Shelter Effect Research Articles

Towards a new roughness parametrization through the effective distribution function

Turbulent flows over rough surfaces can be encountered in a wide range of engineering applications. Despite the progress made after several decades of studies, the prediction of drag and roughness function from the surface geometrical parameters remains an open question. Several methods have shown encouraging results. However, they lack generality and present some scatter in the data. In this paper we propose a new parameter, the effective distribution ( $ED$ ), which lays foundation on the effective slope with some changes to take into account the sheltering effect of large roughness elements and the drag induced by pinnacles higher than the average roughness elements. To develop this new correlation between geometrical features of the wall and the drag, we performed a set of simulations of the turbulent flow over a rough surface made of triangular elements varying their height and spatial distribution. The $ED$ correlates quite well both with the drag and the roughness function for a wide range of cases having different mean roughness height, skewness and kurtosis. To further validate the $ED$ , and assessing how it can be generalized to real rough wall, an irregular wall made from the superposition of random sinusoidal function was considered. Results were consistent with the correlation here presented.

Group interaction effect on breaking wave forces on a vertical pile: Experimental tests and predictive models

Pile groups are extensively utilized as supports for many coastal structures, such as bridges, jetties, and oil production platforms. The problem of understanding the interaction effects within pile groups and predicting the breaking wave forces on them is considered in this paper, using experimental tests and machine learning-based predictive modeling. The restriction of previous studies on this important engineering problem is that the pile group arrangements considered are limited. Prediction methods are therefore developed only for specific pile group arrangements and do not incorporate the effect of the incident wave direction. In this study, to partially overcome this limitation, an extensive experimental investigation is conducted on 70 different pile group arrangements under six breaking wave conditions. Three pile group coefficients, characterized by the total, quasi-static, and dynamic forces, are introduced for a thorough assessment of the interaction effects within the pile group. First, the pile group coefficients for three basic arrangements (tandem, side-by-side, and staggered) are evaluated. The results reveal a sheltering effect in the tandem arrangement and an amplification effect in the side-by-side arrangement. However, the forces on the measured pile in the staggered arrangement resemble those on the isolated pile, with neither significant sheltering nor amplification effects observed. Then, the results for all arrangements highlight the significant effect of wave direction on the pile group coefficients for small inter-pile spacing. Finally, different machine learning algorithms are adopted to develop predictive models for the group coefficients. The XGBoost model demonstrates superior accuracy for predicting the total and quasi-static force coefficients, while the dynamic force coefficient remains challenging to predict accurately due to its stochastic nature.

Outward direct investment as a shelter from external trade policy shocks: Firm‐level investigation of the US–China trade war

AbstractThis study examines the effects of external trade policy shock from the US–China trade war on firm value. Using a merged data set of Chinese‐listed companies, our empirical results reveal that Chinese firms conducting outward direct investment in the US have significantly higher stock returns around the date of the outbreak of the trade war as compared with the lower returns of exporting firms. This indicates a sheltering effect of pre‐existing outward direct investment activities. Moreover, we find that the sheltering effect is more pronounced for production‐oriented projects, high tech industries and tariff‐targeted sectors, while it is weaker for state‐owned companies.

Mathematical Model to Study the Effect of Refuge on Cannibalism in Atractosteus tropicus

Cannibalism is a behavior that different species of fish exhibit in the early stages of their life, and it has been widely reported. In Tabasco, Mexico, the ancestral species Atractosteus tropicus is farmed, which is a freshwater fish with a high nutritional and economic value. This species exhibits high cannibalistic behavior both in its larval and juvenile stages, which considerably decreases its production. Therefore, strategies have been developed to mitigate the effects of this behavior. One of them is the placement of shelters (rocks and artificial vegetation), which allow the vulnerable population to protect themselves from cannibals. The goal of this work is to study the effect of shelters on the cannibalistic behavior of the A. tropicus population through a mathematical model. The population is divided into two classes, the vulnerable population (prey) and the cannibal population (predator). Moreover, a system of ordinary differential equations is established, which is analyzed, and sufficient conditions for the coexistence of the two species are shown. Numerical simulations show coexistence by varying levels of refuge. The results obtained in this work can be applied to other populations that exhibit cannibalistic behavior.

