Hairpin Type Research Articles

Selection of phase change material for latent heat thermal energy storage using a hair-pin heat exchanger: Numerical Study

Abstract Phase change materials (PCMs) are promising for storing thermal energy as latent heat, addressing power shortages. Growing demand for concentrated solar power systems has spurred the development of latent thermal energy storage, offering steady temperature release and compact heat exchanger designs. This study explores melting and solidification in a hairpin-type heat exchanger (HEX) using three PCMs (RT 50, RT 27, and RT 35). A 3D model of the hairpin type heat exchanger (HEX) is drawn using Ansys-workbench. High-temperature fluid/Low-temperature fluid (HTF/LTF) with Stefan numbers (0.44, 0.35, and 0.23) flows through the inner pipe to charge the outer pipe's PCM. The Enthalpy-porosity model is used to study the melting and solidification of various PCMs, and the results were compared. Also, individual thermophysical properties that affect the heat transfer during the melting and solidification process have been discussed. It is observed that low thermal conductivity material with high latent heat is preferred for cold climates. In this study, RT 27 excels in cold climates due to extended solidification time, while RT 50 is effective in tropical regions due to its high melting points and lower latent heat.

A label-free activatable biosensor for in situ detection of exosomal microRNAs based on DNA-AgNCs and hairpin type nucleic acid probes.

Exosomal microRNA (miRNA) is a potential biomarker for cancer diagnosis, metastasis, and treatment. In situ detection of exosomal miRNA is an attractive option due to its simplicity and high accuracy. However, in situ exosomal miRNA detection has encountered challenges because of the low target abundance of targets and limited probe permeability. Herein, a label-free and activatable biosensor was developed for in situ exosomal miRNA assays by utilizing hairpin-shaped nucleic acid probes and DNA-hosted silver nanoclusters (DNA-AgNCs). The probe is directly internalized into the exosomes, and then hybridized with the target miRNA-21. Subsequently, the DNA-AgNCs are pulled closer to the G-rich sequence, ultimately leading to in situ red fluorescence activation. The biosensor not only can detect exosomal miRNA-21 but also distinguish cancer cells from normal cells. Under optimal reaction conditions, the detection limit (LOD) of exosomal miRNA-21 is 1.53 × 107 particles per mL. Furthermore, DNA-AgNCs are used as label-free signal elements for in situ detection of exosomal miRNAs for the first time, expanding the application of nanomaterials in this field. This strategy does not require tedious RNA extraction steps and expensive instruments, and may develop into a non-invasive diagnostic tool for ovarian cancer.

High Order Harmonic Pass Band Suppression in Microstrip Filter

It is very well understood that filters are backbone of communication system as they are employed in each stage of system design and the key parameters which indicates their performance and suitability to desired application are insertion loss, return loss, group delay etc. Apart from them a very important factor namely high order harmonic pass band which becomes very critical when input of the filter consists of multiple harmonic signal within it and creates interference to succeeding stages of the system. In order to achieve clean frequency spectrum in stop band frequency region, there is need of suppressing the high order harmonic spurious pass bands. In this research work additional microstrip patterns are formed at input/output of the filter schematic to achieve the required goal. In this article concept of the novel technique to eliminate or suppress the high order harmonics is detailed and same is implemented on hairpin type of filter topology.

Transition in Thermal History and Recurring Burial-Exhumation Cycles along Colder Thermal Gradients at the Archaean-Proterozoic Boundary: New Insights from the Western Dharwar Craton, South India

