bluuebunny/crossref_metadata_2025 huggingface dataset:
Genomic characterization of mating type loci and mating type distribution in two apparently asexual plantation tree pathogens
Authors: Aylward J. , Havenga M. , Dreyer L. L. , Roets F. , Wingfield B. D. , Wingfield M. J.
Published: September 2019

The Eucalyptus stem canker pathogens Teratosphaeria gauchensis and T. zuluensis (Capnodiales, Teratosphaeriaceae) are found in many tropical regions of the world where their hosts are cultivated for plantation forestry. Population genetic analyses have suggested that some populations undergo recombination, even though their sexual states have never been observed. Against this background, the aim of this study was to characterize the mating type (MAT) locus of these species and thus to better understand the basis of their diversity. Known Mycosphaerellaceae MAT genes were used to identify and investigate the MAT locus in the T. gauchensis and T. zuluensis genomes. Both species were found to be heterothallic and primers were designed to amplify the opposite MAT idiomorphs as well as conserved regions within the MAT1‐1‐1 and MAT1‐2‐1 genes. Each Teratosphaeria MAT idiomorph was defined by either the MAT1‐1‐1 or the MAT1‐2‐1 gene, and an idiomorph‐specific hypothetical protein (MAT1‐1‐10 and MAT1‐2‐12). Populations of T. zuluensis from Asia and southern Africa were dominated by a single mating type, whereas the proportions of the different idiomorphs for T. gauchensis in South America and southern Africa were similar. There was no physical evidence of sexual reproduction for either species and it is argued that although recombination may be possible, it is unlikely to form an important part of their life cycles in diseased Eucalyptus plantations. Instead, continuous human‐mediated multiple introductions of these species have probably resulted in the current genetic structure of their populations, which holds risk for future disease outbreaks and interspecific hybridization.
Riemann‐Hilbert problem and matrix discrete Painlevé II systems
Authors: Cassatella‐Contra Giovanni A. , Mañas Manuel
Published: September 2019

Matrix Szegő biorthogonal polynomials for quasi‐definite matrices of Hölder continuous weights are studied. A Riemann‐Hilbert problem is uniquely solved in terms of the matrix Szegő polynomials and its Cauchy transforms. The Riemann‐Hilbert problem is given as an appropriate framework for the discussion of the Szegő matrix and the associated Szegő recursion relations for the matrix orthogonal polynomials and its Cauchy transforms. Pearson‐type differential systems characterizing the matrix of weights are studied. These are linear systems of ordinary differential equations that are required to have trivial monodromy. Linear ordinary differential equations for the matrix Szegő polynomials and its Cauchy transforms are derived. It is shown how these Pearson systems lead to nonlinear difference equations for the Verblunsky matrices and two examples, of Fuchsian and non‐Fuchsian type, are considered. For both cases, a new matrix version of the discrete Painlevé II equation for the Verblunsky matrices is found. Reductions of these matrix discrete Painlevé II systems presenting locality are discussed.
#FamiliesBelongTogether: Facts and Fictions of Race and Family in U.S. Immigration Policy
Authors: Kibria Nazli
Published: September 2019

Family reunification is widely seen as a relatively stable feature of the contemporary U.S. immigration regime protected by the nation’s liberal democratic institutions and humanitarian values. Drawing on critical scholarship that situates immigration policies in racial nation‐building projects, this article explores the development of U.S. family‐based admission policies from 1965 to the early 2000s. I bring attention to the role of racial family logics in the changing character and meaning of these policies. Racial family logics reflect the emergent and contested ways in which families are both idealized and institutionally organized in relation to the state, the economy, and other social institutions to support racial projects. A normative conception of “the family” as a white, heterosexual, male wage earner, nuclear household unit informed the 1965 U.S. Immigration and Nationality Act and its emphasis on family‐based admissions. However, by the 1990s, the landscape of immigration, race, and family in the United States had shifted quite dramatically. The family‐based admissions system was now associated with immigrants from Asia and Latin America rather than Europe. The “browning” of the system was accompanied by its incorporation into racialized projects of state discipline, surveillance, and control over those deemed “undeserving” in relation to neoliberal values of self‐reliant and self‐regulating families.
Household Support and Social Integration in the Year After Prison
Authors: Sirois Catherine
Published: September 2019

The conventional household is typically conceived as a fixed residence where married adults pool incomes and raise their children. In poor communities, however, households are often residentially unstable, fluid in composition, and economically insecure. Men and women who leave prison face extreme disadvantage, and their households are likely to shape social integration after incarceration. Drawing on qualitative and quantitative data from the Boston Reentry Study, this article describes the complex living situations of men and women newly released from prison and proposes a multifaceted concept of household support. Regression analysis with an index measuring household support shows that living in a stable well‐resourced household just after prison release is associated with reduced risks of a new criminal charge, social isolation, and unemployment six to twelve months later. More than just a social unit for sampling and enumeration, the analysis suggests the household is an explanatory concept that can account for the social integration of poor, minority populations often detached from formal sources of economic and social support.
Vascular ultrasonographic findings in canine patients with clinically diagnosed phlebitis
Authors: Lodzinska Joanna , Leigh Hannah , Parys Magdalena , Liuti Tiziana
Published: September 2019

