The effect caused by asymmetric structures on the performance of the AlGaN/GaN bilateral impact-ionizat-ionavalanche-transit-time (BIMPATT) device is studied in this article. The asymmetric structures include the asymmetry of the bilateral channel lengths by changing the anode position and the asymmetry of the two-dimensional electron gas (2DEG) concentrations by changing the AlGaN thickness. The asymmetry affects the direct current (DC), radio frequency (RF), and noise characteristics of the BIMPATT. Large-signal analysis shows that the asymmetric structures improve the operating frequency but reduce the maximum power and efficiency of the BIMPATT. The asymmetric structures show better RF characteristics than the symmetric structure in the high-frequency band. At last, the asymmetric structures increase the noise performance of the BIMPATT. The reason for these phenomena is the asymmetry of avalanche ionization region and intensity caused by the asymmetry of device structure. This article provides more references for the design and performance optimization of the lateral IMPATT devices.

The diffusion inversion problem seeks to recover the latent generative trajectory of a diffusion model given a real image. Faithful inversion is critical for ensuring consistency in diffusion-based image editing. Prior works formulate this task as a fixed-point problem and solve it using numerical methods. However, achieving both accuracy and efficiency remains challenging, especially for few-step models and novel samples. In this paper, we propose ***PreciseInv***, a general-purpose test-time optimization framework that enables fast and faithful inversion in as few as two inference steps. Unlike root-finding methods, we reformulate inversion as a learning problem and introduce a dynamic programming-inspired strategy to recursively estimate a parameterized sequence of noise embeddings. This design leverages the smoothness of the diffusion latent space for accurate gradient-based optimization and ensures memory efficiency via recursive subproblem construction. We further provide a theoretical analysis of ***PreciseInv***'s convergence and derive a provable upper bound on its reconstruction error. Extensive experiments on COCO 2017, DarkFace, and a stylized cartoon dataset show that ***PreciseInv*** achieves state-of-the-art performance in both reconstruction quality and inference speed. Improvements are especially notable for few-step models and under distribution shifts. Moreover, precise inversion yields substantial gains in editing consistency for text-driven image manipulation tasks. Code is available at: https://github.com/panda7777777/PreciseInv

Recent work shows that features from Stable Diffusion (SD) and contrastively pretrained models like DINO can be directly used for zero-shot semantic correspondence via naive feature concatenation. In this paper, we explore the stronger potential of Stable Diffusion 3 (SD3), a rectified flow-based model with a multimodal transformer backbone (MM-DiT). We show that semantic signals in SD3 are scattered across multiple timesteps and transformer layers, and propose a multi-level fusion scheme to extract discriminative features. Moreover, we identify that naive fusion across models suffers from inconsistent distributions, thus leading to suboptimal performance. To address this, we propose a simple yet effective confidence-aware feature fusion strategy that re-weights each model’s contribution based on prediction confidence scores derived from their matching uncertainties. Notably, this fusion approach is not only training-free but also enables per-pixel adaptive integration of heterogeneous features. The resulting representation, Fuse2Match, significantly outperforms strong baselines on SPair-71k, PF-Pascal, and PSC6K, validating the benefit of combining SD3, SD, and DINO through our proposed confidence-aware feature fusion. Code is available at https://github.com/panda7777777/fuse2match

In this article, a lateral AlGaN/GaN high-electron-mobility avalanche-transit-time (HEMATT) transistor based on the gate-structure (G-HEMATT) is first demonstrated. The presence of the gate changes the avalanche generation location and alters the current path to form a new effective channel for the avalanche transport mode, so the characteristics of G-HEMATT can be modulated according to the gate location. Our simulations show that the G-HEMATT exhibits better characteristics in terms of operating frequency, conversion efficiency, and AC power. The presence of the gate creates and changes the length of the dead zone, thus modulating the effective channel of the avalanche-transit mode. Compared to the HEMATT in this article, the optimum frequency of the G-HEMATT rises from 360 to 480 GHz, the maximum AC output power rises from 1.96 to 4.61 W/mm, and the maximum conversion efficiency rises from 11.21% to 22.03%. It is also found that the existence of the gate structure allows the formation of the new conducting channel between the gate and the drain, but the gate voltage has no significant effect on the device performance. The results also show that the sheet concentration of the channel two-dimensional electron gas (2-DEG) has a large effect on the performance of G-HEMATT, it is essential to ensure that the sheet concentration is not too low in order to obtain a more effective improvement in device performance.

