Journal articles: 'Particle evacuation'

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Yuan, Gan-Nan, Li-Na Zhang, Li-Qiang Liu, and Kan Wang. "Passengers’ Evacuation in Ships Based on Neighborhood Particle Swarm Optimization." Mathematical Problems in Engineering 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/939723.

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A new intelligent model to simulate evacuation behavior in ships called neighborhood particle swarm optimization is proposed. This model determines the rules of behavior and velocity updating formulas to solve staff conflicts. The individuals in evacuation are taken as particles in PSO and update their behaviors by individual attributes, neighborhood attributes, and social attributes. Putting the degree of freedom movement of ships into environment factor and using the real Ro-Ro ship information and IMO test scenarios to simulate the evacuation process, the model in this paper can truly simulate the behavior of persons in emergency and provide a new idea to design excellent evacuation model.

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Senthil Kumar Thangavel, K. Pavithra, G. Radhamani,. "IMPROVED PARTICLE SWAM OPTIMIZATION FOR CROWD SIMULATION USING HYBRID AGENT REINFORCEMENT LEARNING ALGORITHM." INFORMATION TECHNOLOGY IN INDUSTRY 9, no. 2 (March 30, 2021): 144–54. http://dx.doi.org/10.17762/itii.v9i2.318.

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In an emergency route planning technique, simulating the dynamic crowd has route capacity constraints and global target of evacuating all crowd evacuees. To stimulate the crowd, the new arena is developed to know the real-time situation to face the crowd evacuation on exit point. The crowd evacuation is done with the process of Hybrid Agent Reinforcement Learning (HARL) algorithm consisting of Improved Multi-Agent Reinforcement Learning (IMARL) and State-Action-Reward-State-Action (SARSA). In the proposed work, the appropriate route selection mechanism focused on finding optimum evacuation route(s) is done in the first phase. Dynamic crowd can also be evacuated to find its way with the support of the HARL process in the second phase. The proposed HARL method can also be implemented with multi-objective improved particle swarm optimization (IPSO) technique for crowd simulation. The experimented results demonstrate the effectiveness of stability in the HARL process, which provides an improved performance for crowd simulation

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Fidler, Richard L., Christopher R. Niedek, Justin J. Teng, Mary E. Sturgeon, Qi Zhang, David L. Robinowitz, and Jan Hirsch. "Aerosol Retention Characteristics of Barrier Devices." Anesthesiology 134, no. 1 (October 30, 2020): 61–71. http://dx.doi.org/10.1097/aln.0000000000003597.

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Background Disease severity in coronavirus disease 2019 (COVID-19) may be associated with inoculation dose. This has triggered interest in intubation barrier devices to block droplet exposure; however, aerosol protection with these devices is not known. This study hypothesized that barrier devices reduce aerosol outside of the barrier. Methods Aerosol containment in closed, semiclosed, semiopen, and open barrier devices was investigated: (1) “glove box” sealed with gloves and caudal drape, (2) “drape tent” with a drape placed over a frame, (3) “slit box” with armholes and caudal end covered by vinyl slit diaphragms, (4) original “aerosol box,” (5) collapsible “interlocking box,” (6) “simple drape” over the patient, and (7) “no barrier.” Containment was investigated by (1) vapor instillation at manikin’s right arm with video-assisted visual evaluation and (2) submicrometer ammonium sulfate aerosol particles ejected through the manikin’s mouth with ventilation and coughs. Samples were taken from standardized locations inside and around the barriers using a particle counter and a mass spectrometer. Aerosol evacuation from the devices was measured using standard hospital suction, a surgical smoke evacuator, and a Shop-Vac. Results Vapor experiments demonstrated leakage via arm holes and edges. Only closed and semiclosed devices and the aerosol box reduced aerosol particle counts (median [25th, 75th percentile]) at the operator’s mouth compared to no barrier (combined median 29 [−11, 56], n = 5 vs. 157 [151, 166], n = 5). The other barrier devices provided less reduction in particle counts (133 [128, 137], n = 5). Aerosol evacuation to baseline required 15 min with standard suction and the Shop-Vac and 5 min with a smoke evacuator. Conclusions Barrier devices may reduce exposure to droplets and aerosol. With meticulous tucking, the glove box and drape tent can retain aerosol during airway management. Devices that are not fully enclosed may direct aerosol toward the laryngoscopist. Aerosol evacuation reduces aerosol content inside fully enclosed devices. Barrier devices must be used in conjunction with body-worn personal protective equipment. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

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Carr, Michele M., Vijay A. Patel, Jhy-Charm Soo, Sherri Friend, and Eun Gyung Lee. "Effect of Electrocautery Settings on Particulate Concentrations in Surgical Plume during Tonsillectomy." Otolaryngology–Head and Neck Surgery 162, no. 6 (March 31, 2020): 867–72. http://dx.doi.org/10.1177/0194599820914275.

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Objectives To describe the effect of monopolar electrocautery (EC) settings on surgical plume particulate concentration during pediatric tonsillectomy. Study Design Cross-sectional study. Setting Tertiary medical center. Subjects and Methods During total tonsillectomy exclusively performed with EC, air was sampled with a surgeon-worn portable particle counter. The airborne mean and maximum particle concentrations were compared for tonsillectomy performed with EC at 12 W vs 20 W, with smoke evacuation system (SES) and no smoke evacuation (NS). Results A total of 36 children were included in this analysis: 9 cases with EC at 12 W and SES (12SES), 9 cases with EC at 20 W and SES (20SES), 9 cases with EC at 12 W without SES (12NS), and 9 cases with EC at 20 W without SES (20NS). Mean particle number concentration in the breathing zone during tonsillectomy was 1661 particles/cm3 for 12SES, 5515 particles/cm3 for 20SES, 8208 particles/cm3 for 12NS, and 78,506 particles/cm3 for 20NS. There was a statistically significant difference in the particle number concentrations among the 4 groups. The correlation between the particle number concentration and EC time was either moderate (for 12SES) or negative (for remaining groups). Conclusion Airborne particle concentrations during tonsillectomy are over 9.5 times higher when EC is set at 20 W vs 12 W with NS, which is mitigated to 3.3 times with SES. Applying lower EC settings with SES during pediatric tonsillectomy significantly reduces surgical plume exposure for patients, surgeons, and operating room personnel, which is a well-known occupational health hazard.

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Zong, Xinlu, Chunzhi Wang, and Hongwei Chen. "An evacuation model based on co-evolutionary multi-particle swarms optimization for pedestrian–vehicle mixed traffic flow." International Journal of Modern Physics C 28, no. 12 (December 2017): 1750142. http://dx.doi.org/10.1142/s012918311750142x.

