Hole Area Research Articles

Heat transfer within a multi-package: Assessing the impact of package design on the cooling of strawberries

Perishable horticultural products may necessitate multi-packaging for preservation. The optimized primary and secondary packaging designs allow to reduce cooling time and ensure uniform product temperature, thereby enhancing fruit quality. This study examined how the secondary package design impacts the cooling of strawberries in airtight clamshells (AC) during precooling. The AC design simulates heat transfer within Modified Atmosphere Package (MAP) where there is no direct interaction between the external cooling air and the internal environment of the clamshell. Laboratory experiments were conducted to simulate one level of a pallet, using artificial material instead of real strawberries in order to have a better control of thermophysical properties and thus to better investigate heat transfer mechanisms. The thermal performance of an existing tray design was compared to three new alternative designs. The effect of air headspace, vent holes area and inlet airflow rate on the cooling efficiency was investigated.Experimental results revealed significant cooling heterogeneities among different AC positions, with the largest observed disparities being 1.8 h for half cooling time (HCT) and 3.7 h for seven-eight cooling time (SECT) in the current tray design. Incorporating vent holes into the current commercialized tray design demonstrated superior cooling performance, with 8% improvement of the overall average HCT. Analysis showed increasing the thickness of the air headspace above the AC increased 91% and 113% the overall average HCT and SECT, respectively. The research found that airflow distribution in a tray has a critical effect on the heat transfer between the AC walls and the surrounding air temperature. Thus, the packaging design is crucial in ensuring proper ventilation around the ACs.The alternative designs or operating under a lower airflow rate revealed a potential to cut down on energy use for ventilation. Specifically, when the airflow rate was reduced by one-quarter, there was a remarkable 94% decrease in energy usage. However, this benefit is counterbalanced by a 100% increase in the overall average HCT, which might adversely affect the product quality. Hence, optimizing the packaging design is essential to ensure the right balance between energy efficiency and product quality.The HCT exhibited a linear correlation with the external resistance, which is influenced by the airflow behavior, whatever the AC positions and tray designs.

Effects of Rodent Isolation on Plant Community Structure and Greenhouse Gas Emission in the Alpine Grassland of the Qinghai–Tibet Plateau

As one of the dominant species of the alpine grassland on the Qinghai–Tibet Plateau, the activities (e.g., gnawing, burrowing, and grass storage) of plateau pikas (Ochotona curzoniae) directly alter the plant community structure of the grassland ecosystem and affect livestock production and greenhouse gas emission. In order to investigate the effects of rodent isolation (RI) on plant community structure and greenhouse gas emission in the alpine grassland of the Qinghai–Tibet Plateau, we established plots of rodent isolation and rodent activity (i.e., the control sample (CK)) in the 14th village, Seni District, Nagqu City in May 2018. From July 2019 to September, the numbers, sizes, and total damaged area of effective holes; the height, coverage, and aboveground plant biomass; and the methane (CH4) and nitrous oxide (N2O) emissions of the alpine grassland were monitored by the quadrat survey method and static closed-chamber method. The results show that the invasion and tunneling of Ochotona curzoniae resulted in the destruction of alpine grassland measuring 0.064 m2 per square meter, while the rodent isolation plots showed that 97.9% of the alpine grassland remained unaltered; such unaffected land implies that the economic income of herdsmen could increase by 140 CNY hm−2. The rodent isolation plots also show that the height and proportion of grasses and sedges in the alpine grassland increased, while the proportion of poisonous weeds decreased. Moreover, the rodent isolation plots also showed a significantly increased coverage of aboveground biomass (p < 0.05), although species richness showed no significant effect based on the Shannon–Weiner, Simpson, and Pielou indices (p > 0.05). The soil uptake of CH4 and N2O was 204.99 ± 50.23 μg m−2 h−1 and 4.48 ± 1.02 μg m−2 h−1 in the rodent isolation plots, significantly higher by 465.75% and 3001.4% relative to the rodent activity plots, respectively (p < 0.05). Therefore, the establishment of rodent isolation areas can effectively alleviate the degree of damage to alpine grasslands in the short run and slow down the greenhouse gas emission rate to some extent. However, excessive rodent control may also have negative effects on grassland ecosystems, so more attention should be paid in future studies to determining the disturbance threshold of plateau pika in this area. These results provide theoretical guidance for rodent control, grassland protection, and ecological environment management on the Qinghai–Tibet Plateau.

