bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Managers’ Coaching Conversations on Staff Knowledge Use and Performance in Long‐Term Care Settings
Authors: Cummings Greta G. , Hewko Sarah J. , Wang Mengzhe , Wong Carol A. , Laschinger Heather K. Spence , Estabrooks Carole A.
Published: July 2017

Background

Extended lifespans and complex resident care needs have amplified resource demands on nursing homes. Nurse managers play an important role in staff job satisfaction, research use, and resident outcomes. Coaching skills, developed through leadership skill‐building, have been shown to be of value in nursing.

Aims

To test a theoretical model of nursing home staff perceptions of their work context, their managers’ use of coaching conversations, and their use of instrumental, conceptual and persuasive research.

Methods

Using a two‐group crossover design, 33 managers employed in seven Canadian nursing homes were invited to attend a 2‐day coaching development workshop. Survey data were collected from managers and staff at three time points; we analyzed staff data (n = 333), collected after managers had completed the workshop. We used structural equation modeling to test our theoretical model of contextual characteristics as causal variables, managers’ characteristics, and coaching behaviors as mediating variables and staff use of research, job satisfaction, and burnout as outcome variables.

Results

The theoretical model fit the data well (χ2 = 58, df = 43, p = .06) indicating no significant differences between data and model‐implied matrices. Resonant leadership (a relational approach to influencing change) had the strongest significant relationship with manager support, which in turn influenced frequency of coaching conversations. Coaching conversations had a positive, non‐significant relationship with staff persuasive use of research, which in turn significantly increased instrumental research use. Importantly, coaching conversations were significantly, negatively related to job satisfaction.

Linking Evidence to Action

Our findings add to growing research exploring the role of context and leadership in influencing job satisfaction and use of research by healthcare practitioners. One‐on‐one coaching conversations may be difficult for staff not used to participating in such conversations. Resonant leadership, as expected, has a significant impact on manager support and job satisfaction among nursing home staff.
A Comparison of the Incidence of Post‐Dural Puncture Headache and Backache After Spinal Anesthesia: A Pragmatic Randomized Controlled Trial
Authors: Choi Jeong Sil , Chang Sun Ju
Published: July 2017

Background

Although bed rest is recommended after spinal anesthesia to prevent the occurrence of post‐dural puncture headache, current literature suggests that periods of bed rest did not prevent headache as well as increase the risk of other complications such as backache. However, information is scarce regarding an appropriate period of bed rest following a dural puncture.

Aim

The aim of this study was to compare the incidence of post‐dural puncture headache and backache after different periods of bed rest following spinal anesthesia.

Methods

This study was a pragmatic, parallel‐group, blinded, and randomized controlled trial (trial registration number KCT0001797). A total of 119 patients who underwent surgery under spinal anesthesia participated in this study from December 2013 to June 2014. The participants were randomly allocated to three groups: the immediate mobilization group (n = 45), 4‐hour bed rest group (n = 40), and 6‐hour bed rest group (n = 34). The severity of headache and backache was measured using the Dittmann scale and a visual analogue scale, respectively. Data were collected for 5 consecutive days postoperatively by one researcher blind to the group allocation.

Results

No significant difference in the incidence of headache among the three groups was detected. However, the incidence of backache in the 6‐hour bed rest group was higher and was significantly more severe than the other groups.

Linking Evidence to Action

Bed rest after spinal anesthesia did not prevent the occurrence of headache and increased the incidence of patients experiencing a backache and, therefore, is not recommended. The findings provide information for establishing evidence‐based nursing practices for patients after a dural puncture.
Systematic Review of Psychosocial Interventions for People With Spinal Cord Injury During Inpatient Rehabilitation: Implications for Evidence‐Based Practice
Authors: Li Yan , Bressington Daniel , Chien Wai Tong
Published: July 2017

Background

The bio‐psychosocial model of spinal cord injury (SCI) highlights that psychosocial care is of equal importance as physical rehabilitation, and should be offered in the earlier stages of inpatient rehabilitation.

Aim

This systematic review aimed to identify interventional research regarding psychosocial care for people with SCI during inpatient rehabilitation and synthesize the evidence of the effects and characteristics of these studies.

Methods

A systematic search of relevant literature published between 1985 to July 2016 was conducted with six databases (Scopus, MEDLINE, CINAHL, Science Citation Index Expanded, PsycINFO, and the China Academic Journal Full‐text Database). Reference lists of the identified articles were reviewed to find additional relevant articles.

Results

A total of four randomized controlled trials and seven non‐randomized controlled trials were included in this review. The interventions focused on specialized types of SCI population with relatively high levels of psychological distress, pain or pressure ulcers. Studies reported some varied or inconsistent improvements in participants’ cognitive appraisal, psychosocial adaptation or mental health but there were no significant effects on their coping ability. Due to the heterogeneity of the studies, findings were synthesized narratively without conducting meta‐analysis.

