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Power plants are part of industrial facilities used to produce and generate electricity from various power sources; one of those is PLTGU (Pembangkit Listrik Tenaga Gas dan Uap or Gas and Steam Power Plant). PLTGU is a combined cycle between PLTG and PLTU. It is necessary to achieve a high-capacity target for the PLTGU to increase the generator's efficiency. One way to increase the efficiency of gas and steam power plants is by optimizing heat transfer in the Heat Recovery Steam Generator (HRSG). HRSG has several modules such as superheater, evaporator, economizer, and preheater. One that plays an essential role in absorbed high-temperature steam from the gas turbine is the superheater. The function of the superheater is to utilize the heat from the flue gas to reheat the fluid needed for the steam turbine. In this research, improvements of superheater were made with several fin variations at HRSG PLTGU. Variable of superheater refer to data on the layout of the HRSG PLTGU. Autodesk Inventor is used to modeling flue gas domain, tube, and fin. Additional of the fin has the purpose of optimizing heat transfer distribution in steam through a tube, such as an outlet temperature and efficiency of steam in tube superheater. The use of CFD (Computational Fluid Dynamic) with ANSYS Fluent could use to determine the temperature distribution of the superheater. The most optimal efficiency and outlet temperature of variation fin is the annular fin variation compared to the rectangular and straight fin variations.

Electromagnetic particle-in-cell (PIC) codes are widely used to perform computer simulations of a variety of physical systems, including fusion plasmas, astrophysical plasmas, plasma wakefield particle accelerators, and secondary photon sources driven by ultra-intense lasers. In a PIC code, Maxwell's equations are solved on a grid with a numerical method of choice. This article focuses on pseudo-spectral analytical time-domain (PSATD) algorithms and presents a novel hybrid PSATD PIC scheme that combines the respective advantages of standard nodal and staggered methods. The novelty of the hybrid scheme consists in using finite-order centering of grid quantities between nodal and staggered grids, in order to combine the solution of Maxwell's equations on a staggered grid with the deposition of charges and currents and the gathering of electromagnetic forces on a nodal grid. The correctness and performance of the novel hybrid scheme are assessed by means of numerical tests that employ different classes of PSATD equations in a variety of physical scenarios, ranging from the modeling of electron-positron pair creation in vacuum to the simulation of laser-driven and particle beam-driven plasma wakefield acceleration. It is shown that the novel hybrid scheme offers significant numerical and computational advantages, compared to purely nodal or staggered methods, for all the test cases presented.

Flowering plants display unsurpassed diversity in the morphology of their reproductive structures, including the stamens. Stamens within a flower are usually akin in appearance, however some species possess two, or occasionally three, structurally distinct types that often differ in reproductive function. This peculiar morphological differentiation of stamens and anthers within a flower is referred to as heteranthery. It occurs in at least 20 families distributed among 12 orders including Commelinaceae, Fabaceae, Lythraceae, Melastomaceae, etc. Functional significance of this feature has also been elaborated in several species. Genus Crotalaria of family Fabaceae is a classical example displaying this mechanism. Present work carried out on two species of genus Crotalaria i.e., C. medicaginea and C. mysorensis, forming natural population at an altitude of 426–1015 m a.s.l. in subtropical regimes of Northwestern Himalayas is aimed to address relative functional significance of this dimorphism. The dimorphism of anthers that includes shape, size, dehiscence time as well as size of pollen is associated with staggered presentation of pollen in both the species. As expected, this aids in delayed selfing and assurance of seed set. However, while heteranthery plays extremely significant role in the reproductive success of C. mysorensis, extent of contribution is relatively much lower in C. medicaginea. [ABSTRACT FROM AUTHOR]

The fatigue damage caused by flow-induced vibration (FIV) is one of the major concerns for multiple cylindrical structures in many engineering applications. The FIV suppression is of great importance for the security of many cylindrical structures. Many active and passive control methods have been employed for the vibration suppression of an isolated cylinder undergoing vortex-induced vibrations (VIV). The FIV suppression methods are mainly extended to the multiple cylinders from the vibration control of the isolated cylinder. Due to the mutual interference between the multiple cylinders, the FIV mechanism is more complex than the VIV mechanism, which makes a great challenge for the FIV suppression. Some efforts have been devoted to vibration suppression of multiple cylinder systems undergoing FIV over the past two decades. The control methods, such as helical strakes, splitter plates, control rods and flexible sheets, are not always effective, depending on many influence factors, such as the spacing ratio, the arrangement geometrical shape, the flow velocity and the parameters of the vibration control devices. The FIV response, hydrodynamic features and wake patterns of the multiple cylinders equipped with vibration control devices are reviewed and summarized. The FIV suppression efficiency of the vibration control methods are analyzed and compared considering different influence factors. Further research on the FIV suppression of multiple cylinders is suggested to provide insight for the development of FIV control methods and promote engineering applications of FIV control methods. [ABSTRACT FROM AUTHOR]

