bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design of Microfabricated Mechanically Interlocking Metamaterials for Reworkable Heterogeneous Integration
Authors: Garcia Geoffrey A. , Wakumoto Kody , Brown Joseph J. 
Published: September 2021

Abstract
Next-generation interconnects utilizing mechanically interlocking structures enable permanent and reworkable joints between micro-electronic devices. Mechanical metamaterials, specifically dry adhesives, are an active area of research which allows for the joining of objects without traditional fasteners or adhesives, and in the case of chip integration, without solder. This paper focuses on reworkable joints that enable chips to be removed from their substrates to support reusable device prototyping and packaging, creating the possibility for eventual pick-and-place mechanical bonding of chips with no additional bonding steps required. Analytical models are presented and are verified through finite element analysis (FEA) assuming pure elastic behavior. Sliding contact conditions in FEA simplify consideration of several design variations but contribute ∼10% uncertainty relative to experiment, analysis, and point-loaded FEA. Two designs are presented; arrays of flat cantilevers have a bond strength of 6.3 kPa, and nonflat cantilevers have a strength of 29 kPa. Interlocking designs present self-aligning in-plane forces that emerge from translational perturbation from perfect alignment. Stresses exceeding the material yield stress during adhesion operations present a greater concern for repeatable operation of compliant interlocking joints and will require further study quantifying and accommodating plastic deformation. Designs joining a rigid array with a complementary compliant cantilever array preserve the condition of reworkability for the surface presenting the rigid array. Eventual realization of interconnect technology based on this study will provide a great improvement of functionality and adaptability in heterogeneous integration and microdevice packaging.
Wake Flow Measurements Behind Rotating Smooth Spheres and Baseballs Near Critical Reynolds Numbers
Authors: Rooney David M. , Mortimer Patrick , Tricouros Frank A. , Vaccaro John C. 
Published: September 2021

Abstract
The flow field behind spinning baseballs at two different seam orientations was investigated, and compared with a smooth sphere, to isolate effects of seams on the Magnus effect at Reynolds numbers of 5×104 and 1×105. The rotational speed of the three spheres varied from 0 to 2400 rpm, which are typical of spin rates imparted to a thrown baseball. These spin rates are represented nondimensionally as a relative spin rate relating the surface tangential velocity to the freestream velocity, and varied between 0 and 0.94. Mean velocity profiles, streamline patterns, and power spectral density of the velocity signals were taken using hot-wire anemometry and/or stereoscopic particle image velocimetry in the wake region. The sphere wake orientation changed over a range of relative spin rates, indicating an inverse Magnus effect. Vortex shedding at a Strouhal number of 0.25 was present on the sphere at low relative spin rates. However, the seams on the baseball prevented any consequential change in wake orientation and, at most spin rates, suppressed the shedding frequency exhibited by the sphere. Instead, frequencies corresponding to the seam rotation rates were observed in the wake flow. It was concluded that the so-called inverse Magnus effect recorded by previous investigators at specific combinations of Reynolds number and relative spin rate on a sphere exists for a smooth sphere or an axisymmetrically dimpled sphere but not for a baseball near critical Reynolds numbers, where the wake flow pattern is strongly influenced by the raised seams.
A Predictive Model for Galling Phenomenon and Its Applicability for Deep Drawing Processes
Authors: Karupannasamy D. K. , Kailas S. V. , Shankar S. , Sasikumar K. S. K. 
Published: September 2021

