bluuebunny/crossref_metadata_2025 huggingface dataset:
International veterinary canine dyskinesia task force ECVN consensus statement: Terminology and classification
Authors: Cerda‐Gonzalez Sofia , Packer Rebecca A. , Garosi Laurent , Lowrie Mark , Mandigers Paul J. J. , O'Brien Dennis P. , Volk Holger A.
Published: March 2021

Movement disorders are a heterogeneous group of clinical syndromes in humans and animals characterized by involuntary movements without changes in consciousness. Canine movement disorders broadly include tremors, peripheral nerve hyperexcitability disorders, paroxysmal dyskinesia, and dystonia. Of these, canine paroxysmal dyskinesias remain one of the more difficult to identify and characterize in dogs. Canine paroxysmal dyskinesias include an array of movement disorders in which there is a recurrent episode of abnormal, involuntary, movement. In this consensus statement, we recommend standard terminology for describing the various movement disorders with an emphasis on paroxysmal dyskinesia, as well as a preliminary classification and clinical approach to reporting cases. In the clinical approach to movement disorders, we recommend categorizing movements into hyperkinetic vs hypokinetic, paroxysmal vs persistent, exercise‐induced vs not related to exercise, using a detailed description of movements using the recommended terminology presented here, differentiating movement disorders vs other differential diagnoses, and then finally, determining whether the paroxysmal dyskinesia is due to either inherited or acquired etiologies. This consensus statement represents a starting point for consistent reporting of clinical descriptions and terminology associated with canine movement disorders, with additional focus on paroxysmal dyskinesia. With consistent reporting and identification of additional genetic mutations responsible for these disorders, our understanding of the phenotype, genotype, and pathophysiology will continue to develop and inform further modification of these recommendations.
A retrospective validation of different scores of guideline adherence and infectious diseases consultation on candidaemia: The higher, the better
Authors: Calderón‐Parra Jorge , Herraiz‐Jiménez Jesus , Ramos‐Martínez Antonio , Muñez‐Rubio Elena , Callejas‐Diaz Alejandro , Diaz de Santiago Alberto , Sánchez‐Romero Isabel , López‐Dosil Marcos , Fernández‐Cruz Ana
Published: March 2021

Background

Recently, several scores to quantify compliance with the guidelines in candidaemia management (EQUAL, GEMICOMED, Valerio) have been developed. Evidence supporting the association of these scores to the prognosis is scarce. We aim to evaluate the performance of these candidaemia guideline adherence scores to predict candidaemia outcome.

Methods

We recorded retrospectively data from candidaemia episodes (January 2017‐December 2018). We analysed adherence to guidelines for candidaemia management according to EQUAL, GEMICOMED and Valerio scores, and we correlated those to outcome.

Results

Fifty‐four first episodes of candidaemia were retrieved. Five patients who died in the first 48 hours after blood cultures were not included. Thirty‐day mortality in evaluable patients was 18.4%. Median adherence to guidelines according to EQUAL score was 17 (interquartile range [IQR]: 15‐19), and according to GEMICOMED was 86% (IQR: 72.5%‐100%). According to Valerio score, adequacy of antifungal prescription was 8.5/10 (SD: 1.9). A cut‐off of ≥17 for EQUAL or compliance >70% for GEMICOMED was associated with inferior 30‐day mortality (7.1% vs 33.3%, P = .028 and 7.9% vs 54.5%, P = .002, respectively). Infectious diseases (ID) evaluated cases obtained a better EQUAL score (>17; 82.1% vs 42.9%, P = .006), had inferior 30‐day mortality (9.4% vs 35.3%, P = .049) and a better antifungal prescription adequacy (Valerio score 9.0 vs 7.5, P = .011).

Conclusion

Adherence to guidelines for candidaemia management evaluated by means of EQUAL and GEMICOMED score was associated with a decreased 30‐day mortality. Adequacy of antifungal prescription can be ameliorated. ID consultation improved guideline adherence and was associated with decreased 30‐day mortality.
Medical adhesive‐related skin injuries in the neonatology department of a teaching hospital
Authors: de Oliveira Marcatto Juliana , Santos André Soares , Oliveira Ananda Jéssyla Felix , Costa Anna Caroline Leite , Regne Giulia Ribeiro Schettino , da Trindade Raquel Elias , Couto Débora Lara , de Souza Noronha Kenya Valéria Micaela , Andrade Mônica Viegas
Published: March 2021

Background

Medical adhesives are used to affix components to the skin. They are part of procedures performed by medical specialties because of their participation as constituents of different products, such as tapes, dressings, and electrodes.

Aim

This study aims to assess the prevalence of, and factors associated with, the development of medical adhesive‐related skin injuries (MARSIs) in patients treated with medical tapes in the neonatology department of a large teaching hospital in Brazil.

Study Design

Cohort study.

Methods

All premature newborns (gestational age from 28 to <37 weeks) admitted in the neonatal intensive care unit of a teaching hospital, from March to August 2019, were followed up. Neonate skin condition was assessed based on the Neonatal Skin Condition Scale (NSCS). Data analyses were conducted in R software.

