Cross Ribs Research Articles

Heat transfer performance study of fluid rotating microchannel heat sink

The study presents a novel fluid rotating microchannel heat sink (FR-MC) and reports its heat transfer performance. The FR-MC features two cross ribs positioned in the channel. These cross ribs are inclined in the direction of fluid flow, with each rib inclining in opposite directions. This design enables the fluid to ascend or descend along the ribs, creating rotation after passing through the center to alter the flow direction. Experimental validation confirms the accuracy of the model and numerical simulations. The study investigates the heat transfer capability of FR-MC through comparative analysis, and explores the reasons for the improved performance. The results indicate a 45 % reduction in thermal resistance compared to a rectangular microchannel (R-MC). This improvement is attributed to the rotation of fluid promoting the exchange between the upper and lower parts and the mixing of hot and cold portions, effectively disrupting the thermal boundary layer near the wall. Further exploration into the impact of microchannel dimensions on heat transfer performance indicates that the FR-MC outperforms the R-MC across various heights and widths, achieving thermal resistance reductions ranging from 16 % to 50 %, illustrating the superior heat transfer performance of FR-MC.

Study on generating rolling method for manufacturing cylindrical parts with external cross ribs

As the main structure of launch vehicle, cylindrical parts with reinforced ribs are mainly manufactured by milling, rolling and welding methods, which have a long manufacturing cycle and low material utilization. This paper proposes a new generating rolling method for manufacturing cylindrical parts with external cross ribs integrally. The generating rolling device is developed, the flow mechanism of cylindrical parts with external cross ribs is revealed and methods to minimize the underfill defects of ribs are proposed. Simulation and experiment results show that longitudinal rib is mainly formed by gradual material accumulation in the groove under circumferential compressive strain, and transverse rib is mainly formed by gradual material accumulation in the groove under axial compressive strain. Compared with longitudinal or transverse rib, the material flow of cross rib is more difficult due to small circumferential and axial compressive strain, resulting in the underfill phenomenon. Rib structure also affects the flow of material. When the rib sparsity is large or the height-width ratio is small, the rib is subjected to small radial tensile strain and circumferential compressive strain, resulting in low rib height and uneven rib filling. The proposed forward and reverse rolling method and billet preforming method can reduce the defects of uneven filling of longitudinal rib and underfill of cross rib.

Numerical Simulation on Heat Transfer Augmentation by Using Innovative Hybrid Ribs in a Forward-Facing Contracting Channel

This study aims to investigate the thermal behavior and aerodynamic phenomena in a heated channel with varied rib configurations using computational fluid dynamics (CFD) simulations. Incorporating ribs in such systems enhances heat transfer and increases flow resistance and manufacturing costs. Understanding heat exchanger theory, measurement methods, and numerical calculations are crucial for creating efficient heat exchangers. The current research employs numerical analysis to assess the impact of hybrid ribs on heat transfer enhancement in forward-facing contracting channels (FFS). A two-dimensional forced convection heat transfer simulation under turbulent flow conditions was performed, considering the presence and absence of ribs with dimensions of 1 cm by 1 cm and spaced 11 cm apart. The arrangement of the ribs causes symmetrical temperature and flow distribution after and before each rib. The results demonstrate that the use of hybrid ribs outperforms the use of individual rib configurations in terms of thermal performance. This is due to the distinct flow patterns generated as the fluid passes through each rib. The triangle ribs had a more significant impact on the pressure drop than other rib configurations, while the cross ribs showed a lesser effect. The ribs improve the heat transfer coefficient while increasing the pressure drop, and the values of the Reynolds number were found to be directly proportional to the heat transfer coefficient and the pressure drop. The study concludes with a qualitative and quantitative analysis demonstrating the accuracy and coherence of the obtained computational results.

Study on multi-roller flow forming process of aluminum alloy cylinders with cross ribs

Study on multi-roller flow forming process of aluminum alloy cylinders with cross ribs

Multi-objective optimization of heat sink with multi-cross-ribbed-fins for a motor controller

A novel multi-cross-ribbed-fin layout was proposed to supersede the original smooth fin to fulfill the lightweight requirement of the air-cooled heat sink for the electrical vehicle motor controller. The thermal design with multi-cross-ribbed-fins was optimized using the multi-objective optimization method to minimize the chip’s temperature rise and the weight of the heat sink simultaneously. The design variables are the number of multi-cross-ribbed-fins ranging from 12 to 24, the number of cross ribs on either side varying from 1 to 4, and cross rib height in the region of 1.00–2.50mm. The standard k-ε turbulence model was validated compared to the experimental data for the original heat sink with smooth fins. The Pareto front solution set was obtained by performing the mixed-level orthogonal design procedure with the numerical simulations, constructing the surrogated-based model with backpropagation neural net training, and implementing the genetic algorithm. The numerical results showed that the recommended optimal designs have the multi-cross-ribbed-fin number of 17–19, the number of cross ribs of 2–3, and a cross rib height of 2.13–2.50mm. The maximum decreases in the temperature rise and weight are 7.63% and 9.45%, respectively. For verifying the superiority of current optimal designs, one of the optimal designs of the heat sink, which yields comparative temperature rise of the chip but reduced weight, was selected to be experimentally tested and compared with the data for the original heat sink.