Microclimatic effects of tree shelters on the early establishment and resilience of seeded acorns vs. outplanted seedlings

Little is known about the effects of tree shelters on the early response of oak seedlings produced by acorn seeding. In this paper, we explore the effects on holm oak (Quercus ilex L. subsp. ballota (Desf.) Samp.) seedlings of the microenvironment created by the tree shelters and the restoration method (seeding vs. outplanting) in terms of emergence, survival, growth, and resilience after harvesting. For this purpose, seedling height [H], root collar diameter [RCD], number of leaves, and aerial biomass were monitored. We made two sowings of acorns in February 2017 and February 2018, together with a seedling outplanting in February 2018 in a common garden site in semiarid SE Spain. In total, 600 acorns were randomly sowed and 300 nursery-grown seedlings were outplanted and studied until 2022. Mother tree and initial acorn mass were also monitored as additional variables in the analyses. Tree shelters consisted of closed plastic Tubes, Mixed tubes, Cork shelters, Tiles, and a Control with no shelter. Emergence rate was positively influenced by the Tube shelter (86%) as compared to the Control (64%), and especially by the initial acorn mass. By contrast, mother tree or year of sowing seemed to have no effect. The survival rate for the emerged acorns (88%) was statistically similar to that of outplanted seedlings (91%), and was unaffected by mother tree, tree shelter, or acorn mass. In terms of growth, the slenderness ratio (H:RCD) was considerably higher in seedlings from directly seeded acorns than for those that were outplanted. With the exception of Tile, all the shelters showed a higher slenderness ratio than the Control, especially the Tube shelter, which also showed a lower number of leaves and a lower aboveground dry biomass than the Control, Cork, and Tile shelters. Virtually no interactions were observed between the mother tree and the tree shelter. At harvesting, all the growth-related parameters were still strongly dependent on the acorn mass and the initial seedling features recorded after the first growing season. Resprouting rate and growth were also highly dependent on the acorn mass and the plant features at the beginning of the experiment and at harvesting. In summary, we did not find evidence to support tree shelters to improve the microclimate of holm oak seedlings both seeded or outplanted. Direct acorn seeding can be as successful as outplanting of nursery-grown seedlings. Selection of heavy acorns from mothers with a high germination and emergence rate is highly advisable.

Do Non‐SOEs Engage in Less Tax Avoidance When the Government Is a Minority Shareholder in China?

This study attempts to shed new light on how the state, as a minority shareholder, can affect the tax planning of non‐state‐owned enterprises (non‐SOEs). We examine publicly traded non‐SOEs in China and find that non‐SOEs engage in more tax avoidance when the government is a minority shareholder, indicating that minority state ownership has had a ‘shelter effect’ on tax avoidance of non‐SOEs. Further analysis shows that the sheltering effect of minority state ownership is more prominent for firms located in areas with heavier social burdens, worse tax enforcement and firms with stronger incentives to avoid taxes. Furthermore, non‐SOEs with minority state ownership increase excessive capital expenditures and employ redundant employees but still have higher firm value. Overall, our findings suggest the state, as a minority shareholder, shapes the tax‐planning activities of non‐SOEs in a ‘two‐way favour exchange’ manner and it is beneficial for non‐SOEs to maintain a close relationship with the government in China, where the government controls key resources.

From leaves to whole plants: positive effects of shelter‐builders on arthropod communities are stronger in dry seasons

AbstractLeaf shelters function as microclimatic refuges, reducing arthropod exposure to climatic fluctuations of surrounding habitats. Although facilitation is expected to increase under stressful conditions, empirical studies investigating the patterns of variation and magnitude of effects of ecosystem engineering (EE) at different spatial and temporal scales are still scarce. In this study, we evaluated the facilitation consequences of leaf shelter created by gall‐inducers on arthropod communities of Miconia ligustroides (DC.) Naudin (Melastomataceae). We evaluated how such effects change at the leaf and plant levels in a habitat subject to strong climatic seasonality. The presence of leaf shelters on M. ligustroides increased arthropod diversity and biomass, modified the species composition at both the leaf and plant levels, during wet and dry seasons. However, the addition of artificial leaf shelters during the dry season showed greater abundance, richness, and biomass of arthropods when compared to shelters added during the wet season. Regarding the global effects of artificial leaf shelters on the diversity of arthropods associated with M. ligustroides, the dry season showed strong and positive effects, increasing the abundance, richness, and biomass of arthropods by an average of 65% for both years. Our study contributes to a better understanding of the patterns of variation and magnitude of EE at different spatial and temporal scales and provides new insights into the importance of shelters for aridity‐sensitive species.

