Rectangular Gap Research Articles

MODIFIKASI DINDING BUBU LIPAT UNTUK MELOLOSKAN RAJUNGAN YANG BELUM LAYAK TANGKAP

Increasing of fishing pressure poses a serious threat to the sustainability of blue swimminng crab resources. Trap design modifications are needed to improve size selectivity and to release under size crabs. This study aimed to determine the type of wall modification of collapsible trap that is effective in excluding under size blue swimming crab. Laboratory observations were conducted using four escape vents treatments and three different mesh sizes. The escape gap used are rectangular, square, circular and oval respectively. Moreover, the mesh sizes used are 2.0 inches, 2.5 inches and 3.0 inches. Descriptive analysis and scoring were used to determine the most effective type of wall trap modification to be used in the blue swimming crab fishing. The results showed that the rectangular escape gap has better effectiveness than other shapes with the percentage of crabs that pass through at 86.7%. The wall modification using a 3.0-inch mesh size had better performance than the other modification types with a total score of 19. Collapsible trap with a 3.0-inch mesh wall was able to escape 86.7% of the crabs with an escape time of only 11.2 seconds and an average escaped crab carapace width of 78 mm. Keywords: Collapsible trap, escape gap, environmentaly-frendly fisheries, mesh size of trap wall

Finite Element Analysis and Design of a Flexible Thermoelectric Generator with a Rhombus Gap Structure.

Flexible thermoelectric generators (f-TEGs) offer an opportunity to realize wearable, self-powered electronic devices. A typical f-TEG consists of flexible electrodes and rigid thermoelectric (TE) legs in a flexible package. In the realm of f-TEGs utilizing flexible electrodes and TE cuboids, our unwavering objective lies in the attainment of enhanced flexibility and elevated energy conversion efficiency. In this paper, we employ a quasi-three-dimensional thermal model to design an f-TEG with a rhombus gap structure (E/A-RhTEG) with its optimized performance validated by simulation and experiment. Additionally, the lateral and vertical thermal resistances are introduced to further explain the optimizing principle in the f-TEG's output performance. Compared with the conventional TEG with a rectangular air gap structure (E/A-ReTEG), E/A-RhTEG demonstrates improved energy conversion efficiency to some extent. Simulation results indicate that the output power and energy conversion efficiency of a 25-np-pair E/A-RhTEG at a 30 K temperature gradient reach 8.45 mW and 2.55%, which represent a performance improvement of 3.09 and 6.28%, respectively, compared to E/A-ReTEG. To further elucidate the optimization principle in the performance of f-TEGs, additional considerations are given to the lateral and vertical resistances. In this study, E/A-RhTEG comprising 25 np pairs is fabricated utilizing TE cuboids. Experimental findings indicate that E/A-RhTEG exhibits a voltage output of 127.07 mV when subjected to a temperature difference of 30 K, which demonstrates a performance enhancement of 4.06% compared to E/A-ReTEG. Furthermore, this study also demonstrates its implementation when wrapped around a curved surface and successfully achieves a self-powered device system after device performance optimization.

Selectivity in snow crab (Chionoecetes opilio) pot fishery: Effect of escape gap shape and size for conservation of fishery resources

Conical pots are commonly used fishing gear for capturing snow crab (Chionoecetes opilio). In these fisheries, optimal snow crab size selection is important for reducing unintended mortality of undersized individuals aiming at conserving fisheries resources and reducing sorting time onboard fishing vessels. Size selection in snow crab pot fisheries commonly takes place through pot netting meshes during deployment. The diamond mesh netting has varying opening angles affecting retention of snow crab of different sizes, and often large proportions of catches consist of undersized crab challenging natural resource conservation. Some commercial snow crab fisheries use rigid escape gaps in addition to mesh selection to improve size selectivity. In this study, we predict the size selection potential of escape gaps with different shape and size and investigated whether such additional size selection mechanism can have a potential to improve selectivity compared to mesh selection. Results showed that circular escape gaps have potential to provide sharper size selection compared to netting meshes and thus could be used to limit the capture of undersized snow crab which is relevant for management and conservation of snow crab resources. However, a similar positive effect cannot be obtained to the same extent with elliptical and rectangular escape gaps.