Results

In total, 46 premature newborns were included in the study; 552 evaluations were performed—mean of 11.7 per patient. Most neonates (n = 41; 89.1%) used adhesive tapes, either paper tape (n = 37; 80.4%) or transparent film dressing (n = 34; 73.9%). Newborns' face and head were the most affected body regions (n = 125; 50.2%). Eight patients had MARSIs (19.5% of patients who used tape). NSCS scores (P value <.001) and the adopted warming system (P value = .01302) were associated with the occurrence of MARSIs. Incubators seem to be a protective factor for MARSI (OR = 0.048; IC95% = 0.0008‐0.75; P value = .013).

Conclusion

Adhesive tapes in premature newborns should be considered a risk factor for injuries. Although NSCS showed mild‐to‐moderate impairment and lesion severity was low, this event is relatively frequent in neonatal units.

Relevance to Clinical Practice

Awareness of the risk associated with adhesive tape application and removal in newborns allow health services to better address the problem by enforcing good practices, elaborating better protocols, qualifying the health care professionals, and potentially selecting softer tapes for neonates.
Incentive Provision in Light of Expertise and Operational Involvement of Angel Investors
Authors: Arya Anil , Mittendorf Brian , Pfeiffer Thomas
Published: March 2021

Angel investors provide a unique role in startup entities: in addition to providing financing, they also provide expertise and make critical operational and managerial decisions. As a result, a startup not only seeks funding from its angel investor, but also strives to ensure that their expertise promotes entrepreneurial success. This study formalizes a model of optimal equity sharing with angel investors in light of the facts that (i) they have private information about their expertise, (ii) the expertise impacts the efficacy of subsequent operating decisions, and (iii) equity sharing alters control rights linked to these decisions. We demonstrate that an entrepreneur will exhibit seemingly excessive optimism in decision‐making when angel investors claim they bring high expertise (skills) to the table. This apparent optimism is not a sign of naiveté but rather an effective device to discipline boasting by angels. The results demonstrate the critical role of expertise and decision rights in constructing ownership‐sharing agreements with angel investors. They also demonstrate a case in which the private information of investors (rather than that of insiders) is important, and how such adverse selection concerns entail aggressive operational choices, rather than the typical response of caution, coupled with limited equity usage that accounts for not just the transfer of ownership, but also the transfer of decision rights.
Managing the Inter‐Functional Tension between Accounting‐ and Financial‐Profits in Remanufacturing Multiple‐Usecycle Products
Authors: Mutha Akshay , Bansal Saurabh , Guide V. Daniel R.
Published: March 2021

We investigate the tension between accounting and financial functions of an OEM who manufactures and remanufactures capital‐intensive products. The OEM operates a servicizing business model in which it leases a product, remanufactures the product returned at the end of the lease, and re‐leases the remanufactured product ( usecycle), with multiple such usecycles. The accounting function at the firm would suggest that the OEM: (i) recovers the initial manufacturing cost of the product over its useful life as prescribed by IRS guidelines via depreciation; (ii) remanufactures the product as long as its initial manufacturing cost is not fully recovered; and (iii) removes the product from the books immediately after it has completely depreciated. In contrast, the financial function would consider the initial manufacturing cost of the product to be a sunk cost and would suggest that the firm continues to remanufacture the product as long as the remanufacturing cost is lower than the cost of a new unit. In this study, we investigate and prescribe ways to resolve this tension using analytical models. Specifically, we first show that the optimal durations over which the product should be used and lease prices that maximize the OEM's accounting profit and financial profit are different. We then discuss two operational approaches to align the accounting and operational perspectives while following IRS guidelines. Finally, informed by this analysis, we develop policy prescriptions to promote remanufacturing of multiple usecycle products. Overall, this analysis highlights the role of regulatory guidelines on remanufacturing operations and the inter‐functional effort required by OEMs to successfully integrate remanufacturing operations in their business strategy.
Excessive Competition and Supplier Non‐Performance Risk: Trade‐offs in Reverse Auctions
Authors: Chaturvedi Aadhaar
Published: March 2021

Supplier non‐performance is an ever present problem for an original equipment manufacturer (OEM) buyer and past survey‐based research has shown that increasing supplier competition adversely affects their performance. Using a reverse auction setting in which supplier competition is determined by number ( n) of participating suppliers (bidders), we show how buyer's exposure to supplier non‐performance risk is influenced by n. In particular, we characterize conditions under which supplier non‐performance risk is increasing in n. We then formulate a buyer's decision on the optimal n for uniformly distributed costs that allows it to resolve its cost vs. risk trade‐off. We further investigate other strategies like dual sourcing, better screening, and lower threshold on acceptable bids, that the buyer can use, together with limiting n, to limit non‐performance risk and control its overall procurement cost. Managerially, our findings indicate that an OEM buyer procuring non‐strategic (non‐critical) components could increase its exposure to supplier non‐performance risk by leveraging too much competition, especially among small entrant suppliers. In such situations a buyer can manage its input cost and risk by limiting supplier competition.
Behavioral and electroencephalographic evidence for reduced attentional control and performance monitoring in boredom
Authors: Yakobi Ofir , Boylan James , Danckert James
Published: March 2021

