Minimum Safe Distance Research Articles

Conductor minimum safe distance analysis: Application of a 20 kV medium voltage airline (SUTM) system

Medium Voltage Air Line Conductor (SUTM) has a voltage of 20 kV. The SUTM network should have the criteria for electricity safety techniques, including minimum safety distances between the trees and the environment and the effectiveness of electricity distribution development. There are ten stages in the installation of the new SUTM 20 kV network. The results of the study concluded that the Conductor used in the planning of the 20 kV SUTM new network construction was AAACS - 150 mm2. The safe distance between the conductors and the conditions contained Billboards are 0.5 meters with a minimum height difference of ± 2.5 meters. Whereas the safe distance between the conductor and the tree is ± 0.5 meters, but the Medium Voltage Network Construction Standard for Electric Power must have a height difference of 2.5 meters. The distance between the conductor and billboards is 0.5 meters, which does not complete the standard instructions.

Damage mode and dynamic response of RC girder bridge under explosions

During the whole service life, bridge structures potentially suffered from the threats from military conflicts, terrorist attacks and accidental explosions. The related studies on the damage modes and dynamic responses of entire RC girder bridges subjected to the explosion loadings is very limited, which is addressed through high-reliability numerical simulations. Firstly, by comparing with the experimental overpressure- and acceleration-time histories, as well as the damage modes from the explosion tests on 1/5 scaled two-span girder bridges, the validities of the material models and corresponding parameters, as well as the numerical simulation algorithms are verified sufficiently. Then, three levels of potential explosive threats, i.e., suitcase, sedan, and small moving van (the corresponding equivalent cubic TNT explosive masses are 23 kg, 454 kg and 4536 kg) specified by Federal Emergency Management Agency (FEMA) were selected to analyze the damage modes and dynamic responses of a typical four-span prototype RC girder bridge under both below- and above-deck explosion scenarios. Furthermore, the blast resistance of both simply-supported and continuous girder bridges were examined, and the minimum safe distances were proposed. It derives that, (i) for the below-deck explosion scenarios, total nine damage modes exist from small-scale spalling of concrete at the bottom of pier to the total collapse of the bridge; (ii) for the above-deck explosion scenarios, eight damage modes can be induced, including cratering and opening in deck, flexural failure of the T-girder, etc.; (iii) the continuous bridge exhibits obvious and slight enhanced blast resistance for below- and above-deck explosions than simply-supported girder bridges; (iv) small moving van can lead to the destruction of the entire bridge, the minimum safe standoff distances for suitcase and sedan bombs are 0.5 m and 3.0 m.

АЛГОРИТМ МАНЕВРИРОВАНИЯ АВТОНОМНОГО НЕОБИТАЕМОГО ПОДВОДНОГО АППАРАТА ПРИ ПРОВОДКЕ СУДНА ЧЕРЕЗ ЗАМИНИРОВАННЫЙ РАЙОН

One of the tasks assigned to the autonomous underwater vehicles (AUV) is the fightagainst mine danger, which includes: 1) search for and destroy mines in the mined area;2) ensure their own safety when passing through the mined area or when working in this area;3) ensure the navigation of ships (including submarines) through the mined area. AUV can beconsidered as a further development of mine-fighting equipment, since they have a number ofadvantages over mine-fighting ships: 1) exclude the loss of life in the event of a mine explosion;2) have a lower level of physical fields to which the fuses of sea mines react; 3) are able to maneuverat the optimal depth for searching and classifying mines. In view of this, the creation ofspecialized AUV to combat the mine danger is very important. The search for mines with thehelp of AUV can be carried out either in the interests of their destruction (clearing the area) orfor the purpose of guiding ships through the mined area. This article deals with the secondproblem. The description of the maneuvering algorithm of the AUV when ensuring the passageof a vessel through a mined area is given. The task is solved by detecting different types ofmines using hydroacoustic and magnetometric means of searching and classifying underwaterobjects and bypassing of the mines at a safe distance. To reduce the time required to solve thetask, the detected underwater objects are classified into the "mine-like object" and "other objects"classes. The use of the "mine-like object" class, which includes both the actual mines andobjects that are indistinguishable from mines at the distances of their detection by means ofmine search, allows you to avoid approaching detected underwater objects at a distance of theirconfident classification using high-frequency sonar and television equipment, and thereby increasethe safety of the AUV and reduce the time of passage through the mined area. The algorithmtakes into account the fact that the minimum safe distance between vessel and mine greatlyexceeds the range of detection of mines of different types that does not allow AUV to find asafe vessel passage through the mined area by a single crossing and requires complex maneuveringof the AUV. Algorithm is intended for implementation in the AUV control system.