Energetic processes and thermodynamic analysis of the spinning Kiselev black hole with cloud of strings

Here we study the impact of the string clouds, the quintessence dark energy and other spacetime parameters on the center-of-mass energy, Penrose-process and thermodynamic properties of a stationary black hole solution of the Einstein field equations. We observe that the three distinct horizons i.e the Cauchy horizon, the event horizon and the cosmological horizon exist when the spin parameter a of the black hole is less than its extremal value aE. Interestingly we see that the infinite redshift surface of the black hole is not much sensitive to the quintessence parameter γ. It is sensitive to the parameter a and it increases as the parameter a increases. Further, we notice that an increase in the string cloud parameters b, quintessence parameter γ and a make the radius of the ergosphere of the black hole larger. We also notice that a rise in the parameter a makes the innermost stable circular orbits (ISCO) smaller and for an increase in the parameter b and γ the ISCO becomes larger than that for the Kerr spacetime. For the center-of-mass energy of the spinning black hole with quintessence and cloud of strings we observe that it can be arbitrarily high only for the extremal case of the black hole for a specific range of values of the angular momentum of the colliding particles. We notice that the Penrose-process is more efficient for smaller values of the string cloud parameter b and the parameter γ has no significant impact on this process. Moreover we see that an increase in the parameters b, γ and a cause the Helmholtz free energy to increase and opposite is true for the temperature of this type of rotating black hole. We learn that the area and entropy of the black hole are also depend on the parameters b, γ and a, and their effect make the entropy smaller. Interestingly we find a range of the horizon radius for the thermodynamic stability of the black hole. To get more information about the thermodynamic quantities of the rotating black hole with quintessence and cloud of strings, we plot them for different ranges of the spacetime parameters.

Implementation of a new approach based on the functionally graded materials concept to improve the strength of laminated composites containing open‐hole

AbstractThe main objective of the present study is to implement a functionally graded materials (FGM) technique to reduce the hole effect in fiber reinforcement polymers. The tensile and fracture behaviors of conventional and FGM composites containing open holes have been investigated. Open‐hole specimens having different hole sizes have been fabricated using a hand lay‐up technique with different cross‐ply stacking sequences and various numbers of layers to study the open‐hole effect on their tensile strength. On the other hand, a three‐dimensional finite element analysis with the Hashin model was implemented to observe the failure modes along each layer. Experimental and numerical data revealed that the FGM technique enhanced the performance of specimens in the presence of a hole by increasing the fibers around the hole area. Furthermore, the [0/90/0°] sequence has more tensile strength than [0/90]s and [0°/90°/0°/90°/0°] sequences. It can be concluded that the bearing capacity of cross‐ply laminates is proportionally dependent on the ratio of the number of 0° layers to the number of 90° layers and inversely dependent on the specimen thickness.Highlights Dense fibers around the open hole improve its strength in laminated composite. The FGM concept has been successfully employed to improve open‐hole strength. The stacking sequence [0°/90°/0°] has better tensile strength than [0°/90°]s. FEA has successfully simulated the FGM concept around the open hole. The open‐hole failure occurred in the same direction as fiber orientation.