Peripheral vein phlebitis (inflammation) is a relatively frequent complication in dogs, however, published information on the ultrasonographic characteristics is currently lacking. This prospective, observational study describes the ultrasound (US) characteristics of normal canine cephalic veins, and veins with clinical phlebitis. Correlations among US findings and between US findings versus time that the intravenous catheter was in place were investigated. Safety of the US procedure was evaluated. Fifty patients were prospectively recruited for the study and 18 met the final inclusion criteria. Each patient underwent daily US examinations and was assessed for multiple criteria (vascular wall appearance, compressibility, spontaneity of flow, color fill, and presence/absence of filling defects, flow contour, direction, non‐pulsatility). Characteristics of normal canine cephalic veins were as follows: smooth and thin wall, complete compressibility, no flow disturbances, no filling defects, smooth flow contours, and unidirectional, non‐pulsatile flow with no turbulence. Characteristics of cephalic veins with clinical phlebitis were as follows: wall thickening (83%), decreased compressibility (55%), filling defects consistent with intraluminal thrombus (55%), vessel wall hyperechogenicity (44%), and abnormal color Doppler flow (39%). Significant correlations were found between Doppler filling defects and compressibility, Doppler filling defects and presumed thrombosis, and compressibility and presumed thrombosis (P= .001,P= .001,P= .000, respectively). No correlation was found between the US findings and time the intravenous catheter was in place. Findings indicated that duplex and compressibility US are feasible and safe methods for characterizing and monitoring cephalic veins in dogs with clinical phlebitis.
Influence of hairy vetch seed germination and maturation on weediness in subsequent crops
Authors: Pittman K B , Barney J N , Cahoon C W , Flessner M L
Published: September 2019

Hairy vetch is a widely adopted cover crop in the United States. However, hairy vetch can become weedy in subsequent crops as seeds germinate after the cover crop growing season, which is largely attributed to seed dormancy. We conducted two field experiments to determine seed germination, viability and seed production phenology of two common hairy vetch cultivars in Blacksburg and Blackstone, Virginia, US. ‘Groff’ and ‘Purple Bounty’ seed were sown in October 2015 and May 2016 and germination was tracked until June 2017. Subsequently, ungerminated seeds were tested for viability. Both cultivars had <2% germination after the initial germination period, and <1% of seed recovered was still viable at the end of the experiments. We also conducted experiments to determine when these cultivars produce viable seed. Hairy vetch seeds were counted and tested for germination in the spring. Both cultivars produced seed beginning in late‐May, but most seed were not viable until mid‐June in Virginia. Our results indicate that seed dormancy is not the primary cause of hairy vetch weediness in subsequent crops as nearly all germination, 99% of the total germinated seed, occurred during the cover crop growing season. Also, if complete termination occurs before mid‐June in Virginia, it is unlikely viable seed will be added to the seed bank. To better utilise this cover crop species, cultivar selection and proper termination are important to prevent weediness.
Effect of the Inlet Geometry on the Flow and Heat Transfer Characteristics of Three-Dimensional Wall Jets
Authors: Godi Sangamesh C. , Pattamatta Arvind , Balaji C.
Published: September 2019

In this work, fluid flow and heat transfer characteristics of three-dimensional (3D) wall jets exiting from a circular and square opening are presented based on experimental investigations. Two hydraulic diameters, namely, 2.5 and 7.5 mm and a Reynolds number range of 5000–20,000 have been considered. Mean velocity and turbulence intensity distribution in the walljet are quantified using a hot wire anemometry. Measurements are done both along the streamwise and spanwise directions. Transient infrared thermography is used for mapping the temperatures over the surface, and the heat transfer coefficients are estimated using a semi-infinite approximation methodology. Results show that, for circular jets, the effect of the jet diameter on the local and the spanwise-averaged Nusselt number is most pronounced near the jet exit. Further, it is also observed that circular jets have an edge over square jets. A correlation with a high correlation coefficient of 0.95 has been developed for spanwise average Nusselt number as a function of the Reynolds number and the dimensionless streamwise distance.
Design and Evaluation of a Dexterous and Modular Hand-Held Surgical Robot for Minimally Invasive Surgery
Authors: Yang Yingkan , Kong Kang , Li Jianmin , Wang Shuxin , Li Jinhua
Published: September 2019

Current surgical instruments with fewer degrees-of-freedom (DOF) for minimally invasive surgery (MIS) have limited capability to perform complicated and precise procedures, such as suturing and knot-tying. To address such a problem, a modular dexterous hand-held surgical robot with an ergonomic handle and 4DOF interchangeable instruments was developed. The kinematic arrangement of the instrument and that of the handle were designed to be the same. A compact roll-yaw-roll transmission was proposed applying cable-driven mechanism. Performance experiments were carried out to evaluate the effectiveness of the overall system. The measured grip forces of the robot ranged from 8.63 N to 19.18 N. The suturing performance score of the robot was significantly higher than that of the conventional instrument (28.8 ± 5.02 versus 17.2 ± 7.43, p = 0.041). The trajectory tracking test and animal experiment verified the accuracy and feasibility of the robot. The proposed robot could improve the surgical performance of MIS, providing various end-effectors and having an intuitive interface in the meantime.
Performance Evaluation of Optically Sensorized Tendons for Articulate Surgical Instruments
Authors: Karthikeyan Rohith , Sigmund Kelly , Park Yong-Lae , Ryu Seok Chang
Published: September 2019