Machine learning assisted dual port metasurface loaded MIMO antenna with linearly polarized to circularly polarized conversion features for n257 band of 5G mm‐wave applications

SummaryIn this communication, a dual port printed multi‐input and multi‐output (MIMO) antenna with high isolation of dimension 12 × 8.5 × 0.8 mm3 is designed, analyzed, and investigated for 28‐GHz 5G mm‐wave applications. The metasurface layer is suspended over the MIMO antenna to convert the linearly polarized (LP) wave to a circularly polarized (CP) wave. The unit cell of the metasurface consists of a square‐shaped conducting strip with one side of diagonal points interconnected. The conducting strip and rectangular gap between the strips etched on the substrate are capable of generating the π/2 phase shifted electric field components (Ex and Ey) resulting in polarization conversion from LP to CP. The machine learning concept is used to characterize the dimensional configuration of the antenna to achieve the optimum throughput. The MIMO diversity performance parameters and antenna essential results are validated by the measured counterparts.

Improved Clinical Outcomes With Dynamic, Force-Controlled, Gap-Balancing in Posterior-Stabilized Total Knee Arthroplasty

BackgroundOptimal soft-tissue management in total knee arthroplasty (TKA) may reduce symptomatic instability. We hypothesized that TKA outcomes using a computer-assisted dynamic ligament balancer that acquires medial and lateral gap sizes throughout the motion arc would show improved Knee Society Scores (KSS) compared to TKAs done with a traditional tensioner at 0 and 90°. We also sought to quantify the degree to which the planned femoral rotation chosen to optimize medio-lateral balance throughout the arc of motion deviated from the femoral rotation needed to achieve a rectangular flexion gap at 90° alone. MethodsBaseline demographics, clinical outcomes, KSSs, and femoral rotations were compared in 100 consecutive, computer-assisted TKAs done with the balancer (balancer group) to the immediately prior 100 consecutive computer-assisted TKAs done without the balancer (control group). Minimum follow-up was 13 months and all patients had osteoarthritis. Mean knee motion did not differ preoperatively (110.1 ± 13.6° balancer, 110.4 ± 12.5° control, P = .44) or postoperatively (119.1 ± 10.3° balancer, 118.8 ± 10.9° control, P = .42). Tourniquet times did not differ (93.1 ± 13.0 minutes balancer, 90.7 ± 13.0 minutes control, P = .13). Postoperative length of stay differed (40.2 ± 20.9 hours balancer, 49.0 ± 18.3 hours control, P = .0009). There were 14 readmissions (7 balancer, 7 control), 11 adverse events (4 balancer, 7 control), and 3 manipulations (1 balancer, 2 control). The cohorts were compared using Student’s t-tests, Shapiro-Wilk normalities, Wilcoxon rank-sums, and multivariable logistic regression analyses. ResultsPostoperative KSS improvements were higher in the balancer group (P < .0001). In multivariable regression analyses, the balancer group experienced 7 ± 2 point improvement in KSS Knee scores (P < .0001) and 4 ± 2 point improvement in KSS Function scores (P = .040) compared to the control group. ConclusionsThe statistically and clinically significant improvements in postoperative KSS demonstrated in the balancer cohort are likely driven by improved stability throughout the motion arc. Further study is warranted to evaluate replicability by non-design surgeons.

Effects of Severe Varus Deformity on Soft Tissue Balancing in Total Knee Arthroplasty.

