scholarly journals Ground Risk Assessment of UAV Operations Based on Horizontal Distance Estimation under Uncertain Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yang Liu ◽  
Xuejun Zhang ◽  
Zhi Wang ◽  
Ziang Gao ◽  
Chang Liu
Keyword(s):  
Drag Force ◽  
Safety Assessment ◽  
Local Population ◽  
Assessment Model ◽  
Flying Height ◽  
Weather Data ◽  
Horizontal Distance ◽  
Proposed Model ◽  
Failure Point ◽  
The Impact

In this paper a ground safety assessment model is introduced based on the probability estimation of possible impact positions when unmanned aerial vehicle (UAV) crashes on the ground. By incorporating the random uncertainties during the descending process, risks associated with UAV’s ground crash are estimated accurately. The number of victims on the ground per flight hour is selected as the indicative index to evaluate the risk levels of the corresponding ground area. We mainly focus on the analysis of uncertainties that usually appear in drag coefficient which would generate a great amount of effects on the travelled horizontal distance from the failure point to the impact point on the ground, which further influences the possible impact positions. The drag force in the air, failure velocity of a UAV, and wind effects in the local area are all considered in the proposed model, as well as ground features, including sheltering effects on the ground, UAV parameter settings, and distribution of local population. Uncertainties in drag force when a UAV descends, UAV’s initial horizontal and vertical speeds at failure point, and local wind patterns are all considered as the indispensable factors in the proposed model. Especially the probability of fatality once hit by the UAV’s debris is explored to make the safety assessment more reliable and valuable. In the end, the actual UAV parameters and official historical weather data are used to estimate the risks in a real operation environment when a failure event happens at a legal flying height. Experimental results are given based on different types of UAVs and random effects in the descent. The results show that all the operations of all kinds of UAVs selected in the validation are so dangerous that the safety of people on the ground cannot be guaranteed, whose value is much bigger than the manned aircraft safety criterion 10−7.

scholarly journals Evaluating the Safety Impact of Connected and Autonomous Vehicles with Lane Management on Freeway Crash Hotspots Using the Surrogate Safety Assessment Model

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Hui Zhang ◽  
Ninghao Hou ◽  
Jianhua Zhang ◽  
Xuyi Li ◽  
Yan Huang
Keyword(s):  
Traffic Safety ◽  
Autonomous Vehicles ◽  
Safety Assessment ◽  
Assessment Model ◽  
Trajectory Data ◽  
Collision Risk ◽  
Velocity Difference ◽  
Safety Benefit ◽  
Crash Hotspots ◽  
The Impact

One goal for large-scale deployment of connected and autonomous vehicles is to achieve the traffic safety benefit since connected and autonomous vehicles (CAVs) could reduce the collision risk by enhancing the driver’s situation perception ability. Previous studies have analyzed the safety impact of CAVs involved in traffic, but only few studies examined the safety benefits brought by CAVs when approaching high-collision-risk road segments such as the freeway crash hotspots. This study chooses one freeway crash hotspot in Wuhan, China, as an instance and attempts to estimate the safety benefits for differential penetration rates (PRs) of CAVs using the surrogate safety assessment model (SSAM). First, the freeway crash hotspot is identified with kernel density estimation and simulated by VISSIM. Then, the intelligent driver model (IDM) and Wiedemann 99 (a car-following model) are adopted and calibrated to control the driving behaviors of CAVs and human-driven vehicles (HVs) in this study, respectively. The impact that rather CAVs are constrained with or without managed lanes on traffic safety is also discussed, and the PR of CAVs is set from 10% to 90%. The results of this study show that when the PR of CAVs is lower than 50%, there is no significant improvement on the safety measures such as conflicts, acceleration, and velocity difference, which are extracted from the vehicle trajectory data using SSAM. When the penetration rate is over 70%, the experiment results demonstrate that the traffic flow passing the freeway hotspot is with fewer conflicts, smaller acceleration, and smaller velocity difference in the scenario where CAVs are constrained with managed lane compared with the scenario without managed lane control. The safety benefit that CAVs bring needs to be discussed. The lane management of CAVs will also lead to distinct safety impact.

scholarly journals A Security Assessment Model for Electrical Power Grid SCADA System

2019 ◽  
Vol 8 (12S2) ◽  
pp. 763-773
Keyword(s):  
Vulnerability Assessment ◽  
Cyber Security ◽  
Large Scale ◽  
Critical Infrastructure ◽  
Security Analysis ◽  
Assessment Model ◽  
Primary Concern ◽  
Scada System ◽  
Proposed Model ◽  
The Impact

