Pitch Distance Research Articles

Rapid template-assisted self-assembly: a practical route to the fast assembly of colloidal particles

Simple and quick techniques for assembling nanoparticles in topographically designed Poly(dimethylsiloxane) moulds of nanosized shapes have great potential in many spectroscopic and sensing tools. Close-packed particles pose rich plasmonic resonances, enabling the optical response to be tailored on both the nano- and macroscale. Template-assisted self-assembly (TASA) is a method that creates colloidal aggregates with controlled sizes formed by dewetting aqueous dispersions of NPs across surfaces. We present rapid TASA (rTASA), a modified version with an overall process time of under 10 min, improving speed and user-friendliness. Depending on the array pitch distance and average number of NPs per trap, the transmission through the template drops by between 20 and 80%, enabling them to be detected with even the simplest spectroscopic solutions. This rapid method is useful as a building block to generate self-assembled systems that exhibit exciting optical properties in crucial areas, particularly in building a fast test for size-selective NP detection.Graphical abstract

The Concept of Harmony and Modulation in Kwanji Sempidi's Gambang

Gamelan Gambang is a Balinese musical ensemble that has a unique and distinctive characteristic of its musicality. Gamelan Gambang belongs to gamelan saih pitu (seven notes), where in one octave the tone consists of seven principal notes. Each of the instruments in the Gambang Kwanji Sempidi gamelan has a different concept of tone harmonization and tone modulation. The method used in this study uses a type of qualitative descriptive research method through data collection using observation, interview, discography, and documentation methods. While measuring the frequency of the tone using the Curltone application tool. Through this method, in the Gambang Kwanji Sempidi gamelan, harmony appears in the arrangement of the Gambang tones on each Gambang instrument. Harmony is related to the interval or pitch distance. The pitch distance between dAng (A) and dang (a) is called ngembat or octave, the distance between dAng (A) and dEng (e) is called ngepat or ngempyung (kwint), while the distance between dAng (A) and dOng (o) tones called nelu or quart. If they are hit together in one tone simultaneously, four forms of tone harmonization patterns occur (nelu, ngepat, and ngembat). The harmony playing pattern on the xylophone is supported by the gambang beater (panggul) which has been set in such a way. The xylophone panggul has a different distance between the right and left pairs of mallets. The left pair spans four notes, while the right pair spans five notes. The Gambang Kwanji modulation system, namely the transition from one basic tone to another, is called Sengkeran. In the game, there is a change of one note in the order of the notes used. This sengkeran is found in the Gambang Labdha and Manukaba songs.

Characteristics of hydrogen separation and methane steam reforming in a Pd-based membrane reactor of shell and tube design

This work investigates numerically the characteristics of the two process, hydrogen separation and steam methane reforming (SMR), in a palladium-based (Inconel-supported Pd–Ag film) membrane reactor (MR) of porous reformer (30% Ni/Al2O3) shell and multi-tube design. Still parameters like reactor design and temperature, feed gas concentration and pressure, and flow configuration need more investigation to figure out their impact on hydrogen production rate at lower energy cost and minimum possible volume. This work targets optimization of reactor performance for higher hydrogen yield and coming up with a scalable optimized reactor design for industrial applications. First, an optimization study is performed under non-reforming (separation-only) conditions to optimize the MR design and operating parameters for higher hydrogen production. Then, the study is extended to consider hydrogen separation under SMR conditions to come up with a MR design for hydrogen production at the industrial scale. Hydrogen permeation is limited to small zone near the membrane surface with no effect of feed pressure, inlet gas temperature, and feed hydrogen concentration on widening such zone that necessitates reducing the pitch distance between membrane tubes below 22 mm. The results showed reduced hydrogen permeation rate under SMR conditions compared to the separation-only cases.

