Effect Of Cross-sectional Area Research Articles

Explore the influence of fracture void space geometry on seepage: The effect of cross-sectional area and the blockage of contact area

The cross section of a fracture along the streamwise direction determines the water-passing capacity of the fracture. The seepage fields in four fracture models with different contact conditions are analyzed and investigated via computational fluid dynamics simulations. The main results are as follows: (1) a kind of low-velocity region is formed under small local aperture conditions; (2) the blocking degree of the contact area to the fracture seepage depends on the local flow channels compressed by it (flow angle and local aperture); (3) on a cross section, the interference of the contact area and roughness on the fluid flow make the average flow velocity (Uavg) greater than its streamwise component (uavg) except for seepage inlet, which increases with the decrease in the average mechanical aperture and the expansion of the contact area [C = 17.90%, compared to lower C, the whole average flow velocity (1.88 m/s) is the maximum]; (4) there may be an upward trend of pressure along the streamwise direction: where the cross-sectional area increases, the additional kinetic energy generated by the reduced flow velocity will be converted into pressure potential energy if it is not fully consumed by the viscous force; (5) along the streamwise direction, there is a linear correlation between the change rate in uavg (∂uavg/∂x) and that of average pressure on a cross section (∂P/∂x), which is affected by the interference of the contact area and roughness (R2 = 0.25 at C = 17.90%), a conceptual model derived from this linear correlation can describe the relation between the hydraulic characteristics of a fracture and streamwise cross section.

Exploration of cassava plant xylem for water treatment: preparation, characterization and filtration capability.

Flood is among the natural disasters that commonly happened in Malaysia every year. During the flood, victims faced clean water shortages and deterioration of the environment resulting in long waiting times for aid to access. Hence, affordable and efficient filters are needed to supply clean water in the affected areas. Application of xylem tissue inside plant stem has the potential as a filter for water filtration. This research focuses on xylem tissue in Malaysian tropical plants from cassava stem. Cassava stems were prepared in a small-scale set-up as the xylem was used as a filter. Effects of cross-sectional area and hydrostatic pressure were analyzed and the results showed a directly proportional relationship with permeate flow rate. Upon filtration with red dye solution, total dye removal was achieved using a xylem with a minimal length of 3 cm and onwards. While for bacteria removal, E. coli bacteria have been removed when tested with a bacteria count plate. Thus, this study demonstrated the potential of the xylem tissue of the cassava plant as affordable and available natural raw materials to be used as water filters during an emergency.

Effect of cross-sectional area and number of Fe nanoparticles on the thermal behavior of pool boiling heat transfer of the water-based nanofluid: A molecular dynamics study

Today, pool boiling heat transfer (HT) plays an important role in many industries and engineering systems. This study investigates the effect of factors such as cross-sectional area and the number of Fe nanoparticles (NPs) on pool boiling HT of water/Fe nanofluid (NF) in a microchannel. This research is performed using the molecular dynamics (MD) simulation. For this research, quantities such as maximum density, velocity, temperature, heat flux (HF) and phase change time are investigated. The results indicate that increasing the number of NPs reduces the phase-change duration. Adding the NPs to the base fluid improves the pool boiling HT. By reducing the cross-sectional area of the microchannel from 0.25 μm 2 to 0.09 μm 2 , the HF increases, and as a result, the pool boiling HT occurs at a higher rate. So, reducing the cross-sectional area decreases the phase-change duration from 0.33 to 0.30 ns. NPs due to the increase in HT surface, increase in effective thermal conductivity and uniformity of temperature changes in the base fluid leads to a very large increase in the heat transfer coefficient (HTC). Finally, it is expected that using these simulations, optimization of water/Fe NF behavior to enhance the pool boiling HT in micro-scale (microchannels) and nanoscale applications is done.

Effects of cross-sectional area and aspect ratio coupled with orientation on mechanical properties and deformation behavior of Cu nanowires

