As one of the promising technologies, reconfigurable intelligent surface (RIS) and simultaneous transmitting and reflecting RIS (STAR-RIS) have attracted great interest. However, the existing RISs offer broadband tuni...
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As one of the promising technologies, reconfigurable intelligent surface (RIS) and simultaneous transmitting and reflecting RIS (STAR-RIS) have attracted great interest. However, the existing RISs offer broadband tuning capability without filtering function due to the absence of radio frequency (RF) units, which easily leads to the unexpected tuning of the RIS undesired signals, especially in large-scale deployments. For the target network, it is difficult to obtain the parameter settings of RISs to serve other networks, which causes the unpredictability of the wireless environment. In this paper, we consider the covert communication in a STAR-RIS assisted random wireless network with randomly distributed blockages. We investigate the impact of STAR-RIS large-scale deployment on covert communication and leverage its inherent unpredictability for improving the covertness. We derive the average detection error probability for warden within the random wireless networks. Furthermore, we optimize the passive beamforming of STAR-RIS to maximize the covert communication rate, considering both direct and indirect line-of-sight (LoS) links. To address this, we employ an alternating optimization (AO) algorithm based on the semi-definite programming (SDP) method. Finally, numerical results demonstrate significant enhancements and increase covert capability achieved through the large-scale deployment of STAR-RIS. 2002-2012 IEEE.
Plasma immersion ion implantation (PIII) is an efficient method for fabricating high-quality p+/n diodes with junction depths below 100 nm. SiF4 is implanted to create an amorphous Si layer to retard B channeling and ...
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Plasma immersion ion implantation (PIII) is an efficient method for fabricating high-quality p+/n diodes with junction depths below 100 nm. SiF4 is implanted to create an amorphous Si layer to retard B channeling and diffusion, and then BF3 is implanted. Ultrashallow p+/n junctions are formed by annealing at 1060-degrees-C for 10 s. With the shallow implants, no extended defects are observed in device or peripheral areas due to rapid outdiffusion of fluorine. Diode electrical characteristics yield forward ideality factor of 1.05-1.06 and leakage current density below 2 nA/cm2 in the diode bulk. Minority-carrier lifetime below the junction is greater than 250 mus.
A simple fixed structure learning scheme is proposed for priority assignment at a single-server queue. The server processes two streams of jobs, with random service times (exponentially distributed) in which the param...
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A simple fixed structure learning scheme is proposed for priority assignment at a single-server queue. The server processes two streams of jobs, with random service times (exponentially distributed) in which the parameters are unknown at the start. The optimal priority assignment is asymptotically learned with arbitrary accuracy by properly choosing the algorithm parameters. The scheme has finite memory and is easily implementable. Simulations results are included.
To maximize the effectiveness of wearable systems in mobile computing environments, interface design must be carefully matched with user tasks. By constructing mental models of user actions, interface elements may be ...
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To maximize the effectiveness of wearable systems in mobile computing environments, interface design must be carefully matched with user tasks. By constructing mental models of user actions, interface elements may be chosen and tuned to meet the specific software and hardware requirements of specific procedures. This article details specific cases of task study and interface implementation by the Carnegie Mellon University (CMU) wearable computer project over six generations of systems. An abstract model for application interface design is given, with examples of implementation on both embedded systems and general purpose platforms. It describes the factors of human interface in wearable systems design focusing on how the application impacts the design and especially the user interface. First examined is the process of modeling specific user tasks, and establishing a linkage with the system interface that closely mirrors this model. Next is an overview of the VuMan embedded systems, followed by a description of the Navigator general-purpose machines. The article concludes with a summary of information developed through the design and testing of these wearable systems.
This note uses an integral constraint on the closed-loop transfer function of unstable open-loop systems to quantify a tradeoff between feedback properties of the closed-loop system.
This note uses an integral constraint on the closed-loop transfer function of unstable open-loop systems to quantify a tradeoff between feedback properties of the closed-loop system.
