bluuebunny/crossref_metadata_2025 huggingface dataset:
Prevention and Treatment of Postoperative Pain after Lumbar Spine Procedures: A Systematic Review
Authors: Terracina Sergio , Robba Chiara , Prete Anna , Sergi Paola G. , Bilotta Federico
Published: February 2018

Background and Objective

In the past 2 decades, in developed countries, spine procedures (surgical and percutaneous) had the highest absolute increase in case volume trend. The optimal approach to prevent and treat postoperative pain is continuously evolving. This systematic literature review presents evidence on safety and efficacy of pharmacological and nonpharmacological therapies to prevent and treat postoperative pain after lumbar spine procedures.

Databases and Data Treatment

Publications listed in PUBMED and EMBASE were considered to identify randomized clinical trials suitable for inclusion in this systematic review. Key words for literature search were selected, with authors’ agreement, using the PICOS approach (participants, interventions, comparisons, outcomes, and study design).

Results

Fifty‐nine randomized clinical trials (involving a total of 4,238 patients, with ages ranging from 18 to 86 years) published between January 2012 and September 2017 were retrieved. Data are presented according to the timing of therapy administration.

Conclusion and Recommendations

Clinical evidence on perioperative pain management in patients undergoing spine procedures have significantly evolved after the review published in 2012. The aim of this systematic review was to report the latest evidence published. These include the preoperative use of dexamethasone, which was shown to be able to reduce pain at mobilization but not to reduce pain at rest or total morphine consumption; the use of gabapentinoids as part of a multimodal analgesic approach; and the safety and effectiveness of the intraoperative use of ketamine, dexketoprofen, and tramadol. Finally, electrical nerve stimulation is gaining interest and is potentially suitable for clinical needs.
Impact of center volume and the adoption of laparoscopic donor nephrectomy on outcomes in pediatric kidney transplantation
Authors: Burg Jennifer M. , Scott David L. , Roayaie Kayvan , Maynard Erin , Barry John M. , Enestvedt C. Kristian
Published: February 2018

Reports for pediatric kidney transplant recipients suggested better outcomes for ODN compared to LDN. Contemporary outcomes stratified by donor type and center volume have not been evaluated in a national dataset. UNOS data (2000‐2014) were analyzed for pediatric living donor kidney transplant recipients. The primary outcome was GF; secondary outcomes were DGF, rejection, and patient survival. Live donor nephrectomies for pediatric recipients decreased 30% and transitioned from ODN to LDN. GF rates did not differ for ODN vs LDN (P = .24). GF was lowest at high volume centers (P < .01). Donor operative approach did not contribute to GF. LDN was associated with less rejection than ODN (OR 0.66, CI 0.5‐0.87, P < .01). Analysis of the 0‐ to 5‐yr recipient group showed no effect of ODN vs LDN on GF or rejection. For the contemporary era, there was no association between DGF and LDN in the 0‐ to 5‐yr group (OR 1.12, CI 0.67‐1.89, P = .67). Outcomes of kidney transplants in pediatric recipients following LDN have improved since its introduction and LDN should be the approach for live donor nephrectomy regardless of recipient age. The association between case volume and improved outcomes highlights future challenges in organ transplantation.
A New Kind of Nursing: Walking the labyrinth of Cook County Jail
Authors: Gorman Geraldine
Published: February 2018

This paper examines the application of public health nursing education with an emphasis on the social determinants of health within a correctional facility. The innate tension between public health practice and the punitive nature of correctional confinement is discussed through the perspective of student involvement. Exemplars of unexpected contingencies endemic to this practice setting are provided as are insights gleaned from this pilot collaboration between a college of nursing and a county correctional system.
Mitosis count and number of cancer cells in cases of primary pulmonary adenocarcinoma: Correlations among phosphorylated histone 3, number of cancer cells, nuclear grade, pathologic features and prognosis
Authors: Inoue Takashi , Nakazato Yoshimasa , Karube Yoko , Maeda Sumiko , Kobayashi Satoru , Chida Masayuki
Published: February 2018

Immunohistochemistry findings for the phosphorylated form of histone 3 (pHH3) have been shown to be a reliable mitosis‐specific marker. We evaluated the correlation between pHH3‐stained mitotic figures (PHMFs) and clinical outcome, and compared the results with findings for numbers of PHMFs and cancer cells. The primary tumor was obtained from 113 patients with pulmonary adenocarcinomas (≤2 cm maximum dimension). All specimens were stained with pHH3, then the number of cancer cells in each was determined. Cases with a cancer‐cell index ≥1000 showed worse recurrence‐free survival as compared to those with a value <1000 (P < 0.001). Also, cases with a pHH3 index ≥0.27 showed worse recurrence‐free survival as compared to <0.27 (P = 0.001) and cases with a pHH3/cancer‐cell index ≥0.001 showed worse recurrence‐free survival as compared to <0.001 (P = 0.002). Multivariate analysis demonstrated that pHH3/cancer‐cell index was significantly correlated with prognosis, but not Ki‐67 index. The number of cancer cells was also strongly correlated with progression of Noguchi's classification and WHO pathologic type. pHH3/cancer‐cell index was correlated with prognosis, and those were useful for prognostic evaluation of pulmonary adenocarcinoma patients. Furthermore, cancer cell number was correlated with Noguchi's classification and WHO pathologic type.
Insights into intraspecific wood density variation and its relationship to growth, height and elevation in a treeline species
Authors: Fajardo A.
Published: February 2018