Linking Evidence to Action

This review found promising evidence that approaches to psychosocial care for people with SCI can improve their cognitive appraisal and psychosocial adaptation. Significant methodological limitations weakened study findings. Additionally, because studies were conducted in only a few developed countries with subgroups of patients having specific illness characteristics or severity, their generalizability to the wider SCI population is uncertain. Therefore, future research should adopt more robust study designs to test psychosocial interventions for SCI patients with different socio‐cultural backgrounds and psychological adjustment conditions in the early stages of rehabilitation.
Results of an Integrative Analysis: A Call for Contextualizing HIV and AIDS Clinical Practice Guidelines to Support Evidence‐Based Practice
Authors: Edwards Nancy , Kahwa Eulalia , Hoogeveen Katie
Published: July 2017

Background

Practice guidelines aim to improve the standard of care for people living with HIV/AIDS. Successfully implementing guidelines requires tailoring them to populations served and to social and organizational influences on care.

Aims

To examine dimensions of context, which nurses and midwives described as having a significant impact on their care of patients living with HIV/AIDS in Kenya, Uganda, South Africa, and Jamaica and to determine whether HIV/AIDS guidelines include adaptations congruent with these dimensions of context.

Methods

Two sets of data were used. The first came from a qualitative study. In‐depth interviews were conducted with purposively selected nurses, midwives, and nurse managers from 21 districts in four study countries. A coding framework was iteratively developed and themes inductively identified. Context dimensions were derived from these themes. A second data set of published guidelines for HIV/AIDS care was then assembled. Guidelines were identified through Google and PubMed searches. Using a deductive integrative analysis approach, text related to context dimensions was extracted from guidelines and categorized into problem and strategy statements.

Results

Ninety‐six individuals participated in qualitative interviews. Four discrete dimensions of context were identified: health workforce adequacy, workplace exposure risk, workplace consequences for nurses living with HIV/AIDS, and the intersection of work and family life. Guidelines most often acknowledged health human resource constraints and presented mitigation strategies to offset them, and least often discussed workplace consequences and the intersections of family and work life.

Linking Evidence to Action

Guidelines should more consistently acknowledge diverse implementation contexts, propose how recommendations can be adapted to these realities, and suggest what role frontline healthcare providers have in realizing the structural changes necessary for healthier work environments and better patient care. Guideline recommendations should include more explicit advice on adapting their recommendations to different care conditions.
A randomized controlled trial to evaluate the effects of dietary fibre from distillers grains on enterohemorrhagic Escherichia coli detection from the rectoanal mucosa and hides of feedlot steers
Authors: Schneider L. G. , Klopfenstein T. J. , Stromberg Z. R. , Lewis G. L. , Erickson G. E. , Moxley R. A. , Smith D. R.
Published: July 2017

Feeding high levels (≥40% dry matter) of distillers grains may increase the risk for cattle to carry enterohemorrhagic Escherichia coli (EHEC) O157. The mechanism for the increased risk is not known nor whether non‐O157 EHEC are similarly affected. Our objective was to test whether the fibre content or other components of modified distillers grains plus solubles (MDGS) affects the probability for cattle to carry EHEC serogroups of public health importance. A 2 × 2 plus 1 factorial treatment arrangement within a randomized block design was utilized. Within each of four blocks, 25 feedlot pens (n = 8 steers/pen) were assigned randomly to (i) corn‐based control diet; (ii) 20% dry matter (DM) MDGS; (iii) 40% DM MDGS; (iv) corn bran added to corn‐based diet to match fibre of 20% MDGS or (v) 40% MDGS. Rectoanal mucosa swabs (RAMS) were collected on day (d)0, d35, d70 and d105; hide swabs were collected on the last feeding day. Samples were tested for EHEC by a molecular screening assay. The effects of fibre source and fibre level on EHEC carriage were tested using multilevel logistic regression (generalized linear mixed models; α = 0.05). EHEC O45 RAMS detection was associated with fibre level, source and sampling day. EHEC O103 RAMS detection increased by feeding 40% MDGS but not the corresponding corn bran diet. Hide contamination by EHEC O45 or O103 was less likely in cattle fed MDGS compared to corn bran diets. EHEC O111 RAMS detection decreased by feeding 40% MDGS but not by feeding the corresponding corn bran diet. Detection of EHEC O157 or O145 was not associated with dietary factors. Feeding 40% MDGS increased the probability for carriage of some EHEC serogroups but decreased probability of others, which indicated that EHEC serogroups have different risk factors associated with feeding MDGS and little association with dietary fibre.
A Unique and Rational Applications Methodology for Fiber Composite Laminates
Authors: Christensen Richard M.
Published: July 2017

