11 research outputs found
Experimental Investigation on Motions of Immersing Tunnel Element under Irregular Wave Actions
On the Robustness of ChatGPT: An Adversarial and Out-of-distribution Perspective
ChatGPT is a recent chatbot service released by OpenAI and is receiving
increasing attention over the past few months. While evaluations of various
aspects of ChatGPT have been done, its robustness, i.e., the performance to
unexpected inputs, is still unclear to the public. Robustness is of particular
concern in responsible AI, especially for safety-critical applications. In this
paper, we conduct a thorough evaluation of the robustness of ChatGPT from the
adversarial and out-of-distribution (OOD) perspective. To do so, we employ the
AdvGLUE and ANLI benchmarks to assess adversarial robustness and the Flipkart
review and DDXPlus medical diagnosis datasets for OOD evaluation. We select
several popular foundation models as baselines. Results show that ChatGPT shows
consistent advantages on most adversarial and OOD classification and
translation tasks. However, the absolute performance is far from perfection,
which suggests that adversarial and OOD robustness remains a significant threat
to foundation models. Moreover, ChatGPT shows astounding performance in
understanding dialogue-related texts and we find that it tends to provide
informal suggestions for medical tasks instead of definitive answers. Finally,
we present in-depth discussions of possible research directions.Comment: Technical report; code is at:
https://github.com/microsoft/robustlear
Effects of Thermal Discharge from Coastal Nuclear Power Plants and Thermal Power Plants on the Thermocline Characteristics in Sea Areas with Different Tidal Dynamics
The thermal discharge from coastal nuclear power plants and thermal power plants (CNATPP) not only increases the water temperature, but it also stratifies the seawater. Comprehending the characteristics of stratification that is caused by thermal discharge constitutes the basis for developing a comprehensive understanding of how thermal discharge affects marine organisms. The spatial and temporal characteristics of seawater stratification induced by thermal discharge were analyzed on the basis of measured data while using two study areas with different tidal dynamics as examples. The results showed the following. (1) Thermal discharge influenced the area within 3 km of the outlet. (2) In the East China Sea (which has strong tidal dynamics), the most significant stratification occurred 0.5 km–1.0 km from the outlet; however, in the South China Sea (which has weak tidal dynamics), the degree of stratification decreased with increasing distance from the outlet. (3) In the East China Sea (i.e., strong tidal dynamics), the depth of the thermocline during ebb tide gradually moved upward, while that during flood tide gradually moved downward, and the opposite was observed in the South China Sea (i.e., weak tidal dynamics). Finally, (4) the thermocline that was caused by thermal discharge mostly occurred at water depths above 7 m
Load Power Oriented Large-Signal Stability Analysis of Dual-Stage Cascaded dc Systems Based on Lyapunov-Type Mixed Potential Theory
Dual-stage cascaded dc systems are some of the most widely applied power interfaces in dc distributed power systems. However, in some practical situations, these systems might be unstable, especially if they incorporate tightly regulated load converters that operate as constant power loads (CPLs), whose power fluctuations could exert a cascading impact on the operation of the systems. Existing studies tend to describe the instability phenomena using bifurcation diagram analysis and the loci of eigenvalue analysis. However, it is usually difficult to derive the explicit expressions of the stability criterion. This paper addresses the large-signal stability issue of the dual-stage cascaded dc systems from a standpoint of load power and obtains the explicit form large-signal stability boundary in terms of load power by using Lyapunov-type mixed potential theory. Moreover, the prototype dual-stage cascaded dc system, in which the control strategies for the feeder converter and the load converter are different, is used as an example in this study. According to the results, the system remains stable when the load power is in [5.8, 23.2] W. When load power is less than 5.8 W or increased to [23.2, 32.8] W, the system is in a period-2 subharmonic oscillation state. Moreover, when the load power exceeds 32.8 W, the system falls into a chaotic state. The deduced boundary is highly consistent with the analysis results of both a bifurcation diagram and Jacobian matrix based analysis. Finally, both circuit-level simulation and experimental results validate the effectiveness of the load power stability boundary
