bluuebunny/crossref_metadata_2025 huggingface dataset:
Habitat quality and edge area of fragments determine insect diversity in a heavily used landscape: Implications for forest landscape restoration
Authors: Ramalingam Ravi , Dharma Rajan Priyadarsanan
Published: November 2021

Worldwide, forest fragmentation and degradation have affected the flora and fauna, and are threatening the livelihood of people depending upon forest resources. It is essential to understand the underlying ecological processes to better manage such landscapes. In ecological assessments, insects are useful tools to assess the effects of human interventions such as restoration, as insects are vital for several ecosystem processes. Therefore, we studied the ecological processes that determined the distributions of the epigeic insect communities among the degraded forest fragments of the Attappady Hills (Western Ghats, India), which are being restored. Our objectives were to determine the spatial variations in the epigeic insect communities and their responses to habitat quantity and quality of the forest fragments, along with an assessment of the invasive ants’ responses to fragmentation and degradation, and their effects on the native insect communities. We used pitfall traps in several forest fragments representing varying disturbance levels along an east–west gradient. The diversity of various insect taxonomic groups and functional feeding guilds were higher in smaller fragments than compared to larger fragments due to edge effects. The variations in the distributions of insect communities were explained by the habitat features that were spatially correlated. Invasive ants, Anoplolepis gracilipes, infested the smaller fragments where the vegetation quality had degraded. We conclude that an understanding of the effects of fragmentation and degradation on insect communities is vital to restoration managers as ecological restoration becomes an important strategy to reverse degradation and to revive ecological processes of fragmented forests.

Abstract in Malayalam is available with online material.
Oral supplementation of inorganic pyrophosphate in pseudoxanthoma elasticum
Authors: Kozák Eszter , Fülöp Krisztina , Tőkési Natália , Rao Nidhi , Li Qiaoli , Terry Sharon F. , Uitto Jouni , Zhang Xiaoming , Becker Cyrus , Váradi András , Pomozi Viola
Published: November 2021

Pseudoxanthoma elasticum (PXE; OMIM 264800) is a rare heritable multisystem disorder, characterized by ectopic mineralization affecting elastic fibres in the skin, eyes and the cardiovascular system. Skin findings often lead to early diagnosis of PXE, but currently, no specific treatment exists to counteract the progression of symptoms. PXE belongs to a group of Mendelian calcification disorders linked to pyrophosphate metabolism, which also includes generalized arterial calcification of infancy (GACI) and arterial calcification due to CD73 deficiency (ACDC). Inactivating mutations in ABCC6, ENPP1 and NT5E are the genetic cause of these diseases, respectively, and all of them result in reduced inorganic pyrophosphate (PPi) concentration in the circulation. Although PPi is a strong inhibitor of ectopic calcification, oral supplementation therapy was initially not considered because of its low bioavailability. Our earlier work however demonstrated that orally administered pyrophosphate inhibits ectopic calcification in the animal models of PXE and GACI, and that orally given Na4P2O7 is absorbed in humans. Here, we report that gelatin‐encapsulated Na2H2P2O7 has similar absorption properties in healthy volunteers and people affected by PXE. The sodium‐free K2H2P2O7 form resulted in similar uptake in healthy volunteers and inhibited calcification in Abcc6−/− mice as effectively as its sodium counterpart. Novel pyrophosphate compounds showing higher bioavailability in mice were also identified. Our results provide an important step towards testing oral PPi in clinical trials in PXE, or potentially any condition accompanied by ectopic calcification including diabetes, chronic kidney disease or ageing.
Heat stress effects on the reproductive physiology and yield of wheat
Authors: Ullah Aman , Nadeem Faisal , Nawaz Ahmad , Siddique Kadambot H. M. , Farooq Muhammad
Published: November 2021

Climate change is adversely affecting wheat yields as the associated rising temperatures damage its reproductive physiology. Heat stress affects wheat at various stages of growth, but flowering and reproductive phases are the most sensitive to high temperatures as flower opening usually occurs in cooler environments. Heat stress at meiosis causes ovule and pollen sterility along with anther dehiscence. During pollen development, temperatures >30°C cause pollen abortion. At anthesis, heat stress limits resource translocation to developing grain, resulting in small grain and low yields. During grain development, heat stress shortens the grain‐filling duration and decreases starch and protein accumulation due to reduced activity of grain biosynthesis enzymes and impaired flag leaf assimilatory efficiency and stem reserve mobilization. The development of heat‐tolerant wheat genotypes through screening, selection and breeding using genetic engineering, exogenous application of osmoprotectants and agronomic approaches is a high priority. This review discusses the impact of heat stress on flower development and fertilization, grain development and reproductive failure in wheat and outlines strategies (i.e. breeding and selection, genetic engineering, molecular breeding and management) to improve heat tolerance in wheat.
On Chomsky's notion of explanatory adequacy
Authors: Cipriani Enrico
Published: November 2021