Boredom, the unfulfilled desire to be engaged in a satisfying mental activity, is an aversive state characterized by poor self‐regulation. There is ample evidence that both state and trait boredom are associated with failures of attention in both experimental and everyday settings. The neural correlates of boredom, however, remain underexplored. We recorded electroencephalographic signal from 83 participants during a resting state and while performing a go/no‐go task. We found a negative correlation between trait boredom proneness and power in the alpha and theta bands during the resting state. Furthermore, higher levels of task‐induced boredom were associated with reduced amplitudes for the P3 and error‐related negativity event‐related potentials. Increased commission error rates were also associated with higher levels of task‐induced boredom. We conclude that state and trait boredom are associated with inadequate engagement of attentional resources.
Breakthrough invasive fungal infection after liver transplantation in patients on targeted antifungal prophylaxis: A prospective multicentre study
Authors: Rinaldi Matteo , Bartoletti Michele , Ferrarese Alberto , Franceschini Erica , Campoli Caterina , Coladonato Simona , Pascale Renato , Tedeschi Sara , Gatti Milo , Cricca Monica , Ambretti Simone , Siniscalchi Antonio , Morelli Maria Cristina , Cescon Matteo , Cillo Umberto , Di Benedetto Fabrizio , Burra Patrizia , Mussini Cristina , Cristini Francesco , Lewis Russell , Viale Pierluigi , Giannella Maddalena
Published: March 2021

Objective

To investigate the rate of and the risk factors for breakthrough‐IFI (b‐IFI) after orthotopic liver transplantation (OLT) according to the new definition proposed by Mycoses‐Study‐Group‐Education‐and‐Research‐Consortium (MSG‐ERC) and the European‐Confederation‐of‐Medical‐Mycology (ECMM).

Methods

Multicenter prospective study of adult patients who underwent OLT at three Italian hospitals, from January 2015 to December 2018. Targeted antifungal prophylaxis (TAP) protocol was developed and shared among participating centers. Follow‐up was 1‐year after OLT. B‐IFI was defined as infection occurring during exposure to antifungal prophylaxis. Risk factors for b‐IFI were analyzed among patients exposed to prophylaxis by univariable analysis.

Results

We enrolled 485 OLT patients. Overall compliance to TAP protocol was 64.3%, 220 patients received antifungal prophylaxis, 172 according to TAP protocol. Twenty‐nine patients were diagnosed of IFI within 1 year after OLT. Of them, 11 presented with b‐IFI within 17 (IQR 11‐33) and 16 (IQR 4‐30) days from OLT and from antifungal onset, respectively. Then out of 11 patients with b‐IFI were classified as having high risk of IFI and were receiving anti‐mould prophylaxis, nine with echinocandins and one with polyenes. Comparison of patients with and without b‐IFI showed significant differences for prior Candida colonization, need of renal replacement therapy after OLT, re‐operation, and CMV infection (whole blood CMV‐DNA >100 000 copies/mL). Although non‐significant, a higher rate of b‐IFI in patients on echinocandins was observed (8.2% vs 1.8%, P = .06).

Conclusions

We observed 5% of b‐IFI among OLT patients exposed to antifungal prophylaxis. The impact of echinocandins on b‐IFI risk in this setting should be further explored.
Histologic evidence for a humoral immune response in synovitis associated with cranial cruciate ligament disease in dogs
Authors: Kuroki Keiichi , Williams Ned , Cook James L.
Published: March 2021

Objective

To investigate histopathological features of synovium from dogs with cranial cruciate ligament disease (CCLD) to seek mechanisms of osteoarthritis (OA) associated with CCLD.

Study design

Retrospective, single‐institution case series.

Animals

Thirty client‐owned dogs.

Methods

Synovial biopsies (n = 30) obtained from stifles with CCLD were assessed by using two synovitis histopathology grading systems (Krenn and Hospital for Special Surgery [HSS]). The Krenn synovitis score was interpreted as “no synovitis,” “low‐grade,” or “high‐grade,” while inflammatory subtype (low, mixed, or high) was determined by a computational algorithm within the HSS system. Comparison of synovitis scores was based on degree of CCL rupture and presence of meniscal tears.

Results

Histopathological changes and synovitis scores were similar regardless of degree of rupture (partial n = 5, complete n = 25) or presence of meniscal injury (n = 12) and were characterized by hyperplastic and lymphoplasmacytic synovitis with increased vascularity (30/30) and the presence of hemosiderin deposits (28/30), binucleated plasma cells (28/30), mucoid change (25/30), and Mott cells (16/30). Thirteen (43%) specimens were consistent with high‐grade synovitis according to the Krenn system, while 11 (37%) specimens fit into the high‐inflammatory subtype with the HSS system.

Conclusion

Synovitis associated with canine CCLD in this study population was lymphoplasmacytic and was often highly inflammatory, with the presence of cells pertaining to humoral immunity. Humoral immune responses may play key roles in the synovitis associated with CCLD.