This study proposes an optically sensorized force-sensing tendon for minimally invasive surgical instruments. The tendon is composed of a high strength, polarization maintaining (PM) optical fiber with Bragg sensors (FBGs) that negate the cross-sensitivity of conventional FBGs. The PM-FBG fiber is locally reinforced with high stiffness Kevlar that enhances its load carrying capacity while enabling higher curvatures in tendon routing. The composite tendon has a mean diameter of ∼268 μm which preserves the form-factor of instruments within this scope. Importantly, the tendons can improve the functionality of such tools by enabling local force and tissue-resistance estimation. This paper explores the performance of these sensorized tendons in terms of strength, stability, response under dynamic load, friction, and sensitivity as a force measuring tool within an 18 Ga articulate Nitinol (NiTi) cannula (a proxy for potential applications). Results reaffirm the potential of a bi-modal sensing and actuation component within instruments for robotic surgery.
Study of Interaction Patterns Between Evolving Interfaces Due to Boiling Around Different Arrangements of Heated Cylinders
Authors: Darshan M. B. , Kumar Ravi , Das Arup Kumar
Published: September 2019

An effort has been made to numerically study the interactions between the vapor films generating from multiple heated cylinders placed in a saturated water pool with a view to understand the influence of neighboring interface on growth of vapor films. Lagrangian smoothed particle hydrodynamics (SPH) has been used for domain discretization and interface reconstruction. Unconstrained growth of vapor film around a cylinder is simulated first and the nature of vapor dynamics has been taken as a base case for the study of interaction patterns. Vapor growth has been understood through temporal phase contours, azimuthal thickness variation, and trajectory of the centroid of the vapor mass. It has been shown that the presence of cylinder in vertical neighborhood results in suppression of vapor film generating from the bottom cylinder, whereas, the vapor films generating from two cylinders placed in horizontal neighborhood experience a horizontal shift. Studies have also been made to observe multidirectional interactions of vapor films with heated cylinders placed in an inline array, vertically staggered and horizontally staggered arrangements. It has been found that the highest deviation from unconstrained growth occurs in case of the center cylinder in a horizontally staggered arrangement as compared to others. Mutual interaction coefficient and indices are proposed to judge the best possible arrangement in case of a requirement for placement of stacked cylinders.
A Novel Equivalence Approximate Model for Second Law Based Optimization of Three-Fluid Cross-Flow Plate-Fin Heat Exchanger Using Genetic Algorithm
Authors: Aasi Harpreet Kaur , Mishra Manish
Published: September 2019

Number of entropy generation is a significant performance evaluation factor for heat exchanger as it results in trade-off between heat transfer and pressure drop. Optimization of the three-fluid heat exchanger (3−FHX) for minimum number of entropy generation unit requires ε−NTU relation which is unavailable for three-fluid cross-flow heat exchanger due to various complexities involved. A new approximate methodology for the optimization is presented by proving the equivalence of 3−FHX with a coupled two-fluid heat exchanger (2−FHX) followed by using ε−NTU relationship for 2−FHX. The experimental and numerical validation of the equivalence model is presented. Three-fluid cross-flow compact heat exchanger with offset strip fins is optimized for minimum number of entropy generation units using genetic algorithm (GA). Optimum design variables including heat distribution factor are determined for different cross-flow arrangements of 3−FHX with heat duty and pressure drop as constraint for both even and uneven fin dimensions case in all the passages. The present complex model including large number of continuous design variables can be handled well by GA. Validation of the results is carried out by using graphical techniques and very good agreement is observed. Additionally, sensitivity of the heat exchanger dimension has also been checked on the number of entropy generation along with the pressure drop in all the three fluids.
Demonstration and Experimental Validation of Plastic-Encased Resonant Ultrasonic Piezoelectric Actuator for Magnetic Resonance Imaging-Guided Surgical Robots
Authors: Carvalho Paulo A. W. G. , Nycz Christopher J. , Gandomi Katie Y. , Fischer Gregory S.
Published: September 2019

Intra-operative medical imaging based on magnetic resonance imaging (MRI) coupled with robotic manipulation of surgical instruments enables precise feedback-driven procedures. Electrically powered nonferromagnetic motors based on piezoelectric elements have shown to be well suited for MRI robots. However, even avoiding ferrous materials, the high metal content on commercially available motors still cause distortions to the magnetic fields. We construct semicustom piezoelectric actuators wherein the quantity of conductive material is minimized and demonstrate that the distortion issues can be partly addressed through substituting several of these components for plastic equivalents, while maintaining motor functionality. Distortion was measured by assessing the root-mean-squared (RMS) change in position of 49 centroid points in a 12.5 mm square grid of a gelatin-filled phantom. The metal motor caused a distortion of up to 4.91 mm versus 0.55 mm for the plastic motor. An additional signal-to-noise-ratio (SNR) drop between motor off and motor spinning of approximately 20% was not statistically different for metal versus plastic (p = 0.36).
Experimental Rotordynamic Force Coefficients for a Diffusion Bonded Compliant Hybrid Journal Gas Bearing Utilizing Fluid-Filled Hermetic Dampers
Authors: Gary Keith , Ertas Bugra
Published: September 2019