The wood economics spectrum provides a general framework for interspecific trait–trait coordination across wide environmental gradients. Whether global patterns are mirrored within species constitutes a poorly explored subject. In this study, I first determined whether wood density co‐varies together with elevation, tree growth and height at the within‐species level. Second, I determined the variation of wood density in different stem parts (trunk, branch and twigs).

In situtrunk sapwood, trunk heartwood, branch and twig densities, in addition to stem growth rates and tree height were determined in adult trees ofNothofagus pumilioat four elevations in five locations spanning 18° of latitude. Mixed effects models were fitted to test relationships among variables.

The variation in wood density reported in this study was narrow (ca. 0.4–0.6 g cm−3) relative to global density variation (ca. 0.3–1.0 g cm−3). There was no significant relationship between stem growth rates and wood density. Furthermore, the elevation gradient did not alter the wood density of any stem part. Trunk sapwood density was negatively related to tree height. Twig density was higher than branch and trunk densities. Trunk heartwood density was always significantly higher than sapwood density.

Negative across‐species trends found in the growth–wood density relationship may not emerge as the aggregate of parallel intraspecific patterns. Actually, trees with contrasting growth rates show similar wood density values. Tree height, which is tightly related to elevation, showed a negative relationship with sapwood density.
Understanding Fear of Zika: Personal, Interpersonal, and Media Influences
Authors: Yang Chun , Dillard James Price , Li Ruobing
Published: February 2018

Fear of infectious disease often motivates people to protect themselves. But, it can also produce negative bio‐social‐psychological effects whose severity is on par with those of the disease. The WHO declaration of Zika as a world health crisis presented an opportunity to study factors that bring about fear. Beginning nine days after the WHO announcement, data were gathered from women aged 18–35 living in the southern United States (N= 719). Respondents reported experiencing fear of Zika at levels akin to those reported following other significant crises/disasters (e.g., the terrorist attacks of 9/11). Fear increased as a function of (1) personal, but not other‐relevance, (2) frequency of media exposure, but not media content, and (3) frequency of interpersonal exposure and interpersonal content. It is argued that media and interpersonal message sources may be innately predisposed to amplify, rather than attenuate, risk.
Eccentric exercise induces spatial changes in the mechanomyographic activity of the upper trapezius muscle
Authors: Madeleine P. , Hansen E. A. , Andersen R. E. , Kumorek M. , Mroczek D. , Samani A. , Kawczyński A.
Published: February 2018

In this study, we hypothesized that the recordings of multichannel mechanomyography (MMG) of the upper trapezius muscle would reveal spatially dependent manifestations in the presence of delayed onset muscle soreness occurring 24 hours after eccentric exercise (ECC). Sixteen participants performed high‐intensity eccentric exercises (5 sets of 10 eccentric contractions at 100% of max elevation force) targeting the upper trapezius on their dominant side. Twelve accelerometers were attached to record MMG activity during submaximal exercise consisting of static and dynamic arm flexion and abduction. Measurements were taken before and 24 hours after ECC. Average rectified value (ARV), percentage of determinism (% DET), and recurrence (% REC) of the MMG signals were computed to estimate the level of muscular activity and the magnitude of regularity of the MMG. The ARV, % REC, and % DET maps revealed heterogeneous MMG activity of the upper trapezius 24 hours after ECC when compared with before. Increased ARV, % REC, and % DET were found 24 hours after ECC when compared with before. The study provides new key information on how a single muscle responds to ECC. Our findings suggest that multichannel MMG and nonlinear analyses may detect muscular and musculo‐tendinous alterations due to ECC.
Soil property differences among high‐ and average‐yielding soya bean areas in Arkansas, USA
Authors: Adams T. C. , Brye K. R. , Purcell L. C. , Ross W. J. , Gbur E. E. , Savin M. C.
Published: February 2018

Soya bean [Glycine max (L.) Merr] yields >6719 kg/ha (100 bu/ac) have only recently and infrequently been achieved. Quantifying soil property differences between high‐ and average‐yielding areas can help to further identify non‐plant‐related properties contributing to soya bean yield potential. The objective of this study was to evaluate the effects of region and soil depth on soil property differences between high‐ and average‐yielding areas. In each of the seven regions of the ‘Grow for the Green’ yield contest in Arkansas, prior to or just after harvest in 2014 and 2015, soil samples were collected from the top 20 cm of one contest high‐yield (HY) area that was in close proximity to an average‐yield (AY) area. Across all regions and both years, soya bean yields differed (P < 0.05) between yield areas, averaging 4701 and 5498 kg/ha in AY and HY areas, respectively. Averaged across soil depth and years, numerous soil properties differed (P < 0.05) between HY and AY areas within at least one of seven regions. Total soil C content was at least 20.2% greater in the HY than in the AY area in three of seven regions. Extractable soil P content was, on average, 19.4 kg/ha greater in HY than in AY areas in three of the seven regions. Results from this study have the potential to help producers better understand soil properties that contribute to or hinder achieving ultra‐high (>6719 kg/ha) soya bean yields.
Identification of the novel HLA‐C*03 allele, HLA‐C*03:03:35
Authors: Park B. G. , Oh H.‐B. , Im J. , Yoon C. E. , Kwon O.‐J.
Published: February 2018

