bluuebunny/crossref_metadata_2025 huggingface dataset:
In Situ Joint Stiffness Increases During Skeletal Growth but Decreases Following Partial and Complete Anterior Cruciate Ligament Injury
Authors: Cone Stephanie G. , Piedrahita Jorge A. , Spang Jeffrey T. , Fisher Matthew B.
Published: September 2019

Partial and complete anterior cruciate ligament (ACL) injuries occur in both pediatric and adult populations and can result in loss of joint stability and function. The sigmoidal shape of knee joint function (load-translation curve) under applied loads includes a low-load region (described by slack length) followed by a high-load region (described by stiffness). However, the impact of age and injury on these parameters is not fully understood. The current objective was to measure the effects of age and injury on the shape of joint function in a porcine model. In response to an applied anterior–posterior tibial load, in situ slack did not change (p > 0.05), despite sevenfold increases in joint size with increasing age. Joint stiffness increased from an average of 10 N/mm in early youth to 47 N/mm in late adolescence (p < 0.05). In situ ACL stiffness increased similarly, and changes in in situ joint stiffness and ACL stiffness were highly correlated across ages. With complete ACL injury, in situ slack length increased by twofold to fourfold and in situ stiffness decreased threefold to fourfold across ages (p < 0.05). Partial ACL injury resulted in less dramatic, but statistically significant, increases in joint slack and significant decreases in in situ joint stiffness in the adolescent age groups (p < 0.05). This work furthers our understanding of the interaction between joint biomechanics and ACL function throughout growth and the impact of ACL injury in the skeletally immature joint.
Multiple Impacts and Multiple-Compression Process in the Dynamics of Granular Chains
Authors: Feng Yajie , Kang Wenting , Ma Daolin , Liu Caishan
Published: September 2019

In this paper, we study the dynamics of one-dimensional chains composed of elastoplastic beads. Three uniform chains, which were experimentally studied in the existing literature, are taken as benchmark examples for manifesting wave propagation induced by multiple impacts between particles and by multiple-compression process in a single contact point. We perform simulations using an elastoplastic contact model developed recently for the binary contact of a sphere. Numerical results show good agreement with the experimental observations, including the profile and amplitude of the incident and reflected solitary waves, the travel time of the wave propagation, and the high-frequency oscillations residing in the high-amplitude stress wave. Our simulations also show that the multiple-compression process of the contact between particles is responsible for the oscillations residing in the pulse profile.
New Fractional Analytical Study of Three-Dimensional Evolution Equation Equipped With Three Memory Indices
Authors: Yousef Feras , Alquran Marwan , Jaradat Imad , Momani Shaher , Baleanu Dumitru
Published: September 2019

Herein, analytical solutions of three-dimensional (3D) diffusion, telegraph, and Burgers' models that are equipped with three memory indices are derived by using an innovative fractional generalization of the traditional differential transform method (DTM), namely, the threefold-fractional differential transform method (threefold-FDTM). This extends the applicability of DTM to comprise initial value problems in higher fractal spaces. The obtained solutions are expressed in the form of a γ¯-fractional power series which is a fractional adaptation of the classical Taylor series in several variables. Furthermore, the projection of these solutions into the integer space corresponds with the solutions of the classical copies for these models. The results detect that the suggested method is easy to implement, accurate, and very efficient in (non)linear fractional models. Thus, research on this trend is worth tracking.
An Instantaneous Center of Rotation-Based Extended Kalman Filter Approach for the On-Line Estimation of Wheelchair Tire Slip
Authors: Wolkowicz Kelilah L. , Pentzer Jesse L. , Miller Christopher X. , Moore Jason Z. , Brennan Sean N.
Published: September 2019

Wheelchair tire slip is a dangerous scenario that can result from powered wheelchair operation on icy or low-friction surfaces. This research applies instantaneous center of rotation (ICR) estimation to a wheelchair application where ICR values should rarely change. Changes in these estimates are used to understand the occurrence of slip and to predict the motion during that slip. Using inputs of position and orientation obtained through laser odometry, an extended Kalman filter (EKF) algorithm is implemented to estimate the changes in wheelchair ICR location estimates that are indicative of slippage. The algorithm is verified via simulation and experimentation using a robotic wheelchair. It is observed that the convergence of the ICR EKF is heavily dependent on the motion history of the wheelchair. Experiments show that ICR locations do not vary significantly under the slip-free conditions of normal operation with 2-σ standard deviations of 0.076 m, but the ICR locations deviate up to 0.84 m during slippage.
Gesture Tracking and Locating Algorithm Based on Federated Tracking Filter
Authors: Yu Lei , Hou Junyi , Fei Shumin
Published: September 2019