Dynamic force coefficients are presented from experimental results of a radial gas bearing with hermetically sealed squeeze film dampers (HSFDs) in the bearing support. HSFDs are a relatively new technology aimed to increase damping levels in gas bearings while sustaining an oil-free bearing sump. Past HSFD designs proved bulky and contained many components making it difficult to employ in size-limited environments such as jet engines, while the diffusion bonded bearing discussed in this paper provides a compact integral design. Details of the design are found in a companion paper by Ertas (Ertas, B. H., 2019, “Compliant Hybrid Gas Bearing Using Integral Hermetically-Sealed Squeeze Film Dampers,” ASME Paper No. GT2018-76312). Test results for a 3 in. (76.2 mm) diameter bearing using a test rig providing static loads up to 80 lbs (356 N), controlled-dynamic orbital motion, and speeds up to 27 krpm are shown. Results include frequency- and speed-dependent direct and cross-coupled rotordynamic force coefficients. Dynamic testing showed little dependence on rotor speed or static load and exhibited frequency dependency at lower excitation frequencies. Cross-coupled terms are generally an order of magnitude lower than direct terms. Results show the direct stiffness coefficients increasing with frequency, while direct damping decays radically with frequency. Comparison of the overall gas bearing coefficients with the companion paper (Ertas, B. H., 2019, “Compliant Hybrid Gas Bearing Using Integral Hermetically-Sealed Squeeze Film Dampers,” ASME Paper No. GT2018-76312), showing bearing support coefficients, reveals a drastic reduction in damping when engaging the gas film. The results also indicate that the bearing can withstand vibration levels representative of a large rotor system critical speed at lower excitation frequencies.
Compliant Hybrid Gas Bearing Using Integral Hermetically Sealed Squeeze Film Dampers
Authors: Ertas Bugra
Published: September 2019

This paper focuses on an integral gas-film lubricated bearing concept developed to enable the oil-free operation of super-critical carbon dioxide (sCO2) turbomachinery. The externally pressurized tilting pad bearing concept possesses a flexible bearing support with an integral hermetically sealed squeeze film damper. Unlike the past concepts using modular hermetic squeeze film dampers presented, the bearing design in this work utilizes advanced manufacturing methods to yield an integral single piece design in efforts to reduce space envelope, cost, and improve overall design reliability. The paper advances a detailed description of the bearing design and identification of bearing support force coefficients. Nonrotating benchtop tests show the influence of vibration amplitude, frequency, and damper cavity pressurization on force coefficients for two different viscosity fluids. Results indicate an increase in stiffness and a decrease in damping when increasing the frequency of excitation. Damper cavity pressurization was shown to eliminate squeeze film cavitation for the vibration amplitudes and frequency range in the study. Additionally, the paper advances a transient fluid–structure interaction (FSI) analysis aimed at gaining insight on the interaction of flexible elements bounding a hermetic fluid volume experiencing sinusoidal vibratory motion. The analysis considers an idealized damper model with and without a vibration transmission post while varying diaphragm modulus of elasticity for three excitation frequencies. Computational results were able to capture the increase in stiffness and the decrease in damping and show that the flexibility of the bounding elements influence the damper cavity volume change and phase ultimately affecting dynamic cavity pressures and force coefficients.
Applying Machine Learning Methods Toward Classification Based on Small Datasets: Application to Shoulder Labral Tears
Authors: Clymer Daniel R. , Long Jason , Latona Carmen , Akhavan Sam , LeDuc Philip , Cagan Jonathan
Published: September 2019

Machine learning is a powerful tool that can be applied to pattern search and mathematical optimization for making predictions on new data with unknown labels. In the field of medical imaging, one challenge with applying machine learning techniques is the limited size and relative expense of obtaining labeled data. For example, in glenoid labral tears, current imaging diagnosis is best achieved by imaging through magnetic resonance (MR) arthrography, a method of injecting contrast-enhancing material into the joint that can potentially cause discomfort to the patient, and adds expense compared to a standard magnetic resonance image (MRI). This work proposes limiting the use of MR arthrography through a medical diagnostic approach, based on convolutional neural networks (CNNs) and transfer learning from a separate medical imaging dataset to improve the efficiency and effectiveness. The results indicate an effective method applied to a small dataset of unenhanced shoulder MRI in order to diagnose labral tear severity while potentially significantly reducing cost and reducing unnecessary invasive imaging techniques. The proposed method ultimately can reduce physician workload while ensuring that the least number of patients as possible need to be subjected to an additional invasive contrast-enhanced imaging procedure.
A New Strategy for Laser Trepanning of Tapered Microholes
Authors: Song Jiacheng , Shen Hong , Yao Zhenqiang
Published: September 2019