In this paper, three polytypes of p-(6H, 4H, 3C)SiC and n-GaN heterojunction single-drift (SDR), and double-drift (DDR) impact-ionization-avalanche-transit-time (IMPATT) diodes are studied. We conduct the numerical simulations of the direct current (DC), radio frequency (RF), and noise characteristics of IMPATT diodes The results show that (6H)SiC/GaN IMPATT diodes have the optimum RF characteristics. Among them, the RF power density of (6H)SiC/GaN DDR IMPATT diode can reach 2.23 MW/cm2. The DC-RF conversion efficiency of (6H)SiC/GaN SDR IMPATT diode can reach 23.4%. Their noise performances are being examined in the meantime. The (3C)SiC/GaN IMPATT has better noise characteristics in the SDR structure, while (4H)SiC/GaN IMPATT has better noise characteristics in the DDR structure. This study provides a reference for the design and fabrication of IMPATT diodes.

The weakness of supervision and management measures in railway emergency rescue led to difficulties of whole of monitoring and disposal on the completion time and effect. In order to solve this problem, the GERTS stochastic network schedule is introduced to the process supervision of railway emergency rescue based on the analysis of process of railway emergency rescue. With critical procedures serving as the nodes and execution process as the edges of the network, the random network model is thus formed. In case of emergency, the simulation of GERTS random network can be used to predict necessary rescue time and disposal efficiency, with previous rescue time and effect for reference. The analysis of the case shows that the simulation obtained by this method is consistent with the practical situation of the rescue. Measure standards from this method can be acquired to evaluate the work schedule and efficiency, efficiently supervising the delay of different divisions during the rescue. The proposed measure improves the efficiency and handling capacity of railway emergency rescue, having certain theoretical guidance significance and application value on railway emergency rescue.

In this contribution, we propose and study a bufferaided opportunistic routing (BOR) scheme, which combines the benefits of both opportunistic routing and multihop diversity (MHD) aided transmissions. It was conceived for a buffer-aided three-node network (B3NN) composed of a source node (SN), a buffer-aided relay node (RN) and a destination node (DN). In this network, there are three channels namely the SN-RN, RN-DN and SN-DN channels. The key motivation is that we are aiming for activating the specific channels requiring a recuded energy dissipation. In order to study this problem, a three-dimensional (3D) transmission activation probability space (TAPS) is proposed, which is divided into four regions representing each of the three channels plus an outage region. In a specific time slot (TS), the instantaneous channel fading values may be directly mapped to a specific point in this 3D channel space. The BOR scheme then relies on the position of this point to select the most appropriate channel for its transmission. Both the energy dissipation and the outage probability (OP) are investigated for transmission in this network. The results show that when the system is operated at a normalized throughput of 0.4 packet/TS, the energy dissipation was reduced by 24.8% to 77.6% compared to three different benchmark schemes. Alternatively, our technique is capable of reducing the OP by 89.6% when compared to conventional opportunistic routing. As in all buffer-aided system, the performance improved with the cost of higher packet delay, which is also studied.

In multihop diversity aided multihop links, the number of bits transmitted in each Time Slot (TS) is affected by both the Channel Quality (CQ) and the Buffer Fullness (BF), when adaptive modulation is employed. We assume that every node has buffers for temporarily storing its received packets for further transmission at instances of good CQ. For the sake of improving the throughput, a Maximum Throughput Adaptive Rate Transmission (MTART) scheme was proposed, where the specific hop having the capability of transmitting the highest number of bits (packets) will be activated. If more than one hops are capable of transmitting the same number of bits, the particular hop having the highest CQ (reliability) is activated. We demonstrate that the MTART scheme has 8 dB gain at the Outage Probability (OP) of 10-3and has 3 dB gain in terms of the throughput attained in comparison to the conventional adaptive modulation aided scheme.

In this paper buffer-aided Opportunistic Routing (OR) was designed with the aid of the novel concept of linear Transmission Activation Probability Space (TAPS) partitioning invoked for relay-assisted networks, which combines the benefits of both OR [1] and of buffer-aided transmissions [2]. More specifically, a packet may be transmitted from the Source Node (SN) to the Destination Node (DN) either directly or indirectly via one of theMRelay Nodes (RNs), depending on the instantaneous channel qualities. The above-mentioned linear multi-dimensional TAPS partitioning concept is proposed for partitioning the transmission space into (2M+1) transmission regions plus an outage region, while ensuring that the number of input packets is equal to the number of output packets at each RN's buffer. The benefit of having a buffer and tolerating the associated delay is that the best channel is activated for transmission based on our linear TAPS partitioning method.

A buffer-aided two hop link is studied, where the RN is capable of temporarily storing the received packets. We commerce by defining the concept of a two-dimensional Channel Probability Space (CPS) based on the source-relay and relay-destination channel. Specifically, a non-linear CPS division method is proposed, which partitions the CPS into several regions representing the quality of the specific channels plus an outage region. Then the best channel is activated for the sake of minimizing the system's energy dissipation. Finally, the proposed buffer-aided transmission scheme relying on our non-linear CPS division regime is investigated and the results show that at given average end-to-end energy dissipation, the outage probability was reduced by 33.5% compared to the benchmark scheme.

