摘要 ：

Providing an additional hole extraction path can significantly enhance the resistance to single-event radiation of SOI-LIGBT devices. This paper designs a 550 V Double RESURF SOI-LIGBT device and studies its single-event effects through simulation. The results indicate that the designed NCSP-LIGBT structure significantly improves resistance to single-event radiation without excessively sacrificing conduction performance. © Published under licence by IOP Publishing Ltd.

关键词 ：

Radiation effects Insulated gate bipolar transistors (IGBT) Incident solar radiation

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With the vigorous development of transportation infrastructure in various countries, the traffic network within the city is becoming more and more complex, and when an emergency occurs in one or more areas of the city, it will inevitably cause traffic congestion in the area and keep spreading. There are still many challenges to solve the urban emergency route planning problem. In this paper, we have employed a double layer search structure, where we have empowered the traditional A* model with a neural network, to construct a region-level dynamic path planning model known as "Double Layer A*". The model divides the road network into two layers, and implements the outer layer and inner layer search. In the outer layer search, we use the historical cab travel data for training to achieve the general direction planning; in the inner layer search, we update the original planning according to the changes of the road condition characteristics of the regional nodes, and perform the re-planning in real time. We conducted experimental evaluations using the road network data of Beijing, and the results showed that compared to a single-layer search structure path planning model, our Double layer A* model planned paths with higher similarity in land characteristics, connectivity, and average connectivity between adjacent nodes, which demonstrates the effectiveness and reasonableness of the Double layer A* model in emergency path planning.

关键词 ：

Search problems neural network Urban areas Routing real-time path planning Roads Map grid Path planning Navigation A* algorithm Planning

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Determining the migration rules of oxygen species in catalytic combustion, especially for catalysts composed of transition metal oxides, is essential yet challenging. This study hydrothermally synthesized nanospherestructured cerium dioxide (CeO 2 ) and its copper -loaded catalysts (Cu/CeO 2 ) to identify the distinct functions of superficial oxygen species (O) and lattice oxygen (O 2- ). The presence of Cu-Ce solid solution at the Cu/CeO 2 interface lowered the apparent activation energy for the catalytic combustion of propane and soot. The catalytic combustion of propane followed the Mars -van Krevelen mechanism, with O 2- serving as the dominant reactive phase while O played a subordinate role. The solid-solid reaction between soot and superficial oxygen of the catalyst was responsible for catalyzed soot combustion. The O species produced by surface defective sites exhibited higher activity than O 2- , which drained easily at the beginning of the reactions. The isotopic oxygen exchange tests revealed the mechanism of metal oxide (CuO/CeO 2 ) interactions for active oxygen species migration, with the results demonstrating the solid solution at the phase interface as portholes for oxygen migration, thus increasing oxygen mobility between the gaseous phase and the surface by lowering the migration activation energy. In situ, infrared results showed that the reaction path of soot catalytic combustion was single, without any intermediate production formation, compared to multiple paths in the propane oxidation process. This study provided an easily implemented and widely applicable method, which deepens our understanding of the characterization of the function and migration of predominant oxygen species in diverse combustion reactions involving oxide -based catalysts. Additionally, this study clarified differences and similarities between the reaction mechanisms of solid-solid and solid-gas catalysis.

关键词 ：

Propane Oxygen exchange Soot Active oxygen species

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Micro-welding of Al and Cu foils is increasing used in various industries, particularly in the production of battery components for electric vehicles. However, direct fusion welding of Al and Cu may compromise joint mechanical properties due to the formation of brittle intermetallic compounds (IMC). Consequently, strategies for controlling IMC to enhance joint mechanical properties have received significant research attention. In this study, lap welds of 1050 Al foil and T2 Cu foil (both 200 mu m thick) are achieved using a single-mode fiber laser equipped with a scanning galvanometer. This setup enables spatial power modulation for laser spot welding via beam spiral scanning. Notably, laser fusion welding occurs along the laser beam scanning path, while laser weld-brazing is achieved through heat conduction in the spiral spacing between the adjacent scanning paths, resulting in a hybrid joint with alternated fused and brazed areas. The laser weld-brazing areas expand the effective connection area of the joint, improving its load-bearing capacity while effectively controlling IMC compared to fusion joints. The screw-type hybrid joints exhibit excellent mechanical properties, with a maximum tensile strength of 140 MPa. Experimental and simulation results indicate the mechanism for hybrid joint formation and improvement in mechanical properties. This study provides an effective strategy for regulating joint microstructure to mitigate the negative influence of IMC.