This study aimed to establish the effect of severe varus deformity on soft tissue balance in total knee arthroplasty (TKA), which is not yet well established. We retrospectively enrolled 205 patients (270 knees) who underwent primary TKA using the measured resection technique. Four intraoperatively measured TKA gaps and gap differences were compared between the severe varus deformity group (Hip-knee-ankle [HKA] varus angle ≥ 10°) and the mild varus deformity group (HKA varus angle < 10°). Pearson’s correlation analysis and multiple linear regression analysis were used to investigate the factors affecting flexion and extension gap differences (FGD and EGD). A receiver operating characteristic curve was applied to assess the cut-off value of the HKA varus angle to discriminate the rectangular gap. The FGD (1.42 ± 1.35 mm vs. 1.05 ± 1.16 mm, p = 0.019) and the EGD (1.45 ± 1.32 mm vs. 0.97 ± 1.53 mm, p = 0.006) were significantly larger in severe varus deformity group than in mild varus deformity group. The HKA varus angle was positively correlated with both FGD (r = 0.264, p < 0.001) and EGD (r = 0.319, p < 0.001) and was an influencing factor for FGD (β = 0.232, p = 0.040) and EGD (β = 0.229, p = 0.037). A preoperative HKA angle of 12.4° was selected as the cutoff value to discriminate between rectangular and trapezoidal gaps. Thus, the severity of varus deformity (HKA varus angle) was found to be a significant factor affecting the mediolateral gap difference in TKA. When performing TKA in a knee with an HKA varus angle ≥ 12.4°, a trapezoidal gap is more likely to be expected. Level of evidence III, case−control study.

Resonance Control of VO2 Thin-Film-Based THz Double-Split Rectangular Metamaterial According to Aspect Ratio

The resonance characteristics of a double-split rectangular metamaterial based on a vanadium dioxide (VO2) thin film were controlled according to the aspect ratio of the rectangle in the terahertz (THz) frequency region. The VO2 thin film line was etched between the double-split rectangular gaps so that the resonance band could be switched by varying the characteristics of the VO2 thin film. When the VO2 thin film is in an insulator state, the rectangle is separated and resonates individually; thus, it resonates in the high-frequency band. When the VO2 thin film changes from an insulator to a conductor with a change in the temperature, the divided rectangles are electrically connected to operate as a single resonator, and the resonant frequency shifts to a low-frequency band. Varying the aspect ratio of the rectangle changes the resonant frequency and resonance strength of the double-split rectangular metamaterial. If the aspect ratio is increased by fixing the width of the unit cell of the metamaterial and adjusting the height, the resonant frequency is lowered in all situations, regardless of the state of the VO2 thin film and the polarization of the incident THz wave. The resonant frequency and resonance strength of the double-split rectangular metamaterial proposed in this paper could be controlled stably through a change in only the aspect ratio, not the overall unit cell size. The proposed double-split rectangular metamaterial based on an etched VO2 thin film is expected to be essential for THz tag, sensing, and wireless communication applications.

Numerical modelling of the effect of appendages on turbulent mixing in connected nuclear fuel subchannels