Clinical significance

Modulation of biological factors that provoke humoral immune responses may mitigate symptoms of OA that persist and progress even after surgical treatment of CCLD in dogs.
A Potential Framework for CAD/CAE/CIM Decisions
Authors: Main Bruce W. , Ward Allen C.
Published: March 2021

This paper outlines some common problem categories taken from the literature in implementing company-wide computer integration. These problem categories form a framework for making CAD/CAE/CIM decisions. The framework addresses the following problem categories: detrimental impacts of computerization systems on design creativity, difficulties with CAD communications, inhibiting effects on continual improvement, problems of computerizational integration preceding organizational integration, and process-driven versus need-based computer integration efforts. The framework may assist CAD/CAE/CIM decision makers with their integration efforts.
Design for Serviceability Expert System
Authors: Bryan Christopher , Eubanks Charles , Ishii Kosuke
Published: March 2021

This paper describes a methodology and tool which assist deployment of serviceability in the early stages of life-cycle design. Unlike design for assembly, producability, etc., design for serviceability (DFS) commonly occurs in the later stages of the design process. By this time, any design changes required to enhance serviceability are either costly or infeasible. We have developed a graphics-based computer tool to be used early in the design phase that employs the concept of service mode analysis (SMA), coupled with a service-based design description, to assess the impact of component relationships on life-cycle service costs. We also employ design compatibility analysis (DCA) to assess qualitative aspects of the design for serviceability concerns and provide the user with comments and suggestions for design improvements. Significant reductions in life-cycle costs and significant improvements in customer satisfaction can be achieved by including DFS in the design trade-off analysis process.
The Optimal Design of a Multi-Axis Load Transducer
Authors: Wickham Mary J. , Riley Donald R. , Nachtsheim Christopher J.
Published: March 2021

The determination of loads applied to a structure is often necessary in the design process. In some situations it is not feasible to insert a load cell in the system to measure these applied loads. In these cases, it would be expedient to utilize the structure itself as a load transducer. This can be accomplished by measuring strains at a number of locations on the structure.

The precision with which the applied loads can be estimated from measured structural responses depends on the number of strain gages utilized and their placement on the structure. This paper presents a computational methodology which utilizes optimal experimental design techniques to select the number, locations and angular orientations of the strain gages which will provide the most precise load estimates based on the generalized load vector. Selection is made from a candidate set created using a finite element analysis. This method is illustrated with an experimental application example.
Elements of a Software Architecture for a Rapid Prototype Test and Evaluation System for Experimental Structural Dynamics
Authors: West Robert L. , Wang Wei
Published: March 2021

This paper presents work in progress toward the development of a test and evaluation system for a new concept in experimental structural dynamics. Structural imaging is composed of both the static and dynamic image of the structure, resulting in the structure’s profile and dynamic response. Structural imaging is realized by interfacing a scanning laser velocimeter to an engineering workstation for data acquisition, signal processing, data modeling and scientific visualization. A software system is to be developed that will allow the investigation of the science and the rapid-prototyping and evaluation of new methods.

The design goals for the system software are presented. The concepts defining the elements of the software architecture are also discussed. The event driven finite state machine is explored as the fundamental model of the system architecture. Run-time configuration of the software and virtual instruments provides a mechanism for the evolution of the system. The concepts of the project and test objects are introduced to support the testing of structures. Issues of systems integration and system objects for handling errors and files are also discussed.
Analysis of Complex Geometric Tolerances by Linear Programming
Authors: Martino Peter
Published: March 2021

This paper presents an extension of the linear programming tolerance analysis method introduced by Turner. The new techniques are suited to the analysis of complex geometric tolerances: tolerances involving non-planar datums, tolerance material conditions, and datum material conditions.

Key features of the new method are -

* Ability to model a wide range of tolerance datums.

* Datums, as well as tolerances, are represented by linear program constraints.

* Rigid body motion degrees of freedom, as well as dimensions (or model variables), are linear program variables.

* The linear program is solved by a special three phase simplex method.

The new techniques are intended to be used in computer aided tolerance analysis systems.
Minimizing Drag Coefficients Using Bezier Technique
Authors: Bata Reda , Katragadda Sunil , Churchill Randolph , Wang Wenguang
Published: March 2021

Optimizing the profile design of a vehicle body for minimum drag coefficient can have a beneficial impact upon the vehicle performance, energy conservation, and exhaust gas emissions. An interactive technique based on the fundamental concepts of Bezier equations was utilized to develop the body profile and its corresponding drag coefficient. The technique described could be used by automobiles, submarines, and aircraft designers. Since the technique is interactive, the profile can be changed and tested again, allowing flexibility to produce the desired shape for the designer. The cubic four point Bezier curve utilizes four control points of which the two end points are fixed to the curve and the other two are used to interpolate the smooth profile. The governing principles of aerodynamics are used to develop the algorithm for the optimization process. A feature of this algorithm is that it accounts for the turbulence of the wind at its interface with the structure.
Thermal Analysis of Air-Cooled Electronic Equipment
Authors: Sharaf-Eldeen Y. I. , Rengarajan Kannan
Published: March 2021