Abstract The Hole Narsipur Greenstone Belt (HGB), in the Western Dharwar Craton, South India, preserves evidence for three cycles of metamorphism spanning the Archaean–Proterozoic transition. Changes in metamorphic style across the transition are investigated using integrated petrographic, mineral chemical, metamorphic evolutionary history, conventional geothermobarometry, and phase equilibria modeling studies of rocks of diverse bulk rock composition from the belt. These rocks record signatures of three overprinting metamorphic cycles (M2 → M3 → M4 in sequence), postdating a Mesoarchaean, M1 event in the craton. The M2 cycle represents characteristic LP–HT metamorphism along a counterclockwise (CCW) metamorphic P–T path, peak metamorphism at 4–5 kbar, 515–595°C, and high thermobaric ratios (T/P ~1050–1525°C/GPa) at the M2 peak. The intermediate M3 metamorphic cycle records a prograde burial of partially cooled M2 rocks to middle-lower crustal depths, peak metamorphism at P ~7.5–10.2 kbar, T ~630–655°C, and corresponding intermediate T/P ratios (T/P ~620–875°C/GPa) and a retrograde stage, marked by combined exhumation and cooling to P ~5.3–6.4 kbar, T ~530–575°C. The resultant P–T paths of evolution show variability of clockwise (CW) paths from classical hairpin type to two-stage prograde heating segments. During the M4 metamorphism (TMax ~630–640°C at ~8.9–10.3 kbar and with lower T/P ratios at ~610–720°C/GPa), the partially exhumed M3 crust is re-buried to lower crustal depths along an intermediate thermal gradient as during the M3 metamorphic cycle. We interpret the thermal transition, tectonic thickening along a cooler thermal gradient, repeated burial-exhumation cycles in the orogenic wedge, and tectonic mixing of the three metamorphic cycles in terms of a three-stage tectonic evolution of the HGB. These in a sequence are (a) the development of a hot and thinned crust (cf. M2 cycle), (b) the transition to a thickened crustal zone tectonic domain (cf. M3 cycle), with both the domains being part of the lithospheric peel-back driven convergence setting and (c) finally continental collision tectonics (cf. M4 cycle). The pulsating nature of orogenesis at the Archaean–Proterozoic boundary deduced here distinguishes the Western Dharwar Craton from other cratonic blocks globally at the same time frame.

에도시대 여자 머리장신구 특성에 관한 연구

This study analyzed the sociocultural meaning and characteristics of various women’s hair accessories decorated in hair bun(髷) of the Edo period according to the classification of types. The development of women’s hair accessories in the Edo period was related to the development of Kabuki fashion, brothel, and the development of the publishing industry due to the expansion of educated people and the pursuit of pleasure according to social and cultural material abundance. Also, it was accelerated through the Sankin-kōtai(参勤交代制). Hair accessories in the Edo period were divided into four types, headband ornaments, combs and hairpins, symbol ornaments, and auxiliary ornaments. In addition, the characteristics of four types were analyzed. The detailed research results are as follows. First, hair bun accessories were broadly classified into Motoyui(元結) and headdress cloth. In the early Edo period, Motoyui, a paper material, was used for economy and practicality for tieing hair buns. Later, gold and silver foil papers were used, and Emotoyui(絵元結) was developed, and colorful headdress fabrics made of crape(縮緬) were used. Second, as the combs and hairpins became diversified and materials became luxurious, the form became more prominent, and the style became splendid. Kushi(櫛) developed into a thick, large comb called Okushi. There is a primary type of hairpin, Kogai, and Kanzashi includes Hanakushi and Bira-bira kanzashi. Third, it was considered that the symbolic ornaments revealed the status of the Edo period. Hirabitai(平額) worn by women in the royal family and royal family is typical, and there were Ichidome(位置止) and Kanokodome(鹿の子止), which were worn by Geisha and became popular. Fourth, as an auxiliary ornament, Kamoji(髢) means a wig, and it was seen that it plays a decorative role to enlarge and enhance the image.

A novel fluorescent peptide probe for the specific detection of Cu<sup>2+</sup> and Cys in cells

<p indent=0mm>As the third most abundant essential trace elements in the organism, Cu²⁺ plays an important role in normal physiological activities and metabolism, while excessive Cu²⁺ has been found to be closely related to serious diseases such as Down’s syndrome and Alzheimer’s disease. As an indispensable amino acid in the organism, Cys participates in the regulation of protein synthesis, post-translational modification and other biological functions. However, its pronounced accumulation may cause neurotoxicity, liver damage, kidney stones and other diseases. Therefore, the development of efficient assays for Cu²⁺ and Cys is critical for the diagnosis and treatment of these diseases. We have synthesized a hairpin type fluorescent peptide probe P ((Dansyl-Glu-Asp)₂-Lys) by using two amino groups in the side chain of lysine to react with aspartic acid in the peptide sequence. We found that the peptide probe P can highly specifically detect Cu²⁺ by fluorescence quenching without the interferences of other metal ions. The formation of P-Cu biosensor at 1:1 stoichiometry can highly selectively detect Cys and recover its fluorescence. We have demonstrated that the fluorescent peptide probe P provides an “On-Off-On” sensing mode for Cu²⁺ and Cys with detection limits of 52 and 43 nM, respectively. The fluorescent peptide probe P has been successfully used for the imaging of Cu²⁺ and Cys in HeLa cells. The newly developed fluorescent peptide probe P has extraordinary features such as good biocompatibility, low biotoxicity, and high specificity of Cu²⁺ and Cys, which shows new detection method in the studies of various Cu²⁺/Cys-involved diseases.