The new allele HLA‐C*03:03:35 showed one nucleotide difference with C*03:03:01:01 at position 408 (G>T).
Management of injured patients who were Jehovah's Witnesses, where blood transfusion may not be an option: a retrospective review
Authors: Olaussen A. , Bade‐Boon J. , Fitzgerald M. C. , Mitra B.
Published: February 2018

Introduction

Management of major haemorrhage as a result of trauma is particularly challenging when blood is not an option (BNAO). Evidence on therapeutic strategies in this situation is limited. The aim of this study was to evaluate the management and outcomes of patients who identified themselves as Jehovah's Witnesses (who usually refuse blood products) with traumatic haemorrhage at an Australian major trauma centre.

Methods

A retrospective review of patients from The Alfred Trauma Registry was conducted, including patients who were Jehovah's Witnesses presenting between January 2010 and January 2017. We examined demographics, injury characteristics, clinical progress, therapeutic interventions and outcomes at hospital discharge.

Results

There were 34 patients meeting inclusion criteria, with 50% suffering major trauma. Anaemia was a clinical problem for 13 (38·2%) patients, with haemoglobin levels reaching a nadir of 69·7 g/l (95% CI: 56·7–82·7) on average 5·1 days (95% CI: 2·5–7·7) post admission. Various strategies were employed to reduce blood loss including six (46·2%) patients receiving tranexamic acid, nine (29·2%) patients receiving oral or intravenous iron and five (38·5%) receiving erythropoietin. Three patients received packed red cells, and two patients received synthetic haemoglobin‐based oxygen carriers.

Conclusions

Numerous therapeutic strategies were employed inconsistently in this unique population of patients. Augmenting circulatory volume with an oxygen carrier acceptable to JW patients presents a novel approach to be considered in adjunct to other strategies. An international resource centre would assist clinicians faced with anaemia and BNAO.
In search of a meaningful classification for Amazonian marmosets: Should dwarf marmosets be consideredMicocongenerics?
Authors: Silva Felipe E. , Costa‐Araújo Rodrigo , Boubli Jean P. , Santana Marcelo I. , Franco Caetano L. B. , Bertuol Fabrício , Nunes Hermano , de Souza Silva‐Júnior José , Farias Izeni , Hrbek Tomas
Published: February 2018

The criteria to classify the diversity of Neotropical Primates have recently taken the discussion boards due to the reappraisal on the phylogenetic relationship of some groups. Such controversial and arbitrary decisions, however, can hamper conservation actions in as much as it becomes difficult to prioritise and set meaningful targets. It is the case for dwarf marmosets from central Amazonia. Today, the classification of dwarf marmosets inMicoorCallibellagenus has not been satisfactorily settled. Aiming to contribute to the taxonomic and conservation assessment of dwarf marmosets, we conducted new data collection during 3‐year fieldwork in the Aripuanã River, where the species was discovered. We present the first phylogenomic analysis of the evolutionary relationships between marmosets, new data from mitochondrial DNA and morphology, as well new records to clarify geographic distribution. With this new evidence, we support dwarf marmosets as the genusCallibella. We further discuss the implications for the conservation of this marmoset.
Roots of Violence by ISIS, An Analysis on Beliefs
Authors: Bozorgmehri Majid
Published: February 2018

ISIS was an Islamic fundamentalist organization which presents a radical version of Islamic beliefs, encourages holy violence, and considers others who do not agree with its understandings as apostates.As a theoretical debate, the discussions developed by Gregg could cover the arguments stated through this study. He considers Social Movements, Fundamentalists, and Cosmic Warriors as the frameworks of religious cruelty.Daesh`s Dogma could be analyzed in two levels: traditional platform and new generation literature. As the former, three pillars Salafism. Qutbism and Wahhabism shape the basements and frameworks of IS`s ideological structure. New generation literature, joined with an anti-western attitude and combined also with a Sense of revenge against the old powers of imperialism, justify the most violent acts everywhere.As an alternative of being shaped in traditional dogma, ISIS’s philosophy could be drawn from 3 new booklets. The Management of Savagery (Idarat al-tawahhush) written in 2000s by Abu Bakr al-Naji, is one of them.For methodological aspect, the content analysis, concentrated on the basic sources is selected and for discussing the arguments, a descriptive analytical method is opted.
Efficiency of Pollution Tolerance Index (PTI) of macroinvertebrates in detecting aquatic pollution in an oxbow lake in India
Authors: Ghosh Dipankar , Biswas Jayanta Kumar
Published: February 2018