48‐4: Distinguished Paper: Backside Bonding for Extremely Narrow Bezel at the Bottom of Flexible Displays

We developed a novel method to minimize the bezel of flexible displays through backside bonding of a chip on film, resulting in the bezel width of less than 500 μm as compared to 1000 μm of conventional displays. The metal embedded in polyimide (MEP) layer is placed between the first and second polyimide (PI) substrates and connected to the metal lines of the backplane via the MEP contact (M‐CNT) hole. Subsequently, the nonconductive film (NCF) bonding and intense pulsed light sintering are performed using conductive ink. Conductive ink as the interconnect material capable of low‐temperature sintering is applied to avert thermal degradation and crack. At a high temperature (65 ℃) and humidity (90% relative humidity), the contact resistance was a drivable level for the display after 240 h. The normalized strain in the M‐CNT hole and MEP area were less than 0.4, indicating the absence of cracks during the NCF bonding. These results demonstrated that the backside bonding method was suitable for extremely narrow bezels of the nextgeneration flexible displays.

P‐64: Research on Displayable Scheme of Camera Under Panel Based on Automobile Display

CUP (Camera Under Panel) is applied to the automobile and can identify the driver's identity, monitor the driver's fatigue, attention, and monitor dangerous driving behaviors. The commonly used blind hole technology now leads to the inability to display the camera hole area. Therefore, we proposes a scheme for camera under panel applied to automobile, which is based on the Mini LED backlight structure design to achieve full screen display. At the same time, optical simulation analysis and related experiments were conducted to verify the feasibility of the scheme.

Blade retrofit design to reduce the noise of an axial flow fan by mitigating the tip leakage vortex

In the context of controlling axial fan aerodynamic noise, one effective approach involves the redesign of the blade. In the present study, a novel blade design was formulated for a specific model of axial flow fan, targeting the mitigation of the tip leakage vortex (TLV) and subsequent reduction of noise levels. The assessed noise-reduction blades have perforations drilled from the leading edge (LE) to the pressure surface (PS) of the blades. By impeding the tip leakage flow (TLF), these perforations effectively weaken the TLV. The three-dimensional non-constant flow field within the channel is computed employing the shear stress transport (SST) turbulence model. The aerodynamic noise prediction, which is based on the Lighthill’s acoustic analogy theory, shows that the designed blades can effectively reduce the aerodynamic noise of the axial fan. Specifically, enhancing the ratio of inlet area to outlet area of the ventilation holes leads to an improved noise reduction effect. Notably, for ratios of 0.44 and 1.06, the designed blades exhibit noise reductions of up to 3.3 dB(A) and 3.9 dB(A), respectively. Meanwhile, the static efficiency of these two fans is reduced by 0.50% and 0.26%, respectively. The study thus provides good theoretical support for the design of axial flow fans in the context of noise reduction.

Coarse-graining black holes out of equilibrium with boundary observables on time slice

In black hole thermodynamics, defining coarse-grained entropy for dynamical black holes has long been a challenge, and various proposals, such as generalized entropy, have been explored. Guided by the AdS/CFT, we introduce a new definition of coarse-grained entropy for a dynamical black hole in Lorentzian Einstein gravity. On each time slice, this entropy is defined as the horizon area of an auxiliary Euclidean black hole that shares the same mass, (angular) momenta, and asymptotic normalizable matter modes with the original Lorentzian solution. The entropy is shown to satisfy a generalized first law and, through holography, the second law as well. Furthermore, by applying this thermodynamics to several Vaidya models in AdS and flat spacetime, we discover a connection between the second law and the null energy condition.

