer interval is one millisecond by default. Within this time, it checks whether any data is reached. When the message/data arrives, it starts parsing. At first, it reads the Device ID. If the device ID matches, then it checks the CRC. If CRC is valid, it extracts the data from the received packets and displays it inside the list box. Findings/Result: Various tools are needed to resolve the issue when we debug the system. We connect the debugger and try to uncover the problem. Sometimes we do less concentrate on the hardware connection. So, there are chances of a wrong connection. Further, it can lead to the cause for damage to our PC/laptop. Here is our approach to minimize the damage which is unintentionally created. We isolate the PC/Laptop from the debugging system. It is safe and reliable. The researchers, new to embedded system debugging, can get information on where they can safely debug by creating an isolated environment. Originality/Value: This work provides some efficient view to debug message display using Modbus. It has several advantages over a simple serial debug interface. It can be long-range. The same message can be displayed in multiple terminals for team debugs season. The Researcher working with various team members on the same project can be viewed effectively. The new Researcher can be found some good reference information from this work. Paper Type: Experimental-based Research.

Operation characteristics based on a novel performance model based on capacity utilization rate of a variable refrigerant flow air conditioning system

In the context of a large market share, enhancing the actual performance of variable refrigerant flow (VRF) air-conditioning systems is of considerable importance. The operating states of indoor units (IUs) significantly influence the energy efficiency of a VRF system with multiple indoor terminals. Therefore, it is challenging to address accurate and concise representation of the operational characteristics of IUs for analyzing their impact on system performance. This study explored a novel performance index called capacity utilization rate (CUR) to illustrate the effect of IUs on system performance and developed a performance model based on this index. Simulation and experimental results demonstrated that energy efficiency and evaporating temperature decrease with a reduction in CUR under specific ambient temperatures and part-load rates. The proposed performance model was applied to real buildings in field tests to examine the operational characteristics of the VRF system. This research offers valuable insights for system design, performance simulation, and performance evaluation of VRF systems.

Experimental investigation of an air source heat pump with multigroup heat pipe radiators

As a clean and sustainable electrified heating technology, air source heat pump (ASHP) has been widely used in household in China. However, some problems occurred with the commonly used water loop system, such as low efficiency, complicated structure, more likely to be frozen and burst as well as high electric energy consumption, etc. In this paper, a new air source heat pump with multigroup heat pipe radiators (ASHPMP) was presented. In ASHPMP system, the condenser and heat pipe were coupled together to form a new type of heat radiation terminal, which was named as heat pipe radiators, multiple terminals driven by the compressor provided heat for several rooms. An experimental apparatus of the ASHPMP system was developed and the experiment was carried out in residential buildings also, and R410A was used in the heat pump and R134a was used in heat pipes. The influence of temperature, pressure of heat pump and heat pipe on the heating performance of ASHPMP under frosting/defrosting condition was analysed. The results showed that the new system can operate stably under outdoor temperatures of −12.7 °C to 6.5 °C. As the indoor temperature was set at 20 °C, the heating coefficient of performance (heating COP) could reach up to 3.15 with outdoor temperature −12.7 °C, and it was 6.73 with outdoor temperature 6.5 °C.