Effect of shelters on the growth and cultivation performance of the endemic snail, Pomacea patula catemacensis, cultured in a recirculating system during its grow-out

This study describes the process of Pomacea patula catemacensis grow-out in outdoor tanks. Experimental juvenile snails (1.5-2 months old) obtained from wild breeding snails were reared using a recirculating aquaculture system (RAS). The present study focused on increasing the surface area of growth tanks to be used by snails without affecting their growth and survival by adding shelters throughout the water column, which also worked to harbor snails. Two treatments were tested; T1: shelters made with curved clay tiles, T2: curved PVC shelters, and control (without shelters) in triplicate. The stocking density was set at 420 ind m-2 in tanks with 1 m3 total volume, and the culture period was 150 days. The final weight of the snails was significantly higher in control and PVC shelter groups (9.14 ± 2.2 and 8.83 ± 2.31 g, respectively), with PVC shelters showing the highest productivity in total biomass (12.03 ± 0.86 kg tank-1, P < 0.05). Final survival (%) was not significantly different among treatments (56.49 ± 1.62 to 58.05 ± 0.62).

Movement and effectiveness of shelters for restocking of the sea cucumber Isostichopus badionotus

The sea cucumber Isostichopus badionotus has been overfished along its Mexican distribution, but no abundance recovery has been observed despite management efforts. Restocking and sea ranching strategies can use releasing individuals, and magnitude of protected areas be related on species dispersion knowledge. We measured the short-term movement paths on I. badionotus and their relation with environmental variables. In addition, the influence of biofilm presence/absence on artificial shelters surfaces and the use for animals were compared. Data was obtained through time-lapse cameras in experiments performed in outer aquaria under the natural fluctuation of temperature and sunlight. We observed that larger (Le) individuals exhibited greater daily movement distances (D) (D=0.89*Le −2.533 cm); furthermore, the sea cucumbers move faster in bare aquaria than aquaria with sand. The mean daily movement without sand was 518 cm for small sizes, 615 cm for medium, and 688 cm for large sizes. In the presence of sand, was 127, 196, and 315 cm, respectively. Movement was minimal in the morning/early afternoon (07:00–15:00), a maximum in the afternoon/evening (15:00–23:00), and an intermediate at night/early morning (23:00–07:00). The movement of the small sea cucumbers (>5.96−10.75 cm), was linked to light. Medium-sized and large sea cucumbers (>10.6−19.69 cm) respond to changes in temperature. We observed a higher rate of shelter use by small sea cucumbers (53 % of the day) and a greater affinity for pre-conditioned shelters (80 % of shelter use). Medium-sized and large animals did not show any shelter preferences. Results indicate low dispersion of I. badionotus on daily timescale. The affinity found in small animals towards shelters with biofilm, and their use only in this size class, makes them essential for survival in restoration strategies.

Geostress-associated settlements of a raft-foundation building due to shield tunnelling in soft ground

The stress state of soil may affect the building settlements induced by tunnelling, which, however, has not been well understood. In this study, 3D numerical analyses combined with in-situ measurements were performed to investigate the geostress-associated settlements of a raft-foundation building due to tunnelling in soft ground. Basically, two types of geostress fields were investigated: the first type considered the effect of additional stress generated in the foundation soil (FAS) due to building weight; while in the second type, a sequential twin tunnelling was presumed, and the effect of additional soil stress induced by the first tunnel (TAS) on the building response to the second tunnel was considered. The results indicated that FAS may aggravate the stress release of the foundation soil, and thus gave rise to a larger building settlement or inclination. In the sequential tunnelling process, the effect of TAS can be more complex: when the first tunnel lowered the stress of foundation soil, TAS effect of the first tunnel may help reduce the building settlements induced by the second tunnel; otherwise, it may aggravate building settlements. In addition to TAS effect, the sheltering effect was also found to play an important part in twin tunnelling.

Numerical simulation of shelter effect assessment for single-row windbreaks on the periphery of oasis farmland