In this paper, a joint gesture tracking method combining particle filter and mean shift algorithm is proposed to improve the accuracy and robustness of the system. During the slow movement of the human hand, the average movement of the particles is first used to cause most of the particles to drift into the gesture area. In the case where the movement of the human hand is faster or there is occlusion, when the mean shift of the particle is performed, if the region of the gesture is not detected, the particle will return to the state before the drift, and then the next frame is processed. The method can directly calculate the position of the gesture based on the particles used for subsequent testing, and can save the tracking time of the algorithm. Through experimental simulation, compared with the Cam-shift algorithm, when the sampling point of the joint tracking algorithm proposed in this paper is 200, the tracking accuracy is improved to 95.2%. Compared with 90.6% of the Cam-shift algorithm, the tracking time is reduced from 83.7 ms to 25.8 ms. Therefore, the proposed algorithm can greatly improve the tracking accuracy and real-time, and can also effectively reduce the impact of complex environments on the tracking effect.
Drilling Control System Using an Equivalent Input Disturbance-Based Control With a Neutral-Type Axial-Torsional Coupled Dynamics Model
Authors: Ke Chong , Song Xingyong
Published: September 2019

This paper proposed an equivalent input disturbance (EID)-based approach to control the vertical down-hole drilling process. To describe a drill string which is typically long with large axial-to-radius ratio, a neutral-type model is used to accurately capture dynamics of this type of slender string structure. The axial-torsional coupling effect due to drill bit/rock interaction is also included in the model. A new controller is then designed based on the coupled neutral model, and the coupling effect is specifically addressed in the design. To address the uncertainty of the bit/rock interaction, the EID method is used. A new Lyapunov–Krasovskii functional is proposed for the control design. To this end, a series of numerical simulation results are presented to demonstrate the effectiveness of the proposed control scheme.
Progress and Perspective of Near-Ultraviolet and Deep-Ultraviolet Light-Emitting Diode Packaging Technologies
Authors: Peng Yang , Liang Renli , Mou Yun , Dai Jiangnan , Chen Mingxiang , Luo Xiaobing
Published: September 2019

Ultraviolet light-emitting diodes (UV-LEDs) have drawn considerable attention in environment, life science, and industry fields, such as the applications of near UV-LEDs in resin curing, illumination, and identification, and deep UV-LEDs in disinfection, medical treatment, and biochemical inspection. However, due to the limitation of packaging technology, UV-LED devices exhibit low light efficiency and poor reliability compared with visible LEDs. The organic encapsulation materials are prone to UV aging, thermal degradation, and nonairtightness, which significantly reduce the performances of UV-LEDs. In order to solve this issue, UV-LED packaging technology has been proposed for UV-LED devices instead of conventional LED packaging. In this review, we investigated in detail the overview and challenges of near-ultraviolet light-emitting diodes (NUV-LED)/deep-ultraviolet light-emitting diodes (DUV-LED) packaging. For the packaging of UV-LEDs, all inorganic encapsulation materials, hermetic packaging structures with low-temperature bonding, reduced reflection losses, UV stable and transparent materials, and effective thermal management are key progresses to enhance the light efficiency and reliability of UV-LEDs. In addition, the summary and perspectives of NUV-LED/DUV-LED packaging were introduced and discussed.
Discrete Greenwood–Williamson Modeling of Rough Surface Contact Accounting for Three-Dimensional Sinusoidal Asperities and Asperity Interaction
Authors: Zhang S. , Song H. , Sandfeld S. , Liu X. , Wei Y. G.
Published: September 2019

The Greenwood–Williamson (GW) model has been one of the commonly used contact models to study rough surface contact problems during the past decades. While this has been a successful model, it still has a number of restrictions: (i) surface asperities are spheres; (ii) the overall deformation must be assumed to be small enough, such that there is no interaction between asperities, i.e., they are independent of each other; and (iii) asperity deformation remains elastic. This renders the GW model unrealistic in many situations. In the present work, we resolve above restrictions in a discrete version of the GW model: instead of spherical asperities, we assumed that the surface consists of three-dimensional sinusoidal asperities which appear more similar to asperities on a rough surface. For single asperity mechanical response, we propose a Hertz-like analytical solution for purely elastic deformation and a semi-analytical solution based on finite element method (FEM) for elastic–plastic deformation. The asperity interaction is accounted for by discretely utilizing a modified Boussinesq solution without consideration of asperity merger. It is seen that the asperity interaction effect is more than just the delay of contact as shown in the statistical model, it also contributes to the loss of linearity between the contact force and the contact area. Our model also shows that: for elastic contact, using spherical asperities results in a larger average contact pressure than using sinusoids; when plasticity is taken into account, using a sphere to represent asperities results in a softer response as compared with using sinusoids. It is also confirmed that sinusoidal asperities are a much better description than spheres, by comparison with fully resolved FEM simulation results for computer-generated rough surfaces.
Efficiency of Worm Gear Drives Under Transient Operating Conditions
Authors: Oehler Manuel , Sauer Bernd , Magyar Balázs
Published: September 2019

In oil-lubricated worm gears, all moving components cause power losses during operation. These losses depend, among other things, on the viscosity of the lubricant used, which in turn is determined by the temperature present in the gearbox. The dependency between the temperature and the power dissipation is mutual, and they influence each other. For the analysis of gearboxes under transient conditions, the relationship among operating conditions, power dissipation, and temperature must be considered. In this paper, a method for the analysis of these interrelationships is presented, which is based on the combination of tribological simulation and thermal networks. With the developed calculation model, the gearbox efficiency and the temperature over time can be estimated for arbitrary load cases. The calculation results are compared with measurements on a real gearbox.
Passive Wingtip Vortex Control by Using Tip-Mounted Half Delta Wings in Ground Effect
Authors: Lu Anan , Lee Tim
Published: September 2019