Channelization of energy improves the ability of a thermal management system. Pin fins are commercially used in various heat sink applications due to their optimum performance. The present study evaluates a pin fin heat sink (PFHS) using an entropy generation approach. Inline and staggered pin fins with wings are compared with the conventional pin fins for the pin–fin pitch ratio (PFPR) of 2–4 and the wing length ratio (WLR) of 0.2–0.6 in the Reynolds number range of 6800 to 15,100. The total entropy generation decreases with the increase in PFPR and the decrease in WLR. The minimum thermal and frictional entropy generation corresponds to the PFPR of 4 for both inline and staggered pin–fin arrangements. The maximum and minimum total entropy generation are found at the PFPR of 2 (for inline) and 4 (for staggered), respectively. The optimum value of total entropy generation is found for the PFPR of 4 and WLR of 0.2 in both arrangements (inline and staggered). [ABSTRACT FROM AUTHOR]

This paper presents a numerical emulation study of heat transmission through tube banks in three-dimensions. Staggered configuration is displayed by fluid dynamics using computer programs (CFD) software (ANSYS fluent). The computer model is used to predict the values of the Nusselt numberwhen changing the values of heat flux and longitudinal pitch. The longitudinal pitch (SL/D) of 1.3, 1.8, and 2.4 mm. The transverse pitch (ST/D) of 1.5 mm, and also considered Reynolds numbers 10000, 13000, 17000, and 190000. The staggered configuration of the tube bundle is demonstrated to investigate the impact of this arrangement on the heat transmission rate from the tubes. The gotten results indicate that the rate of heat transmission increases with decreases in the longitudinal spacing (SL). As the longitudinal spacing (SL) increases to about 44% the Nusselt number is slightly decreased by about 9%. The coefficient of heat transmission, Nusselt number, and the heat transmission data obtained from (CFD) Compared to previous research results, there is a decent agreement originating after comparison. [ABSTRACT FROM AUTHOR]

Telecommunication systems have become a critical part of society which enables connectivity to many essential and trivial services. Consequently, telecommunication equipment is housed in cabinets to protect the electronics from a variety of hazards; one of which is temperature-related failure. Current practices use a notable amount of power for the thermal management of telecommunication cabinets which can be reduced by considering alternative methods of cooling. In this paper, experiments were carried out to investigate the effectiveness of different internal mounting configurations of electronic components on the thermal performance of a telecommunication cabinet. The investigation tested inclinations (0–90°), different staggered offsets (0–50 mm), changing stream-wise spacing (29–108 mm), and fan speed (with a Reynolds number in the range of 1604 to 5539). The experimental study revealed that heat transfer was enhanced by 9.99 % by altering component inclination to 90°, 25.90% by increasing stream-wise spacing from 29 mm to 108 mm, and 36.02% by increasing the Reynolds number from 1604 to 5539. However, the staggered arrangement of internal components decreased N u by 3.26% for the natural convection condition but increased by 5.69% for the forced convection condition over the tested range and increasing the centre offset of the staggered components with respect to the cabinet did not influence N u in any significant manner. Natural convection and forced convection also had notable influence on the heat transfer rate. Hence it was seen that alternative internal configurations positively influence heat transfer in telecommunication cabinets for the cases studied. [ABSTRACT FROM AUTHOR]

Background: We investigated if staggering sugammadex would reduce postoperative complications (with special regards to cough), compared to single dose of sugammadex or standard neostigmine in patients undergoing thyroidectomy surgery. Methods: A 36 adult patients aged 21-60 years old, ASA I and II undergoing thyroidectomy surgery, were randomized into 3 groups; (S group) that received 2 mg/kg sugammadex as single bolus, (SS group) that received sugammadex 2 mg/kg in a staggered dose of 1 mg/kg prior to extubation and another 1 mg/kg immediately after extubation and (N group) that received 0.05 mg/kg neostigmine combined with 0.02 mg/kg atropine. Results: Cough was absent in (SS) group. The percent of cough was 33% in S group and about 67 % in N group. Patients of (SS) and (S) groups had significant shorter recovery time and extubation time. Patients of (N) group showed significant increase in HR and SBP at 5 min after reversal compared to both (SS) and (S) groups, but no significant difference in DBP between all groups. There was no significant difference between all groups regarding postoperative complications other than cough . Conclusions: Staggered sugammadex reduces significantly risks for cough on emergence when compared to 2mg single bolus sugammadex. In addition, staggered sugammadex-as well as bolus sugammadex-has better recovery and more stable hemodynamics when compared to neostigmine. [ABSTRACT FROM AUTHOR]

The computational analysis of fiber network fracture is an emerging field with application to paper, rubber-like materials, hydrogels, soft biological tissue, and composites. Fiber networks are often described as probabilistic structures of interacting one-dimensional elements, such as truss-bars and beams. Failure may then be modeled as strong discontinuities in the displacement field that are directly embedded within the structural finite elements. As for other strain-softening materials, the tangent stiffness matrix can be non-positive definite, which diminishes the robustness of the solution of the coupled (monolithic) two-field problem. Its uncoupling, and thus the use of a staggered solution method where the field variables are solved alternatingly, avoids such difficulties and results in a stable, but sub-optimally converging solution method. In the present work, we evaluate the staggered against the monolithic solution approach and assess their computational performance in the analysis of fiber network failure. We then propose a hybrid solution technique that optimizes the performance and robustness of the computational analysis. It represents a matrix regularization technique that retains a positive definite element stiffness matrix while approaching the tangent stiffness matrix of the monolithic problem. Given the problems investigated in this work, the hybrid solution approach is up to 30 times faster than the staggered approach, where its superiority is most pronounced at large loading increments. The approach is general and may also accelerate the computational analysis of other failure problems. [ABSTRACT FROM AUTHOR]