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In a large common place, a huge number of pedestrians may flood into the surrounding region and mix with the vehicles which originally existed on the roads when emergent events occur. The mutual restriction between pedestrians and vehicles as well as the mutual effect between evacuation individuals and the environment which evacuees are situated in, will have an important impact on evacuation effects. This paper presents a pedestrian–vehicle mixed evacuation model to produce optimal evacuation plans considering both evacuation time and density degree. A co-evolutionary multi-particle swarms optimization approach is proposed to simulate the evacuation process of pedestrians and vehicles separately and the interaction between these two kinds of traffic modes. The proposed model and algorithm are effective for mixed evacuation problems. An illustrating example of a study region around a large stadium has been presented. The experimental results indicate the effective performances for evacuation problems which involve complex environments and various types of traffic modes.

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Roch, Samuel, Albert F. H. Ros, Christian Friedrich, and Alexander Brinker. "Microplastic evacuation in fish is particle size‐dependent." Freshwater Biology 66, no. 5 (February 18, 2021): 926–35. http://dx.doi.org/10.1111/fwb.13687.

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Wang, Chen, Lincoln C. Wood, Heng Li, Zhenye Aw, and Abolfazl Keshavarzsaleh. "Applied Artificial Bee Colony Optimization Algorithm in Fire Evacuation Routing System." Journal of Applied Mathematics 2018 (2018): 1–17. http://dx.doi.org/10.1155/2018/7962952.

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Every minute counts in an event of fire evacuation where evacuees need to make immediate routing decisions in a condition of low visibility, low environmental familiarity, and high anxiety. However, the existing fire evacuation routing models using various algorithm such as ant colony optimization or particle swarm optimization can neither properly interpret the delay caused by congestion during evacuation nor determine the best layout of emergency exit guidance signs; thus bee colony optimization is expected to solve the problem. This study aims to develop a fire evacuation routing model “Bee-Fire” using artificial bee colony optimization (BCO) and to test the routing model through a simulation run. Bee-Fire is able to find the optimal fire evacuation routing solutions; thus not only the clearance time but also the total evacuation time can be reduced. Simulation shows that Bee-Fire could save 10.12% clearance time and 15.41% total evacuation time; thus the congestion during the evacuation process could be effectively avoided and thus the evacuation becomes more systematic and efficient.

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Shao, Fenfen, Tuck Wah Ng, Jim Efthimiadis, Anthony Somers, and Willem Schwalb. "Evaporative micro-particle self assembly influenced by capillary evacuation." Journal of Colloid and Interface Science 377, no. 1 (July 2012): 421–29. http://dx.doi.org/10.1016/j.jcis.2012.02.071.

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Bertocchi, Rudi. "Carbon Particle Cloud Generation for a Solar Particle Receiver." Journal of Solar Energy Engineering 124, no. 3 (August 1, 2002): 230–36. http://dx.doi.org/10.1115/1.1488666.

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The development and performance of a full-scale carbon particle cloud generator together with the evaluation of nine commercial carbon blacks is reported. Large variations were found in the dispersability and settling properties of the investigated powders. Scanning electron microscope analysis of cloud samples from different powders showed unequal state of agglomeration and particle size. The particle population distribution of the most suitable powder was determined, showing that the particle cloud consisted of 99.8% spheroid primary particles (25–570 nm dia) and 0.2% large irregularly shaped agglomerates. Although the numerical fraction of the agglomerates was only 0.2%, they contributed 40% to the cloud’s geometrical cross section. Significant variations in the population distribution were found from different batches of the same particle powder. The developed full-scale particle generator was capable of sustained operation, creating a particle cloud with an extinction coefficient exceeding 40m−1 at a nominal flow rate of 25 SLPM. The dispersal efficiency of the system with the optimal ejection nozzle was 25%, compared to less than 1% for free ejection. The particle dispersal rate was 30 g/hr at 25 SLPM at an evacuation efficiency of 87%. Specific extinction cross-sections of 5.8m2/g were measured for particle mass loading higher than 2g/m3.

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Niu, Yanyan, Jia Yu, Dawei Lu, Renwu Mu, and Jiahong Wen. "Spatial Allocation Method of Evacuation Guiders in Urban Open Public Spaces: A Case Study of Binjiang Green Space in Xuhui District, Shanghai, China." International Journal of Environmental Research and Public Health 19, no. 19 (September 27, 2022): 12293. http://dx.doi.org/10.3390/ijerph191912293.

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Evacuation guiders play an important role when emergency events occur in urban open public spaces. Considering the shortcomings of the existing studies, an optimization method based on the Particle Swarm Optimization (PSO) algorithm and gradual covering model for spatial allocation of evacuation guiders in urban open public spaces is proposed. This method considers the impact of obstacles on intervisibility between guiders and evacuees, and the non-linear changing characteristics of the evacuation guiding quality based on the distances between guiders and evacuees to optimize the space allocation of evacuation guiders in urban open public spaces. Based on the emergency evacuation simulation, the evacuation efficiencies before and after the optimization of evacuation guider allocation can be compared to verify the validity of the proposed method. Furthermore, in order to improve the applicability of this method, the responsibility areas of the evacuation guiders are zoned according to different time periods. A case study of Binjiang Green Space in Xuhui District, Shanghai, China was conducted to demonstrate the feasibility of the proposed method. The results showed that the spatial allocation of evacuation guiders was highly correlated with the dynamic spatial change of evacuees. The reasonable spatial allocation optimization of evacuation guiders can effectively improve the emergency evacuation quality and reduce evacuation risks. The zoning of the evacuation guiders’ responsibility areas can help to clarify the responsibility area of each guider and provide a daily safety precaution scheme under a limited number of guiders. The method can provide detailed decision support for the security precaution of security staff and emergency evacuation management in urban open public spaces.

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Liu, Bangquan, Zhen Liu, Dechao Sun, and Chunyue Bi. "An Evacuation Route Model of Crowd Based on Emotion and Geodesic." Mathematical Problems in Engineering 2018 (October 1, 2018): 1–10. http://dx.doi.org/10.1155/2018/5397071.

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Making unconventional emergent plan for dense crowd is one of the critical issues of evacuation simulations. In order to make the behavior of crowd more believable, we present a real-time evacuation route approach based on emotion and geodesic under the influence of individual emotion and multi-hazard circumstances. The proposed emotion model can reflect the dynamic process of individual in group on three factors: individual emotion, perilous field, and crowd emotion. Specifically, we first convert the evacuation scene to Delaunay triangulation representations. Then, we use the optimization-driven geodesic approach to calculate the best evacuation path with user-specified geometric constraints, such as crowd density, obstacle information, and perilous field. Finally, the Smooth Particle Hydrodynamics method is used for local avoidance of collisions with nearby agents in real-time simulation. Extensive experimental results show that our algorithm is efficient and well suited for real-time simulations of crowd evacuation.

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Bao, Danwen, Jiayu Gu, and Junhua Jia. "Bilevel Traffic Evacuation Model and Algorithm Design for Large-Scale Activities." Mathematical Problems in Engineering 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/5049657.