Modeling and Analysis on Minimum Safe Distance for Platooning Vehicles Based on Field Test of Communication Delay

Vehicle platooning is a perspective technique for intelligent transportation systems (ITS). Connected and automated vehicles (CAVs) use dedicated short-range communication (DSRC) to form a convoy, in which the following vehicles can receive the information from their preceding vehicles to achieve safe automated driving and maintain a short headway. Consequently, a vehicle platoon can improve traffic safety and efficiency, further reducing fuel consumption. However, emergency braking inevitably occurs when the platoon meets an accident or a sudden mechanical failure. It is more critical when the wireless communication got delays. Therefore, “how to predefine a minimum safe distance (MSD) considering communication delay” is a challenging issue. To this end, a series of field tests were carried out to measure the communication delay of IEEE 802.11p that is the underlying protocol of DSRC. Subsequently, MSD is modeled and analyzed when the platoon travels at accelerating, cruising, and decelerating states. More importantly, the results of field tests are applied in the models to investigate the impact of communication delay on MSD in practice. The simulation results verify that the proposed model can effectively maintain the platooning vehicles’ safety even if emergency braking happens with certain communication delays.

Predictive Wireless Based Status Update for Communication-Agnostic Sampling

In a wireless network that conveys status updates from sources (i.e., sensors) to destinations, one of the key issues studied by existing literature is how to design an optimal source sampling strategy on account of the communication constraints which are often modeled as queues. In this paper, an alternative perspective is presented—a novel status-aware communication scheme, namely parallel communications , is proposed which allows sensors to be communication-agnostic. Specifically, the proposed scheme can determine, based on an online prediction functionality, whether a status packet is worth transmitting considering both the network condition and status prediction, such that sensors can generate status packets without communication constraints. We evaluate the proposed scheme on a Software-Defined-Radio (SDR) test platform, which is integrated with a collaborative autonomous driving simulator, i.e., Simulation-of-Urban-Mobility (SUMO), to produce realistic vehicle control models and road conditions. The results show that with online status predictions, the channel occupancy is significantly reduced, while guaranteeing low status recovery error. Then the framework is applied to two scenarios: a multi-density platooning scenario, and a flight formation control scenario. Simulation results show that the scheme achieves better performance on the network level, in terms of keeping the minimum safe distance in both vehicle platooning and flight control.

Study the Influence of Distance in Artificial Potential Field (APF) for Autonomous Emergency Braking System (AEB) on Longitudinal Motion

Autonomous Emergency Braking (AEB) is one of the common control systems used by the vehicle in order to avoid the collision from the obstacle. AEB performance optimize mostly on dry road surface at low and medium speed. The slip tire model was derived in this paper in order to find the coefficient of road friction. The tire-road friction coefficient is used for the braking limit which is 450 N.m. In order to increase the ability of an AEB during presence of obstacle in front of the vehicle, combination of Time-to-Collision (TTC) and artificial potential field (APF) are proposed in this study. When the APF value was surpassed the threshold distance, the AEB will activate by itself. The limit for APF was designed based on assuming the dry road friction (0.9) condition and with present of static obstacle in front of the vehicle in longitudinal lane. Thus, the AEB system was designed considering on the dry road friction condition, time for Front Collision Warning (FCW)as well as Braking was included for the limit APF is developed. The combination of an additional distance with the maximum safety distance in the APF system will create the minimum safe distance from obstacle which is in the range of 2.0 meter after the vehicle stop entirely. The additional distance is influence by the product of the constant time setting which is t_s1 and t_s2 with current velocity. Then, the simulation results show that the proposed control strategy can adapt to the dry tire-road friction coefficient on the road.