A unified framework for an impromptu switching between the coupled (i.e., the monolithic), the staggered, and the uncoupled solution strategies for the phase-field based computations of material fracture is presented. As a model problem, a 2d quasi-brittle solid phase-field formulation, which is based on the tension-compression split energy functional, is chosen. In order to fit within the proposed framework, the classical staggered approach is reformulated as a loop of uncoupled monolithic steps that we call modified-staggered. Numerical examples show that an automatic switching between the coupled and the modified-staggered solution methods (when the former fails) may shorten the computational times (compared to the pure staggered approach) for an order of magnitude. [ABSTRACT FROM AUTHOR]

• Forced convection heat transfer in pin fin plates of different geometries with equal surface area. • Triangle staggered pin plate heat exchangers reached the maximum Nu numbers. • The staggered configuration of the pin fin plates demonstrated high performance in heat transfer. • The highest-pressure drop was in triangular and elliptical pin plate heat exchangers. In this study, the effects of forced convection heat transfer on the surfaces of pin plate heat exchangers with different geometries modified to the heat exchanger form were experimentally investigated. A total of 8 pin fin plate heat exchangers, four of which are staggered and the other four are in-line, were used in the experiments. The heat transfer surface areas of the pin plate heat exchangers are produced equally. The only difference is their geometry, which is produced in four different shapes: triangle, circle, ellipse and square. The experiments were carried out at air velocities of 1 to 6 m/s with 1 m/s increments and at 10 W and 50 W input powers with 10 W increments. The staggered configuration of the pin fin plates demonstrated high performance in heat transfer. The study found that heat exchangers with cornerless pin plates have lower heat transfer compared to those with cornered pin plates. The pressure drops increased as the velocity of the coolant air increased, and the highest-pressure drop was observed in staggered triangular and elliptical pin plate heat exchangers. This research is considered innovative as it involves an experimental comparison between staggered and in-line pin plate heat exchangers in four different geometries, all with equal surface area. [ABSTRACT FROM AUTHOR]

Based on the manually sorted data of first secretaries in poor villages and the micro data of rural household income, this paper analyzes the policy effect of resident Party official in poor villages on getting rich and increasing income. The research results of this paper are as follows. Firstly, the policy of Party officials in poor villages has significantly increased the average income of rural households, especially for the poor households. Secondly, the income growth effect mainly refers to the improvement of agricultural output and labor income, which reflects the effectiveness of poverty alleviation by stimulating the poor to get out of poverty by themselves. Thirdly, the policy of Party officials in poor village has increased poor households' government subsidy income, and helps to greatly improve the agricultural income of non-poor households. There may be poverty identification bias and elite capture phenomenon in the implementation process. Further analysis shows that the Communist Party of China pays more attention to the policy of resident first secretaries in poor areas, and the dispatch of higher-level resident officials is conducive to achieving better poverty alleviation benefits. [ABSTRACT FROM AUTHOR]

The present experimental paper is officiated to study the heat characteristics and performance of air flow through a square cross-sectional heated channel under natural heat convection conditions. The influence of baffles arrangement and perforated baffles on the rate of heat transfer through a channel are studied. Four cases of a heated channels are studied, one is a plain channel and other three channels with a baffle namely, three inline baffles, three staggered baffles and three staggered perforated baffles arrangements. The outer tested channels surfaces are electrically heated with a constant surface heat flux condition. All tested channels are fabricated by cold forming with constant dimensions using aluminum plate has thickness of 1.0 mm. The heat performance is assessed for all tested channels. The results of present paper are approved than the available data in the previous paper and a good convergence are noticed. Obtained experimental results appear that a three staggered perforated baffles arrangement is a best selection as it improves heat transfer rate in expression of Nusselt number, it higher about 22% to 27% than that the plain channel for same conditions. [ABSTRACT FROM AUTHOR]

This paper proposes two high-resolution, wide-swath synthetic aperture radar (SAR) acquisition modes for ship monitoring that tolerate ambiguities and do not require digital beamforming. Both modes, referred to as the low pulse repetition frequency (PRF) and the staggered (high PRF) ambiguous modes, make use of a wide elevation beam, which can be obtained by phase tapering. The first mode is a conventional stripmap mode with a PRF much lower than the nominal Doppler bandwidth, allowing for the imaging of a large swath, because the ships' azimuth ambiguities can be recognized as they appear at known positions. The second mode exploits a continuous variation of the pulse repetition interval, with a mean PRF greater than the nominal Doppler bandwidth as the range ambiguities of the ships are smeared and are unlikely to determine false alarms. Both modes are thought to operate in open sea surveillance, monitoring Exclusive Economic Zones or international waters. Examples of implementation of both modes for TerraSAR-X show that ground swaths of 120 km or 240 km can be mapped with 2 m2 resolution, ensuring outstanding detection performance even for small ships. The importance of resolution over noise and ambiguity level was highlighted by a comparison with ScanSAR modes that image comparable swaths with better noise and ambiguity levels but coarser resolutions. [ABSTRACT FROM AUTHOR]

