bluuebunny/crossref_metadata_2025 huggingface dataset:
Intraneural perineuriomas: diagnostic value of magnetic resonance neurography
Authors: León Cejas Luciana , Binaghi Daniela , Socolovsky Mariano , Dubrovsky Alberto , Pirra Laura , Marchesoni Cintia , Pardal Ana , Monges Soledad , Peretti Gabriela , Taratuto Ana L. , Lubinieki Fabiana , Reisin Ricardo
Published: November 2017

Intraneural perineurioma (IP) is an under‐recognized hypertrophic peripheral nerve tumor. It affects young patients involving frequently the sciatic nerve and its branches and presents with a progressive, painless and predominantly motor deficit. Magnetic resonance neurography (MRN) is a useful tool to localize the lesion, evaluate its extension, and discriminate between different etiologies. We reviewed the clinical records of 11 patients with pathologically confirm IP. Eight patients were males with mean age 19 years. Initial complains were unilateral steppage (seven patients), bilateral steppage (one patient), unilateral gastrocnemius wasting (one patient), unilateral thigh atrophy (one patient), and unilateral hand weakness (one patient). Nine patients had mild painless sensory loss. Examinations revealed involvement of sciatic nerve extending into the peroneal nerve (eight patients), posterior tibial nerve (one patient), radial nerve (one patient), and femoral nerve (one patient). MRN revealed enlargement of the affected nerve isointense on T1‐weighted, hyperintense on T2 fat‐saturated images, and with avid enhancement on post‐contrast imaging. In all patients, a nerve biopsy confirmed the diagnosis. MRN allows early and non‐invasive identification of this tumor and is a key tool providing localization and differential diagnosis in patients with slowly progressive focal neuropathies.
Comparison of effacement curve with dilatation curve for prediction of labor progression
Authors: Agah Jila , Baghani Roya , Nazarzadeh Milad , Borna Sedigheh
Published: November 2017

Aim

This study was conducted to evaluate the ability of the effacement curve to predict fetal descent by comparing it to dilatation in order to improve the accuracy of the current partogram.

Method

We conducted an observational study of women who were admitted for vaginal delivery at Mobini Hospital, Sabzevar, Iran in 2015. During labor, dilatation and effacement were plotted in different graphs and then their association with fetal descent was separately evaluated and compared. This assessment was performed in two groups: primipara and multipara.

Results

From 1750 individuals, 503 primiparous and 512 multiparous women were eligible for the study. An adjusted generalized estimating equations multivariable model showed both dilatation and effacement had a significant relationship with fetal descent either in primipara or multipara. In primipara, the prediction value of effacement equalled dilatation (β,eff 0.29, P < 0.001; β,dil 0.30, P < 0.001). In multipara, the prediction value of effacement was obviously higher than dilatation (β,eff 0.45, P < 0.001; β,dil 0.27, P < 0.001). The strength of effacement to predict labor in multipara was clearly greater than in primipara (β,eff 0.45 and β,eff 0.29, respectively). The strength of dilatation to predict labor in multipara was comparable to primipara (β,dil 0.27 and β,dil: 0.30, respectively).

Conclusions

Regarding the acceptable predictive value of effacement, we believe considering effacement, dilatation and station curves altogether can improve the power of the existing partogram for the assessment of labor progression and detection of failure to progress.
Uterine metastasis of lung adenocarcinoma under molecular target therapy with epidermal growth factor receptor tyrosine kinase inhibitors: A case report and review of the literature
Authors: Shibata Mayu , Shizu Masato , Watanabe Kazuko , Takeda Akihiro
Published: November 2017

A 63‐year‐old woman presented with abnormal vaginal bleeding. Her disease history was significant, and included advanced lung adenocarcinoma with a deletion mutation in exon 19 of the epidermal growth factor receptor (EGFR) gene, which was managed by concurrent chemoradiotherapy, followed by molecular targeted therapy with tyrosine kinase inhibitors (TKIs) for a two‐year period. Contrast‐enhanced computed tomography showed the enlargement of a previously suspicious myoma node, with peripheral enhancement. Hemorrhagic necrosis was also observed on magnetic resonance imaging. Transabdominal hysterectomy and bilateral salpingo‐oophorectomy showed solitary intramyometrial metastatic lung adenocarcinoma with a second‐site T790M gatekeeper mutation in exon 20 of the EGFR gene. In conclusion, uterine metastasis from lung adenocarcinoma can present a diagnostic challenge. The possibility of lung cancer metastasis should be considered when a uterine mass increases in size during treatment. Molecular analysis of the EGFR gene to detect mutations could provide useful information for planning the treatment strategy.
Stakeholder Perspectives on Optimizing Communication in a School‐Centered Asthma Program
Authors: Snieder Hylke M. , Nickels Sarah , Gleason Melanie , McFarlane Arthur , Szefler Stanley J. , Allison Mandy A.
Published: November 2017

BACKGROUND

School‐centered asthma programs (SAPs) can be an effective intervention to improve asthma control for underserved populations but little is known about how key stakeholders communicate within these programs. Therefore, our aim was to identify key components of effective communication in a SAP.