Secure UAV Random Networks With Minimum Safety Distance

In this correspondence, we study the physical layer security in a stochastic unmanned aerial vehicles (UAVs) network from a network-wide perspective, where the locations of UAVs are modeled as a Mat$\acute{\text{e}}$rn hard-core point process (MHCPP) to characterize the minimum safety distance between UAVs, and the locations of users and eavesdroppers are modeled as a Poisson cluster process and a Poisson point process, respectively. UAVs adopt zero-forcing precoding to serve multiple ground users and emit artificial noise to combat eavesdropping. We derive the approximations for the coverage probability and secrecy probability of a typical user, with which we derive the secrecy throughput of the whole network. Numerical results show the analytical results can well approximate the simulation results. Impacts of parameters on the secrecy performance are shown.

A dynamic cooperative lane-changing model for connected and autonomous vehicles with possible accelerations of a preceding vehicle

The emerging connected and autonomous vehicle (CAV) technologies offer a promising solution to design better lane-changing maneuvers that can reduce the negative impacts of vehicle lane-changing behavior on traffic operations. Existing studies on this topic have predominantly focused on designing lane-changing maneuvers for a subject vehicle (SV) and typically assumed that a vehicle in the target lane must decelerate to make space for the SV due to safety considerations. Nevertheless, jointly designing the trajectories of the SV and surrounding vehicles and allowing possible accelerations of a preceding vehicle may further alleviate the negative impacts of CAV’s lane-changing maneuvers. To investigate this possibility, this paper proposes a dynamic cooperative lane-changing model for CAVs with possible accelerations of a preceding vehicle. This model collects information of the surrounding vehicles and updates the lane-changing decisions for the SV in real time via three steps, namely lane-changing decision making, cooperative trajectory planning, and trajectory tracking. This model applies a linearized vehicle kinematic model to make lane-changing decisions for the SV given the states of the SV and surrounding vehicles, the minimum safety distance, and requirements on the comfort level for passengers. Furthermore, it dynamically designs the longitudinal and lateral trajectories for the SV and surrounding vehicles. Extensive numerical simulation experiments are conducted to evaluate the effectiveness of the proposed model. Results show that the proposed model increases the success rate of the SV’s lane-changing maneuvers, smoothens the trajectories of the SV and vehicles in the upstream direction at the cost of a slightly more significant oscillation of the last vehicle in the downstream direction. Overall, the proposed model reduces the negative impacts of lane-changing maneuvers on the surrounding traffic. The results also reveal the robustness of the model performance by varying several key input parameters in the experiments.

Analysis of Effect Electric Field Strenght on Safe Distance Below Main Substation Busbar 150 kV

This research is to analyze the effect of electric field strength on the safe distance under the 150kV substation busbar. The research was conducted at 150 kV substation Rancaekek, substation Rancakasumba, substation Cikasungka. The electric field exposure threshold value according to SNI, ICNIRP, IRPA/INIRP and WHO is 10kV / m for the working community. The lowest distance of the busbar conductor to the ground surface is 7.5m. Measurements and calculations of transverse electric field strength from busbar 1 to busbar 2. The height of the test point is 0 m to 2.3 m from the ground surface. From the results of the calculation of the electric field, strength obtained that the shortest minimum safe distance is 7.48 m, while the highest minimum safe distance is 7.88 m. From the results of the measurements of the electric field From the results of measurements of electric field strength obtained that the fastest duration of electric field exposure was 4.42 hours while the longest electric field exposure duration was 5.75 hours. From the calculation of the electric field, strength obtained that: the fastest duration of electric field exposure is 7.56 hours while the longest duration of electric field exposure is 7.91 hours.

ANALYSIS OF ON-SITE VIBRATION MONITORING OF STEEL SHEET PILE DRIVING CONSTRUCTION

In this paper, the self-designed system for ground vibration acceleration monitoring was used to monitor the ground vibration caused by steel sheet pile driving in three sites with different soil properties. The peak acceleration and frequency characteristics of ground vibration were analyzed. The vibration attenuation law and the influence on surrounding buildings were discussed. The results show that soil strength has significant influence on the vibration caused by steel sheet pile construction. The penetration rate of steel sheet pile in soil with low resistance is high, causing slight ground vibration response. While in soil with high resistance, the penetration rate is low and the ground vibration is relatively much more obvious. The ground longitudinal and tangential accelerations caused by steel sheet pile construction are close to each other at the same depth, and have a trend to increase with the depth. There is little influence of vibration source distance and soil property on the dominant frequency of ground vibration caused by steel sheet pile construction. A good positive linear correlation shows between the dominant frequency of ground vibration and the vibration frequency of pile construction. The construction vibration of steel sheet pile attenuates rapidly in the range of 4m from the vibration source. The minimum safety distance of steel sheet piles for surrounding buildings due to construction is far smaller than that of soil compaction pile.