This paper evaluates the efficiency of a macroinvertebrate-based Pollution Tolerance Index (PTI) in detecting aquatic pollution in the Chhariganga oxbow lake in India. In this lake, calculated PTIs were compared with results from an array of physicochemical water and sediment parameters and to a macroinvertebrate diversity assessment conducted in parallel for the same lake. The obtained PTI values fell in a range (between 20 and 31) that are indicative of an absence of organic pollution according to the literature, and are normally reported for systems devoid of anthropogenic activity (for instance no monsoonal polluting jute retting activities). However, in the light of the results for the assessed water and sediment physicochemical parameters, and the support of diversity indexes of macroinvertebrates, using data from the same lake, it was possible to conclude that the obtained PTI values do not reflect the true pollution status of this oxbow lake. As PTI values and diversity indexes contradict each other in detecting pollution, it is advised to take both parameters into consideration when using macroinvertebrates to assess aquatic health.
Between Open Sets and Semi-Open Sets
Authors: Al Ghour Samer , Mansur Kafa
Published: February 2018

We introduce and investigate ω_s-open sets as a new class of sets which are strictly between open sets and semi-open sets. Then we use ω_s-open sets to introduce ω_s-continuous functions as a new class of functions between continuous functions and semi-continuous functions. We give several results and examples regarding our new concepts. In particular, we obtain some characterizations of ω_s-continuous functions.
A Priori Assessment of Adipose Tissue Mechanical Testing by Global Sensitivity Analysis
Authors: Naseri Hosein , Johansson Håkan
Published: February 2018

In modeling the mechanical behavior of soft tissues, the proper choice of an experiment for identifying material parameters is not an easy task. In this study, a finite element computational framework is used to virtually simulate and assess commonly used experimental setups: rotational rheometer tests, confined- and unconfined-compression tests, and indentation tests. Variance-based global sensitivity analysis is employed to identify which parameters in different experimental setups govern model prediction and are thus more likely to be determined through parameter identification processes. Therefore, a priori assessment of experimental setups provides a base for systematic and reliable parameter identification. It is found that in indentation tests and unconfined-compression tests, incompressibility of soft tissues (adipose tissue in this study) plays an important role at high strain rates. That means bulk stiffness constitutes the main part of the mechanism of tissue response; thus, these experimental setups may not be appropriate for identifying shear stiffness. Also, identified material parameters through loading–unloading shear tests at a certain rate might not be reliable for other rates, since adipose tissue shows highly strain rate dependent behavior. Frequency sweep tests at a wide-enough frequency range seem to be the best setup to capture the strain rate behavior. Moreover, analyzing the sensitivity of model parameters in the different experimental setups provides further insight about the model itself.
Unsteady Pressure Measurement on Oscillating Blade in Transonic Flow Using Fast-Response Pressure-Sensitive Paint
Authors: Watanabe Toshinori , Azuma Toshihiko , Uzawa Seiji , Himeno Takehiro , Inoue Chihiro
Published: February 2018

A fast-response pressure-sensitive paint (PSP) technique was applied to the measurement of unsteady surface pressure of an oscillating cascade blade in a transonic flow. A linear cascade was used, and its central blade was oscillated in a translational manner. The unsteady pressure distributions of the oscillating blade and two stationary neighbors were measured using the fast-response PSP technique, and the unsteady aerodynamic force on the blade was obtained by integrating the data obtained on the pressures. The measurements made with the PSP technique were compared with those obtained by conventional methods for the purpose of validation. From the results, the PSP technique was revealed to be capable of measuring the unsteady surface pressure, which is used for flutter analysis in transonic conditions.
Prediction of the Turbine Tip Convective Heat Flux Using Discrete Green's Functions
Authors: Andreoli Valeria , Cuadrado David G. , Paniagua Guillermo
Published: February 2018

The heat fluxes across the turbine tip gap are characterized by large unsteady pressure gradients and shear from the viscous effects. The classical Newton heat convection equation, based on the turbine inlet total temperature, is inadequate. Previous research from our team relied on the use of the adiabatic wall temperature. In this paper, we propose an alternative approach to predict the convective heat transfer problem across the turbine rotor tip using discrete Green's functions (DGF). The linearity of the energy equation in the solid domain with constant thermal properties can be applied with a superposition technique to measure the data extracted from flow simulations to determine the Green's function distribution. The DGF is a matrix of coefficients that relate the temperature spatial (GF) distribution with the heat flux. This methodology is first applied to a backward facing step, validated using experimental data. The final aim of this paper is to demonstrate the method in the rotor turbine tip. A turbine stage at engine-like conditions was assessed using cfd software. The heat flux pulses were applied at different locations in the rotor tip geometry, and the increment of temperature in this zone was evaluated for different clearances, with a consequent variation of the DGF coefficients. Ultimately, a detailed uncertainty analysis of the methodology was included based on the magnitude of the heat flux pulses used in the DGF coefficients calculation and the uncertainty in the experimental measurements of the wall temperature.
Dynamics and Control of a Novel Active Yaw Stabilizer to Enhance Vehicle Lateral Motion Stability
Authors: Wang Fengchen , Chen Yan
Published: February 2018