METHODS

Primary care providers (PCPs), parents and school nurses associated with a SAP in Denver, Colorado participated in interviews and focus groups about their views on effective communication. Interview and focus group guides were developed using an appreciative inquiry approach and transcripts were analyzed via an iterative coding approach.

RESULTS

We conducted 3 focus groups with school nurses (N = 13), interviews with parents (N = 12) and PCPs (N = 10). Stakeholders identified multiple themes that enable communication, namely personal relationships, clear roles, integration of technology, adequate resources, and accessibility.

CONCLUSIONS

Communication in SAPs is most effective when there are clearly delineated roles with the school being the focal point for education and monitoring of asthmatic students and PCPs being the focal point for diagnosis and changes in care. Communication should take place using modern technology that is integrated into existing workflow. Information sharing is most likely to be successful if there is deliberate relationship building.
Addressing the Antinomy Between Health Education and Health Literacy in Advancing Personal Health and Public Health Outcomes
Authors: Belcastro Philip A. , Ramsaroop‐Hansen Hardaye
Published: November 2017

BACKGROUND

Health literacy evolved from a standard of English language proficiency designed to promote patient compliance into an inferential for promoting positive health decision‐making and health outcomes. In turn, the United States relegated health literacy as a national strategy to improve personal health and health care outcomes as well as reduce national health care expenditures.

METHODS

We reviewed the literature to assess the empirical research about health literacy and health behavior and health status outcomes.

RESULTS

There is a paucity of empirical research supporting health literacy's capacity to improve personal health behavior or health outcomes. We submit that the process of acquiring scientifically valid health knowledge partnered with the skills for informed health decision‐making as well as motivation to foster positive health behaviors and health outcomes is that of health education, and not that inferred by health literacy competency.

CONCLUSIONS

We recommend that comprehensive school health education serve as the standard for advancing personal health and health outcomes. We recommend that elementary, secondary, and higher education institutions be charged with the objective to provide comprehensive school health education intervention to advance personal health, community health, and concomitantly moderate national health care expenditures.
Health as a Predictor of Students' Academic Achievement: A 3‐Level Longitudinal Study of Finnish Adolescents
Authors: Minkkinen Jaana , Lindfors Pirjo , Kinnunen Jaana , Finell Eerika , Vainikainen Mari‐Pauliina , Karvonen Sakari , Rimpelä Arja
Published: November 2017

BACKGROUND

Studies have shown a relationship between students' health and their academic achievements, but whether health of classmates and schoolmates impacts individual students' school achievement is less known. We studied these effects on students in lower secondary school in Finland.

METHODS

Students (seventh grade, age 12‐13 years, N = 7779, 123 schools, 565 classes) participated in a classroom survey measuring health (externalizing and internalizing problems, daily health complaints, and long‐term illness) and academic achievement. Academic achievement when leaving school (15‐16 years) was obtained from the Finnish national application register on upper secondary education. Three‐level (student, class, and school) multilevel regression analyses were executed.

RESULTS

All health variables predicted academic achievement at leaving school at the student level and externalizing and internalizing problems at the class level; better health predicted better achievement. Students' health at the school level was not related to academic achievement. The effect of class‐level health on academic achievement was as strong as the effect of student‐level health.

CONCLUSION

Both student and classmates' health at the beginning of lower secondary school contribute to academic achievement when leaving school.
Primary stabilisation for tail avulsion in 15 cats
Authors: Caraty J. , Hassoun R. , Meheust P.
Published: November 2017

Objectives

To evaluate the effects of a primary tail stabilisation technique in relieving pain and supporting nerve recovery in cats that have lost voluntary motor function and pain sensation in the tail without caudal nerve transection.

Materials and Methods

Retrospective review of medical records and preoperative diagnostic tests, including clinical examination results and tail radiographs of cats suffering from tail avulsion with loss of pain perception in the tail between 2009 and 2015. Cats with open tail fracture, tail wounds that necessitated an amputation or caudal nerve root transection were excluded. Tail reconstruction was performed, after surgical exploration, with two nylon sutures.

Results

Fifteen cats were included, all of which had lost voluntary motor function in the tail and 8 of 15 were urinary incontinent. After surgery, 11 cats recovered voluntary tail function and pain sensation within 14 to 90 days (mean 39 days). Five of the eight previously incontinent cats recovered urinary continence within a month of surgery.