Detection of gunshot residue by flash-pulse and long-pulse infrared thermography

Detection of gunshot residues (GSR) in a bullet hole area is one of the forensic investigations aiding in the reconstruction of crime scenes. Traditionally, chromogenic methods based on chemical exposure or microscopic/spectroscopic methods are used for this purpose. In this study, we explore the applicability of active excitation infrared thermography methods for GSR detection in the bullet hole area on fabric samples. A standard 9 mm full metal jacket ammunition with a nickel-plated shell and natural cotton fabric samples were used for experiments in this study. The applicability of active thermography methods based on two different light/heat excitation sources to detect the GSR was investigated. Flash-pulse and long-pulse thermography were compared through an experimental investigation. We evaluated the effectiveness of various thermographic data processing methods, including background subtraction, temperature derivative analysis, Fourier transform phase analysis, principal component analysis, and higher-order statistics for GSR evaluation. Our findings demonstrate that flash-pulse thermography and kurtosis analysis yield the highest contrast-to-noise ratio (CNR) and produce sharp, clear images of GSR, making it the optimal method for thermographic GSR detection. Our study indicates that even though the GSR particles are tiny, they can produce sufficient contrast to be detected by the thermographic methods if appropriate experimental and post-processing procedures are used. Thus, these methods could complement GSR detection as they are non-destructive and offer rapid inspection.

Coupled capture and photocatalysis of g-C3N4 based magnetic composites: Mechanism and disinfection activity against Staphylococcus aureus

The disinfection ability of g-C3N4 by photocatalysis is restricted, owing to its small surface area and rapid combination of holes (h+) and electrons (e−). Moreover, recycling of g-C3N4-based photocatalysts from aqueous solution is difficult, which increases the cost of application. In the present study, g-C3N4 was combined with magnetic biochar (MBC) by high temperature calcination to fabricate g-C3N4/MBC composites. The as-prepared g-C3N4/MBC composites acquired larger specific surface area, narrow bandgap, and broad-range of visible absorption capability. The g-C3N4/MBC composites showed good killing efficiency towards Staphylococcus aureus (S. aureus) under visible light irradiation. Efficient photocatalysis was achieved by the effective separation of e−/h+ within the g-C3N4/MBC composites. Moreover, the capture effect of MBC for S. aureus reduced the distance and increased the contact area between the g-C3N4/MBC composite and S. aureus. The g-C3N4/MBC-10 % showed notable stability and reusability over a broad pH range of 4–8 and in presence of different inorganic ions (Cl− and SO42−) and humic acid. After 5 cycles, the g-C3N4/MBC-10 % could still eliminate about 95 % of S. aureus cells. The g-C3N4/MBC-10 % was also highly effective in reducing the bacterial population in water samples taken from a nearby lake, thus showing considerable promise for use in water sterilization. In addition, g-C3N4/MBC composites were highly effective in eliminating the biofilm and inhibiting the growth of the new biofilm of S. aureus. The main active species in photocatalytic disinfection were determined, to be •OH, h+, and •O2−. This study would help to understand the capture and photocatalysis of g-C3N4 based composites for environmental applications.

Damage characteristics of rock induced by unloading in hole under true triaxial boundary stresses: Experimental study

In order to study the effect of unloading of underground rock excavation on the stability of surrounding rock, the true triaxial compression (TTC) and coupled true triaxial compression and in-hole loading-unloading tests (TTC-HU) were conducted on hollow cubic rock (100mm × 100mm × 100mm). The experimental results indicate that the compressive strengths of the specimens increase as confining pressure increases in the equal biaxial stressand increase with increasing intermediate principal stresses in the unequal biaxial stress. At low confining pressure (σ < 30 MPa), the internal stress at unloading damage in the hole of hollow cubic specimen increases with the increase of the three-directional boundary stresses. At high confining pressure (σ ⩾ 30 MPa), the specimen will not be damaged during the entire unloading process in the hole. The damage mode of the specimen is dominated by tensile damage. The shape of the holes in the specimens did not significant change, and hole wall of specimen have layered destruction along the circumference in low confining pressure. In high confining pressure, the hole area of the specimen undergoes significant deformation damage, forming a V-groove along the direction of the minimum principal stress, and the wall of the hole is completely peeled off. This study can reasonably predict the actual engineering damage patterns and guide the optimization of surrounding rock support.