Most researches on laser drilling focus on the reduction of the hole taper to improve the hole quality. However, tapered microholes are very useful in some industry applications. In this paper, a new method of laser drilling tapered microholes by tilting and rotating the workpiece is put forward and corresponding experimental installation is setup. The relationship between workpiece coordinate system and laser processing coordinate system is established to eliminate the hyperbolic error induced by this method. The microhole is machined through rotating the workpiece and the machining speed is achieved with laser beam circle motion by the galvanometer system. The tapered microholes are obtained on ceramic and high temperature alloy materials using the present method and the taper accuracy can be improved through the compensation strategy. High reliability and repeatability ensure that this method can be applied in industry application.
Three-Dimensional Transient Heat Conduction Equation Solution for Accurate Determination of Heat Transfer Coefficient
Authors: Ahmed Shoaib , Singh Prashant , Ekkad Srinath V.
Published: September 2019

Accurate quantification of local heat transfer coefficient (HTC) is imperative for design and development of heat exchangers for high heat flux dissipation applications. Liquid crystal and infrared thermography (IRT) are typically employed to measure detailed surface temperatures, where local HTC values are calculated by employing suitable conduction models, e.g., one-dimensional (1D) semi-infinite conduction model on a material with the low thermal conductivity and low thermal diffusivity. Often times, this assumption of 1D heat diffusion and ignoring its associated lateral conduction effects leads to significant errors in HTC determination. Prior studies have identified this problem and quantified the associated errors in HTC determination for some representative cooling concepts, by accounting for lateral heat diffusion. In this paper, we have presented a procedure for solution of three-dimensional (3D) transient conduction equation using alternating direction implicit (ADI) method and an error minimization routine to find accurate HTCs at relatively lower computational cost. Representative cases of a single jet and an array jet impingement under maximum crossflow condition have been considered here, for IRT and liquid crystal thermography, respectively. Results indicate that the globally averaged HTC obtained using the 3D model was consistently higher than the conventional 1D model by 7–14%, with deviation levels reaching as high as 20% near the stagnation region. Proposed methodology was computationally efficient and is recommended for studies aimed toward local HTC determination.
Gas Turbine Health State Prognostics by Means of Bayesian Hierarchical Models
Authors: Losi Enzo , Venturini Mauro , Manservigi Lucrezia
Published: September 2019

The prediction of time evolution of gas turbine (GT) performance is an emerging requirement of modern prognostics and health management (PHM), aimed at improving system reliability and availability, while reducing life cycle costs. In this work, a data-driven Bayesian hierarchical model (BHM) is employed to perform a probabilistic prediction of GT future behavior, thanks to its capability to deal with fleet data from multiple units. First, the theoretical background of the predictive methodology is outlined to highlight the inference mechanism and data processing for estimating BHM-predicted outputs. Then, the BHM approach is applied to both simulated and field data representative of GT degradation to assess its prediction reliability and grasp some rules of thumb for minimizing BHM prediction error. For the considered field data, the average values of the prediction errors are found to be lower than 1.0% or 1.7% for single- or multi-step prediction, respectively.
Aerodynamic Design Optimization of an Axial Flow Compressor Stator Using Parameterized Free-Form Deformation
Authors: Adjei Richard Amankwa , Wang WeiZhe , Liu YingZheng
Published: September 2019

This paper describes an aerodynamic design optimization of a highly loaded compressor stator blade using parameterized free-form deformation (FFD). The optimization methodology presented utilizes a B-spline-based FFD control volume to map the blade from the object space to the parametric space via transformation operations in order to perturb the blade surface. Coupled with a multi-objective genetic algorithm (MOGA) and a Gaussian process-based response surface method (RSM), a fully automated iterative loop was used to run the optimization on a fitted correlation function. A weighted average reduction of 6.1% and 36.9% in total pressure loss and exit whirl angle was achieved, showing a better compromise of objective functions with smoother blade shape than other results obtained in the open literature. Data mining of the Pareto set of optimums revealed four groups of data interactions of which some design variables were found to have skewed scatter relationship with objective functions and can be redefined for further improvement of performance. Analysis of the flow field showed that the thinning of the blade at midspan and reduction in camber distribution were responsible for the elimination of the focal-type separation vortex by redirecting the secondary flow in an axially forward direction toward the midspan and near the hub endwall downstream. Furthermore, the reduction in exit whirl angle especially at the shroud was due to the mild bow shape which generated radial forces on the flow field thereby reducing the flow diffusion rate at the suction surface corner. This effect substantially delayed or eliminated the formation of corner separation at design and off-design operating conditions. Parameterized FFD was found to have superior benefits of smooth surface generation with low number of design variables while maintaining a good compromise between objective functions when coupled with a genetic algorithm.
Inexpensive Computations Using Computational Fluid Dynamics Combined With Asymptotics Applied to Laminar Mixed Convection in a Vertical Channel
Authors: Nakate Prasheel , Kotresha Banjara , Gnanasekaran N.
Published: September 2019