The effects of appendages on flow characteristics and scalar mixing in gap-connected twin-subchannel geometries has been investigated. Mixing is assessed for a symmetric, rectangular compound channel geometry connected by a single rectangular gap using computational fluid dynamics (CFD). Detailed numerical models, characterizing the full test section from a reference experimental study, are generated and validated against measurements. Time varying details of the gap induced periodic structures and appendage induced vortices are captured through calculations in an unsteady Reynolds Averaged Navier-Stokes (URANS) framework coupled with the Spalart-Allmaras (SA) turbulence model closing the RANS equations. Companion simulations are performed at each of two Reynolds numbers (2690 and 7500), one with and one without a gap-centered appendage. The appendage effects on flow characteristics and mixing are isolated through comparison of the associated simulations.In the absence of appendages, fluid exchange between subchannels is dominated by quasi-periodic flow pulsations through the gap (gap vortex streets) formed due to flow instability in the near gap region. Without a gap-centered appendage, the magnitude, frequency, and structure length of the gap pulsations are well predicted by the model at both Reynolds numbers. Mixing between subchannels is reasonably well predicted for Re = 2690 (within approximately 17% of the experimental value). The model fails to capture the measured increase in scalar transfer through the gap with increased Reynolds number, underpredicting scalar mixing by 55% at Re = 7500. An argument is presented that the use of an isotropic turbulence model in the subchannels (SA), which precludes the development of subchannel secondary flows, is the source of the discrepancy between modelled and measured mixing at Re = 7500.Appendages, such as those introduced by end plates or bearing pads in CANDU fuel bundles, augment the exchange process between subchannels. With an appendage representative of a CANDU fuel bundle end plate web introduced into the gap region, cross flow velocity and frequency are predicted to increase immediately downstream of the appendage due to flow diversion and vortex shedding. The higher local frequency is shown to be consistent with the vortex shedding frequency calculated for a stationary rectangular cylinder at the gap conditions. Further downstream, gap induced instabilities begin to re-establish as the dominant contributor to cross flow pulsations although they are not fully recovered by the test section exit. Mixing is enhanced by the appendage with increasing Reynolds number for the conditions examined.

Tri-band MIMO antenna design based on characteristic modes manipulation

Several MIMO antennas based on the theory of characteristic modes have been proposed, but few of them introduce systematic design methods for microstrip MIMO antenna to obtain three frequency bands and as well as to reduce mutual coupling between the MIMO units. In this paper, a tri-band MIMO antenna is designed under the guidance of characteristic mode analysis. Firstly, the characteristic modes of the basic rectangular microstrip antenna are adjusted by loading rectangular spiral shaped stub and L-shaped slot at its proper positions to form a tri-band antenna unit. Next, based on the analysis of Modal significance and modal current distributions, the mode causing mutual coupling of the initial two-port MIMO antenna is determined, and then the meandering neutralization line connecting two adjacent edges and the rectangular gap in the middle of the common ground plane are designed as decoupling structures, which improve the isolation to more than 18 dB between two units with a distance of only 7.4 mm. Finally, the measured results prove the correctness and feasibility of the proposed systematic design process for the MIMO antenna, in terms of its compact size 32 mm ×26 mm, envelope correlation coefficient (ECC) less than 0.35, peak gain greater than 1.26 dBi and radiation efficiency greater than 76% in the three desired frequency bands (2.35–2.5 GHz, 3.25–3.85 GHz, and 4.4–6.2 GHz).

Investigation of the effects of central rectangular gap located in the adhesive layer on failure load and joint stiffness

Investigation of the effects of central rectangular gap located in the adhesive layer on failure load and joint stiffness

Disparity among recommended and adopted escape-gap designs and their utility for improving selection in an Australian portunid trap fishery

Over the past decade, most efforts at improving the selectivity of commercial, baited traps targeting the giant mud crab, Scylla serrata in south-eastern Australia have focused on testing rectangular escape gaps (46 mm high × 90–120 mm wide) in spatially and temporally restricted manipulative experiments, followed by some promotion among local fishers. Anecdotal data imply wider adoption of escape gaps throughout unassessed regions of the fishery, but there are no data on escape-gap designs, or if performances correspond to predictions from isolated experiments. This deficit was addressed here via a fishery-wide, observer-based assessment. During two fishing seasons, six observers sampled catches from seven estuaries responsible for 80% of the total S. serrata harvest. Most fishers used collapsible netted cylindrical traps (83% of traps and made from 50–55 mm stretched mesh opening); among which ~10% were fitted with one rectangular escape gap, while 37% had one or two circular escape gaps (85–90 mm diameter). Compared to traps with no escape gaps, those with rectangular escape gaps (46 × 120 mm) reduced the numbers of undersized S. serrata by 92% (similar to observations during previous manipulative experiments); but those with circular escape gaps did not reduce any unwanted catches. Rather, traps with circular escape gaps caught more legal-sized S. serrata, which was attributed to possible species-specific behaviours in the traps and less egress through funnel entrances. This result potentially contributed towards fisher opinions of circular escape-gap success (given they want to maximize desirable catches) and facilitated their wider adoption. The data reiterate ongoing fishery assessments are essential to understand the performances of evolving/devolving gear modifications and ensure intended stakeholder and resource management expectations are realized.