Dust storms, resulting from aeolian erosion, pose significant environmental hazards, while farmland is one of the main sources of dust storm release. An effective strategy to mitigate surface wind speed and curb dust emissions involves the establishment of windbreaks on the periphery of oasis farmland. This study conducts a series of numerical simulations using computational fluid dynamics (CFD) to explore the airflow fields around windbreaks with diverse systematic structural parameters, encompassing porosity, planting spacing, and fence effects. The main findings are as follows: (1) When the vegetation porosity is consistent (e.g., porosity α = 0.7, 0.8, and 0.9), exact geometry results can effectively reflect the distribution of wall shear stress, while the porous medium model overlooks these details. (2) The “Venturi effect” contributes to the acceleration of surface erosion and improper planting spacing results in an elevation of near-surface velocity. Planting spacing of 0.5 m demonstrates superior wind speed reduction performance, mitigating aeolian erosion and accumulation. (3) When the fence is positioned at l = 5h (h represents the height of the windbreaks), the flow field around the windbreaks is minimally influenced. The optimal placement distance for fences should be close to the windbreaks, featuring minimal porosity (l = 0 h, α = 0.1), extending the shelter distance from 3 to 4 h to 5–6 h. The research results can provide a theoretical basis for optimizing the plant configuration of biological desertification control and soil erosion control measures.

Full-scale aerodynamic study on the effects of tower wind shields and road-sign gantries on passing high-sided vehicles in the tower region at the Queensferry Crossing

A novel investigation into the impact of the tower road-sign gantry and the tower shielding on double-decker buses and trucks passing by the bridge tower based on a previously validated full-scale CFD model. Two sets of simulations were conducted for comparison of aerodynamic force conditions of vehicles as they pass by the bridge tower: first group of simulations were performed including and excluding the road-sign gantry; and the second group include and exclude the tower shielding. Conditions in different traffic lanes (one on leeward side and two on windward side) considered. The effect of changes in wind yaw angle are also considered. Mechanism exploration on the variation of vehicle aerodynamic force conditions was made based on the numerical visualization of wind velocity field and pressure field. Novel results suggest that the road-sign gantry provides a sheltering effect in some circumstances, but a destabilizing effect in others. In addition, the tower shielding shows significant impact on reducing aerodynamic forces and sudden force changes of the high-sided vehicles while they are passing by the bridge tower.

Encapsulation of Enzymes into Hydrophilic and Biocompatible Metal Azolate Framework: Improved Functions of Biocatalyst in Cascade Reactions and its Sensing Applications.

Multiple enzyme-triggered cascade biocatalytic reactions are vital in vivo or vitro, considering the basic biofunction preservation in living organisms and signals transduction for biosensing platforms. Encapsulation of such enzymes into carrier endows a sheltering effect and can boost catalytic performance, although the selection and preparation of an appropriate carrier is still a concern. Herein, focusing on MAF-7, a category of metal azolate framework (MAF) with superiority against the topologically identical ZIF-8, this enzyme@MAF system can ameliorate the sustainability of encapsulating natural enzymes into carriers. The proposed biocatalyst composite AChE@ChOx@MAF-7/hemin is constructed via one-pot in situ coprecipitation method. Subsequently, MAF-7 is demonstrated to exhibit an excellent capacity of the carrier and protection against external factors in the counterpart of ZIF-8 through encapsulated and free enzymes. In addition, detections for specific substrates or inhibitors with favorable sensitivity are accomplished, indicating that the properties above expectation of different aspects of the established platform are successfully realized. This biofunctional composite based on MAF-7 can definitely provide a potential approach for optimization of cascade reaction and enzyme encapsulation.

Urban-canopy airflow dynamics: A numerical investigation of drag forces and distribution for generic neighborhoods, and their relationships with breathability

Thorough investigations of urban-canopy drag primarily stemming from pressure drag on building surfaces are necessary given the turbulent flows within complex urban areas. Moreover, a gap persists regarding the relationships between canopy drag and breathability. Therefore, this work delves into the canopy-layer airflow dynamics for generic urban neighborhoods by performing three-dimensional Reynolds-Averaged Navier-Stokes simulations. A total of 32 subcases are examined, encompassing uniform- and varying-height and diverse plan area densities (λp, categorized into groups of sparse: 0.0625/0.067, medium: 0.23/0.25, and dense: 0.53/0.56). Results for the drag distribution highlight the windward-row shelter effect for the medium and the dense, local shelter by taller buildings, and distinct shapes of sectional drag forces (F⁎Z). Local velocity and mean age of air are found strongly positively and negatively correlated to F⁎Z, respectively, with distinct slopes in relation to λp. For the uniform-height, the normalized bulk drag (F⁎bulk, referred to as drag coefficient in literature) peaks for the medium with wake-interference regime; F⁎bulk demonstrates a maximum increase of over two times with height variation; moreover, F⁎bulk for varying-height groups exhibits a marked increase from the sparse to the medium, while remaining comparable values for the dense. The frontal area averaged drag (FAf,ave) exhibits a decreasing trend against λp across all cases. Further, FAf,ave exhibits strong correlations with λp and porosity, and with bulk ventilation indices such as spatially averaged velocity, air change rate, and normalized net escape velocity. Throughout the ‘suburban-urban-suburban’ canopy, medium neighborhoods exerting larger drag cause greater streamwise outdoor pressure drops and flow reductions compared to the sparse. However, dense neighborhoods with lower drag exhibit even larger pressure losses, which should be carefully scrutinized. The findings can inform urban planners in designing more aerodynamically efficient neighborhoods and guide strategies for improving air quality within urban environments.