The ground effect on the wingtip vortex generated by a rectangular semiwing equipped with tip-mounted regular and reverse half delta wings was investigated experimentally. The passive tip vortex control always led to a reduced lift-induced drag as the ground was approached. In close ground proximity, the presence of the corotating ground vortex (GV) added vorticity to the tip vortex while the counter-rotating secondary vortex (SV) negated its vorticity level. The interaction of the GV and SV with the tip vortex and their impact on the lift-induced drag were discussed. Physical mechanisms responsible for the change in the vortex flow properties in ground effect were also provided.
A Percolation Method of Leakage Calculation and Prediction Within the Mechanical Seal Interface
Authors: Yu Qiuping , Sun Jianjun , Ma Chenbo , Zhang Yuyan
Published: September 2019

The size and change of leakage channel within the mechanical seal interface are investigated to calculate and predict the leakage rate of mechanical seal. Based on the percolation theory, the computing method of the leakage channel within the mechanical seal interface is analyzed; the critical size and change of leakage channel and leakage rate are obtained. The results show that during the period of normal wear, the magnification of the leakage channel increases exponentially with load and time, the height of leakage channel follows a polynomial decline with load and decays exponentially with time. According to the load-dependence or time-dependence of magnification and height, the size of the leakage channel and the leakage rate of the mechanical seal could be calculated and predicted, which is helpful for the optimum design and safe operation of the mechanical seal.
Development of Geometrically Accurate Continuum-Based Tire Models for Virtual Testing
Authors: Grossi Emanuele , Desai Chintan J. , Shabana Ahmed A.
Published: September 2019

In this paper, an approach based on the integration of computer-aided design and analysis (I-CAD-A) is used to develop new continuum-based finite element (FE) tire models for the small and large deformation analyses. Based on given tire specifications, the mechanics-based geometry/analysis absolute nodal coordinate formulation (ANCF) is used to define the tire geometry with the same degree of accuracy as B-splines and nonuniform rational B-spline (NURBS), widely used in the computer-aided design (CAD) systems. In the case of large deformations, the ANCF geometry can be used directly as the analysis mesh without the need for conversion or adjustments. In order to define the material parameters that characterize the ANCF tire composite structure, a virtual test rig is developed, and the tire calibration process is performed according to the standards defined by the Society of Automotive Engineers (SAE). In order to develop small-deformation models that can be used in the prediction of the tire frequencies and mode shapes, the ANCF position vector gradients are consistently written in terms of rotation parameters, leading to geometrically accurate floating frame of reference (FFR) finite elements, referred to as ANCF/FFR elements. Using this mechanics-based geometry/analysis approach, new geometrically accurate reduced-order tire models are systematically developed and used to define vibration equations for the prediction of the tire frequencies, which are verified using a commercial FE software. The element stiffness matrix is calculated using the general continuum mechanics approach (GCM), and the effectiveness of the strain split method (SSM) for locking alleviation is tested. The results obtained in this investigation show that the I-CAD-A tire modeling approach can be used to develop geometrically accurate tire models suited for the large-deformation multibody system (MBS) problems as well as for the prediction of the tire frequencies and mode shapes.
Heuristic-Guided Solution Search Through a Two-Tiered Design Grammar
Authors: Puentes Lucas , Cagan Jonathan , McComb Christopher
Published: September 2019

Grammar-based design is typically a gradual process; incremental design changes are performed until a problem statement has been satisfied. While they offer an effective means for searching a design space, standard grammars risk being computationally costly because of the iteration required, and the larger a given grammar the broader the search required. This paper proposes a two-tiered design grammar that enhances the computational design generation with generalized heuristics to provide a way to more efficiently search a design space. Specifically, this two-tiered grammar captures a combination of heuristic-based strategic actions (often observed in human designers) and smaller-scale modifications (common in traditional grammars). Rules in the higher tier are abstract and applicable across multiple design domains. Through associated guiding heuristics, these macrorules are translated down into a sequence of domain-specific, lower-tier microrules. This grammar is evaluated through an implementation within an agent-based simulated annealing team algorithm in which agents iteratively select actions from either the higher tier or the lower tier. This algorithm is used in two applications: truss generation, which is commonly used for testing engineering design methods, and wave energy converter design generation, which is currently a relevant research area in sustainable energy production. Comparisons are made between designs generated using only lower-tier rules and those generated using only higher-tier rules. Further tests demonstrate the efficacy of applying a combination of both lower-tier and higher-tier rules.
Additive Manufacturing of Bi-Continuous Piezocomposites With Triply Periodic Phase Interfaces for Combined Flexibility and Piezoelectricity
Authors: Song Xuan , He Li , Yang Wenhua , Wang Zhuo , Chen Zeyu , Guo Jing , Wang Hong , Chen Lei
Published: September 2019