The Performance of the hairpin type U Shape Double pipe heat exchanger type under effect of using Passive and Active Techniques.

The process of improving and developing heat exchanger performance has received a lot of attention, and efforts are still being made by specialized researchers and engineers with a huge investigations to increase rate of heat transfer to lessen the volume size and price cost of the factories apparatus accordingly. In this experimental study, a suitable heat exchanger equipped with flow meters and thermocouples for measuring flow rates and temperatures was used with the U shape hairpin type exchanger. The bending and angle of curvature of the tubes causes vortex flow, which greatly aids to attractive the rate of heat transfer process and increase the performance, The effect of active and passive techniques with different positions of the U shape Exchanger like position (U shape and Inverse U shape ) as parallel coupling with tube liquid in series is investigated during this study. passive technique represented using the O ring fin type. and an active technique represented by the injection of an air bubble by a small compressor through a special air diffuser. The results show that the best application was with inverse U shape (∩) and the performance enhanced about (19.1%) in the case of active techniques while and (11.1%) with passive techniques and by applying both techniques together, the overall enhancement was (30.272%), So this study provides new visions for further studies.

An investigation of the gravity effects on pool boiling heat transfer via high-fidelity simulations

Nucleate pool boiling simulations are carried out to study the effects of gravity on the dynamics of bubble formation, bubble departure, and the mutual bubble interactions. We focus on identifying the dominant trends associated with the flow and thermal behavior at different gravity levels using fixed values of wall superheat and liquid subcooling. This is accomplished by measuring the contributions to heat flux associated with turbulent flow resulting from the dynamics of bubble interaction. The time averaged fluctuations of velocity and temperature indicate that the wall heat flux conditioned by the wetted surface area - the liquid heat flux - provides a useful indication of high heat flux hot spots. Furthermore, despite substantial differences in the dynamics of large scale bubbles at different gravity levels, the average heat flux in the liquid region is found to be dominated by the sliding and merger type events associated with small scale bubbles over a wide range of gravity levels. This significance of near-wall, small scale bubble dynamics is reflected in the transition of vorticity structures from hairpin type vortices in the near-wall region to vortex ring patterns away from the wall. While the maximum value of average turbulent fluctuations occurs away from the wall for earth normal gravity, the near-wall peak is only slightly lower and is similar in magnitude to that in the case of low gravity. These observations reveal the significance of small scale dynamics in affecting the heat transfer which was previously thought to be dominated by large scale bubbles, particularly at low gravity levels.

Conceptual design overview of the ITER WCLL Water Cooling System and supporting thermal-hydraulic analysis

In this paper, the conceptual design of the International Thermonuclear Experimental Reactor (ITER) Water-Cooled Lithium-Lead (WCLL) Test Blanket Module (TBM) Water Cooling System (WCS) from Europe is presented. The system consists of two loops in series. This design feature allows the removal of heat from the TBM box avoiding at the same time the release of radionuclides into the ITER Component Cooling Water System (CCWS), that acts as WCLL Test Blanket System heat sink. For this purpose, the WCS primary loop deals with the direct heat removal from the ITER TBM and the secondary one implements physical separation between the contaminated primary loop coolant and the CCWS. The insertion of an economizer into the primary loop determines the characteristic “eight” shape of the circuit. This choice was done in order to reduce the temperature difference on the intermediate heat exchanger. Hairpin type and steam bubble are the technologies selected for heat exchangers and pressurizers, respectively. Pressure and temperature control systems are foreseen to limit excursions from rated values in normal operational states and abnormal transients.A computational activity was promoted to assess the WCLL-WCS conceptual design, using a modified version of the RELAP5 Mod3.3 system code. A detailed thermal-hydraulic model was developed on the basis of design outcomes. The nodalization scheme includes the TBM, the WCS, a portion of the CCWS and the lithium-lead circuit. The computational campaign involved both the normal operational state and selected abnormal transients. In all the scenarios simulated, the conceptual design has highlighted the capability of operating the system respecting all the thermal-hydraulic requirements. The abnormal transient selected and presented is the loss of flow in the CCWS (loss of heat sink). In these conditions, TBM cooling function has been verified, keeping standard control strategies without any external action.