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This paper establishes a bilevel planning model with one master and multiple slaves to solve traffic evacuation problems. The minimum evacuation network saturation and shortest evacuation time are used as the objective functions for the upper- and lower-level models, respectively. The optimizing conditions of this model are also analyzed. An improved particle swarm optimization (PSO) method is proposed by introducing an electromagnetism-like mechanism to solve the bilevel model and enhance its convergence efficiency. A case study is carried out using the Nanjing Olympic Sports Center. The results indicate that, for large-scale activities, the average evacuation time of the classic model is shorter but the road saturation distribution is more uneven. Thus, the overall evacuation efficiency of the network is not high. For induced emergencies, the evacuation time of the bilevel planning model is shortened. When the audience arrival rate is increased from 50% to 100%, the evacuation time is shortened from 22% to 35%, indicating that the optimization effect of the bilevel planning model is more effective compared to the classic model. Therefore, the model and algorithm presented in this paper can provide a theoretical basis for the traffic-induced evacuation decision making of large-scale activities.

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Lyons, L. R., M. Schulz, and J. F. Fennell. "Trapped-particle evacuation: Source of magnetotail bursts and tailward flows?" Geophysical Research Letters 16, no. 5 (May 1989): 353–56. http://dx.doi.org/10.1029/gl016i005p00353.

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John, J., P. Wollmer, M. Dahlback, A. Luts, and B. Jonson. "Tidal volume and alveolar clearance of insoluble particles." Journal of Applied Physiology 76, no. 2 (February 1, 1994): 584–88. http://dx.doi.org/10.1152/jappl.1994.76.2.584.

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We studied the effect of 3 h of large tidal volume ventilation on alveolar clearance of 0.63-micron fluorescent latex particles in rabbits during pentobarbital anesthesia. After particle deposition, six animals were killed as controls, six were subjected to large tidal volume ventilation with a peak pressure of 27 cmH2O, and six were subjected to conventional ventilation with a peak pressure of 11 cmH2O. Mean tidal volumes were 30.2 +/- 6.1 and 8.4 +/- 1.6 ml/kg in the large tidal volume and conventional groups, respectively. End-expiratory pressure was 2 cmH2O in all groups. Compliance decreased only after large tidal ventilation (P = 0.0036). Compared with controls the conventional ventilation group showed no alveolar clearance, but more particles were clustered within macrophages (P = 0.01). Compared with other groups the large tidal volume group had fewer alveolar particles (P = 0.0005), most of which were single particles. Accordingly, large tidal volumes enhance alveolar particle clearance, which is possibly related to distension-related evacuation of surfactant to proximal airways. Clearance may be due to accelerated motion of the particle-loaded macrophage in response to the fast film motion. Alternatively, single particles embedded in the surfactant film may be dragged by the fast-moving film toward the airways.

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Zheng, Yu-Jun, Hai-Feng Ling, Jin-Yun Xue, and Sheng-Yong Chen. "Population Classification in Fire Evacuation: A Multiobjective Particle Swarm Optimization Approach." IEEE Transactions on Evolutionary Computation 18, no. 1 (February 2014): 70–81. http://dx.doi.org/10.1109/tevc.2013.2281396.

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Zheng, Yaochen, Jianqiao Chen, Junhong Wei, and Xiwei Guo. "Modeling of pedestrian evacuation based on the particle swarm optimization algorithm." Physica A: Statistical Mechanics and its Applications 391, no. 17 (September 2012): 4225–33. http://dx.doi.org/10.1016/j.physa.2012.03.033.

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Ma, Yaping, Xiaoying Liu, Feizhou Huo, and Hui Li. "Analysis of Cooperation Behaviors and Crowd Dynamics during Pedestrian Evacuation with Group Existence." Sustainability 14, no. 9 (April 27, 2022): 5278. http://dx.doi.org/10.3390/su14095278.

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At most public places where large-scale events are held, the crowd as a pedestrian particle system is a mixture of individuals and groups rather than a pure collection of individuals. The interaction behaviors of pedestrians within the same group and between different groups are significantly disparate, which makes the crowd evacuation process more complex. To address this issue, a new pedestrian evacuation model is proposed incorporating the cellular automaton model and game theory. In the model, two game theory models named prisoner’s dilemma and harmony game are applied to depict the interaction mechanism between pedestrians, and the decision-making of one pedestrian regarding route choice is subject to the environment factor and interaction payoffs between his neighbors. The influences of the intensity of interaction between pedestrians, the willingness to cooperate, the number of groups, the size of groups, and the initial distribution pattern of groups on the evacuation dynamics and cooperation evolution of the crowd are discussed. Simulation results show that it is beneficial to the evacuation efficiency and the formation of cooperation behaviors when pedestrians have a low intensity of interaction. As the willingness of large groups to cooperate is high, an increase in group’ sizes and numbers can improve the cooperation fraction of the crowd but prolongs evacuation time. Groups in the crowd gathered together initially negatively affect the evacuation efficiency of the crowd.

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Fang, Jie Shi, and Sherif El-Tawil. "Egress Simulation Incorporating Social Relationships by Using Scalar Field Method." Advanced Materials Research 639-640 (January 2013): 1313–16. http://dx.doi.org/10.4028/www.scientific.net/amr.639-640.1313.

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Research on human evacuation is heavily dependent on simulation. However, many of the models developed to date lack realism because of their inability to adequately simulate social relationships. In order to create a better tool for studying human response during evacuation, an agent-based model is proposed based upon a new technique termed Scalar Field Method (SFM). Drawing on analogy to a charged particle in an electromagnetic field, both human will and social relationships are converted into virtual potential energies (VPEs) to simulate the interactions that occur between an agent and its surrounding entities. Each agent has stochastic characteristics, is independent and makes autonomous decisions on behavior by minimizing the VPE. Preliminary tests show the ability of the new model to mimic reasonable evacuation behavior, and its potential for exploring the significance of social relationships during egress.

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Izquierdo, B., J. Wang, J. A. Sánchez, and I. Ayesta. "Study of particle size and position on debris evacuation during Wire EDM operations." IOP Conference Series: Materials Science and Engineering 1193, no. 1 (October 1, 2021): 012022. http://dx.doi.org/10.1088/1757-899x/1193/1/012022.

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Abstract Wire Electrical Discharge Machining (WEDM) is a well-known non-conventional machining process for those applications that require both good finishing and tight tolerances. One of the main problems that occur during EDM operations is wire breakage, which leads to stops in the machining process and lowers process productivity. Recent findings have revealed that discharge accumulations near the same spot of the wire are the main cause for wire breakage. If this discharge accumulation is not stopped, the wire finally breaks. In the present work CFD simulations have been effectively used to simulate dielectric flow and particle movement. The effect of particle size and position, together with the effect of high and low pressure flushing conditions have been analyzed. The studied variables have a clear effect on debris evacuation, and it can be concluded that particle size and position, together with nozzle position affect process stability and wire breakage. This work can help to develop new WEDM strategies that consider the relation between mentioned variables and wire breakage.