An additive manufacturing-enabled bi-continuous piezocomposite architecture is presented to achieve mechanical flexibility and piezoelectricity simultaneously in piezoelectric materials. This architecture comprises an active ferroelectric ceramic phase and a passive flexible polymer phase, which are separated by a tailorable phase interface. Triply periodic minimal surfaces were used to define the phase interface, due to their excellent elastic properties and load transfer efficiency. A suspension-enclosing projection-stereolithography process was used to additively manufacture this material. Postprocesses including polymer infiltration, electroding, and poling are introduced. Piezoelectric properties of the piezocomposites are numerically and experimentally studied. The results highlight the role of tailorable triply periodic phase interfaces in promoting mechanical flexibility and piezoelectricity of bi-continuous piezocomposites.
Intensity-Based Registration With Voxel-Based Computer-Aided Manufacturing for Adaptive Machining
Authors: Collins James S. , Tucker Tommy , Kurfess Thomas
Published: September 2019

This paper presents a novel application of intensity-based volume registration to manufacturing using voxel-based computer-aided manufacturing (CAM) models. The introduced techniques are presented in the context of machining irregularly shaped materials by integrating volumetric imaging feedback to computer numerical control (CNC) machine tools. This requires a comparison and alignment to be performed in the software to geometrically “fit” the source design model inside a rendered starting material. The requirements differ from many typical registration applications in that the workpiece will necessarily be larger (i.e., greater in volume) than the desired final computer-aided design (CAD) file. Therefore, models need to be aligned for toolpath generation to workpiece counterparts that have been either volumetrically offset or contain additional material/volume. Intensity-based registrations are unique in that they consider only the voxel values over the entire volume. Although advancements in medical imaging have produced efficient, robust voxel registration algorithms, these techniques have not yet been applied to manufacturing. This research introduces the use of maximization of mutual information (MMI) for voxel-based CAM to drive an alignment registration for systems integrating imaging technology. A simple but novel method, which the authors have named minimization of distance variance (MDV), is also introduced. This minimizes the variance between voxel intensities to demonstrate the design of a similarity metric for a simple case in machining rough castings.
Design and Kinematic Analysis of a Novel Machine Tool With Four Rotational Axes and One Translational Axis
Authors: Gao Song , Chen Jihong , Liu Shusheng , Yuan Xiukun , Hu Pengcheng , Yang Jianzhong
Published: September 2019

Due to their superior machining quality, efficiency, and availability, five-axis machine tools are important for the manufacturing of complicated parts of freeform surfaces. In this study, a new type of the five-axis machine tool was designed that is composed of four rotary axes as well as one translational axis. Given the structure of the proposed machine tool, an inverse kinematics analysis was conducted analytically, and a set of methods was then proposed to address the issues in the kinematic analysis, e.g., the singularity and multi-solution problems. Compared with traditional five-axis machine tools, which are typically composed of three linear axes and two rotary axes, the proposed machine tool exhibited better kinematic performance with machining parts with hub features, such as impellers, which was validated by simulations and real cuttings.
Effect of Progressive Tool Wear on the Evolution of the Dynamic Stability Limits in High-Speed Micromilling of Ti-6Al-4V
Authors: Mittal Rinku , Maheshwari Chinmay , Kulkarni Salil S. , Singh Ramesh
Published: September 2019

Micromilling can fabricate complex features in a wide range of engineering materials with an excellent finish but the limited flexural stiffness of the micro-end mill can result in catastrophic tool failure. This issue can be overcome by using high rotational speeds. Note that the combination of high rotational speeds and low flexural stiffness can induce process instability which is aggravated by the accelerated wear of the micro-tools at high speeds, specifically, for Ti-alloys. The effect of progressive tool wear on the stability has been investigated in micromilling of Ti-6Al-4V. For incorporating tool wear, the cutting force coefficients are modeled as a function of initial and instantaneous cutting edge radius (CER) and feed per tooth. The initial CER of the micro-tool is considered due to the inherent variability in the tool grinding process. A significant increase (85–114%) in the instantaneous CER is observed with an increase in the length of cut. A 2DOF time-domain model based on semi-discretization method has been used to characterize the evolution of stability limits with an increase in the length of cut. The progressive tool wear affects the stability limits along with the initial CER and the feed per tooth. At higher speeds (90,000–110,000 rpm), the effect of progressive tool wear is pronounced and the stability limits reduce by ∼30% in that range.
Effects of Hull Flexibility on the Structural Dynamics of a Tension Leg Platform Floating Wind Turbine
Authors: Silva de Souza Carlos Eduardo , Bachynski Erin E.
Published: September 2019

Dynamic analysis of floating wind turbines often considers the hull as a rigid body. This paper explores the consequences of modeling the pontoons of a tension leg platform (TLP) wind turbine as flexible beams. The analysis is based on numerical simulations of free decays, structural response to wave excitation, and short-term fatigue damage accumulation at tower base and tendons. In addition, the importance of hydroelastic effects due to the pontoons’ vertical deformations is evaluated. Pontoon flexibility changed the platform natural periods and motion amplitude significantly, and the adoption of flexible pontoons reduced the predicted fatigue damage in the tower base and tendons. On the other hand, hydroelasticity had negligible consequences for motion and load responses considered here.
Degree of Freedom and Dynamic Analysis of the Multi-Loop Coupled Passive-Input Overconstrained Deployable Tetrahedral Mechanisms for Truss Antennas
Authors: Xu Yundou , Chen Yang , Liu Wenlan , Ma Xiaofei , Yao Jiantao , Zhao Yongsheng
Published: September 2019