Proposal and Verification of Countermeasures against Fatigue Cracking from Weld Joints between Trough Ribs and Cross Ribs in Orthotropic Steel Decks

Orthotropic steel decks (OSDs) have a problem on fatigue durability, while OSDs have advantages of light weight and short construction time. The effective countermeasure against fatigue cracking at welded joints between a deck plate and trough ribs have been already proposed. In this study, focusing on fatigue cracking at welded joints between trough ribs and cross ribs, countermeasures for existing structures and renewal and newly established structures are proposed, and verified through fatigue tests using a large specimen with similar scale as actual OSD structures. Principal results obtained through this study are as follows. By retrofit using TRS and angles for the existing structure, the sufficient effect of preventive countermeasure and post countermeasure against fatigue cracking at welded joints between trough ribs and cross ribs has been verified through fatigue tests. However, fatigue cracking at welded joints between a deck plate and trough ribs could not be prevented. In the new structure, any cracks have not been initiated from the connection between a trough rib and a cross rib, and a deck plate. The sufficient fatigue durability was confirmed.

The effect of loading mode on isothermal local loading forming of magnesium alloy rib-web component

The lightweight of aerospace equipment has urgent demand for the large-scale reinforced wall structure with higher strength and toughness. In this research, the isothermal local loading forming (ILLF) process was proposed to decrease the extremely larger forming load and promote the material filling at rib locations. A typical rib-web component with two cross ribs was investigated and the experiment setup was designed to fabricate it under three loading modes (two new local loading modes and one conventional integral loading mode). The parallel finite element (FE) models were established and verified by comparing the experimental points and simulation curve. The material filling effect and forming load were compared under three loading mode, and the Lode parameter together with hydrostatic pressure was applied to analyze these differences during the deformation processes. Based on the principle of more uniform equivalent strain and larger filling rate, the best loading mode was determined and its corresponding process parameters were optimized.

Egg Morphology and Chorion Fine Structure of Lepidopteran Pest Species <i>Nausinoe geometralis</i> (Guenée) (Crambidae: Spilomelinae)

The eggs of a species of subfamily Spilomelinae i.e., Nausinoe geometralis (Guenée) belonging to family Crambidae, commonly known as jasmine leaf webworm were examined through Scanning Electron Microscope (SEM) and studied their surface ornamentation displayed on the egg chorion to raise a taxonomic key for more accurate identification. Surface texture of the chorion considered in combination with overall shape was enough to distinguish all the species examined. The surface textures of egg shells can be used to describe, classify and identification of the species from taxonomic view point. The egg surface have a gap like structure denoted as micropyle which further contains rosettes, cross ribs and aeropyles which differs in higher taxonomic groups. In the species i.e., Nausinoe geometralis (Guenée), the egg chorion sculpture appeared as irregular ridges join the rosettes which surrounds the micropyle.

Fatigue behavior and retrofit of bulb rib orthotropic steel decks With R40 slits in cross beams

ABSTRACTA number of fatigue cracking experiences have been reported at the lower part of cross beam slits intersected by bulb ribs with R less than 35mm. In this study, fatigue behavior of cross beam slits with R of 40mm is investigated and effectiveness of retrofitting methods of R dressing and small size attachments, through fatigue tests using three specimens cut out from a removed bulb rib orthogonal steel deck box girder bridge. The shape and size of R dressing were determined through finite element analyses. As a result, stress concentration was higher at the upper part than the lower part of slits. By the R dressing, stress concentration moved from fillet welds to R part in the mother material. By the small size attachment, stress concentration decreased at the upper part of slits. Fatigue cracks were initiated at the upper part of R40 slits and propagated into fillet welds between the deck plate and cross ribs without retrofitting methods, while no fatigue cracks were developed with R dressing and small size attachments. After fatigue cracks were initiated, small size attachments could stop propagation, of there cracks.