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Yang, Weilong, Yue Hu, Cong Hu, and Mei Yang. "An Agent-Based Simulation of Deep Foundation Pit Emergency Evacuation Modeling in the Presence of Collapse Disaster." Symmetry 10, no. 11 (November 2, 2018): 581. http://dx.doi.org/10.3390/sym10110581.

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With the gradual expansion of high buildings and underground spaces, deep foundation pits have been widely used in these engineering projects, but if they are not well-designed, safety problems occur. Proper deep foundation pit design requires proper exit distribution. However, calculating an adequate number of exit distributions for evaluation is difficult due to the numerous influential factors existing in the deep foundation pit environment. To this end, this paper presents a prototype of a decision-making system that uses agent-based modeling to simulate deep foundation pit evacuation in the presence of collapse disaster. By modeling the collapse occurrence process and agent escape process, an agent-based evacuation model is built, and a modified simulation-based particle swarm optimization algorithm is used to solve the optimization problem of exit distribution. Extensive experiments are conducted to verify the system, and the results show that the system provides a feasible framework for deep foundation pit evacuation.

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Go, C. G., H. T. Go, and C. I. Lin. "Particle Swarm Simulation of Escape Movement in Panic Situation for the Evacuation Design." Advanced Science Letters 9, no. 1 (April 30, 2012): 74–79. http://dx.doi.org/10.1166/asl.2012.2617.

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Li, Lin, Zhonghai Yu, and Yang Chen. "Evacuation dynamic and exit optimization of a supermarket based on particle swarm optimization." Physica A: Statistical Mechanics and its Applications 416 (December 2014): 157–72. http://dx.doi.org/10.1016/j.physa.2014.08.054.

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Hsieh, Yi-Chih, and Peng-Sheng You. "Evolutionary artificial intelligence algorithms for the one-way road orientation planning problem with multiple venues: An example of evacuation planning in Taiwan." Science Progress 104, no. 3_suppl (July 2021): 003685042110632. http://dx.doi.org/10.1177/00368504211063258.

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Introduction: In large-scale events such as concerts and sports competitions, participants often leave the venue at the same time to return to their respective destinations. Improper traffic planning and traffic light operation usually lead to traffic congestion and road chaos near the sites. Rapid evacuation of participants has become an important issue. Objectives: In this work, a one-way road orientation planning problem with multiple venues is studied in which all roads near the venues are to be scheduled into a one-way orientation with strong connectivity to increase the evacuation efficiency of participants. Methods: In accordance with Robbins’ theorem and a random sequence of integers, an encoding scheme based on module operator is presented to construct a strongly connected graph and plan a one-way orientation for all roads. The proposed encoding scheme is further embedded into four artificial intelligence approaches, namely, grey wolf optimization, immune algorithm, genetic algorithm, and particle swarm optimization, to solve the one-way road orientation planning problem such that the total distance of all vehicles from venues to their destinations is minimized. Results: Numerical results of test problems with multiple venues in Taiwan are provided and analyzed. As shown, all four algorithms can obtain the best solution for the test problems. Conclusions: The new presented encoding scheme with four algorithms can be used to effectively solve the one-way road orientation planning problem for the evacuation of participants. Moreover, grey wolf optimization is superior to the other three algorithms and particle swarm optimization is faster than the other three algorithms.

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Li, Jing Long, Saburo Sano, Jiang Tao Xiong, Fu Sheng Zhang, and Zhong Ping Wang. "Magnetic Alignments of Ba-Ferrite Particles in Suspension." Key Engineering Materials 336-338 (April 2007): 1042–45. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.1042.

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Ba-ferrite particles were dispersed into distilled water to make stable slurry, which was then slip cast in transverse magnetic field. The water drainage from the slurry was performed by vacuum evacuation to solidify the slurry into a cake – like sample. To obtain high degree of alignments, the slurries were slip cast in static – / pulsed – magnetic field and by using two separate steps of magnetic orientation and drainage. The particles turned their faces to the magnetic field and formed long chains stacked immediately while the magnetic field was applied, of which high induction density led to high degree of alignments. It is necessary to correspond with the drainage, gravity and magnetism so as to suppress the tendency of distortion or cracking of the sample as the aligned long chains of the particles tend to break into pieces and cave in randomly, which eventually destroys the particle alignments.

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Khider, Mohammed, Susanna Kaiser, and Patrick Robertson. "A Novel Three Dimensional Movement Model for Pedestrian Navigation." Journal of Navigation 65, no. 2 (March 12, 2012): 245–64. http://dx.doi.org/10.1017/s0373463311000713.

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In this paper, a Three Dimensional Pedestrian Movement Model (3D-MM) capable of probabilistically representing pedestrian movement in challenging indoor and outdoor localization environments is developed, implemented and evaluated. In the scope of this paper, the model is used to generate a ‘movement’ or a transition for dynamic positioning systems that are based on sequential Bayesian filtering techniques, such as particle filtering. It can also be used to assign weights for particles' movements proposed by sensors in Likelihood Particle Filters implementations. Alternatively, the developed model can be applied to other applications domains such as infrastructure design, evacuation planning, robot-human interaction and pervasive computing. The novelty of the model is in its ability to characterize both random and goals-oriented pedestrian motions and additionally use the a priori knowledge of maps and floor plans. It will be shown that an appropriate pedestrian movement model not only improves the positioning accuracy, but is also essential for a robust positioning estimator. Additionally, this work shows that maps and floor plans can improve pedestrian movement models but do not replace them, as several authors suggest.

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Mitsuda, Takashi, Sachiko Kuge, Masato Wakabayashi, and Sadao Kawamura. "Wearable Force Display Using a Particle Mechanical Constraint." Presence: Teleoperators and Virtual Environments 11, no. 6 (December 2002): 569–77. http://dx.doi.org/10.1162/105474602321050703.

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A particle mechanical constraint (PMC) is a soft vinyl tube containing Styrofoam beads. It can be freely compressed, elongated, bent, twisted, or otherwise manipulated in all degrees of freedom. Evacuation of the air inside the tube makes the PMC rigid so that it maintains whatever shape it has been given. The stiffness of the PMC is proportional to the reduction in internal pressure below atmospheric pressure. Viscosity is also controlled virtually by changing the inside air pressure in proportion to the speed of transformation of the PMC. We used a PMC to develop a wearable force display that provides the sensation of coming into contact with a wall or of moving in water with viscosity, in addition to that of moving in air. PMC is an inherently passive device that never exerts excessive force if it were to malfunction. In short, it is suitable as a wearable human interface because it is light, soft, and safe.

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Zhao, Xiujuan, Jianguo Chen, Wei Xu, Shiyan Lou, Peng Du, Hongyong Yuan, and Kuai Peng Ip. "A Three-Stage Hierarchical Model for An Earthquake Shelter Location-Allocation Problem: Case Study of Chaoyang District, Beijing, China." Sustainability 11, no. 17 (August 22, 2019): 4561. http://dx.doi.org/10.3390/su11174561.