Investigation of Leaky-Wave Antenna With Stable Wide Beam-Scanning Characteristic

In this article, a compact magnetic dipole (MD) composite right-/left-handed transmission line (CRLH-TL) leaky-wave antenna (LWA) is proposed, which is periodically loaded with rectangular gaps and short stubs. Then, in light of the dielectric resonator with a high dielectric constant, low loss tangent, and good radiation performance, we further add an alumina ceramic block (ACB) to stack on the gap in each CRLH-TL LWA unit cell for forming the MD, and thus, wide beam-scanning range and compactness are achieved. To validate this design, a traditional uniform CRLH-TL LWA is investigated in detail. The results of S-parameters, electrical field distribution, and radiation properties illuminate the effects of introducing the ACB, such as impendence matching improvement and high radiation efficiency. Furthermore, to verify the flexible control of the balanced condition and the attenuation constant by changing the microstrip gap width and the ACB thickness predicted in the circuit model analysis, a nonuniform CRLH-TL LWA with quasi-constant amplitude is fabricated. Experimental results demonstrate a higher antenna gain and the stability of wide beam-scanning range under the condition of a compact design.

Self-aligned Technique for Tibial Component Placement in Total Knee Arthroplasty Lessening Rotational Malalignment in Measured Resection and Gap-Balancing Techniques.

Femorotibial rotational mismatch can occur when there is a rotational malalignment in either the tibial or femoral component. Self-aligned technique was proposed for orienting the tibial component in relation to the femoral prosthesis to reduce rotational malalignment between components. Therefore, we aimed to compare the rotational angle of the femoral and tibial components, as well as the femorotibial rotational mismatch, between the measured resection (MR) and gap-balancing (GB) techniques when combined with a self-aligned technique. We conducted a nonrandomized, experimental study with 50 patients in each group. The femoral rotation was set to 3° external rotation relative to the posterior condylar axis in the MR group, whereas the femur was resected to obtain an optimal rectangular flexion gap in the GB group. The self-aligned method was used to set the tibial rotation in both groups. Femoral and tibial rotational alignments were evaluated compared to a surgical transepicondylar axis of the femur using computed tomography. Rotational mismatch was defined as a difference between the femoral and tibial rotational alignments. A positive value indicated that the component was externally rotated relative to the reference line. The femoral component of the GB group was more externally rotated than that of the MR group (1.52° ± 1.31° vs 0.28° ± 1.16°, p < 0.001). However, the tibial rotational angle was not statistically significantly different between the MR and GB groups (1.28° ± 3.17° vs. 1.86° ± 2.81°, p = 0.220), and the rotational mismatch was 1.00° ± 3.28° and 0.34° ± 2.71°, respectively (p = 0.306). Although the femoral component of the GB group had a greater degree of external rotation than that of the MR group, the use of a self-aligned technique for tibial component placement resulted in no significant difference in tibial rotational alignment or rotational mismatch. This technique helps align the tibial component with the femoral component and lessen the degree of rotational malalignment in both the MR and GB techniques.

Is Flexion Gap Rectangular in Native Indian Knees? Results of an MRI Study.