A generalization of the Hawking black hole area theorem

Hawking’s black hole area theorem was proven using the null energy condition (NEC), a pointwise condition violated by quantum fields. The violation of the NEC is usually cited as the reason that black hole evaporation is allowed in the context of semiclassical gravity. Here we provide two generalizations of the classical black hole area theorem: first, a proof of the original theorem with an averaged condition, the weakest possible energy condition to prove the theorem using focusing of null geodesics. Second, a proof of an area-type result that allows for the shrinking of the black hole horizon but provides a bound on it. This bound can be translated to a bound on the black hole evaporation rate using a condition inspired from quantum energy inequalities. Finally, we show how our bound can be applied to two cases that violate classical energy conditions.

Backside bonding for extremely narrow bezel at the bottom of flexible displays

AbstractWe developed a novel method to minimize the bezel of flexible displays through backside bonding of a chip on film, resulting in the bezel width of less than 500 μm as compared to 1000 μm of conventional displays. The metal embedded in polyimide (MEP) layer is placed between the first and second polyimide (PI) substrates and connected to the metal lines of the backplane via the MEP contact (M‐CNT) hole. Subsequently, the nonconductive film (NCF) bonding and intense pulsed light sintering are performed using conductive ink. Conductive ink as the interconnect material capable of low‐temperature sintering is applied to avert thermal degradation and crack. At a high temperature (65°C) and humidity (90% relative humidity), the contact resistance was a drivable level for the display after 240 h. The normalized strain in the M‐CNT hole and MEP area were less than 0.4, indicating the absence of cracks during the NCF bonding. These results demonstrated that the backside bonding method was suitable for extremely narrow bezels of the next‐generation flexible displays.

Theoretical modeling of concrete friction-impact deterioration using water-borne sand abrasion experiment

To explore the influence of impact angle on concrete abrasion deterioration under water-borne sand, a theoretical model for friction-impact deterioration was developed. This model innovatively proposes the inhibition effect of the normal impact action on the tangential friction mass loss and the facilitation effect of the tangential friction action on the normal impact mass loss to rationally explain the effect of impact angle on concrete mass loss. Simultaneously, a water-borne sand accelerated abrasion experiment was conducted to initiate a comprehensive discussion on surface abrasion deterioration indicators, including mass loss, number of holes, aperture, hole area, and hole volume. In addition, the concrete abrasion mass loss rate was evaluated based on the friction-impact deterioration model combined with experimental data. Applying this model facilitates a reliable prediction of concrete's mass loss caused by abrasion. Consequently, this allows for a more accurate assurance of the safety of concrete structures exposed to abrasive conditions throughout their operational life. The results show that the mass loss per unit area, maximum aperture, hole area ratio, and hole volume exhibit a trend of first decreasing, then increasing and finally decreasing with the increase of impact angle. Under 15°, 60°, and 90°, 70 % of the mass loss per unit area of the concrete specimens occurred within the first 6 d of abrasion. When the angles were 30° and 45°, 50 % of the mass loss per unit area of the concrete specimens occurred in the 9–12 d abrasion. It has been revealed that 69° results in the most severe abrasion mass loss. The abrasion deterioration process of concrete can be divided into three primary stages, including surface mortar abrasion, prime aggregate-mortar abrasion, and continuous aggregate-mortar abrasion. Additionally, the friction-impact theoretical model was employed to simulate the abrasion of both single and multiple pier columns, and the simulations provided insights into the non-uniform mass loss rate distribution around the pier columns.