Cross-flow boiling in horizontal tube bundles occurs in kettle type evaporators. Convective heat transfer due to the motion of vapor bubbles is an important factor for boiling heat transfer in the evaporator under low heat flux conditions. To clarify the liquid agitation effect on heat transfer, the local heat transfer around a tube in in-line and staggered tube bundles was investigated in two-phase flows under adiabatic and atmospheric pressure conditions. Air and tap water were used as the working fluids. The test section was a vertical duct with inner dimensions of 90 × 90 mm2. In-line and staggered tube bundles each containing eight rows and five columns, were used as test sections. For both bundles, the tube diameter, d, was 18 mm, and the tube pitch, p, was 22.5 mm (p/d = 1.25). The local heat transfer had the highest values around θ = ± 90° where the liquid velocities were high in single-phase, bubbly and intermittent flows for both in-line and staggered arrays. A significant improvement in the heat transfer caused by the bubble motion was present for the in-line array as compared to the staggered array. Owing to the fluctuation of the liquid velocity, the heat transfer coefficient fluctuated significantly under intermittent flow conditions. In the bubbly flow at p/d = 1.25, the average heat transfer coefficient around a tube for the in-line array was higher than that for the staggered array. In contrast, the heat transfer coefficient of the staggered array was high under intermittent flow at a lower gas flow rate. This tendency is different from the results at p/d = 1.5. With a decrease in the relative size between the bubble diameter and the tube gap, there was a high improvement in the heat transfer coefficient due to the liquid agitation in the bubbly flow.

Thermoacoustic devices require heat exchangers with oscillating flow, but there is currently no viable design approach for them. A heat exchanger with a staggered structure can efficiently improve the velocity disturbance and promote heat transfer in steady flow. The flow and heat transfer characteristics of a standing-wave thermoacoustic refrigerator and an ambient heat exchanger with staggered parallel plates under the oscillating flow condition are investigated in this study, primarily focusing on the geometric influences and differences between staggered and non-staggered (continuous) arrangements. The CFD simulation is a mainstream tool for the numerical simulation of complex thermoacoustic phenomena. The flow field around the stack and heat exchanger plate is simulated by introducing the dynamic mesh boundary conditions. Through numerical simulation, the flow field characteristics of non-linear vortices generation around the heat exchanger are presented. By changing the staggered column number in the ambient heat exchanger, it is observed that the larger the column number of staggered parallel plates, the more significant the refrigeration effect through the thermoacoustic effect. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to determine the safety and the clinical outcome of simultaneous, bilateral, and staged bilateral total knee arthroplasty (TKA) performed by a single surgeon at one academic institute., Methods: We prospectively followed and retrospectively compared the results of 7,155 patients (14,310 knees) who had simultaneous bilateral TKA, 6,671 patients (13,342 knees) who had staggered bilateral TKA, and 4,501 patients (9,002 knees) who had staged bilateral TKA. The mean age of the patients was 67, 65, and 69 years, respectively. The mean follow-up was 15.5, 15.3, and 16.1 years, respectively. The prevalence of mortality and complications were assessed in each group. In addition, patients were assessed clinically and radiographically at each follow-up., Results: The mortality rate (14 patients, 0.2%) of the patients who underwent simultaneous bilateral TKA was similar to those who underwent staggered bilateral TKA (19 patients, 0.3%) and those who underwent staged bilateral TKA (18 patients, 0.4%) (P > 0.05). The major complication (except death) rate (0.8, 0.5, and 0.4%, respectively) and the minor complication rate (20.7, 19, and 19.6%, respectively) were not significantly different among the three groups (P > 0.05). There was no significant difference in the clinical outcomes, radiographic results, revision rate, or survivorship of TKA implants among the three groups (P > 0.05). Transfusion requirements were different among the three groups (10% in the simultaneous bilateral TKA group, 12% in the staggered bilateral TKA group, and 2% in the staged bilateral TKA group)., Conclusions: We found no significant differences among the simultaneous, staggered, and staged bilateral TKA groups, with regard to the mortality, major complication, minor complication, and revision rates; the survival of TKA implants; and clinical and radiographic results after a mean follow-up of 15.5, 15.3, and 16.1 years, respectively., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The article presents the evolution of a novel configuration of tube placements in a shell and tube heat exchanger (HX). A CFD analysis on a double cross flow arrangement of tubes reveals improved mixing of the shell-fluid which is expected to increase heat transfer. This arrangement was modified for easier manufacture and maintenance, which led to the hybrid double cross flow (HDCF) arrangement. Experiments were carried out in the HDCFHX, for parallel and counter flows, to compare its performance against the conventional staggered arrangement. The HDCFHX comprises composite bundles of three and four tubes. The three-tube bundle is arranged in a staggered manner to themselves and orthogonal to the four-tube bundle. Ambient air at of 32 °C was used as the shell-fluid for Reynolds number ranging from 500 to 1000, for a fixed flow rate of 0.6 kg/min of water entering the tubes at 85 °C. This arrangement was observed to enhance the heat transfer with relatively lesser increase in pressure drop. The HDCFHX gave a significant improvement in heat transfer rate per pressure drop of 17 % to 38 %, vis-à-vis the conventional staggered arrangement in the parallel mode. The counter flow mode overly exhibited a similar trend, wherein the increase in this ratio varied from 8.5 % to 27.5 %. [ABSTRACT FROM AUTHOR]