The purpose of this study was to evaluate the flexion-gap of the native knees in the normal population and to assess any gender-specific variations in the flexion gap of the knees. A total of 50 normal asymptomatic volunteers with normal knee radiographs were selected for MRI of the knee. The left knee was scanned in an open MRI using a T1-weighted sequence. Imaging was performed in neutral, passive varus and valgus stress at 90° of knee flexion by placing custom-made blocks on a special board consecutively below the distal part of the leg. The study population consisted of 26 males and 24 females with a mean age of 25.77years. Under varus stress, the mean lateral flexion gap increased to 9.28 ± 1.53mm and under valgus stress, the mean medial flexion gap increased to 2.75 ± 1.22mm from neutral. The increase in the flexion gap on the lateral side was 5.28 ± 1.79mm, which was significantly higher compared to that on the medial side. In gender-specific analysis, the mean lateral flexion gap was 10.21mm in females and 8.46mm in males under varus stress. The findings of the study indicate that the lateral soft tissues are more lax compared to the medial soft tissue structures and this laxity is higher in females as compared to males. The study provides evidence of the existing physiological variations of these soft tissue structures resulting in a trapezoidal flexion gap in the native knees rather than the recommended rectangular gap.

Analysis of various mathematical models of turbulence when calculating the gas dynamics in a classifier with coaxially arranged pipes

This scientific article deals with the problem of choosing the mathematical model for calculating the gas dynamics in a classifier with coaxially arranged pipes. Various mathematical models were analyzed in ANSYS Fluent software package. Laminar, Spalart-Allmaras, k-ω, RSM and Transition SST were considered as mathematical models. The influence of number of cells in the calculation grid on the pressure loss change in the classifier for various mathematical models was also analyzed. The results of study showed that the pressure loss in the classifier with coaxially arranged pipes is not more than 395 Pa at the inlet gas flow rate of 10 m/s. Among the considered models i.e. laminar, Spalart-Allmaras, k-ω, RSM and Transition SST, the most adequate one is Transition SST model. When changing the number of cells in the calculation grid from 1241551 to 3159388 for this model, the deviation of pressure loss in the classifier was 0.43%. The article includes an equation for the dependence of pressure loss in the classifier on the inlet rate. The distribution of gas flow rate over various sections of rectangular gaps is shown.

Miniaturized Wideband Planar Antenna Using Interembedded Metasurface Structure

One kind of interembedded metasurface (MS) structure is proposed and applied to realize miniaturized wideband MS antennas (MSA). Different from conventional MSA, the proposed interembedded MSs are formed by etching slots on the radiating patch with various sawtooth schemes rather than rectangular gaps. Consequently, the resonance frequency of MSA can be decreased due to introducing those interdigital-like capacitances, while obvious miniaturization can be realized accordingly. By optimizing the parameters of the sawtooth radiating slots, a miniaturized antenna using cross-shaped interembedded MS is proposed, achieving an impedance bandwidth of 35.08% and a high gain of about 8.25 dBi with a compact overall size of 0.66λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.66λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> . Moreover, one further miniaturized antenna using modified cross-shaped interembedded MS is also presented, realizing a larger impedance bandwidth of 41.35% and a high gain of about 6.62 dBi with a smaller aperture of 0.48λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.48λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> . Compared with conventional MSA, 42% overall size reduction and larger bandwidth can be obtained. The design approach may provide a feasible solution to realize compact MSAs with the unique advantages of large bandwidth, low profile, low cost, and easy fabrication. Due to above good features, the proposed antenna can be a promising candidate for applications in modern wideband wireless communication systems.

Axial transonic compressor performance enhancement with circumferential grooves

Abstract. Casing treatment has been broadly used as a prudent passive flow control technique to improve the stall margin with a small drop in efficiency. The effect of grooves in certain details is overlooked however, different grooves shape (angels and location) has a remarkable effect on the controlling impact. In the current research work, an investigation on the effect of fillet and chamfer corners of rectangular circumferential grooves with various tip gap height on the performance of casing treatment is carried out with the help of CFD simulation. The performance of different models of grooves with various tip gap height on NASA rotor 37 is investigated by discretizing 3D RANS equations based on finite volume technique. Rectangular circumferential grooves casing treatment (CGCT) profile and smooth wall casing performances are evaluated. Moreover, the adiabatic efficiencies and the stall margins of smooth wall casing, rectangular grooves and rectangular grooves with fillet and chamfer corners are compared to assess the impacts of profiles of grooves on the stability and performance of axial flow compressor with different tip gaps. The stall margin of models 1–6 increased by 4.39 %, 2.52 %, 2.16 %, 1.75 %, 1.69 % and 2.06 % respectively. While the adiabatic efficiency of the models 1–6 decreased by 0.9 %, 1.01 %, 1.08 %, 1.12 %, 1.22 % and 1.16 % respectively.