Species Diversity and Structure of Wing Scales of Euploea and Papilio Butterflies from Phromlaeng, Nam Nao National Park, Phetchabun Province

This study focuses on species diversity of butterflies in the genera Euploea and Papilio in Nam Nao National Park. The butterflies were investigated every month for one year using insect nets. A total of 11 species, belonging to 2 genera and 2 families, were found. These were E. algea, E. camaralzeman, E. core, E. midamus, E. mulciber, E. radamanthus, E. sylvester, P. helenus, P. memnon, P. nephelus, and P. paris. The structure of the wing scales in different colour areas of 9 species was studied using a stereo microscope and a scanning electron microscope. The general structure of the wing scales of the butterflies of genus Euploea, independent of the colour it produces, is of longitudinal ridges, composed of tilted scutes, cross ribs that connect the ridges, and trabeculae, which link the cross ribs to the membrane of the wing scale’s upper lamina. In the Papilio species, there are 2 types of wing scales: one that exhibits blue-green iridescence and has wide-spaced ridges with concavities in between; and one displaying white, black, yellow, and red and has smaller widths between the ridges, with the space in between them containing a reticular pattern of cross ribs. The study of the wing scale microstructure of the butterflies in the Euploea and Papilio genera indicates that the patterns of the wing scale structure are genus-specific and that, despite showing similar colours, the wing scales are equipped with different mechanisms exemplifying diversity in structural coloration in nature.

Transmission of sound waves through a rectangular plate supported by a system of cross ribs

The stationary monoharmonic sound wave transmission through a thin plate of infinite extent, supported by a system of cross ribs on both sides is studied. It is assumed that the cross ribs are arranged with uniform steps along axes of Cartesian coordinate system related to the median plane of the plate and at the points of intersection centerlines plate rests on the ribs of finite length. Transverse loads acting on the plate cause only tension-compression deformation state on the ribs at zero displacement of their end sections. On cell of periodicity cut from the plate, concerned acousto-elasticity problem is formulated, which describes the interaction of the plate with acoustic environments located on both sides in the corresponding half-spaces. Dynamic deformation of the plate is described by the linearized equations of the classical theory of plates based on Kirchhoff–Love hypothesis, which take into account the internal friction of plate’s and reinforcing ribs material by Thomson–Kelvin–Voigt hysteresis model, and the motion of acoustic environments—by well-known wave equations. On the basis of the Ritz method using trigonometric basis functions at the exact satisfaction of the periodicity conditions of solutions on the boundary points of the periodicity cell and in its corner points—the conditions of compatibility of strains of the plate and support ribs, exact analytical solution of the problem is constructed. It is shown that the plate of this class at frequencies that do not coincide with the resonance is characterized by less than the value of sound insulation parameter than simply supported at all edges rectangular plate, and introducing reinforcing ribs into the mechanical system and increasing their rigidity leads to a significant change in the resonance frequencies and the dependencies of the parameters of stress-strain state and sound insulation of plates on the incident sound wave frequency.

The Study of the Structural Colouration Observed in the Papilio crino Fabricius, 1792 Wings

The research on nano-photonics has been on the increase recently. Among the materials that exhibit stunning optical properties are the nano-photonic materials found in nature such as those on butterfly wings. The wing scales of papilio crino was analysed using the Scanning Electron Microscopy (SEM), UV-Vis-NIR spectrometer, and Optical Microscopy (OPM). Under the OPM, the wing scales was imaged both in normal and polarized (45°) light. The SEM images reveal concave surfaces separated by repeating pattern of ridges and cross ribs. The variation in colour across the concave surface modulation was evident from the optical microscopy images. Through the numerical simulation and CIELab colour space, it was shown that the green colour seen on the wings is a combination of yellow and blue light reflected from different microscopic regions on the wing concave surface. This shows application in the bio-mimicks of retroflection sensors for the detection and classification of optical systems.

Testing and Evaluation of a Slot and Tab Construction Technique for Light-Weight Wood-Fiber-Based Structural Panels Under Bending