Impact of Automated Truck Platooning on the Performance of Freeway Mixed Traffic Flow

Vehicle platooning service through wireless communication and automated driving technology has become a reality. Vehicle platooning means that several vehicles travel like a train on the road with a minimum safety distance, which leads to the enhancement of safety, mobility, and energy savings. This study proposed a framework for exploring traffic mobility and safety performance due to the market penetration rate (MPR) of truck platoons based on microscopic traffic simulations. A platoon formation algorithm was developed and run on the VISSIM platform to simulate automated truck maneuvering. As a result of the mobility analysis, it was found that the difference in network mobility performance was not significant up to MPR 80%. Regarding the mobility performance of the truck-designated lane, it was found that the average speed was lower than in other lanes. In the truck-designated lane of the on-ramp section, the average speed was identified to be approximately 33% lower. From the viewpoint of network safety, increasing the MPR of the truck platoon has a positive effect on longitudinal safety but has a negative effect on lateral safety. The safety analysis of the truck-designated lane indicated that the speed difference by lane of MPR 100% is 2.5 times higher than that of MPR 0%. This study is meaningful in that it explores traffic flow performance on mobility and safety in the process of platoon formation. The outcomes of this study are expected to be utilized as fundamentals to support the novel traffic operation strategy in platooning environments.

An empirical approach of modeling and assessment for the safe use of commercial electric detonators in radio frequency radiation hazards

In the modern era of communication technologies using amplitude modulation (AM) and frequency modulation (FM) the transmitting antenna of radio, television, radar, cellular phones, wireless data acquisition systems and global positioning systems (GPS) are the main sources of radio frequency radiation hazards. The transmitting antennas of these communication devices generate electromagnetic fields (EMFs). Electric detonator wires, under certain circumstances work as receiving antenna and pickup enough electrical energy from such fields to initiate unexpected explosion. There have been many cases of detonators being fired accidentally by radio frequency pick up. In this work an attempt has been made to minimize such explosions and to provide a basis for assessing and modeling the parameters of radio frequency radiation hazards associated with commercial electric detonators. This research examines the radiated powers of various frequency bands to determine the safe distance from transmitting antenna. Based on mathematical simulation, two empirical relations have been proposed for the calculation of minimum safe distance (MSD). Using these relations desired MSDs have been calculated for the relevant frequency bands. The obtained values have been compared with the available experimental values showing good agreement between them. The average percentage deviations of calculated MSDs from proposed relations are found between 0.096% and 10.718%, with regression coefficient 0.970 ≤ R ≤ 1. This reflects the soundness of the proposed empirical relations. The blasting engineers, detonator designers and researchers may use these relations as a handy tool to prevent undesired explosions by maintaining minimum safe distance in radio frequency prone hazardous areas.

Prediction of Bench Blasting Vibration on Slope and Safety Threshold of Blasting Vibration Velocity to Undercrossing Tunnel

The reconstruction and expansion project of oil reserve base often faces the excavation and blasting of the slope and undercrossing tunnel at the same time. Due to the flammable and explosive liquid storage nearby, the tight construction period, and the high requirements of collaborative construction, once the blasting accident occurs, the consequences are unimaginable. To facilitate safe and timely cooperative blasting construction of the slope and undercrossing tunnel, a vibration monitoring test of the slope and tunnel surrounding rock is conducted. The vibration response characteristics of the rock surrounding the slope and tunnel are analyzed, and a mathematical prediction model for the peak particle velocity (PPV) with consideration of the influence of the relative slope gradient (H/D) is established based on dimension analysis theory, which improves the prediction accuracy of PPV at the slope surface. ANSYS/LS‐DYNA is used to establish a 3D finite element model for the slope and tunnel, and the dynamic response of the tunnel surrounding rock under blasting load is verified through field monitoring data. A linear statistical relationship between PPV and effective tensile stress (ETS) of the tunnel surrounding rock is established. The PPV safety criterion of the tunnel surrounding rock under blasting load is proposed to be 10 cm/s according to the first strength theory, and hence, the minimum safety distance from the tunnel working face to the slope surface is calculated to be 36 m. Finally, the excavation timing arrangement of the slope and tunnel is proposed, which has been successfully applied to the expansion project, and the construction period has been effectively shortened by 45 days while ensuring construction safety. The research results have great guiding significance to similar cooperative blasting excavation engineering for high slope and adjacent tunnel with safety and efficiency.