Owing to the increasing miniaturization and number of high-power-dissipating components in electronic packages, proper thermal management has become of vital importance. Numerical simulations were carried for three block-type elements representing electronic components located on the bottom plate of a rectangular channel. The top plate of the channel was parametrically examined in order to assess the radiative heat-transfer component. The effects of the air flow rate in the channel and the spacing, geometry, and emissivity of the blocks were investigated. Two types of heat sources were considered: A uniform heat-generation rate in each block and a point heat-source at the center of each block. Reynolds numbers varying from 10 to 1000 and block length-to-spacing ratio varying from 1 to 3.7 were considered in this work. The results clearly indicate that, when the radiative heat-transfer component is neglected, 33% of the heat generated is conducted through the bottom substrate while the remaining 67% is convected to the cooling medium. However, when the radiative heat transfer is considered in the analysis, the radiant heat loss is estimated to range from 4 to 8%, at a Reynolds number of 500.
An Implementation of Monitoring Systems Using Microprocessor Building Blocks
Authors: Li Qiang , Yip T. Gary
Published: March 2021

This paper presents a cost-effective implementation of a sensor monitoring system based on microprocessor building blocks. The Inmost Transputer processor is selected as the building block model. Some possible configurations of the system is discussed. Since further detailed study is needed, the paper serves as a preliminary study report.
Natural Convection-Radiation Induced Flows of Air Over a Horizontal Plate
Authors: Chuang H.
Published: March 2021

Combined effects of natural convection and radiation on a laminar boundary-layer flow over a semi-infinite horizontal flat plate are studied. Increasing the natural convection-radiation interaction in the boundary layer increases the shearing stress on the wall, the boundary-layer thickness, the maximum velocity attainable by fluid, and the buoyancy force in the boundary layer. However, the temperature gradient at the plate decreases with increasing interaction. They generally increase with increasing temperature ratio. Automated computations of the dimensionless velocity, temperature, and buoyancy force in the boundary layer yield convergent solutions which are substantially different from those available in the literature for high natural convection-radiation interactions.
Design Optimization of a Packing Material Using Finite Element Techniques
Authors: Lamba Sukhwinder S. , Rhodes Curtis A.
Published: March 2021

This paper presents size and shape optimization of a recyclable packing material. Shell thickness and shape was optimized to prevent contact of surfaces within the packing material. Thus optimization was used to improve cushioning characteristics of the packing material.
Characterization of Modal Coupling in Nonclassically Damped Systems
Authors: Ma F. , Park I. W. , Kim J. S.
Published: March 2021

A common procedure in the solution of a nonclassically damped linear system is to neglect the off-diagonal elements of the associated damping matrix. For a large-scale system, substantial reduction in computational effort is achieved by this method of decoupling the system. Clearly, the decoupling approximation is valid only if modal coupling can somehow be neglected. The purpose of this paper is to study the characteristics of modal coupling, which is amenable to a complex representation. An analytical formulation that facilitates the evaluation of modal coupling is developed. Contrary to widely accepted beliefs, it is shown that neither frequency separation of the natural modes nor strong diagonal dominance of the modal damping matrix would be sufficient to suppress the sometimes significant effect of modal coupling.
Robust Mesh Generation for Areas With Advancing Boundaries
Authors: Clifton Rodney J. , Wang Jian-Juei
Published: March 2021

This paper presents an adaptive optimal mesh generator, including criteria for determining the boundary nodal coordinates. This mesh generator has been developed to provide mesh for a planar fracture surface in the three-dimensional simulation of hydraulic fracturing. The mesh generator is based on the optimization of the local aspect ratio by minimizing the difference of the principal stretches in mapping a square reference mesh onto the fracture surface. Sector areas, curvatures along the fracture boundary, and the locations of the corner nodes are used to calculate weights in determining the locations of the boundary nodes of the advancing fracture surface. Hydraulic fracturing simulation examples of various meshes are presented with discussion of the weighing parameters used in locating the boundary nodes.
Four-Boundary Grid Generation for Time-Varying Spatial Domains
Authors: Yang S. L. , Ho M. J.
Published: March 2021

A 2D algebraic grid generation technique is presented for generating grid points for time-varying and irregular spatial domains. The method is based on the “four-boundary technique” of Vinokur and Lombard (1983) and is an extension of the “two-boundary technique for time-varying spatial domains” method developed by Yang and Shih (1986). Since it is an algebraic approach, the method is very efficient and can easily be extended to time-varying 3D spatial domains.

To show the feasibility and the usefulness of the grid generation technique, (1) it is applied to the problem of generating grids for the combustion chamber above an internal combustion engine piston with bowl-in-cavity, and (2) numerical solutions are obtained for the fluid motion in the combustion chamber for intake and compression strokes.
A Three-Dimensional Algebraic Grid Generation Scheme for Gas Turbine Combustors With Inclined Slots
Authors: Yang S. L. , Cline M. C. , Chen R. , Chang Y.-L.
Published: March 2021

A 3D algebraic grid generation scheme is presented for generating the grid points inside gas turbine combustors with inclined slots. The scheme is based on the 2D transfinite interpolation method. Since the scheme is a 2D approach, it is very efficient and can be easily extended to gas turbine combustors with either dilution hole or slot configurations.