Recently, the truss antennas with deployable tetrahedron unit mechanisms have been successfully applied in orbit, owing to the advantages of large calibers, high accuracy, and large folding ratios. As multiloop coupled mechanisms, deployable tetrahedral mechanisms have multiple different output links, whose supporting limbs connecting output links and the base are mutually coupled. These mechanisms are also called the passive-input overconstrained mechanisms because their passive torsion springs are used as drivers and because the number of the drivers contained is more than the degrees of freedom (DOFs). In this work, a method based on the equivalent concept of first link-removing and then restoring is proposed for the DOF analysis of the multiloop coupled deployable tetrahedral mechanisms. With one coupled chain removed, the equivalent serial chains between the coupled components and the base are established in the remainder of the mechanisms. Then, the coupled chain removed is restored and the equivalent of the multiloop coupled mechanisms is obtained. The Lagrange method is used to establish the dynamic equation of the passive-input overconstrained mechanisms; the influence of the stiffness and number of torsion springs on the unfolding motion is examined.
Design, Construction, and Control of Curves and Surfaces via Deployable Mechanisms
Authors: Ramadoss Vishal , Zlatanov Dimiter , Ding Xilun , Zoppi Matteo , Lyu Shengnan
Published: September 2019

There has been an increasing interest in design and construction of deployable mechanisms (DMs) with multiple degrees of freedom (DOFs). This paper summarizes a family of deployable mechanisms that approximates a series of curves and surfaces using the polygonal approximation technique. These mechanisms are obtained by linking the two- and three-dimensional deployable units, which are constitutive of Sarrus and scissor linkages. Multiple unit mechanisms with varying sizes are assembled and alter their shape within a different family of parameterized curves and surfaces. A systematic methodology for polygonal approximation method is presented. Quadratic, semi-cubic, cubic, quartic and sextic curve boundaries, and quadric surfaces are approximated and controlled. Computer-aided design (CAD) models and kinematic simulations elucidate the mechanism’s ability to approximate a set of curves and surfaces.
Investigation of Tool Errors and Their Influences on Tooth Surface Topography for Face-Hobbed Hypoid Gears
Authors: Liang Chengcheng , Song Chaosheng , Zhu Caichao , Wang Yawen , Liu Siyuan , Sun Ruihua
Published: September 2019

Tool errors are inevitable in an actual gear-manufacturing environment and may directly affect the accuracy of machined tooth surfaces. In this paper, tool errors including spheric radius, pressure angle, rake angle, regrind angle, and cutting side relief angle errors for three-face blade are defined and considered to establish the accurate tooth surface mathematical model for face-hobbed hypoid gears based on the manufacturing process and the meshing theory. The simulation flowchart for tooth surface modeling and tooth surface topography deviation analysis are proposed and performed. Results show that the tooth surface deviation is positive with positive spheric radius and rake angle errors and contrary results can be found for other three tool errors. In addition, the impact of the pressure angle error is the strongest. In addition, the rake angle error has the weakest effect and the influence of spheric radius error on the tooth surface deviation is unsubstantial. For location of tooth surface deviation, the maximum deviation is at the top on the heel and the minimum deviation is at the middle on the toe for spheric radius error. The maximum and minimum deviations are at the top and the middle tooth on the heel for other factors, respectively.
Numerical Simulation of Flow and Thermal Behavior of Radiating Gas Flow in Plane Solar Heaters
Authors: Foruzan Nia Mohammad , Gandjalikhan Nassab Seyyed Abdolreza , Ansari Amir Babak
Published: September 2019

In this paper, the radiating effect of working gas on thermal performance of plane solar heaters is investigated. In the numerical simulation of gas flow, the continuity and momentum equations are solved using the finite volume method (FVM) in which the pressure–velocity coupling is handled by the SIMPLE algorithm. To obtain the temperature distribution, the conservation of energy in the fluid and solid media is solved by the finite difference technique. The distribution of radiating intensity which is needed to calculate the radiative term in the gas energy equation is computed by numerical solution of the radiative transfer equation (RTE) using the discrete ordinate method (DOM). The effect of the variation of different parameters on the predicted thermal efficiency of plane solar heater is investigated by presenting the performance plot. The obtained results show that when the gas medium participates in radiation, the gas temperature at the outlet section increases considerably, especially at high optical thicknesses. Also, the temperature difference between the absorber plate and flowing gas decreases, and more uniform temperature distribution takes place inside the solar heater, which leads to a considerable increase in thermal efficiency. Comparison between the present numerical results and the experimental data published in literature shows good agreement.
Effect of Fuel Injection Pressure and Engine Speed on Performance, Emissions, Combustion, and Particulate Investigations of Gasohols Fuelled Gasoline Direct Injection Engine
Authors: Sharma Nikhil , Agarwal Avinash Kumar
Published: September 2019