The starting point of this work is the notion of explanatory adequacy. After summarising and analysing the presentation that Chomsky gives of this notion in the first works of generative grammar, I consider the role that such notion has been playing in the construction of the theory of generative grammar and in the foundation of the Universal Grammar research program, focussing, in particular, on the last phase of generative grammar, that is, minimalism.
A global phylogenetic regionalization of vascular plants reveals a deep split between Gondwanan and Laurasian biotas
Authors: Carta Angelino , Peruzzi Lorenzo , Ramírez‐Barahona Santiago
Published: November 2021

Existing global regionalization schemes for plants consider the compositional affinities among biotas, but these have not explicitly considered phylogenetic information. Here, we present for the first time, a phytogeographical delineation of the global vascular flora based on species‐level evolutionary relationships.

We analysed 8737 820 geographical occurrence records for vascular plants together with a time‐calibrated phylogeny including 67 269 species. We constructed a global phylogenetic regionalization by estimating species composition and phylogenetic beta diversity among 200 km × 200 km grid cells across the world.

We identified de novo 16 phytogeographical units that are deeply split into two clusters: Laurasian and Gondwanan. Our regionalization broadly matches previous schemes, but also highlights the separation of the Gondwanan biota into an Holotropical cluster and an Australian–Neozealandic–Patagonian cluster. In contrast, no clear split among Laurasian and Gondwanan biotas was retrieved when omitting phylogenetic information.

The integration of phylogenetic and geographical information provides new insights into the delineation of phytogeographical areas and their historical relationships, enabling the identification of three large, clearly differentiated biotas, here referred to as kingdoms: Holarctic, Holotropical, and Austral. Our results provide further evidence for delineating transition zones and show a clear latitudinal pattern of increasing evolutionary distinctiveness towards the poles.
Good governance: Contemporary issues in political philosophy
Authors: Kirby Nikolas
Published: November 2021

The legislature and the judiciary have been a constant focus of contemporary political philosophy. However, the executive – ‘the government’itself – has been comparatively neglected. Today, this is changing with a well‐spring of new work that bears upon what we might call the ideal of ‘good governance’, that is, how governments (and/or their agents) should exercise their powers. This review paper begins by clarifying the concepts of ‘governance’ and ‘good’ governance (§1). It then highlights five sets of values, working nominally from the most foundational constraints on the exercise of government power to those that should guide the exercise of discretion: legitimacy and rule of law (§2); respect and trustworthiness (§3); efficiency and rationality (§4); public participation and accountability (§5); and the public interest and fiduciary duties (§6).
Computational Micro-Mechanical Model of Composite and Flexible Woven Fabric With Fiber Reorientation
Authors: Tabiei Ala , Ivanov Ivelin
Published: November 2021

This work presents a computational material model of flexible woven fabric for finite element impact analysis and simulation. The model is implemented in the nonlinear dynamic explicit finite element code LSDYNA. The material model derivation utilizes the micro-mechanical approach and the homogenization technique usually used in composite material models. The model accounts for reorientation of the yarns and the fabric architecture. The behavior of the flexible fabric material is achieved by discounting the shear moduli of the material in free state, which allows the simulation of the trellis mechanism before packing the yams. The material model is implemented into the LSDYNA code as a user defined material subroutine. The developed model and its implementation is validated using an experimental ballistic test on Kevlar® woven fabric. The presented validation shows good agreement between the simulation utilizing the present material model and the experiment.
Three-Dimensional Elasticity Solution for the Buckling of Sandwich Columns
Authors: Kardomateas George A.
Published: November 2021

A study of the buckling of a sandwich column, based on the three dimensional theory of elasticity, and a comparison with the simple Euler or transverse shear correction Engesser / Haringx / Timoshenko column buckling formulas, is presented. All three phases of the sandwich structure (two face sheets and the core) are assumed to be orthotropic and the column is in the form of a hollow circular cylinder. The Euler or Engesser / Haringx / Timoshenko loads are based on the equivalent axial modulus. Representative results show the significance of the effect of transverse shear in these sandwich structures.
Effects of Material Failure on Buckling Behaviour of Medium-Thick GFRP Cylindrical Shells for Submarine Applications
Authors: Carvelli Valter , Panzeri Nicola , Poggi Carlo
Published: November 2021

The paper is concerned with the interaction of buckling and material failure in composite cylindrical shells subject to external pressure. A methodology for the numerical prediction of the strength of composite shells is discussed and an application is presented. The results of an experimental and numerical research on a composite shell structure, intended as a model for an under-water vehicle for service in deep-sea environment, are recalled. It is showed how a reasonable prediction of the buckling pressure can be obtained only including the effects of the geometric imperfections. The validated finite element model is then adopted for a parametric study on the influence of the thickness variation on the failure behaviour of cylinders. A well-known failure criteria for composite laminates (Tsai-Wu) is introduced in the model to study the interaction between buckling and material failure in composite cylinders subject to hydrostatic pressure. The values of the pressure obtained with linear buckling, first-ply and progressive failure analysis with or without geometric effects are discussed for a specific composite cylinder.
Light Weight Design in Body-in-White Development Considering Passive Safety Requirements
Authors: Passek Boris
Published: November 2021

Aside from aerodynamics, resistance to rolling, and the engine efficiency itself, mass is the most influencing factor of fuel consumption and therefore vehicle emission.