Investigation of film boiling over tandem arrangement of elliptical cylinders in vertical cross-flow of saturated liquid

The present study investigates the phenomenon of film boiling heat transfer for the tandem arrangement of elliptical heaters placed in cross-flow of saturated liquid (water) at near critical pressure conditions (P/Pc = 0.99), using the Eulerian approach-based volume of the fluid framework. The effect of vertical spacing between the heaters (pd = 7.5a to 12.5a), their aspect ratio (ψ = 0.4 to 1), degree of wall superheat (Jav/Prv = 0.6 to 1.8) and Reynolds number for liquid flow (Rel = 10 to 40) is investigated on the bubble departure dynamics and heat transfer characteristics. It is observed that the bubble departure size from the bottom heater has remained almost unchanged for all the situations whereas its departure frequency has increased upon an increase of Reynolds number and degree of superheat. The bubble size has varied significantly for the top elliptical heater and its departure frequency has increased with the decrease of aspect ratio and increase of pitch, Reynolds number and degree of superheat. The time-averaged heat transfer coefficient has increased upon an increase in pitch distance, aspect ratio, Reynolds number and degree of superheat, however, the rate of increase has diminished at a high degree of superheat.

FePt–BN granular HAMR media with high grain aspect ratio and high L1 ordering on corning LotusTM NXT glass

Fabricating highly ordered tall L10–FePt with a small grain pitch distance on a commercially available glass substrate is crucial to realize heat-assisted magnetic recording (HAMR) media for industrial manufacture. We have realized tall FePt grains surrounded by crystalized h–BN on Corning NXT™ glass deposited at elevated temperatures in the presence of radio frequency (RF) bias. In this paper, we discuss the effect of deposition temperature on the order parameter of L10–FePt–BN granular media. Well-isolated L10–FePt–BN granular media with a grain diameter of 6.5 nm and height of 11 nm is achieved. These films exhibit a high order parameter of 0.85 with a perpendicular coercivity of 35 kOe.

Numerical and analytical study of pinned column base plate connections

Gravity system column base plate connections are generally classified as pinned connections with no to minimal moment capacities. A low rotational stiffness value is recommended by the New Zealand Steel Structures Standard, NZS 3404, to represent pinned connections. However, numerous past research studies have shown that these so-call pinned connections possess significant rotational stiffness which could attract large moment demand and potentially lead to yielding of the column base. Furthermore, the constant axial load on the gravity column in conjunction with column base yielding could result in axial shortening of the column, which would significantly increase the cost and difficulty of post-earthquake rehabilitation. With the aim to minimize column base yielding and column axial shortening, a numerical parametric study was conducted to examine the influences of various parameters, including base plate thickness, anchor rod diameter, axial load magnitude, foundation depth and anchor rod pitch distance, on the connection behaviour. It was found that the applied axial load greatly affected the moment resistance as well as the rotational stiffness of the connection. Results also showed that the rotational stiffness of pinned column base plate connections was significantly higher than the value suggested in NZS 3404. An analytical model was developed and validated against numerical and experimental studies to predict moment-rotation response of pinned column base plate connections. Satisfactory results were observed.

Performance investigation of an all glass evacuated tube solar collector with an innovative heat exchanger design using TiO2-H2O nanofluids- an experimental study

ABSTRACT The objective of the current study is to experimentally analyze the thermal performance of an all-glass evacuated tube solar collector (ETSC) with an innovative heat exchanger design by employing TiO2-H2O nanofluid as a heat transmission fluid. Different higher volume concentration (v/c) of TiO2 nanoparticles, i.e. 0.83%, 0.9%, and 0.94% are examined to explore the impact of the nanofluids on the ETSC performance in comparison with only water based ETSC. An outdoor experimental investigation has been carried out using nanofluid at 0.6, 0.7 and 0.8 l/min volumetric rates of flow and its impact using serpentine copper tube coil having uniform pitch distance of 14.3 cm with aluminum fins attached on both side of coil having diameter 12 mm and thickness 1 mm, respectively. The study indicates that thermal performance of ETSC increases with the rise in volumetric flow rate with higher v/c of nanoparticles. For this condition, the temperature rise of water using nanofluid is higher than simple water-based ETSC system, recording an increase in outlet temperature by 4.21%. The maximum thermal efficiency obtained is 52.33% at 0.9% v/c and 0.8 l/min. A comparative assessment between the obtained results and some of the published results reveals that by using serpentine copper coil attached with aluminum fins, with higher concentrations of TiO2 nanoparticles and maintaining higher volumetric flow rate, thermal efficiency of ETSC can be much improved.