To demonstrate the feasibility and the usefulness of the technique, a numerical study of the quick-quench/lean-combustion (QQ/LC) zones of a staged turbine combustor is given. Preliminary results illustrate some of the major features of the flow and temperature fields in the QQ/LC zones. Formation of co- and counter-rotating bulk flow and sandwiched-ring-shape temperature fields, typical of the confined slanted jet-in-cross flow, can be observed clearly. Numerical solutions show the method to be an efficient and reliable tool for generating computational grids for analyzing gas turbine combustors with slanted slots.
Compressive Response of Thermoplastic Composites by Layered Shell Elements
Authors: Mahfuz Hassan , Ingram Cynthia R. , Jeelani Shaik
Published: March 2021

Thick Laminates of thermoplastic Composites (APC-2) are modeled with isoparametric layered shell elements to predict the responses of the laminate at various temperatures under compressive loading. A large displacement finite element analysis is performed by considering the geometric non-linearities in the composite structure. Multiple load steps with linear material behavior are used to model the load-displacement characteristics found in a previous experimental study. A detailed description of the layered shell element along with its formulations is presented to highlight the limitations and scope of this element in composite structural analysis. Compressive response in respect of displacements, normal stresses, shear stresses and interlaminar shear stresses under three different temperatures is presented. Laminate response along its length as well as through the thickness is also presented to analyze and understand the failure mechanisms under such loading. Experimental data from a previous study are compared with the current result to validate the finite element analysis.
Computer Simulation of Axial Stress Wave System in Finite-Length Specimens
Authors: Prucz Jacky C.
Published: March 2021

A complete damping-stiffness characterization of a given medium can be derived from the development of a propagating stress pulse between two fixed locations. The extensional stiffness is determined by the phase velocity, whereas the damping is measured by the pulse attenuation [1]. Thus far this approach has been limited to axial impact of long, slender rods. The multiple frequency content of a rectangular-pulse restricts the test specimens to slender rods or fibers in order to avoid pulse dispersion as a result of lateral inertia effects [2]. An improved stress pulse method for more realistic damping measurements in a broader range of test specimens has been developed recently [3]. It is referred to as the “Sine-Pulse Propagation” technique since the commonly used impact pulse is replaced by a sine-shaped pulse, which usually contains one full cycle. Its main advantage as compared to traditional methods for damping characterization, such as the “Hysteresis Loop” approach, is that it minimizes the loss of vibratory energy in the testing apparatus, which is the main contaminating form of conventional damping data [4].
Application of Fracture Mechanics to Surface Imperfections in Castings
Authors: Cheng Wing L. , Bigelow Erick
Published: March 2021

Allowable sizes of surface imperfections were determined for different regions of a casting that is subjected to cyclic loading. Finite element analysis was used to determine the nominal stresses throughout various sections of the casting. The accumulative damage in terms of crack growth rate from potential surface defects was calculated based on the stresses resulted. A novel approach based on fracture mechanics was applied to treat linear defects in the casting. The cumulative damage in the subcritical crack growth regime was determined using the Paris Crack Growth Law. For the standard cast material, a simplified fracture criterion was selected to determine ultimate failure. At regions where surface hardening heat treatment was specified, ultimate failure occurred due to unstable crack growth therefore a brittle fracture criterion was applied. Results obtained from this analysis have provided a basis for determination of inspection criteria for linear discontinuities.
Integrated Pipe Stress Analysis/Support Pattern Selection/Support Design CAE System
Authors: Chatterjee M. , Unemori A. , Kakaria A. , Jain D.
Published: March 2021

This paper describes the organization and features of the AUTO-PIPE CAE System. AUTO-PIPE is a fully integrated software package which allows the User to perform the entire sequence of piping analysis and design in a streamlined work flow process. Major tasks in this automatic process includes:

(1) Pipe Stress Analysis

(2) Pipe Support Location Optimization

(3) Stress Isometric Drawing Generation

(4) Pipe Support Pattern Selection and Member Design

(5) 3D Interference Detection for Support

At the core of the System is the AUTO-PIPE (Relational) Database which contains all static (project-specific) and dynamic (model-specific) data required for all of the major tasks listed above.

The AUTO-PIPE CAE System has been used, and is currently being used, for pipe system design for Nuclear Power Plants in Japan to achieve substantial manpower reduction and cost savings.
Computer Assisted Design of Rubber Mounting Springs
Authors: Shoup T. E. , Sanchez L. A.
Published: March 2021

While analysis procedures for the design of rubber mountings have existed for a number of years, the nonlinearity of these useful devices has limited the number of design procedures that are available. This paper presents a design procedure for the static deflections of rubber mountings. It is believed that this is the first time that such numerical procedures have been described in the design literature. The procedures are made possible by a combination of numerical approximations of data in the engineering literature and numerical methods for handling transcendental relationships. Such design procedures would clearly not be possible without the use of the digital computers and the numerical techniques that it facilitates. Design examples are presented to illustrate the use of the numerical procedure.
Mechatronics at Rensselaer: Integration Through Design
Authors: Craig Kevin
Published: March 2021