Abstract This paper presented construction and strain distributions for light-weight wood-fiber-based structural panels with tri-grid core made from phenolic impregnated laminated paper composites under bending. A new fastening configuration of slots in the faces and tabs on the core was applied to the face/core interfaces of the sandwich panel in addition to epoxy resin. Both normal strain gages and shear strain gages were attached on these panels to analyze inside strain distributions by third point load bending test. The purpose of the bending test was to investigate the various strain distributions of panels with different face/core configurations that identified the critical failure modes for future design. In this research, four panels with different configurations were constructed to analyze the influence of strain distributions for bending behavior. Either maximum localized normal strain or shear strain were used to judge failures and associated failure modes through observation. Test results of strain distribution showed normal strain was primarily carried by both top and bottom faces. As bending load increased, compression buckling occurred on the top surface of some panels with thinner faces. Face thickness and stiffness significantly affected the strength of the panel as evident by nonlinear strain behavior. Meanwhile, the shear strain was primarily taken by the ribs in the structural core, and shear failure always occurred in the longitudinal linear ribs of core with thicker faces. The shear strain in the cross ribs was approximately half that of the longitudinal linear ribs in the same section of shear zone, which was consistent with the geometric formula. The problem of panel imperfections resulting in either face compression buckling or rib shear buckling could be overcome by further design optimization, and the analytical modeling for bending design and evaluation was presented.

Genetically determined patozoospermia. Literature review and research results

Genetic factors (chromosomal aberrations and point mutations) are the cause of infertility in 10–15 % of men with impaired fertility. Homogeneous structural and functional defects in the sperm or the total terato-, asthenozoospermia – rare cases of genetically determined male infertility, are autosomal recessive diseases. Currently, described 4 types of «syndromic» spermopatology. 1. Primary ciliary dyskinesia (PCD) in men with total asthenozoospermia. Affects axoneme structures (microtubules, dynein arms, radial spokes). It identified more than 20 chromosomal loci responsible for the development of the PCD. 2. Dysplasia of the fibrous sheath of sperm tail in men with asthenozoospermia. The shortened and thickened sperm tail observed with disorganization of vertical columns and cross ribs of the fibrous sheath. Candidate genes – genes family ACAP. 3. Globozoospermia in men with teratozoospermia characterized by the presence of sperm with round heads, primary lack of acrosome and disorganization middle part of the flagellum. Found mutations or deletions of genes SPATA16, PICK1 and DPY19L2. 4. Syndrome decapitated spermatozoa in men with teratozoospermia (microcephaly). Abnormalities in the spermiogenesis development of connecting part jf the tail and proximal (morphologically normal) centrioles. In 2012–2014 years we have studied the ultrastructure of 2267 semen samples of men with impaired fertility. Globozoospermia revealed in 7 patients, dysplasia of the fibrous sheath – 13, decapitated sperm – in one. PCD was revealed in 4 patients (lack of axoneme dynein arms was found in 1 patient, absence of axoneme radial spokes – in 3 patients. The problem of genetically determined patozoospermya must be taken into account when the assisted reproductive technologies practises. There are few cases of successful assisted reproductive technologies with sperm of these patients. We don»t know the etiological factors of syndromic spermopatologe, so we cannot determine the degree of genetic risk.

Large-eddy simulation of vortical structures in a forced plane impinging jet

Large-eddy simulations (LES) of two plane impinging jets have been conducted. Predictions were first conducted for a natural impinging jet and found to be in good agreement with the experimental data of Yoshida et al. The validated code was then used to study the vortical structures of a forced impinging jet which had been experimentally investigated by Sakakibara et al. The numerical results show that the predictions have clearly captured the spanwise rollers, successive ribs, cross ribs and wall ribs observed by Sakakibara et al. They also show the predicted average convection velocity to be in good agreement with the measured value. Overall, the present study demonstrates the potential of LES simulations as a reliable tool to optimize the performance of engineering systems involving the use of forced impinging jets by regulating cross ribs through the inlet perturbations.

The effect of geometric structure on stiffness and damping factor of wood applicable to machine tool structure

Stiffness and vibration damping capability are important criteria in design of machine tool structure. In other sides, the weight of machine tool structure must be reduced to increase the handling capability. This paper presents an analysis of the effect of geometric structure on stiffness and vibration damping of wood structure. The stiffness was analysed using numerical method, so called finite element method (FEM), while the vibration damping capability was experimentally tested. Vibration testing was also performed to wood structures with sand powder filled into its rectangular hole to observe the its effect on damping factor. Simulation results show that the cross ribs structure yielded minimum mass reduction ratio compared to the three square holes as well as the single rectangular hole structures. While the vibration test results explained that the damping factor of Shorea laevis wood was higher than that Hevea braziiensis wood. The use of sand powder as vibrating mass in closed-box structure effectively increased the damping capability, for single rectangular hole structure the damping factor was increased from 0.048 to 0.079 doi : http://dx.doi.org/10.12777/ijse.4.2.2013.57-60 [ How to cite the article: Widyanto, S. A., Widodo, A., Nugroho, S., & Siahaan, D. (2013). The effect of geometric structure on stiffness and damping factor of wood applicable to machine tool structure. INTERNATIONAL JOURNAL OF SCIENCE AND ENGINEERING , 4 (2), 57-60. doi: http://dx.doi.org/10.12777/ijse.4.2.2013.57-60 ]