In this work, a solution technique is proposed by synergistically combining asymptotics and computational fluid dynamics to ascertain a problem of laminar mixed convection heat transfer in a vertical channel. First, numerical simulation is carried out on a vertical channel that consists of an aluminum heater plate assembly at the center of the channel. The numerical model is treated as a conjugate heat transfer problem, and the concept of perturbation and blending is incorporated wherein the limiting solution of natural and forced convection is obtained in terms of average Nusselt number. These correlations are then blended to find a unified composite correlation that work very well for extreme limits of mixed convection. The Richardson number is chosen as an independent variable in the present analysis; as a result, the Nusselt number correlation is cogent for the mixed convection region. Upon performing the numerical simulations, the results of the mixed convection are then compared with experimental results available in the literature for the purpose of validation of the numerical solution. The results of the present work emphasize that, with minimum computational fluid dynamics (CFD) solutions, one can obtain a reasonably good composite correlation for the Nusselt number for mixed convection and also a substantial reduction of computations is possible ensuing an asymptotically flawless solution.
Effect of Geometrical Parameters on the Thermal Performance of Ammonia-Based Trapezoidal-Shaped Axial Grooved Heat Pipe
Authors: Desai Akshaykumar N. , Singh V. K. , Patel Rajesh N.
Published: September 2019

Liquid–vapor interfacial shear stresses, contact angle, and thin-film resistance are incorporated in the present numerical model of the axial grooved heat pipe (AGHP). Experiments are performed to validate the numerical model, which predicts maximum heat transportation capacity (Qmax) within 2.5% error. Further, a parametric study is performed using maximum heat transportation capacity (Qmax) and total thermal resistance (Rtotal) as an objective function and geometrical parameters of groove (i.e., height of grooves (hg), number of grooves (N), and groove inclination angle (2υ)) as variables. From the numerical results, it is observed that number of grooves (N) and groove inclination angle (2υ) are inversely proportional to Rtotal as desired. Therefore, an increase in N and 2υ results into reduction in Rtotal. However, an increment in hg increases Rtotal due to liquid layer resistance into the grooves. Study is aimed to determine such a combination of variable which can maximize Qmax and minimize Rtotal. For ammonia based AGHP of 10.5 mm ID, 12.7 mm OD, and 1 m length, the best combination is determined as hg = 1.3 mm, N = 28 and 2υ = 76 deg, which gives Qmax and Rtotal as 109 W and 0.093 K/W, respectively.
Natural Convection Heat and Mass Transfer in the Vertical Cylindrical Porous Channel Under the Effects of Time-Periodic Boundary Condition
Authors: Mohammed Hayder I. , Giddings Donald
Published: September 2019

Heat and mass transfer are investigated numerically with steady-state laminar natural convection through a vertical cylindrical enclosure filled with a liquid-saturated porous medium. The vertical wall is under a constant magnetic field and various durations of periodic heating boundary condition; the top and bottom surfaces are kept at a constant cold temperature. Continuity, momentum, and energy equations are transformed to dimensionless equations. The finite difference approach with the line successive over-relaxation (LSOR) method is used to obtain the computational results. This study covers the heat transfer, the temperature distribution, and the velocity field in the domain under the variation of different parameters. The code used is validated by modifying it to analyze the Nusselt number in the existing experimental literature of Izadpanah et al. (1998, “Experimental and Theoretical Studies of Convective Heat Transfer in a Cylindrical Porous Medium,” Int. J. Heat Fluid Flow, 19(6), pp. 629–635). This work shows that Nusselt number decreases (with varying gradient) as the aspect ratio increases, and that it increases as the Rayleigh number increases. The centerline temperature has a proportional relationship with the heating amplitude and the heating period (as the system receives more heat) and is inversely proportional with Rayleigh number. Increasing the Rayleigh number causes increased convective velocity, which affects the position of the hot region, and causes a decrease in the temperature field. Increasing the aspect ratio results in a warm stream at the center of the cylinder, and when the time period of the heating increases, the circulation becomes faster and the intensity of the temperature contour layers decreases. In this work, a correlation for Nu as a function of the mentioned parameters is developed.
Thermal-Mechanical Fracture Analysis Considering Heat Flux Singularity
Authors: Hu Xiaofei , Ding Xing , Zhao Yanguang , Yao Weian
Published: September 2019

Precise modeling of thermoelastic cracks remains challenging due to the fact that both heat flux and stress fields have singularity issue. In the previous studies, the first author proposed different types of symplectic analytical singular element (SASE) for thermal conduction and stress analysis of cracks. It has been demonstrated that these crack-tip elements of which the interior fields are defined by analytical solutions are highly accurate and efficient. However, the thermal mechanical coupling problem of crack cannot be treated with the existing SASEs. The main difficulty is that the analytical solution of the crack problem considering arbitrary temperature distribution is not available. Approximate solution may lead to significant numerical instabilities. Moreover, the construction of a crack-tip singular element for both thermal conduction and stress analysis is complicated and requires more efforts. In this study, the governing symplectic dual equation of thermoelastic crack is restudied. The analytical solution considering arbitrary temperature distribution is obtained in close form which, to the best of the authors' knowledge, has not been found before. Then, the finite element formulation of a new SASE for thermal-mechanical fracture analysis is derived analytically through a variational approach. A two-step analysis procedure is proposed to calculate the mixed mode thermal stress intensity factors (TSIFs)) and the analysis can be done on a fixed finite element mesh. Mesh refinement around the crack tip is unnecessary, and the mixed-mode TSIFs can be solved accurately without any postprocessing.
Experimental Investigation of Heat Transfer Correlation for Direct Contact Membrane Distillation
Authors: Ve Quoc Linh , Rahaoui Kawtar , Bawahab Mohammed , Faqeha Hosam , Date Abhijit , Akbarzadeh Aliakbar , Do Minh Cuong , Nguyen Quang Lich
Published: September 2019