Abstract
Galling is a recurring phenomenon in deep drawing processes which requires frequent maintenance of tools to improve the product surface quality. Adhesive transfer of softer material on the hard tool surface results in sharp features which causes surface roughening of the tools and deterioration of deep drawn products. In this article, an adhesive wear model based on a deterministic approach is developed to predict the galling behavior in a deep drawing process. The model uses the surface topography, material properties and contact conditions to predict the surface roughening of tool surfaces under perfectly plastic conditions. The adhesive transfer of material is considered by the growth of the asperities based on its geometry for the increase in height and radial direction by preserving the original shape and volume consistency. The results of the multi-asperity models show the growth of the transfer layer and its effects due to load, sliding cycle, sliding distance, and affinity of the materials. The results show the influence of the above-said parameters and its applicability for deep drawing process conditions. The simulated results show an 85% level of confidence in comparison with the experiments from literature for the prediction of the surface evolution due to the galling mechanism.
Stiffness Compensation Through Matching Buckling Loads in a Compliant Four-Bar Mechanism
Authors: Numić A. , Blad T.W.A. , van Keulen F. 
Published: September 2021

Abstract
In this paper, a novel alternative method of stiffness compensation in buckled mechanisms is investigated. This method involves the use of critical load matching, i.e., matching the first two buckling loads of a mechanism. An analytical simply supported five-bar linkage model consisting of three rigid links, a prismatic slider joint, and four torsion springs in the revolute joints is proposed for the analysis of this method. It is found that the first two buckling loads are exactly equal when the two grounded springs are three times stiffer than the two ungrounded springs. The force–deflection characteristic of this linkage architecture showed statically balanced behavior in both symmetric and asymmetric actuation. Using modal analysis, it was shown that the sum of the decomposed strain energy per buckling mode is constant throughout the motion range for this architecture. An equivalent lumped-compliant mechanism is designed; finite element and experimental analysis showed near-zero actuation forces, verifying that critical load matching may be used to achieve significant stiffness compensation in buckled mechanisms.
Pool Boiling Heat Transfer Enhancement Using Perforated Twisted Tape Fins
Authors: Joshi Parimesh , Patil Anil Kumar , Kumar Manoj 
Published: September 2021

Abstract
The application of twisted tape fins (TTFs) showed a considerable enhancement in pool boiling heat flux. The present study experimentally investigates the effect of solid and perforated TTFs on pool boiling of water by varying the twist ratio (y) and perforation index (PI) from 3 to 4.3 and 5 to 10, respectively. An arrangement of five TTFs with a twist ratio of 3 showed 18.6% enhancement as compared to the plain surface where an arrangement of five perforated TTFs having a PI of 7 and twist ratio of 3 showed a maximum enhancement of 28.7%.
Multivariate Design and Analysis of Aircraft Heat Exchanger Under Multiple Working Conditions Within Flight Envelope
Authors: Liu Qihang , Xu Guoqiang , Wen Jie , Fu Yanchen , Zhuang Laihe , Dong Bensi 
Published: September 2021

Abstract
This paper presents a multi-condition design method for the aircraft heat exchanger (HEX), marking with lightweight, compactness, and wide range of working conditions. The quasi-traversal genetic algorithm (QT-GA) method is introduced to obtain the optimal values of five structural parameters including the height, the tube diameter, the tube pitch, and the tube rows. The QT-GA method solves the deficiency of the conventional GA in the convergence, and gives a clear correlation between design variables and outputs. Pressure drops, heat transfer, and the weight of the HEX are combined in a single objective function of GA in the HEX design, thus the optimal structure of the HEX suitable for all the working conditions can be directly obtained. After optimization, the weight of the HEX is reduced to 2.250 kg, more than 20% lower than a common weight of around 3 kg. Based on the optimal structure, the off-design performance of the HEX is further analyzed. Results show that the extreme working conditions for the heat transfer and the pressure drops are not consistent. It proves the advance of the multi-condition design method over the traditional single-condition design method. In general, the proposed QT-GA design method is an efficient way to solve the multi-condition problems related to the aircraft HEX or other energy systems.
A Comparative Study of Multiple Regression and Machine Learning Techniques for Prediction of Nanofluid Heat Transfer
Authors: Kocak Eyup , Aylı Ece , Turkoglu Hasmet 
Published: September 2021