Study the effect of Pitch size When the number of rings of the second air gaps on the dispersion profile of Photonic Crystal Fibers

The need for a fibre optics working in the visible part of the electromagnetic spectrum has led to the development of new kind of fibre optics called photonic crystal fibre (PCF).In this paper we have investigate the effect of the pitch distance Λ as a function of the wavelength for a single mode PCF. The results has indicated that for (Nr=2 , MNr=1 , Λ=1.2 , d/Λ=0.5) this design has a dispersion of (-37ps/nm/km) at λ=0.8µm and a dispersion of (-30 ps /nm/km) at λ=1.31µm and a dispersion of( 1.10ps/nm/km) at λ= 1.55µm .This design has a flat dispersion for a wavelength range of (0.95 µm, in addition to that, this model has (3ZDW) in the dispersion curve. P

Towards an optimum pitch to chord ratio and establishing its scaling effects in low head Kaplan propellers

Notwithstanding the long historic journey of Kaplan turbines for hydropower generation, the inner design details like position of guide vane relative to runner, blade pitch to chord ratio amongst others are yet to be investigated in depth let alone being standardized. This dearth widens in small capacity hydropower plants. The current study chooses the blade pitch to chord as research theme to be investigated both experimentally and numerically on a medium-high specific speed Kaplan turbine. Three levels of study are envisaged for obtaining the optimum ratio. The first is the change of blade number with chord fixed, the second is fixing the blade number and changing the chord length and final level of keeping the ratio constant by varying the pitch and chord by identical proportion attempts to clarify the scaling effects. Optimum efficiency in the range of 78%–82% for ratios 1.2 to 2.2 are observed for smaller pitch, smaller chord condition. The scaling study at optimum ratio revealed that increasing the blade pitch distance causes the exit fluid deflection deteriorating the performance. The paper strongly recommends a wider pitch-chord ratio study in higher specific speed Kaplans to get standardized scaling effects with respect to size and achieve universality.

Computational flow and heat transfer study on impingement cooling in a turbine blade leading edge using an innovative convergent nozzles

The present paper discusses a detailed numerical study performed to investigate flow and heat transfer characteristics of impingement cooling of the leading edge of a HP gas turbine blade model. An array of innovative converging shape nozzles are used as jets which strike the surface to be cooled. A comprehensive study is presented investigating various parameters which effect impingement cooling. These parameters include varying Mach number of the flow as 0.2 to 0.8, converging ratio of the nozzle varied as 2 to 8 at two different minor diameters of 0.25–0.5 mm of the jet, pitch distance is changed from 3 to 5 mm, and inter-jet distance changed from 3 mm to 6 mm. Each parameter is independently scrutinized keeping other parameters constant. The results indicate the formation of primary stagnation region where Nusselt number augmentation is maximum compared to secondary stagnation region. Cross-flow effect plays a significant role in reducing peak values in the Nusselt number in the downstream region. Enhancement in peak Nusselt number value is greater for high values of Mach number of the flow, lower jet-to-target distances and the higher converging ratio at a lower value of jet diameter. Average Nusselt number is found to be higher for lower values of pitch distance.

Experimental study of fluid flow properties in spiral tube heat exchanger with varying insert shape over spiral tube profile

Experimental and computational analysis is carried out for analyzing the effect of different shapes of inserts. The inserts used are conical inserts, hemispherical shape insert, helical insert and these are mounted over cascaded spiral copper tube heat exchanger. The performance characteristics and fluid flow characteristics are studied for turbulent-counter flow and the fluid is water. Experimentation carried out for cold water at 304 K and hot water at 333 K and the rate of fluid flow for cold water inside spiral tube is 0.725 to 2.955 L/min. The hot water flows at 333 K with fluid rate of flow 4.025 L/min horizontally across outer shell. The comparative study of different shapes of insert with rate of fluid flow and Reynolds number is considered ranging from 4236 to18545. The study stated that the helical type insert gives promising and significant improvement by 18.5 % more than spiral tube without insert, 15.5 % more than conical insert and 11.5 % more than hemispherical shape insert for thermal performance under turbulent-counter flow. The minimum and maximum values obtained from the study for h htr , Nu, f, effectiveness N.T.U and ɳ tp varies from 1298.5 to 3541.6, 88.28–160, 0.0438–0.0306, 0.89–0.59, 2.51–1.24 and 2.41–1.31 respectively. The maximum optimum value is obtained for performance factor (ɳ tp ) is 1.51 for Reynolds number ranging 13,322 for helical insert of 2 mm diameter and 10 mm pitch distance.