Effects of Pin Detached Space on Heat Transfer in a Rib Roughened Channel

An experimental study is performed to investigate the heat transfer characteristics and frictional losses in a rib roughened channel combined with detached pin-fins. The overall channel geometry (W = 76.2 mm, E = 25.4 mm) simulates an internal cooling passage of wide aspect ratio (3:1) in a gas turbine airfoil. With a given pin diameter, D = 6.35 mm = [1/4]E, three different pin-fin height-to-diameter ratios, H/D = 4, 3, and 2, were examined. Each of these three cases corresponds to a specific pin array geometry of detachment spacing (C) between the pin-tip and one of the endwalls, i.e., C/D = 0, 1, 2, respectively. The rib height-to-channel height ratio is 0.0625. Two newly proposed cross ribs, namely the broken rib and full rib are evaluated in this effort. The broken ribs are positioned in between two consecutive rows of pin-fins, while the full ribs are fully extended adjacent to the pin-fins. The Reynolds number, based on the hydraulic diameter of the unobstructed cross section and the mean bulk velocity, ranges from 10,000 to 25,000. The experiment employs a hybrid technique based on transient liquid crystal imaging to obtain distributions of the local heat transfer coefficient over all of the participating surfaces, including the endwalls and all pin elements. The presence of ribs enhances local heat transfer coefficient on the endwall substantially by approximately 20% to 50% as compared to the neighboring endwall. In addition, affected by the rib geometry, which is a relatively low profile as compared to the overall height of the channel, the pressure loss seems to be insensitive to the presence of the ribs. However, from the overall heat transfer enhancement standpoint, the baseline cases (without ribs) outperform cases with broken ribs or full ribs.

Effect Of Cross Ribs and Rigidity Of Middle Supports on the Behavior Of One Way Ribbed Slabs

AbstractThe effect of cross ribs and the rigidity of middle supports on the behavior of one way ribbed slabs were introduced in this paper. The 3D-FEM model through (ANSYS) program has been used to accomplish this study. The ultimate load, the cracking load, the strain of concrete, stress of steel and deflection of the analyzed slabs were calculated as well as mode of failure was observed. The optimum reinforcement, cross section and the location of cross rib as well as the effect of middle beam on the behavior of slabs were concluded.

Comparison of ultrastructure among sibling species of Ostrinia (Lepidoptera: Crambidae) from China

AbstractScanning electron microscopy on the ultrastructure of scales on the forewings and labial palpi suggests species-diagnostic differences among six sibling species of the genus Ostrinia Hübner. Among four species with small mid-tibiae, O. furnacalis (Guenée) and O. nubilalis (Hübner) show similar ultrastructure of the distal forewing scales, which is distinctly different from that of O. orientalis Mutuura and Munroe and O. dorsivittata (Moore). The diameter of windows between longitudinal ridges and cross ribs of forewing scales in O. dorsivittata is the largest among examined species, and clearly different from that in the other three small mid-tibiae species. Scales of the labial palpi of O. orientalis have indistinct vestigial windows; windows of O. nubilalis are more numerous and larger than in the other three small mid-tibiae species. Among two species with massive mid-tibiae, window diameter of forewing scales is larger in O. zealis (Guenée) than in O. scapulalis (Walker). Moreover, the number and diameter of windows in scales of the labial palpi differs between these two species. In addition to other known morphological differences, these ultrastructural differences provide further evidence that closely related Ostrinia species are distinct.

蚊子腿表面多级微纳结构的超疏水特性

Mosquitoes are a type of amphibian insects with remarkable ability to walk freely, lay eggs and safely take off or land on the water surface without drowning. This article reports the water repellency mechanism of mosquito legs. The maximal supporting force of a single hind leg against water surprisingly reaches up to 600 μN, over twenty times the total body weight of this insect. While for the artificial leg made with the wire which has the same diameter, shape and structure to the mosquito leg, the supporting force is only 85 μN, far less than the value of mosquito leg. Scanning electron microscope (SEM) observations reveal the uniquely hierarchical micro-nano structure on the legs, consisting of numerous oriented ten-micro scales with uniform sub-micro longitudinal ridges and nanometer cross ribs. The surface of mosquito leg has superior water repellency, and its static contact angle is about 153°. We theoretically demonstrate that the hierarchical micro-nano structure on the surface of the mosquito leg renders such superior water repellency and high water-supporting force. This finding might be helpful in the design of innovative non-wetting materials.