Yahui Zhang, Aimin Li, Haopeng Li, Fei Chen and Ruiying Shen
A tightly coupled global navigation satellite system (GNSS)-Vision-IMU-wheel odometer (GVIWO) system is proposed, which can realize robust positioning in extreme environments. The…
Abstract
Purpose
A tightly coupled global navigation satellite system (GNSS)-Vision-IMU-wheel odometer (GVIWO) system is proposed, which can realize robust positioning in extreme environments. The purpose of this study is to achieve adaptive initialization in complex environments, sensor anomaly detection and processing, and adaptive robust localization in extreme environments.
Design/methodology/approach
Adaptive initialization includes traditional dynamic and static initialization and extreme condition initialization. To deal with the unstable visual features in the state of excited motion, a method of wheel odometer assisted initialization is designed. According to the abnormal condition of the sensor, the anomaly detection and attenuation mechanism are designed to realize the accurate positioning of the sensor under abnormal condition.
Findings
Tight coupling optimization of GNSS signals, RGB+Depth Map cameras, inertial measurement units and wheel odometers ensures accurate positioning in both indoor and outdoor environments. Through open data sets and field validation experiments, the proposed tightly coupled system has strong adaptability, especially in extreme environments.
Originality/value
A new framework is proposed by integrating GNSS, visual, inertial measurement unit (IMU) and wheel odometer sensors to form an efficient positioning solution. An adaptive initialization method is proposed to enhance the robustness and real-time performance of the positioning system in complex and dynamic environments. A mechanism for detecting and attenuating sensor anomalies is designed, enabling quasideterministic positioning under sensor anomalies.
Details
Keywords
In recent years, we have witnessed a surge in academic interest towards migrants and their entrepreneurial endeavours. This has resulted in valuable insights about immigrant…
Abstract
In recent years, we have witnessed a surge in academic interest towards migrants and their entrepreneurial endeavours. This has resulted in valuable insights about immigrant, transnational, ethnic and diaspora entrepreneurship. By reviewing 158 articles published in the fields of migrant entrepreneurship, transnational entrepreneurship, ethnic and diaspora entrepreneurship over the last decade, the author maps the migrant entrepreneurship field according to the level of analysis and suggests potential avenues for the development of the field. Blurred boundaries between different streams of literature can potentially lead to duplication of efforts and harm cumulativity of knowledge. Therefore, the author summarises the key findings at each level of analysis, identifies the gaps and most pressing research questions. The author concluded that the field would benefit from (1) more specific definitions and assessment of whether observed findings stem from immigrant-, transnational-, ethnic- or diaspora-related factors; (2) appreciating the multilevel nature of the phenomenon; and (3) clarifying the boundary conditions. This review contributes to the accumulation of knowledge in two ways. First, it synthesises the findings in the fields of transnational, immigrant, ethnic and diaspora entrepreneurship under the framework of migrant entrepreneurship. Second, it suggests potential research directions across three levels of analysis and in-between those levels.
Details
Keywords
Jin Tang, Weijiang Li, Jiayi Fang, Zhonghao Zhang, Shiqiang Du, Yanjuan Wu and Jiahong Wen
Quantitative and spatial-explicit flood risk information is of great importance for strengthening climate change adaptation and flood resilience. Shanghai is a coastal megacity at…
Abstract
Purpose
Quantitative and spatial-explicit flood risk information is of great importance for strengthening climate change adaptation and flood resilience. Shanghai is a coastal megacity at large estuary delta with rising flood risks. This study aims to quantify the overall economic-societal risks of storm flooding and their spatial patterns in Shanghai.
Design/methodology/approach
Based on multiple storm flood scenarios at different return periods, as well as fine-scale data sets including gridded GDP, gridded population and vector land-use, a probabilistic risk model incorporating geographic information system is used to assess the economic-societal risks of flooding and their spatial distributions.
Findings
Our results show that, from 1/200 to 1/5,000-year floods, the exposed assets will increase from USD 85.4bn to USD 657.6bn, and the direct economic losses will increase from USD 3.06bn to USD 52bn. The expected annual damage (EAD) of assets is around USD 84.36m. Hotpots of EAD are mainly distributed in the city center, the depressions along the upper Huangpu River in the southwest, the north coast of Hangzhou Bay, and the confluence of the Huangpu River and Yangtze River in the northeast. From 1/200 to 1/5,000-year floods, the exposed population will rise from 280 thousand to 2,420 thousand, and the estimated casualties will rise from 299 to 1,045. The expected annual casualties (EAC) are around 2.28. Hotspots of casualties are generally consistent with those of EAD.
Originality/value
In contrast to previous studies that focus on a single flood scenario or a particular type of flood exposure/risk in Shanghai, the findings contribute to an understanding of overall flood risks and their spatial patterns, which have significant implications for cost-benefit analysis of flood resilience strategies.