Metal nanomaterials exhibit excellent mechanical properties compared with corresponding bulk materials and have potential applications in various areas. Despite a number of studies of the size effect on Cu nanowires mechanical properties with square cross-sectional, investigations of them in rectangular cross-sectional with various sizes at constant volume are rare, and lack of multifactor coupling effect on mechanical properties and quantitative investigation. In this work, the dependence of mechanical properties and deformation mechanisms of Cu nanowires/nanoplates under tension on cross-sessional area, aspect ratio of cross-sectional coupled with orientation were investigated using molecular dynamics simulations and the semi-empirical expressions related to mechanical properties were proposed. The simulation results show that the Young’s modulus and the yield stress sharply increase with the aspect ratio except for the 〈110〉{110}{001} Cu nanowires/nanoplates at the same cross-sectional area. And the Young’s modulus increases while the yield stress decreases with the cross-sectional area of Cu nanowires. However, both of them increase with the cross-sectional area of Cu nanoplates. Besides, the Young’s modulus increases with the cross-sectional area at all the orientations. The yield stress shows a mildly downward trend except for the 〈111〉 Cu nanowires with increased cross-sectional area. For the Cu nanowires with a small cross-sectional area, the surface force increases with the aspect ratio. In contrast, it decreases with the aspect ratio increase at a large cross-sectional area. At the cross-sectional area of 13.068 nm2, the surface force decreases with the aspect ratio of the 〈110〉 Cu nanowires while it increases at other orientations. The surface force is a linearly decreasing function of the cross-sectional area at different orientations. Quantitative studies show that Young’s modulus and yield stress to the aspect ratio of the Cu nanowires satisfy exponent relationship. In addition, the main deformation mechanism of Cu nanowires is the nucleation and propagation of partial dislocations while it is the twinning-dominated reorientation for Cu nanoplates.

Pengaruh Variasi Girder Terhadap Perilaku Struktur Atas Jembatan Beton Prategang Akibat Gempa Horizontal

Earthquakes are dangerous natural disasters and cause damage on a large scale. Therefore, this study aimed to determine the mass participation of the structure, structure capacity, and performance levels. The analysis was carried out based on the spectral response, pushover, and FEMA-356 methods. In anticipation of the damage, the design of earthquake-resistant structures has become essential in structural design, especially in the bridge structure design. The bridge samples in this study were type I prestressed concrete bridges with a length of 37 m and a width of 4 m using ten variations of girders located at the Temef Dam. The results obtained are the most critical structural conditions occur in the transverse direction. The base shear maximum capacity is more significant in the longitudinal direction than in the transversal direction. The maximum displacement capacity is higher in the transversal direction than in the longitudinal direction. The effect of cross-sectional area and cross-sectional inertia of the beam girder on the structural’s capacity is the greater the cross-sectional area and inertia of the beam girder, the greater the capacity of the structures. All of The structure performance levels were Immediate Occupancy (IO).

Mechanical properties of Cu nanowires: Effects of cross-sectional area and temperature

Nanostructured materials likely exhibit different mechanical properties from the corresponding bulk materials and have potential applications in a variety of areas. In this work, we use molecular dynamics simulation with embedded-atom potential to investigate the dependence of the mechanical properties of Cu nanowires of square cross-section, including Young's modulus, yield stress and surface force, on cross-sectional area and temperature for the Cu nanowires with cross-sectional areas in a range of 13.1 to 117.6 nm2 in a temperature range of 100 to 500 K. The simulation results reveal that the Young's modulus increases with the increase of the cross-sectional area at the same temperature and decreases with the increase of temperature for the same cross-sectional area. The yield stress decreases with the increase of the cross-sectional area at the same temperature in the range of 100 to 400 K and increases with the increase of the cross-sectional area at 500 K, while it decreases with the increase of temperature for the same cross-sectional area. The surface force decreases with the increase of the cross-sectional area at the same temperature and with the increase of temperature for the same cross-sectional area. Semi-empirical expressions relating the mechanical properties to temperature are proposed. Using the semi-empirical expressions, the Young's modulus at 0 K is found to decrease with the decrease of the cross-sectional area, and the yield stress at 0 K is found to decrease linearly with the increase of the cross-sectional area.

Migration test and safety assessment of polyurethane adhesives used for food-contact laminated films

Abstract Migration test and safety assessment of polyurethane adhesives commonly used for food-contact laminated films are experimentally studied. Six harmful migrants from isocyanate residues and additives in adhesives are identified by combined GC–MS with NIST index and retention time of standard products. A series of migration tests regarding “LDPE-adhesive-LDPE” sandwiching laminated films are carried out, aiming to unfold the effects of temperature-time conditions, cross section and nanomaterials on the migration of identified compounds into food simulant isooctane. The results reveal that three of the six identified compounds, i.e., KH-560, 2,4-DTBP and DMPA, may migrate into isooctane. Temperature is found to be the most important factor on the migration behavior. From the slight effect of cross section area on migration of compounds, it can be concluded that compounds easily diffuse into substrates and migrate into isooctane by penetrating through the substrates rather than cross section. We also found that adding graphene and functionalized graphene neither promote the migration nor inhibit. For safety assessment, threshold of toxicological concern method is alternatively used to evaluate the migration. The estimated daily intakes of KH-560 and DMPA in solvent-free polyurethane adhesive laminated films exceed the safety threshold recommended by threshold of toxicological concern, while those in solvent-based adhesive laminated films do not.