Clinical Significance

The reported method of primary tail stabilisation is associated with recovery of lost function in the majority of cats presenting with tail avulsions, loss of pain sensation in the tail but without caudal nerve root transection. A comparison study is required to determine whether these results are superior to conservative management.
Open models for patents: Giving patents a new lease on life?
Authors: Estèves Natacha
Published: November 2017

This essay investigates the development of peculiar models in patents: “Open patent” licenses, patent pledges, defensive patent strategies and the like. Although using patents in an unconventional way, these models do not dispute the very existence of patents, but rather the way patents are being used. These models are not entirely new—some have been around for over a decade—but seem to find an echo with the growing criticisms of the “broken patent system”. These models might be able to go beyond the pro‐patent/against patent debate, by reconciling exclusive/inclusive mechanisms and eventually reveal the strong plasticity of patents, offering patents a new lease on life.
Prepregnancy liver enzyme levels and risk of preeclampsia in a subsequent pregnancy: A population‐based cohort study
Authors: Cho Geum Joon , Kim Ho Yeon , Park Jong Heon , Ahn Ki‐Hoon , Hong Soon‐Cheol , Oh Min‐Jeong , Kim Hai‐Joong
Published: November 2017

Background & Aims

Preeclampsia is a serious multisystemic disorder leading to maternal and neonatal adverse outcomes. However, little is known about the early markers of this disease. The aim of this study was to investigate the association between prepregnancy liver function and the development of preeclampsia.

Methods

We enrolled 192 571 Korean women who had their first delivery between January 1, 2008, and December 31, 2014, and had undergone a national health screening examination through the National Health Insurance Corporation during 1‐2 years before delivery.

Results

Preeclampsia developed in 3973 (2.0%) women. The rate of development of preeclampsia was higher in women with abnormal prepregnancy liver enzyme levels than in those with normal liver enzyme levels before pregnancy. On multivariate analysis, women with abnormal alanine aminotransferase level before pregnancy had a 1.21‐fold increased risk of developing preeclampsia than those with normal alanine aminotransferase level before pregnancy, after adjusting for age, family history of hypertension, hepatitis B virus carrier status, smoking, alcohol status, prepregnancy body mass index and blood pressure. Prepregnancy γ‐glutamyltransferase and aspartate aminotransferase levels were not associated with the risk of preeclampsia development.

Conclusion

Abnormal prepregnancy alanine aminotransferase level was associated with the development of preeclampsia in a subsequent pregnancy. Further studies are needed to evaluate whether early intervention for liver function before pregnancy can decrease the risk of preeclampsia.
Dietary therapies for functional bowel symptoms: Recent advances, challenges, and future directions
Authors: Tuck C. J. , Vanner S. J.
Published: November 2017

Background

Functional gastrointestinal symptoms in irritable bowel syndrome (IBS) and quiescent inflammatory bowel disease (IBD) cause significant morbidity and a reduction in quality of life. Multiple dietary therapies are now available to treat these symptoms, but supporting evidence for many is limited. In addition to a further need for studies demonstrating efficacy and mechanism of action of dietary therapies, the risk of nutritional inadequacy, alterations to the microbiome and changes in quality of life are key concerns requiring elucidation. Identifying predictors of response to dietary therapy is an important goal as management could be tailored to the individual to target specific dietary components, and thereby reduce the level of dietary restriction necessary.

Purpose

This review discusses the available dietary therapies to treat symptoms in patients with IBS and patients with quiescent IBD suffering from IBS symptoms, with the aim to understand where current dietary evidence lies and how to move forward in dietary research in this field.
Unusual case of Pilomatrixomas with myotonic dystrophy
Authors: Ajao Hakeem , Carter Lachlan , Chengot Preetha
Published: November 2017

A 40‐year‐old female Caucasian patient presented at the Oral and Maxillo‐facial clinic Leeds Dental Institute with a 12‐month history of multiple firm nodules in the left scalp, right temple and right posterior neck, eight in number. The patient also suffers from myotonic dystrophy and hypothyroidism. Excisional biopsy reveal circumscribed nodules composed of varying proportions of basaloid cells, eosinophilic ghost cells in the central part, calcifications and foreign body‐type giant cells. The appearances are entirely in keeping with Pilomatrixoma.
Upstream kinases of plant SnRKs are involved in salt stress tolerance
Authors: Barajas‐Lopez Juan de Dios , Moreno Jose Ramon , Gamez‐Arjona Francisco M. , Pardo Jose M. , Punkkinen Matleena , Zhu Jian‐Kang , Quintero Francisco J. , Fujii Hiroaki
Published: November 2017

