Residual Test Method Research Articles

Detection and identification of bad data in AC/DC hybrid systems with LCC and MMC

Based on the CIM/XML and CIM/E documents exported from the regional dispatching system, this paper focuses on data generation and starts by converting the exported documents into raw input data for state estimation. Considering the interactions between the AC system, LCC, MMC, and LCC-MMC interfaces, a unified iterative method is proposed to model the state estimation of the 500 kV subnetwork. Subsequently, Gaussian noise is added to the original measurement data, and the maximum residual test method is employed for detecting and identifying bad data. Finally, the effectiveness of the proposed models for AC/DC state estimation and the detection and identification of bad data are validated through simulation data.

Analysis and prediction of thyroid cancer morbidity and mortality trends in China

Objective: To analyze the morbidity and mortality trends of thyroid cancer in China from 1990 to 2019, explore the causes of the trends, and predict morbidity and mortality in the future. Methods: The morbidity and mortality data of thyroid cancer in China from 1990 to 2019 were collected from the 2019 Global Burden of Disease database. The Joinpoint regression model was used to describe the change trends. Based on the morbidity and mortality data from 2012 to 2019, a grey model GM (1,1) was constructed to predict the trends in the next ten years. The model was tested by the posterior error method and residual test method. Results: In all populations, men and women, the AAPC values of the crude morbidity rates were 4.15% (95%CI: 3.86%-4.44%, P<0.001), 5.98% (95%CI: 5.65%-6.31%, P<0.001) and 3.23% (95%CI: 2.94%-3.53%, P<0.001) respectively, the AAPC values of age-standardized morbidity rates were 2.47% (95%CI: 2.12%-2.83%, P<0.001), 3.98% (95%CI: 3.68%-4.29%, P<0.001), 1.65% (95%CI: 1.38%-1.93%, P<0.001), the AAPC values of crude mortality rates were 2.09% (95%CI: 1.92%-2.25%, P<0.001), 3.68% (95%CI: 3.45%-3.90%, P<0.001), 0.60% (95%CI: 0.50%-0.71%, P<0.001). The age-standardized mortality rates in men showed a fluctuating trend of first decrease (1990-1994), then increase (1994-2012), and then decrease (2012-2019) (AAPC=1.35%, 95%CI: 1.16%-1.53%, P<0.001). The age-standardized mortality rate in women continuously decreased (AAPC=-1.70%, 95%CI: -1.82%- -1.58%, P<0.001). The GM (1,1) models can be used for medium and long-term predictions. The results of the residual test show that the average relative error values of all models are less than 10.00%, the prediction accuracy values are more than 80.00%, and the prediction effects are good. The results of the posterior error method show that all the prediction results are good except the qualified prediction of the age-standardized morbidity rate in men. In 2029, the crude morbidity rates would increase to 3.57/100 000, 2.78/100 000, and 4.40/100 000, respectively, and the age-standardized incidence rates would increase to 2.38/100 000, 1.89/100 000, and 2.88/100 000, respectively, the crude mortality rates would increase to 0.57/100 000, 0.62/100 000 and 0.53/100 000, and the age-standardized mortality rates would decrease to 0.33/100 000, 0.42/100 000 and 0.27/100 000 in all population, men and women in China. Conclusions: The overall, gender- specific age-standardized mortality rates showed downward trends in the last decade or so, and the prediction results showed that it might further decline. However, the crude morbidity rates, age-standardized and crude mortality rates have been on the rise, and the population aging is becoming increasingly serious in China, which requires close attention and targeted prevention and control measures.

Elevated temperature and post-fire stress-strain modeling of advanced high-strength cold-formed steel alloys

Advanced high-strength cold-formed steels (AHSS) have been developed with yield strengths up to 1250 MPa and ultimate strengths up to 1900 MPa. Accurate stress-strain modeling of these new steel alloys are required for eventual application of AHSS into the building construction industry, including the material behavior of AHSS subjected to elevated temperatures. A series of new constitutive material models are proposed based on the experimental AHSS stress-strain database at elevated temperatures (i.e., steady-state and transient-state test methods) and post-fire scenario (i.e., residual test method). The stress-strain curves from experiments on two families of AHSS, including dual phase steel with nominal yield strengths of 340 MPa and 700 MPa, and martensitic steel with nominal yield strengths of 1030 MPa and 1200 MPa, reported in a previous study are considered. Existing stress-strain models are investigated and fit to the AHSS database, in addition to the development of new material models. The required input parameters of the proposed stress-strain models are determined, and their corresponding predictive expressions are proposed. It is shown the stress-strain behaviors of AHSS could be accurately described by the proposed models. The data generated by this research addresses fire safety design and will be essential in supporting the adoption of these next-generation steels in future infrastructure.

Mechanical behaviour of TRC thin-plates exposed to high temperature: experimental study

Textile reinforced concrete (TRC) is a type of composite material with great potential in lightweight and thin-walled structural components bearing high capacity. In this study, TRC thin-plates with epoxy resin impregnated fibre (type 1) and non-impregnated fibre (type 2) were exposed to high temperatures from 35°C to 800°C with the unstressed residual test method. The processed TRC thin-plates were examined through four-point bending tests with the aim of building a foundation for a fire prevention code for TRC. The results demonstrate that the ultimate load of type 1 TRC thin-plates is relatively high and does not vary significantly when the target temperature is below 200°C. The ultimate load of type 2 TRC thin-plates is lower than that of type 1, and does not vary significantly when the target temperature is below 400°C; the turning point for the reduction of ultimate load is 400–500°C, and 20% of loading capacity at normal temperature is maintained at 800°C. Stripping damage to type 1 occurs along the interface and the damage is brittle. For a target temperature of 300°C, epoxy resin is prone to deteriorate and the bursting ratio of the specimens was 100%. The damage feature of type 2 thin-plates is a slipping failure between fibre and mortar mixes, and significant ductile damage properties were observed during the damage process. The investigations were also accompanied by scanning electron microscope and alpha ray spectrometer analyses, which provided an additional basis for analysing the damaged sections of specimens. The results show that the surface flaws of the carbon filaments, matrix decomposition and the weak bond behaviour between the fibres and matrix are affected by elevated temperatures. These three factors may result in the decline of the bearing capacity of type 2 TRC thin-plates.

A Novel Robust Tracking Algorithm in Cluttered Environments for Distributed Sensor Network

Tracking has attracted much attention over the past few years, particularly in the field of distributed sensor network. The most challenging issue is nonline of sight (NLOS) problem in cluttered environments such as indoor or urban areas since the presence of NLOS errors leads to severe degradation in the tracking performance. In this paper, we propose a novel robust tracking algorithm to mitigate the measurement noise and NLOS error. The robust localization method is firstly employed to estimate the positions of the mobile node with different subgroups. Then the residual test method is used to remove the larger localization error. Finally, the modified Kalman filter is introduced to improve the tracking accuracy. Simulation results show that the proposed algorithm can track the mobile node and estimate the position with relatively higher accuracy in comparison with existing methods.