Suchergebnisse

"In missing data analysis, there is often a need to assess the sensitivity of key inferences to departures from untestable assumptions regarding the missing data process. Such sensitivity analysis often requires specifying a missing data model which commonly assumes parametric functional forms for the predictors of missingness. In this paper, we relax the parametric assumption and investigate the use of a generalized additive missing data model. We also consider the possibility of a non-linear relationship between missingness and the potentially missing outcome, whereas the existing literature commonly assumes a more restricted linear relationship. To avoid the computational complexity, we adopt an index approach for local sensitivity. We derive explicit formulas for the resulting semiparametric sensitivity index. The computation of the index is simple and completely avoids the need to repeatedly fit the semiparametric nonignorable model. Only estimates from the standard software analysis are required with a moderate amount of additional computation. Thus, the semiparametric index provides a fast and robust method to adjust the standard estimates for nonignorable missingness. An extensive simulation study is conducted to evaluate the effects of misspecifying the missing data model and to compare the performance of the proposed approach with the commonly used parametric approaches. The simulation study shows that the proposed method helps reduce bias that might arise from the misspecification of the functional forms of predictors in the missing data model. We illustrate the method in a Wage Offer dataset"--National Bureau of Economic Research web site

Blockchain technology is suited to the high-quality development of the digital economy in addressing privacy and data security issues. This study explores the synergistic mechanism of the following six factors from three dimensions based on the Technology-Organization-Environment (TOE) framework theory with a fuzzy set qualitative comparative analysis (fs/QCA) method: technology, organization, and environment, namely, Blockchain service capability, Blockchain knowledge accumulation, government attention allocation, government funding support, industry carrying capacity and blockchain technology R&D environment, on the quality of the digital economy of 43 cities in China. The conclusions are as follows: (1) the absence of government funding regarding the blockchain domain is a condition contributing to the absence of high urban digital economy quality; (2) there are three driving configurations for the high-quality urban digital economy in the blockchain technology adoption perspective, which are as follows: knowledge-industry driven, government-service driven, and R&D-service driven; (3) there is one driving configuration for the absence of high urban digital economy quality, namely the knowledge-R&D-funding-inhibiting type. The relevant policy implications can provide theoretical references for local governments to develop the digital economy with the help of blockchain technology.

Climatic Challenges and the Conservation Action Levels -- Evaluation and Management Approaches -- Regional Protection and Risk Management for the Coastal Heritage Sites in Syria -- Microclimate Field Survey in Arwad Island, Syria -- Microclimate Field Survey in the old city of Tartous, Syria -- Zoom Out- Zoom In Conservation Strategies and Intervention Levels

Urban expressways can generate excessive noise in the surrounding urban areas, and it tends to be more complex in mountainous cities, due to the undulating terrain, dense population and compact urban structures. This article aims to investigate the objective acoustic environment and road traffic noise exposure, including the noisy evaluation, annoyance and effect of roadside apartments in residential areas close to urban expressways in the high-density, high-rise, mountainous city of Chongqing. Three housing estates were selected for a series of field measurements, questionnaire surveys and noise mapping. There was a significant negative correlation between night-time noise levels and the distances to the urban expressway ( p <  0.01). Moreover, the differences between the daytime and night-time noise levels were generally insignificant (0.7 to 3.6 dBA) at the roadside locations. Differences in reaction to noise exposure in a variety of both person-related and housing condition variables were found, especially between roadside and non-roadside locations or residents. In addition, 75.0% of roadside residents identified the traffic noise as 'very' or 'extremely' annoying, and 66.7% of them regarded the acoustic environment as the priority environmental factor that needs to be improved. Difference in the 'bedroom-window orientation' had a significant effect on subjective noise evaluation. Rectangular-shaped apartments along the roadside obtain better noise reduction capacities than tower-blocks through the simulation. The acoustic performance of road cuttings, as an appropriately designed earth embankment, is improved along with deeper vertical alignment, and slope angles of 30° and 75° should be avoided.

Public safety and health cannot be secured without the comprehensive recognition of characteristics and reliable emergency response schemes under the disaster chain. Distinct from emergency resource allocation that focuses primarily on a single disaster, dynamic response, periodic supply, and assisted decision-making are necessary. Therefore, we propose a multiobjective emergency resource allocation model considering uncertainty under the natural disaster chain. Resource allocation was creatively combined with path planning through the proposed multiobjective cellular genetic algorithm (MOCGA) and the improved A* algorithm with avoidance of unexpected road elements. Furthermore, timeliness, efficiency, and fairness in actual rescue were optimized by MOCGA. The visualization of emergency trips and intelligent avoidance of risk areas were achieved by the improved A* algorithm. The effects of logistics performance, coupling of disaster factors, and government regulation on emergency resource allocation were discussed based on different disaster chain scenarios. The results show that disruption in infrastructure support, cascading effect of disasters, and time urgency are additional environmental challenges. The proposed model and algorithm work in obtaining the optimal solution for potential regional coordination and resilient supply, with a 22.2% increase in the total supply rate. Cooperative allocation complemented by political regulation can be a positive action for successfully responding to disaster chains.