Sucrose non‐fermenting 1‐related protein kinases (SnRKs) are important for plant growth and stress responses. This family has three clades: SnRK1, SnRK2 and SnRK3. Although plant SnRKs are thought to be activated by upstream kinases, the overall mechanism remains obscure. Geminivirus Rep‐Interacting Kinase (GRIK)1 and GRIK2 phosphorylate SnRK1s, which are involved in sugar/energy sensing, and the grik1‐1 grik2‐1 double mutant shows growth retardation under regular growth conditions. In this study, we established another Arabidopsis mutant line harbouring a different allele of gene GRIK1 (grik1‐2 grik2‐1) that grows similarly to the wild‐type, enabling us to evaluate the function of GRIKs under stress conditions. In the grik1‐2 grik2‐1 double mutant, phosphorylation of SnRK1.1 was reduced, but not eliminated, suggesting that the grik1‐2 mutation is a weak allele. In addition to high sensitivity to glucose, the grik1‐2 grik2‐1 mutant was sensitive to high salt, indicating that GRIKs are also involved in salinity signalling pathways. Salt Overly Sensitive (SOS)2, a member of the SnRK3 subfamily, is a critical mediator of the response to salinity. GRIK1 phosphorylated SOS2 in vitro, resulting in elevated kinase activity of SOS2. The salt tolerance of sos2 was restored to normal levels by wild‐type SOS2, but not by a mutated form of SOS2 lacking the T168 residue phosphorylated by GRIK1. Activation of SOS2 by GRIK1 was also demonstrated in a reconstituted system in yeast. Our results indicate that GRIKs phosphorylate and activate SnRK1 and other members of the SnRK3 family, and that they play important roles in multiple signalling pathways in vivo.
Accuracy of 3 Tesla magnetic resonance imaging using detection of fiber loss and a visual analog scale for diagnosing partial and complete cranial cruciate ligament ruptures in dogs
Authors: Fazio Constance G. , Muir Peter , Schaefer Susan L. , Waller Kenneth R.
Published: November 2017

Canine cranial cruciate ligament rupture is often bilateral and asymmetrical, ranging from partial to complete rupture. The purpose of our diagnostic accuracy study was to assess the accuracy of 3 Tesla magnetic resonance imaging (MRI) detection of fiber loss and use of a visual analog scale in the diagnosis of complete versus partial cranial cruciate ligament rupture in 28 clinical dogs with unilateral complete rupture and contralateral partial rupture. Three Tesla MRI was performed on 56 stifles using sagittal sequences (T2‐weighted fast spin echo with fat saturation, proton density fast spin echo, and T2‐weighted 3D fast spin echo CUBE). Two MRI observers assessed the cranial cruciate ligament for fiber loss and completed a visual analog scale. The MRI data were compared to arthroscopy and clinical status. Accuracy classifying partial or complete rupture was assessed using receiver operating characteristic analysis. Compared to arthroscopy, for complete cranial cruciate ligament rupture, sensitivity, specificity, and accuracy of MRI detection of fiber loss were 0.78, 0.50–0.60, and 0.68–0.71, respectively, and, for partial tears, specificity was 1.00. An MRI visual analog scale score ≥79 was indicative of complete cranial cruciate ligament rupture (sensitivity 0.72–0.94 and specificity 0.71–0.84). Using a visual analog scale cut‐point ≥79, observers achieved good accuracy discriminating clinical status of partial or complete cranial cruciate ligament rupture (area under the curve 0.87–0.93). MRI evaluation for fiber loss and use of a visual analog scale are specific in stifles with clinically stable partial cranial cruciate ligament rupture. In stifles with clinically unstable complete cranial cruciate ligament rupture, both MRI tests are sensitive though not specific compared to arthroscopy. As a diagnostic imaging method, MRI may help guide treatment in patients with cranial cruciate ligament damage, particularly for stable partial rupture.
Integrated process planning, WSPT scheduling and WSLK due-date assignment using genetic algorithms and evolutionary strategies
Authors: Demir Halil Ibrahim , Canpolat Onur
Published: November 2017

Process planning, scheduling and due-date assignment are three important manufacturing functions in our life. They all try to get local optima and there can be enormous loss in overall performance value if they are handled separately. That is why they should be handled concurrently. Although integrated process planning and scheduling with due date assignment problem is not addressed much in the literature, there are numerous works on integrated process planning and scheduling and many works on scheduling with due date assignment. Most of the works in the literature assign common due date for the jobs waiting and due dates are determined without taking into account of the weights of the customers. Here process planning function is integrated with weighted shortest processing times (WSPT) scheduling and weighted slack (WSLK) due date assignment. In this study unique due dates are given to each customer and important customers gets closer due dates. Integration of these three functions is tested for different levels of integration with genetic algorithms, evolutionary strategies, hybrid genetic algorithms, hybrid evolutionary strategies and random search techniques. Best combinations are found as full integration with genetic search and hybrid genetic search. Integration of these three functions provided substantial improvements in global performance.
Non-monotonicity of Fano factor in a stochastic model for protein expression with sequesterisation at decoy binding sites
Authors: Hojcka Michal , Bokes Pavol
Published: November 2017

We present a stochastic model motivatedВ by gene expression which incorporates unspecific interactionsВ between proteins and binding sites. WeВ focus on characterizing the distribution of free (i.e.В unbound) protein molecules in a cell. Although itВ cannot be expressed in a closed form, we presentВ three different approaches to obtain it: stochastic simulationВ algorithms, system of ODEs and quasi-steadystateВ solution. Additionally we use a large-system-sizeВ scaling to derive statistical measures of approximateВ distribution of the amount of free protein, such as theВ Fano factor. Intriguingly, we report that while in the absence of or in the excess of decoy binding sites theВ Fano factor is equal to one (suggestive of PoissonianВ fluctuations), in the intermediate regimes of moderateВ levels of binding sites the Fano factor is greater thanВ one (suggestive of super-Poissonian fluctuations). WeВ support and illustrate all of our results with numericalВ simulations.
Design and Experimental Validation of an Active Catheter for Endovascular Navigation
Authors: Couture Thibault , Szewczyk Jérôme
Published: November 2017