A comparative surface evaluation of orthodontic mini-implants before and after en masse retraction-A SEM study.

To evaluate the changes in surface morphology of two different types of mini-implants after clinical en masse retraction using scanning electron microscopy. Fifty mini-implants of Dentos (Korea, Absoanchor, BH-1817-08) and Orlus (Korea, Yesanchor, C-1817) were inserted in patients in a split-mouth design who required en masse anterior retraction and absolute anchorage. Surface characteristics of mini-implants such as pitch (distance between consecutive threads), flank width (distance between root and crest), and taper were studied using scanning electron microscope (FEI nanosem450) before and after clinical use. Statistically significant difference (p value = 0.003) was found in a mean reduction of pitch dimension among the two groups with a mean difference of 25.000 μm. Also, a statistically significant difference was noted (p value = 0.001) in a mean reduction of flank width among Dentos implants as compared to Orlus implants. A statistically significant difference (p = 0.001) was seen in the mean reduction of taper dimension among Dentos group (0.0140 ± 0.02271) as compared to the Orlus group (0.0810 ± 0.05152). A marked reduction in surface morphology such as the pitch, flank width, and taper of both mini-implants after retrieval was observed. Dentos group of mini-implants displayed better dimensional stability post-retrieval as compared to the Orlus group of mini-implants. All the mini-screws showed milling defects in form of scratches on observation under scanning electron microscopy despite a smooth appearance to the naked eye.

Experimental investigation on low-velocity impact response of spherical core sandwich structure

In the present work, the low-velocity impact characteristics of the spherical core sandwich structures made of glass fibre reinforced plastic (GFRP) are tested at different strike velocities (3, 5, and 7 m/s). Four different types of core orientation, namely, regular, interlock, inverted, and stagger, are designed and fabricated by the hand-layup method. Vinyl ester resin and woven glass fibre fabrics are used as matrices and reinforcements, respectively. The diameter of the spherical core and the pitch distance is chosen as 16 mm and 32 mm, respectively. The impact behaviour of the novel spherical sandwich structures is examined based on the maximum contact force, energy absorption capacity, coefficient of restitution (COR), and damage behaviour. The Regular model shows enhanced energy absorption capacity with a specific absorbed energy of 0.092 J/(kg/m3) at 7 m/s impact velocity. Similarly the Interlock model shows good damage resistance. The typical failure patterns observed in the Interlock model at 3 m/s are matrix cracking (MC) and fibre breakage (FB), whereas, at 5 and 7 m/s impact velocities, the damage core crushing (C) is observed.

Numerical analysis of hybrid nanofluids in rectangular duct for thermal enhancement integrated with polygonal rib

The research was carried out to investigate the augmentation of thermal performances in the Solar Water Heater (SWH) by implementing rough surfaces in the absorber plate and Nanofluid considered a working fluid. A hybrid nanofluid Al2O3 / Cu O (60:40) was taken as a working fluid and compared with Al2O3 nanofluid and base fluid to ascertain the augmentation of convective heat transfer in SWH. The forward and backward trapezoidal shapes of the rib were employed in the absorber plate at relative pitch distances p/e = 10 at relative roughness height e/d = 0.06. Average Nusselt number (Nu), and friction factor (f) were investigated at Reynolds numbers ranging from 4000 to 18000. Turbulent model k-∊ was selected to examine the vortex generated in the fluid flow direction owing to the rough surface. The result reveals that hybrid nanofluid with backward trapezoidal rib at p/e = 10 has produced a higher Nusselt number 95.6 at Reynolds number 18,000 than other ribs and fluid.