Reef effect of vertical relief on the shelter-seeking and foraging processes of juvenile fat greenling (Hexagrammos otakii) in a mesocosm experiment

Artificial reefs with sufficient vertical relief can support secondary fish production by attracting pelagic fishes and/or providing both shelter and food resources for them. Although vertical relief is a widely investigated factor in reef design, little is known about how the shelter-seeking and foraging processes of benthic fishes respond to relief changes. With a laboratory mesocosm experiment using hollow blocks to construct different combinations of reef volume and relief, we tested the effect of vertical relief of artificial reefs on a benthic juvenile fish (fat greenling, Hexagrammos otakii). The volume of the experimental reef depended on the number of blocks, and the reef relief was changed by the stacking pattern of the blocks at each volume. We measured the aggregation, sheltering, and foraging effects of each reef structure, respectively, based on fish distribution around the reef, their shelter-seeking behavior under disturbance, and their foraging rate. Our results demonstrate that increasing the vertical relief while maintaining the reef volume had a positive effect on the aggregating juvenile fat greenling but decreased the sheltering effect of the reef. The relationship between the foraging effect and relief was nonlinear, and high relief would also limit the foraging rate of juvenile fat greenling. We suggest that a reef needs to have sufficient relief to provide habitat for juvenile fat greenling, as well as sufficient horizontal cover to shelter the fish during a disturbance. Not only limited resources (e.g., food and shelter) but also the shelter-seeking and foraging processes of the benthic fish could have a potential impact on secondary production. Our findings highlight the importance of considering the aggregation, sheltering, and foraging effects of relief on benthic fishes in the field observation and the design of artificial reefs.

Influence of seagrass meadow length on beach morphodynamics: An experimental study

A novel flume experiment was conducted to compare the sheltering effect of surrogate seagrass meadows of two different lengths against a bare beach (benchmark). The analyses focused on assessing the impact of meadow cross-shore extent on wave height attenuation, behaviour of wave orbital velocity components, sediment transport, and shoreline erosion. Throughout the tests conducted in the large-scale CIEM wave flume at LIM/UPC Barcelona, meadow density and submergence ratio remained constant, while irregular waves were run over an initial 1:15 sand beach profile. In both meadow layouts, a persistent decrease in wave height from the offshore area in front of the meadow to the breaking zone was found. This reduction was directly correlated with the length of the seagrass meadow. As a result of the reduction in wave energy, less erosion occurred at the shoreline in accordance with the decrease in wave height. The mean velocities exhibited changes in the velocity profile from the meadow area to the immediate zone behind the meadow, a phenomenon not observed in more onshoreward positions. Orbital velocities displayed a reduction exclusively for the long meadow case. This decrease was persistent up to the breaking zone. As a consequence of these changes, the long meadow layout led to a decrease in the volume of sediment transport and a breaker bar closer to the shoreline. The short meadow layout resulted in a higher volume of sediment transport compared to the long meadow layout, although still less than the benchmark layout. Furthermore, in the short meadow layout, the final bar was situated in a location similar to that observed in the benchmark layout.

Vertical variation of source-apportioned PM2.5 and selected volatile organic compounds near an elevated expressway in an urban area.

Fine particulate matter (PM2.5) and volatile organic compounds (VOCs) are associated with adverse health effects and show spatial variation in three dimensions. The present study attempted to evaluate source contributions of PM2.5 and toxic VOCs in a metropolitan area focusing on the associated vertical variations. A special emphasis is put on the effects of the elevated expressway on the vertical variability of contribution estimates of the identified sources. Nine source factors, i.e., soil dust, sea salt/oil combustion, secondary nitrate, industrial emission, aged VOCs/secondary aerosol, traffic-related I, solvent use/industrial process, secondary sulfate, and traffic-related II, were identified using positive matrix factorization (PMF). The main contributors to PM2.5 were secondary sulfate (19.1%) and traffic-related emissions (traffic-related I and II, 16.1%), whereas the largest contributors to VOCs were traffic-related emissions (37.6%). The influence of the elevated expressway is suggested to be particularly critical on vertical variations of traffic-related emissions, including aging and secondary formation of locally accumulated air pollutants near roads. Increasing the building porosity under the viaduct could reduce the accumulation of air pollutants caused by the shelter effect. Additionally, in-street barriers would be beneficial in reducing population exposure to traffic-related emissions by altering the airflows near roads.