Abstract
The aim of this article is to introduce and discuss prediction power of the multiple regression technique, artificial neural network (ANN), and adaptive neuro-fuzzy interface system (ANFIS) methods for predicting the forced convection heat transfer characteristics of a turbulent nanofluid flow in a pipe. Water and Al2O3 mixture is used as the nanofluid. Utilizing fluent software, numerical computations were performed with volume fraction ranging between 0.3% and 5%, particle diameter ranging between 20 and 140 nm, and Reynolds number ranging between 7000 and 21,000. Based on the computationally obtained results, a correlation is developed for the Nusselt number using the multiple regression method. Also, based on the computational fluid dynamics results, different ANN architectures with different number of neurons in the hidden layers and several training algorithms (Levenberg–Marquardt, Bayesian regularization, scaled conjugate gradient) are tested to find the best ANN architecture. In addition, ANFIS is also used to predict the Nusselt number. In the ANFIS, number of clusters, exponential factor, and membership function (MF) type are optimized. The results obtained from multiple regression correlation, ANN, and ANFIS were compared. According to the obtained results, ANFIS is a powerful tool with a R2 of 0.9987 for predictions.
Research on Heat Transfer Characteristics and Typical Parameters Sensitivity Analysis of the Deep Borehole Heat Exchanger Combined With the Geothermal Wells
Authors: Ma Jiuchen , Zhang QiuLi , Yi Feiyu , Jiang Qian , Xie Yacheng , Wang Yahui 
Published: September 2021

Abstract
Based on abundant hydrothermal geothermal resources at the depth of 1000–2000 m formation in the basin of the BoHai Bay, the deep borehole heat exchanger (DBHE) combined with the geothermal wells is proposed. According to the modified thermal resistance and capacity model (MTRCM), the heat transfer models inside and outside borehole are established. The transient analytical solutions which are the vertical temperature profiles in the inlet (outlet) pipe and the grout of the DBHE and the corresponding dimensionless form are obtained by deducing and solving the heat transfer models inside the borehole. The mathematical model and the analytical solutions are validated by the experimental data and existing studied data. This paper utilizes respectively the Matlab2012 and the Feflow7.1 to solve the heat transfer models inside and outside the DBHE. The sensitivity analysis is performed to examine the influence of typical parameters on the DBHE heat transfer characteristics, including the quantity of geothermal water exploitation, the well distance between the pumping well and the DBHE, the DBHE inlet temperature, the DBHE depth, and the flowrate of circulating water. Under the action of geothermal wells, the heat transfer mechanism is changed in the thermal reservoir, and the DBHE heat transfer capacity can effectively enhance while the quantity of geothermal water exploitation increases and the well distance decreases. However, with the change of the quantity of geothermal water exploitation, the growth rate of the DBHE heat transfer capacity reduces and the sensitivity of the change of the typical parameters on the DBHE heat transfer performance reduces.
Performance and Economic Analysis of Bubble Column Humidification and Thermoelectric Cooler Dehumidification Water Desalination System
Authors: Patel Vivek , Patel Rajesh , Kumar Sumit 
Published: September 2021

Abstract
Although water is one of the key elements on the globe and accessible in a large amount, nearly one-half of the people of the globe are suffering from a shortage of freshwater that is increasing at a frightening rate, most exclusively in growing nations where commercial water shortages prevail. So, in the regions with ample saline water and solar radiation where freshwater is usually limited, the humidification-dehumidification (H-DH) desalination systems have demonstrated inspiring outcomes. The experimental, theoretical, and economical analysis of the bubble column (BC) humidifier, thermoelectric cooler (TEC) based dehumidifier H-DH system has been presented in this work. The effect of various operational parameters on H-DH systems like Ta, Tw, H, do, and ya has been studied. The daily experimental and theoretical productivity obtained during the analysis of the H-DH system was in the span of 7–13 L/day and 9.1–12.4 L/day, respectively, for dissimilar functional variables while the greatest experimental and theoretical productivity was reported 12.97 L/day and 12.4 L/day, respectively, for do = 2 mm, ya = 0.016 kg/s, Tw = 60 °C, Ta = 27 °C, and H = 7 cm. Also, the experimental results present a fine confirmation with the results of the proposed mathematical model. From the economic analysis, it is found that the yearly price per liter and the payback period of the H-DH system are Rs. 5.1/L and 2.4 years, respectively, which is a very promising value.
Heat Transfer Coefficient Distribution of W and Broken W Turbulators at High Reynolds Numbers
Authors: Ghazi-Hesami Sam , Wise Dylan , Taylor Keith , Robert Étienne , Ireland Peter 
Published: September 2021