Numerical investigation into heat transfer augmentation in a square minichannel heat sink using butterfly inserts

Heat transfer augmentation in a square minichannel heat sink through introduction of various butterfly insert configurations is numerically investigated for a range of Reynolds numbers (200 – 900). The present study also examines the individual effects of insert, pitch of the insert, and perforations in the wings of the butterfly insert on the thermohydraulic performance of minichannel heat sinks. Incorporating any kind of insert in a typical square minichannel is found to have a positive influence on the overall thermohydraulic performance, yielding performance evaluation criteria consistently over unity for the whole range of tested Reynolds numbers. The effect of pitch is tested for unperforated inserts, wherein a reduction of pitch distance from 10 mm to 5 mm is found to increase heat transfer performance by 15.08 - 46.39% for the studied range of Reynolds numbers. Perforations in the wings of butterfly inserts are found to result in a reduction of friction factor, with a 4.01 – 20.78% decrease, when compared with an unperforated insert having an identical pitch. However, this reduction is achieved at the cost of a lower heat transfer performance (5.07 – 16.17%). Therefore, unperforated butterfly inserts are deemed to be superior in terms of the overall thermohydraulic enhancement. In all enhanced minichannel configurations, a redistribution of velocity and temperature fields due to the formation of a primary vortex pair and thinning of thermal boundary layers due to a second pair of secondary vortices are thought to be the major contributors behind the observed thermohydraulic enhancement. • Introduction of a butterfly insert with 10 mm pitch is found to enhance heat transfer performance in MCHS by 42.02% to 109.31% for the tested range of Reynolds numbers. • A reduction in pitch from 10 mm to 5 mm in an MCHS with unperforated butterfly inserts is observed to yield an augmentation of average Nusselt number by 15.08% to 46.39% for the studied range of Reynolds numbers. • Perforation on insert wings is found produce a reduced enhancement in average Nusselt number, i.e., 5.07%–16.17%, for the investigated range of Reynolds numbers. • Observed thinning and disruption of thermal boundary layers and enhanced fluid mixing at the central region of the minichannel due to a pair of primary vortices are thought to be the major reasons for enhanced thermal performance. • A maximum performance evaluation criterion of 1.66 is observed for the case of unperforated butterfly inserts with 5 mm pitch at a Reynolds number of 900.

Optimization of Resistance Spot Welding Parameters in a Shop Floor Environment to Achieve Desired Spot Size in Low Carbon Steel Sheet

Resistance Spot Welding (RSW) is widely employed in automotive, electronics, furniture, Coach building and package industries. Although various spot weld methods, such as Friction Stir Spot Welding, MIG Spot welding, Laser Spot welding and Ultrasonic Spot welding are in use, Resistance spot welding is a versatile and easy method to adopt in simple fabrication shop. It is well known that various factors significantly influence the spot size and its quality. Designers, while selecting RSW process are particularly interested in fixing the appropriate spot size and pitch distance for a specific application. Against the above background, this study has been carried out to arrive at desired spot size by varying the parameters using a simple shop-floor spot welder which is readily available in any fabrication shop. Three levels of power input, three levels of welding current time and many levels of weld cycle time have been adopted for 2mm thick low carbon steel sheet of IS 513 grade. A novel technique has been developed to apply adequate torque to shear the spot weld joint without any damage or distortion. Spot size has been determined by using vernier and profile projector. The nugget quality has been examined using optical microscope at different magnifications. The bond strength of the spot weld has been determined by tensile shear test. By adopting this simple technique, it is possible to achieve desired spot size which is defect free and having excellent penetration. Keywords: Low carbon steel sheet, Resistance Spot welding, Nugget size, welding parameters, macro & micro examination.

Numerical investigation of various twisted tapes enhancing a circular microchannel heat sink performance

The continuous power increase and miniaturization of modern electronics require increasingly effective thermal management systems. The thermo-hydraulic performance of water-cooled L×L square-base silicon microchannel heat sinks is investigated by a conjugate heat transfer and computational fluid dynamics model over the Reynolds number range 100 to 500. Water at a constant inlet temperature of 298 K runs through 33 parallel tubes, extracting heat from the bottom wall that has a 100 W/cm2 constant heat flux input. Hydro-thermal performance-enhancing tape inserts are numerically tested featuring (i) radial gaps between the tape and the tube, (ii) tape twist with axial pitch distances of ∞, L/2, or L/4, (iii) zero, one, or two 90-degree angular steps between consecutive tape segments, (iv) alternating clockwise and anti-clockwise consecutive twisted tape segments, and combinations of these features. The radial gaps produce both a hydraulic and a thermal performance loss. All combinations of tape twist, angular steps, and twist direction reversal produced better thermal performance gains to hydraulic loss trade-offs than the baseline microchannel configuration with no tape. The microchannel heat sinks with four L/4 alternating pitch consecutive helical tape segments provided the lowest bottom wall average temperature, 16.13 K below that with not tape, at the same Reynolds number of 500. This predicted temperature drop is a significant achievement towards conditioning electronic components so they may be longer-lasting, use less energy, and have a reduced environmental impact.