Over the last years, the automobile industry has generally met the ever-increasing requirements on comfort and passive safety with increases in vehicle mass. However, with the European Community together with Automobile Manufacturers’ Association (ACEA), setting fleet average fuel consumption goals for 2008 to 5.81 petrol/100km (5.251 diesel/100km), this practice has to be not only stopped, but reversed. Very simply, it means that vehicle mass has to decrease while current and new legal requirements on passive safety will continue to have to be met. Additionally, comfort goals have to remain abreast of market demands.

The use of alternative, lightweight materials in the Body-in-White offers the possibility of reducing vehicle mass without influencing the general concept of the car.

The basis for an optimal vehicle structure is set in the initial phase of development. Consideration of implementing alternative materials has to occur at this stage in order to be successful. In order to be cost effective, these feasibility studies are primarily determined by simulation. For this purpose, it is imperative to have dependable models for these alternative materials, which can describe, not only their linear-elastic properties, but also the non-linear behavior and damage.

One common choice for lightweight material which is seeing more and more use in the automobile industry is aluminum which has only one third the density of steel.

This paper discusses the simulating and testing process for structural aluminum components in a BMW vehicle, starting with a general introduction to the problems of simulating aluminum alloys. BMW’s Z8 project is used as example, emphasis being placed on passive safety subjects.
Diagnosis and Diagnostic Rule Extraction Using Fuzzy Neural Network
Authors: Li C. James , Lee Chong-suhk , Wang Sun’an
Published: November 2021

The goal of this study is to develop a reasoning device and a diagnostic rule extraction methodology based on fuzzy neural network. This paper describes a method to obtain a fuzzy neural network classifier from labeled training data sets and algorithms to extracted linguistic diagnostic rules from such a trained fuzzy neural network. Benchmark comparisons were performed using three data sets from three different fields of applications. The proposed methodology was shown to outperform all the existing methods that were compared.
Dynamic Temperature Testing and Modeling for an Automatic Transmission Clutch
Authors: DeMurry Thomas , Wang Yanying
Published: November 2021

The primary objectives of this study are (1) to validate the hardware design and control methodologies for preserving the thermo-mechanical integrity of a launch clutch emulating a torque converter and (2) to develop a simple, control oriented clutch-temperature model that may act as a virtual thermocouple in the processor of an automobile for real-time clutch-temperature predictions. In a dynamometer test cell, a Ford CD4E transaxle is instrumented with a thermocouple-based telemetry system to investigate clutch thermal characteristics during engagements, neutral idle, single and repeated launching, torsional isolation, and hill holding. A nonlinear, SIMULINK™-based model for estimating temperature is developed. The results from the simulations are in good agreement with the experimental data.
Hybrid Operating Strategy and Energy Management for a Hybrid Electric Vehicle
Authors: Bailey Kathleen , Jankovic Miroslava , Phillips Anthony , Blankenship John , Cikanek Susan
Published: November 2021

This paper describes the development of the Low Storage Requirement (LSR) Hybrid Electric Vehicle (HEV) Vehicle System Controller (VSC). It defines the LSR configuration and discusses the advantages of this particular configuration. The main focus of this paper is the hybrid operating strategy for this vehicle and the details of the hybrid operating modes. This hybrid vehicle was developed as a part of the U. S. Department of Energy (DOE) Hybrid Propulsion Systems Development Program that was conducted under a cost-shared subcontract funded equally by Ford and DOE through the Midwest Research Institute which manages and operates DOE’s National Renewable Energy Laboratory in Golden, CO.
Feasibility Assessment and Operating Policy Optimization of Automotive Powertrains With Uncertainties Using Game Theory
Authors: Kolmanovsky Ilya , Siverguina Irina
Published: November 2021

The paper describes a game-theoretic framework and a computational algorithm for feasibility evaluation of automotive powertrains with storage elements in terms of fuel economy and emissions performance. The game-theoretic framework allows to handle various time-dependent uncertainties, including uncertainties in the drive cycle. In particular, an important issue in the prior approaches to this problem, the drive cycle dependence of the optimal policies, is alleviated. Within the basic framework, it is also possible to generate implementable operating policies that specify powertrain actuator settings as functions of engine operating conditions and states of the storage elements. We illustrate the procedure using an example powertrain with a Direct Injection Stratified Charge engine and an aftertreatment system consisting of a Three Way Catalyst and a Lean NOx Trap.
Target Cascading: A Design Process for Achieving Vehicle Ride and Handling Targets
Authors: Rideout D. Geoff , Stein Jeffrey L. , Ferris John B.
Published: November 2021