An applications methodology is synthesized from the research-based development of failure theory for orthotropic fiber composite laminates. In effect, this work continues and completes the work of Christensen (2017, “Lamination Theory for the Strength of Fiber Composite Materials,” ASME J. Appl. Mech., 84(7), p. 071007). This failure theory applies for the condition of fiber-dominated behavior, appropriate to carbon fiber—polymeric matrix composites and such similar systems. A lamination theory for stiffness and a separate lamination theory for strength are the outcomes derived here. Final forms are given for 0, 90, ± 45 type orthotropic laminates, with the four lamina orientation volume fractions to be specified in any particular application of interest. Many examples are given of using the new methodology in specific design cases.
Fractional Convection
Authors: Li Changpin , Yi Qian , Kurths Jürgen
Published: July 2017

In this study, we describe the fractional convection operator for the first time and present its discrete form with second-order convergence. A numerical scheme for the fractional-convection–diffusion equation is also constructed in order to get insight into the fractional convection behavior visually. Then, we study the fractional-convection-dominated diffusion equation which has never been considered, where the diffusion is normal and is characterized by the Laplacian. The interesting fractional convection phenomena are observed through numerical simulation. Moreover, we investigate the fractional-convection-dominated-diffusion equation which is studied for the first time either, where the convection and the diffusion are both in the fractional sense. The corresponding fractional convection phenomena are displayed via computer graphics as well.
Posing Multibody Dynamics With Friction and Contact as a Differential Complementarity Problem
Authors: Negrut Dan , Serban Radu , Tasora Alessandro
Published: July 2017

This technical brief revisits the method outlined in Tasora and Anitescu 2011 [“A Matrix-Free Cone Complementarity Approach for Solving Large-Scale, Nonsmooth, Rigid Body Dynamics,” Comput. Methods Appl. Mech. Eng., 200(5–8), pp. 439–453], which was introduced to solve the rigid multibody dynamics problem in the presence of friction and contact. The discretized equations of motion obtained here are identical to the ones in Tasora and Anitescu 2011 [“A Matrix-Free Cone Complementarity Approach for Solving Large-Scale, Nonsmooth, Rigid Body Dynamics,” Comput. Methods Appl. Mech. Eng., 200(5–8), pp. 439–453]; what is different is the process of obtaining these equations. Instead of using maximum dissipation conditions as the basis for the Coulomb friction model, the approach detailed uses complementarity conditions that combine with contact unilateral constraints to augment the classical index-3 differential algebraic equations of multibody dynamics. The resulting set of differential, algebraic, and complementarity equations is relaxed after time discretization to a cone complementarity problem (CCP) whose solution represents the first-order optimality condition of a quadratic program with conic constraints. The method discussed herein has proven reliable in handling large frictional contact problems. Recently, it has been used with promising results in fluid–solid interaction applications. Alas, this solution is not perfect, and it is hoped that the detailed account provided herein will serve as a starting point for future improvements.
Nonfragile Fuzzy Output Feedback Synchronization of a New Chaotic System: Design and Implementation
Authors: Azarang A. , Miri M. , Kamaei S. , Asemani M. H.
Published: July 2017

A new three-dimensional (3D) chaotic system is proposed with four nonlinear terms which include two quadratic terms. To analyze the dynamical properties of the new system, mathematical tools such as Lyapunov exponents (LEs), Kaplan–York dimensions, observability constants, and bifurcation diagram have been exploited. The results of these calculations verify the specific features of the new system and further determine the effect of different system parameters on its dynamics. The proposed system has been experimentally implemented as an analog circuit which practically confirms its predicted chaotic behavior. Moreover, the problem of master–slave synchronization of the proposed chaotic system is considered. To solve this problem, we propose a new method for designing a nonfragile Takagi–Sugeno (T–S) fuzzy static output feedback synchronizing controller for a general chaotic T–S system and applied the method to the proposed system. Some practical advantages are achieved employing the new nonlinear controller as well as using system output data instead of the full-state data and considering gain variations because of the uncertainty in values of practical components used in implementation the controller. Then, the designed controller has been realized using analog devices to synchronize two circuits with the proposed chaotic dynamics. Experimental results show that the proposed nonfragile controller successfully synchronizes the chaotic circuits even with inexact analog devices.
Iterative Refinement of Accelerations in Real-Time Vehicle Dynamics
Authors: Pan Yongjun , de Jalón Javier García
Published: July 2017

A number of strategies can be followed for the real-time simulation of multibody systems. The main contributing factor to computational efficiency is usually the algorithm itself (the number of equations and their structure, the number of coordinates, the time integration scheme, etc.). Additional (but equally important) aspects have to do with implementation (linear solvers, sparse matrices, parallel computing, etc.). In this paper, an iterative refinement technique is introduced into a semirecursive multibody formulation. First, the formulation is summarized and its basic features are highlighted. Then, the basic goal is to iteratively solve the fundamental system of equations to obtain the accelerations. The iterative process is applied to compute corrections of the solution in an economic way, terminating as soon as a given precision is reached. We show that, upon implementation of this method, the computation time can be reduced at a very low implementation and accuracy costs. Two vehicles are simulated to prove the numerical benefits, namely a 16-degrees-of-freedom (DOF) sedan vehicle and a 40-degrees-of-freedom semitrailer truck. In short, a simple method to iteratively solve for the accelerations of vehicle systems in an efficient way is presented.
The Transport Dynamics Induced by Riesz Potential in Modeling Fractional Reaction–Diffusion-Mechanics System
Authors: Saha Ray S.
Published: July 2017