Due to the wide application of SCADA systems in national critical infrastructure, their cyber security issues and vulnerabilities have been a primary concern; whereas, the impact and consequences of cyber-attacks to these systems have the potential to result in catastrophic consequences in the physical domain. Therefore, estimating possible attack impacts and identifying system vulnerabilities are major concern in SCADA management and operations. However, it is quite difficult to plan, execute and review vulnerability analysis in critical infrastructure systems as well as in industrial control systems (such as SCADA system) due to its complexity, large-scale and heterogeneity. Consequently, a consistent domain-specific conceptual model is required to establish a generic framework for cyber security analysis to examine and investigate security threats on cyber-physical systems, the role of the entities within the system as well as system operations. The main contribution of this work is to present a multi-facets model to support cyber security analysis practices such as penetration testing, vulnerability assessment and risk analysis. The proposed model presents a common insight among different SCADA configurations, implementations and the employed protocols to handle its complexity, heterogeneous and scale. To demonstrate the usability as a proof of concept and applicability of the proposed model, the paper also presents an example illustrating how the proposed model can be employed to carry out security vulnerability assessment.

Computing the Minimal U-Turn Offset for an Unsignalized Superstreet

2017 ◽  
Vol 2618 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Liu Xu ◽  
Xianfeng Yang ◽  
Gang-Len Chang
Keyword(s):  
Safety Assessment ◽  
Critical Role ◽  
Geometric Design ◽  
Safety Performance ◽  
Assessment Model ◽  
Traffic Dynamics ◽  
Convenient Tool ◽  
Proposed Model ◽  
Different Levels

Despite the extensive implementations of unsignalized superstreets in practice, reliable methodologies for their geometric design remain unavailable. In recognition of the critical role of the U-turn offset length design, this study proposed an applicable tool to help traffic professionals determine the minimum required offset length for safety needs. The proposed model offers a convenient tool to evaluate a candidate design on the basis of traffic dynamics and driver gap acceptance behavior. In addition, this model can be used to assess whether installation of signals is needed to accommodate growing traffic. With the use of the surrogate safety assessment model as an unbiased tool, this study evaluated the safety performance of one superstreet with varied U-turn offset lengths (i.e., 700, 1,100, and 1,500 ft). Comparisons of the results of different designs indicated that the safety performance of the superstreet would not be compromised if the U-turn offset was reduced from 1,500 to 1,100 ft. However, more severe crashes were observed when the U-turn offset length was 700 ft. Further extensive analyses on different levels of demand also confirmed the need to properly design the offset length in an unsignalized superstreet.

scholarly journals Assessment of Quality in Saudi Arabian Roadways

2021 ◽  
pp. 209-219
Author(s):  
Muwaffaq Alqurashi
Keyword(s):  
Fuzzy Logic ◽  
Field Survey ◽  
Saudi Arabian ◽  
Fuzzy Logic System ◽  
Assessment Model ◽  
Approximate Reasoning ◽  
Proposed Model ◽  
Study Results ◽  
The Impact ◽  
Logic System

A new assessment model was developed in this work. The developed model introduced a new approach and reference for assessment factors control the quality in Saudi Arabian roads using the fuzzy logic system. Fuzzy logic system was chosen to be used in this research due to its suitability for uncertain and approximate reasoning that involves human intuitive thinking as well as, it requires a little data to achieve the aim of the proposed model. Furthermore, the fuzzy logic has the ability for combining many effects such as the probability of occurrence and the impact of factors on the quality of roadways construction. The methodology of this research included conducting a field survey with construction practitioners in the field of roadways projects across Saudi Arabia. The proposed model was then evaluated and applied using the collected data from the field survey. The study results proved that the proposed model can be successfully used in the assessment of factors affecting quality in roadways. The major factors that found to be significantly affecting the quality in construction of roadways projects were identified according to their importance as; 1) Change order control; 2) Fluctuation default of Subcontractor; 3) Third party delay 4) Contract dispute results from disagreement. The proposed model is considered as a general model that can be easily adapted and applied to other types of projects.

scholarly journals Random Parameters and Sources of Uncertainty in Practical Fire Safety Assessment of Steel Building Structures

2016 ◽  
Author(s):  
Pawel Artur Król
Keyword(s):  
Fire Safety ◽  
Safety Assessment ◽  
Elevated Temperatures ◽  
Probabilistic Approach ◽  
Steel Structures ◽  
Building Structures ◽  
Sources Of Uncertainty ◽  
Proposed Model ◽  
Structural Resistance ◽  
The Impact