Abstract
An experimental and numerical study of the convective heat transfer enhancement provided by two rib families (W and Broken W) is presented, covering Reynolds numbers (Re) between 300,000 and 900,000 in a straight channel with a rectangular cross section (AR = 1.29). These high Reynolds numbers were selected for the current study since most data in the available literature typically pertain to investigations at lower Reynolds numbers. The objective of this study is to assess the local heat transfer coefficient (HTC) enhancement (compared with a smooth channel) and the overall thermal performance, taking into account the effect of increased roughness on the friction factor, of a group of W-shaped turbulators over a wide range of Reynolds numbers. Furthermore, the effects of increasing the rib spacing on the thermal performance of the Broken W configuration are presented and discussed. The numerical results are compared against heat transfer measurements obtained using the transient liquid crystal (TLC) method. The research shows that for the Broken W turbulators, increasing the Reynolds number is associated with an overall decrease of the thermal performance while the thermal performance of the W configuration is relatively insensitive to Reynolds number. Nevertheless, the Broken W configuration delivers higher thermal performance and heat transfer compared with the W configuration for the range of Re investigated. The Broken W configuration with a pitch spacing of 10 times the rib height was shown to provide the optimal thermal performance in the configurations investigated here.
Heat Transfer and Pressure Drop of an Angled Discrete Turbulator at Elevated Reynolds Numbers Up to 900,000
Authors: Ghazi-Hesami Sam , Wise Dylan , Taylor Keith , Ireland Peter , Robert Étienne 
Published: September 2021

Abstract
Turbulators are a promising avenue to enhance heat transfer in a wide variety of applications. An experimental and numerical investigation of heat transfer and pressure drop of a broken V (chevron) turbulator is presented at Reynolds numbers ranging from approximately 300,000 to 900,000 in a rectangular channel with an aspect ratio (width/height) of 1.29. The rib height is 3% of the channel hydraulic diameter, while the rib spacing to rib height ratio is fixed at 10. Heat transfer measurements are performed on the flat surface between ribs using transient liquid crystal (LC) thermography. The experimental results reveal a significant increase of the heat transfer and friction factor of the ribbed surface compared with a smooth channel. Both parameters increase with Reynolds number, with a heat transfer enhancement ratio of up to 2.15 (relative to a smooth channel) and a friction factor ratio of up to 6.32 over the investigated Reynolds number range. Complementary computational fluid dynamics (CFD) Reynolds-averaged Navier–Stokes (RANS) simulations are performed with the κ-ω shear-stress transport (SST) turbulence model in ansys fluent® 17.1, and the numerical estimates are compared against the experimental data. The results reveal that the discrepancy between the experimentally measured area-averaged Nusselt number and the numerical estimates increases from approximately 3% to 13% with increasing Reynolds number from 339,000 to 917,000. The numerical estimates indicate turbulators enhance heat transfer by interrupting the boundary layer as well as increasing near surface turbulent kinetic energy (TKE) and mixing.
Impact of Swirling Entropy Waves on a High Pressure Turbine
Authors: Notaristefano Andrea , Gaetani Paolo 
Published: September 2021