This paper comprises of a finite difference method with implicit scheme for the Riesz fractional reaction–diffusion equation (RFRDE) by utilizing the fractional-centered difference for approximating the Riesz derivative, and consequently, we obtain an implicit scheme which is proved to be convergent and unconditionally stable. Also a novel analytical approximate method has been dealt with namely optimal homotopy asymptotic method (OHAM) to investigate the solution of RFRDE. The numerical solutions of RFRDE obtained by proposed implicit finite difference method have been compared with the solutions of OHAM and also with the exact solutions. The comparative study of the results establishes the accuracy and efficiency of the techniques in solving RFRDE. The proposed OHAM renders a simple and robust way for the controllability and adjustment of the convergence region and is applicable to solve RFRDE.
Incipient Bearing Fault Feature Extraction Based on Minimum Entropy Deconvolution and K-Singular Value Decomposition
Authors: Dong Guangming , Chen Jin , Zhao Fagang
Published: July 2017

Machinery condition monitoring and fault diagnosis are essential for early detection of equipment malfunctions or failures, which insure productivity, quality, and safety in the manufacturing process. This paper aims at extracting fault features of rolling element bearings at the incipient fault stage. K-singular value decomposition (K-SVD), one technique for sparse representation of signals, is used for study. In K-SVD, its dictionary is trained from data by machine learning techniques, which allows more flexibility to adapt to variation of real signals than the predefined dictionaries. Analysis on simulated bearing signals and real signals shows that K-SVD can give better bearing fault features than the predefined dictionaries such as wavelet dictionaries. However, during our simulation study, K-SVD was found to have large representation error under heavy noise. To reduce the noise effect, minimum entropy deconvolution (MED) is used as a prefilter. The combination of MED and K-SVD is proposed for incipient bearing fault detection. The method is verified by simulation and experimental study. It is shown that the proposed method can effectively extract the impulsive fault feature of the tested bearing at its incipient fault stage.
A Generalized and Efficient Approach for Accurate Five-Axis Flute Grinding of Cylindrical End-Mills
Authors: Ren Lei , Wang Shilong , Yi Lili
Published: July 2017

Wheel position (including wheel location and orientation) in the flute grinding process of an end-mill determines the ground flute's geometric parameters, i.e., rake angle, core radius, and flute width. Current technologies for calculating the wheel position to guarantee the three parameters' accuracy are either time-consuming or only applicable to the grinding wheels with singular points. In order to cope with this problem, this paper presents a generalized and efficient approach for determining the wheel position accurately in five-axis flute grinding of cylindrical end-mills. A new analytic expression of the wheel location is derived and an original algorithm is developed to search for the required wheel position. This approach can apply not only to the wheels with fillets but also to the wheels with singular points. Simulation examples are provided to validate the new approach and compared with the results from other literature. Besides the ability to determine the wheel position, the new approach can evaluate extrema of the core radius and flute width that a specified wheel can generate. Owing to the evaluated extrema, automatic 1V1 wheel customization according to the designed flute is realized in this paper. This work can improve the efficiency and automation degree of the flute grinding process and lay a good foundation for the development of a comprehensive computer-aided design and computer-aided manufacturing system for end-mill manufacturing.
A Computational Study of Mixed Convection Heat Transfer From a Continuously Moving Isothermal Vertical Plate to Alumina–Water Nanofluid as in Hot Extrusion
Authors: Mahapatra Arijit , Ghoshdastidar P. S.
Published: July 2017

The paper presents a computational study of steady, laminar, two-dimensional (2D) mixed convection heat transfer from a continuously moving isothermal vertical plate to alumina–water nanofluid as in hot extrusion. The simulation is based on a heterogeneous flow model which takes into account Brownian diffusion and thermophoresis of nanoparticles. The finite difference method is used to discretize the governing equations. The SIMPLE algorithm has been applied to obtain flow, thermal, and nanoparticle concentration fields. The numerical results have been validated satisfactorily with the published results for pure fluids. A detailed parametric study reveals that in the mixed convection regime, the enhancement factor (EF) (defined as the ratio of average heat transfer coefficient in nanofluid to that in base fluid) increases with nanoparticle concentration. The enhancement is more at lower Richardson number (Gr/Re2), that is, closer to forced convection regime. In the regime close to free convection, the EF is found to be very small. Larger plate velocity (that is, higher Reynolds number) has a positive effect on heat transfer enhancement but higher plate-fluid temperature difference results in lower EF. An enhancement in heat transfer coefficient as high as 22% is realized at the plate velocity of 0.4 m/s. The effectiveness (defined as the ratio of average heat transfer coefficient in nanofluid to the power required to pull the plate), in general, falls with higher volume fraction of nanoparticles and plate velocity and escalates with a rise in Richardson number and plate-fluid temperature difference.
Analytical Model for Prediction of Residual Stress in Dynamic Orthogonal Cutting Process
Authors: Huang Xin-Da , Zhang Xiao-Ming , Leopold Jürgen , Ding Han
Published: July 2017