Details
Keywords
J. Yin, R. Hales, P. Pilidis, B. Curnock and R. Meads
A two‐dimensional high‐bypass ratio turbofan performance model was developed in order to predict accurately gas turbine transient performance. In the present model, the fan of…
Abstract
A two‐dimensional high‐bypass ratio turbofan performance model was developed in order to predict accurately gas turbine transient performance. In the present model, the fan of high bypass engines has strong radial profiles of all thermodynamic variables. It is common to average these profiles so that the fan can be represented by one or two one‐dimensional characteristics. The present paper describes how the radial profiles can be used to make an estimation of turbofan transient performance. The results are somewhat different to those produced using two one‐dimensional compressor performance maps.
Details
Keywords
Shaodi Zhao, Yan Yin, Jiusheng Bao, Xingming Xiao, Zengsong Li and Guoan Chen
The friction between brake pair causes an intense temperature rise on interface during braking, which affects the braking performance seriously. Therefore, building an accurate…
Abstract
Purpose
The friction between brake pair causes an intense temperature rise on interface during braking, which affects the braking performance seriously. Therefore, building an accurate testing method for frictional temperature rise (FTR) is a prerequisite.
Design/methodology/approach
Facing braking conditions of automobiles, an experimental system for testing of FTR based on preset thermometry method (PTM) was established. The FTR was collected by the PTM and the variation laws as well as the cause of errors were analyzed by experiments. The deviations between tested and real temperature were corrected based on tribology and heat theories. Finally, an online prediction method for FTR was pointed out.
Findings
After correction, the temperature curve accords well with the laws of tribology and thermal theories. The corrected FTR at braking end point is approximately equal to the authentic temperature test by hand thermometer.
Originality/value
This study eliminated the hysteresis phenomenon of temperature rise sequence and lays a foundation for online accurate monitoring and warning of brake friction temperature rise. It has important theoretical and practical value for expanding the monitoring and improvement of brake performance.
Details
Keywords
Suk-Joong Kim, Linda Lee and Eliza Wu
This chapter investigates the impact of policy interest rate news from the U.S. Federal Reserve (Fed) and the European Central Bank (ECB) on stock returns and volatilities of U.S…
Abstract
This chapter investigates the impact of policy interest rate news from the U.S. Federal Reserve (Fed) and the European Central Bank (ECB) on stock returns and volatilities of U.S. NYSE and German DAX listed commercial banks. We find that Fed news has the most influence on both U.S. and German listed bank stocks and an unexpected policy rate increase (decrease) lowers (raises) returns and raises volatility in the majority of cases. On the other hand, ECB news generally increases bank stock volatility in the United States but has little impact within its own domestic banking industry. While our results for the U.S. listed banks confirm that their stock prices are more responsive in bad economic times and also during periods of monetary tightening, we find disparities for German banks suggesting that U.S. and European banking industries respond heterogeneously to monetary policy news but the Global Financial Crisis increased the sensitivity of all banks to monetary policy news.
Details
Keywords
This chapter develops an asymptotic theory for a general transformation model with a time trend, stationary regressors, and unit root nonstationary regressors. This model extends…
Abstract
This chapter develops an asymptotic theory for a general transformation model with a time trend, stationary regressors, and unit root nonstationary regressors. This model extends that of Han (1987) to incorporate time trend and nonstationary regressors. When the transformation is specified as an identity function, the model reduces to the conventional cointegrating regression, possibly with a time trend and other stationary regressors, which has been studied in Phillips and Durlauf (1986) and Park and Phillips (1988, 1989). The limiting distributions of the extremum estimator of the transformation parameter and the plug-in estimators of other model parameters are found to critically depend upon the transformation function and the order of the time trend. Simulations demonstrate that the estimators perform well in finite samples.
Details
Keywords
Jörn Obermann and Patrick Velte
This systematic literature review analyses the determinants and consequences of executive compensation-related shareholder activism and say-on-pay (SOP) votes. The review covers…
Abstract
This systematic literature review analyses the determinants and consequences of executive compensation-related shareholder activism and say-on-pay (SOP) votes. The review covers 71 empirical articles published between January 1995 and September 2017. The studies are reviewed within an empirical research framework that separates the reasons for shareholder activism and SOP voting dissent as input factor on the one hand and the consequences of shareholder pressure as output factor on the other. This procedure identifies the five most important groups of factors in the literature: the level and structure of executive compensation, firm characteristics, corporate governance mechanisms, shareholder structure and stakeholders. Of these, executive compensation and firm characteristics are the most frequently examined. Further examination reveals that the key assumptions of neoclassical principal agent theory for both managers and shareholders are not always consistent with recent empirical evidence. First, behavioral aspects (such as the perception of fairness) influence compensation activism and SOP votes. Second, non-financial interests significantly moderate shareholder activism. Insofar, we recommend integrating behavioral and non-financial aspects into the existing research. The implications are analyzed, and new directions for further research are discussed by proposing 19 different research questions.