Vehicle dynamics are well understood by both academic researchers and automotive industries. And while modeling and simulation tools are still underutilized, they are becoming more frequently used in the vehicle design process. However, there is still lacking an overall design methodology that can link and integrate in a systematic fashion the design tasks of individual components or systems such that the vehicle performs as intended with a minimal number of design iterations. A process called Target Cascading, applied in the early stages of vehicle design, might serve as this systematic design methodology. In this paper, Target Cascading is evaluated for its ability to propagate top-level design specifications down to specifications for various subsystems and components in a vehicle design problem. More specifically, general ride and handling targets are set for a vehicle and these are cascaded down through the suspension, tire pressure and spring design levels by partitioning the original problem into a hierarchical set of subproblems. At a given level, an optimization problem is formulated to minimize deviations from the proposed targets and thus achieve intersystem compatibility. A coordination strategy links all subproblem decisions so that the overall supersystem performance targets are met. Results are presented that demonstrate Target Cascading’s utility in unearthing tradeoffs and incompatibilities among initial targets early in the vehicle development cycle. Throughout the paper, the Target Cascading process is compared to traditional vehicle design strategies for achieving ride and handling targets. Target Cascading appears to be a promising systematic technique for the design of vehicles to meet ride and handling specifications.
Should Adaptive Cruise Control (ACC) Systems Be Designed to Maintain a Constant Time-Gap Between Vehicles?
Authors: Wang Junmin , Rajamani Rajesh
Published: November 2021

This paper addresses the stability of traffic flow on a highway when the vehicles operate under an adaptive cruise control (ACC) system. ACC systems are commonly designed to maintain a constant time-gap between vehicles during vehicle following. Previous researchers in literature have produced contradictory results on whether the traffic flow is stable when the constant time gap spacing policy is used. This paper resolves the contradiction and shows that the boundary conditions used at the inlets and exits influence traffic flow stability in the case of the constant time-gap policy. Further, the paper shows that it is possible to design an unconditionally stable spacing policy, i.e. a spacing policy which guarantees traffic stability under all boundary conditions. The practical implications of instability are shown through traffic simulation results. The advantages of an unconditionally stable spacing policy over the constant time-gap policy are demonstrated. The answer to the question “Should ACC systems be designed to maintain a constant time gap between vehicles?” is NO. It is quite easy to develop alternate spacing policies with superior stability properties.
Networked Control of Distributed Systems: A Testbed
Authors: Stubbs Andrew , Dullerud Geir E.
Published: November 2021

A testbed for networked control of dynamical systems, recently developed by the authors at the University of Illinois, is described. It is comprised of planar aerial vehicles (hovercraft) which use the Bluetooth chipset for wireless communication, and inertial and vision sensing. The testbed is directly connected, via a Linux-based ground station, to a large Internet networking laboratory containing numerous routers, and thus the developed facility has the capability to model numerous wireless and Internet scenarios in networked control.
Stability Analysis of a Shape Memory Alloy Adaptive Tuned Vibration Absorber Under PI Control With Anti-Windup
Authors: Williams Keith A. , Chiu George , Bernhard Robert
Published: November 2021

This paper presents a stability analysis of a continuously controlled adaptive tuned vibration absorber (ATVA) incorporating shape memory alloy (SMA) structural elements to realize attenuation of the vibration of a primary system subject to uncertain tonal excitation. The objective is for the SMA ATVA stiffness to be adapted such that a relative phase angle of −90° is achieved between the vibration of the SMA ATVA and the primary mass. The Lyapunov-based stability analysis indicates that the system is stable under proportional-plus-integral control across the operating range of the SMA ATVA when an integral reset is included in the control algorithm. The integral reset also substantially improves the performance of the system when compared to the original PI controller without reset.
Active Balancing and Optimal Balancing Plane Selection of Rotors During Acceleration
Authors: Zhou Shiyu , Shin Kwang-keun , Dyer Stephen W. , Shi Jianjun , Ni Jun
Published: November 2021

This paper presents an active balancing method to reduce the imbalance-induced vibration of rotating machinery. In this method, the rotor was modeled by influence coefficient and a gain scheduling strategy was proposed to suppress the imbalance-induced vibration during acceleration. Besides the theoretical derivation of this active balancing algorithm, a comprehensive testbed was built to validate this scheme. The validation results were presented. To apply an active balancing scheme, the axial position of the actuator needs to be determined. This paper also presents an optimal balance plane selection procedure. A numerical study shows the effectiveness of this selection method.
The Active Control of Motion in a Composite Structure
Authors: Badea Traian , Chiroiu Veturia , Munteanu Ligia
Published: November 2021