Residual stress, characteristic of surface integrity, is a great issue in cutting process for its significant effects on fatigue life and dimension stability of the machined parts. From a practical viewpoint, residual stress is generated in a dynamic tool-part engagement process, instead of a process with nominal cutting loads. This is the challenge that we have to handle, so as to achieve better predictive methods than the previously recorded approaches in literatures which ignore the dynamic effects on residual stress. This paper presents an analytical method for the prediction of residual stress in dynamic orthogonal cutting. A mechanistic model of the dynamic orthogonal cutting is provided, considering the indentation effect of the cutting edge during the wave-on-wave cutting process. Following the calculation of plastic strains by incremental analysis in mechanical loading, analytical solution of the residual stress due to distributed plastic strains in half-plane is obtained based on inclusion theory. Without relaxation procedures, the two-dimensional (2D) distribution of residual stress in dynamic cutting process is predicted for the first time. A delicately designed dynamic orthogonal cutting experiment is realized through numerical control (NC) lathe. The periodic residual stress distribution is predicted using the proposed approach, which is then validated against the X-ray diffraction measurements.
Modeling and Simulation of a Selective Laser Foaming Process for Fabrication of Microliter Tissue Engineering Scaffolds
Authors: Ock JinGyu , Li Wei
Published: July 2017

Selective laser foaming is a novel process that combines solid-state foaming and laser ablation to fabricate an array of microliter tissue engineering scaffolds on a polymeric chip for biomedical applications. In this study, a finite element analysis (FEA) model is developed to investigate the effect of laser processing parameters. Experimental results with biodegradable polylactic acid (PLA) were used for validation. It is found that foaming always occurs before ablation, and once it occurs, the temperature increases dramatically due to an enhanced laser absorption effect of the porous structure. The geometry of the fabricated scaffolds can be controlled by laser parameters. While the depth of scaffolds can be controlled by laser power and lasing time, the diameter is more effectively controlled by the laser power. The model developed in this study can be used to optimize and control the selective foaming process.
Effects of Laser Radiation on the Wetting and Diffusion Characteristics of Kovar Alloy on Borosilicate Glass
Authors: Zhang Min , Lawrence Yao Y. , Jun Chen Chang , Kongsuwan Panjawat , Brandal Grant , Bian Dakai
Published: July 2017

The purpose of this study was to investigate the advantages of laser surface melting for improving wetting over the traditional approach. For comparison, kovar alloy was preoxidized in atmosphere at 700 °C for 10 min, and then wetted with borosilicate glass powder at 1100 °C with different holding time in atmosphere. The proposed approach used a Nd:YAG laser to melt the surface of the kovar alloy sample in atmosphere, then wetted with borosilicate glass powder at 1100 °C with the same holding time. The laser melted surface shows a decrease in contact angle (CA) from 47.5 deg to 38 deg after 100 min. X-ray photoelectron spectroscopy (XPS) analysis shows that the surface and adjacent depth have higher concentration of FeO for laser treated kovar (Kovar(L)) than that on traditional thermal treated kovar (kovar(P)). This is attributed to the following improved wetting and diffusion process. The adhesive oxide layer formed on kovar (L) may enhance the oxygen diffusion into the substrate and iron diffusion outward to form an outside layer. This is an another way to enhance the wetting and diffusion process when compared to the delaminated oxide scales formed on kovar (P) surface. The diffusion mechanisms were discussed for both approaches. Scanning electron microscope (SEM) revealed that an iron oxide interlayer in the joint existed under both conditions. Fayalite nucleated on the iron oxide layer alloy and grew into the glass. In both cases, neither Co nor Ni were involved in the chemical bonding during wetting process. The work has shown that laser surface melting can be used to alter the wetting and diffusion characteristics of kovar alloy onto borosilicate glass.
A Novel Incremental Sheet Bending Process of Complex Curved Steel Plate
Authors: Zuo Qiyang , He Kai , Dang Xiaobing , Feng Wei , Du Ruxu
Published: July 2017