In this paper, a novel active yaw stabilizer (AYS) system is proposed for improving vehicle lateral stability control. The introduced AYS, inspired by the recent in-wheel motor (IWM) technology, has two degrees-of-freedom with independent self-rotating and orbiting movements. The dynamic model of the AYS is first developed. The capability of the AYS is then investigated to show its maximum generation of corrective lateral forces and yaw moments, given a limited vehicle space. Utilizing the high-level Lyapunov-based control design and the low-level control allocation design, a hierarchical control architecture is established to integrate the AYS control with active front steering (AFS) and direct yaw moment control (DYC). To demonstrate the advantages of the AYS, generating corrective lateral force and yaw moment without relying on tire–road interaction, double lane change maneuvers are studied on road with various tire–road friction coefficients. Co-simulation results, integrating CarSim® and MATLAB/Simulink®, successfully verify that the vehicle with the assistance of the AYS system has better lateral dynamics stabilizing performance, compared with cases in which only AFS or DYC is applied.
A Novel Adaptive Active Control Projective Synchronization of Chaotic Systems
Authors: Quan Boan , Wang Chunhua , Sun Jingru , Zhao Yilin
Published: February 2018

This paper investigates adaptive active control projective synchronization scheme. A general synchronization controller and parameter update laws are proposed to stabilize the error system for the identical structural chaotic systems. It is the first time that the active synchronization, the projective synchronization, and the adaptive synchronization are combined to achieve the synchronization of chaotic systems, which extend the control capability of achieving chaotic synchronization. By using a constant diagonal matrix, the active control is developed. Especially, when designing the controller, we just need to ensure that the diagonal elements of the diagonal matrix are less than or equal 0. So, the synchronization of chaotic systems can be realized more easily. Furthermore, by proposing an active controller, in combination with several different control schemes, we lower the complexity of the design process of the controller. More importantly, the larger the absolute value of product of the diagonal elements of diagonal matrix is, the smoother the curve of chaotic synchronization is and the shorter the time of chaotic synchronization is. In our paper, we take Lorenz system as an example to verify the effectiveness of the proposed synchronization scheme. Theoretical analysis and numerical simulations demonstrate the feasibility of this control method.
A Semi-Analytical Method for Calculation of Strongly Nonlinear Normal Modes of Mechanical Systems
Authors: Mahmoudkhani S.
Published: February 2018

A new scheme based on the homotopy analysis method (HAM) is developed for calculating the nonlinear normal modes (NNMs) of multi degrees-of-freedom (MDOF) oscillatory systems with quadratic and cubic nonlinearities. The NNMs in the presence of internal resonances can also be computed by the proposed method. The method starts by approximating the solution at the zeroth-order, using some few harmonics, and proceeds to higher orders to improve the approximation by automatically including higher harmonics. The capabilities and limitations of the method are thoroughly investigated by applying them to three nonlinear systems with different nonlinear behaviors. These include a two degrees-of-freedom (2DOF) system with cubic nonlinearities and one-to-three internal resonance that occurs on nonlinear frequencies at high amplitudes, a 2DOF system with quadratic and cubic nonlinearities having one-to-two internal resonance, and the discretized equations of motion of a cylindrical shell. The later one has internal resonance of one-to-one. Moreover, it has the symmetry property and its DOFs may oscillate with phase difference of 90 deg, leading to the traveling wave mode. In most cases, the estimated backbone curves are compared by the numerical solutions obtained by continuation of periodic orbits. The method is found to be accurate for reasonably high amplitude vibration especially when only cubic nonlinearities are present.
First Principle Based Control Oriented Gasoline Engine Model Including Lumped Cylinder Dynamics
Authors: Yar Ahmed , Bhatti A. I. , Ahmed Qadeer
Published: February 2018

A novel first principle based control oriented model of a gasoline engine is proposed which also carries diagnostic capabilities. Unlike existing control oriented models, the formulated model reflects dynamics of the faultless as well as faulty engine with high fidelity. In the proposed model, the torque production subsystem is obtained by integration of further two subsystems that is model of a single cylinder torque producing mechanism and an analytical gasoline engine cylinder pressure model. Model of a single cylinder torque producing mechanism is derived using constrained equation of motion (EOM) in Lagrangian mechanics. While cylinder pressure is evaluated using a closed form parametric analytical gasoline engine cylinder pressure model. Novel attributes of the proposed model include minimal usage of empirical relations and relatively wider region of model validity. Additionally, the model provides model based description of crankshaft angular speed fluctuations and tension in the rigid bodies. Capacity of the model to describe the system dynamics under fault conditions is elaborated with case study of an intermittent misfire condition. Model attains new capabilities based on the said novel attributes. The model is successfully validated against experimental data.
Variable Damping Profiles Using Modal Analysis for Laser Shock Peening Simulation
Authors: Hatamleh Mohammad I. , Mahadevan Jagannathan , Malik Arif , Qian Dong
Published: February 2018