The purpose of this paper is to propose a configuration for a piezoelectric composite structure that can control the motion caused by mechanical loads. The composite structure is composed of two semi-infinite layers: one layer of main material, and another layer of piezoelectric material with Cantor-like structure. We show that the displacement distribution can be controlled actively by applying a voltage to the piezoelectric material.
Disturbance Rejection Using Two Degree of Freedom Repetitive Control Through Mixed Sensitivity Optimization
Authors: Chen Cheng-Lun , Chiu George T.-C.
Published: November 2021

In this paper, a repetitive control based 2 degree-of-freedom (DOF) controller for a SISO motor/gear-train system is proposed. Instead of sequential design, it is shown that the optimal 2 DOF controller for such system can be obtained simultaneously by solving an mixed-sensitivity problem. The simulation results are presented to show the feasibility and effectiveness of the proposed control structure for periodic and non-periodic disturbance reduction for motor/gear-train velocity regulation.
State/Parameter/Disturbance Estimation With an Accelerometer in Precision Motion Control of a Linear Motor
Authors: Lee Dong-Jun , Tomizuka Masayoshi
Published: November 2021

In this paper, the use of an accelerometer in precision motion control of linear motors is investigated. The acceleration measurement can provide several advantages. In particular, it can be used with the position measurement for estimation of the position and velocity based on a kinematic model. It can be further utilized for identification of dynamic parameters such as coulomb friction and cogging force as well as for estimation of disturbance. Experimental results verify the effectiveness of the proposed estimation/identification schemes. These schemes are integrated into a two-degree of freedom control system for precision motion control of linear motors. The proposed schemes are evaluated by experiments performed on a linear permanent-magnet motor.
Logic Control Design and Implementation for a Machining Line Testbed Using Petri Nets
Authors: Gollapudi Chandra , Tilbury Dawn
Published: November 2021

Historically, logic control for machining systems has been programmed in ladder logic. Although this language is very intuitive at a low level, it is difficult to understand the sequencing in a large and complex program. Recently, several different formal languages, such as Petri nets, finite state machines, and real-time temporal logic, have been proposed for logic control design. These languages allow the logic to be formally verified to be correct before it is implemented. The proofs of correctness rely on a set of explicit and implicit assumptions. By implementing these methods on a testbed system, the advantages and limitations can be more easily seen. This paper describes an implementation of a formal method for logic control design using Petri nets on a small-scale testbed at the University of Michigan using software developed at the University of Kentucky.
Kinetostatic Behaviour of the Prismatic Pair With Clearance
Authors: Parenti-Castelli V. , Venanzi S.
Published: November 2021

In order to make mechanisms work the presence of clearance in kinematic pairs may be unavoidable. As a major consequence position and orientation errors of the output link occur when loads are applied to the mechanism. This paper focusses on the effect of clearance on the dislocation of the pairing elements of the prismatic pair. A kinetostatic model of the prismatic pair with clearance is presented and contact modes of the pairing elements are found. A particular geometry of the prismatic pair is considered to illustrate the proposed approach which can be used, in principle, for any pair geometry. The proposed model may be implemented in kinematic, kinetostatic and dynamic analyses as well, for the purpose of computing the influence of clearance on position-orientation errors of any link of the mechanism. Finally a numerical example is reported.
Investigation and Comparison of Possible Boundary Conditions and System Vibration Modes in Two-Link Flexible Manipulators
Authors: Cheong Joono , Youm Youngil , Chung Wan Kyun
Published: November 2021

In the slewing multi-link flexible robot systems, the natural frequencies and mode shapes have been determined using the assumed component mode method with clamped-joint condition, in which the system modes is reconstructed by the series of assumed modes of each link. This method, however, requires large number of assumed modes to accurately describe the system and even more, sometimes, the results are erroneous. The direct analytic solution of entire system vibration mode which is a comparative concept of assumed mode method can accurately account for the entire vibration with a few number of significant modes.

This paper deals with system vibration modes of two-link flexible robot and their appropriate boundary conditions. There are four possible set of boundary conditions, that is, clamped-clamped, clamped-spring, spring-clamped, spring-spring, according to joint servo condition, and we compare mode shapes and modal frequencies of each case by numerical and experimental results. We also provide important characteristics of natural mode when imposed certain kind of boundary conditions.
On the Use of the Level Set Method With Unstructured Grids
Authors: Shepel Sergey V. , Paolucci Samuel
Published: November 2021

A mass preserving finite element formulation of the Level Set method is presented. The formulation is based on the discontinuous representation of the level set function and involves the Runge-Kutta Discontinuous Galerkin (RKDG) finite element method. The resulting formulation has the flexibility of treating a complicated geometry by using arbitrary triangulation. The performance of the scheme is demonstrated on a number of two-dimensional re-distance and coupled advection-redistance problems. The results indicate that the RKDG finite element formulation provides accurate solutions of the Level Set problem and has great potential in fluid dynamics applications.
Numerical Simulation of Methane-Air Nozzle Burners for Aluminum Remelt Furnaces
Authors: Mukhopadhyay Achintya , Puri Ishwar K. , Zelepouga Serguei , Rue David M.
Published: November 2021