AbstractThe harsh environment exiting modern gas turbine combustion chamber is characterized by vorticity and temperature perturbations, the latter commonly referred as entropy waves. The interaction of these unsteadiness with the first turbine stage causes non-negligible effects on the aerodynamic performance, blade cooling, and noise production. The first of these drawbacks is addressed in this paper by means of an experimental campaign: entropy waves and swirl profile are injected upstream of an axial turbine stage through a novel combustor simulator. Two injection positions and different inlet conditions are considered. Steady and unsteady experimental measurements are carried out through the stage to address the combustor-turbine interaction characterizing the injected disturbance, the nozzle, and rotor outlet aerothermal field. The experimental outcomes show a severe reduction of the temperature perturbation already at stator outlet. The generated swirl profile influences significantly the aerodynamic, as it interacts with the stator and rotor secondary flows and wakes. Furthermore, the clocking position changes the region most affected by the disturbance, showing a potential modifying the injection position to minimize the entropy wave and swirl profile impact on the stage. Finally, this work shows that in order to proficiently study entropy waves, the unsteady aerodynamic flow field stator downstream has to be addressed.
Study on the Vertical Ultrasonic Vibration-Assisted Nanomachining Process on Single-Crystal Silicon
Authors: Wang Jiqiang , Geng Yanquan , Li Zihan , Yan Yongda , Luo Xichun , Fan Pengfei 
Published: September 2021

Abstract
Subsurface damage that is caused by mechanical machining is a major impediment to the widespread use of hard–brittle materials. Ultrasonic vibration-assisted macro- or micromachining could facilitate shallow subsurface damage compared with conventional machining. However, the subsurface damage that was induced by ultrasonic vibration-assisted nanomachining on hard–brittle silicon crystal has not yet been thoroughly investigated. In this study, we used a tip-based ultrasonic vibration-assisted nanoscratch approach to machine nanochannels on single-crystal silicon, to investigate the subsurface damage mechanism of the hard–brittle material during ductile machining. The material removal state, morphology, and dimensions of the nanochannel, and the effect of subsurface damage on the scratch outcomes were studied. The materials were expelled in rubbing, plowing, and cutting mode in sequence with an increasing applied normal load, and the silicon was significantly harder than the pristine material after plastic deformation. Transmission electron microscope analysis of the subsurface demonstrated that ultrasonic vibration-assisted nanoscratching led to larger subsurface damage compared with static scratching. The transmission electron microscopy results agreed with the Raman spectroscopy and molecular dynamic simulation. Our findings are important for instructing ultrasonic vibration-assisted machining of hard–brittle materials at the nanoscale level.
Reflecting on lived experience: Suicide prevention and the importance of social work in mental health
Authors: Ali Behiye , Staniforth Barbara , Adamson Carole 
Published: September 2021

INTRODUCTION: National suicide prevention strategies and action plans have, historically, been written without input from consumers/current users of mental health services. People who could arguably be seen as experts in this area are rarely asked for their knowledge regarding the efficacy of suicide prevention and intervention efforts. The aims of this study were to gain further insight into the effectiveness of suicide prevention intervention in Aotearoa New Zealand by asking service users “What works?” and to promote lived experience as a valid form of evidence. This article focuses on the importance of a holistic model of health and wellbeing and highlights the role played by social workers, both currently and in the future, regarding suicide prevention and intervention efforts.METHODS: Twenty semi-structured interviews were conducted with individuals with lived experience of suicidal ideation and/or attempt.FINDINGS: Using thematic analysis, a variety of interventions were identified which participants found effective, including exercise, addressing physical health needs, practising mindfulness, use of medications and spirituality. These interventions, and others, are presented as themes within a framework of people, body, mind and spirit.CONCLUSIONS: It is important to view health holistically, and social workers can make an important contribution towards wellbeing through the provision of psychosocial interventions. Also, it is crucial to involve individuals with lived experience within research that informs policy and practice, and within collaborative treatment decisions.