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Earthquakes are one type of natural disaster that causes serious economic loss, deaths, and homelessness, and providing shelters is vital to evacuees who have been affected by an earthquake. Constructing shelters with reasonable capacity in the right locations and allocating evacuees to them in a reasonable time period is one disaster management method. This study proposes a multi-objective hierarchical model with three stages, i.e., an immediate shelter (IS) stage, a short-term shelter (STS) stage, and a long-term shelter (LTS) stage. According to the requirements of evacuees of IS, STS, and LTS, the objective of both the IS and STS stages is to minimize total evacuation time and the objectives of the LTS are to minimize total evacuation time and to minimize total shelter area. A modified particle swarm optimization (MPSO) algorithm is used to solve the IS and STS stages and an interleaved modified particle swarm optimization algorithm and genetic algorithm (MPSO-GA) is applied to solve the LTS stage. Taking Chaoyang District, Beijing, China as a case study, the results generated using the model present the government with a set of options. Thus, according to the preferences of the government, the determination can be made regarding where to construct ISs, STSs, and LTSs, and how to allocate the evacuees to them.

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Deng Xuefeng. "Research on Building Crowd evacuation Model Based on Multi-Agent particle swarm optimization algorithm." Journal of Convergence Information Technology 8, no. 4 (February 28, 2013): 17–25. http://dx.doi.org/10.4156/jcit.vol8.issue4.3.

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Gerasymov, Oleg, Vladyslav Kuryatnikov, Andrii Spivak, Liudmyla Sidletska, and Andrii Kilian. "Electrophoretic Effects for Environmental Safety Technologies: Evacuation of Micro-Particle Conglomerations from the Surfaces." E3S Web of Conferences 319 (2021): 01076. http://dx.doi.org/10.1051/e3sconf/202131901076.

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The actuality of the problem of contamination of objects by macro-molecular compounds is a growing problem today (especially given the terrible consequences of the pandemic). In fact, macromolecular complexes are mostly located on the surface layers of the surface covered with fine dust. Therefore, the development of technology for the removal of macromolecular components is actually a problem of fine (so we will call it) dust removal. This problem cannot be effectively solved by traditional mechanical removal methods alone, as contaminated objects have a rather complex, not even Euclidian, surface morphology. Therefore, it is important to develop effective technologies based on the use of properties of special configurations of external inhomogeneous electric field and removable components by means of a specially configured inhomogeneous electric field. The paper analyzes modern technologies of fine dust cleaning both mechanically and with the help of external electrical fields under the particular conditions and creation of levitation and electrophoretic motion. It has been found exact solutions of the model, which indicate in favor of the theoretical validity of decontamination technology using electric field with manipulative properties; the conditions of the most effective use of levitation-electrophoretic technology in the tasks of dust cleaning and decontamination, including decontamination of the surface-distributed macromolecular contaminants such as coronaviruses. Index Terms dust pollution dust cleaning levitation electrophoresis macromolecular pollution coronavirus

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Li, Feng, Yifan Zhang, Yingying Ma, and Hanlin Zhang. "Modelling Multi-Exit Large-Venue Pedestrian Evacuation With Dual-Strategy Adaptive Particle Swarm Optimization." IEEE Access 8 (2020): 114554–69. http://dx.doi.org/10.1109/access.2020.3003082.

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Duan, X. H., J. X. Wu, and Y. L. Xiong. "Dynamic Emergency Vehicle Path Planning and Traffic Evacuation Based on Salp Swarm Algorithm." Journal of Advanced Transportation 2022 (April 25, 2022): 1–28. http://dx.doi.org/10.1155/2022/7862746.

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In view of the rescue delay due to traffic congestion in the urban road network, this paper implemented real-time traffic control with congestion index constraints in emergency vehicle dispatching and proposed a two-stage optimization model and algorithm. In the first stage, salp swarm algorithm (SSA) was combined with Dijkstra algorithm, and a novel hybrid algorithm with new updating rules was designed to get the multiple alternative paths. In the second stage, an improved salp swarm algorithm (ISSA) with a population grouping strategy was proposed to obtain the best evacuation schemes and the optimal rescue paths of emergency vehicles. Results of the illustrative examples show that, after evacuation, the average travel time of all alternative paths is reduced by 24.22%, while traffic congestion indexes of the adjacent road sections almost unchanged. The computation time of the hybrid algorithm for obtaining the set number of alternative paths is 56.62% and 50.47% shorter than that of bat algorithm (BA) and SSA. For the solution of the evacuation model, the computation time of the ISSA is 33.51%, 30.15%, and 30.60% shorter than that of particle swarm optimization (PSO), BA, and SSA, and the optimal solution of the ISSA is 25.92%, 10.06%, and 0.97% better than that of PSO, BA, and SSA. That is, we shorten the emergency response time and control the adverse impact of traffic evacuation on background traffic. The improved algorithm has excellent performance. This study provides a new idea and method for emergency rescue of traffic accidents.

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Duan, X. H., J. X. Wu, and Y. L. Xiong. "Dynamic Emergency Vehicle Path Planning and Traffic Evacuation Based on Salp Swarm Algorithm." Journal of Advanced Transportation 2022 (April 25, 2022): 1–28. http://dx.doi.org/10.1155/2022/7862746.

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In view of the rescue delay due to traffic congestion in the urban road network, this paper implemented real-time traffic control with congestion index constraints in emergency vehicle dispatching and proposed a two-stage optimization model and algorithm. In the first stage, salp swarm algorithm (SSA) was combined with Dijkstra algorithm, and a novel hybrid algorithm with new updating rules was designed to get the multiple alternative paths. In the second stage, an improved salp swarm algorithm (ISSA) with a population grouping strategy was proposed to obtain the best evacuation schemes and the optimal rescue paths of emergency vehicles. Results of the illustrative examples show that, after evacuation, the average travel time of all alternative paths is reduced by 24.22%, while traffic congestion indexes of the adjacent road sections almost unchanged. The computation time of the hybrid algorithm for obtaining the set number of alternative paths is 56.62% and 50.47% shorter than that of bat algorithm (BA) and SSA. For the solution of the evacuation model, the computation time of the ISSA is 33.51%, 30.15%, and 30.60% shorter than that of particle swarm optimization (PSO), BA, and SSA, and the optimal solution of the ISSA is 25.92%, 10.06%, and 0.97% better than that of PSO, BA, and SSA. That is, we shorten the emergency response time and control the adverse impact of traffic evacuation on background traffic. The improved algorithm has excellent performance. This study provides a new idea and method for emergency rescue of traffic accidents.

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Duan, X. H., J. X. Wu, and Y. L. Xiong. "Dynamic Emergency Vehicle Path Planning and Traffic Evacuation Based on Salp Swarm Algorithm." Journal of Advanced Transportation 2022 (April 25, 2022): 1–28. http://dx.doi.org/10.1155/2022/7862746.