Endovascular techniques have many advantages but rely strongly on operator skills and experience. Robotically steerable catheters have been developed but few are clinically available. We describe here the development of an active and efficient catheter based on shape memory alloys (SMA) actuators. We first established the specifications of our device considering anatomical constraints. We then present a new method for building active SMA-based catheters. The proposed method relies on the use of a core body made of three parallel metallic beams and integrates wire-shaped SMA actuators. The complete device is encapsulated into a standard 6F catheter for safety purposes. A trial-and-error campaign comparing 70 different prototypes was conducted to determine the best dimensions of the core structure and of the SMA actuators with respect to the imposed specifications. The final prototype was tested on a silicon-based arterial model and on a 23 kg pig. During these experiments, we were able to cannulate the supra-aortic trunks and the renal arteries with different angulations and without any complication. A second major contribution of this paper is the derivation of a reliable mathematical model for predicting the bending angle of our active catheters. We first use this model to state some general qualitative rules useful for an iterative dimensional optimization. We then perform a quantitative comparison between the actual and the predicted bending angles for a set of 13 different prototypes. The relative error is less than 20% for bending angles between 100 deg and 150 deg, which is the interval of interest for our applications.
Research on a Generating Method of Spiral Flutes of Hourglass Worm Gear Hob
Authors: Jie Yang , Haitao Li , Chengjie Rui , Wenjun Wei , Xuezhu Dong
Published: November 2017

All of the cutting edges on an hourglass worm gear hob have different shapes and spiral angles. If the spiral angles are small, straight flutes are usually adopted. But for the hob with multiple threads, the absolute values of the negative rake angles at one side of the cutting teeth will greatly affect the cutting performance of the hob if straight flutes are still used. Therefore, spiral flutes are usually adopted to solve the problem. However, no method of determination of the spiral flute of the hourglass worm gear hob has been put forward till now. Based on the curved surface generating theory and the hourglass worm forming principle, a generating method for the spiral flute of the planar double enveloping worm gear hob is put forward in this paper. A mathematical model is built to generate the spiral flute. The rake angles of all cutting teeth of the hob are calculated. The laws of the rake angles of the cutting teeth of four hobs with different threads from one to four threads are analyzed when straight flutes and spiral flutes are adopted respectively. The laws between the value of the negative rake angles of the hob with four threads and the milling transmission ratio are studied. The most appropriate milling transmission ratio for generating the spiral flute is obtained. The machining of the spiral flutes is simulated by a virtual manufacturing system and the results verify the correctness of the method.
A Novel Time-Varying Spectrum Based Approach to Active Disturbance Rejection Control
Authors: Pu Zhiqiang , Tan Xiangmin , Yuan Ruyi , Yi Jianqiang
Published: November 2017

This paper presents a comprehensive framework for developing a novel time-varying spectrum based active disturbance rejection control (TVS-ADRC) technique. It complements conventional linear or nonlinear ADRC by introducing time-varying components, including time-varying extended state observer, time-varying tracking differentiator, and time-varying feedback, to offer better design flexibility and improved performance in command filtering, disturbance observation, and closed-loop control. First, skeleton stability and convergence analysis is introduced based on differential algebraic spectral theory. Then parameter tuning is categorized into two time-varying principles: a time-based profile and a state-dependent function, and a unified parameterization approach is given by assigning time-varying eigenvalues. Typical applications are pointed out which demonstrate great advantages of TVS-ADRC in consideration of varying plant or environment features and physical limits in practical systems. Challenges and future work for the TVS-ADRC technique are also summarized in the end.
Design of Multi-Purpose Products: Guidelines From a User Perspective
Authors: Viswanathan Vimal , Sangelkar Shraddha
Published: November 2017

Multipurpose products are the artifacts with more than one intended or realized purposes. Abundance of multipurpose products in the market raises interesting questions about the desired customer preferences that lead to success or failure of such products in the market. This study aims to set the premise for developing design guidelines for multipurpose products. The study described in this paper is a qualitative content analysis of reviews of multi-purpose products available from online vendors. A traditional content analysis method is followed, where each sentence from the reviews is coded and categorized by three reviewers. Each category is then carefully analyzed and any redundancies are resolved. Finally, an interrater agreement is achieved between the three coders. The obtained categories shed light on customer expectations from multi-purpose products, their concerns, comments and experiences and their advice from the customer’s viewpoint for the design of such products. Each category identified here shows a potential research direction and a foundation for developing new guidelines for the development of such products.
An Improved Re-Scaling Frequency Stochastic Resonance and its Application to Weak Fault Signal Detection
Authors: Liu Jin-Jun , Leng Yong-Gang , Fan Sheng-Bo , Ma Xiao-Jun
Published: November 2017