In field practices, helical soil nails are installed in groups with staggered or uniform spacing. However, among the few prevalent literature on helical soil nails, studies regarding the group effect of helical soil nails are rare. Thus, to evaluate and better comprehend the behavior of helical soil nails in the group, an experimental investigation is conducted on a single and group of helical soil nails in the sand. The installation and pullout characteristics are evaluated under varying surcharge pressures and inclinations of 0°, 5°, 10°, 15°, 20°, 25°, and 30° with horizontal. During installation, the soil disturbances are also examined in terms of the installation disturbance factor (IDF). The group behavior is studied under two different configurations of staggered and uniform spacing. The earth pressures, torsional strains, and axial strains developed are also investigated. The test results suggest an optimized inclination range between 10° and 25° with horizontal showing low average IDF of 0.76, high torsional and axial strains. Helical soil nail group with staggered spacing revealed higher group efficiency, pullout resistance, and smaller installation torque in comparison to the group with uniform spacing. Also for uniform spacing, negative earth pressures along with large torsional strains and axial strains are observed. [ABSTRACT FROM AUTHOR]

This study focuses on comparison of in-line and staggered arrangements of circular micro-pin fins (MPF) in a rectangular micro-channel with the dimensions (l′ × w′ × h′) of 0.5 × 1.5 × 0.1 mm3. The height (H) and diameter (D) of the MPFs are both 0.1 mm. Two horizontal (SL) and vertical (ST) distances of 0.15 and 0.3 mm are considered with each type of arrangement, which results in four in-line and four staggered configurations. The simulations are run at five Reynolds numbers (Re) between 20 and 150, and a constant heat flux (HF) of 30 W cm−2 was applied through the bottom surface of the MHS as well as the liquid interacting surfaces of MPFs. The results are analyzed using four evaluative parameters, namely pressure drop, friction factor (FF), Nusselt number (Nu) and thermal–hydraulic performance index (TPI). These parameters were significantly affected by the wake length behind MPFs. In cases with a large horizontal pitch ratio (SL/D = 3), the wake length behind all columns (except the last one) could extend more (up to 2D) which in cases with the in-line arrangement typically resulted in higher pressure drop and FF (up to 10%) compared to similar cases with SL/D = 1.5. In cases with ST/D = 3, the larger available cross section among MPFs typically resulted in lower pressure drop (up to 36%) and Nu (up to 8%) compared to similar cases with ST/D = 1.5. With the same SL/D and ST/D, staggered arrangements generally had higher pressure drop, FF and Nu (up to 56, 39 and 9%, respectively) compared to similar in-line arrangements. Finally, the best TPI was attained with staggered arrangements with ST/D = 1.5 with 10% higher TPI compared to the reference case. [ABSTRACT FROM AUTHOR]

This numerical investigation presents the effects of the position of baffles in the shape of a circle’s segment placed inside a circular channel to improve the thermal and flow performance of a solar air heater. Three different baffles’ positions with Reynolds number varying between 10,000 to 50,000 were investigated computationally. The k-omega SST model was used for solving the governing equations. Air was taken as the working fluid. Three pitch ratios (Y = 3, 4, and 5) were considered, while the height of the baffles remained fixed. The result showed an enhancement in Nusselt number, friction factor, j-factor, and thermal performance factor. Staggered exit-length baffles showed maximum enhancement in heat transfer and pressure drop, while inline inlet-length baffles showed the least enhancement. For a pitch ratio of Y = 3.0, the enhancement in all parameters was the highest, while for Y = 5.0, the enhancement in all parameters was the least. The highest thermal performance factor of 1.6 was found for SEL at Y = 3.0.

Highlights • Experimental tests were performed to study the composite joints behaviors. • 3D finite element model was developed and validated with experimental works. • The staggered bolts arrangement, was studied along with several effective parameters. • Results such as, the stiffness, load transfer and stress concentration were discussed. • Staggered patterns produce horizontal forces that could cause additional cracks. Abstract Although the staggered arrangement in bolted connections can offer an efficient area usage especially for narrow members, it has the most complex stress fields. In this paper, experimental tests were performed to identify the initial stiffness of the bolted staggered joints. A 3D finite element model was developed to analyze single and double lapped bolted composite plates. The current modeling technique was validated by comparing its results against earlier experimental and numerical findings. Different bolt arrangements, including the staggered arrangement, were examined and combined with other parameters such as number of bolts, clamping force, and friction coefficient. Experimental tests showed that the double lapped joints have a higher stiffness than that of the single lapped joints. The numerical results showed that in the absence of clamping force, part of the load was transferred by friction due to the effect of secondary stresses, which can be increased by increasing the friction coefficient. Furthermore, the staggered patterns produced horizontal forces that could cause cracks in the composite material if it was not taken into consideration during the composite laminates design. [ABSTRACT FROM AUTHOR]