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In view of the rescue delay due to traffic congestion in the urban road network, this paper implemented real-time traffic control with congestion index constraints in emergency vehicle dispatching and proposed a two-stage optimization model and algorithm. In the first stage, salp swarm algorithm (SSA) was combined with Dijkstra algorithm, and a novel hybrid algorithm with new updating rules was designed to get the multiple alternative paths. In the second stage, an improved salp swarm algorithm (ISSA) with a population grouping strategy was proposed to obtain the best evacuation schemes and the optimal rescue paths of emergency vehicles. Results of the illustrative examples show that, after evacuation, the average travel time of all alternative paths is reduced by 24.22%, while traffic congestion indexes of the adjacent road sections almost unchanged. The computation time of the hybrid algorithm for obtaining the set number of alternative paths is 56.62% and 50.47% shorter than that of bat algorithm (BA) and SSA. For the solution of the evacuation model, the computation time of the ISSA is 33.51%, 30.15%, and 30.60% shorter than that of particle swarm optimization (PSO), BA, and SSA, and the optimal solution of the ISSA is 25.92%, 10.06%, and 0.97% better than that of PSO, BA, and SSA. That is, we shorten the emergency response time and control the adverse impact of traffic evacuation on background traffic. The improved algorithm has excellent performance. This study provides a new idea and method for emergency rescue of traffic accidents.

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Niyomubyeyi, Olive, Tome Eduardo Sicuaio, José Ignacio Díaz González, Petter Pilesjö, and Ali Mansourian. "A Comparative Study of Four Metaheuristic Algorithms, AMOSA, MOABC, MSPSO, and NSGA-II for Evacuation Planning." Algorithms 13, no. 1 (January 3, 2020): 16. http://dx.doi.org/10.3390/a13010016.

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Evacuation planning is an important activity in disaster management to reduce the effects of disasters on urban communities. It is regarded as a multi-objective optimization problem that involves conflicting spatial objectives and constraints in a decision-making process. Such problems are difficult to solve by traditional methods. However, metaheuristics methods have been shown to be proper solutions. Well-known classical metaheuristic algorithms—such as simulated annealing (SA), artificial bee colony (ABC), standard particle swarm optimization (SPSO), genetic algorithm (GA), and multi-objective versions of them—have been used in the spatial optimization domain. However, few types of research have applied these classical methods, and their performance has not always been well evaluated, specifically not on evacuation planning problems. This research applies the multi-objective versions of four classical metaheuristic algorithms (AMOSA, MOABC, NSGA-II, and MSPSO) on an urban evacuation problem in Rwanda in order to compare the performances of the four algorithms. The performances of the algorithms have been evaluated based on the effectiveness, efficiency, repeatability, and computational time of each algorithm. The results showed that in terms of effectiveness, AMOSA and MOABC achieve good quality solutions that satisfy the objective functions. NSGA-II and MSPSO showed third and fourth-best effectiveness. For efficiency, NSGA-II is the fastest algorithm in terms of execution time and convergence speed followed by AMOSA, MOABC, and MSPSO. AMOSA, MOABC, and MSPSO showed a high level of repeatability compared to NSGA-II. It seems that by modifying MOABC and increasing its effectiveness, it could be a proper algorithm for evacuation planning.

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Chinda, Padmanabha Raju, and Ragaleela Dalapati Rao. "A binary particle swarm optimization approach for power system security enhancement." International Journal of Electrical and Computer Engineering (IJECE) 12, no. 2 (April 1, 2022): 1929. http://dx.doi.org/10.11591/ijece.v12i2.pp1929-1936.

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Improvement of power system security manages the errand of making healing move against conceivable system overloads in the framework following the events of contingencies. Generation re-dispatching is answer for the evacuation of line overloads. The issue is the minimization of different goals viz. minimization of fuel cost, minimization of line loadings and minimization of overall severity index. Binary particle swarm optimization (BPSO) method was utilized to take care of optimal power flow issue with different targets under system contingencies. The inspiration to introduce BPSO gets from the way that, in rivalry with other meta-heuristics, BPSO has demonstrated to be a champ by and large, putting a technique as a genuine alternative when one needs to take care of a complex optimization problem. The positioning is assessed utilizing fuzzy logic. Simulation Results on IEEE-14 and IEEE-30 bus systems are presented with different objectives.

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Malko, Mihail, Sergey Vasilevich, Andrei Mitrofanov, and Vadim Mizonov. "Development of the Method for Forecasting and Calculating the Operation of Sorption Systems for Purifying the Generator Gas Based on Dolomite Use. Part I." Problems of the Regional Energetics, no. 3(51) (August 2021): 78–90. http://dx.doi.org/10.52254/1857-0070.2021.3-51.07.

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A trend towards energy diversification creates the expansion of small energy facilities that involve the production of solid fuel generator gas, rather than its direct combustion. The economic indicators of such facilities significantly depend on the efficiency of the generator gas purification. A promising sorbent for the purification of the generator gas is dolomite. When working as a sorbent, dolomite particles usually form a layer, through which the generator gas that is heating them is filtered. The objective of the study is to determine kinetic parameters of the thermal decomposition of dolomite, depending on the size of the sample. It was achieved using the thermogravimetric study of the thermal decomposition of single dolomite particles under static conditions at various temperatures. The most significant scientific result was that a dependence of the kinetic parameters of the gross reaction on the size of the initial particle is revealed, and a regression equation was proposed for its quantitative assessment. In addition, since the heat treatment process of the material was fairly long lasting, and the sizes of the particles allowed them to be referred to thermally thin bodies, it was inferred that the effect of a grain size on the reaction kinetics should be explained through the description of the evacuation process of gaseous reaction products from the material. The significance of the results of the study lies in the fact that a particle size must be considered as a factor that affects the progress of the technological process, which increases the reliability of the calculation of sorption-catalytic systems based on the use of dolomite.

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Wang, Jian, Danqing Shen, and Mingzhu Yu. "Multiobjective Optimization on Hierarchical Refugee Evacuation and Resource Allocation for Disaster Management." Mathematical Problems in Engineering 2020 (August 19, 2020): 1–18. http://dx.doi.org/10.1155/2020/8395714.

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This paper studies a location-allocation problem to determine the selection of emergency shelters, medical centers, and distribution centers after the disaster. The evacuation of refugees and allocation of relief resources are also considered. A mixed-integer nonlinear multiobjective programming model is proposed to characterize the problem. The hierarchical demand of different refugees and the limitations of relief resources are considered in the model. We employ a combination of the simulated annealing (SA) algorithm and the particle swarm optimization (PSO) algorithm method to solve the complex model. To optimize the result of our proposed algorithm, we absorb the group search, crossover, and mutation operator of GA into SA. We conduct a case study in a district of Beijing in China to validate the proposed methodology. Some computational experiments are conducted to analyze the impact of different factors, such as the target weight setting, selection of candidate shelters, and quantity of relief resources.