Fuel availability, global warming, and energy security are the three main driving forces, which determine suitability and long-term implementation potential of a renewable fuel for internal combustion engines for a variety of applications. Comprehensive engine experiments were conducted in a single-cylinder gasoline direct injection (GDI) engine prototype having a compression ratio of 10.5, for gaining insights into application of mixtures of gasoline and primary alcohols. Performance, emissions, combustion, and particulate characteristics were determined at different engine speeds (1500, 2000, 2500, 3000 rpm), different fuel injection pressures (FIP: 40, 80, 120, 160 bars) and different test fuel blends namely 15% (v/v) butanol, ethanol, and methanol blended with gasoline, respectively (Bu15, E15, and M15) and baseline gasoline at a fixed (optimum) spark timing of 24 deg before top dead center (bTDC). For a majority of operating conditions, gasohols exhibited superior characteristics except minor engine performance penalty. Gasohols therefore emerged as serious candidate as a transitional renewable fuel for utilization in the existing GDI engines, without requirement of any major hardware changes.
Multicriteria Analysis for Retrofitting of Natural Gas Melting and Heating Furnaces for Sustainable Manufacturing and Industry 4.0
Authors: Arnal Álvaro J. , Díaz-Ramírez Maryori , Acevedo Luis , Ferreira Víctor J. , García-Armingol Tatiana , López-Sabirón Ana M. , Ferreira Germán
Published: September 2019

Different retrofitting measures can be implemented at different levels of the industrial furnace, such as refractory layers, energy recovery solutions, new burners and fuel types, and monitoring and control systems. However, there is a high level of uncertainty about the possible implications of integrating new technologies, not only in the furnace but also on the upstream and downstream processes. In this regard, there is a lack of holistic approaches to design the optimal system configurations under a multicriteria perspective, especially when innovative technologies and multi-sectorial processes are involved. The present work proposes a holistic approach to natural gas melting and heating furnaces in energy-intensive industries. A multicriteria analysis, based on criteria and subcriteria, is applied to select the most profitable retrofitting solution using the analytic hierarchy process and stakeholder expertise. The methodology is based on technical indicators, i.e., life cycle assessment, life cycle cost, and thermoeconomic analysis, for evaluating the current state of existing natural gas furnaces. Once the current state is characterized, the methodology determines the potential of efficiency improvement, environmental impact reduction, and cost-savings caused mainly by the implementation of new retrofitting solutions including new refractories, new burner concepts (co-firing), and innovative energy recovery solutions based on phase change materials. Therefore, this methodology can be considered as the first stage that guarantees technical, environmental, and economic feasibility in evaluating the effects of new technologies on the overall system performance.
Time-Space Spectral Method for Rotor–Rotor/Stator–Stator Interactions
Authors: Huang Xiuquan , Wang Ding Xi
Published: September 2019

The paper presents a time-space spectral method for an efficient analysis of rotor–rotor/stator–stator interactions in the framework of the time spectral form harmonic balance method. The method treats time and space harmonics in a coherent way and allows for easy choice of time and passage through the introduction of pseudo-shaft frequency and composite frequency. The proposed method can accommodate passage to passage variation of time-averaged flow field and amplitude of unsteady flow field of a given frequency as needed for rotor–rotor/stator–stator interactions. Minimum change is required to extend an existing harmonic balance flow solver to incorporate the proposed method. The proposed method is the most concise and the simplest one of its kind so far. The first three blade rows of a two-stage fan are used as a test case to demonstrate the validity and effectiveness of the proposed method. Numerical results demonstrate the necessity of including rotor–rotor/stator–stator interaction in an analysis using a frequency-domain method and the capability of the proposed method for such a purpose. It is also concluded from the case study that extra spatial and temporal harmonics are needed to adequately analyze a rotor–rotor/stator–stator interaction.
The Temple Scroll: Reconstructing an ancient manufacturing practice
Authors: Schuetz Roman , Maragh Janille M. , Weaver James C. , Rabin Ira , Masic Admir
Published: September 2019

Analysis of the Temple Scroll reveals another technology used to produce the Dead Sea Scrolls and potential preservation concerns.
Ultrafast optical field–ionized gases—A laboratory platform for studying kinetic plasma instabilities
Authors: Zhang Chaojie , Huang Chen-Kang , Marsh Ken A. , Clayton Chris E. , Mori Warren B. , Joshi Chan
Published: September 2019

Optical field–ionized gases are used to study kinetic instabilities ubiquitous in ionospheric, cosmic, and terrestrial plasmas.
Gasdermin D activity in inflammation and host defense
Authors: Lieberman Judy , Wu Hao , Kagan Jonathan C.
Published: September 2019

This Review summarizes our current understanding of the functions of gasdermin D.
Changing of the guard
Authors: Clark Rachael A.
Published: September 2019

Anti-PD-1 therapy induces clonal expansion of tumor-specific T cells with antigen specificities distinct from the tumor-specific T cells present before therapy.
Sugar Mommy
Authors: Pillai Shiv
Published: September 2019