Finite-difference (FD) methods are widely used in seismic forward modeling owing to their computational efficiency but are not readily applicable to irregular topographies. Thus, several FD methods based on the transformation to curvilinear coordinates using body-fitted grids have been proposed, e.g., stand staggered grid (SSG) with interpolation, nonstaggered grid, rotated staggered grid (RSG), and fully staggered. The FD based on the RSG is somewhat superior to others because it satisfies the spatial distribution of the wave equation without additional memory and computational requirements; furthermore, it is simpler to implement. We use the RSG FD method to transform the firstorder stress-velocity equation in the curvilinear coordinates system and introduce the highprecision adaptive, unilateral mimetic finite-difference (UMFD) method to process the freeboundary conditions of an irregular surface. The numerical results suggest that the precision of the solution is higher than that of the vacuum formalism. When the minimum wavelength is low, UMFD avoids the surface wave dispersion. We compare FD methods based on RSG, SEM, and nonstaggered grid and infer that all simulation results are consistent but the computational efficiency of the RSG FD method is higher than the rest. [ABSTRACT FROM AUTHOR]

Electroactive polymers such as dielectric elastomers (DEs) have attracted significant attention in recent years. Computational techniques to solve the coupled electromechanical system of equations for this class of materials have universally centered around fully coupled monolithic formulations, which while generating good accuracy requires significant computational expense. However, this has significantly hindered the ability to solve large scale, fully three-dimensional problems involving complex deformations and electromechanical instabilities of DEs. In this work, we provide theoretical basis for the effectiveness and accuracy of staggered explicit–implicit finite element formulations for this class of electromechanically coupled materials, and elicit the simplicity of the resulting staggered formulation. We demonstrate the stability and accuracy of the staggered approach by solving complex electromechanically coupled problems involving electroactive polymers, where we focus on problems involving electromechanical instabilities such as creasing, wrinkling, and bursting drops. In all examples, essentially identical results to the fully monolithic solution are obtained, showing the accuracy of the staggered approach at a significantly reduced computational cost. [ABSTRACT FROM AUTHOR]

A vibration excitation system has been developed to excite the rotor blades of an axial compressor, in the specified nodal diameter mode and at the specified frequency, by injecting additional compressed air into the compressor flow path. The system was fitted to the Rofanco compressor test bench at the University of Stellenbosch in South Africa. A two-way staggered fluid–structure interaction (FSI) model was constructed that was capable of simulating the vibrations of the rotor blades excited by the vibration excitation system. The results of the FSI simulations were verified using available experimental data. It was concluded that the FSI model is able to recreate the vibrations of the rotor blades with sufficient accuracy. The results of the FSI simulations also indicated that the vibration excitation system should be capable of exciting the blades in the selected mode shape and at the selected frequency, provided the excitation frequency is close to the natural frequency of the first bending mode of each rotor blade. [ABSTRACT FROM AUTHOR]

Microprocessor pin fins are arguably one of the most ubiquitous cooling panaceas for a plethora of integrated chip (IC) electronics. The present study is an attempt to numerically analyze the thermal performance of microprocessor pin fins of different geometries for inline and staggered arrangements using finite volume method based solver Ansys Fluent. The effects of various parameters like Reynolds number, inter spacing ratio and the geometry of fins on the heat dissipation rate are explored. Inline and staggered arrangements for cylindrical and conical fins with same effective lengths are considered. Nusselt number for each arrangement with Reynolds number varying from 3423 to 34230 is calculated and considered as the selection criteria for heat transfer application of heat sinks with a constant wattage unit attached to it. Design and boundary conditions corresponding to different fins are taken pertaining to standard practices available through open literature. Results show a significant enhancement in heat transfer for staggered arrangement as compared to inline making it suitable for low Reynolds number micro heat transfer applications. An increment in Nusselt number is observed with increasing Reynolds Number for each of the arrangements and fin geometries. [ABSTRACT FROM AUTHOR]

In the salt trimethoprimium ferrocenecarboxylate [systematic name: 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidin-1-ium ferrocene-1-carboxylate], (C14H19N4O3)[Fe(C5H5)(C6H4O2)], (I), of the antibacterial compound trimethoprim, the carboxylate group interacts with the protonated aminopyrimidine group of trimethoprim via two N-H...O hydrogen bonds, generating a robust R22(8) ring motif (heterosynthon). However, in the cocrystal 4-amino-5-chloro-2,6-dimethylpyrimidine-ferrocene-1-carboxylic acid (1/1), [Fe(C5H5)(C6H5O2)]·C6H8ClN3, (II), the carboxyl-aminopyrimidine interaction [ R22(8) motif] is absent. The carboxyl group interacts with the pyrimidine ring via a single O-H...N hydrogen bond. The pyrimidine rings, however, form base pairs via a pair of N-H...N hydrogen bonds, generating an R22(8) supramolecular homosynthon. In salt (I), the unsubstituted cyclopentadienyl ring is disordered over two positions, with a refined site-occupation ratio of 0.573 (10):0.427 (10). In this study, the two five-membered cyclopentadienyl (Cp) rings of ferrocene are in a staggered conformation, as is evident from the C... Cg... Cg...C pseudo-torsion angles, which are in the range 36.13-37.53° for (I) and 22.58-23.46° for (II). Regarding the Cp ring of the minor component in salt (I), the geometry of the ferrocene ring is in an eclipsed conformation, as is evident from the C... Cg... Cg...C pseudo-torsion angles, which are in the range 79.26-80.94°. Both crystal structures are further stabilized by weak π-π interactions. [ABSTRACT FROM AUTHOR]