УСЛОВИЕ БЕЗАВАРИЙНОГО ДВИЖЕНИЯ АВТОМОБИЛЕЙ НА РЕГУЛИРУЕМЫХ ПЕРЕСЕЧЕНИЯХ

Introduction: Improving intersection capacity will not be possible without accounting for traffic safety. Purpose of the study: We aim to determine the prerequisite for accident-free traffic at signal-controlled intersections with turning traffic flows. Methods: In our study, we used the methods of observation, comparison, and mathematical analysis. Results: We have carried out a field observation of traffic intensity at signal-controlled intersections in the city of Yekaterinburg, focusing on vehicles that moved when the green light was on. We have also analyzed traffic flow moving in three directions in the same lanes. We have discovered that traffic accident likelihood is the highest (54%) at four-way intersections. Three-way intersections account for 44% of traffic accidents, while the remaining 2% of accidents occur at multi-way intersections. Furthermore, we have determined the additional factors that impact safety in turning traffic flows at intersections. Our study demonstrates that in order to ensure maximum intersection capacity, the duration of the traffic signal cycle must be adjusted with the minimum safe distance between vehicles in mind.

Determination of Safe Depth and Lateral Distance of Unsupported Excavation Near Mat Foundation in Cohesive Soils Using PLAXIS

ABSTRACT Deep excavations are essential to harbor urban needs of the present age. The excavation of pits for foundation construction in an already limited space in urban centers poses damage to the neighboring structures. In this study, two mat foundations on two different types of clay soils have been modeled in PLAXIS to determine the maximum depth of excavation and the minimum safe distance of the excavation pit from these mat foundations. The failure modes under consideration are excessive settlement, angle of distortion of the mat foundation, and pit face failure. A co-relation to determine the safe maximum depth of unsupported excavation pit and minimum horizontal distance from adjacent mat foundation is presented based on results from 195 models. The ratio of critical unsupported excavation depth and critical horizontal distance from an existing building first drops to 1:3 in all cases and then rises in a non-linear manner. The modes of failures at various stages have been highlighted based on 44 critical cases.

Advanced dynamic modeling study of fire and smoke of crude oil storage tanks

The combustion properties of large-scale crude oil pool fire have great significance for security design and firefighting of current crude oil reserves. Burning rate, flame shape and radiation intensity are the most important parameters for fire properties. The novelty of this study is that the Fire Dynamics Simulator (FDS) is adopted to simulate pool fires in a tank farm. It does not only investigate and analyze heat radiation flux, but also the temperature difference rise and flame/smoke temperature contours behavior. This simulation is performed in order to predict the potentials of a large crude oil storage tank fire outbreak and the smoke temperature distribution that counters in and around the tank. These data are used in designing tank farms and applying the firefighting strategy. A super CPU with large RAM is used to operate the simulation program, to simulate one of the largest crude oil farms in the world. The model will be investigated for identifying the worst-case scenarios that might occur in a large crude oil tank. One of these scenarios might be fire outbreak in rim seal in one of the four storage tanks, where the fire is transferred to full surface fire. The model predicts the potential of tank fire outbreak, smoke tracing and both smoke/flame temperature that spreads at wind speed of 3 m/s, 9 m/s, 18 m/s in south-west direction. FDS model provides qualitative data that increase the level of safety, such as the minimum safe separation distances and the location of firefighters during the firefighting process. It also determines the most critical area, which is needed for water-cooling system. This study also tackles the duration after which human beings feel pain after being exposed to heat radiation.