During pregnancy, mothers generate di-galactosylated IgGs that cross the placenta more readily and provide the fetus and the newborn infant with antibodies optimized for NK cell–mediated antibody-dependent cellular cytotoxicity.
Exposure to Broad-Spectrum Visible Light Causes Major Transcriptomic Changes in
Listeria monocytogenes
EGDe
Authors: Sæbø Pettersen Kristin , Sundaram Arvind Y. M. , Skjerdal Taran , Wasteson Yngvild , Kijewski Anne , Lindbäck Toril , Aspholm Marina
Published: September 2019

Despite major efforts to control
L. monocytogenes
, this pathogen remains a major problem for the food industry, where it poses a continuous risk of food contamination. The ability of
L. monocytogenes
to sense and adapt to different stressors in the environment enables it to persist in many different niches, including food production facilities and in food products. The present study shows that exposure of
L. monocytogenes
to low-intensity broad-spectrum visible light reduces its growth and motility and alters its multicellular behavior. Light exposure also caused genome-wide changes in transcript levels, affecting multiple metabolic pathways, which are likely to influence the bacterial physiology and lifestyle. In practical terms, the data presented in this study suggest that broad-spectrum visible light is an important environmental variable to consider as a strategy to improve food safety by reducing
L. monocytogenes
contamination in food production environments.
Carbon Starvation Induces the Expression of PprB-Regulated Genes in Pseudomonas aeruginosa
Authors: Wang Congcong , Chen Wenhui , Xia Aiguo , Zhang Rongrong , Huang Yajia , Yang Shuai , Ni Lei , Jin Fan
Published: September 2019

Typically, the determination of the external signals that can trigger a regulatory system is crucial to understand the regulatory logic and inward function of that system. The PprA-PprB two-component system was reported to be involved in biofilm formation in
Pseudomonas aeruginosa
, but the signals triggering this system are unknown. In this study, we found that carbon starvation stress (CSS) induces transcription of
pprB
and genes in the PprB regulon through an RpoS-dependent pathway. Increased PprB expression leads to enhanced cell-cell adhesion (CCA) and cell-surface adhesion (CSA) in
P. aeruginosa
. Both CCA and CSA are largely dependent on the Bap secretion system and are moderately dependent on the CupE fimbriae. Our findings suggest that PprB reinforces the structure of biofilms under carbon-limited conditions, and the Bap secretion system and CupE fimbriae are two potential targets for biofilm treatment.
Phenotypic Heterogeneity of the Insect Pathogen Photorhabdus luminescens: Insights into the Fate of Secondary Cells
Authors: Eckstein Simone , Dominelli Nazzareno , Brachmann Andreas , Heermann Ralf
Published: September 2019

The biological function and the fate of
P. luminescens
2° cells were unclear. Here, we performed comparative transcriptomics of
P. luminescens
1° and 2° cultures and found several genes, not only those coding for known phenotypic differences of the two cell forms, that are up- or downregulated in 2° cells compared to levels in 1° cells. Our results suggest that when 1° cells convert to 2° cells, they drastically change their way of life. Thus, 2° cells could easily adapt to an alternative environment such as the rhizosphere and live freely, independent of a host, putatively utilizing plant-derived compounds as nutrient sources. Since 2° cells are not able to reassociate with the nematodes, an alternative lifestyle in the rhizosphere would be conceivable.
Phosphatidylcholine Biosynthesis in Mitis Group Streptococci via Host Metabolite Scavenging
Authors: Joyce Luke R. , Guan Ziqiang , Palmer Kelli L.
Published: September 2019

We lack fundamental information about the composition of the cellular membrane even for the best-studied pathogens of critical significance for human health. The mitis group streptococci are closely linked to humans in health and disease, but their membrane biology is poorly understood. Here, we demonstrate that these streptococci scavenge major human metabolites and use them to synthesize the membrane phospholipid PC. Our work is significant because it identifies a mechanism by which the major human pathogen
S. pneumoniae
and the primary human oral colonizers
S. mitis
and
S. oralis
remodel their membranes in response to host metabolites.
Multiple sulfur isotopes reveal a possible non-crustal source of sulfur for the Bushveld Province, southern Africa
Authors: Magalhães Nivea , Farquhar James , Bybee Grant , Penniston-Dorland Sarah , Rumble Douglas , Kinnaird Judith , McCreesh Matthew
Published: September 2019

The source of sulfur for sulfide mineralization is a major question for the origin of platinum group element deposits such as the Rustenburg Layered Suite (RLS) of the Bushveld Complex and the nearby Waterberg Project (WP; a large palladium-dominant deposit) in southern Africa. Both deposits are mafic-ultramafic intrusions associated with the ca. 2.06 Ga Bushveld magmatism but are hosted in distinct country rocks. This contrast allows a critical assessment of the contribution upper crustal assimilation provides to sulfide mineralization, and refinement of our understanding of sources of mass-independent fractionated sulfur (MIF-S) to these intrusions. The WP has a signature of anomalous sulfur (average Δ33S = 0.113‰ ± 0.016‰, 1 s.d.), similar to the RLS (avgerage Δ33S = 0.137‰ ± 0.025‰, 1 s.d.). There is no evidence for influence of host rock as a source of anomalous sulfur. The lack of a significant variation of Δ33S values within the WP stratigraphy, and the distinct upper continental crust into which the WP magmas would have been emplaced, shows that addition of upper crustal sulfur is not necessary for PGE formation. This suggests that contamination of WP and RLS magmas with a surface-derived component of Archean age occurred at depth, prior to emplacement.
Paleogene global cooling–induced temperature feedback on chemical weathering, as recorded in the northern Tibetan Plateau
Authors: Fang Xiaomin , Galy Albert , Yang Yibo , Zhang Weilin , Ye Chengcheng , Song Chunhui
Published: September 2019

