Asymptotic Stability of Impulsive Cellular Neural Networks with Infinite Delays via Fixed Point Theory

We employ the new method of fixed point theory to study the stability of a class of impulsive cellular neural networks with infinite delays. Some novel and concise sufficient conditions are presented ensuring the existence and uniqueness of solution and the asymptotic stability of trivial equilibrium at the same time. These conditions are easily checked and do not require the boundedness and differentiability of delays

Characteristics and Development Mechanisms of Northeast Cold Vortices

The northeast cold vortices (NECVs) in May-September during 1989–2018 are classified, based on the 6 h NCEP/NCAR reanalysis data (2.5° × 2.5°) and observational data from the Meteorological Information Comprehensive Analysis and Process System (MICAPS) provided by China Meteorological Administration. Meanwhile, characteristics and development mechanisms for NECVs of different types are also analyzed. In the recent 30 years, the occurrences of NECV processes have been increasing year by year, with an average of 7.4 times per year in Northeast China and a duration of 3–5 days on average for each process. NECVs mostly occur in late spring and early summer, and the longest time influenced by NECVs exceeds 19 days, with annual means of 9.9 days, 8.8 days, and 7.0 days in May, June, and July, respectively. The frequency of weak NECVs is about 1.2 times that of strong NECVs. Strong NCVs in late spring and early autumn as well as weak MCVs in summer are with high-frequency occurrences. It is found that when NCVs occur in late spring and early autumn, the upper-level westerly jets are relatively stronger, thus strengthening the divergence in the upper troposphere and the vortex circulation. The circulation fields in upper and lower levels cooperate with the strong jets, promoting the continuous development and maintenance of the cold vortices. Apart from the jets and circulation, the lower central potential height combined with the obvious cold-core and stronger ascending motions favor the NCV’s development. In addition, the dry intrusion has a strong promotion due to the stronger lower-level cold advection and downward intrusion of high potential vorticity. However, when MCVs occur in summer, things are just the opposite

Accelerated Degradation Model of Nonlinear Wiener Process Based on Fixed Time Index

In the process of extrapolating a lifetime distribution function under normal storage conditions through nonlinear accelerated degradation data, time indexes under the normal storage conditions are usually set to the mean value of time indexes under various accelerated stresses. However, minor differences in time indexes may lead to great changes in the assessment results. For such a problem, an accelerated degradation model of a nonlinear Wiener process based on a fixed time index is established first and meanwhile, the impact of the measurement error is considered. Then, the probability density function is normalized, and multiple unknown parameters are estimated by using fminsearch function in MATLAB and multiple iterations. Finally, the model is validated by accelerated degradation test data of accelerometers and the O-type rubber sealing rings. The results show that there is a difference of 30,710 h for accelerometers between the mean time to failure under normal storage conditions obtained by the proposed method and the mean time to failure when the time indexes are the mean value of those under various accelerated stresses, and the main cause of the difference is compared and analyzed. A similar phenomenon is observed in the case study of O-type rubber sealing rings

Proceedings of PVP2007 2007 ASME Pressure Vessels and Piping Division Conference Online AE Inspection and Safety Assessment of Vertical Storage Tank

Abstract With the rapid growth of the global petroleum industry and continuous increase of energy demand, the crude oil and product oil reserve has been given a general concern in every country, and the requirements for the reserve capacity of various types of petroleum storage depots become higher and higher, therefore, the quantity of various types of storage tanks is increasing dramatically. At present, 100,000m 3 storage tank has become the primary structure for construction of crude oil storage tanks for Chinese petrochemical industry. Large vertical metal storage tank features large capacity, central distribution, storage of inflammable, explosive and toxic media etc., leakage or explosion accident, once happens, often results in disastrous consequence and severe environmental pollution, which brings a huge loss and hazard to social economy, production and people's living. The major cause for the accidents of storage tanks is corrosion and leakage, the external corrosion is mainly the soil corrosion and moist atmospheric corrosion of outer wall of oil tank baseplate; the internal corrosion is the corrosion of tank bottom, tank wall and tank top. Among the above corrosions, the most hard to treat is the corrosion of tank baseplate. In this paper through laboratory simulation of AE tests of leakage of storage tank and corrosion of baseplate and comparison between online AE inspection of more than 30 large vertical storage tanks and shutdown inspection of part of storage tanks, the matters about online AE inspection techniques for corrosion and leakage of storage tank baseplate and safety assessment of vertical storage tank are discussed, online AE inspection technique and assessment standard fit for China's present condition are proposed, the safety class and corresponding shutdown inspection cycle of vertical storage tank are determined, the storage tanks where no problems are found by online AE inspection continue their service, whereas the storage tanks where severe problems are found are shut down for inspection, thus the contradiction between shutdown inspection and safe production is basically solved