Asymmetric vortex shedding in the wake of an abruptly expanding annular jet

In this paper, the structure of the turbulent wake behind the inner tube of a suddenly expanding annular jet flow is studied. The flow field is measured using tomographic particle image velocimetry and analyzed using proper orthogonal decomposition (POD). It was found that both the instantaneous and time-averaged central wakes behind the inner pipe are highly asymmetric despite the axisymmetric structure of the geometry. This asymmetry is the result of a bifurcation at low Reynolds numbers which persists up to the turbulent regime. The asymmetry induces a pair of counter-rotating vortices in the jet which are aligned with the main flow direction. Moreover, the asymmetry also induces a highly dynamical flow field. Analyzing the flow structures using POD shows that the wake oscillates around the asymmetric equilibrium position at a very low Strouhal number in the order of 0.01. On top of this motion, the inner shear layer oscillates with Strouhal numbers in the range of 0.1-0.3. This oscillation causes an asymmetric shedding of vortices of the hairpin type in the inner shear layer. As such, a local asymmetric region of very intensive mixing is induced near the stagnation point.

Mechanisms underlying genome instability mediated by formation of foldback inversions in Saccharomyces cerevisiae.

Foldback inversions, also called inverted duplications, have been observed in human genetic diseases and cancers. Here, we used a Saccharomyces cerevisiae genetic system that generates gross chromosomal rearrangements (GCRs) mediated by foldback inversions combined with whole-genome sequencing to study their formation. Foldback inversions were mediated by formation of single-stranded DNA hairpins. Two types of hairpins were identified: small-loop hairpins that were suppressed by MRE11, SAE2, SLX1, and YKU80 and large-loop hairpins that were suppressed by YEN1, TEL1, SWR1, and MRC1. Analysis of CRISPR/Cas9-induced double strand breaks (DSBs) revealed that long-stem hairpin-forming sequences could form foldback inversions when proximal or distal to the DSB, whereas short-stem hairpin-forming sequences formed foldback inversions when proximal to the DSB. Finally, we found that foldback inversion GCRs were stabilized by secondary rearrangements, mostly mediated by different homologous recombination mechanisms including single-strand annealing; however, POL32-dependent break-induced replication did not appear to be involved forming secondary rearrangements.

Mercuric ion detection by plasmon-enhanced spectrophotometric ellipsometer using specific oligonucleotide probes.

Pollution due to heavy metal ions, including mercury, has become a major issue because of their toxicities. It is required to monitor mercury levels in aqueous media using fast and selective methods with high accuracy. Ellipsometry is a promising technique for instance when it's combined with the plasmon resonance phenomena. We reported a biosensor system available for qualitative/quantitative determination of mercuric ions in aqueous media where both the spectrophotometric ellipsometry and oligonucleotide recognition elements were used. A single step assay using both a linear (ProbeL) and a hair-pin (ProbeH) type oligonucleotide probe as a recognition element, in addition to a sandwich-type (ProbeLS) assay were developed and compared. The detection limits were 0.23 nM, 0.03 nM and 0.15 pM for ProbeL, ProbeH and ProbeLS, respectively. The detection range was between 0.05nM and 100nM Hg2+ for all assays proposed herein.

Could Microwave Irradiation Cause Misfolding of Peptides?

Microwaves have been experimentally shown to affect the folding dynamics of peptides and proteins. Using molecular dynamics, we performed all-atom simulations of a model β-peptide in aqueous solution where individual degrees of freedom of solvent molecules were decoupled to allow for investigation at non-equilibrium microwave-irradiated conditions. An elevated rotational temperature of the water medium was found to significantly affect the conformation of the peptide due to the weakened hydrogen-bonding interactions with the surrounding solvent molecules. Cluster analysis revealed that microwave irradiation can indeed act as a promoter in the formation of new misfolded peptide structures of the hairpin type, which are generally associated with the onset of several neurodegenerative disorders such as Alzheimer’s, Parkinson’s, Huntington’s, and Creutzfeldt–Jakob diseases as well as certain cancer types such as amyloidosis.