Effects of axial impact load on the dynamics of an oilwell drillstring

This article studies the dynamics of oilwell drillstring under large and small axial impact loads. For the case of large impact load, the drillstring is regarded as a continuous bar under the impact load of a falling mass, and the energy conservation method is implemented. A sensitivity analysis is conducted to investigate the effect of cross-sectional area of the drill string on the impact stress. Results show that the design of drillstring with different cross-sectional areas is not a suitable method. In order to understand the effect of high-frequency small axial impact (applied from percussion tools or downhole generators) on the drillstring vibration, a mechanical model in which the drillstring is regarded as a 2-degree-of-freedom system under a harmonic force is developed. Sensitivity analysis on the effects of impact generator placement and impact frequency on drillstring dynamics are conducted. Results show that the impact generator should be installed near the drill bit and that high frequency is recommended to be used.

Investigation and Taguchi Optimization of Microbial Fuel Cell Salt Bridge Dimensional Parameters

One major problem of two chamber salt bridge microbial fuel cells (MFCs) is the high resistance offered by the salt bridge to anion flow. Many researchers who have studied and optimized various parameters related to salt bridge MFC, have not shed much light on the effect of salt bridge dimensional parameters on the MFC performance. Therefore, the main objective of this research is to investigate the effect of length and cross sectional area of salt bridge and the effect of solar radiation and atmospheric temperature on MFC current output. An experiment has been designed using Taguchi L9 orthogonal array, taking length and cross sectional area of salt bridge as factors having three levels. Nine MFCs were fabricated as per the nine trial conditions. Trials were conducted for 3 days and output current of each of the MFCs along with solar insolation and atmospheric temperature were recorded. Analysis of variance shows that salt bridge length has significant effect both on mean (with 53.90% contribution at 95% CL) and variance (with 56.46% contribution at 87% CL), whereas the effect of cross sectional area of the salt bridge and the interaction of these two factors is significant on mean only (with 95% CL). Optimum combination was found at 260 mm salt bridge length and 506.7 mm2 cross sectional area with 4.75 mA of mean output current. The temperature and solar insolation data when correlated with each of the MFCs average output current, revealed that both external factors have significant impact on MFC current output but the correlation coefficient varies from MFC to MFC depending on salt bridge dimensional parameters.

Study on AZ91D chip for injection molding (2nd Report, Effect of dimension on effective thermal conductivity after consolidation)

The purpose of this study is to propose an effective model to estimate the effective thermal conductivity of compacts made from magnesium alloy particles, considering the effects of particle size, temperature and pressure. In order to investigate the influence of the particle size, six kinds of particles were prepared in which the cross sectional area was different. The test particles made from AZ91D were poured into a compression vessel and then a given pressure was applied to the piston of vessel for six hours under constant temperature condition. After compression, effective thermal conductivity of compacts were measured by steady state comparative-longitudinal heat flow method. The numerical calculation considering two-dimensional steady heat conduction was also conducted by using the actual cross section of compacts. Test results showed that the effective thermal conductivity of compacts were increased with increase of applied pressure and temperature elevation. Calculation results also revealed that by considering the actual cross section of compacts, the effective thermal conductivity could be well estimated when filling fraction is lower than 0.8. However, when filling fraction is exceed 0.8, the effect of thermal contact resistance between particles on thermal conductivity is not negligible. The experimental equation of effective thermal conductivity of compacts was determined to discuss the effects of cross sectional area of particles.

Effect of cross-sectional area and number of flow paths on pump properties of a monopivot centrifugal blood pump

Effect of cross-sectional area and number of flow paths on pump properties of a monopivot centrifugal blood pump

Scale effects on premixed flame propagation of hydrogen/methane deflagration

An experimental study of scale effects on hydrogen/methane deflagration of premixed flame in venting ducts is presented. The experiments focused on the effect of scale on flame structure, premixed flame propagation speed and overpressure during hydrogen/methane deflagration. Six ducts with different cross-sections and lengths were used in the experiments. Tests were performed for stoichiometric hydrogen/methane mixtures with five hydrogen fractions (hydrogen fraction from 0 to 100%) under ambient conditions. In the experiment, the “tulip” flame disappeared with increasing cross sectional area and hydrogen fraction. Meanwhile, the tulip flame gradually appears and a more pronounced “tulip” flame is observed with increasing duct length. The effect of cross sectional area coupled with duct length on flame propagation can be attributed to the influence of aspect ratio, while the “tulip” flame formation is only found when the aspect ratio > 6.7. In the experiments, the maximum flame speed has the similar trend with laminar flame speed regardless of whether there was “tulip” flame formation and the maximum flame propagation speed occurs with an aspect ratio of 10. The maximum overpressure decreases with cross sectional area and increases with the length of the duct. The time corresponding to maximum overpressure, tmax decreases with hydrogen addition. Meanwhile, tmax increases with cross sectional area and length of duct.