Weak fault detection is crucial to incipient mechanical fault diagnosis. In order to extract weak fault signals, a method named improved Re-scaling Frequency Stochastic Resonance (IRFSR) is proposed in this paper. The method consists of four steps: (i) Frequency Information Exchange (FIE); (ii) Amplitude Coefficient Adjustment; (iii) Re-scaling Frequency Stochastic Resonance (RFSR); and (iv) Frequency Information Recovery. By means of the exchange of frequency information, the high-frequency information of the target signal is accordingly transferred to the low frequency band which can be rescaled to satisfy the small-parameter limits of classical stochastic resonance. Then IRFSR is able to overcome the limitation of RFSR, which is that the sampling frequency of RFSR is at least 50 times greater than the frequency of the target signal. Numerical results are reported to evaluate the effectiveness of IRFSR to detect the target signal with higher frequency at a low sampling frequency as compared with RFSR. And the feasibility of the IRFSR in incipient fault detection is demonstrated using case history data obtained from a sliding bearing test rig.
Reliability-Based Topology Optimization Using Mean-Value Second-Order Saddlepoint Approximation
Authors: Papadimitriou Dimitrios , Mourelatos Zissimos P.
Published: November 2017

A reliability-based topology optimization (RBTO) approach is presented using a new mean-value second-order saddlepoint approximation (MVSOSA) method to calculate the probability of failure. The topology optimizer is based on a discrete adjoint formulation. MVSOSA is based on a second-order Taylor expansion of the limit state function at the mean values of the random variables. The first and second-order sensitivity derivatives of the limit state cumulant generating function with respect to the random variables in MVSOSA, are computed using direct-differentiation of the structural equations. Third-order sensitivity derivatives, including the sensitivities of the saddlepoint, are computed using the adjoint approach. The accuracy of the proposed MVSOSA reliability method is demonstrated using a nonlinear mathematical example. The results are compared with the available mean value first-order saddlepoint approximation (MVFOSA) method and Monte Carlo simulation. Finally, the proposed RBTO-MVSOSA method for minimizing compliance-based probability of failure, is demonstrated using two 2D beam structures under random loading.
Dynamics and Power Absorption of a Self-React Wave Energy Converter With Mechanical Power Takeoff System
Authors: Liang Changwei , Li Xiaofan , Martin Dillon , Wise Adam , Parker Robert , Ngo Khai , Zuo Lei
Published: November 2017

A self-react wave energy converter which consists of a floating buoy and a submerged body is studied in this paper. The energy is extracted through the relative motion of the floating buoy and submerged body. Two kinds of power takeoff (PTO) system, which is the technique approaches to extract energy from the ocean, are considered for the proposed wave energy converter. One is a ball screw system with mechanical motion rectifier gearbox (which is called MMR system) and another one is solely a ball screw system (which is called non-MMR system as a comparison). The design of the proposed wave energy converter is presented and the model for both power takeoff systems are established based on their mechanisms. A time domain method is adopted to investigate the dynamics and power absorption for the proposed wave energy converter. The effect of equivalent mass on the optimal power and corresponding optimal power takeoff damping are studied both in regular and irregular waves. It is found that the equivalent mass plays different roles in the MMR system and non-MMR system. Due to the disengagement in MMR system, the equivalent mass helps to increase the power absorption at small wave 1periods, both in regular waves and irregular waves. The uncertainty of the drag coefficient on the power absorption of MMR system and non-MMR system is also investigated.
Dynamic Stiffness Model of Planetary Roller Screw Mechanism With Clearance, Geometry Errors and Rolling-Sliding Friction
Authors: Ma Shangjun , Peng Cheng , Li Xiaofeng , Liu Geng
Published: November 2017

This paper applies the bond graph theory to construct a dynamic stiffness calculation model for the planetary roller screw mechanism with factors such as structural stiffness and contact stiffness of screw, clearances, geometry errors, rolling-sliding friction, and load distributions on the roller threads and a group of rollers under two installation modes. In addition to predicting how dynamic stiffness varies with the load frequency and load amplitude under two installation modes, how does it change with the structural parameters such as screw diameter, helix angle, contact angle and number of roller threads under two installation modes are also investigated. The results can provide theoretical basis for the design of planetary roller screw mechanism considering dynamic stiffness with the influences of clearances, geometry errors, friction and installation modes.
Implementation of Frequency-Based Classification of Damages in Composites Using Real-Time FPGA-Based Hardware Framework
Authors: Cunha Adauto P. A. , Wirtz Sebastian F. , Söffker Dirk , Beganovic Nejra
Published: November 2017