Bending complex curved steel plates for constructing ship hull has long been a challenge in shipbuilding industry. This paper presents a novel incremental bending process to obtain complicated curved steel plates by a series of sequential and layered punches. Taking advantage of this process, the blank plate that is fixed and held by a flexible supporting system can incrementally be bent into the target shape by a press tool along a planned tool path step by step and layer by layer. Acting as a “lower die,” the flexible supporting system can provide flexible and multifunctional supports for the work piece during the forming process, whose four general motion modes are demonstrated in this paper. Meanwhile, the procedures of tool path planning and forming layering are also explained in detail. In addition, aiming at different motion modes of the flexible supporting system, two springback compensation methods are given. Furthermore, according to the forming principle presented in this paper, an original incremental prototype equipment was designed and manufactured, which is mainly composed of a three-axis computer numerical control (CNC) machine, a flexible supporting system, and a three-dimensional (3D) scanning feedback system. A series of forming experiments focusing on a gradual curvature shape were carried out using this prototype to investigate the feasibility and validity of this forming process.
GDFE: Geometry-Driven Finite Element for Four-Dimensional Printing
Authors: Kwok Tsz-Ho , Chen Yong
Published: July 2017

Four-dimensional (4D) printing is a new category of printing that expands the fabrication process to include time as the fourth dimension, and its simulation and planning need to take time into consideration as well. The common tool for estimating the behavior of a deformable object is the finite element method (FEM). However, there are various sources of deformation in 4D printing, e.g., hardware and material settings. To model the behavior by FEM, a complete understanding of the process is needed and a mathematical model should be established for the structure–property–process relationship. However, the relationship is usually complicated, which requires different kinds of testing to formulate such models due to the process complexity. With the insight that the characteristic of shape change is the primary focus in 4D printing, this paper introduces geometry-driven finite element (GDFE) to simplify the modeling process by inducing deformation behavior from a few physical experiments. The principle of GDFE is based on the relationship between material structure and shape transformation. Accordingly, a deformation simulation can be developed for 4D printing by applying the principles to the GDFEs. The GDFE framework provides an intuitive and effective way to enable simulation and planning for 4D printing even when a complete mathematical model of new material is not available yet. The use of the GDFE framework for some applications is also presented in this paper.
Fabrication of Inner Grooved Hollow Fiber Membranes Using Microstructured Spinneret for Nerve Regeneration
Authors: Yin Jun , Wang Zonghuan , Chai Wenxuan , Dai Guangli , Suo Hairui , Zhang Ning , Wen Xuejun , Huang Yong
Published: July 2017

Nerve conduits with topographical guidance have been recognized as the efficient repair of damaged peripheral nerves. In this study, polymeric hollow fiber membranes (HFMs) with grooved inner surface have been fabricated from a microstructured spinneret using a dry-jet wet spinning process for nerve regeneration studies. The effectiveness of HFM inner grooves has been demonstrated during an in vitro study of chick forebrain neuron outgrowth. It is of great importance that the groove geometry can be controllable to meet various needs in promoting nerve regeneration performance. While the overall groove geometry is determined by the spinneret design, fabrication conditions are also indispensable in fine-tuning the final groove geometry such as the groove height and width on the order of 10 μm or less. It is found that the bore fluid flow rate can be utilized to effectively adjust the resulting groove height by at most 52% and groove width by at most 61%, respectively, without modifying the spinneret geometry. This enables a new approach to fabricate different grooved HFMs using the same spinneret. By comparing to the influences of bore fluid flow rate, the dope fluid flow rate is less effective in regulating the groove height and width when using the same microstructured spinneret. Both bore and dope fluid flow rates should be carefully selected for fine groove width tuning.
Ball Burnishing Under High Velocities Using a New Rolling Tool Concept
Authors: Hiegemann Lars , Erman Tekkaya A.
Published: July 2017

Ball burnishing is a process used to smooth rough surfaces. For not rotational symmetric parts, the process is typically conducted on milling machines. Since it is an incremental process, it is relatively time consuming. Therefore, a rolling tool is developed, which superposes the rotation of the milling spindle with the feed of the machine to increase the rolling velocity. In order to achieve constant rolling forces, hydrostatic ball-burnishing tools are used. Within this work, the influence of this tool concept on the processing time as well as on the leveling of surface irregularities is investigated. This is achieved by a comparison with a conventional ball-burnishing process. Finally, the rotating tool is used to investigate the influence of high rolling speeds on the leveling of the surface. All experiments were carried out with thermally coated specimens. A model for calculating the strain rates at the roughness peaks during ball burnishing is derived. For the experiments carried out with the rotating rolling tool, rolling velocities of 50,000 mm/min were realized. Calculations with the developed model showed that this results in local strain rates at the roughness peaks of up to 1384 s−1. In addition, the flow stresses at the roughness peaks were calculated. Compared with quasi-static experiments, the flow stress drops to less than the half under high velocities. This results in a better leveling of the surface for rolling velocities between 10,000 mm/min and 25,000 mm/min. A further rise of the rolling speed increases the flow stress again and thereby reduces the possible leveling.
In Situ Observations and Pressure Measurements for Autoclave Co-Cure of Honeycomb Core Sandwich Structures
Authors: Anders Mark , Zebrine Daniel , Centea Timotei , Nutt Steven
Published: July 2017