关键词 ：

Mechanical properties Laser weld-brazing Al/Cu dissimilar joint Microstructure Laser welding

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The existing constitutive models of shape memory alloy (SMA) cannot accurately describe the mechanical behavior in martensitic strengthening segment since their loading and unloading paths in strengthening segment completely overlap. This study proposes a multi-segment linear mathematical model for SMA, which realizes the separation of loading path and unloading path in strengthening segment. A four-story steel frame structure and corresponding braced structures with various SMA constitutive models are designed, and seismic control effects of SMA braces with these models are analyzed and compared through time history analysis. The results show that the sub-cycle unloading mode of SMA constitutive model affects the seismic mitigation capacity of SMA brace in a certain extent. The position of the inflection point of unloading path has very little influence on the structural control ability of SMA braces. The SMA brace using the SMA constitutive model with a single linear sub-cyclic unloading path has the minimal seismic response and the highest seismic reduction ratio. For most evaluation indexes, the seismic mitigation ability calculated by the proposed path separation constitutive model is in the middle of the results calculated by the existing models. SMA models without considering the mechanical behavior of strengthening segment may lead to an erroneous estimation of the energy consumption of SMA brace and the structural damage. The difference of simulation results among various SMA constitutive models is almost independent with ground motion.

关键词 ：

steel frame structure shape memory alloy seismic control constitutive model comparison analysis

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Border Gateway Protocol (BGP) is a standard inter-domain routing protocol for the Internet that conveys network layer reachability information and establishes routes to different destinations. The BGP protocol exhibits security design defects, such as an unconditional trust mechanism and the default acceptance of BGP route announcements from peers by BGP neighboring nodes, easily triggering prefix hijacking, path forgery, route leakage, and other BGP security threats. Meanwhile, the traditional BGP security mechanism, relying on a public key infrastructure, faces issues like a single point of failure and a single point of trust. The decentralization, anti-tampering, and traceability advantages of blockchain offer new solution ideas for constructing secure and trusted inter-domain routing mechanisms. In this paper, we summarize the characteristics of BGP protocol in detail, sort out the BGP security threats and their causes. Additionally, we analyze the shortcomings of the traditional BGP security mechanism and comprehensively evaluate existing blockchain-based solutions to address the above problems and validate the reliability and effectiveness of blockchain-based BGP security methods in mitigating BGP security threats. Finally, we discuss the challenges posed by BGP security problems and outline prospects for future research.

关键词 ：

prefix hijacking BGP security blockchain trust model secure routing

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With the development of communication and transmission technologies, the applications of Internet of Things (IoT) and telemedicine are increasingly sensitive to network latency. To meet this urgent demand, learning based routing approaches emerge, with better performance and higher flexibility. These routing approaches can be divided into single-path and multipath, which have lower transmission delay and better load balancing respectively. However, the traffic scheduling policy is not only affected by the network states but also needs to consider the requirements for traffic tasks. We propose a Task-Oriented Hybrid Routing Approach (TOHRA) based on Deep Deterministic Policy Gradient (DDPG) in Software-Defined Networking (SDN). First, the hybrid routing optimization algorithm comprehensively considers the network states and task requirements, and outputs a task-oriented hybrid routing that combines the advantages of single-path and multipath. Moreover, we design a hop-by-hop traffic segmentation model based on DDPG to output the traffic segmentation ratio on hybrid routing to adapt to the changing transmission path. Experimental results show that TOHRA achieves the best performance of load balancing and network throughput. Especially in the case of Type C tasks in Germany topology, the average network throughput of THORA is increased by 32.86%, and the average variance of link load rate is reduced by 46.62%.