射出成形用AZ91D粒子に関する研究（第1報，圧密後のかさ密度に与える粒子寸法の影響）

The purpose of this study is to propose an effective model to estimate the filling fraction of compacts made from magnesium alloy particles, considering the effects of particle size, temperature and pressure. In order to investigate the influence of the particle size, six kinds of particles were prepared in which the cross sectional area was different. The test particles made from AZ91D were poured into a compression vessel and then a given pressure was applied to the piston of vessel for six hours under constant temperature condition. During the testing, the displacement of piston was measured to evaluate the change of bulk density of compacts, and then the filling fraction was simply calculated by the ratio of bulk density of compacts and density of AZ91D. Test results showed that the filling fraction of the largest particles was lower than that of other particles in the temperature region between 523 K and 623 K. The densification rates of compacts were increased with increase of applied pressure and temperature elevation. The experimental equation of densification rates of compacts was determined to discuss the effects of cross sectional area on densification rate. Determination results showed that the transition point to the steady creep was increased with increase of cross sectional area of particles.

The effect of cross sectional area of tube on friction factor and heat transfer nanofluid turbulent flow

The effects of the tube specifications on the heat transfer in car radiator are significant to improve cooling system performance. Friction factor and heat transfer enhancement of three types of nanofluids flow through horizontal three shapes of tubes has been evaluated numerically. CFD model by using FLUENT software depending on finite volume method was conducted. TiO2 nanoparticles with volume fractions (1%, 1.5%, 2% and 2.5%) are suspended in water as a base fluid to be nanofluids is used in this study. On the other hand, three types of tubes (circular, elliptical and flat tube) are chosen with 3mm hydraulic diameter and 500mm length. Numerical results show that the increase in volume fraction of nanofluid due to increase in fluid flow characteristics and heat transfer enhancement as compared with base fluid. The results of CFD model are compared with experimental data available in literature, and there is a good agreement with deviation 2%.

123 コニカル型多孔群を通過する微小噴流と相互作用する音波の吸音特性(吸音・遮音構造)

This paper describes the experimental investigation on the acoustic absorption caused by interaction of sound waves with fine-scale jets through conical holes. The experiments were carried out on three types of perforated plate: one has the straight holes, another have semi-conical and conical. The experimental results showed that the absorption was enhanced by not only the fine-scale jets through the perforated plate but also the effect of cross sectional area of the holes. The fine-scale jets through the conical holes provided a better absorption coefficient over a wide frequency range.

Thermal performance analysis of arbitrary-profile fins with non-fourier heat conduction behavior

The thermal performance of variable cross-section fins is considered using the Maxwell-Cattaneo- Vernotte (MCV) heat conduction model. Four different fins, namely rectangular, triangular, convex, and concave fins, with a periodic thermal condition are examined. The governing equations are hyperbolic and are solved numerically using an implicit finite difference method. In the MCV model, the thermal wave propagates with a finite speed, and hence sharp discontinuities appear in the temperature profiles. In this study, temperature profiles at various times, heat transfer rates, and thermal efficiencies of Fourier and non-Fourier fins are presented. In addition, the effect of relaxation time is considered. The results show that the effects of cross-sectional area and relaxation time are considerable on the thermal performance of various non-Fourier fins. To validate our findings, the results for non-Fourier fins with constant cross-sectional area obtained from this study are compared to those of other numerical solutions. This comparison confirms the correctness of the current results.

THE EFFECTS OF THE CROSS-SECTIONAL AREA AND ASPECT RATIO OF BEAMS ON A LAMINAR CHANNEL FLOW

The study analyzed the fully developed laminar flow in a channel with longitudinal rectangular beams arrayed along the channel width. The governing equations describing the fluid which flows along the direction of the beam length are expressed with double Poisson equations and are solved by eigenfunction-expansion and point-match method. The effects of cross-sectional area and aspect ratio of the beams are investigated. Dimensionless velocity profile, mean velocity, and friction factor multiplied by Reynolds number in the channel are presented for analysis. Initially, a comparison of fRe for a special case is made. It is found that the predicted fRe of this work tends to approach that of a parallel-plate channel case for smaller A and ar. A further study shows that increasing the cross-sectional area of the beams will lead to a decrease both in the mean velocity and fRe values. For a fixed cross-section area of the beam, as the beam height increases, an increase in the mean velocity and volumetric flow rate of the fluid but a decrease in the fRe is obtained.