In this article, we describe an experimental method for investigating the autoclave co-cure of honeycomb core composite sandwich structures. The design and capabilities of a custom-built, lab-scale “in situ co-cure fixture” are presented, including procedures and representative results for three types of experiments. The first type of experiment involves measuring changes in gas pressure on either side of a prepreg laminate to determine the prepreg air permeability. The second type involves co-curing composite samples using regulated, constant pressures, to study material behaviors in controlled conditions. For the final type, “realistic” co-cure, samples are processed in conditions mimicking autoclave cure, where the gas pressure in the honeycomb core evolves naturally due to the competing effects of air evacuation and moisture desorption from the core cell walls. The in situ co-cure fixture contains temperature and pressure sensors, and derives its name from a glass window that enables direct visual observation of the skin/core bond-line during processing, shedding light on physical phenomena that are not observable in a traditional manufacturing setting. The experiments presented here are a first step within a larger research effort, whose long-term goal is to develop a physics-based process model for autoclave co-cure.
An Unsupervised Machine Learning Approach to Assessing Designer Performance During Physical Prototyping
Authors: Dering Matthew L. , Tucker Conrad S. , Kumara Soundar
Published: July 2017

An important part of the engineering design process is prototyping, where designers build and test their designs. This process is typically iterative, time consuming, and manual in nature. For a given task, there are multiple objects that can be used, each with different time units associated with accomplishing the task. Current methods for reducing time spent during the prototyping process have focused primarily on optimizing designer to designer interactions, as opposed to designer to tool interactions. Advancements in commercially available sensing systems (e.g., the Kinect) and machine learning algorithms have opened the pathway toward real-time observation of designer's behavior in engineering workspaces during prototype construction. Toward this end, this work hypothesizes that an object O being used for task i is distinguishable from object O being used for task j, where i is the correct task and j is the incorrect task. The contributions of this work are: (i) the ability to recognize these objects in a free roaming engineering workshop environment and (ii) the ability to distinguish between the correct and incorrect use of objects used during a prototyping task. By distinguishing the difference between correct and incorrect uses, incorrect behavior (which often results in wasted time and materials) can be detected and quickly corrected. The method presented in this work learns as designers use objects, and infers the proper way to use them during prototyping. In order to demonstrate the effectiveness of the proposed method, a case study is presented in which participants in an engineering design workshop are asked to perform correct and incorrect tasks with a tool. The participants' movements are analyzed by an unsupervised clustering algorithm to determine if there is a statistical difference between tasks being performed correctly and incorrectly. Clusters which are a plurality incorrect are found to be significantly distinct for each node considered by the method, each with p ≪ 0.001.
Application of Feature-Learning Methods Toward Product Usage Context Identification and Comfort Prediction
Authors: Ghosh Dipanjan , Olewnik Andrew , Lewis Kemper
Published: July 2017

Usage context is considered a critical driving factor for customers' product choices. In addition, physical use of a product (i.e., user-product interaction) dictates a number of customer perceptions (e.g., level of comfort). In the emerging internet of things (IoT), this work hypothesizes that it is possible to understand product usage and level of comfort while it is “in-use” by capturing the user-product interaction data. Mining this data to understand both the usage context and the comfort of the user adds new capabilities to product design. There has been tremendous progress in the field of data analytics, but the application in product design is still nascent. In this work, application of feature-learning methods for the identification of product usage context and level of comfort is demonstrated, where usage context is limited to the activity of the user. A novel generic architecture using foundations in convolutional neural network (CNN) is developed and applied to a walking activity classification using smartphone accelerometer data. Results are compared with feature-based machine learning algorithms (neural network and support vector machines (SVM)) and demonstrate the benefits of using the feature-learning methods over the feature-based machine-learning algorithms. To demonstrate the generic nature of the architecture, an application toward comfort level prediction is presented using force sensor data from a sensor-integrated shoe.
A Dynamical Model of Drop Spreading in Electrohydrodynamic Jet Printing
Authors: Pannier Christopher P. , Diagne Mamadou , Spiegel Isaac A. , Hoelzle David J. , Barton Kira
Published: July 2017

Electrohydrodynamic jet (e-jet) printing is a microscale additive manufacturing technique used to print microscale constructs, including next-generation biological and optical sensors. Despite the many advantages to e-jet over competing microscale additive manufacturing techniques, there do not exist validated models of build material drop formation in e-jet, relegating process design and control to be heuristic and ad hoc. This work provides a model to map deposited drop volume to final spread topography and validates this model over the drop volume range of 0.68–13.4 pL. The model couples a spherical cap volume conservation law to a molecular kinetic relationship for contact line velocity and assumes an initial contact angle of 180 deg to predict the drop shape dynamics of dynamic contact angle and dynamic base radius. For validation, the spreading of e-jet-printed drops of a viscous adhesive is captured by high-speed microscopy. Our model is validated to have a relative error less than 3% in dynamic contact angle and 1% in dynamic base radius.
Effect of Different Heat Treatments on Mechanical Properties of Laser Sintered Additive Manufactured Parts
Authors: Sarkar Sagar , Kumar Cheruvu Siva , Nath Ashish Kumar
Published: July 2017