The single explicit analysis using time-dependent damping (SEATD) technique for laser shock peening (LSP) simulation employs variable damping to relax the excited model between laser shots, thus distinguishing it from conventional optimum constant damping methods. Dynamic relaxation (DR) is the well-established conventional technique that mathematically identifies the optimum constant damping coefficient and incremental time-step that guarantees stability and convergence while damping all mode shapes uniformly when bringing a model to quasi-static equilibrium. Examined in this research is a new systematic procedure to strive for a more effective, time-dependent variable damping profile for general LSP configurations and boundary conditions, based on excited modal parameters of a given laser-shocked system. The effects of increasing the number of mode shapes and selecting modes by contributed effective masses are studied, and a procedure to identify the most efficient variable damping profile is designed. Two different simulation cases are studied. It is found that the computational time is reduced by up to 25% (62.5 min) for just five laser shots using the presented variable damping method versus conventional optimum constant damping. Since LSP typically involved hundreds of shots, the accumulated savings in computation time during prediction of desired process parameters is significant.
Additive Manufacturing Constraints in Topology Optimization for Improved Manufacturability
Authors: Mhapsekar Kunal , McConaha Matthew , Anand Sam
Published: February 2018

Additive manufacturing (AM) provides tremendous advantage over conventional manufacturing processes in terms of creative freedom, and topology optimization (TO) can be deemed as a potential design approach to exploit this creative freedom. To integrate these technologies and to create topology optimized designs that can be easily manufactured using AM, manufacturing constraints need to be introduced within the TO process. In this research, two different approaches are proposed to integrate the constraints within the algorithm of density-based TO. Two AM constraints are developed to demonstrate these two approaches. These constraints address the minimization of number of thin features as well as minimization of volume of support structures in the optimized parts, which have been previously identified as potential concerns associated with AM processes such as powder bed fusion AM. Both the manufacturing constraints are validated with two case studies each, along with experimental validation. Another case study is presented, which shows the combined effect of the two constraints on the topology optimized part. Two metrics of manufacturability are also presented, which have been used to compare the design outputs of conventional and constrained TO.
A Knowledge Management System to Support Design for Additive Manufacturing Using Bayesian Networks
Authors: Wang Yuanbin , Blache Robert , Zheng Pai , Xu Xun
Published: February 2018

Design for additive manufacturing (DfAM) is gaining increasing attention because of the unique capabilities that additive manufacturing (AM) technologies provide. While they have the ability to produce more complex shapes at no additional cost, AM technologies introduce new constraints. A detailed knowledge of the AM process plays an important role in the design of parts in order to achieve the desired print result. However, research on knowledge management in this area is still limited. The large number of different AM processes, their individual sets of critical parameters and the variation in printing all contribute to a high level of uncertainty in this knowledge domain. Applying AM at the early stages of design projects introduces another source of uncertainty, as requirements are often not well defined at that point. In this paper, a knowledge management system using Bayesian networks (BNs) is proposed to model AM knowledge in cases where there is some uncertainty and fill the knowledge gap between designers and AM technologies. The structure of the proposed model is defined here by introducing the overview layer and detailed information layer. In each layer, different types of nodes and their causal relationships are defined. The system can learn conditional probabilities in the model from different sources of information and inferences can be conducted in both forward and backward directions. To verify the accuracy of the BNs, a sample model for dimensional accuracy in the fused deposition modeling (FDM) process is presented and the results are compared with other methods. A case study is provided to illustrate how the proposed system can help designers with different design questions understand the capabilities of AM processes and find appropriate design and printing solutions.
The Torque Capacity of a Magnetorheological Fluid Brake Compared to a Frictional Disk Brake
Authors: Waheed Salwan O. , Manring Noah D.
Published: February 2018

In this technical brief, the authors compare the torque capacity of a magnetorheological (MR) fluid brake with a conventional frictional disk brake. In the development of the torque models for both brakes, a mathematical expression for the compared torque ratio is presented. For the frictional disk brake, constant pressure and constant wear theories are considered, while static torque of the MR fluid brake is considered for comparison purpose only. Throughout the analysis, the outer radius of the compared brakes is assumed to be the same to ensure similarity of size, while the inner radius is selected to achieve maximum values of braking torque for both brake designs. Reasonable values of design variables for each brake are obtained from references and adopted in this study for making comparisons between the two designs. In conclusion, it is shown that the torque capacity for a frictional disk brake is 10–18 times greater than the torque capacity for a MR fluid brake of similar size.
A Review of Theoretical and Experimental Research on Various Autofrettage Processes
Authors: Shufen Rajkumar , Dixit Uday S.
Published: February 2018