Structural Health Monitoring (SHM) systems become an integral part of most technical systems in recent years. An integration of SHM in technical systems is closely related to: i) providing the guaranteed service lifetime of a system, ii) scheduled/planned maintenance actions, and iii) optimized system operation. For these purposes, different system variables can be monitored and utilized for an estimation of aging level of the system. Monitored system variables are therefore correlated to stochastically occurring damage, indirectly also to Remaining Useful Lifetime (RUL). Among challenges related to SHM, high attention is given to the reduction of a large amount of measured data and its real-time signal processing. In this contribution, classification of damages in composite materials using measurements of Acoustic Emission (AE) is proposed. Here, Discrete Wavelet Transform (DWT) is applied to AE signal to identify different damages in composites. As AE-signal is found in high frequency bandwidth, the amount of data captured in a short time period is enormous. Consequently, the calculation of DWT of such signal requires processing time quite far from real time and delays the entire classification procedure. Due to this, real-time implementation of DWT is proposed to cope with huge amount of captured data in this case and to reduce the time required for signal processing. Using FPGA-based system, real-time implementation of DWT is shown. Obtained results are compared with the results of offline DWT calculation to prove the efficiency and accuracy of real-time implementation.
Correction of Multiple Transducers Masses Effects From the Measured FRFS
Authors: Ren Jun , Wang Jun , Zhou Xiaodong , Ting Kwun-Lon
Published: November 2017

In modal testing, the measured Frequency Response Functions (FRFs) are often affected by transducer mass effects. Especially in Multi-Input-Multi-Output (MIMO) modal test, multiple sensors are employed and the effects of additional masses are more significant. This paper deal with removing masses effects of multiple sensors from the measured FRFs. The proposed method offers some advantages over the available techniques in that extra FRFs measurements with different configurations are not required during the correction process. First, a general correction formulation is derived theoretically. Then, validations of the proposed methods are demonstrated using simulated data. It demonstrates a good performance in numerical simulation. To investigate the performance of the proposed method in practical application, further simulations are presented by employing noise-polluted data. And it is shown that the accuracy of correction results will be affected to some extent by the noise. It is thus suggested that the measured FRFs be preprocessed using the curve-fitting procedure or noise reduction processing before applying the proposed method. Since the FRFs measurements required for corrections refer to different excitation points, it requires moving the exciter to different locations. This is usually easy to achieve in hammer impact testing. However, moving the exciter is usually inconvenient in shaker modal testing. Further work is necessary to extend this proposed method so as to make it also applicable for shaker modal test case.
An Experimental Study of Influence of Lubrication Methods on Efficiency and Contact Fatigue Life of Spur Gears
Authors: Moss J. , Kahraman A. , Wink C.
Published: November 2017

An experimental investigation of spur gear behavior was conducted with the aim of quantifying the impact of lubrication methods and conditions on the power losses and contact fatigue lives. Variations of dip and jet-lubrication were defined and these behaviors were observed as a function of the lubrication conditions. All measurements were performed using the same back-to-back test machine and the same spur gear test articles such that all evaluations were correlated. Power loss experiments were performed under both loaded and unloaded conditions to determine both load-independent (spin) and load-dependent (mechanical) losses. Sets of long-cycle contact fatigue experiments were performed under the same lubrication conditions to determine macro-pitting lives in a statistically meaningful manner. Results indicate that the spin power losses are impacted by the lubrication method significantly while the mechanical losses are not influenced. Contact fatigue lives from jet-lubricated tests are comparable to those under dip-lubricated conditions ones as long as jet velocities are sufficient.
Multi-Resonant Electromagnetic Shunt Dampers for Vibration Suppression
Authors: Pei Yalu , Zuo Lei
Published: November 2017

This paper proposed multi-resonant electromagnetic (EM) shunt dampers and investigated the optimal designs and performances of shunt circuits for a single DOF primary system. The circuits are arranged in parallel or series based on the analogy of multiple tuned mass dampers (TMDs). The objective is to minimize the root-mean-square (RMS) vibration of the primary system subjected to random base excitations. For single resonant EM shunt damper, closed-form solutions of optimal system parameters are obtained. For multi-resonant EM shunt dampers, the system parameters are numerically optimized. The vibration suppression performance of multi-resonant EM shunt dampers are compared with double-mass TMDs under the same 5% total stiffness ratio. It shows that the parallel shunt damper can achieve slightly better performance than parallel TMDs while the series shunt damper behaves differently from series TMDs. The optimal result of the series shunt damper will be the same as the single resonant shunt damper. It is also found that the multi-resonant EM shunt damper is much more sensitive to the capacitance than the resistance in the shunt circuits.
An Assessment of Village Drill Sustainability, With Recommendations
Authors: Pack Andrew T. , Mattson Christopher A.
Published: November 2017

Sustainability is commonly broken into three categories: economic, environmental, and social. For products, there is a need for design tools that allow decision makers to handle the tradeoffs between each of these three pillars of sustainability. This paper simultaneously assesses all three pillars of sustainability for the Village Drill, a machine used to dig water wells in rural areas around the world. Using data and methods from Mattson et al. [1, 2] relationships are developed between the drill’s design parameters and key sustainability issues. These relationships are used to evaluate the sustainability of the current drill design as well as any alternatives. One million random sets of drill parameters are generated and the resulting drill alternatives are evaluated. A three-dimensional design space for the sustainability of the drill is found and recommendations are given with potential for improvements in each pillar of sustainability.
Use of Numerical-Clustering Framework for End-Effector Tracking During Robot-Assisted Surgery
Authors: Shafiei Somayeh B. , Guru Khurshid A.
Published: November 2017