关键词 ：

Routing optimization Hybrid routing Deep deterministic policy gradient Software-defined networking Traffic segmentation

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Due to its high hardness and excellent wear resistance, single crystal diamond has been widely applied in me-chanical processing. However, the outstanding hardness leads to great difficulties in the machining of diamond by traditional strategies. In this study, a synchronous feed laser method is developed to realize low damage, high efficiency, and high precision machining of single crystal diamond cutting tools. The disadvantages of traditional direct laser machining, including fullerene residue, bending behavior, and the plasma-shield effect, are well avoided by the good control of the scanning path during the laser fabrication, which enlarges the entrance of the kerf and reduces the air pressure inside the kerf. The synchronous feed laser machining can realize the remarkable increase of kerf depth at high speed, as well as a minimum roughness of-147 nm on the cutting surface. It provides a novel, high efficiency, and high precision strategy for the preparation of high quality single crystal diamond tools.

关键词 ：

Picosecond laser Diamond Cutting tool Synchronous feed machining

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With the progress of Internet of Things (IoT) services, especially the industrial IoT (IIoT) service, and personal consumption by wearable devices, the requirement from the perspective of capability, reliability and latency for consumer scenarios (e.g., AR/VR) and industry scenarios becomes more and more stringent. Due to limited uplink (UL) transmission power, especially for the new radio reduced capability (NR-RedCap) devices and wearable devices, UL transmission would be a bottleneck. In this paper, in order to increase the coverage and decrease the latency at the same time, a new transmission mechanism based on an adaptive user equipment (UE) aggregation, i.e., a multi-path transmission, is discussed, wherein multiple devices are aggregated to increase UL power and explore the diversity gain. According to the quality of radio link between UEs and base station (BS), data transmission can be a single path based on an indirect link or direct link, or over multiple paths from multiple transmission nodes. The procedure to support such UE aggregation based transmission is also designed. The performance gain is provided and discussed in detail to verify the benefit of the proposed mechanism. This paper helps to identify main difference under different cooperation schemes and provide an insight into UE aggregation based transmission. © 2023 IEEE.

关键词 ：

Power quality Radio links Radio transmission Mobile telecommunication systems Wearable technology Internet of things

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Dry reforming of methane (DRM) has been investigated for more than a century; the paramount stumbling block in its industrial application is the inevitable sintering of catalysts and excessive carbon emissions at high temperatures. However, the low-temperature DRM process still suffered from poor reactivity and severe catalyst deactivation from coking. Herein, we proposed a concept that highly durable DRM could be achieved at low temperatures via fabricating the active site integration with light irradiation. The active sites with Ni-O coordination (Ni-SA/CeO2) and Ni-Ni coordination (Ni-NP/CeO2) on CeO2, respectively, were successfully constructed to obtain two targeted reaction paths that produced the key intermediate (CH3O*) for anticoking during DRM. In particular, the operando diffuse reflectance infrared Fourier transform spectroscopy coupling with steady-state isotopic transient kinetic analysis (operando DRIFTS-SSITKA) was utilized and successfully tracked the anticoking paths during the DRM process. It was found that the path from CH3* to CH3O* over Ni-SA/CeO2 was the key path for anticoking. Furthermore, the targeted reaction path from CH3* to CH3O* was reinforced by light irradiation during the DRM process. Hence, the Ni-SA/CeO2 catalyst exhibits excellent stability with negligible carbon deposition for 230 h under thermo-photo catalytic DRM at a low temperature of 472 degrees C, while Ni-NP/CeO2 shows apparent coke deposition behavior after 0.5 h in solely thermal-driven DRM. The findings are vital as they provide critical insights into the simultaneous achievement of low-temperature and anticoking DRM process through distinguishing and directionally regulating the key intermediate species.

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