Design of High Power Density and High Efficiency Wound-Field Synchronous Motor for Electric Vehicle Traction

This paper deals with a design method to improve the power density and energy efficiency of a wound-field synchronous motor (WFSM) using hairpin type rectangular wire for electric vehicle traction. First, the prototype is analyzed via experiments to come up with plans to improve it. In addition, mechanical loss of the prototype including the bearing and brush friction losses is obtained and used for designing the improved motor. After then, an analytical approach is presented for the magnetic circuit design to minimize magnetic resistance in the motor core. Also, the analytical methods are proposed to predict the resistance of the field and armature windings. At this step, rectangular wire is considered for the armature winding to reduce the copper loss. Moreover, the calculation process is presented to estimate the iron loss considering harmonics. The performances such as power density and efficiency of the improved WFSM are analyzed and compared with those of the prototype. In addition, the energy efficiency of the motors in the new European drive cycle (NEDC) is analyzed. Finally, the performances of the improved WFSM are compared with the experimental results to verify the validity of the proposed design process.

Formation of dome-in-dome structures: Results from experimental studies and comparison with natural examples

Dome-in-dome structures are frequent in salt provinces and in high-grade rocks of orogens. Their origin is only poorly understood. In the present study we have modelled dome-in-dome structures, which result from constrictional (radial) in-plane shortening of a competent layer embedded in a rising less competent matrix. Both the layer and the matrix consist of non-linear viscous plasticine, which display a viscosity contrast of 5. The deforming competent layer is characterized by (1) a striking downward drag along the margins, (2) a sample-scale first-order dome, and (3) numerous second-order domes and basins straddling the first-order dome. With increasing layer thickness and strain, the amplitude, A, arc-length, L, and wavelength, λ, of the second-order domes and basins increase. However, their growth rate is significantly smaller than that of non-rising domes and basins, which result from a bidirectional flow. This restricted growth of rising domes and basins is attributed to the simultaneous growth of the first-order dome, and explains, why hair-pin type folds – typical for non-rising domes and basins - are lacking, even at higher finite strain.Similar dome-in-dome structures like those produced in the present study have been described from deeper levels of salt and gneiss domes or from foliation triple points of interfering diapirs.

Turbulent structures in cylindrical density currents in a rotating frame of reference

ABSTRACTGravity currents are flows generated by the action of gravity on fluids with different densities.In some geophysical applications, modeling such flows makes it necessary to account for rotating effects, modifying the dynamics of the flow. While previous works on rotating stratified flows focused on currents of large Coriolis number, the present work focuses on flows with small Coriolis numbers (i.e. moderate-to-large Rossby numbers). In this work, cylindrical rotating gravity currents are investigated by means of highly resolved simulations. A brief analysis of the mean flow evolution to the final state is presented to provide a complete picture of the flow dynamics. The numerical results, showing the well-known oscillatory behavior of the flow (inertial waves) and a final state lens shape (geostrophic adjustment), are in good agreement with experimental observations and theoretical models. The turbulent structures in the flow are visualized and described using, among others, a stereoscopic visualization and videos as supplementary material. In particular, the structure of the lobes and clefts at the front of the current is presented in association to local turbulent structures. In rotating gravity currents, the vortices observed at the lobes front are not of hairpin type but are rather of Kelvin-Helmholtz type.