Imaging plays an important role in all clinical processes. One challenge in medical image data processing is detection and tracking objects and instruments, which faces complications arising from the developed medical image acquisition systems and also the nature of in-vivo medical images. Special properties of the in-vivo bio images such as noise, specular highlights, inhomogeneity, heterogeneity, varying luminosity, and background change, in addition to the changes of camera, out of camera view tools, and multiple moving tools (instrument tools, surgical suture, cutting instrument, tissue movement) make object detection and tracking in the biomedical image processing complicated. In this study, the k-means clustering method in combination with the level set active curve model are used to develop a platform for low-cost tracking of surgical tools in robotic surgery videos. After removing the image background, the smoothed image is used as input to the numerical method. This model tracks the robot tools even when the camera view changes, the tool is lost, the tissue is bleeding and moving, and the luminosity of the images changes. The developed model is validated using video frames of real and simulated robotic surgeries. The accuracy of model in tracking da vinci robot end-effectors for a video with 12000 frames, recorded at Roswell Park Cancer Institute, is 93%. Accuracy of proposed framework is compared to those for existing numerical models, DRLSE and Chan-Vese. The results show that proposed surgical robot tool tracking model is more efficient than existing computational models.
Force Diverting Helmet Liner Achieved Through a Lattice of Multi-Material Compliant Mechanisms
Authors: Gokhale Vaibhav , Tapkir Prasad , Tovar Andres
Published: November 2017

This work introduces the design of a lattice array of multi-material compliant mechanisms (LCM) that diverts the impact radial force into tangential forces through the action of elastic hinges and connecting springs. When used as the helmet liner, the LCM liner design has the potential to reduce the risk of head injury through improved impact energy attenuation. The compliant mechanism array in the liner is optimized using a multi-material topology optimization algorithm. The performance of the LCM liner design is compared with the one obtained by expanded polypropylene (EPP) foam, which is traditionally used in sport helmets. An impact test is carried out using explicit, dynamic, nonlinear finite element analysis. The parameters under consideration include the internal energy, the peak linear force, as well as von Mises stress and effective plastic strain distributions. Although there is a small increase in stress and strain values, the simulations show that the maximum internal of the LCM liner design is four times the one of the foam design while the peak linear force is reduced to about half. While the use of the LCM liner design is intended for sports helmets, this design may find application in other energy absorbing structures such as crashworthy vehicle components, blast mitigating structures, and protective gear.
Ontologies to Support Customer Requirement Formulation in Aerospace Design
Authors: Lemke Mark T. , Stone Robert B. , Arlitt Ryan A.
Published: November 2017

The major goal of customer requirement formulation is to achieve a common understanding between the project stakeholders and the engineering requirements. Many times, this process can be ambiguous, incomplete, and time consuming especially when more than one engineering discipline is involved. Therefore, adequate requirement formulation tools can be a major contributor to solving these challenges. The use of ontologies provides a standardized way of describing concepts in a domain of interest and the relationships between these concepts to better understand the domain as a whole. This paper describes the methodology used to create an ontology derived from twenty customer requirements of a mid-size, twin-engine, commercial transport-class aircraft provided by NASA Ames Research Center. One key stipulation that NASA had was that this ontology effectively captures the relationships that exist between the hardware and software level of each customer requirement. The final ontology was created using Protégé OWL, an open source ontology editor, which will be used by NASA in order to improve the customer requirement creation phase of future NASA products. The ontology and requirements were further generalized into a set of common patterns for describing requirements in this domain. These pattern templates provide a tool to ensure that common styles of requirements have been considered, and that these common styles are uniform. This research paper fills a gap in the customer requirement research field by introducing the use of ontologies and common patterns to reduce ambiguity and repetition.
A Flow-Induced Structure-Based Kinetic Energy Harvester
Authors: Zhang Guangcheng , Lin Yueh-Jaw , Klumpner Christian
Published: November 2017

In this paper, a strategy utilizing a pair of cylinders which are put on both sides of the cantilever beam and perpendicular to the water flow direction to harvest the energy is demonstrated. The novel flow-induced structure-based energy harvester consists of a pair of inducing objects (cylinders) and one L-type cantilever beam. Macro fiber composite (MFC) is attached at the fixed end of the cantilever beam to convert the kinetic energy into electric power. The structure could induce the vortex shedding from the upstream flow and harvest the energy from it. Compared with the former studies regarding one or series layout inducing objects, the proposed structure could both improve the power output of the flow-induced energy harvester and avoid the damage happening in complex working conditions. Analytical modelling and experiment methods are both utilized in the research to cross verify the results. The characteristics related with water flow speed and center distance variations between inducing objects are discussed in the paper as well. It is found that when the water flow speed is 0.2m/s and the center distance is 30mm, the output power is optimal of 0.16μW and the power density is 0.4mW/m2.