A turbulent nozzle-mix burner, suitable for industrial use in aluminum remelt furnaces has been numerically simulated using FLUENT software. The burner has been modeled as a vertical axisymmetric arrangement of fuel duct at the center, surrounded by a coaxial annular duct of air. The ducts discharge into a confined environment, formed by a chimney, placed coaxially with the ducts. The effects of fuel velocity and air coflow velocity ratio on the flame height have been investigated. The flame height is found to increase with increase in fuel velocity for a given air-fuel velocity ratio and with decrease in air velocity for a given fuel velocity. The different flame height definitions found in literature give nearly identical flame heights for all the cases studied.
Simulation of Multi-Phase Glass-Melt Flows in a Glass Melter
Authors: Chang S. L. , Zhou C. Q. , Golchert B. , Petrick M.
Published: November 2021

A typical glass furnace consists of a combustion space and a melter. The intense heat, generated from the combustion of fuel and air/oxygen in the combustion space, is transferred mainly by radiation to the melter where the melt sand and cullet (scrap glass) are melted, creating molten glass. The melter flow is a complex multi-phase flow including solid batches of sand/cullet and molten glass. Proper modeling of the flow patterns of the solid batch and liquid glass is a key to determining the glass quality and furnace efficiency. A multi-phase CFD code has been developed to simulate glass melter flow. It uses an Eulerian approach for both the solid batch and the liquid glass-melt flows. The mass, momentum, and energy conservation equations of the batch flow are used to solve for local batch particle number density, velocity, and temperature. In a similar manner, the conservation equations of mass, momentum, and energy of the glass-melt flow are used to solve for local liquid molten glass pressure, velocity, and temperature. The solid batch is melted on the top by the heat from the combustion space and from below by heat from the glass-melt flow. The heat transfer rate from the combustion space is calculated from a radiation model calculation while the heat transfer rate from the glass-melt flow to the solid batch is calculated from a model based on local particle number density and glass-melt temperature. Energy and mass are balanced between the batch and the glass-melt. Batch coverage is determined from local particle number density and velocity. A commercial-scale glass melter has been simulated at different operating/design conditions.
Temporally Resolved Radiation Spectra From a Sooting, Turbulent Pool Fire
Authors: Kearney Sean P.
Published: November 2021

Infrared radiation spectra from a 1-m diameter, JP-8-fueled, liquid pool fire in nominally quiescent surroundings have been acquired using a novel IR spectrometer. Data were acquired at a rate of 390 spectra/sec allowing for a time-resolved description of the radiation from the fully turbulent fire plume. Results are discussed in terms of an effective homogeneous pathlength and both gray and nongray spectral models, of which the gray model surprisingly fits the data in the soot-dominated regions of the spectrum more effectively. The results from the gray model are used to provide statistical descriptions of the heat transfer from the fire plume in terms of probability density functions (PDFs) of the effective fire temperature and emissivity.
Radiation Heat Transfer to the Leeward Side of a Massive Object Suspended Over a Pool Fire
Authors: Kramer M. Alex , Greiner Miles , Koski J. A.
Published: November 2021

A series of large-scale experiments were recently performed to measure heat transfer to a massive cylindrical calorimeter engulfed in a 30-minute circular-pool fire [1]. The calorimeter inner surface temperature was measured at several locations and an inverse conduction technique was used to determine the net heat flux. The flame emissive heat flux was measured at several locations around the calorimeter. Light winds of around 2 m/s blew across the calorimeter axis at the beginning of the test but diminished and stopped as the test continued. The winds tilted the fire so that the windward side of the calorimeter was only intermittently engulfed. As a result, the measured flame emissive power near the windward side was substantially less than the leeward surface. The variation of calorimeter temperature and heat flux was closely correlated with the measured flame emissive power.
Using Artificial Neural Networks to Develop a Predictive Method From Complex Experimental Heat Transfer Data
Authors: Kelleher Matthew D. , Cronley Thomas J. , Yang K. T. , Sen Mihir
Published: November 2021

Artificial neural networks are employed to develop a predictive algorithm using experimental heat transfer data for a complex situation. The data of Marto and Anderson has used to illustrate the process. This data is from a series of experiments investigating the boiling heat transfer from a vertical bank of tubes in refrigerant 114 with variable amounts of oil present. Both finned and unfinned tubes were investigated. The network was trained with a partial set of the available data. The prediction obtained using the trained network was then compared to the remaining experimental data. The artificial neural network provided an excellent predictive method.
Studies on Natural Convection Induced Flow and Thermal Behavior Inside Electronic Equipment Cabinet Model
Authors: Ishizuka Masaru , Peng Guoyi , Hayama Shinji
Published: November 2021