МОДИФІКАЦІЯ МОДЕЛІ ВПЛИВУ КЛІМАТИЧНИХ ФАКТОРІВ НА ФОТОСИНТЕЗ СОСНИ В УМОВАХ ПІВДНЯ УКРАЇНИ

The article describes the method of calculation of plant vegetation photosynthesis and its modification to the spikes in the South of Ukraine. The object of the study is the Tsyurupinsk forest-hunting farm, which is located in the Kherson region, on the Nizhnedneprovsky sands. Artificial forest in the Steppe zone of Ukraine is of interest as a factor influencing the climate of this area. The subject of the study is pine needles, which is dominant. The place of simulation is determined as the driving force behind the development of science. The existing modeling methods that are most often used in practice are described. Existing models of calculation of photosynthesis are presented and the second is specified сonsidered what are the models based and what results can be obtained for their use. Component of the method of calculation of vegetation photosynthesis, developed by Polevoy A. M, is demonstrated. The proposed method is implemented in Fortran language using standard agrometeorological information. The data can be used both for a single station and average characteristics for areas, regions and soil - climatic zones. The blocks of data necessary to calculate the intensity of photosynthesis are shown. The data necessary for the implementation of this model is drawn up. The modification of the method to the studs, which were chosen as the object of research, is described. For the subject of research, the pinholes of studs are chosen, because it is a productive assimilation apparatus. The calculations of this modification are shown in the form of tables. They allow us to see the influencing agrometeorological factors and the area, growth, photosynthesis of the research subject. The results of the simulation are presented separately for the Crimean pine and for the common pine. The average of the decade's effective temperature for this region of the study varied from 3,3 to 12,2 °C. The sum of effective temperatures with an increasing amount during the growing season of the needle increased from 36,3 to 517,5 °C. The average per decade intensity of the FAR over the shoots for both types of hairpins varied from 0,25 to 0,33 cal/cm2 min. For the decade, the intensity of the FAR in the shoots of the Crimean pine needles was from 0,12 to 0,5 cal/cm2, while in the pine usual 0,17-0,09 cal/cm2 min. The results of the calculation of the area, photosynthesis and growth of the needle pin are different. The area of the Crimean pine needles varies from 2,3 to 5 mm2, and the pine is usual from 0,9 to 2 mm2 during the first six decades. The difference in the area of the needles of the studied studs is 3 mm2. The intensity of photosynthesis under optimal conditions on the temperature and humidity of the soil for both studs is 1,2 СО2/dm2 h. The intensity of photosynthesis in the field conditions in the Crimean pine grows during the first three decades from 0,1 to 0,3 СО2/dm2 h., аnd in the pine common from 0,1 to 0,2 СО2/dm2 h. during the first four decades. Photosynthesis of shoots per day differs by 0,7 g/m2. The height of this indicator is observed during the first three decades: in the Crimean pine from 0,2 to 1,2 g/m2, and in the pine common from 0,1 to 0,5 g/m2. The indicator of the growth of the total mass of shoots for a decade in the Crimean pine increases from 2,1 to 8,8 g/m2, and in the pine usual from 0,8 to 3,5 g/m2. The growth of the Crimean pine needles is 5,3g/m2 larger. An analysis is made of the results obtained in the modification of the model for the calculation of photosynthesis. A conclusion is made on the success of the modification of the method for calculating vegetation photosynthesis to the hairpin.

Metamorphic Heads: A Footnote on Botticelli’s and Pollaiuolo’s Mercanzia Virtues

Metamorphic Heads: A Footnote on Botticelli’s and Pollaiuolo’s Mercanzia Virtues

Effect of the reflectional symmetry on the coherent hole transport across DNA hairpins.

The coherent hole transfer in three types of DNA hairpins containing strands with adenine (A) and guanine (G) nucleobases has been studied. The investigated hairpins involve An+1GGAn, AnGAGAn, or (AG)2nA strands that connect the hole donor and hole acceptor located on opposite ends of hairpins. The positive charge transfer from the photo-excited donor to the acceptor is shown to be slower for An+1GGAn in comparison with AnGAGAn and (AG)2nA sequences. We have revealed that this is due to the reflectional symmetry of the last two sequences with respect to the axis passing through the middle base. As has been demonstrated, the symmetry of the sequence structure manifests itself in the reflectional symmetry of the energy eigenstates. In addition, it has been shown that (AG)2nA is the only symmetric sequence with a zero energy state in the middle of the LUMO tight-binding energy band. Based on our theoretical findings, we predict that the hairpin with this sequence should have the fastest coherent hole transfer rate among the class of base sequences studied.

層流斑点の下流発達における撹乱強さの影響

In the final stage of laminar to turbulent transition, it was known that the regions called ‘turbulent spot' appear. When these spots develop downstream and the boundary layer fill with them, the transition process is finished. Previous studies have shown that development of spot was arranged by the energy of jet unrelated these shapes. The purpose of this study was to clarify growth and development proses of the spot using some shapes jet with same energy. From results obtained, the spot created by sharp jet grew faster than that created by flat-shape jet. In the spot created by flat jet, hair-pin type vortex induced secondarily was weak and wider than first one. The wide hair-pin type vortex could not create a strong low-speed shear layer between its legs. Consequently, growth of the spot created by flat-shape jet became slow.