Failure Analysis of Cast Iron Housing Unit of Ucf-216 Ball Bearing Used in a Fully Automatic Concrete Building Block Machine

One of the most common problems faced by briquette machine users in the industry is the failure of the cast iron housing unit of the UCF-216 bearings, to which the main shaft of the briquette machine is attached. In this study, the failure mechanism of a cast iron housing unit of a UCF-216 bearing broken during operation in a briquette machine was analysed in order to develop a solution to the problem. Failure was occurring in the bolt hole areas of the housing unit. First of all, spectral analysis was performed and it was determined that the housing unit was grey cast iron. Then, the macrostructures of both unused and damaged housing units were examined. Some casting defects were detected in the bolt hole areas of the unused housing unit. It was also learned that during the assembly of the UCF-216 to the briquette machine, no torque meter was used while the bolts were tightened. In order to understand the effect of possible overtightening of the bolts, the system was modelled as a 3D solid. This model was exported to the finite element software and different bolt pretensions were applied considering the stresses created by the bolt tightening forces on the housing unit. As a result, it was understood that if the ratio of the stress caused by the axial bolt tightening force in the UCF-216 bearing unit to the yield stress of the UCF-216 housing unit is above 50%, fatigue failure will occur.

Hydrodynamic Modeling and Comprehensive Assessment of Pier Scour Depth and Rate Induced by Wood Debris Accumulation

This study mainly investigates the impact of debris accumulation on scour depth and scour hole characteristics around bridge piers. Through controlled experiments with uniform sand bed material, the influence of various debris shapes (high wedge, low wedge, triangle yield, rectangular, triangle bow, and half-cylinder), upstream debris length, downstream debris extension, and debris thickness on scour depth and scour hole area and volume around the cylindrical pier were analyzed. The findings revealed that the shape and location of debris in the water column upstream of piers are key factors that determine the depth of scour, with high wedge shapes inducing the deepest scour and potentially the largest scour hole, particularly when positioned close to the pier and fully submerged. Scenarios in which triangle bow debris was submerged at full depth upstream of the pier closely resembled situations devoid of debris. Conversely, debris extension downstream of the pier was found to reduce local scour depth while concurrently enlarging the dimensions of the scour hole. The existing scour prediction equations tend to overestimate scour depth in scenarios involving debris, particularly when applying effective and equivalent pier width. This discrepancy arises because these equations were originally developed to predict scour depth around piers in the absence of debris. In response, a refined model for predicting scour induced by debris was proposed, integrating factors such as upstream debris length, downstream extension, obstruction percentage, and debris shape factor. This model demonstrated strong agreement with experimental data within the scope of this study and underwent further validation using additional experimental datasets from other research endeavors. In conclusion, this experimental study advances the comprehension of scour processes around cylindrical bridge piers, providing valuable insights into the role of debris characteristics and positioning.

An Investigation into the Lateral Bearing Performance of a Single Pile Embedded at a Three-Dimensional Asymmetric Local Scour Site Using the Modified Strain Wedge Model

The scouring effect is widely acknowledged as a primary contributor to the weakening in the bearing performance of offshore piles; it often results in asymmetric scour patterns around the pile. To meticulously examine the impact of three-dimensional asymmetric local scour on the lateral bearing performance of a single pile, the Boussinesq solution is employed to determine the effective stress within the soil encompassing the pile, considering the presence of a three-dimensional asymmetric local scour hole. Utilizing the strain wedge model, the calculation method for the lateral bearing performance of a single pile under the condition of three-dimensional asymmetric local scour is established. The validity of this approach is established, and parameter analysis unveils the effect of varying sizes of three-dimensional asymmetric scour holes on the mechanical properties and displacement performance of a single pile. The analysis reveals that, as scouring dimensions around the pile escalate, the impact of scouring on single-pile lateral displacement and internal forces intensifies, leading to a decrease in the lateral bearing performance of a single pile. At a constant scour depth, the bottom area of the upstream scour hole significantly influences the displacement performance of a single pile. When the bottom length Swb1 of the upstream scour hole grows by 1 time, 4 times, and 8 times, the lateral displacement of a single pile at a buried depth of 6 m is augmented by approximately 0.41%, 1.65%, and 2.06%, respectively. The simplified model obtained via the modified strain wedge model and Boussinesq solution can provide a theoretical basis for the preliminary design of a single pile under asymmetric scour hole conditions.