Novel ADCs and combination therapy in urothelial carcinoma: latest updates from the 2023 ASCO-GU Cancers Symposium

Abstract Antibody–drug conjugates (ADCs) combine the cytotoxicity of small-molecule drugs with antibody targeting. Due to their precise and powerful effect, they have become a new hotspot and an important trend in the research and development of anti-tumor antibody drugs. Every year, exciting new developments and innovations in the treatment of urological tumors are introduced at the American Society of Clinical Oncology-Genitourinary (ASCO-GU) Cancers Symposium. In this article, we summarize some of the most impressive advances in new clinical trials and clinical data on ADCs in the 2023 ASCO-GU Cancers Symposium for the treatment of urothelial carcinoma

Assessing the impact of Chinese FY-3/MERSI AOD data assimilation on air quality forecasts: Sand dust events in northeast China

Summarization: Aerosol optical depth (AOD) is an important parameter characterizing the optical properties of atmospheric aerosols and can be used to indicate aerosol loading and evaluate air quality. In this study, a FY-3/medium-resolution spectral imager (MERSI) AOD data assimilation (DA) system was developed using a three-dimensional variational DA method to assess the impact of Chinese FY-3/MERSI AOD data assimilation on air quality forecasts. Two typical sand-dust weather events occurred during the spring season of years 2010 and 2011 were selected as case study. The DA system and Weather Research and Forecasting model coupled with a chemical model (WRF-Chem) were used to evaluate the impacts of FY-3/MERSI AOD DA on air quality forecasts. This was based on comparisons between modeled AOD data and AOD data acquired by the Aerosol Robotic Network (AERONET) and Moderate Resolution Imaging Spectroradiometer (MODIS) satellites. Results from both case studies revealed that FY-3/MERSI AOD DA apparently improved the air quality forecasts. Key findings of the FY-3/MERSI AOD DA experiments included: (1) FY-3/MERSI AOD DA adjusted the simulated aerosol particle content of the WRF-Chem model and efficiently improved the extinction coefficient fields below 500 hPa. Moreover, AOD DA had the strongest effect on adjusting the extinction coefficients at 750 hPa (approximately 2 km). Compared with the AOD background field, the AOD analysis field was similar to the satellite observation field. (2) Compared with the control experiments without DA, the AOD DA experiment produced more accurate 24-h AOD forecasts, more consistent with the AERONET and satellite observations. (3) Due to the spatial distribution and intensity difference of satellite AOD data, satellite AOD data assimilation has obvious individual characteristics for the improvement of particle concentration prediction. Our study findings suggest that the developed DA system can facilitate the effective use of AOD data acquired by Chinese satellites in air quality forecasting models and can improve dust forecasting results.Παρουσιάστηκε στο: Atmospheric Environmen

Large scale operational soil moisture mapping from passive MW radiometry: SMOS product evaluation in Europe & USA

Summarization: Earth Observation (EO) allows deriving from a range of sensors, often globally, operational estimates of surface soil moisture (SSM) at range of spatiotemporal resolutions. Yet, an evaluation of the accuracy of those products in a variety of environmental conditions has been often limited. In this study, the accuracy of the SMOS SSM global operational product across 2 continents (USA, and Europe) and a range of land use/cover types is investigated. SMOS predictions were compared against near concurrent in-situ SSM measurements from the FLUXNET observational network. In total, 7 experimental sites were used to assess the accuracy of SMOS derived soil moisture for 2 complete years of observations (2010–2011). The accuracy of the SMOS SSM product is investigated in different seasons for the seasonal cycle as well as different continents and land use/cover types. Results showed a generally reasonable agreement between the SMOS product and the in-situ soil moisture measurements in the 0–5 cm soil moisture layer. Root Mean Square Error (RMSE) in most cases was close to 0.1 m3 m−3 (minimum 0.067 m3 m−3). With a few exceptions, Pearson's correlation coefficient was found up to approx. 55%. Grassland, shrublands and woody savanna land cover types attained a satisfactory agreement between satellite derived and in-situ measurements but needleleaf forests had lower correlation. Better agreement was found for the grassland sites in both continents. Seasonally, summer and autumn underperformed spring and winter. Our study results provide supportive evidence of the potential value of this operational product for meso-scale studies in a range of practical applications, helping to address key challenges present nowadays linked to food and water security.Παρουσιάστηκε στο: International Journal of Applied Earth Observation and Geoinformatio