This article deals with the multiscale modeling of stress transfer characteristics of nano-reinforced polymer composite reinforced with regularly staggered carbon fibers. The distinctive feature of construction of nano-reinforced composite is such that the microscale carbon fibers are packed in hexagonal array in the carbon nanotube reinforced polymer matrix (CNRP). We considered three different cases of CNRP, in which carbon nanotubes (CNTs) are: (i) aligned along the direction of carbon fiber, (ii) aligned radially to the axis of carbon fiber, and (iii) randomly dispersed. Accordingly, multiscale models were developed. First, molecular dynamics (MD) simulations and then Mori-Tanaka technique were used to estimate the effective elastic properties of CNRP. Second, a micromechanical three-phase shear lag model was developed considering the staggering effect of microscale fibers and the application of radial loads on the cylindrical representative volume element (RVE) of nano-reinforced composite. Our results reveal that the stress transfer characteristics of the nano-reinforced composite are significantly improved by controlling the CNT morphology, particularly, when they are randomly dispersed around the microscale fiber. The results from the developed shear lag model were also validated with the finite element shear lag simulations and found to be in good agreement. [ABSTRACT FROM AUTHOR]

The preliminary findings of a comparative study of heat transfer rate and pressure drop between conventional staggered flow and double cross flow heat exchanger is reported. Excepting for the tube arrangements, the shell and tube dimensions, materials and inlet conditions are retained the same for the two configurations. While in the conventional arrangement, adjacent rows of tubes are normal only to the fluid flow in the shell, in the double cross-flow arrangement, they are normal to both fluid flow direction in the shell as well as to each other. Shell dimensions are 100 cm × 20 cm × 20 cm and tube outside and inside diameters are 1 cm and 0.8 cm. The shell and tube materials are steel and copper. Water and air were considered as tube and shell side fluids respectively, with an overall arrangement of parallel flow. The tube flow Reynolds number was fixed at 2200 and the shell flow Reynolds number was varied from 20 to 120 in the laminar regime and 360 to 600 in the turbulent zone. The study reveals that the proposed configuration gives a maximum increase of about 27 per cent in the heat transfer rate per unit pressure drop over the conventional one. [ABSTRACT FROM AUTHOR]

Unstructured meshes allow easily representing complex geometries and to refine in regions of interest without adding control volumes in unnecessary regions. However, numerical schemes used on unstructured grids have to be properly defined in order to minimise numerical errors. An assessment of a low Mach algorithm for laminar and turbulent flows on unstructured meshes using collocated and staggered formulations is presented. For staggered formulations using cell-centred velocity reconstructions, the standard first-order method is shown to be inaccurate in low Mach flows on unstructured grids. A recently proposed least squares procedure for incompressible flows is extended to the low Mach regime and shown to significantly improve the behaviour of the algorithm. Regarding collocated discretisations, the odd-even pressure decoupling is handled through a kinetic energy conserving flux interpolation scheme. This approach is shown to efficiently handle variable-density flows. Besides, different face interpolations schemes for unstructured meshes are analysed. A kinetic energy-preserving scheme is applied to the momentum equations, namely, the symmetry-preserving scheme. Furthermore, a new approach to define the far-neighbouring nodes of the quadratic upstream interpolation for convective kinematics scheme is presented and analysed. The method is suitable for both structured and unstructured grids, either uniform or not. The proposed algorithm and the spatial schemes are assessed against a function reconstruction, a differentially heated cavity and a turbulent self-igniting diffusion flame. It is shown that the proposed algorithm accurately represents unsteady variable-density flows. Furthermore, the quadratic upstream interpolation for convective kinematics scheme shows close to second-order behaviour on unstructured meshes, and the symmetry-preserving is reliably used in all computations. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This study investigates the pattern of flow past two staggered array cylinders using the spectral element method by varying the distance between the cylinders and the angle of incidence (α) at low Reynolds numbers (Re = 100-800). Six flow patterns are identified as Shear layer reattachment (SLR), Induced separation (IS), Vortex impingement (VI), Synchronized vortex shedding (SVS), Vortex pairing and enveloping (VPE), and Vortex pairing splitting and enveloping (VPSE). These flow patterns can be transformed from one to another by changing the distance between the cylinders, the angle of incidence, or Re. SLR, IS and VI flow patterns appear in regimes with small angles of incidence (i.e., α ≤ 30° ) and hold only a single von Karman vortex shedding in a wake with one shedding frequency. SVS, VPE and VPSE flow patterns appear in regimes with large angles of incidence (i.e., 30° ≤ α ≤ 50° ) and present two synchronized von Karman vortices. Quantitative analyses and physical interpretation are also conducted to determine the generation mechanisms of the said flow patterns. [ABSTRACT FROM AUTHOR]