The purpose of this article is to identify sources of uncertaintyand outline the basis of probabilistic safety assessmentof steel structures exposed to fire conditions. Awareness of theexistence of unavoidable uncertainties and non-deterministicnature of many phenomena and parameters may be essentialfor a proper understanding of the issues of structural reliabilityin the event of extreme or accidental actions.The study highlights various sources of uncertainty associatedwith practical fire safety assessment of steel structureswhich significantly affects the reliability of estimates. Universalfactors influencing random structural resistance in alldesign conditions were separately described. A significant partof the paper is devoted to issues that relate only to an accidentaldesign situation of fire. Reference was made to the uncertaintyof the analytical model describing the bearing capacityof the structure in terms of probabilistic approach. A syntheticsummary on the impact of the method of carrying out materialtesting in elevated temperatures on the strength parameters,was made. In the conclusion it has been underlined that, interalia, due to the lack of relevant statistical data, conducting afully reliable probabilistic analysis of random structural resistanceunder fire is currently not possible. A unique part of thepaper contains the proposed model of probability-based analyticalapproach to assess random structural resistance in fireconditions, incorporating an authorial modification to modelsused for standard conditions.

scholarly journals Conditional Love: Threat and Attitudinal Perceptions of Immigrants Depend on Their Instrumentality to Locals’ Basic Psychological Needs

2021 ◽  
pp. 014616722098464
Author(s):  
Jose C. Yong ◽  
Lile Jia ◽  
Ismaharif Ismail ◽  
Peiwei Lee
Keyword(s):  
Local Population ◽  
Self Determination Theory ◽  
Psychological Needs ◽  
Basic Psychological Needs ◽  
Attitudes Toward Immigrants ◽  
Threat Perceptions ◽  
Proposed Model ◽  
Perceived Instrumentality ◽  
Intergroup Conflicts ◽  
The Impact

Although threat perceptions are commonly used to explain attitudes toward immigrants, the psychological factors underlying threat are surprisingly understudied. Drawing from goal pursuit and self-determination theory, we examined the perceived instrumentality of immigrants as an antecedent of locals’ threat and attitudinal perceptions. Through four studies ( N = 1,372) with different configurations of local population segments and target immigrant groups, we investigated the impact of immigrants’ instrumentality in terms of hindrances to locals’ autonomy, belonging, and competence needs. Including hindrances to our proposed model of threats and attitudes led to an improvement in the overall fit with the data, allowed for a better specification of the threats-to-attitudes pathways, and elucidated the complexity and downstream consequences (endorsement of pro-immigration policies) of attitudes. The present findings underscore the utility of goal-driven approaches to studying intergroup conflicts, and implications for understanding and improving locals’ attitudes toward immigrants are discussed.

Test of Mediation and Moderation between Employee Empathy and Customers’ Advocacy

2020 ◽  
Author(s):  
Sajjad Ahmad Afridi ◽  
Asad Shahjehan ◽  
Maqsood Haider ◽  
Dr Uzma Munawar
Keyword(s):  
Factor Analysis ◽  
Customer Loyalty ◽  
Service Sector ◽  
Mediating Effect ◽  
First Line ◽  
Private Hospitals ◽  
Proposed Model ◽  
Confirmatory Factor ◽  
The Impact ◽  
Significant Moderator

This study examined the impact of employee empathy on customers’ advocacy directly and indirectly through customers’ loyalty. Moreover, the interacting effect of customers’ trust was verified between the association of customers’ loyalty and advocacy. The attributes of the proposed model were examined in the context of first line employee and patients’ interactions. A total of 220 responses were collected for analysis from the private hospitals of Peshawar. The model fitness was confirmed through confirmatory factor analysis and hypotheses were examined. Findings confirmed the positive and significant impact of employee empathy on customers’ advocacy. Further, the mediating effect was examined and found that loyalty partially mediates employee empathy and customers’ advocacy. Additionally, trust was found a significant moderator between the association of customer loyalty and advocacy. Furthermore, findings revealed that trust based loyalty significantly and positively mediates employee empathy and customers’ advocacy. Findings of the present study provide understanding for the service sector, particularly in healthcare, to enhance customers’ loyalty, advocacy, and trust through service employee’s empathic aptitude. Keywords: Employee empathy, Service Eco-system, Customers’ Loyalty, Customers’ Advocacy, Trust-Based Loyalty, Healthcare, S-D Logic

