Diagnostic Studies of Non-Thermal Atmospheric Pressure Nanosecond Plasma Jets

Non-thermal atmospheric pressure plasma jets attract a lot of attentions due to its growing interest in plasma medicine. In this study, reactive species (e.g. excited He, O, OH) in a helium single-electrode non-thermal atmospheric pressure nanosecond plasma jet (APNPJ) driven by a nanosecond pulsed power supply have been studied via electrical measurements (e.g. voltage, current) and optical emission spectroscopy. It is shown that the gas temperature of the APNPJs remained near 300±50 K by fitting N2(C-B) second positive system and OH(A-X) emission spectrum. Higher excited N2+ (by a factor of 1.3) but less excited N2, He, O, and OH productions are observed when compared two APNPJs driven by a short pulse (5 ns pulse width) and a long pulse (164 ns), respectively. Importantly, comparable or more excited species were produced by the 5-ns pulsed plasma for the first 100 ns which implies shorter rise time of a pulsed voltage can influence the plasma chemistry by boosting the production of excited species. Further studies indicate that enhanced ionization near the single-electrode nozzle, earlier streamer formation and stronger emissions by excited N2, N2+, OH, and O are observed when the 164-ns plasma jet impinges onto the water surface. Interestingly, maximal OH(A-X) emissions are obtained at pulse width of 600 – 800 ns when a plasma jet impinges onto the water surface with examining of pulse widths from 200 ns to 5000 ns at 7 kV, 200 ns at 1 kHz. More importantly, temporally-resolved emission spectroscopy shows that more than 40% OH(A-X) emissions is produced during the first 200 ns of the voltage pulse regardless of the pulse width. Plume dynamics indicate that increasing both amplitude (ranging from 5 kV to 10 kV) and helium flow rate (from 8 SCCM to 164 SCCM) resulted in faster propagation of ionization fronts iii hence longer plasma plumes, meanwhile, higher repetition rate (from 10 Hz to 4 kHz) and longer pulse width (from 200 ns to 990 μs) created earlier inception of ionization fronts but shorter plume lengths. Study of repeatability of both air corona discharge and plasma jets pertinent to breakdown probability are investigated in further details

Regional Policies’ Impacts on Urban Migration:Evidence from Special Economic Zones in China

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Bond performance between NSM FRP rods and concrete using ECC as bonding materials

The pull-out test of near-surface-mounted (NSM) FRP (fiber-reinforced plastics) rod from concrete was performed using engineered cementitious composites (ECC) as bonding materials. The feasibility of cementitious materials in NSM FRP strengthened concrete was then analyzed. Carbon FRP (CFRP) rods and Basalt FRP (BFRP) rods with spiral surfaces and diameters of 8 mm were used in the test. The bonding lengths are 5 times and 10 times of the FRP diameter, respectively. Results show that the failure modes of all the specimens using ECC as bonding materials are pull-out of FRP rods with ductile behavior. Moreover, specimens with NSM FRP rods using epoxy are prepared as control specimens to evaluate the feasibility of ECC. For CFRP rods, the pull-out load-bearing capacity of specimens using ECC is 70% and 50% of that in specimens using epoxy for 5 times and 10 times of the FRP diameter, respectively. For BFRP rods, the load-bearing capacity of specimens using ECC is 75% and 55% of that in specimens using epoxy for 5 times and 10 times of the FRP diameter, respectively. Thus, ECC can be applied in NSM FRP strengthened concrete structures as the bonding materials

Effects of Pulse Width on He Plasma Jets in Contact with Water Evaluated by OH(A-X) Emission and OHaq Production

Nanosecond pulsed helium plasma jets impinging on water produce hydroxyl radicals both in gas- and liquid-phase. In this study, the effects of pulse width on a repetitively pulsed plasma jet in contact with water are evaluated via OH(A-X) emission and OHaq production in water for various pulse widths ranging from 200 to 5000 ns. The maximal energy efficiency of OH(A-X) emission is obtained for pulse widths of 600-800 ns whereas the maximal efficiency of OHaq production is at 200 ns. Temporally-resolved emission spectroscopy shows that more than 40% of OH(A-X) emission is produced during the first 200 ns of the voltage pulse regardless of the pulse width. An equivalent circuit model of the plasma jet impinging on water is compiled to understand the charge transfer process, which is important for OHaq production via charge exchange reactions

Applying Machine Learning Approach to Explore Childhood Circumstances and Self-Rated Health in Old Age - China and the US, 2020-2021.