Autofrettage is a metal forming technique widely incorporated for strengthening the thick-walled cylindrical and spherical pressure vessels. The technique is based on the principle of initially subjecting the cylindrical or spherical vessel to partial plastic deformation and then unloading it; as a result of which compressive residual stresses are set up. On the basis of the type of the forming load, autofrettage can be classified into hydraulic, swage, explosive, thermal, and rotational. Considerable research studies have been carried out on autofrettage with a variety of theoretical models and experimental methods. This paper presents an extensive review of various types of autofrettage processes. A wide range of theoretical models and experimental studies are described. Optimization of an autofrettage process is also discussed. Based on the review, some challenging issues and key areas for future research are identified.
The Effect of the Sample Line Length on Gas Turbine Emissions Measurement
Authors: Gill Thomas James , Zheng Lukai , Ubogu Emamode A. , Ahmed Ihab , Khandelwal Bhupendra
Published: February 2018

It is a well-known fact that NO2 has far more harmful effects as compared to NO. NO2 creates ozone, which causes eye irritation and exacerbates respiratory conditions. This leads to an increased emergency departments’ visits and hospital admissions for respiratory issues, especially asthma. Under current situation, majority of regulations deal with total NOx emissions, without looking at the break-up of NO2 and NO. However, there is a feeling in emissions regulation community to implement regulations on NO2 emissions. There are standards to measure total NOx emissions. However, these standards are not equipped enough to measure NO2 emissions accurately. The effect of sample line length on NO2 emissions is not fully understood to date. Also, the standards only suggests maximum of 10 seconds residence time regardless of what the line length is. In this study, a systematic experimental test campaign has been conducted to understand the effect of sample line length on NO2, NO distribution. The residence time was maintained below 10 seconds in accordance with the SAE ARP1256D standards. A Rolls-Royce gas turbine combustor and different calibration cylinders have been used to study the effect of sample line length. A numerical study has also been done to predict the conversion of NO2 to NO. It has been found that with increasing sample line length, more NO2 gets converted to NO and overall NO2 emissions show a reduction, whereas this would not be the case at engine exhaust. This effect of sample line length can be used as a loophole in giving lower NO2 emissions readings.
An Experimental Investigation on Hysteresis in a Wet Gas Compressor
Authors: Bakken Martin , Bjørge Tor
Published: February 2018

Performance monitoring of wet gas compressors is challenging due to the liquid phase impact on performance. Introduction of a liquid phase alters both the thermodynamics as well as the fluid dynamics of the compression process. Hence, understanding the flow interaction between the impeller, diffuser and volute is pivotal. Previous investigations have detected occurrence of compressor hysteresis at certain wet gas operating conditions, resulting in temporary deviations from the steady state compressor characteristics. This kind of behavior influences both the compressor stability and performance. Thus, being able to understand the onset of hysteresis and its impact on the compressor is paramount.

An experimental test campaign has been performed at the Norwegian University of Science and Technology (NTNU). The test facility is an open loop configuration consisting of a shrouded centrifugal impeller, a vaneless diffuser and a circular volute. The current investigation document the compressor performance shift and the occurrence of compressor hysteresis when gradually increasing the liquid load on a centrifugal compressor. Emphasis was put on the compressor performance and its correlation to the diffuser multiphase flow regime. The investigation revealed that there is a clear dependence between the diffuser multiphase flow characteristics and the compressor performance.
Volute Flow Influence on Wet Gas Compressor Performance
Authors: Bakken Martin , Bjørge Tor
Published: February 2018

The world’s energy demand is increasing, asking for new and cost-efficient ways to extract oil and gas. With traditional technologies, oil and gas production relies on a sufficiently high well head pressure for transportation to nearby process facilities. Utilization of subsea wet gas compression systems enables production at significantly lower pressures and is a favourable solution concerning production in remote regions.

Wet gas compressors are particularly useful when handling multiphase mixtures consisting of 95%–100% gas, on a volumetric basis. The remaining content is water and liquid condensate, which introduces flow mechanisms such as droplet deposition, liquid film formation and momentum transfer, which influence the fundamental flow behavior through the compressor. Previous tests have documented the occurrence of compressor hysteresis at low compressor flow rates. Recent findings have revealed the flow interaction between the diffuser and the volute is a governing factor concerning the documented hysteresis. This kind of behaviour induces challenges with regard to compressor performance prediction and securing stable operation.

An experimental test campaign has been performed at the Norwegian University of Science and Technology (NTNU). The test facility is an open loop configuration consisting of a shrouded centrifugal impeller, a vaneless diffuser and a circular volute. The test was performed by establishing the compressor characteristics while monitoring the diffuser/volute flow regime. Emphasis was put on the volute flow characteristics and the correlation with the compressor performance.