Key Aspects of Assessing Effectiveness and Efficiency of Implementation of the Federal Clean Air Project on the Example of the Comprehensive Emission Reduction Action Plan in Nizhny Tagil

2020 ◽  
pp. 48-60
Author(s):  
SV Yarushin ◽  
DV Kuzmin ◽  
AA Shevchik ◽  
TM Tsepilova ◽  
VB Gurvich ◽  
...  
Keyword(s):  
Emission Reduction ◽  
Action Plan ◽  
Local Population ◽  
Ambient Air ◽  
Ambient Air Pollution ◽  
Mortality And Morbidity ◽  
Industrial Enterprises ◽  
Clean Air ◽  
Effectiveness And Efficiency ◽  
The Impact

Introduction: Key issues of assessing effectiveness and economic efficiency of implementing the Federal Clean Air Project by public health criteria are considered based on the example of the Comprehensive Emission Reduction Action Plan realized in the city of Nizhny Tagil, Sverdlovsk Region. Materials and methods: We elaborated method approaches and reviewed practical aspects of evaluating measures taken in 2018–2019 at key urban industrial enterprises accounting for 95 % of stationary source emissions. Results: Summary calculations of ambient air pollution and carcinogenic and non-carcinogenic inhalation health risks including residual risks, evaluation of the impact of air quality on urban mortality and morbidity rates, economic assessment of prevented morbidity and premature mortality cases have enabled us not only to estimate health effects but also to develop guidelines for development and implementation of actions aimed at enhancing effectiveness and efficiency of industrial emission reduction in terms of health promotion of the local population. Conclusions: We substantiate proposals for the necessity and sufficiency of taking remedial actions ensuring achievement of acceptable health risk levels as targets of the Comprehensive Emission Reduction Action Plan in Nizhny Tagil until 2024 and beyond.

Higher-Order Thinking Skills (HOTS)-based Formative Assessment: A Proposed Model for Language Learning Assessment

2020 ◽  
Vol 9 (2) ◽  
pp. 115
Author(s):  
Wiyaka Wiyaka ◽  
Entika Fani Prastikawati ◽  
AB Prabowo Kusumo Adi
Keyword(s):  
Formative Assessment ◽  
Language Learning ◽  
Higher Order Thinking ◽  
Thinking Skills ◽  
Higher Order ◽  
Formative Assessments ◽  
Assessment Model ◽  
Higher Order Thinking Skills ◽  
Learning Assessments ◽  
Proposed Model

<div><p class="StyleABSTRAKenCambria">The integration of higher-order thinking skills (HOTS) in language learning assessments has become a crucial issue in 21st-century learning. However, not many teachers are aware of the need to incorporate HOTS in assessments due to their insufficient knowledge and the absence of good examples. Further, there is not much research and literature on HOTS-based formative assessment that can be used as references. This research aims to fill the existing gap by providing a model of higher-order thinking skills (HOTS)-based formative assessments for English learning, especially in junior high schools. By employing research and development design, this research describes the validation of the assessment model. The proposed model of assessment may be used as a prototype for assessing language learning.</p></div><p> </p>

The impact of duration observations on precision of results GNSS measurements

2017 ◽  
Vol 921 (3) ◽  
pp. 7-13 ◽  
Author(s):  
S.V. Grishko
Keyword(s):  
Measurement Accuracy ◽  
Functional Dependence ◽  
Observation Time ◽  
Satellite Networks ◽  
Satellite Measurements ◽  
Proposed Model ◽  
Actual Error ◽  
Gnss Measurements ◽  
The Impact ◽  
Qualitative Characteristics

This paper shows that the accuracy of relative satellite measurements depend not only on the length of the baseline, as it is regulated by the rating formula of accuracy of GNSS equipment, but also on the duration of observations. As a result of the strict adjustment much redundant satellite networks with different duration of observations obtained covariance matrix of baselines, the most realistic reflecting the actual error of satellite observations. Research of forms of communication of these errors from length of the baseline and duration of its measurement is executed. A significant influence of solar activity on accuracy of satellite measurements, in general, leads to unequal similar series of measurements made at different periods, for example, in the production of monitoring activities. The model of approximation of the functional dependence of accuracy of the baseline from its length and duration of observations having good qualitative characteristics is offered. Based on the proposed model, we analyzed the dynamics of changes in measurement accuracy with an increase in observation time.

Sign in / Sign up

Export Citation Format

Share Document