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Zong, Xinlu, Shengwu Xiong, and Zhixiang Fang. "A conflict–congestion model for pedestrian–vehicle mixed evacuation based on discrete particle swarm optimization algorithm." Computers & Operations Research 44 (April 2014): 1–12. http://dx.doi.org/10.1016/j.cor.2013.10.015.

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Zhang, Feng, Li Zhang, Yanshuang Xie, Zhiyuan Wang, and Shaoping Shang. "Smoothed Particle Hydrodynamics Simulation of a Mariculture Platform under Waves." Water 13, no. 20 (October 13, 2021): 2847. http://dx.doi.org/10.3390/w13202847.

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This work investigates the dynamic behaviors of floating structures with moorings using open-source software for smoothed particle hydrodynamics. DualSPHysics permits us to use graphics processing units to recreate designs that include complex calculations at high resolution with reasonable computational time. A free damped oscillation was simulated, and its results were compared with theoretical data to validate the numerical model developed. The simulated three degrees of freedom (3-DoF) (surge, heave, and pitch) of a rectangular floating box have excellent consistency with experimental data. MoorDyn was coupled with DualSPHysics to include a mooring simulation. Finally, we modelled and simulated a real mariculture platform on the coast of China. We simulated the 3-DoF of this mariculture platform under a typical annual wave and a Typhoon Dujuan wave. The motion was light and gentle under the typical annual wave but vigorous under the Typhoon Dujuan wave. Experiments at different tidal water levels revealed an earlier motion response and smaller motion range during the high tide. The results reveal that DualSPHysics combined with MoorDyn is an adaptive scheme to simulate a coupled fluid–solid–mooring system. This work provides support to disaster warning, emergency evacuation, and proper engineering design.

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Zhang, Feng, Li Zhang, Yanshuang Xie, Zhiyuan Wang, and Shaoping Shang. "Smoothed Particle Hydrodynamics Simulation of a Mariculture Platform under Waves." Water 13, no. 20 (October 13, 2021): 2847. http://dx.doi.org/10.3390/w13202847.

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This work investigates the dynamic behaviors of floating structures with moorings using open-source software for smoothed particle hydrodynamics. DualSPHysics permits us to use graphics processing units to recreate designs that include complex calculations at high resolution with reasonable computational time. A free damped oscillation was simulated, and its results were compared with theoretical data to validate the numerical model developed. The simulated three degrees of freedom (3-DoF) (surge, heave, and pitch) of a rectangular floating box have excellent consistency with experimental data. MoorDyn was coupled with DualSPHysics to include a mooring simulation. Finally, we modelled and simulated a real mariculture platform on the coast of China. We simulated the 3-DoF of this mariculture platform under a typical annual wave and a Typhoon Dujuan wave. The motion was light and gentle under the typical annual wave but vigorous under the Typhoon Dujuan wave. Experiments at different tidal water levels revealed an earlier motion response and smaller motion range during the high tide. The results reveal that DualSPHysics combined with MoorDyn is an adaptive scheme to simulate a coupled fluid–solid–mooring system. This work provides support to disaster warning, emergency evacuation, and proper engineering design.

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Zhang, Yihao, Zhaojie Chai, and George Lykotrafitis. "Deep reinforcement learning with a particle dynamics environment applied to emergency evacuation of a room with obstacles." Physica A: Statistical Mechanics and its Applications 571 (June 2021): 125845. http://dx.doi.org/10.1016/j.physa.2021.125845.

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Baer, Andreas, Chris Langdon, Scott Mills, Carsten Schulz, and Kristin Hamre. "Particle size preference, gut filling and evacuation rates of the rotifer Brachionus “Cayman” using polystyrene latex beads." Aquaculture 282, no. 1-4 (September 2008): 75–82. http://dx.doi.org/10.1016/j.aquaculture.2008.06.020.

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Samany, Najmeh Neysani, Mahdi Sheybani, and Sisi Zlatanova. "Detection of safe areas in flood as emergency evacuation stations using modified particle swarm optimization with local search." Applied Soft Computing 111 (November 2021): 107681. http://dx.doi.org/10.1016/j.asoc.2021.107681.

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Santana Robles, Francisca, Eva Selene Hernández-Gress, Neil Hernández-Gress, and Rafael Granillo Macias. "Metaheuristics in the Humanitarian Supply Chain." Algorithms 14, no. 12 (December 15, 2021): 364. http://dx.doi.org/10.3390/a14120364.

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Everyday there are more disasters that require Humanitarian Supply Chain (HSC) attention; generally these problems are difficult to solve in reasonable computational time and metaheuristics (MHs) are the indicated solution algorithms. To our knowledge, there has not been a review article on MHs applied to HSC. In this work, 78 articles were extracted from 2016 publications using systematic literature review methodology and were analyzed to answer two research questions: (1) How are the HSC problems that have been solved from Metaheuristics classified? (2) What is the gap found to accomplish future research in Metaheuristics in HSC? After classifying them into deterministic (52.56%) and non-deterministic (47.44%) problems; post-disaster (51.28%), pre-disaster (14.10%) and integrated (34.62%); facility location (41.03%), distribution (71.79%), inventory (11.54%) and mass evacuation (10.26%); single (46.15%) and multiple objective functions (53.85%), single (76.92%) and multiple (23.07%) period; and the type of Metaheuristic: Metaphor (71.79%) with genetic algorithms and particle swarm optimization as the most used; and non-metaphor based (28.20%), in which search algorithms are mostly used; it is concluded that, to consider the uncertainty of the real context, future research should be done in non-deterministic and multi-period problems that integrate pre- and post-disaster stages, that increasingly include problems such as inventory and mass evacuation and in which new multi-objective MHs are tested.

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Li, Xiujie, Cheuk Ming Mak, Kuen Wai Ma, and Hai Ming Wong. "How the high-volume evacuation alters the flow-field and particle removal characteristics in the mock-up dental clinic." Building and Environment 205 (November 2021): 108225. http://dx.doi.org/10.1016/j.buildenv.2021.108225.

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Sharma, Ashish, Bhuban Kumar Sahu, and Subrat Kar. "Baseband Modeling of Superconducting RF Cavity in Digital Domain." ECS Transactions 107, no. 1 (April 24, 2022): 15643–59. http://dx.doi.org/10.1149/10701.15643ecst.

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Modern day particle accelerators use resonating RF cavities to generate high electric field for enhancing the kinetic energy of particles for beam acceleration. These RF cavities are made using normal conducting or superconducting material. A closed loop control electronics is applied to maintain stability of the field gradient inside the cavity in terms of its amplitude and phase. Normal conducting mode has more control bandwidth than the superconducting mode and this makes it a difficult process. Another important requirement for achieving superconductivity is the usage of huge amounts of liquid nitrogen, liquid helium, and high degree of evacuation. Developing and testing of any control electronics for such cavities in poses a big challenge since multiple test iterations are desired, which is not economical or sustainable due to associated infrastructural needs. So, in order to perform iterative design, development and deployment in an economical and sustainable manner, cavity simulators are used to mimic the behavior of the cavity characteristics in terms of its electrical and mechanical parameters. In the present paper, the electrical and mechanical model of a superconducting RF cavity is mathematically built on the Simulink platform of MATLAB. The models are then converted to fixed point format and tested on a FPGA device to develop a digital equivalent of a superconducting RF cavity.