Extended Darcy–Forchheimer law including inertial flow deflection effects

Recent advances in manufacturing techniques are providing porous media with both high permeability, necessary for effective passive flow control, and high structural strength, essential for engineering applications. We therefore examine the predictive accuracy of the standard Darcy–Forchheimer (DF) law, which is often used to model porous media flows, for inclusion Reynolds numbers (Re) ranging from the low linear regime to the high nonlinear regime where unsteady effects such as vortex shedding become evident. We consider two different inclusion shapes, square and circular, and three different arrangements of the inclusions – inline, staggered and random. The numerical simulations show that the DF law performs well for low-Re flows, irrespective of the inclusion configuration. For intermediate/high-Re flows, the DF law is adequate only when the arrangement is highly random. However, for the regularly arranged topologies or less random geometries at intermediate/high-Re flows, the DF-law performance diminishes significantly due to flow sheltering and redirection (‘inertial flow deflection’) effects that arise from flow inertia, separation and vortex shedding in the wake of the inclusions. It is shown that the standard DF law, in which the nonlinear permeability tensor is independent of orientation, does not capture such effects. We modified the DF law to capture flow redirection effects by allowing the Forchheimer permeability tensor to depend on the flow orientation with respect to the principal geometrical directions of the porous geometry, and examined this extended DF law for these flows.

High densities of large tuaki, the New Zealand cockle Austrovenus stutchburyi, provide a post-settlement predation refuge for conspecific juveniles

Bivalves are ecosystem engineers, and their effective management relies on a full understanding of the mechanisms that influence population dynamics. Juvenile tuaki (New Zealand cockle) Austrovenus stutchburyi, a numerically dominant and ecologically important bivalve in New Zealand estuaries, were found at higher densities when surrounded by high densities of large adults within Waitati Inlet, in southern New Zealand. Consequently, we hypothesised that adults provided a refuge from predation for juveniles, resulting in higher juvenile survival and retention in dense beds. The observed pattern was consistent with post-settlement Allee effects, where declines in density and truncated size distributions may have resulted in unsuccessful recruitment if a density threshold was reached. Field experiments were undertaken in 2020 and 2021 to test the potential sheltering effect of adults on retention and survival of juveniles, with and without the addition of organic loading of sediments. Presence of adults had significant effects on juvenile retention and interaction with organic loading in 2020, but not in 2021. To isolate the effects of adult presence on predation of juveniles, a series of laboratory experiments were carried out using the predatory crab Ovalipes catharus. Juvenile survivorship from crab predation was enhanced in the presence of large adults, consistent with the hypothesised sheltering effect. Further, predation rates increased significantly from winter to summer, which correlated with increasing water temperatures and the breeding and moult cycle of crabs. These findings across surveys, field and laboratory manipulations have significant implications for effective fisheries management and restoration of bed-forming bivalves.

Hopf bifurcation in a predator-prey model under fuzzy parameters involving prey refuge and fear effects

<p>In ecology, the most significant aspect is that the interactions between predators and prey are extremely complicated. Numerous experiments have shown that both direct predation and the fear induced in prey by the presence of predators lead to a reduction in prey density in predator-prey interactions. In addition, a suitable shelter can effectively stop predators from attacking as well as support the persistence of prey population. There has been less exploration of the effects of not only fear but also refuge factors on the dynamics of predator prey interactions. In this paper, we unveil several conclusions about a predator-prey system with fuzzy parameters, considering the cost of fear in two prey species and the effect of shelter on two prey species and one predator. As the first step of the investigation, the boundedness and non-negativity of the solutions to the system are put forward. Using the Jocabian matrix and Lyapunov function methods, we further analyze the existence and stability of the available equilibria and also the existence of Hopf bifurcation, considering the fear parameter as the bifurcation parameter that has been observed by applying the normal form theory. Finally, numerical simulations help us better understand the dynamics of the model, in which some interesting chaotic phenomena are also exhibited.</p>