Mechatronics is the synergistic combination of precision mechanical engineering, electronics, control engineering, and computer science in the design process. This paper describes a new elective course entitled Mechatronics which has been developed and was taught for the first time at Rensselaer during the fall 1991 semester to 45 senior-undergraduate and graduate students. The key areas of mechatronics which are studied in depth in this course are: control sensors and actuators, interfacing sensors and actuators to a microcomputer, discrete controller design, and real-time programming for control using the C programming language. The course is heavily laboratory-based with a two-hour laboratory weekly in addition to three hours of classroom lecture. The laboratory exercises include computer-aided control system design using MATRIXx, various analog and digital sensors, hydraulic actuators, DC and stepper motors, and computer control of a variety of physical systems. The unifying theme for the course is the integration of these key areas into a successful mechatronic design. Students are required, as a final project, to: identify a problem or need, analyze the problem, and write a problem statement; perform a state-of-the-art review; develop a list of specifications and identify the key specifications; generate an outstanding mechatronic-system conceptual design; and finally perform a detailed design of the system which may include model building and hardware development. Examples of student projects are described. This course should significantly enhance our design education program in the Mechanical Engineering Department and lay the foundation for the students to become mechatronic design engineers.
An Interactive, Menu-Driven, Software for Flexural Analysis of Transversely Loaded Beams
Authors: Pao Y. C. , Yur Winston
Published: March 2021

A set of computer programs written in QuickBASIC language has been developed as an instructional aid for the Mechanics of Materials course. It consists of 9 programs and over 50 supporting subprograms. Starting with the span and loading inputs, this software computes the support reactions and displays the diagrams of distributed loads, shearing force, bending moments, slope, and deflection distributions. Disk files are created to save the input and computed data and also the resulting displays for quick retrieval during any phase of the flexural analysis. Various shapes of cursors are created on screen for the user to select any menu involved in the analysis and/or a desired section of the beam for computation of the principal and maximum shearing stresses, for which Mohr’s circle display is also an optional feature. All operations are interactive and menu-driven, and provided with many helpful prompting messages to assist the user to specify the next request.
Development of an Interactive Teaching Tool: Course Designer
Authors: Kilkiş Birol , Kaftanoğlu Bilgin , Güngör Cengiz
Published: March 2021

An expert authoring package for real time, computer aided lecturing was developed with main emphasis to undergraduate courses in mechanical engineering. It enables the instructor to prepare the lecture and then present it in the classroom in a real-time and iterative environment. The major aim is to create a medium in which the instructor, computer and students are brought together on a common data base with real-time interaction with each other. The hardware necessary to enable such an interaction was investigated and optimum configuration laid out both from economical and technical points of view. The package is also flexible enough to permit the instructor to modify and set the topics during the course through a specially designed menu. The Course Designer program which was developed on SuperEdit™ software which enables to structure the course material to be structured using traditional Macintosh building blocks like windows and graphics with a better user friendly and interactive medium.
Computer Representation of the Machining Environment
Authors: Zhang J. , de Sam Lazaro A. , Kendall L. A.
Published: March 2021

Machining is an operation which utilizes both deterministic and heuristic inputs. Quantitative and qualitative judgments are made in order to optimize the process. Geometry, tool path control and so on are generally pre-defined whereas machining parameters such as cutting speed, feed rate and depth of cut require both mathematical and intuitive analyses to produce the best results. Computer representation of the machining environment requires both mathematical and heuristic models. A hybrid model for machining is presented and discussed. The model is simulated experimentally in an intelligent supervisory control system for CNC tape tuning.
Derivation of the Explicit Solution of the Inverse Involute Function and its Applications
Authors: Cheng Harry Hui
Published: March 2021

The involute function ε = tanϕ – ϕ or ε = invϕ, and the inverse involute function ϕ = inv−1(ε) arise in the tooth geometry calculations of involute gears, involute splines, and involute serrations. In this paper, the explicit series solutions of the inverse involute function are derived by perturbation techniques in the ranges of |ε| < 1.8, 1.8 < |ε| < 5, and |ε| > 5. These explicit solutions are compared with the exact solutions, and the expressions for estimated errors are also developed. Of particular interest in the applications are the simple expansion ϕ = inv−1(ε) = (3ε)1/3 – 2ε/5 which gives the angle ϕ (< 45°) with error less than 1.0% in the range of ε < 0.215, and the economized asymptotic series expansion ϕ = inv−1 (ε) = 1.440859ε1/3 – 0.3660584ε which gives ϕ with error less than 0.17% in the range of ε < 0.215. The four, seven, and nine term series solutions of ϕ = inv−1 (ε) are shown to have error less than 0.0018%, 4.89 * 10−6%, and 2.01 * 10−7% in the range of ε < 0.215, respectively. The computation of the series solution of the inverse involute function can be easily performed by using a pocket calculator, which should lead to its practical applications in the design and analysis of involute gears, splines, and serrations.
Kinematical Optimization of Spiral Bevel Gears
Authors: Fong Zhang-Hua , Tsay Chung-Biau
Published: March 2021