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Mishra, P., A. P. B. Balaji, P. K. Dhal, R. S. Suresh Kumar, S. Magdassi, K. Margulis, B. K. Tyagi, A. Mukherjee, and N. Chandrasekaran. "Stability of nano-sized permethrin in its colloidal state and its effect on the physiological and biochemical profile of Culex tritaeniorhynchus larvae." Bulletin of Entomological Research 107, no. 5 (March 1, 2017): 676–88. http://dx.doi.org/10.1017/s0007485317000165.

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AbstractThe occurrence of pesticidal pollution in the environment and the resistance in the mosquito species makes an urge for the safer and an effective pesticide. Permethrin, a poorly water-soluble pyrethroid pesticide, was formulated into a hydrodispersible nanopowder through rapid solvent evaporation of pesticide-loaded oil in water microemulsion. Stability studies confirmed that the nanopermethrin dispersion was stable in paddy field water for 5 days with the mean particle sizes of 175.3 ± 0.75 nm and zeta potential of −30.6 ± 0.62 mV. The instability rate of the nanopermethrin particles was greater in alkaline (pH 10) medium when compared with the neutral (pH 7) and acidic (pH 4) dispersion medium. The colloidal dispersion at 45°C was found to be less stable compared with the dispersions at 25 and 5°C. The 12- and 24-h lethal indices (LC50) for nanopermethrin were found to be 0.057 and 0.014 mg l−1, respectively. These results were corroborative with the severity of damages observed in the mosquito larvae manifested in epithelial cells and the evacuation of the midgut contents. Further, the results were substantiated by the decrease in cellular biomolecules and biomarker enzyme activity in nanopermethrin treated larvae when compared to bulk and control treatment.

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Asadi, Morteza, and Jalal Karami. "Modeling of the city evacuation plan in case of earthquake with particle swarm optimization (PSO) and imperialist competition algorithm (ICA)." International Journal of Disaster Resilience in the Built Environment 11, no. 1 (November 16, 2019): 134–51. http://dx.doi.org/10.1108/ijdrbe-12-2018-0053.

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Purpose The aim of this study was to determine the number of shelters, specify some optimal paths among building blocks towards shelters, and assign population to shelters. Design/methodology/approach Imperialist competition algorithm (ICA) and particle swarm optimization (PSO) were used to optimize the objectives of this study. Findings The optimal value for PSO objective function was with the number of function evaluations (NFE) of 5300 and the optimal value of ICA objective function was with NFE of 1062. Repetition test for both algorithms showed that imperialist competition algorithm enjoys better stability and constancy and higher speed of convergence compared to particle swarm algorithm. This has been also shown in larger environments. 92% of the existing populations have access to shelters at a distance of less than600 meters. This means that evacuation from the building blocks to shelters takes less than 8 minutes. The average distance from a block (for example, a residential complex) to an optimal shelter is approximately273meters. The greatest risk of route and shelter has been 239 and 121, respectively. Research limitations/implications To address these goals, four following objective functions were considered: a) minimization of the distance for getting all the people to shelters b) the lowest total risk of the discharge path c) minimization of the total time required to transfer people to shelters or hospitals if necessary, and d) the lowest total risk in shelters. Social implications Over the recent decades, the frequency of so-called ‘natural’ disasters has increased significantly worldwide and resulted in escalating human and economic losses. Among them, the earthquake is one of the major concerns of the various stakeholders related to urban planning. Originality/value In addition, the maximum time of discharge from the helter to the hospital has been 17 minutes, which means the presence of good access to selected shelters.

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Fullard, L. A., E. C. P. Breard, C. E. Davies, A. J. R. Godfrey, M. Fukuoka, A. Wade, J. Dufek, and G. Lube. "The dynamics of granular flow from a silo with two symmetric openings." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 475, no. 2221 (January 2019): 20180462. http://dx.doi.org/10.1098/rspa.2018.0462.

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The dynamics of granular flow in a rectangular silo with two symmetrically placed exit openings is investigated using particle image velocimetry (PIV), flow rate measurements and discrete element modelling (DEM). The flow of mustard seeds in a Perspex silo is recorded using a high-speed camera and the resulting image frames are analysed using PIV to obtain velocity, velocity divergence and shear rate plots. A change in flow structure is observed as the distance L between the two openings is varied. The mass flow rate is shown to be at a maximum at zero opening separation, decreasing as L is increased; it then reaches a minimum before rising to an equilibrium rate close to two times that of an isolated (non-interacting) opening. The flow rate experiment is repeated using amaranth and screened sand and similar behaviour is observed. Although this result is in contrast with some recent DEM and physical experiments in silo systems, this effect has been reported in an analogous system: the evacuation of pedestrians from a room through two doors. Our experimental results are replicated using DEM and we show that inter-particle friction controls the flow rate behaviour and explains the discrepancies in the literature results.

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Kamal, Khaliesah, Mohamad Azmi Bustam, Marhaina Ismail, Denys Grekov, Azmi Mohd Shariff, and Pascaline Pré. "Optimization of Washing Processes in Solvothermal Synthesis of Nickel-Based MOF-74." Materials 13, no. 12 (June 17, 2020): 2741. http://dx.doi.org/10.3390/ma13122741.

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Solvothermal synthesis is the most preferable preparation technique of metal–organic frameworks (MOFs) that consists of reactants mixing, ultrasonication, solvothermal reaction, product washing, and solvent evacuation. Owing to fast reaction kinetics in solvothermal reaction, this technique allows for production of uniform MOF particles with high crystallinity, high phase purity, and small particle sizes. However, it exhibits some difficulties of washing processes that may involve the blockage of pores due to incomplete removal of reactive medium from MOF products. The present study proposes an improvement of washing processes by introducing centrifugal separations with optimized parameters at two different stages: after reaction and after product washing. Nickel-based MOF-74 was synthesized as the experimental material for this purpose. The quality of the produced sample was evaluated by gas adsorption performance using CO2 at 1 bar and 25 °C. The final sample of the optimized synthesis routes was able to adsorb 5.80 mmol/g of CO2 uptake, which was competitive with literature data and significantly higher than the sample of the basic synthesis. Fourier-transform infrared spectroscopy (FTIR) and powder X-ray diffraction (PXRD) analysis revealed that the sample displayed much higher crystallinity structure and was clean from impurities after centrifugations. The outcome indicated the success of separation between MOF products and reactive medium during washing processes, leading to the effective pore activation of MOFs.

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Journal articles on the topic 'Particle evacuation'

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