INTRODUCTION: Childhood circumstances impact senior health, prompting the introduction of machine learning methods to assess their individual and collective contributions to senior health. METHODS: Using health and retirement study (HRS) and China Health and Retirement Longitudinal Study (CHARLS), we analyzed 2,434 American and 5,612 Chinese participants aged 60 and above. Conditional inference trees and forests were employed to estimate the influence of childhood circumstances on self-rated health (SRH). RESULTS: The conventional method estimated higher inequality of opportunity (IOP) values in both China (0.039, accounting for 22.67% of the total Gini coefficient 0.172) and the US (0.067, accounting for 35.08% of the total Gini coefficient 0.191). In contrast, the conditional inference tree yielded lower estimates (China: 0.022, accounting for 12.79% of 0.172; US: 0.044, accounting for 23.04% of 0.191), as did the forest (China: 0.035, accounting for 20.35% of 0.172; US: 0.054, accounting for 28.27% of 0.191). Childhood health, financial status, and regional differences were key determinants of senior health. The conditional inference forest consistently outperformed others in predictive accuracy, as demonstrated by lower out-of-sample mean squared error (MSE). DISCUSSION: The findings emphasize the need for early-life interventions to promote health equity in aging populations. Machine learning showcases the potential in identifying contributing factors

WIPI: A New Web Threat for LLM-Driven Web Agents

With the fast development of large language models (LLMs), LLM-driven Web Agents (Web Agents for short) have obtained tons of attention due to their superior capability where LLMs serve as the core part of making decisions like the human brain equipped with multiple web tools to actively interact with external deployed websites. As uncountable Web Agents have been released and such LLM systems are experiencing rapid development and drawing closer to widespread deployment in our daily lives, an essential and pressing question arises: "Are these Web Agents secure?". In this paper, we introduce a novel threat, WIPI, that indirectly controls Web Agent to execute malicious instructions embedded in publicly accessible webpages. To launch a successful WIPI works in a black-box environment. This methodology focuses on the form and content of indirect instructions within external webpages, enhancing the efficiency and stealthiness of the attack. To evaluate the effectiveness of the proposed methodology, we conducted extensive experiments using 7 plugin-based ChatGPT Web Agents, 8 Web GPTs, and 3 different open-source Web Agents. The results reveal that our methodology achieves an average attack success rate (ASR) exceeding 90% even in pure black-box scenarios. Moreover, through an ablation study examining various user prefix instructions, we demonstrated that the WIPI exhibits strong robustness, maintaining high performance across diverse prefix instructions

Transmission Congestion Management with Generalized Generation Shift Distribution Factors

A major concern in modern power systems is that the popularity and fluctuating characteristics of renewable energy may cause more and more transmission congestion events. Traditional congestion management modeling involves AC or DC power flow equations, while the former equation always accompanies great amount of computation, and the latter cannot consider voltage amplitude and reactive power. Therefore, this paper proposes a congestion management approach incorporating a specially-designed generalized generator shift distribution factor (GSDF) to derive a computationally-efficient and accurate management strategies. This congestion management strategy involves multiple balancing generators for generation shift operation. The proposed model is superior in a low computational complexity (linear equation) and versatile modeling representation with full consideration of voltage amplitude and reactive power.Comment: 5 pages, 4 figures. Accepted by conference: ICPES 202

Research Progress of Breast Tissue Marker Clips and Their Application in Neoadjuvant Therapy for Breast Cancer

Currently, breast cancer being of rapidly increasing incidence rates and as the most commonly diagnosed malignant tumor in breast surgery, has attracted much attention. Neoadjuvant therapy (NAT) has been proved to be beneficial for reducing tumor size and breast-conserving surgery. As a new type of metal localization marker, breast tissue marker clips can be used to precisely locate tumor tissue and improve cure rates. This review focuses on the marker clips and their significance in the diagnosis and treatment of neoadjuvant therapy for breast cancer, hoping to provide more clinical bases for research and promote this technology