In the present work, an important basic flow phenomena, the natural convection induced flow, is studied numerically. Three-dimensional Navier-Stokes equations along with the temperature equation are solved on the basis of finite difference method. Generalized coordinate system is used so that sufficient grid resolution could be achieved in the body surface boundary layer region. Differential terms with respect to time are approximated by forward differences, diffusions terms are approximated by the implicit Euler form, convection terms in the Navier-Stokes equations are approximated by the third order upwind difference scheme. The heat flux at the body surface of heater is specified. The results of calculation showed a satisfactory agreement with the measured data and led to a good understanding of the overall flow and thermal behavior inside electronic equipment cabinet model which is very difficult, if not impossible, to gather by experiment.
A Simplified Numerical Model to Predict the Velocity Field in a Catalytic Cracking Unity in Oil Refineries
Authors: Souza J. A. , Vargas J. V. C. , von Meien O. F. , Vlassov D. I.
Published: November 2021

This paper introduces a general computational model for determining the velocity field in either reacting or non-reacting duct flows. The model is then applied to a catalytic cracking unit (FCC) of an oil refinery, to determine the velocity field inside the riser, where reactions take place to convert heavy petroleum fractions in lighter products, like middle distillates and light olefins, with high rates of conversion and productivity. The correct approach to simulate this process is to avoid the plug flow assumption and to solve the full fluid flow problem, based on the mass and momentum conservation equations in a complete formulation, which are shown in the literature to be computationally very expensive and time consuming, mainly in a three-dimensional (3-D) simulation. Since, the main objective of the simulation is the accurate determination of the concentration of the noble products, a very accurate velocity field is not mandatory. Therefore, bidimensional flow is assumed, and a modified set of unsteady mass and momentum conservation equations is proposed and the resulting 2-D differential equations are discretized in space using an upwind cell centered finite differences method, and the equations integrated in time with an implicit backward Euler scheme. The coarsest possible mesh is determined such that the solution relative error is within 5 % when compared to a steady state accurate finite element solution, which was obtained with a 2-D isoparametric, four-noded, linear element that was implemented to solve the complete Navier-Stokes equations for the finite element analysis program, FEAP [1]. The objective of this work is to propose an alternative technique that gives a simplified treatment to the velocity field, to make possible the numerical calculation of the products concentrations in the riser and future application in optimization and real time control. Each cell, in this specific situation, can be understood as a perfect mixing reactor.
Radiation and Induced Convection in Ventilated Enclosures
Authors: Ziskind G. , Dubovsky V. , Letan R.
Published: November 2021

The paper presents a thorough numerical investigation of the effects of radiation and induced convection inside an enclosure. The objective is to assess the interaction of these two mechanisms in real size buildings with heating elements inside.

As a first step, a small size model is studied. The investigation is performed for closed and partially open enclosures. Temperature distributions and flow fields inside the enclosure are obtained for different values of the heat-transfer parameters, like emissivity of the hot element and the walls, and the thermal resistance of the walls. It is shown that radiation can considerably affect the air flow inside the enclosure. Real-size structures, where turbulent flow prevails, are compared to the model.

Three-dimensional simulations are performed. The influence of grid refinement on the results is discussed. The results obtained for a uniform grid are compared to those for a non-uniform one, having higher density at the boundaries. Special attention is paid to the radiation modeling, where the influence of angular discretization is important.
Quantitative Validation of Mathematical Models
Authors: Dowding Kevin
Published: November 2021

Validation is a process to compare a mathematical model with a set of physical experiment to quantify the accuracy of the model to represent the physical world (experiment). Because the goal is to use experiments to quantify the accuracy of the mathematical model, the interaction of the model and experiment must be carefully studied. Advancing the comparison beyond a qualitative nature requires consideration of the errors in the process and the effect of these errors on the comparison. The mathematical model, in conjunction with sensitivity analysis, uncertainty analysis, and statistical analysis are tools for studying the interaction of the model and experiment and quantifying the effect of errors. A model for steady state heat conduction is used to discuss issues associated with the errors in the validation process and demonstrate a quantitative process to study validation of mathematical models.
Simultaneous Determination of Steady Temperatures and Heat Fluxes on Surfaces of Three Dimensional Objects Using FEM
Authors: Dennis Brian H. , Dulikravich George S.
Published: November 2021

A finite element method (FEM) formulation is presented for the prediction of unknown steady boundary conditions in heat conduction on multiply connected three-dimensional solid objects. The present FEM formulation is capable of determining temperatures and heat fluxes on the boundaries where such quantities are unknown or inaccessible, provided such quantities are sufficiently over-specified on other boundaries. Details of the discretization, linear system solution techniques, regularization, and sample results for 3-D problems are presented.
Experimental Investigation of Local Heat Transfer Distribution on Smooth and Roughened Surfaces Under an Array of Angled Impinging Jets
Authors: El-Gabry Lamyaa A. , Kaminski Deborah A.
Published: November 2021

Measurements of the local heat transfer distribution on smooth and roughened surfaces under an array of angled impinging jets are presented. The test rig is designed to simulate impingement with cross-flow in one direction which is a common method for cooling gas turbine components such as the combustion liner. Jet angle is varied between 30, 60, and 90 degrees as measured from the impingement surface, which is either smooth or randomly roughened. Liquid crystal video thermography is used to capture surface temperature data at five different jet Reynolds numbers ranging between 15,000 and 35,000. The effect of jet angle, Reynolds number, gap, and surface roughness on heat transfer efficiency and pressure loss is determined along with the various interactions among these parameters.