Plate-tectonic processes have long been thought to be the major cause of the Cenozoic global carbon cycle, and global cooling by uplift of the Tibetan Plateau through enhancing silicate weathering and organic carbon burial and/or by weathering of obducted ophiolites during the closure of the Neo-Tethys Ocean. However, the imbalance resulting from accelerated CO2 consumption and a relatively stable CO2 input from volcanic degassing during the Cenozoic should have depleted atmospheric CO2 within a few million years; therefore, a negative feedback mechanism must have stabilized the carbon cycle. Here, we present the first almost-complete Paleogene silicate weathering intensity (SWI) records from continental rocks in the northern Tibetan Plateau showing that silicate weathering in this tectonically inactive area was modulated by global temperature. These findings suggest that Paleogene global cooling was also strongly influenced by a temperature feedback mechanism, which regulated silicate weathering rates and hydrological cycles and maintained a nearly stable carbon cycle. It acted as a negative feedback by decreasing CO2 consumption resulting from the lower SWI and the kinetic limitations in tectonically inactive areas.
The effects of differential compaction on clinothem geometries and shelf-edge trajectories
Authors: Beelen Daan , Jackson Christopher A.-L. , Patruno Stefano , Hodgson David M. , Trabucho Alexandre João P.
Published: September 2019

The geometry of basin-margin strata documents changes in water depth, slope steepness, and sedimentary facies distributions. Their stacking patterns are widely used to define shelf-edge trajectories, which reflect long-term variations in sediment supply and relative sea-level change. Here, we present a new method to reconstruct the geometries and trajectories of clinoform-bearing basin-margin successions. Our sequential decompaction technique explicitly accounts for downdip lithology variations, which are inherent to basin-margin stratigraphy. Our case studies show that preferential compaction of distal, fine-grained foresets and bottomsets results in a vertical extension of basin-margin strata and a basinward rotation of the original shelf-edge trajectory. We discuss the implications these effects have for sea-level reconstructions and for predicting the timing of sediment transfer to the basin floor.
Utility of cardiac imaging in diagnosis of atypical presentation of cardiac fibroma
Authors: Flores Catalina , Lundberg Jaclyn , Richardson Randy R , Prasad Deepa
Published: September 2019

Primary cardiac tumours are relatively rare in the paediatric population, with benign tumours accounting for >90% of cases. Cardiac fibromas are rare primary tumours that typically reside in the ventricles. Symptoms are usually the result of blood outflow obstruction or disruption of the cardiac conduction system. They do not typically regress and usually require surgical intervention. In this case, we report a rare finding of a right atrial fibroma in an 18-month-old female who presented with lethargy and vomiting. Chest X-ray revealed an enlarged cardiac silhouette, and follow-up CT showed a 3.7×3.2×3.7 cm hypodense lesion in the right atrium. Cardiac MRI revealed the diagnosis, which was confirmed on pathology.
Accuracy of magnetic resonance imaging texture analysis in differentiating low-grade from high-grade gliomas: systematic review and meta-analysis
Authors: Wang Qiangping , Lei Deqiang , Yuan Ye , Zhao Hongyang
Published: September 2019

Objectives

Texture analysis (TA) is a method used for quantifying the spatial distributions of intensities in images using scanning software. MRI TA could be applied to grade gliomas. This meta-analysis was performed for assessing the accuracy of MRI TA in differentiating low-grade gliomas from high-grade ones.

Methods

PubMed, Cochrane Library, Science Direct and Embase were searched for identifying suitable studies from their inception to 1 September 2018. The quality of the studies was evaluated on the basis of the Quality Assessment of Diagnostic Accuracy Studies guidelines. We estimated the pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic OR (DOR) using the summary receiver operating characteristic (SROC) for identifying the accuracy of MRI TA in grading gliomas. Fagan nomogram was applied for assessing the clinical utility of TA.

Results

Six studies including 440 patients were included and analysed. The pooled sensitivity, specificity, PLR, NLR and DOR with 95% CIs were 0.93 (95% CI 0.88 to 0.96), 0.86 (95% CI 0.81 to 0.89), 6.4 (95% CI 4.8 to 8.6), 0.08 (95% CI 0.05 to 0.15) and 78 (95% CI 39 to 156), respectively. The SROC curve showed an area under the curve of 0.96 (95% CI 0.93 to 0.97). Deeks test confirmed no significant publication bias in all studies. Fagan nomogram revealed that the post-test probability increased by 43% in patients with positive pre-test.

Conclusions

The findings of this meta-analysis suggested that MRI TA has high accuracy in differentiating low-grade gliomas from high-grade ones. A standardised methodology is warranted to guide the use of this technique for clinical decision-making.