This paper presents an experimental investigation of heat transfer in direct contact membrane distillation (DCMD) flow channels with and without the spacer. In this experiment, the usual hydrophobic membrane of DCMD is replaced by a copper plate to eliminate mass transfer. The study shows the most appropriate heat transfer correlations for empty channel cases with different channel heights and flow rates. For the case with the spacer in the flow channels, two spacer materials are investigated: nonwoven plastic and woven stainless steel. The paper presents the most appropriate heat transfer correlation for both these spacer materials. Further, the paper presents finding with two more spacer materials, woven fiberglass and aluminum spacer. It is found that the most appropriate heat transfer correlation for these materials is in the turbulent flow regime although the experimentally estimated Reynolds number suggests laminar flow is presented.
A Graphical Design Approach for Two-Input Single-Output Systems Exploiting Plant/Controller Alignment: Design and Application
Authors: Weir Nathan A. , Alleyne Andrew G.
Published: September 2019

Due to the unique structure of two-input single-output (TISO) feedback systems, several closed-loop properties can be characterized using the concepts of plant and controller “directions” and “alignment.” Poor plant/controller alignment indicates significant limitations in terms of closed-loop performance. In general, it is desirable to design a controller that is well aligned with the plant in order to minimize the size of the closed-loop sensitivity functions and closed-loop interactions. Although the concept of alignment can be a useful analysis tool for a given plant/controller pair, it is not obvious how a controller should be designed to achieve good alignment. We present a new controller design approach, based on the PQ method (Schroeck et al., 2001, “On Compensator Design for Linear Time invariant Dual-Input Single-Output Systems,” IEEE/ASME Trans. Mechatronics, 6(1), pp. 50–57), which explicitly incorporates knowledge of alignment into the design process. This is accomplished by providing graphical information about the alignment angle on the Bode plot of the PQ frequency response. We show the utility of this approach through a design example.
Lower Limb Assistive Device Design Optimization Using Musculoskeletal Modeling:A Review
Authors: Grabke Emerson Paul , Masani Kei , Andrysek Jan
Published: September 2019

Many individuals with lower limb amputations or neuromuscular impairments face mobility challenges attributable to suboptimal assistive device design. Forward dynamic modeling and simulation of human walking using conventional biomechanical gait models offer an alternative to intuition-based assistive device design, providing insight into the biomechanics underlying pathological gait. Musculoskeletal models enable better understanding of prosthesis and/or exoskeleton contributions to the human musculoskeletal system, and device and user contributions to both body support and propulsion during gait. This paper reviews current literature that have used forward dynamic simulation of clinical population musculoskeletal models to perform assistive device design optimization using optimal control, optimal tracking, computed muscle control (CMC) and reflex-based control. Musculoskeletal model complexity and assumptions inhibit forward dynamic musculoskeletal modeling in its current state, hindering computational assistive device design optimization. Future recommendations include validating musculoskeletal models and resultant assistive device designs, developing less computationally expensive forward dynamic musculoskeletal modeling methods, and developing more efficient patient-specific musculoskeletal model generation methods to enable personalized assistive device optimization.
A Probabilistic Uncertainty Estimation Method for Turbulence Parameters Measured by Hot-Wire Anemometry in Short-Duration Wind Tunnels
Authors: Boufidi Elissavet , Lavagnoli Sergio , Fontaneto Fabrizio
Published: September 2019

A robust and complete uncertainty estimation method is developed to quantify the uncertainty of turbulence quantities measured by hot-wire anemometry (HWA) at the inlet of a short-duration turbine test rig. The uncertainty is categorized into two macro-uncertainty sources: the measurement-related uncertainty (the uncertainty of each instantaneous velocity sample) and the uncertainty stemming from the statistical treatment of the time series. The former is addressed by the implementation of a Monte Carlo (MC) method. The latter, which is directly related to the duration of the acquired signal, is estimated using the moving block bootstrap (MBB) method, a nonparametric resampling algorithm suitable for correlated time series. This methodology allows computing the confidence intervals of the spanwise distributions of mean velocity, turbulence intensity, length scales, and other statistical moments at the inlet of the turbine test section.
Phytoseiid mites of the subgenus Typhlodromus (Anthoseius) De Leon (Acari: Mesostigmata: Phytoseiidae) in Taiwan

Authors: Liao Jhih-Rong , Ho Chyi-Chen , Ko Chiun-Cheng
Published: September 2019