Large language models (LLMs) have made significant progress in general-purpose natural language processing tasks. However, LLMs are still facing challenges when applied to domain-specific areas like telecommunications...
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Establishing a precise intake pressure environment in the aeropropulsion systems test facility (ASTF) is critical for evaluating aeroengines' flight characteristics. The model-partial and robust active disturbance...
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Spectacular naturally occurring bursts of X-rays with tens of mega electron-volt energies are observed in association with lightning activity in the Earth's atmosphere. These events were first discovered in 1994 b...
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ISBN:
(数字)9781946815200
ISBN:
(纸本)9798331513979
Spectacular naturally occurring bursts of X-rays with tens of mega electron-volt energies are observed in association with lightning activity in the Earth's atmosphere. These events were first discovered in 1994 by NASA's Compton Gamma Ray Observatory [Fishman et al., 1994] and are commonly referred to as terrestrial gamma-ray flashes (TGFs). Although since then many other orbital observatories captured these high energy events [Smith et al., 2005; Marisaldi et al., 2010; Briggs et al., 2011; Neubert et al., 2020] and these events have been clearly linked to very intense but short (approximately 10–50 microseconds) bursts of electromagnetic radiation [Ostgaard et al., 2021], the physical nature of these events remains unclear. It is widely recognized that these electromagnetic bursts are also the strongest naturally occurring sources of terrestrial very high frequency (VHF) radiation [Jacobson et al., 2012]. The most puzzling unexplained aspect of these events is that the extreme gamma ray and electromagnetic energy fluxes originate from very compact regions with spatial extent on the order of 100 meters [Lu et al., 2010; Rison et al., 2016; Tilles et al., 2019; Tilles et al., 2020; Kohn et al., 2020; Heumesser et al., 2021], yet they are light-deficient and often even optically undetectable compared to ordinary lightning discharges [Jacobson et al., 2012]. In this work we report on the mechanism that allows precise quantitative explanation of the vast majority of currently accumulated observations of these events at different altitudes in the Earth's atmosphere. The specifics includes TGF fluences and durations, optical darkness, magnitudes and specific waveform characteristics of low and very low frequency radio emissions termed narrow bipolar events and energetic in cloud pulses that are associated with TGFs, the peculiar observations of very fast (typically one tenths of the speed of light) spatial propagation features termed fast positive breakdown in the prese
Empathy detection (ED) and empathy intent classification (EIC) aim to identify the empathy direction expressed in user utterances and the underlying empathy intent behind them. Previous studies show that facilitating ...
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ISBN:
(数字)9798350368741
ISBN:
(纸本)9798350368758
Empathy detection (ED) and empathy intent classification (EIC) aim to identify the empathy direction expressed in user utterances and the underlying empathy intent behind them. Previous studies show that facilitating information transfer between tasks can enhance model performance. However, the interaction between ED and EIC in few-shot learning remains underexplored. To this end, we identify the challenges in jointly training ED and EIC in a few-shot setting: establishing effective information transfer between them and improving the model’s generalization capability. We propose a novel model called USB. For information transfer, the interactive module maps empathy and empathy intent labels through utterances to model task correlations. For generalization capability, after capturing empathy and empathy intent representations with an adaptive fusion module, we introduce a multi-level contrastive learning strategy to optimize representations at task and label levels, enhancing generalization. Experimental results on two public datasets show that our model outperforms all baselines.
Growth of CuGaS2 bulk crystals by the temperature difference method under controlled S vapor pressure has been investigated. The synthesized crystals were CuGaxIn1-xS2 solid solutions, and the In alloy composition, 1-...
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Growth of CuGaS2 bulk crystals by the temperature difference method under controlled S vapor pressure has been investigated. The synthesized crystals were CuGaxIn1-xS2 solid solutions, and the In alloy composition, 1-x, depended on both the growth temperature and the S vapor pressure.
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