Most of the nodes in ad hoc networks rely on batteries, which requires energy saving. Hence, numerous energy-efficient routing algorithms have been proposed for solving this problem. In this paper, we exploit the benefits of cross-layer information exchange, such as the knowledge of the Frame Error Rate (FER) in the physical layer, the maximum number of retransmissions in the Medium Access Control (MAC) layer and the number of relays in the network layer. Energy-consumption-based Objective Functions (OF) are invoked for calculating the end-to-end energy consumption of each potentially available route for both Traditional Routing (TR) and for our novel Opportunistic Routing (OR), respectively. We also improve the TR and the OR with the aid of efficient Power Allocation (PA) for further reducing the energy consumption. For the TR, we take into account the dependencies amongst the links of a multi-hop route, which facilitates a more accurate performance evaluation than upon assuming the links that are independent. Moreover, two energy-efficient routing algorithms are designed based on Dijkstra's algorithm. The algorithms based on the energy OF provide the theoretical bounds, which are shown to be close to the bound found from exhaustive search, despite the significantly reduced complexity of the former. Finally, the end-to-end throughput and the end-to-end delay of this system are analyzed theoretically and a new technique of characterizing the delay distribution of OR is proposed. The simulation results show that our energy-efficient OR outperforms the TR and that their theoretical analysis accurately matches the simulation results.

In ad hoc networks the nodes actively and voluntarily participate in constructing a network and act as relays for other nodes. As a result of node-mobility, the Channel State Information (CSI) varies and hence a substantial amount of control messages have to be exchanged across the network to maintain reliable communications between certain pairs of nodes, which potentially imposes a high energy-consumption. Therefore, minimizing the energy consumption and maximizing the throughput of ad hoc nodes is extremely important. This paper analyzes both the energy consumption and the achievable throughput of a multihop route by exploiting both the CSI quantified, for example in terms of the Frame Error Ratio (FER), as well as the number of Medium Access Control (MAC) retransmissions and the number of hops. Since using limited number of MAC retransmissions in a hop-by-hop retransmission mode imposes dependencies amongst the links of a multi-hop route, a more accurate objective function may be formulated than that which assumes the availability of an infinite number of retransmissions and which considers the links to be independent. Our simulations confirm the improved accuracy of the proposed Objective Function (OF), especially when the FER and the number of hops are high and the number of MAC retransmissions is low. Additionally, a low-complexity routing algorithm is designed, which carries out routing decisions based on the energy consumption predicted by the OF, and strikes a compromise between having 'few long-distance hops' and 'many short-distance hops' for the sake of energy minimization and throughput maximization.

The nodes of ad hoc networks are typically battery-powered, hence requiring the employment of energy-efficient schemes. Near-capacity coding schemes allow a single link to communicate using the lowest possible transmit power, while achieving a low Frame Error Ratio (FER). With the same motivation of conserving battery energy, numerous power-aware routing algorithms have been proposed for improving the overall multiuser network's energy-efficiency instead of improving a single link. Taking both these design factors into consideration, we employ Multi-Antenna aided Relays (MA-Rs) in the context of ad hoc networks, which use a three-stage concatenated transceiver constituted by an Irregular Convolutional Code, Unity-Rate Code and Space-Time Trellis Code (IrCC-URC-STTC) equipped with two antennas. All other mobiles are single-antenna assisted nodes and refrain from relaying, hence they dispense with STTC schemes and use a two-stage concatenated IrCC-URC coding scheme. It is confirmed that as expected, in a high-node-density scenario the average energy consumption per information bit and per node becomes about a factor two lower than that in the equivalent Single-Antenna Relay (SA-R) aided networks.

The classic Dynamic Source Routing (DSR) protocol opts for the route requiring the lowest number of hops for transmitting data from the source to the destination. However, owing to node mobility in dynamic self-organizing ad hoc networks, the route containing a low number of potentially long-range hops does not always perform well. Furthermore, the currently used route may break owing to node-mobility and the routing information gathered during route discovery may become invalid. In order to circumvent the potentially inaccurate nature of the routing information, a fuzzy logic aided technique is incorporated into the routing algorithm for mitigating the influence of imprecise routing information. As a further benefit, fuzzy logic aided techniques are capable of processing multiple inputs, hence we use both the expected route lifetime and the number of hops as its input parameters, which allows us to integrate the physical layer and network layer into a jointly designed routing protocol. The route life-time is typically reduced with the increased mobility of the nodes. The specific route having the highest route 'stability' is finally selected for data transmission, and based on the route life-time the route-cache expiration time is adjusted adaptively. We will demonstrate that the proposed fuzzy logic based DSR outperforms the conventional DSR in terms of the attainable network throughput, despite having a lower network control load. Finally, we quantify the impact of the physical layer on the achievable performance of the network layer for different physical layer schemes by using the OMNeT++ simulator.