Load Power Oriented Large-Signal Stability Analysis of Dual-Stage Cascaded dc Systems Based on Lyapunov-Type Mixed Potential Theory
Dual-stage cascaded dc systems are some of the most widely applied power interfaces in dc distributed power systems. However, in some practical situations, these systems might be unstable, especially if they incorporate tightly regulated load converters that operate as constant power loads (CPLs), whose power fluctuations could exert a cascading impact on the operation of the systems. Existing studies tend to describe the instability phenomena using bifurcation diagram analysis and the loci of eigenvalue analysis. However, it is usually difficult to derive the explicit expressions of the stability criterion. This paper addresses the large-signal stability issue of the dual-stage cascaded dc systems from a standpoint of load power and obtains the explicit form large-signal stability boundary in terms of load power by using Lyapunov-type mixed potential theory. Moreover, the prototype dual-stage cascaded dc system, in which the control strategies for the feeder converter and the load converter are different, is used as an example in this study. According to the results, the system remains stable when the load power is in [5.8, 23.2] W. When load power is less than 5.8 W or increased to [23.2, 32.8] W, the system is in a period-2 subharmonic oscillation state. Moreover, when the load power exceeds 32.8 W, the system falls into a chaotic state. The deduced boundary is highly consistent with the analysis results of both a bifurcation diagram and Jacobian matrix based analysis. Finally, both circuit-level simulation and experimental results validate the effectiveness of the load power stability boundary
Typhoon Soudelor (2015) Induced Offshore Movement of Sand Dunes and Geomorphological Change: Fujian Coast, China
Coupling Relationship of Geomorphic Evolution and Marine Hydrodynamics in the Stage-Specific Development of Urban Bays: A Modelling Case Study in Quanzhou Bay (1954–2017), China
With the development of social economy and human activities, the geomorphology and hydrodynamic conditions of coasts have been dramatically changed, causing serious environmental pollution and resource depletion. Taking Quanzhou Bay as an example, this study combined geomorphologic change with a hydrodynamic model to simulate the change in tidal currents in different periods. The results show a change in the coastline was the main cause of hydrodynamic change during the industrialization reform. During the past 70 years, the tidal prism decreased year by year, and the average velocity of the tidal current in the channel decreased by 33.7% and 30.8% at flood and ebb tide, respectively. In the early stages of industrialization, reclamation land was used in a single way. The tidal prism decreased by 22.2% and 29.8% in the spring and neap tide, respectively. In the middle and later stages, the tidal current velocity increased, and reclamation land was used in a variety of ways. In modern society, the reclamation land-use type was unitary. Based on this research, we show the influence of human activities on the evolution of the bay’s geomorphology and provide suggestions for the management of the bay
Coupling Relationship of Geomorphic Evolution and Marine Hydrodynamics in the Stage-Specific Development of Urban Bays: A Modelling Case Study in Quanzhou Bay (1954–2017), China
With the development of social economy and human activities, the geomorphology and hydrodynamic conditions of coasts have been dramatically changed, causing serious environmental pollution and resource depletion. Taking Quanzhou Bay as an example, this study combined geomorphologic change with a hydrodynamic model to simulate the change in tidal currents in different periods. The results show a change in the coastline was the main cause of hydrodynamic change during the industrialization reform. During the past 70 years, the tidal prism decreased year by year, and the average velocity of the tidal current in the channel decreased by 33.7% and 30.8% at flood and ebb tide, respectively. In the early stages of industrialization, reclamation land was used in a single way. The tidal prism decreased by 22.2% and 29.8% in the spring and neap tide, respectively. In the middle and later stages, the tidal current velocity increased, and reclamation land was used in a variety of ways. In modern society, the reclamation land-use type was unitary. Based on this research, we show the influence of human activities on the evolution of the bay’s geomorphology and provide suggestions for the management of the bay