Kinematical optimization and sensitivity analysis of circular-cut spiral bevel gears are investigated in this paper. Based on the Gleason spiral bevel gear generator and EPG test machine, a mathematical model is proposed to simulate the tooth contact conditions of the spiral bevel gear set. All the machine settings and assembly data are simulated by simplified parameters. The tooth contact patterns and kinematic errors are obtained by the proposed mathematical model and the tooth contact analysis techniques. Loaded tooth contact patterns are obtained by the differential geometry and the Hertz contact formulas. Tooth surface sensitivity due to the variation of machine settings is studied. The corrective machine settings can be calculated by the sensitive matrix and the linear regression method. An optimization algorithm is also developed to minimize the kinematic errors and the discontinuity of tooth meshing. According to the proposed studies, an improved procedure for development of spiral bevel gears is suggested. The results of this paper can be applied to determine the sensitivity and precision requirements in manufacturing, and improve the running quality of the spiral bevel gears. Two examples are presented to demonstrate the applications of the optimization model.
Application of Face-Gear Drives in Helicopter Transmissions
Authors: Litvin F. L. , Wang J.-C. , Bossler R. B. , Chen Y.-J. D. , Heath G. , Lewicki David G.
Published: March 2021

The use of face gears in helicopter transmissions was explored. A light-weight, split torque transmission design utilizing face gears was described. Face-gear design and geometry were investigated. Topics included tooth generation, limiting inner and outer radii, tooth contact analysis, contact ratio, gear eccentricity, and structural stiffness. Design charts were developed to determine minimum and maximum face-gear inner and outer radii. Analytical study of transmission error showed face-gear drives were relatively insensitive to gear misalignment, but tooth contact was affected by misalignment. A method of localizing bearing contact to compensate for misalignment was explored. The proper choice of shaft support stiffness enabled good load sharing in the split torque transmission design. Face-gear experimental studies were also included and the feasibility of face gears in high-speed, high-load applications such as helicopter transmissions was demonstrated.
Experimental Investigation of Equilibrium Loads in a Planetary Reducer by Oil Film Calculations
Authors: Weiqiang Liu
Published: March 2021

In this paper, some properties of equilibrating load mechanism by oil film are analysed. Loads on the three planet gears are measured by telemeter at the same time. The load distribution laws among planet gears are given under the different torque and rotation rate. A good function of equilibrating load, along the tooth width, is found in testing model machine.
Optimal Design of Compact Spur Gear Reductions
Authors: Savage M. , Lattime S. B. , Kimmel J. A. , Coe H. H.
Published: March 2021

The optimal design of compact spur gear reductions includes the selection of bearing and shaft proportions in addition to the gear mesh parameters. Designs for single mesh spur gear reductions are based on optimization of system life, system volume, and system weight including gears, support shafts, and the four bearings. The overall optimization allows component properties to interact, yielding the best composite design. A modified feasible directions search algorithm directs the optimization through a continuous design space. Interpolated polynomials expand the discrete bearing properties and proportions into continuous variables for optimization. After finding the continuous optimum, the designer can analyze near optimal designs for comparison and selection. Design examples show the influence of the bearings on the optimal configurations.
Effect of Cutter Performance on Finished Tooth Form in Gear Shaving
Authors: Moriwaki I. , Fujita M.
Published: March 2021

The authors have been developed a computer simulation program of gear shaving. In the present paper, a new cutting model of shaving process is proposed so as to incorporate an effect of a cutting performance of shaving cutter into the simulation program. In this cutting model, it is assumed that a tooth flank material of work gear can be removed only when a depth of cut of a cutting edge exceeds a certain criterion. It is also assumed that the criterion have no definite value but has the nominal distribution over the tooth surface. The mean value of the distribution can define a characteristic of cutting performance of shaving cutter. The small mean value means that even small depth of cut can cause a stock removal; i.e. a good cutter performance. The computer simulations on gear shaving are performed to reveal the effect of the cutter performance on shaved tooth form. Under the conditions used in these simulations, the pressure angle error on the shaved tooth profile becomes remarkable as the cutter performance becomes worse. Thus, the developed computer simulation program of gear shaving has a reliability on the prediction of shaved tooth form. It will be useful for design of shaving cutter, judgement of tool life, and so on.
A Comparison Between Theoretical Prediction and Experimental Measurement of the Dynamic Behavior of Spur Gears
Authors: Rebbechi Brian , Forrester B. David , Oswald Fred B. , Townsend Dennis P.
Published: March 2021

A comparison was made between computer model predictions of gear dynamic behaviour and experimental results. The experimental data were derived from the NASA gear noise rig, which was used to record dynamic tooth loads and vibration. The experimental results were compared with predictions from the Australian Defence Science and Technology Organisation Aeronautical Research Laboratory’s gear dynamics code, for a matrix of 28 load-speed points. At high torque the peak dynamic load predictions agree with experimental results with an average error of 5 percent in the speed range 800 to 6000 rpm. Tooth separation (or bounce), which was observed in the experimental data for light-torque, high-speed conditions, was simulated by the computer model. The model was also successful in simulating the degree of load sharing between gear teeth in the multiple-tooth-contact region.