The aim of the experimental study is to investigate the performance of indirect evaporator cooler in hot and humid regions. A novel approach is implemented in the cooler using clay pipe with different orientation as aligned and staggered position for potential and feasibility study. The clay pipe is the ceramic material where the water filled inside the tube and due to the property of porosity, the water comes outer surface of the tube and contact with the air passing over the tube and air get cooled. A test rig was designed and fabricated to collect experimental data. The clay pipes were arranged in aligned and staggered position. In our study heat transfer was analyzed with various air velocity of 1 m/s to 5 m/s. The air temperature, relative humidity, pressure drop and water evaporation rate were measured and the performance of the evaporative cooler was evaluated. The experimental results were compared with mathematical values. The analysis of the data indicated that cooling effectiveness improve with decrease of air velocity at staggered position. It was shown that staggered position has the higher performance (53%) at 5 m/s air velocity in comparison with aligned position. The experimental of heat and mass transfer coefficients were compared with Colburn heat and mass transfer group. The test results were within the limit of 20% of mathematical values. [ABSTRACT FROM AUTHOR]

Abstrak— Peningkatan performa alat penukar kalor pada sisi eksternal telah banyak diteliti, salah satunya adalah memodifikasi bentuk tube dari silinder sirkular menjadi silinder ellips. Perubahan bentuk geometri dapat meningkatkan perpindahan panas sisi eksternal karena silinder ellips adalah salah satu bentuk dari streamlined body dua dimensi. Titik separasi yang tertunda pada ellips mengakibatkan pada berkurangnya gaya drag yang dimiliki body dibandingkan dengan silinder sirkular. Penelitian dilakukan dengan menganalisis karakteristik aliran fluida pada sisi eksternal elliptical tube bank yang tersusun secara staggered dengan perbandingan ratio sebesar 1:3. Fluida kerja berupa udara berkecepatan konstan sebesar 4 m/s dimodelkan sebagai gas ideal yang mengalir pada sisi eksternal dengan kondisi temperatur sebesar 308 K dan heat flux pada tube sebesar 2000 W/m2. Studi numerik dilakukan secara 2 dimensi dengan kondisi aliran steady dengan menggunakan perangkat lunak Computational Fluid Dynamic CFD. Model turbulensi yang digunakan adalah Renormalization Group (RNG) k-ε. Hasil studi bertujuan untuk mengetahui fenomena aliran dan perpindahan panas pada elliptical tube banks, ditinjau secara kualitatif menggunakan visualisasi kontur temperatur dan kecepatan, serta secara kuantitatif dengan menganalisa grafik kecepatan lokal dan Nusselt number. Dari analisis numerik ini diperoleh hasil variasi PL dan PT akan mempengaruhi nilai koefisien heat transfer, temperatur, dan kecepatan dari setiap model A, B, C, D, E, F, G, H dan I. Peningkatan nilai rata-rata kecepatan lokal kontur yang dihasilkan untuk tube banks dibandingkan dengan model A yang memiliki nilai Vavg = 3.361 m/s. Peningkatan kecepatan model B adalah sebesar 14.38 %, C = 37.67%, D = 5.21%, E = 16.24%, F = 38.78 %, G = 7.75%, H = 19.25% dan model I sebesar 42.61%. Peningkatan nilai rata-rata Nusselt lokal dimana model A memiliki nilai Nuavg = 95.8292. Peningkatan Nusselt model B adalah sebesar 7.29 %, C = 16.03%, E =4.67%, F = 15.35 %, G = 0.44%, H = 4.63% dan model I sebesar 16.91%. Pada model D terjadi penurunan nilai Nusselt lokal senbesar 0.24%. Penurunan tekanan (ΔP) terjadi pada semua model, Model A memiliki ΔP sebesar 12.88 Pa, B = 18.41 Pa, C=36.35 Pa, E= 17.97 Pa, F= 36.18 Pa, G =14.97, H = 19.62 Pa, I = 36.54 Pa. Penurunan ΔP terjadi pada model D yang memiliki ΔP sebesar 12.79 Pa dibandingkan dengan model A. Model I dengan PL = 1 dan PT = 1 memiliki nilai Coefficient heat transfer ,kecepatan lokal dan pressure drop yang paling tinggi dibandingkan model variasi lainnya.

• The SPCF with a combination of staggered structures and fins is proposed. • The enhanced reflection of the SPCF is attributed to the shift of the peak position. • The improved sound insulation performance is attributed to the structural coupling effect. Noise is associated with physical and mental health and well-being. Sound insulation materials allowing ventilation are in demand. A staggered phononic crystal with fins (SPCF), which is a combination of staggered structures and fins, is proposed to improve the sound insulation performance and meanwhile allow ventilation. The maximum peak value (5.2 dB) of the experimentally measured transmission loss of the SPCF is higher than the peak values of the reference samples. The improved sound insulation performance of the SPCF compared with reference samples is attributed to the frequency shift effect and structural coupling effect. The dissipated energy caused by the thermal effect in the SPCF accounts for about 20 %-26 % of the total dissipated energy, suggesting that the thermal effect must be considered to obtain an accurate total dissipated energy. The SPCF sets up a new strategy for the next-generation sound insulation materials allowing ventilation. [ABSTRACT FROM AUTHOR]