Investigation of fluid flow and heat transfer in a narrow channel with micro barchan-dune-shaped humps

• A bionic heat sink with micro barchan-dune-shaped humps is proposed. • The micro dune can reinitialize the boundary layer by inducing a secondary flow. • The micro dune generally outperforms traditional fins in overall heat transfer performance. This paper proposes an innovative bionic heat sink with micro barchan-dune-shaped humps for improving the flow and heat transfer performance of the smooth narrow channel. The effects of the Reynolds number of the main flow ( Re ) and pitch distance of the dune array ( P ) on the thermal-hydraulic performance are investigated. In this work, the air is the working flow. The Reynolds number range is considered to cover the regimes of laminar, transitional, and turbulent, Re = 860–6,050, and the pitch distance ( P ) equals 8, 12, and 16 mm. The results show that the micro barchan-dune-shaped hump can induce a secondary flow downstream of the slip face and enhance the local heat transfer performance. For the multi-dune models, the case with P = 16 mm provides the highest overall thermal performance parameter ( η ). The η value decreases monotonically with decreasing P in the considered range. In addition, compared with other micro pin fin shapes (including the hexagonal cylinder, square cylinder, and triangular cylinder), the η of the barchan dune shape is almost identical to that of the hexagonal cylinder and exceeds the other two shapes by more than 20%.

Simulation of structure and power generation for Self-Compacting concrete hollow slab solar pavement with micro photovoltaic array

To explore new solar pavements, a self-compacting concrete hollow slab solar pavement based on a micro photovoltaic array was proposed. The hollow slab solar pavement is composed of three layers: a surface transparent protection slab, a middle micro photovoltaic array, and a bottom concrete base slab. Using ANSYS software and PVsyst software, through the 3D finite element numerical simulation and power generation simulation of the pavement structure, based on orthogonal experimental design and single-factor sensitivity analysis, the structure size of the hollow slab and the layout mode of the micro photovoltaic array were optimized. Then, the optimal hollow slab model was determined. The results show that the optimal size of the hollow slab is 1000 × 1000 × 250 mm; the tilt, azimuth, pitch and edge distance of the solar cells in the best layout mode of the micro photovoltaic array are 18°, 0°, 45 mm and 65 mm, respectively; the power generation capacity in the first year is 140.697 kWh. The life cycle economic analysis indicates that the increased cost can be recovered through the power generation income after 10.2 years, and 1 km of two-way four-lane pavement could reduce by 2.15 × 107 kg of CO2 emissions, with good economic, social, and environmental benefits.

Influence of secondary flow angle and pin fin on hydro-thermal evaluation of double outlet serpentine mini-channel heat sink

Achieving high processing speed in electronic components combined with large amount of generated heat, this heat removed by heat sink. For extreme heat generated, a mini-channel liquid cooled heat sink is used. The aims of the present study are to enhance the efficiency of the serpentine mini-channel heat sink and to uniformly temperature distribute. To achieve that, several variables were studied, namely the double outlet, the secondary flow channel with different backwards angles (45°, 53°, 61°) and finally the combination of secondary flow with pin fin at different pitch distances (5d, 6d, 7d). Ansys Fluent 2020 R2 software was utilized to extract the numerical results. The two models were fabricated and tested experimentally, namely the Basic model and the optimum model (model F), to validate the numerical results. The results of validation showed a good agreement. The results show that the use of a double outlet serpentine mini channel heat sink leads to an increase in overall performance to 1.47 and a lower maximum base temperature. With an 8.7% increase in overall performance and an even lower base temperature, the secondary flow backward angle of 53° (model C) outperforms the other two angles. However, combining the secondary flow with the pin fin enhances the heat sink both thermally and hydraulically. The model F displays the maximum performance with a 1.79 and a Nusselt number of 9.64% as compared to the Basic model.