Predatory mites belonging to family Phytoseiidae (Acari: Mesostigmata) have received great attention. The subgenus Typhlodromus (Anthoseius) De Leon is one of the largest and complicated group in the family Phytoseiidae. There are 11 species of Typhlodromus (Anthoseius) reported in Taiwan so far and eight of them described by Y.H. Tseng. In addition, all specimens including types are lost after his retirement. The undetailed descriptions and the simple illustrations caused some difficulties in proper identifications of Taiwanese species. In this study, six species previously described from Taiwan that follows T. (A.) changi, T. (A.) gracilentus, T. (A.) lanyuensis, and T. (A.) neocrassus, T. (A.) obesus, T. (A.) tridentiger, are re-discovered. In addition, three species, T. (A.) bambusae, T. (A.) chinensis, and T. (A.) serrulatus are reported for the first time for Taiwanese fauna. We also provided the first description of male T. (A.) bambusae. Detailed descriptions of all species and a revised key to the Taiwanese species of the subgenus Typhlodromus (Anthoseius) are also included.
Hypocalcemic cardiomyopathy: a rare presenting manifestation of hypoparathyroidism
Authors: Saini Neharika , Mishra Sanat , Banerjee Saurav , Rajput Rajesh
Published: September 2019

Hypoparathyroidism patients present with features of hypocalcemia like carpopedal spasm, numbness and paresthesias but hypocalcemic cardiomyopathy leading to congestive heart failure (CHF) is a rare presentation. We present here a case of 55-year-old Asian man who was a known case of dilated cardiomyopathy for 6 months, presented with the chief complaints of shortness of breath on exertion and decreased urine output. On general physical examination, features suggestive of CHF were seen. Chvostek and Trousseau’s sign was positive. The patient had a history of cataract surgery of both eyes 15 years ago. Further investigations revealed hypocalcemia. Echo showed severe global hypokinesia of left ventricle with left ventricle ejection fraction 15%. This CHF was refractory to conventional treatment, though, with calcium supplementation, the patient improved symptomatically. On follow-up after 3 months, an improvement was seen in the echocardiographic parameters with ejection fraction improving to 25%.
Unusual case of Juvenile Tay-Sachs disease
Authors: Cheema Huma A , Waheed Nadia , Saeed Anjum
Published: September 2019

Tay-Sachs disease (TSD) is a type 1 gangliosidosis (GM2) and caused by hexosaminidase A deficiency resulting in abnormal sphingolipid metabolism and deposition of precursors in different organs. It is a progressive neurodegenerative disorder transmitted in an autosomal-recessive manner. There is an accumulation of GM2 in neurocytes and retinal ganglions which result in progressive loss of neurological function and formation of the cherry-red spot which is the hallmark of TSD. We report the first case of juvenile TSD from Pakistan in a child with death of an older sibling without the diagnosis.
Diagnosis of hypothenar hammer syndrome in a patient with acute ulnar artery occlusion
Authors: St-Pierre Frederique , Shepherd Roger F , Bartlett Matthew Asher
Published: September 2019

A 56-year-old truck driver with a history of tobacco use presented with acute onset digital ischaemia in the ulnar distribution of his dominant hand, associated with severe pain. Occupational exposures included extensive manual labour and prolonged vibratory stimuli. Workup with Doppler and angiography confirmed the diagnosis of hypothenar hammer syndrome (HHS). After the failure of medical management, he underwent ulnar artery thrombectomy with reconstruction and arterial bypass grafting. His pain improved significantly postsurgically, and he was able to return to a normal routine. This case illustrates the classic presentation, examination, imaging findings and management options of HHS. HHS should be considered in patients with digital ischaemia and associated occupational exposures. Diagnosing the condition appropriately allows for optimal management, aiming at minimising symptoms and maximising quality of life.
Monocular elevation deficit after scleral perforation repair
Authors: Saluja Gunjan , Bhari Anju
Published: September 2019

Monocular elevation deficit can result from either inferior rectus restriction, superior rectus palsy or from supranuclear causes. We report a case of monocular elevation deficit after scleral perforation repair which was managed by surgery on contra lateral eye. This improved elevation of the affected eye with no diplopia in the postoperative period.
Endoscopic removal of an incidentally discovered intrauterine contraceptive device eroding into the rectum
Authors: Al Sahaf Mahdi Abdulrasoul , Bseiso Bahaa Farouk , Al-Momen Sami Abdulmohsin , Meshikhes Abdul-Wahed Nasir
Published: September 2019

Intrauterine contraceptive device (IUCD) is a common birth control method. It is safe but can be associated with serious complications including migration into the peritoneal cavity and penetration into other intra-abdominal and pelvic viscera; most commonly the rectosigmoid colon. Different retrieval methods including endoscopy, laparoscopy or open abdominal surgery have been described. We report the case of 38-year-old woman who became pregnant shortly after insertion of the IUCD 6 years prior to presentation. She delivered vaginally and ‘expulsion’ of the device was assumed. Some 4 years later, she had another IUCD inserted and remained asymptomatic till she recently presented with iron-deficiency anaemia. As part of the investigation, diagnostic colonoscopy was performed. Surprisingly, the old IUCD was found penetrating into the midrectum. Uneventful endoscopic removal was performed and she remained well at 3-month follow-up. Migrating IUCD remains asymptomatic and may be discovered accidentally during routine investigation for some other symptoms.