Peak heat transfer coefficients for the range of Reynolds number from 15,000 to 35,000 are highest for orthogonal jets impinging on roughened surface; peak Nu values for this configuration ranged from 88 to 165 depending on Reynolds number. The ratio of peak to average Nu is lowest for 30-degree jets impinging on roughened surfaces. It is often desirable to minimize this ratio in order to decrease thermal gradients, which could lead to thermal fatigue. High thermal stress can significantly reduce the useful life of engineering components and machinery. Peak heat transfer coefficients decay in the cross-flow direction by close to 24% over a dimensionless length of 20. The decrease of spanwise average Nu in the crossflow direction is lowest for the case of 30-degree jets impinging on a roughened surface where the decrease was less than 3%. The decrease is greatest for 30-degree jet impingement on a smooth surface where the stagnation point Nu decreased by more than 23% for some Reynolds numbers.
Analysis of Heat Exchanger Concepts for Use As Gas Turbine Intercoolers
Authors: Saidi Arash , Eriksson Daniel , Sundén Bengt
Published: November 2021

This paper presents a discussion and comparison of some heat exchanger types readily applicable to use as intercoolers in gas turbine systems. The present study concerns a heat duty of the intercooler for a gas turbine of around 17 MW power output. Four different types of air-water heat exchangers are considered. This selection is motivated because of the practical aspects of the problem. Each configuration is discussed and explained, regarding advantages and disadvantages. The available literature on the pressure drop and heat transfer correlations is used to determine the thermal-hydraulic performance of the various heat exchangers. Then a comparison of the intercooler core volume, weight, pressure drop is presented.
Dimple Enhanced Heat Transfer in High Aspect Ratio Channels
Authors: Ekkad Srinath V. , Nasir Hasan
Published: November 2021

Detailed heat transfer measurements are presented for a rectangular channel with dimples on one wall. Dimpled surfaces provide high heat transfer enhancement comparable to ribbed surfaces with reduced overall pressure drop. The heat transfer coefficients were measured using a transient liquid crystal technique. The effect of channel flow Reynolds number was investigated for a wide range from 10000 to 65000. The channel is a 25.4 mm × 101.6 mm (1” × 4”) rectangular cross-section with the dimples on one of the 101.6 mm wall. Heat transfer enhancement around three times that of a smooth channel were achieved for all flow conditions. The overall pressure drop through the dimpled section of the passage was also measured. The resulting thermal performance of the dimples surfaces is significantly higher compared to channels with protruding ribs.
Investigation of Polymer Based Micro Heat Pipes for a Flexible Spacecraft Radiator
Authors: McDaniels D. , Peterson G. P. “Bud”
Published: November 2021

In response to the space industry’s pursuit of interplanetary travel and a continuous human presence in space, there is increasing focus on spacecraft that change configuration while in space. Flexible thermal radiators are being developed to accommodate various collapse and deployment mechanisms. An analytical model suggests that a lightweight polymeric material with imbedded micro heat pipe arrays can meet heat dissipation requirements while contributing less mass than competing flexible materials. The capillary pumping limit is evaluated as a function of operating temperature using two candidate working fluids. Using water, the maximum heat transport is 18 mW per channel at 140/160 °C. The maximum heat transport using methanol is 2.2 mW at 120 °C, an order-of magnitude difference. A thermal circuit model translates heat transport per channel into total radiator capacity as a function of source temperature and environmental sink temperature. Using water as the working fluid, the radiator capacity was shown to vary from 6.0 kW to 12.2 kW for source temperatures of 20 °C to 50 °C. For source temperatures of 40 °C and higher, the capacity meets or exceeds the dissipation requirements of a reference spacecraft design.

While evaluated, methanol is not recommended as a working fluid because its radiator capacity is two to three times lower than water. Although thermal system constraints place limits on the micro heat pipe operating range, design changes directed at alleviating capillary limitations should increase radiator capacity. Technical issues for further study include effects of film billowing, performance limitations related to vapor viscosity, working fluid diffusion, and chemical reactivity between case and working fluid. Compared to a competing graphite fiber weave, the polymeric material has an effective conductivity over ten times higher. Its area power density (in kW/m2) is 18% to 60% lower than the graphite weave, but its mass power density (in kW/kg) is several times higher. Greater flexibility and lower weight also make it more amenable to structural integration. Recently developed space-stable polymers offer resistance to harsh temperature and radiation environments, helping to clear the path toward a more extensive use of polymers within the space industry.