On the Origin of the Sudden Heliospheric Open Magnetic Flux Enhancement During the 2014 Pole Reversal

Coronal holes are recognized as the primary sources of heliospheric open magnetic flux (OMF). However, a noticeable gap exists between in situ measured OMF and that derived from remote-sensing observations of the Sun. In this study, we investigate the OMF evolution and its connection to solar structures throughout 2014, with special emphasis on the period from September to October, where a sudden and significant OMF increase was reported. By deriving the OMF evolution at 1 au, modeling it at the source surface, and analyzing solar photospheric data, we provide a comprehensive analysis of the observed phenomenon. First, we establish a strong correlation between the OMF increase and the solar magnetic field derived from a potential-field source-surface model (cc Pearson = 0.94). Moreover, we find a good correlation between the OMF and the open flux derived from solar coronal holes (cc Pearson = 0.88), although the coronal holes only contain 14%–32% of the Sun’s total open flux. However, we note that while the OMF evolution correlates with coronal hole open flux, there is no correlation with the coronal hole area evolution (cc Pearson = 0.0). The temporal increase in OMF correlates with the vanishing remnant magnetic field at the southern pole, caused by poleward flux circulations from the decay of numerous active regions months earlier. Additionally, our analysis suggests a potential link between the OMF enhancement and the concurrent emergence of the largest active region in solar cycle 24. In conclusion, our study provides insights into the strong increase in OMF observed during 2014 September–October.

Investigation of the total pressure gain in rotating detonation combustors with dilution holes

An investigation of the total pressure gain (TPG) in rotating detonation combustors (RDCs) with dilution holes is conducted by the experimental method in this study. The effects of pressure ratios (PR = 4.2–7.2) and equivalence ratios (ER = 0.5–1.5) on the total pressure gain are analyzed in four models, i.e., models A–D, of different throat areas A3.1 and dilution hole area A3.5. When the PR is small, the lowest ER causes the highest TPG, and when the PR is high, the highest ER leads to the highest TPG in Model A. While in models B–D, as ER increases, the TPG increases gradually in all the cases. Comparing the level of TPG between the four models, it is found that the increment of A3.1 and A3.5 results in the enhancement of the TPG. The present study's TPG shows superiority when compared with that of traditional RDC, which indicates that the RDC with dilution holes is more promising for achieving positive TPG in specific configurations. An empirical model considering the throat area A3.1, dilution hole area A3.5, outlet area A8, and heat (released by the fuel combustion) release rate Qv is proposed to better predict the performance of different RDC configurations. Positive total pressure gain is inferred to be promisingly attained at a high A3.1/A8, low A8/A3.5, and a high Qv. Total pressure measured by total pressure rake is verified by comparing with the data calculated by Mach-corrected-static-pressure and mass flow function methods, with relative errors in ±4% and ±15%, respectively.

Study on load characteristics and structural impact response propagation law of cabin internal explosion

Aiming at the problem that the distribution of explosion load in the cabin and the propagation law of structural impact response was unclear, this paper established the numerical calculation model of explosion in a closed cabin by ALE (Arbitrary Lagrangian Eulerian) method. There was an apparent convergence of shock waves at the cabin's corners, and the pressure relief hole's area and its position significantly affected the peak of quasi-static pressure. The peak acceleration of the deck structure decreased exponentially as the distance from the location of charge increased. Peak acceleration decreased by approximately 50% for each bulkhead crossing. There was a “paper window effect” during the cabin interior explosion on the whole ship. It meant there was a limit to the value for the energy generated by the explosion to be transmitted along the frame structure. When the charge was 150 kg, it reached the limit of the energy transferred by the structure in this paper. The response of the distant structure did not change significantly with the increase in the charge quality. The research revealed the impact response propagation mechanism in the structure and provided a reference for designing protective structures.