Calculation of influence range of impact holing on the adjacent railway

In order to solve the impact of actual construction projects on the existing surrounding environment, the impact and vibration of the impact on the existing railway subgrade stability caused by the construction of the bridge foundation are analyzed. Based on the actual case of the construction project of No. 37 main pier across the Jiaoji Railway Main Bridge at Binlai expressway, the influence of the impact holing on the adjacent railway is analyzed. The influence range of the construction vibration is based on the Chinese Seismic Intensity Scale (GB/T 17742-2008) and Safety Regulations for Blasting (GB6722-2014), and taking the maximum velocity allowable value as criterion, the minimum safety range of impact drilling is obtained. Using the theory of small hole expansion to calculate the influence of the effect of soil compaction, the minimum allowable value of safe distance for the Construction technology of impact forming hole is considered 6.5m; in addition, based on the numerical simulation of nonlinear time history analysis, a reasonable exciting force parameter is given for practical engineering. The influence of impact amplitude A and impact frequency f on construction safety distance is analyzed. The results show that: The minimum safety distance of impact drilling is linear with the increase of impact amplitude A. When the impact frequency f is greater than 10Hz, the minimum safety distance tends to a fixed value as f increases. The results of this study guide the actual construction of the field, it guarantees the normal traffic of the Jiaoji Railway and provides a theoretical support for similar projects.

Application of Lean 6s Methodology in an Engineering Education Environment during the SARS-CoV-2 Pandemic.

In this work, the application of the Lean 6S methodology is exposed, which includes the Safety-Security activity in response to the demands caused by the epidemiological situation due to exposure to SARS-CoV-2, as well as its implementation through a standardized process in n higher education environment in the engineering field. The application of methodologies based on lean principles in the organizational system of an educational institution, causes an impact on the demands of organizational efficiency, where innovation and continuous improvement mark the path to success. The Lean 6S methodology, based on the development of six phases, guarantees, thanks to the impact of all its phases and especially of three of them: cleaning, standardize and safety, the control of the health risk against SARS-CoV-2. This guarantee is achieved through the permanent review of safety in the workplace. The areas of selected implementation to verify the effect have been the essential spaces for the development of the teaching activity: center accesses, learning rooms and practical laboratories. The laboratories are adapted to the security and organization conditions that are required in the regulations required by the Occupational Risk Prevention Services against exposure to SARS-CoV-2, since the appropriate protective equipment for the risk level is reviewed, the ordering of the workstations, the class attendance through the shifts organization and the rearrangement of the common places where the maintenance of a minimum interpersonal safety distance between the teaching staff, auxiliary services and students is guaranteed. The effort of the teaching staff in terms of following the established rules is notably increased. To balance this dedication, it is necessary to increase and rely on auxiliary personnel who guarantee rules compliance control in different spaces than the classroom and the laboratory.

Well spacing of the doublet at the Huangtsuishan geothermal site, Taiwan

The issue of thermal breakthrough is often encountered in the extraction of geothermal fluids with reinjection. This study analyzes the minimum safe distance between doublet wells that will maintain thermal productivity under various conditions at the Huangtsuishan geothermal site. A conceptual model is constructed and hypothetical exploitation scenarios are explored. The results show that a distance of 300 m is required to avoid a thermal break in 80 years with 120 tons/hour pumped and 90 % reinjected at the Huangtsuishan Geothermal site. A regression formula was provided as a guideline for the minimum required doublet distance for various pumping rates.

The Driving Risk Analysis and Evaluation in Rightward Zone of Expressway Reconstruction and Extension Engineering

In the expressway reconstruction and expansion engineering, the form of rightward zone is increasingly adopted, and its complicated traffic conditions can easily cause traffic accidents. In order to quickly and effectively grasp the traffic risk of the right diversion section, this study employs average speed, the coefficient of variation, the equivalent minimum safety distance, and the deceleration as evaluation indexes of driving risk, and then analyses the influence rules of traffic volume, the proportion of large vehicles, and the length of the transition section on each evaluation index by using Vissim simulation software. On the basis of this, we determine the weight of each evaluation index by the entropy method and establish the driving risk index evaluation model of the work zone with multiple linear regression. The results show that the partial regression coefficients of traffic volume, the proportion of large vehicles, and the length of the transition section to the driving risk index are 0.059, 0.317, and 0.15, respectively. Finally, in this paper, we analyze the traffic risk of example section based on the driving risk evaluation model. The results of evaluation are consistent with the number of measured conflicts. This study proposes a new method for predicting the traffic risk of the expressway reconstruction and extension engineering, which can provide a reference for the development of safety management measures in the rightward zone.