The investigation reveals that the volute flow characteristics and the interaction with the diffuser has a distinct impact on the compressor performance, particularly at lower gas mass fractions. Furthermore, the test reveals that the diffuser design is a key factor concerning the performance impact.
Finite Element Analysis for Dynamic Response of Rotor-Bearing System With Cracked Functionally Graded Turbine Shaft
Authors: Gayen Debabrata , Chakraborty Debabrata , Tiwari Rajiv
Published: February 2018

This paper describes finite element (FE) analysis of a rotor-bearing system having a functionally graded (FG) shaft with a transverse breathing crack. Two nodded Timoshenko beam element with four degrees of freedom (DOFs) per node has been considered and effects of translational and rotary inertia, transverse shear deformations, and gyroscopic moments are also considered. The FG shaft is considered to be composed of zirconia (ZrO2) and stainless steel (SS) with the volume fraction of SS increasing towards the inner radius of the shaft. Thermo-elastic material properties are considered in the radial direction of the FG shaft following power law gradation. Local flexibility coefficients (LFCs) of the cracked FG shaft are determined analytically as a function of crack size, power law gradient index (k), and temperature with crack orientation using the Castigliano’s theorem and Paris’s equations which are used to compute the stiffness matrix in the FE analysis. The FE formulation has been validated with the analytical and FE solutions reported in the literatures, and then natural frequencies and whirling (forward and backward) frequencies are determined. Influences of crack size, power law gradient index, slenderness ratio, and temperature gradient with crack orientation, on the dynamic responses of the rotor-bearing system with an FG shaft are studied. Results show that the power law gradient index has significant influence on the natural frequencies and whirling frequencies for the rotor-bearing system with the breathing cracked FG shaft and the choice of power law index could play an important role in design of FG shafts under thermo-mechanical environment from the view point of damage tolerant design.
Parametric Evaluation on the Response of Damaged Simple Supported Structure Under Transit Mass
Authors: Jena Shakti P. , Parhi Dayal R. , Subbaratnam B.
Published: February 2018

In the present article, the responses of a double cracked simply supported beam have been investigated. The responses of the structure are determined using Duhamel integral method numerically and validated with finite element analysis (FEA) using ANSYS WORKBENCH 2015 along with experimental verifications. The mass is moving on the structure in terms of critical speed of the structure. The normalized deflections of the structure at different damaged configurations are calculated. The influences of speed, mass, crack depth and crack location on the structures response are investigated. It is observed that the results obtained from Duhamel integral converge well with FEA and experimental verifications.
Effect of Pressure Ratio on Bending Mode Flutter in a Transonic Linear Cascade
Authors: Jutur Prahallada , Govardhan Raghuraman N.
Published: February 2018

Vibration related issues such as flutter have always been a cause of concern for aircraft engine designers. They not only incur unwarranted cost and time overruns, but also significantly compromise performance and can cause structural damage. This phenomenon has become more relevant for the modern aircraft engines, which employ relatively thin, long blade rows to satisfy ever growing demand for a powerful yet compact engine. The tip sections of such blade rows operate with supersonic relative velocity, where prediction of flutter can get challenging due to unsteady flow features like oscillating shocks and their interaction with the blade motion. Linear cascades that represent a specific radial location of the rotor have proven to be a reliable tool for flutter studies. To facilitate flutter experiments at flow Mach numbers realistic to the aircraft engine components, a transonic cascade facility operating at a Mach Number (M) of 1.3 with the ability to oscillate the central blade in the cascade has been developed. The cascade consists of 5 blades and two false blades of which the central blade is oscillated in heave, which represents the bending mode of the rotor. The typical reduced frequencies associated with this kind of flutter in practice (k ∼ 0.1) correspond to a high dimensional frequency of 200 Hz for the present case. A barrel cam mechanism is used to provide such high frequency oscillations. The parameters varied in the present study include the reduced frequency (k) and the static pressure ratio (SPR) across the cascade, which is varied with the help of tailboard and flap arrangement located at the back end of the cascade. Three SPR cases of 1.05, 1.25, and 1.35 are considered and at each of these pressure ratio cases, the reduced frequency is varied. The unsteady loads are measured on the oscillating central blade during the oscillation cycle to quantify the energy transfer from flow to blade and shadowgraphy is used to visualize the shocks. The results from these experiments indicate flutter at lower k values for all the SPR cases tested, while the higher k values are damped. The magnitude of excitation or damping at any particular frequency is also observed to increase with increasing SPR.
Experimental Investigation of Perforated Enclosures in Confined Natural Convection
Authors: Bhatia Ribhu , Malhotra Vinayak
Published: February 2018

The work attempts to address excessive heating and related risks in most of the engineering systems. Perforations are well known to boost heat transfer. Present work is an attempt to pact optimization of perforated enclosures for internal natural convection heat transfer. Heat dissipation effect is experimented over a flat plate and implications are understood with variation in convective heat transfer coefficient. Controlling parameters viz., plate orientation, perforation shape and size, enclosures in diverse configurations are varied systematically aiming enhanced heat transfer. Results confirm fact that perforated enclosures significantly affect the heat transportation. Enclosures with varying perforations are found to yield distinct heat sink characteristics. For varying perforation shape, size and plate orientation, the heat transfer rate variation is owed by the resultant flow behavior which governs the energy transference. The complied results are noted as excellent physical insight and optimized to propose a novel design for operations under varying heat transfer requirements for wide-ranging applications.