E204 大型熱音響冷却システムの実用化に向けた検討 : 管の断面積が熱から音へのエネルギー変換に与える影響(OS10 外燃機関・廃熱利用技術),動力エネルギーシステム部門20周年,次の20年への新展開)

E204 大型熱音響冷却システムの実用化に向けた検討 : 管の断面積が熱から音へのエネルギー変換に与える影響(OS10 外燃機関・廃熱利用技術),動力エネルギーシステム部門20周年,次の20年への新展開)

Comparative study on morphology of cross-section and cyclic fatigue test with different rotary NiTi files and handling methods

ABSTRACT 수종의NiTi 전동파일단면형태비교및pecking motion의사용방법이피로파절에미치는영향 김재관 1 ∙금기연 2 ∙김의성 1 * 1 연세대학교치과대학보존학교실, 2 서울대학교치의학대학원보존학교실 COMPARATIVE STUDY ON MORPHOLOGY OF CROSS-SECTION AND CYCLIC FATIGUE TEST WITH DIFFERENT ROTARY NITI FILES AND HANDLING METHODS Jae-Gwan Kim 1 , Kee-Yeon Kum 2 , Eui-Seong Kim 1 * 1 Department of Conservative Dentistry, Yonsei University, 2 Department of Conservative Dentistry, 2 Dental Research Institute, Seoul National University There are various factors affecting the fracture of NiTi rotary files. This study was performed to evaluatethe effect of cross sectional area, pecking motion and pecking distance on the cyclic fatigue fracture of dif-ferent NiTi files. Five different NiTi files-Profile � (Maillefer, Ballaigue, Switzerland), ProTaper ™ (Maillefer,Ballaigue, Switzerland), K3 � (SybronEndo, Orange, CA), Hero 642 � (Micro-mega, Besancon, France), HeroShaper � (Micro-mega, Besancon, France)-were used. Each file was embedded in temporary resin, sectionedhorizontally and observed with scanning electron microscope. The ratio of cross-sectional area to the cir-cumscribed circle was calculated. Special device was fabricated to simulate the cyclic fatigue fracture ofNiTi file in the curved canal,. On this device, NiTi files were rotated (300rpm) with different pecking dis-tances (3 ㎜or 6 ㎜) and with different motions (static motion or dynamic pecking motion). Time until frac-ture occurs was measured. The results demonstrated that cross-sectional area didn’t have any effect on thetime of file fracture. Among the files, Profile

Effects of cross-sectional area on resin-enamel tensile bond strength

Objective. It was hypothesized that there is an inverse relationship between resin-enamel bond strength and bonded cross-sectional area, and that there are regional differences in resin-enamel bond strength. Methods. The facial and lingual surfaces of extracted human third molars were ground down 0.3 mm using 240 grit abrasive paper and were then bonded with either Clearfil Liner Bond 2 or Scotchbond Multi-Purpose Plus adhesive systems using the manufacturer's instructions. The bonded surfaces then received a resin composite build-up. After 24 h of storage in water, the bonded teeth were vertically serially sectioned into 1.0 mm thick slabs using a diamond saw, and the bonded surface area at the resin-enamel interface was varied from 0.5 to 3.0 mmz using a diamond saw under microscopic observation. The trimmed region was varied from the occlusal third of the facial or lingual enamel to the middle third, to the cervical third. The trimmed specimens were then glued to a Bencor Multi-T device, placed in an Instron testing machine and stressed to failure at 1 mm/min. A three-factor ANOVA was used to compare bond strengths (buccal vs. lingual, occlusal vs. middle vs. cervical-third, vs. materials). Regression analysis was used to examine the relationship between bond strength and bonded cross-sectional area for each material on occlusal enamel. Results. For both bonding systems, there was a highly significant (p < 0.001) inverse exponential relationship between tensile bond strength (y axis) and bonded cross-sectional area (x axis) with y intercepts of 51 and 59 MPa for Clearfil Liner Bond 2 and Multi-Purpose Plus, respectively. Using both materials, the highest bond strengths were measured in the occlusal third, which were significantly higher (p < 0.05) than those made to cervical enamel. Significance. Like resin-dentin bonds, resin-enamel bonds exhibit an inverse relationship with cross-sectional area. This relationship becomes more apparent at bonded surface areas below 2 mm 2 and is probably due to reductions in the number of interfacial stress-raisers as samples are made smaller.