One of the most popular additive manufacturing processes is laser-based direct metal laser sintering (DMLS) process, which enables us to make complex three-dimensional (3D) parts directly from computer-aided design models. Due to layer-by-layer formation, parts built in this process tend to be anisotropic in nature. Suitable heat treatment can reduce this anisotropic behavior by changing the microstructure. Depending upon the applications, a wide range of mechanical properties can be achieved between 482 °C and 621 °C temperature for precipitation-hardened stainless steels. In the present study, effect of different heat treatment processes, namely solution annealing, aging, and overaging, on tensile strength, hardness, and wear properties has been studied in detail. Suitable metallurgical and mechanical characterization techniques have been applied wherever required, to support the experimental observations. Results show H900 condition gives highest yield strength and lowest tensile strain at break, whereas solution annealing gives lowest yield strength and as-built condition gives highest tensile strain at break. Scanning electron microscope (SEM) images show that H900 and H1150 condition produces brittle and ductile morphology, respectively, which in turn gives highest and lowest hardness value, respectively. X-ray diffraction (XRD) analysis shows presence of austenite phases, which can increase ductility at the cost of hardness. Average wear loss for H900 condition is highest, whereas it is lowest for solution annealed condition. Further optical and SEM images have been taken to understand the basic wear mechanism involved.
Residual Stress Distribution and the Concept of Total Fatigue Stress in Laser and Mechanically Formed Commercially Pure Grade 2 Titanium Alloy Plates
Authors: Mjali Kadephi V. , Els-Botes Annelize , Mashinini Peter M.
Published: July 2017

This paper discusses the investigation of residual stresses developed as a result of mechanical and laser forming processes in commercially pure grade 2 titanium alloy plates as well as the concept of total fatigue stress (TFS). The intention of the study was to bend the plates using the respective processes to a final radius of 120 mm using both processes. The hole drilling method was used to measure residual strains in all the plates. High stress gradients were witnessed in the current research and possible cases analyzed and investigated. The effects of processing speeds and powers used also played a significant role in the residual stress distribution in all the formed plates. A change in laser power resulted in changes to residual stress distribution in the plates evaluated. This study also dwells into how the loads that are not normally incorporated in fatigue testing influence fatigue life of commercially pure grade 2 titanium alloy plates. Also, the parent material was used to benchmark the performance of the two forming processes in terms of stresses developed. Residual stresses developed from the two forming processes and those obtained from the parent material were used. The residual stress values were then added to the mean stress and the alternating stress from the fatigue machine to develop the concept of TFS. This exercise indicated the effect of these stresses on the fatigue life of the parent material, laser and mechanically formed plate samples. A strong link between these stresses was obtained and formulae explaining the relationship were formulated. A comparison between theory and practical application shown by test results is found to be satisfactory in explaining concerns that may arise. The laser forming process is more influential in the development of residual stress, compared to the mechanical forming process. With each parameter change in laser forming, there is a change in residual stress arrangement. Under the influence of laser forming, the stress is more tensile in nature making the laser formed plate specimens more susceptible to early fatigue failure. The laser and mechanical forming processes involve bending of the plate samples and most of these samples experienced a two-dimensional defect, which is a dislocation. The dislocation is the defect responsible for the phenomenon of slip by which most metals deform plastically. Also, the high temperatures experienced in laser forming were one of the major driving factors in bending.
Procedure for Selecting Key Performance Indicators for Sustainable Manufacturing
Authors: Kibira Deogratias , Brundage Michael P. , Feng Shaw , Morris K. C.
Published: July 2017

The need for an open, inclusive, and neutral procedure in selecting key performance indicators (KPIs) for sustainable manufacturing has been increasing. The reason is that manufacturers seek to determine what to measure to improve environmental sustainability of their products and manufacturing processes. A difficulty arises in understanding and selecting specific indicators from many stand-alone indicator sets available. This paper presents a procedure for individual manufacturers to select KPIs for measuring, monitoring, and improving environmental aspects of manufacturing processes. The procedure is the basis for a guideline, being proposed for standardization within ASTM International. That guide can be used for (1) identifying candidate KPIs from existing sources, (2) defining new candidate KPIs, (3) selecting appropriate KPIs based on KPI criteria, and (4) composing the selected KPIs with assigned weights into a set. The paper explains how the developed procedure complements existing indicator sets and sustainability-measurement approaches at the manufacturing process level.