A new type of the air‐filled substrate integrated gap waveguide resonator

This article presents the design and analysis of an air-filled substrate integrated gap waveguide (ASIGW) resonator. The electromagnetic field of each resonant mode in the resonator is studied by theoretical modeling and EM simulation. Besides, the relationship between the dimensions and Qu is analyzed and the Qu of the resonator can be as high as 2080 at Ku band. Compared with conventional rectangular waveguide resonator and gap waveguide (GW) resonator, the proposed ASIGW resonator can be fabricated more easily. Compared with the substrate integrated waveguide resonator, the ASIGW resonator is more tolerant with dimensional errors and with less degenerate modes. As an example, a fifth-order band-pass filter based on the ASIGW resonators is presented to verify the previous conclusions.

Study on the Influence of Air Tightness of the Building Envelope on Indoor Particle Concentration

In order to grasp the building palisade structure tightness of indoor particulate matter mass concentration based on the particle penetration mechanism and settlement characteristics, this article analyzes the measurements of two different types of building air tightness of a Shenyang university office building in terms of indoor and outdoor particulate matter mass concentration levels from 2016-1-09 to 1-22, 2016-7-18 to 8-03, and 2017-2-28 to 3-13. The building outside the closed window that had no indoor source condition, the indoor office building and outdoor particle mass concentration, and the aperture size and shape of the envelope were analyzed to carry on the numerical simulation research by Fluent software, which was then analyzed; the results reveal that the measuring point of the I/O ratio is less than point B of the I/O ratio, measurement points of A linear regression fitting degree is lower than the fit of the measuring point B, and the causes for the measuring point A tightness (level 8) is superior to the measuring point B (level 4). When the gap height h is greater than 0.5 mm, the penetration rate of particles within the range of 0.25–2.5 μm particle size is close to 1. In different gap depths, the penetration rate of particles within the range of 0.1–1 μm particle size was close to 1. In diverse pressure difference, the 0.25–2.5 μm particles within the scope of penetration rate P is close to 1, the gap on both sides of the differential value ΔP; the greater the particle, the higher penetration rate. The larger the right-angle number of gap n, the lower the penetration rate of particles. The L-shaped gap and U-shaped gap have significantly better barrier effects in larger and smaller particles than the rectangular gap. The research results in this paper can help people understand and effectively control the influence of outdoor particles on the indoor air quality and provide reference data for the prediction of indoor particle mass concentration in buildings, which has theoretical basis and practical significance.

Experimental study of moist air flow in the gap between the aircraft\u2019s fuselage and its cabin wall

We carried out an experimental study on the moisture transfer and the heat transport in warm and humid air flows between the cabin lining and the fuselage skin. The measurements were performed in a rectangular gap channel, representing the space between fuselage and cabin wall. Long-term measurements were performed for three configurations: without insulation, with fibreglass blanket and with melamine resin foam blanket. To simulate realistic flight conditions in a laboratory setup, we applied a concept of scaling. This concept is intended to guarantee similitude between the real flight conditions and the laboratory experiment. The results reveal that without insulation, the moisture transfer rate is much higher compared to the configurations with insulation blankets. With insulation, most of the water evaporates during ground conditions and just a small amount is entrapped in the insulation. Without insulation, just a small part of the frozen water evaporates on the ground. When comparing the two insulation blankets, it is found that they both have a similar heat transmittance coefficient. However, the condensation rate of the water and the resulting accumulation of water are significant, higher for the fibreglass blanket.